Cambridge CD2 manuals, schematics & mods

Does anyone have any information on the Cambridge CD2 manuals, schematics and modifications.

I intend to fit the Elso Kwak clock.
Also a common problem with the cd2 is with the display switching left to right.

I built this circuit back in the year 2002 and I used it as a driving stage for my class A power buffer PM-A1 (gain 1x, 30W/8ohm). It was working very well with quite good parameters, as can be seen below.



(D1 is a Zener diode 6V8)



I am showing above the THD+N plot (1kHz, BW40kHz) to include noise part as well. This is often omitted, unfortunately.

Loopgain stability is perfect, with 87° phase margin.

I salvaged a pair of mini piezos and was thinking of adding them as super-tweeters.
Do they need a cap? They were originally installed behind 2.2uF?
Do they need a resistor? What does the resistor do?

I came across these seemingly obscure drivers but could find very little about them. They look to be well engineered but outer beauty can be deceptive.

Anyone try these? How do they compare with other higher end cone drivers?

We discussed previously whether or not EnABL would improve a MAOP driver, and I volunteered my MAOP-7 to try it. Sorry, couldn't do it earlier. Preparations for winter occupied most of my time - I live in a countryside.

First, I tried to do tap test to determine optimal positions of the patterns. It didn't work - at any distance on the cone radius tap sound was the same. Tapping worked on a 4" Sony speaker with a paper cone, I could find positions where tap produced the loudest sound. I guess the MAOP cone is pretty well-damped as-is. Without tap test guidance, I decided to apply patterns 1) close to surround; 2) on former close to cone boundary, and 3) on top of the dome. See pictures for details.

The patterns were applied free-hand using extra fine Utilto acrylic paint markers, black and white. Surround pattern was applied to back side of the cone to conceal my ugly handiwork. To build up thickness (pens lay paint pretty thin), three layers were applied: black-white-black. On the cap, a single layer of white.

The difference showed on the first test record, Beatrice Rana Chopin Preludes. This is a very well recorded piano album. The second prelude is played between piano and pianissimo. Control untreated driver played soft, but with the EnABLed driver I could hear string buzz that wasn't apparent before. Those familiar with the sound of top level instruments like Steinway or Fazioli will understand what I am talking about.

Further testing is unnecessary. It worked.

Time for another set of bedroom speakers.
Of the SB tweeters available here in Oz which model comes closest to the old Vifa D27-45-06?
I just scored some NOS Vifa P-14s and I've got no suitable tweeter as easy to use in the stash.
Cost effectiveness is paramount so nothing from the Satori line

I'm building a subwoofer for the trunk of my Subaru Crosstrek.

I have 42.5in x 26in and would prefer the height be 2-4in. I'm having trouble with tuning of the box, as if the port is too wide the speakers go into over excursion, if they are thinner they easily go over 18m/s. I'm not sure how to model tapered waveguides or adding a flare in terms of port length. I'm a mech e but new to audio design, so joined here to learn as much as I could about complex analysis and subwoofer optimization.

I've tried sealed box, ported, 4th order (to basically act as a spring to reduce excursion, but I'm limited on tuning frequency because the back volume can't get any bigger without overexcursion), 6th order series and parallel, have played with 12in low profile sub, but don't know how to simulate downfiring and top must be encloseed as it will be the new trunk surface. The 12in is also pretty tall.

I'd be using an LX1300.1 with about 550W at a 2ohm load. Design shown is 6 Dayton Audio 2x7s. I'm trying to get low. I will have 2x 10in self powered el cheapos behind the driver and passenger seats, which will cover the 60-100hz range fine. That's what I did in the truck and it did the trick. I've never had low low bass and don't want to miss out on this opportunity with a brand new car.

I've attached a few pictures, but I've been through very many iterations, these are just some recent ones to show the process of building the subwoofer.

I'm also not opposed to passive radiators, but the only 2in or less ones are cheapo knockoffs with no TS parameters for excursion or moving mass or anything so I don't know how to begin that calculation.

We can't always afford polypropylene capacitors, much less
Teflon (tm), so we often make do with electrolytics when
we need those higher values.

There's all sorts of caps out there with claims to being better,
and they certainly are more expensive.

My favorite is the Elna silk capacitors, available from Digikey,
and really cheap. The measure spectacularly, sound great,
and the manufacturer's translated description of why they
sound better is a Babelfish classic.

So before you run out and spend a lot on the highly hyped
spendy caps, try the Elna silk caps.

There's hemp in them, too.

😎

The post in the newcomer reporting area has been closed

This device is purely a personal DIY, and all the components come from online shopping. There is only one device, and I am not some kind of equipment supplier.

Basic idea:
TPA3255(600w) x 6 + 50V1000W + 15V+/- Switching Power + LT3045/LT3094 + 7*JRC5532DD + miniPC + Terratec 7.1USB sound card + Roon Server

Hi There
I have this amp which just stopped working. No Power.
I opened it up and so far I’ve spotted 2 resistors that look like they’ve heated up. On the right.
No schematics ,so only have visuals at the moment.
Any help would be good.
I’ve got it’s bigger brother (IPS3700) aswell with the same fault but leaving that one for now.
Cheers 🍻

Single-Supply Preamps For Guitar

Here are six preamps for guitar using op-amps; each operated from a single 9V battery as the power supply, thus making them suitable for stomp-box applications. Sources for the diagrams are noted with the diagrams. The circuits are faithful to original diagrams but for minor changes, such as the adding of an input level control or the use of a pot in a negative feedback loop to provide the user with a gain control. However, while based on proven designs, these designs must still be considered experimental. Also, the diagrams originally posted had flaws, which were corrected according to advice from forum members here, who I thank for their help. The diagrams shown now are updated versions (but some may be updated again if needed).



The specified IC is the OPA2156 dual low-noise op-amp IC, but an original TI unit can be expensive and may take a long time for delivery. So, I have listed a number of pin-compatible substitutes at the end of this post, all of which will provide good results.

The next circuit features a Baxandall type of 2-band tone-control, followed by one with a Fender-style 2-band control, which works differently from the Baxandall-type, though both leave the mids fixed. For those who prefer three bands, all other circuits below involve 3-band Fender-style tone stacks.



Note the seemingly redundant Tone control at the output below. That is included to provide an additional means of shaping high-end response.



What follows next are the preamps with the 3-band tone-stacks having default Fender Bassman part-values.



Consider the difference in the way the input and output jacks are shown below. This would be a good way to do the foregoing circuits too, but I show this configuration only for the last two circuits. This one also has a fuzz circuit using diodes, providing clipping without having to overdrive op-amps. But if that is desired, an older dual JFET-input IC can be considered, having minimum supply voltage <= 4.5 V, such as the LF353.



The circuit below likewise has a diode-type fuzz circuit, but which is highly adjustable.




Here is the pinout diagram for a dual op-amp, along with pin-compatible example ICs.



ICs listed here should perform satisfactorily for the electric guitar and offer the least noise and distortion for circuits operated using a single 9V battery. They were chosen from among the best op-amps available today but whose minimum supply voltage is <= 4.5 VDC, since half of 9V is 4.5V, and a single-supply circuit sets the zero signal-reference operating-point midway between ground and the supply.

To get more distortion than the diodes provide, by overdriving a given circuit, use the LF353 instead of any of the ICs listed above. It is an older op-amp that will work with a single 9V battery as the supply and is a JFET-input op-amp, which means its overdriven tonality is preferred over that of most non-JFET-input op-amps. However, it will also work fine without being overdriven, and will not drain the battery nearly as fast as those listed above.

Note On Fuzz Circuits: The diode-based fuzz circuit used in the last two preamps are based on article “Build The Mod Box” by Thomas Henry and Jack Orman, in the May 1997 Electronics Now magazine (p.45). Obtain the article free online with this link.
https://www.muzique.com/news/images2/Mod_Box_May_1997.pdf
It originally specified the TL074 quad op-amp since it had four sub-circuits, and was operated from a split-supply. And despite being somewhat dated (25 years old), the circuitry has remained valid to this day, though I have adapted the diode arrays to conform to a single-supply circuit.

Additional Notes: Most circuits here are based on designs in the book “Building Electric Guitars” by Martin Koch. [$33.56 on eBay.] But the input stage of the second preamp is instead based on a design by Craig Anderton appearing in the Nov. 1981 issue of Guitar Player magazine. [Original issues start at $10.00 on eBay.] Those exact circuits cannot be found online, so a link to them is not available. Yet, I have depicted them accurately but for the minor additions I mentioned at the beginning of this post. Furthermore, while I receive much help diagnosing the diagrams I posted at first, I supplemented that help with online research, and an electronics textbook used at an accredited university. Consequently, all diagrams above have been updated and should be viable, but I would still treat them as experimental until after breadboard testing efforts have been completed.

Final Note: For comparison, the diagrams originally posted have been retained in the Attachments folder at the bottom of this post, while the updated versions are also there. I am embarrassed by the original ones, but proud of the new ones, though members who helped me with them deserve lots of credit. One thing should be mentioned, however, regarding the 0.2uF capacitors going to ground on the second stages of most of the diagrams. That, along with its associated resistor, sets the low-frequency cutoff for the associated op-amp at 80 Hz for 6-string guitar. But for bass-guitar, and 7-string or 8-string guitar, make it 0.43uF, for a 40 Hz cutoff. And for no low cutoff at all, it can be omitted. And by the way, the following replies correspond to the original diagrams, not the new ones. So, if you want to know what they are talking about, refer to the old diagrams as left in the Attachments.

EOF

Thanks for having me.
Recently heard some Tube amps and they blew my class D amps out of the water.

Nice to meet you!

I finally registered here as I find here lots of good information from which I learned a lot and want to learn more and help too if I know about someone's doubt.

Need to replace the left front speaker terminal. The plastic broke and now I only have the rear channel.

Hi all. I run this little Magnavox amp on my desk. Just recently, I started hearing different frequency sounds coming out of my speakers. The frequency is higher pitched at lower volumes and goes lower as I turn up the volume. Any ideas what going on?

I started this thread for IRFP240 Quasi: https://www.diyaudio.com/community/threads/quasi-irfp240-amplifier.428495/
Now I use another MOSFET transistor for better qualities.
I use Exicon Lateral ECX10N20 for this thread.

The benefits are three:
1. Somewhat less distortion, THD 0.005%
2. Higher max output, 25 Watt in 8 Ohm
3. No need for MOSFET protection diodes, are already built in

Here is the schematic. Enjoy 🙂

If I clog up the high side of my sixth order parallel band pass i I still get those quarter wave resonances ?

Are they based on the 120 cm resonator (it’s a big vented reflex) ?

(Video by @maxolini )

Some amplifiers, like the P3A by Rod Elliott for example, use a PNP transistor for the VAS, others use NPN, like the blameless amp by mr Self.
Does it matter? looking forward to your well founded opinions.

Hi everyone!

It's been almost two years since I last built a speaker, and I'm getting the urge again.

[TLDR:
A more compact floorstander using an SB Acoustics SB15SFCR39 for bass in a vented enclosure, extending further down to the early 20hz with boundary/room loading. The B&C 5CXN44 in a sealed enclosure for mid and high.]

My current setup is really good (here), but a few aspects have me considering a change:

Size: The speakers are quite large.
Low-end Limitation: They only reach down to 35hz with boundary loading.
Horizontal Coverage: It's not as wide as I'd like.
Practicality: The horn on top is a bit of a concern, especially with baby GG² about to start walking.



As you can see below the measured 'anechoic' response yields quite a bit more low-end extension when in the listening position. I thought this would be fine but there has been the odd movie or song that lacks a little in the rumble department. Boundary loading really is my friend here (more on that later).




Shortly after building these I added Dirac and that improved things a lot over my manual room correction (manual not shown).



When I made my workshop speakers (here) I really enjoyed the sound of the B&C 5CXN44 coaxial drivers and found that they gave quite a nice wide image even when I am at the end of the sofa. I think this is because of the diffraction and tuning the response to work best slightly off axis due to the choppy response a 0 degrees.



SO...

An idea I have been chucking around in my head for a couple of weeks is this:

A more compact floorstander using an SB Acoustics SB15SFCR39 for bass in a vented enclosure, extending further down to the early 20hz with boundary/room loading. For mid and high, the B&C 5CXN44 in a sealed enclosure. Both drivers would share the floorstanding unit, reducing both physical and perceived space.

SB15SFCR39 ≈ 26L / 35hz vented
5CXN44 ≈ 4L sealed

I am totally up for other drivers but I don't want to go beyond 200mm wide baffle and I'm not too keen on a side mounted woofer owing to little fingers.

As discussed here I have implemented a good approximation to a 4th order LR to a Seas tweeter by estimating the existing Q and frequency, and using an LT to raise the cut frequency and make the response align to the 2nd order Butterworth - and then overlaying a further second order.

This gives a pleasing result with my miniDSP crossover.

I'd like to use this technique again - but with a conventional (if external) crossover. Is there any software that would do this, or should I just try to replicate the response by simply fiddling in XSim with trial and error? I don't need to introduce any gain, its all attenuation and raising the cut frequency.

(And yes that leaves me with the Z offset to mess up phase, which I deal with in pure delay in DSP - but it will be a starting point, and for some tweeters with very low Fs, I might still look for around 1.2kHz 4th order - like my Wavecors for example - which should reduce the phase error somewhat).

There are a lot of recommendations to keep the distance between speaker drive units as close to each other as possible, especially the drivers for higher frequency, because a point source configuration is preferred.

Let’s look at these “Avalon” speakers. They are two ways system comprising a woofer and a tweeter per cabinet. But, as can be seen, those two drivers are positioned so far from each other, and work together (crossover point) at high frequency as a typical two-way system. So, does the distance between drivers really matter?

Or, in fact, the statement above is true, but Avalon has applied the special techniques on them. Is there anyone used to reversed engineering these speakers? Could you please advise us what are the magic/secret designs—the special approaches/techniques, e.g., using higher-order crossovers with large overlap, or using lower-order with a lot of EQ circuits including baffle step correction, etc.?

Hi All. I have the 5500 Mk2 tuner that works perfectly and sounds good, but every "locked" station shows a frequency of +0.05MHz. QUESTION, is this just a case of the frequency counter of the display needing a fine adjustment or does more complex adjustment need to be done? I realise it would benefit from a total accurate realignment, but cannot find anyone in the UK that can do it. If it is just the frequency counter how do I adjust this please? .....Thanks for reading.

Hi All. I just cannot get my head around this BIAS measuring of the L12 Amp to enable to set the bias trimmer! QUESTION: What VOLTAGE should I set across the combined emitter resistors please in the shown example below to achieve a bias current of 40mA? It's a BASIC OHMS Law calculation, but do I use the SUM of the resistors (0.44 Ohms) or just the single value of 0.22 Ohms?. ... In my amp the emitter resistors are in fact just 0.1 Ohms.... Perhaps I should measure each collector voltage separately to ground across it's single resistor instead? Many thanks for your help.

Good morning and happy Monday, y'all! I hope everyone had an excellent Thanksgiving this year. 🙂

Before I get into it, I want to thank Victor Kung @ VKAudio for his assistance and patience in answering my questions, particularly about Capacitor upgrades. His knowledge is invaluable and he's a good guy to have in your corner when you need help. I also want to thank TubeDepot which is where I purchased my kits from. Honestly, if I'd have spotted Victor's store earlier, I probably would have purchased directly through him. However, I have no complaints whatsoever with my transaction as TubeDepot has always provided me with great products at fair prices.

With that done, I'll move on.

I've been an audiophile for more than 35 years. Music is the one thing I can depend on to get me through each day. It make a bad day turn good and make a good day even better.

Now, I'm not an audiophile in the "I own a set of Infinity IRS-V speakers powered by 3 Macintosh Amplifiers" sort of sense. I would love to be there, but that's a financial commitment I'm simply just not able to justify. However, I absolutely love how a quality sound system can bring out deep emotions, stir up memories of people and places, and transport you to another time. It has that much influence.

Until recently, I've always been a solid state kind of guy. Part of the reason is that the generation I grew up in was on the leading edge of Transistor technology with vacuum tube well on their way out the door. In fact, about the only thing you could buy with vacuum tubes in the '80s were guitar amps, and even those were rapidly declining in favor of the less expensive, sturdier solid state equipment. I do remember as a younger child, my parents and grandparent having old vacuum tube equipment, and I would spend many hours listing to records on this equipement. This probably set my mental bar for audio quality.

I guess that the other reason I was into solid state was that I was very big into car audio in the '80s and '90s, and there just isn't any place for vacuum tubes in car audio! I see there are companies that actually specialize in this kind of equipment, but that all seems a bit gimmicky. LOL

A couple years ago, I really started getting back into the idea of analog sound. I have always love vinyl and actually had an impressive collection until our house burned down in 2015 and we lost everything. Almost 40 years of collecting lost forever. Anyway, while I enjoy the analog nature of vinyl, it's always been through solid state amplification. Not that it was bad... In fact it's quite the opposite. It's just that I always did feel like something was lacking. Some level of depth or warmth that I remembered from my childhood that I just couldn't seem to reproduce. So decided to start looking around at what's available.

Vacuum tube audio equipment is clearly big business these days, with companies building preamps, amps, active crossovers, and other stuff that vary in range from hundreds to hundreds of thousands of dollars. The array is as dizzying as it is almost endless. Reviews leave you with more questions than answers, and almost anything with decent reviews will empty your wallet in short order. But the question at the end of the day is, "Is a $10,000 amplifier any better than a $1,000 one?" I'm sure that at the end of the day the answer would be, "Yes, the $10,000 amp is better." But the next question would logically be, "Is it $9,000 better?" In many cases the answer would be solidly, "No."

With this in mind, I started looking at many different amplifiers in the "under $5,000" range. There are a number of what I presume to be quality products on the market in this price range, but still couldn't make heads or tails of what was actually worth dropping my hard-earned cash on. Oddly enough, while researching different amplifiers, I came across a DarkVoice 336SE headphone amplifier in a pawn shop and scooped it up. Even before I plugged it in and turned it on, I was already looking at reviews, schematics, and upgrades to this unit. My first 20 hours into it, I had already order a variety of tubes so that I could start rolling as time permitted. I do realize that this little amp met with mixed reviews, but was mostly positive. I also discovered that there were some very easy improvements that could improve the quality and reduce the idle noise of the amp. I, personally, love this little amp. It brought back that sound I so vividly remember from my youth. The depth and presence that I felt I was missing was restored. Even with high quality digital recordings, there was a sonic improvement. That's was it. I'm now hooked on tube amplifiers!

I figured the best place to start would be at the bottom of the chain and slowly work my way up. After digging around for several months, I came across the TU-8200R Amp kit along with the TU-8500 Pre-Amp kit. I found it intriguing as it was a full-on, build-it-yourself sort of kit that came with everything. The reviews on it were outstanding, and the documentation on component upgrades was well defined and easy to follow. The only pitfall was that some of the upgrade components were no longer available, such as the AMTRANS components, but c'est la vie. The biggest improvements seemed to come from using Mundorf coupling caps and Lundahl transformers anyway, so that was what I opted with for the final build. Tube rolling will come later. Ordered through TubeDepot and then waited for the brown Santa to show up in his trusty delivery van.

I did my process a little backwards, starting with the pre-amp first as I was waiting for my Lundahl transformers to come from VKAudio. Out of the box, this thing is a solid work of engineering. The chassis was remarkably clean in design and fit together well. I may, at some point, disassemble and have the chassis powder coated a different color, but it's great as it is. The PCB is laid out very well, all the components were grouped in nice, organized baggies, and the instructions were very clear to understand. Now, I'm an electronics engineer by trade (digital, not analog), so following a schematic and PCB layout is a simple thing for me. Not to mention that I have a helluva soldering station. PCB assembly and soldering didn't take long, and within a couple hours I had the whole thing put together. Slapped in the J/J tubes, connected my Technics 1200 turntable to it, and hooked it up to an old Pioneer SX-980 with Kenwood KL-777A speakers and then let 'er rip.

I let the pre-amp run for about 2 hours just to let things settle in and then dropped Tom Petty on the platter. Even with the tubes barely even run, the difference was immediate. The sound was warmer with vocals that were more in the foreground. I played this album and then moved on to my next favorite, Pink Floyd - Wish You Were Here. Shine On You Crazy Diamond (Parts 1-5) is my quintessential sound system test. For me, this track reveals the soundstage and depth of a sound system, or even the capability of individual components, and let me tell you, the TU-8500 did not disappoint. I went with this setup for several days, and with each passing hour the pre-amp continued to provide subtle improvements in sonic and tonal quality. I now realized I needed to get the amplifier built!

Thanksgiving intervened and I had to do all that family stuff. While I always enjoy being with family, I was quietly preoccupied with wanting to put the amp together. Our office was closed for Black Friday so I headed in and began the process of assembling the amplifier in peace and quiet. Again, all the details were impeccable and assembly was completed in a matter of hours. I'm a bit of a perfectionist, and since the tubes are exposed in this unit, I spent a little extra time making sure that the tube sockets were level and even. Unfortunately, during my final assembly of all the PCB units, I forgot to solder the bridges on the bottom of the input/output board which left me a little perplexed when I fired up the amp and had no sound. A few muttered curse words and 45 minutes later, all was good.

I've always heard from people that 10 watts of power from a tube amp is like 50 watts of power from a solid state amp. I always took these comments with a large degree of skepticism since I've always argued that "Watts is watts." I guess that it's true that wattage is a pretty stable measure of audio output. But let me tell you right now... This little amplifier that only runs 8 watts per channel sounds better than my 100 watt per channel Onkyo receiver (in stereo mode) running through a set of B&W 603 S2 speakers! Of course, the Onkyo running in 7.1 will simply outmatch almost any 2 channel amplifier for range and soundstage, but in 2 channel mode I would take the little tube amp every time. There is no absolutely no hint of hiss or hum at idle with no input, even with headphones on. It is dead quiet until you feed the signal back into it and then it just fills the room.

I just couldn't believe the quality of the sound the TU-8200R produces at a pretty solid listening level. It's certainly loud enough that I can feel immersed in the music, and that even with the TU-8500 pre-amp on a flat 1x gain on the inputs. I haven't even turned it up to 3x yet, and from what I've read so far, the amplifier can certainly handle the higher input levels without becoming too distorted. I may give that a try tonight and see how well it handles. I expect it may pick up some signal noise, but I can't say until I give it a spin.

As an aside, the amplifier works great with a set of high quality, high impedence headphones. My Sennheiser HD-650, which works fantastic with my DarkVoice 336SE, sounds fantastic with the TU-8200R. Of course, you don't buy an amp like this just to plug in a set of headphones. It's just nice to know I'm not losing anything in sonic quality. My DarkVoice picks up stray interference with the volume turned up and no live signal coming in, but I think that has more to do with being pretty close to my monitors on my computer desk. I've moved it to another location and that noise disappeared. However, I do not get any noise with this combination of pre-amp and amp sitting in the same location, so the DarkVoice might need a little more input filtering. I did install the PS-3249 DAC module and that works just as I would expect. I don't expect to use it much, but it's there if I need it and it doesn't take away from anything when it's not plugged in.

Overall, this has been an absolutely fantastic kit build. It's a pretty easy go, provided you have a resonable level of skill with soldering. The rest is just following instructions. I did take the amp apart and installed the original transformers just for a quick listen, and the sound did have a little bit of dryness to it. I can't quite explain it, but it felt like some of the low frequencies were a little muddled and washed out which took away from some of the depth of the soundstage. I can't say for highs since I have tinnitus (too many years of concerts and loud car audio) and can't hear anything above about 12,000 Hz, but the range I can hear still seemed to be pretty clear and sharp.

Tube equipment is clearly the way I need to go in the future. I got my feet wet and I'm now ready to jump in. Just for grins, I've already ordered and received the TU-8550 pre-amp and will soon order the TU-8900 amplifier. I'm ejoying the building of these kits and have been absolutely floored by the sound quality of both the pre-amp and amplifier. I mean, for the price you just can beat it. And with the ability to swap power tubes in the TU-8200 between the 6L6, KT88, EL34, 6550, and possibly even the KT90 (I don't know if KT120 would work), all with auto biasing, it makes tube rolling a fun (albeit potentially expensive) adventure. But if you're going to tube roll, then this is a great way to start out.

Again, many thanks to Victor Kung, TubeDepot, and also to Elekit and the infamous Mr. Fujita. Excellent work by everyone in bringing this exceptional product to market and making it affordable to the average hobbyist. It provides entry level access to quality tube audio equipment as well as a platform in which to build a solid foundation of understanding how tube audio equipment works. Well done!!!

TL;DR

I bought the Elekit TU-8200R amp and TU-8500 pre-amp kits along with Lundahl transformers and Mundorf caps for the amp. I assembled them and they are *******' AWESOME! Do yourself a favor and get these for yourselves. You can't beat the quality, especially for the price.

Hi gents, I am a new to the group.

Hello

Currently I am trying to design and build prototypes similar to danley BC218, divided in half for easier transport and multiple possible deployment configurations. I will be using 18SW115 8ohm version as i already own them and it seems Danley also uses them a lot in his designs. My goal is not to make a identical copy of his design but to make a sub with similar preformance and same design benefits. Aiming for same dimensions and about same frequency response (-3db@ 28hz).

I've been following @weltersys folding prediction and made a 3d model, but 18SW115 sadly doesnt fit and i am not exactly sure how to model in hornersp with decent accuracy.

I am relatively skilled in Solidworks, Catia and cabinet building (designed and built my own version of TH118 and 4 way synergy horn), but lack experience for simulating such advanced horn sub.
Any help would be appreciated, as i said looking forward do design 3d model first from usable simulations, then build 2 or 4 prototypes - I have a huge free area near my house and I will keep this thread updated with build progress and measurements.

Looking for support in simulating this folding or exploring possible different horn foldings

Attaching picture of a very rough model

I own 2 atmos avrs and find both disappointing. IMO, height sounds such as aircraft, birds, thunder, rain, wind, spacecraft, rocket and other height sounds should only come through height speakers. Atmos is overhyped and basically snake-oil. There's no unique content in the heights. It's just a replication of the bed layer channels. Manufacturers are no longer making bluray players, because physical media is dead. Everyone is streaming. But streaming has a bandwidth problem. You can have quality 5.1, or compressed & lossy atmos. Since the heights are just the same data repeated, it makes sense to save the bandwidth and do the replication in the avrs instead.

I also want to boost the bass only for gunshots, thunder and explosions, and not music. And have automatic attenuation.

These are my goals...

Hello all! Came upon a Crown DC300A. Bringing it back to life.

I was thinking about replacing the motor in my TD166 MkII with a brushless DC motor. The main aim is electronic speed adjustment to replace the mechanical belt-shifter.

Has anyone tried this? I did find the Origin Live and would like to built my own "cheaper" version of that.

Was thinking of using PWM speed control, possibly with hall sensor. Or an Arduino-based controller.

Can use soft-start or keep the original clutch-pulley

Is this a good idea? I would appreciate any advice on the best motor/pulley to use and reliable speed controllers.

Alternatively; let me know if it is a stupid idea and that I should just leave it alone 🙂

Good afternoon. After ordering a qcc5125 + es9038q2m + NE5532 board on aliexpress, a problem arose. In general, the board gives me good enough sound for me, but there is a nuance. After I stop the sound from Spotify, there is silence. There is no sound in games, no sound in Discord either. I saw that this is a problem with the firmware of the Bluetooth module itself. Can I reflash it? I'm not a handyman, but I don't have very deep knowledge of electronics. Is there any way to fix it? I'd be very grateful if someone could throw a link to the instructions or write how to fix it.


Module: link

Hi Folks,
I have been getting a lot of inquiries about a possible Flatpack for the popular 10F/RS225 FAST TL speaker. There have been probably 50+ successful DIY builds of this speaker. Everyone is a very happy with how they sound. I have developed plans for a CNC cut flatpack of this speaker in 18mm birch faced poplar plywood (Trueply brand). The design will include a lot of 6mm alignment dowels for easy assembly with glue and clamps. The dowels prevent the boards from squirming under pressure and ensure a straight and well aligned speaker box with true 90deg corners. More info on this speaker can be found in this thread. The crossover PCB can be purchased here if you don’t want to build your own P2P XO.

Here is what the plans look like:

Very similar to the released plans that folks have been building to and uses a trick first seen on member @Plott ’s build for the baffle (stepped edge).

The pricing will be $575 a pair in birch faced plywood. And $675 a pair for walnut faced plywood. Examples of the plywood can be seen in the XSD Flatpack GB thread. It’s nice stuff used for furniture. User will need to provide drivers, foam padding, stuffing, binding posts, and sports cone rear chamber for the mid tweeter. We will provide the 50+ 6mm x 30mm wooden dowels per speaker.

Shipping in CONUS via UPS will be typically $150. There is a service for shipping to EU for about $250 from the port located in NY/NJ area to most places in EU. So about $400 total to ship to EU. You will need to check with the provider.

Here is a photo of Plott’s build which I think will look very similar to this GB flatpack.


In case you are not familiar with this speaker, it is a transient perfect design with superb imaging and time alignment for crisp percussion and the TL reaches deep to 28Hz so no need for a subwoofer. The sound is balanced, neutral and great for any genre and is never fatiguing. It has been my main speaker for the last 5 years. And I have seen and heard a lot of speakers.

Schematic of XO:

Here are some in room measurements (2vrms at 0.5m) there are some room modes that cause a dip near 120Hz but that’s not intrinsic to the speaker. You can see the reach of the TL bass and the smoothness of the reponse and the overall low distortion.

Here is response of the woofer TL output at exit plane of the vent to eliminate room modes. You can see the output is smooth and flat and reaches down to 30Hz easily.


Here are some measured impedance sweeps showing it is an easy 8ohm load and that the TL is tuned to circa 28Hz to 32 Hz depending on your driver TS parameters and stuffing placement etc.


If you are interested please add your name to the interest list below. The flatpack allows those of us without the woodworking shop or skills (like myself) to have a great speaker like this.

Name / Birch or Walnut/ Country

We will need at least 5 pairs to make the GB viable.

Thanks.
X

hi. i am trying to setup a thomson dpl 550ht sound system at a friend. the analogue input works fine as well as the radio.
unfortunately when trying to play via optics: tv -> receiver i have a no sound issue.

Any idea why this does not play? I tried manuals an everything but nothing helps.

Is there a way to reset this device? could not find the correct steps.

Please help!

ps: i have no remote.

Hi all,
DSP seems to have endless possibilities. What I am looking for is - a high end quality - DSP which can be freely programmed as a 2 X 3 (or 4) way crossover,
which then can correcting all individual speaker units, eg woofer in closed compartment, phase correct (ing) for phase shifts and room correcting.
Does this exist? PCB's or complete devices? Most if not all searches return MINI-DSP, why "mini"? Then some have digital inputs only, I think I need analog input.
Oh why isn't here a DSP thread other then the MINI-DSP?

I have a bluetooth speaker that has started producing extremely loud sound. When the speaker is turned on and makes the "on" sound it is extremely loud to the point the drivers are clipping. When playing music even on the lowest volume it its clipping, distorted and extremely loud. It seems it is more the low frequency gains are high, the tweeters dont seem to make much sound compared to the extreme loudness/clipping of the drivers.

Any idea what causes this? Have never seen anything like this before

I was leafing through Self's book and happened to come across the chapter about output inclusive compensation. It intrigued me, so I tried to try it on the amplifier I happened to have open in SPICE and it improved both phase margin and THD. The THD went from 0.00077% to 0.00035% (no, it's probably not an audible difference, but improving your numbers is fun!). More notably the decrease in THD was most pronounce on the third harmonic. This seems like evidence of Self's assertion than this semi-local feedback reduces cross-over distortion. All good stuff!

But what are the pitfalls? I can't remember seeing this technique being used that often. There must be a reason for that.

The compensation in question is made up of C6, C24 and R52. The amplifier is work in progress, so be nice. 🙂


The phase margin looks pretty nice!



Distortion without output inclusion. Notice the 3rd harmonic!

IMG_20210108_171719.jpg - Google Drive

hey guys its a google drive link but i basicly had this unknown 18inch driver that needed a repair ti the tinsil leads and finaly did a box for it the box was aimed at 13 cubic feet to be tuned at 35hz it sounds alot diferent to my other ported boxes as this one has an internal l port and doesnt seem to a wide a bass frequency as my others but its running at 90hx off a electronic crossover and have a good 600watt to feed it

but need to move things around a bit because halfway its makeing my cd in my luxman cd player jump

Even though I heard about exciters few years ago, I never took them serious as hi-fi , standalone loudspeaker option.
Looking at various videos on YouTube just confirmed my initial beliefs:
- typical DML video always showed different enthusiasts, often playing with XPS or various other similar soft insulation materials, trying various surface treatments, various methods for exciter mounting, suspension, etc. but in the end, sound quality that these DIY creations produced was far away from hi-fi quality.

One thing they had in common - they all lack bass.
Event though some of them could reach lower than 100Hz, the bass produced didn't had sufficient authority, so they all required additional subwoofer to reproduce lowest octaves properly.

So I almost dismissed idea that high quality DML system could be created, until I started to read "DML full range study" thread.
I read that thread for a long time, and at one point I finally decided to play with exciters, to see their full potential
as full range , high quality loudspeakers.

Anyway, I purchased my first exciters=> "Xcite" XT32-4.
After I install them for first time, I was surprised by all the usual good sides of DMLs:

• Extremely wide dispersion,
• Clean sound.

The panel was about A4 size, 3mm thick, consisting of a cork layer with glued hard plastic backing.

But as I didn't play with DSP, the frequency curve was way off, there was no bass, and I stopped with experiments for a few months.
So nothing was happening, and I was idling until one day I decided to give DMLs second chance => this time I used large piece of dibond composite panel (about 800mm height and 600m width),
installed two XT32-4 drivers on single panel, and hanged the whole panel on thin elastic strings.
I secured both drivers to prevent movement and connected each driver to one stereo channel of my smallest bluetooth amp (2x6W RMS !).

Without DSP, this panel sounded considerably better, but still not perfect so I used equalizer, performed couple of REW sweeps, and after couple of days, the sound coming from this single panel was impressive - I couldn't believe that
single piece of panel could sound so good => it had all the benefits of typical open-baffle sound (like my home speakers), but with extremely wide dispersion.
Here is the video link to one test song : Login to view embedded media
Then I played all kind of music for a few months, to find good & bad points, and I concluded that DMLs indeed have potential as hi-fi standalone speakers, though they still have to be refined, especially if I want to reproduce lowest octaves.

What was strange at that time, most of DML enthusiasts discussed how panels should be attached to frame, at couple points, if you want good bass reproduction.
My thinking was totally opposite - I should have sufficiently strong panel, and then I should enable maximum panel movement , to have largest stroke possible, if I want to have good low frequency reproduction.

So I decided to go against the flow - I decided to make relatively small DML panel, with large stroke, that should have following specs:

a) Standalone speaker design,
b) Panel will be mounted vertical, but with hidden frame & hidden suspension,
b) Single composite panel (910mm height x 320mm width),
c) 2-way design (one exciter for bass, two exciters for mid/high range),
d) Soft suspension (to enable more than +/- 5mm stroke),
e) Two stereo amps, with integrated DSP : 2 x 120 W for bass exciter, 2 x60 W for mid/high range.

After couple of months, I completed my prototypes, and then I spent few days with REW to finely tune DSP.
The final result is that I could reach 35Hz (-3dB), in my small office, and that for the first time I could hear and feel bass from DML panel, without any subwoofer.

Here are some demos - first is a YouTube video , with four different songs (jazz drums, two songs from "Gladiator" movies, and two choir songs):

Login to view embedded media
If you listen first song, check sound of kick drum - it is quick, goes deep, and is very well defined => I stil couldn't find similar bass reproduction from any of the DML YouTube videos yet.

(NOTE: sound was recorded with "Tascam" DR-05X digital recorder , in 24bit/96kHz quality.)

My friend Arvel is working to repair a B&O TX-2 turntable with an exotic, and somewhat intermittent issue that I'm unable to help with. This machine has a dual solenoid with uPC control that triggers several gap-toothed gear wheels for arm lift, arm start/stop, etc. The observed issue is a chattering of the solenoid and its lever controlling the 1604 cam's gap-tooth segment, causing intermittent operation. He has experimented with various lubes and various spring tentions, even with gear teeth profiles from a donor unit, but without really reliable results.

I have the service manual (actually two, wretched excess is the American way) and can post scans, but I suspect this is so exotic that only someone who's actually seen and solved the issue might have insight. Goes without saying, all the obvious issues of the solenoid drive electronics (all electrolytics replaced prophylactically, yada, yada) can be ruled out (But! Never say Never).

A Hail Mary pass, in case anyone might have seen this, and thank you,
Chris

As I have two pairs of these drivers for surround loudspeakers purchased some years ago I was looking what others have done with these 15 euro fullranges.

Now I think about what to do with them (no surround sound system at the moment).


Here information I gathered on this one

TQWT

http://leoandfanny.bplaced.net/loudspeaker/joe.html

https://zelfbouwaudio.nl/forum/viewtopic.php?p=1777196&hilit=senon#p1777196

Open baffle

https://zelfbouwaudio.nl/forum/viewtopic.php?p=1569529&hilit=rockwood#p1569529



specs speaker:

Senon/ Rockwood DY - 811U

Qts=1.7
fs=95Hz
Vas=9.8 ltr
Qms=5.72
Qes=2.42
Re=7.0ohm |geschat
Le=0.31mH |geschat
mms=17.4g
BL =5.47Tm
sD = 0.0208; |Membraam oppervlak m2

Spl: 87 db toegevoegd

Hello, today I built my first DIY amp with an LJM L15 and when I switched it on it exploded, this came as a surprise as I had made sure that the output voltage from my power supply was ±55 V I had also triple-checked my wiring to make sure that I wasn't plugging the VCC and VEE in wrong. I am planning to buy a new pair of L15s to retry this build, but I want to know what went wrong. I've attached a coupling schematic and pictures of which transistor blew on one channel and where the PCB burned out on the other.

I have found the lowest frequency response for the dome midrange drivers, in my life, to be 350Hz. This is from a commercial speaker; ADS L1590, where its dome midrange driver is only 2” (50 mm.) diameter.

By the way, considering high-pass section of the bandpass filter used with these 2” mid-domes, the manufacturer—ADS—use a 33uF and a 2.6mH to form a second-order filter for them and commonly use in all models equipped with these 2” drivers in L series 2 speakers e.g. L880/2, L980/2, L1290/2, and L1590/2, etc. This combination results in 550Hz cut-off frequency. And the various crossover frequencies are varied by the low-pass filter of the woofers, according to the picture below.



Has anybody ever found any lower frequencies?

Besides these ADS’s domes, there are modern brands that sell dome midranges, however, I’ve never seen any with lower than 550Hz capable, even though it has larger diameter, such as a 3” Vifa, etc. A Dynaudio D54 has about 2” diameter too, but the spec sheet recommends usable frequency in 700-7,000Hz range.

Why no manufacturers make the dome midrange that could go below 500Hz, except ADS?

As title sez - one name, two preamps.

Tanka SE, logically, being for single ended signal arrangement, so 5 RCA inputs, and one RCA output; I'm usually mounting doubled RCA outputs, wired simply in parallel.

Tanka (no suffix), balanced signal configuration, any number of 5 inputs can be arranged as (permanently) SE/RCA, balanced output can be wired to one or two (parallel) XLRs, or one XLR and (parallel) RCA

Tanka is is nothing else than tubed** Irreverent, which is nothing else than unnecessary complicated Fancy Iron Pre, having all the bells and whistles on board (big one), with integral 128 steps resistive attenuator, governed with little Arduino Gizmo and there is shiny TFT and heavy remote.

Dazzling, Shiny and Overwhelming characteristics speech: Fully dual mono, ultragigamega shunt regs, OhYeah! Gloving Toobz serving in buffers, precious Fujitsu relays for everything what's switched, volume attenuation constant Rin 24K, 128 steps of 0.56db each, ranging from -71.7 to 0db, and then (whadasurprize) autoformer (Cinemag or Jensen or Edcor repeaters) gain, settable to either +6 or +12db, yadayada.......

Button on front, fiddle left-right to set volume, push for incremental cycle through inputs 1 to 5.

**Tube-mosfet compound buffer, instead of same-sex-JFet buffer, as in Iron Pumpkin, Irreverent

Toshiba TA8233H fully built chip amp 30wpc BTL stereo

Designed & built by polish enthusiast Fryderyk Wrobel (FRD1996) based on Toshiba datasheet circuit diagram compete with generous heatsinking & all cables soldered into the board for power, input & output and including a pair of russian military matched output capacitors (see detailed pix)

The TA8233H was originally supplied to the automobile market and it will run on any DC PSU in the range of 9-18 vdc including of course 12v car battery

The TA8233H chip amp is highly regarded especially in Polish hi-fi circles and this is a great simple well-designed board, for anyone who wants to give it a go. only used once to test it working. part of a larger project that never came to pass

These chips are now somewhat difficult to find new (as this one is) with most pulled from used equipment

Looking for £40

Would prefer to post only to UK. Royal Mail 2nd class small parcel cost of £3, but pleased to use more secure service for royal mail cost

Thanks

I'm searching for a little 2-way amplifier like the Fosi BT30D Pro but with a higher bass crossover. I'm curious if there's anything out there in this small footprint with a higher crossover than 300Hz, so that I can use this little cheap amp to drive two mid-high CD/horns and a modest mid-bass woofer. I was hoping to crossover some horns around 600-800Hz, using the amp double-duty as crossover. (This is for an installation on a budget.) There must be dual amp-crossover options, right? I see the Crown DSP amps and Hypex Plate amps, but those seem a little overkill at the moment.

Please see photos below. Shipping from PA 18951 - not incl. /$TBD, either USPS or Fedex. PayPal only.

(qty)
(8) Panasonic HGC FA - 22,000uF / 100VDC / 105C - $12 each or $80 for all 8 (NOS/surplus - never used)

(3) Nichicon KG(M) Super-Through - 15,000uF / 50V / 85C - $10 each or $25 for all 3 (new)



Thanks for looking! See my other listing for film capacitors

I have 3 4' x 8' of 3/4" inch Sonopan II sheets given to me from my neighbour who finished a drywall install. I thought I would take them and try and make some simple acoustic panels for my 8'x20' foot room. I'm trying to do it on a small budget and weighing in if I should just scrap the idea and buy some of the cheap foam 12" square foam tiles from Amazon. The problem is that looking at the reviews some of the panels look kinda deformed and "tacky" looking. They are not a cheap option to cover a large surface area.

I thought of the idea to cover the sonopan with a cotton or canvas drop sheet for painting. I am not sure if I am any further ahead messing around trying to make them look good enough and if I put them on the walls will they even work? There seems to be a difference between sound proofing and room treatment to reduce sound absorption and the Sonopan seems to be marketed for insulating rooms bolstering modern constructon materials such as sheetrock/dry wall.

I wanted to take some baseline measurements with REW before I start messing around with the stuff. I am waiting for a calibrated mic but I wanted to ask the question because my room is rectangerlar with 9 foot plaster ceiling so I am looking for easy ways to remove the "live" aspects of the room. I have started with added area rugs which I feel improved things quote a bit but I am going to add a couple more. As for the walls my front wall is my projector screen so I can't add anything there. I have a large window on the right side that is 70" x 35" I thought I may cover it with sonopan to keep the area dark and to add some absorbing qualities or to make it a little nicer looking add the foam tiles on the window. I don't use it for anything and it could remain sealed. My rear wall is another place where I imagine needs treatment. It is just a large dry wall space about 8' x 9'.

Has anyone worked with sonopan and have any good and easy traps or panel designs? I am sort of interested in using it as I already have it. I know some people use a combination of rockwool and sonopan. I really want to avoid having to cut wood and make frames.

Also -- my speakers are rear ported. Is there anything to anything to gain by putting the Sonopan sheets behind the speakers flush to the the floor. That would not impact my projector "screen"?

Let me know your ideas and suggestions.

JD

Hello, here i would present and discuss my new Speaker Design stepp by stepp.

At the End i will use aktive Elektronic for Crosover.

But also the Use of an passiv Crossover i will show you.

My first Step is already done.

The Design off an Waveguide for my Harwood AMT25.

https://www.diyaudio.com/community/...-cnc-3d-printing.318190/page-127#post-8023326

For the Midrange Speaker i will Use 2x Scanspeak 18W8434G00 Parallel.

I used the AMT 25 already in an 2 Way Box with an 18W4434G00 (Aktiv Time alligned) and this worked already very well.

For an MTM Kombination i need an deeper Crossover Point so i decided to build the Waveguide for an Crossover Point Between 1800 and 2000 kHz.

Next Step was to find Out how an MTM Measurement looks like Vertical and Horizontal.

For the first Approach i used my build 2 Way Speaker and put them together:



The Distance between the Middriver here is around 261mm Center to Center

Vertical i Measures This Way:



And here how it looks (Red line Microphone @ Point A, Green @ Point B):




Here the same Measurement with an greater Distance between the Middriver:



And the Measurments (Red line Microphone @ Point A, violet @ Point B):



Verticaly it is bettter to have the Driver Close togther, spcialy for an Corsoverpoint of 1800 to 2000Hz! I would say.
On the other Hand on a DAPOLITO Box you realy need to have youre ears @ the hight of the Tweeter for best listenning expiriences.
If you can sit, let say 3-5M away from the Box thats is less Important i guess.
But my listinig Position is in between 2,5 to 3M so i need to have the Hight of the Tweeter @ around 80cm from the Ground.

How i measured it Horizonta (Distance MTM 384mm Center to Center for worsed case scenario):



Here you cac see the Horizontal Measurings magenta 0degree, red 25degree and black 40degree:



So i would say Horizotal i could easy use an 2 kHz Crossoverpoint, Verticaly its more difficulty.

I have here for sale this NOS darlington output devices from ST, I can sell in pairs or only the NPN device,
because I have more units of the NPN device.
Price for complementary pair is 10€, or I can supply just the NPN device at 4€ a unit.
Payment by pp
Regards

I have here for sale severall capacitors from Elna new and used.
1-Raw
Used Elna Silmic 12000uF 63V 20€/unit or all 4 for 60€
Used Elna for Áudio 10000uF 63V 12€/unit
Used Elna for Audio 10000uF 63V 12€/unit
2-Raw
Used Elna Silmic 5600uF 63V 10€/unit
Used Elna for Áudio 10000uF 56V 10€/unit
New Elna for áudio 10000uF 25V 5€/unit or all 6 for 24€-sold
3-Raw
Used Elna for áudio 3900uF 63V 5€/unit
Used Elna for áudio 3300uF 35V 2,5€/unit
New Elna for áudio 10000uF 25V 5€/unit or all 6 for 24€-sold

New Elna RSE 2.2uF 50V 20units per lot at 10€,10 lots available(200 units)
I can sell the whole lot together for 200€ "230 capacitors"
All used capacitors here for sale have been measured and are within 10% of its rated capacitance
Regards

Hello friends,

Wondering if someone could have information on this unit. See picture below. The only identification is the 77235 which I assume is a model number since it is the same on the two units I have.



No information about this on current Hammond catalog, but physically it looks like one of their "broadcast quality" units. Transformer is in sealed case, looks rather vintage from the ancient Hammond logo style.

The soldered pins strongly suggest dual windings, and winding pairs from each side are isolated from the other as you one would expect. Measurements are:

• Pins 1-4 : 59 DCR, 3.27H
• Pins 5-8 : 46 DCR, 3.3H

The slight inductance difference is probably a tolerance error from the cheap LCR meter I have on hand; so that is probably a 1:1 / 1:2 "line to line" matching unit.

If people have links to catalog archives that would be good too; I found a 1965 and 1974 catalog but no other meaningful results. Hammond's series and model numbers don't seem to have changed much in time so there's a possibility that maybe an OEM job - I don't know the origin of the transformer.

Thanks in advance for any help

An illustrated guide to building the Aleph J

This is a guide to building the Nelson Pass / Firstwatt 'Aleph J' amplifier.

A few links to start off -

Aleph J Manual (From firstwatt.com) http://firstwatt.com/pdf/prod_aj_man.pdf

Amplifier PCB (From DIYaudio) Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards

Discussion thread - Aleph J for Universal Mounting Spec - diyAudio

Bill of Materials (BOM) - diyAudio

Schematic -



Ok!

The bulk of this guide is going to show the green PCB, which were proof-of-concept prototypes. The boards worked great and we needed to make very minor changes to the production boards, which are blue. There is effectively no difference between the prototype and production boards. Also worth note, the photos of the PCB will be from two different builds, mine (6L6), and Grimberg's. There are no significant differences in how the PCB was stuffed or utilized. I think Grimberg did a prettier job stuffing the PCB than I did. 🙂

Also, this build will show a 5U 'Big Amp Chassis' from the DIYaudio store. (Because that's what I have on hand.) The Aleph J can be made into the 4U 'Jack of all Chassis', everything will fit and the heatsinks are (just) big enough. All the specifics surrounding the 'premium' chassis (back panel, perforated base, pre-drilled heatsink, etc…) are functionally identical, the differences between the 4U and 5U are mainly just size. Regardless of the chassis you use, this amp does get quite hot, and good ventilation will be required around the entire chassis.


On to the guide.

Here is the PCB. It's a great layout, please thank member Didiet78 for his work making this. 😀


Front


Back


Stuffing the PCB

The normal order of operations is to do the little things first and place the bigger things as you proceed.


This PCB has 4 connections that are normally going to be jumpers. (R6, R30, J1, J2) You can see them here. These connections can be jumpered with little bits of wire or cut-off resistor leads, your choice.
These 4 pads are there in case you need to add some resistors in case of oscillation, which may happen to some builds. It's rare, but if you need it, there is place on the PCB to add some compensating devices.


R27. SEE TEXT

Let's talk about this - as it is somewhat confusing.

There are 3 places for R27 on this PCB. The first is the pad next to the cap C2. (in the above photo it is empty) I suggest making that one a jumper.
Where the jumper is placed in the photo should be open, and under the green insulation you will find the place for a pot.
SO - place a 100K pot where the pot will fit and jumper the vertical 'R27'. Set the pot to 68K before you turn the amp on the first time.


Here you can see how the pads for the pot are arranged - (underneath where it says "LTP Bias" and similarly under "offset")
The small oval pads are where the pot connects. The larger round pads outboard of the silkscreen are for a resistor if you choose to put it there in lieu of the pot, or can be used to measure across the pot in circuit. Cool, huh?

Also, it does not matter which of the center pads you use - some pots have all three pins in a row, some have the center pin offset. Either type will be fine.



Add the resistors. Shown here are big-bodied Dale RN60. If these fit, and they do, most other resistors will as well. Use whatever parts suit your fancy.





Now add the bigger (3Watt) resistors. It's a good idea to leave some room between the PCB and the body to let air circulate. As shown here -






The best advice I can give you is this - measure every resistor before inserting into the board.


Continue on with caps and the small transistors





Eventually the board will look something like this -


For reference, know that the Power Mosfets (obviously not mounted yet…) on the Left side of the PCB, near the electrolytic capacitors are for the Constant Current Source, and the Mosfets on the Right side, closer to the red input film capacitor, are the Outputs.



Note that in this photo, the vertical R27 is jumpered, and there is a 68K resistor in the horizontal spot. I later replaced the resistor with a pot.


Here is the pot in that position. I used a single-turn because I had one on hand... I strongly suggest multi-turn pots on all of these projects.

Yes, have my LED colors reversed. The V+ should be red. I've even had it marked backwards in the schematic. Lol. 🙂 You could make them all blue, this is a Pass amp, after all… 🙂

The LED on the PCB are there to show that you have the rails connected and the amp PCB is getting voltage. If you want to extend the leads on one of these and make it a panel light, feel free.






Power Supply

The power supply for the Aleph J is going to follow the basic pattern of the Pass/Firstwatt DIY amplifiers. Please look at the following schematic --


The basic topology is this. 18+18V transformer, of at least 300VA, CRC filter with 8 15,000uF 25V capacitors and 8 (4 per rail) 0.47ohm 3W resistors.

May you use a transformer with more VA? Yes, of course.
May you use larger Capacitors? (more uF) Yes.
May you use capacitors with a different voltage rating? Yes, as long as you have 25V or more. (25V, 50V, etc…)

Remember that the factory Firstwatt amps use 300VA transformers and (8) 15,000uF 25V caps. If that's good enough for Papa… It should be good enough for you. But almost everybody makes it bigger. No problem at all. It's easy, so you might as well... 🙂

In this build I am using the old (smaller) DIYaudio PSU board. This particular one has no blue soldermask on the top of the PCB. It is otherwise identical. The section for the discrete diode bridges has been snapped off.


IMG_0822 - My Photo Gallery
Here shown with the Filter resistors (0.47Ohm, 3W, light blue), the Bleeder (2.2Kohm, 3W, dark blue) and LEDs.

For some reason I can get the LED color correct on this PCB… Red for V+, Green for V-


The PCB can accept (8) caps with 10mm lead spacing and 30mm diameter, or (4) of 35mm diameter. These are 33,000uF 35V Panasonic T-UP series caps.


I prefer to use diode bridges in these monolithic blocks.




Bridge connections.






IEC inlet.






120V AC wiring shown - this is the primaries of the transformer. AC will attach to the center terminals.





You are free to comment or question. 😀

Using an Outdoor Volume-Control as a Guitar-Speaker Attenuator

To get better control over the volume of a guitar-amp that’s too loud, instead of spending hundreds on a speaker attenuator, use an outdoor volume-control instead, at a fraction of the cost. Just make sure the control has the same wattage rating as the amplifier. This example is for a 100-watt amp.

Volume Control: Audtek VC-100RO Impedance-Matching Outdoor Stereo Volume Control, 100-Watt, in rain-tight wall-mount enclosure. Available from Parts Express. Part # 300-569. www.parts-express.com $25.98 each.

You will also need some male and female connectors. I used the quick-disconnect type; I call them “push-on” types; the female typically used as a speaker-terminal connector. However, note the size on your speaker. They come in different sizes. Or you can use male and female 1/4-inch phone connectors instead, if preferred. You will also need a few feet of ordinary 2-conductor speaker wire, with one conductor having a black or white stripe, and basic electronics tools, including a crimp tool if you use the push-on connectors. I have tools and plenty of speaker wire but obtained the connectors at Home Depot. They label them “Disconnect F” and “Disconnect M” types of connectors. See examples at Parts Express; part numbers 095-302 and 095-312, but you have to buy in bulk (50 per pack) to order them there.



I have an open-back combo amp, which made it easy to attach the control to an inner side once I had the jumper-wires ready to go (explained below). For a closed-backed combo or amp-head, you may want to use male and female 1/4-inch phone connectors anyway, to be able to patch the control in externally using ordinary speaker cables. But I must leave this for the reader to figure out, since I did not do it that way.

Here are the steps to take to install the control in an open-backed combo-amp.

Step 1. With the amp off and unplugged, pull off the Disconnect F connectors from the speaker terminals and inspect them. Sometimes speaker vibrations will cause them to suffer wiggle damage, weakening the wire at the crimp. If necessary, clip them off and put new ones on, but leave as much wire coming from the amp as possible. You may also need to do that anyway if the connectors you have are a different size (both things are what happened to me).

Step 2. Make two jumpers using new 2-conductor speaker wire as follows. Measure how much wire you need to go from the speaker to where the control will be mounted and cut two pieces of wire; each a few inches over that length, or more. You want plenty of slack, which should be wound up and zip-tied later anyway. [I made my jumpers 2 feet long.] On both jumpers, remove about 1/4-inch of insulation from one end of each conductor and twist the exposed wire strands on each end to make the ends stiff enough to insert into the terminal inside the control (assuming you have stranded speaker wire). On the other end of one of the jumpers remove 1/4 to 1/2 inch of insulation and attach a female connector to that end of each conductor. Then do the same to the other jumper but using male connectors instead. Thus, you will have one jumper with male ends and another with female ends, but with all other ends bare.

Step 3. Disassemble the volume control. There are four screws holding the cover on and four screws holding the circuit assembly to the backplate of the box. Be careful removing the knob; it pulls straight off but is difficult to remove. It can be pried, but don’t damage it. [In my case, I loosened the cover first and used it to pull the knob off.] Hold the circuit assembly by the transformers, not the circuit board, as you work. [Caution! Don’t drop it on a hard floor. And don’t misplace the screws!!!] Also, if you want to keep the box rain-tight, there is a small o-ring under the knob. Save it, to reinstall later.

Step 4. Using the jumper with Disconnect M ends, connect the bare ends to the + and – terminals of either the Left or the Right channel on the Input side of the control circuit assembly (I used the Right channel), keeping track of the terminal you chose for the striped conductor. You will need small screwdrivers, like jeweler’s screwdrivers (Phillips and flat-blade), since the terminals are very small. And you must back the set-screws out quite a bit to get the wires in. I used a Phillips head screwdriver for this, then did the final tightening with a flat-blade screwdriver. That done, tug on the wires to make sure they are being held securely by the terminal. Now you have the jumper with male ends connected to the Input side of the control.

Step 5. Using the jumper with Disconnect F ends, connect the bare ends to the + and – terminals of the same channel on the Output side of the control circuit assembly, making sure to connect the striped conductor to the same + or – terminal you used on the Input side. And here too, once done, tug on the wires to ensure a tight connection. Then you will have the jumper wires with female ends connected to the Output side of the control. Here, I used only one channel, the R channel, which is only rated at 50-watts, because I do not intend to use my amp any louder than that. However, if you need all 100-watts capability from the control, for cranking the amp’s master volume most or all the way up to get an overdriven tone, then you can use small single-conductor jumpers to connect the separate + and – terminals of the circuit assembly; + jumped to +, and – jumped to – as shown in the sketch below. Caution! Continue to keep track of which terminal goes with the striped conductors on each main jumper.



Step 6. Run the two main jumpers from inside-out through the hole in the bottom of the control’s box and then reassemble the control. Temporarily use the knob to orient the circuit assembly how you want it; with the dial’s OFF position (fully counterclockwise) pointing up or pointing down. [I installed the hole and the OFF pointing up, since I do not expect it to rain inside my amp, and I wanted position 5 to point down.] You now have a reassembled control with protruding jumper wires.

Step 7. Fasten the control to the inner wall on one side in the back of the amplifier cabinet, with the jumpers hanging loose. [Do not connect them to the amp or speaker just yet.] I used the left side, and set the control very near the outer edge, to easily reach the knob with my right hand. The control box has flanges with screw-holes for mounting to a wall. Caution! Use wood screws that are no longer than the thickness of the cabinet’s side, so the screw-tips will not stick out from that side’s outer surface.

Step 8. Connect the Disconnect M jumper to the wires from the amplifier, making sure to keep track of which one you chose for the striped conductor. Then connect the other jumper to the speaker, sticking with the same polarity. Turn the control’s knob all the way OFF, then plug the amplifier in, connect your guitar, and turn the amplifier on. After warmup, turn the amp’s master volume control to a desired position, then the speaker control to any position from 25% to 75% and start playing. You should notice quite a difference in the loudness of the amp compared to how loud it was before. Experiment with different settings of both the master volume and the new speaker control to learn how they are going to interact. You may also notice a difference in tonality (such as an increase in treble response) as the speaker control is turned down. For a solid-state amp, you should not hear much of an increase in distortion as the master volume is turned up and the speaker control is turned down. But with a tube-amp, you will be able to get a cranked-up sound at a much lower volume than would otherwise be the case.

Personal Note: Speaker attenuators gained popularity with tube-amp users who wanted to get overdriven tones but without the ear-damaging loudness. OK, but I have a solid-state amp with a built-in processor that gives me any sound I want, including tube-amp sounds. However, it’s way too loud. And the master volume control has dead spots at low settings. But since I installed the new control, I can turn the master up past the dead spots without getting too loud. And I am very pleased.

EOF

WITH THIS >

Male / Female
Up / Down
Left / Right
White / Black
On / Off
Yes / No
In / Out
High /Low
Day / Night

I can't help but think about Polarity.
Another thing about polarity is that it gave us ONES & ZEROS. That is the 'language' of a Computer.
A Silicon switch on or off.

Perhaps the miracle is that if it wasn't for the grains of sand we see on the beach, that is Si = Silicon, todays computers wouldn't exist.

so WHITH THAT ... what do you think?

Cardas 0.22uf 600V x2 $30/pair Used
Russian K72P-6 0.018uf 1000V x2 $10/pair
Hovland Musicap 0.22 600V x4 $12/pair Used,

[Sold]
Audiocap 3uf 200V x 2 $28 Used [Sold]
Russian FT3 0.22uf 600V x2 $15 [Sold]
Russian K75-24B 0.47uf 630V x2 $15 [Sold}

price per pair

Shipping $5

I am looking for a kit which I could build and power with a 12Vdc SMPS.
My usecase is to create a phono digital preamp, where the output of the preamp goes to an ADC module, then to spdif.
I already built it with existing stuff I had laying around: a phono pre from ART, and an ADC module : they are both powered by a SMPS with 12Vdc and 5Vdc output.

I would like to replace the phono pre with a more qualitative one, and I could probably add a transformer (like these TRACO POWER) to convert the 12Vdc from the SMPS to +-12Vdc or +-15Vdc to broaden the scope of the possible preamp kits.

What would you suggest?
I already have the emerald in another setup, and I like it a lot, but it comes with its own powersupply.

Thought it might be interesting to start a thread on a build I am just starting. I'm converting my apogee Centaur Minors to open baffle with active amplification and needed 4 channels of the best I could afford of 20-40W per channel. After looking at a number of alternatives I decided to go with the Modulus-86 developed by TomChr, webpage here Modulus-86: Composite amplifier achieving 0.00018 % THD. and DIYaudio thread here Modulus-86: Composite amplifier achieving <0.0004 % THD+N. - diyAudio. My main reason for chosing this was the fact it provides some of the best measured performance I have ever seen from a power amp (comfortably lower distortion than my source or pre-amp), is unfussy about power supply, working to spec with a basic setup and has a balanced input that gives nearly 90dB CMRR even from single ended sources. Basically reference grade for pocket money and perfect for me as I want to play in other areas with my system at the moment.

A few people are thinking of building this so thought I would start a thread on my build and allow people to answer any questions that they have and share their builds.

What I am afraid I cannot do is offer comparisons with xyz. I've been out of DIY for 20 years and getting back in now so I don't have an array of different DIY boards. Also I am not going to claim that this sounds better than any other LM3886 based amp. It will however measure better, much better and certainly well below any sane levels at which transparency is defined. It should have no sound its own.

I'll take some initial pics and start soldering in the morning.

Disclaimer: I have no financial or other interest in the work Tom does. I'm just a customer.

Hi, community.

What would you judge as the best (premium, but still somewhat affordable) 1" exit throat compression drivers of today? Along with a compact horn that would fit in a normal living room compatible speaker - meaning around 8" diameter max.

My first candidate pair would be an 18Sound NSD1095N on an XT120 horn. Probably hard to exceed that actually, according to its excellent Voice Coil test.

Regards
Stoneeh

This tutorial is designed to get you started and tweaking a decent crossover… whether you're new to crossovers, or have built speakers before and are looking for a design method that relies on listening and doesn't require measurements.

The acoustic concepts apply to an active or passive crossover, since the needs of the speakers are the same in both cases. The simple but effective example crossover included here with formulas is of the passive type. With it you will achieve a much higher quality of crossover than possible using basic online calculators, and there is enough explanation to enable you to take it to the next level. Math has been kept light.

For illustration, I will be assuming a dome tweeter and a mid sized mid/woofer but with a little common sense this tutorial can apply to more than just two-way systems using typical drivers.

• Adding a sub to existing speakers - https://www.diyaudio.com/community/...overs-without-measurement.189847/post-7378329
• Notes on 3-way speakers - https://www.diyaudio.com/community/...overs-without-measurement.189847/post-3031202

INDEX

Preparation
Post 2 - Choosing the crossover frequency - Part 1
Post 3 - Choosing the crossover frequency - Part 2
Post 4 - Directivity
Post 5 - Choosing the level
Post 6 - Baffle step diffraction
Post 7 - The design process

Design
Post 8 - Flattening the woofer's impedance
Post 9 - Flattening the tweeter's impedance
Post 10 - The woofer's crossover
Post 11 - The tweeter's crossover

Tweaking
Post 12 - Phase and diffraction
Post 13 - Tweaking the woofer
Post 14 - Tweaking the tweeter
Post 15 - Tweaking the system


You'll need to achieve these goals…
As this tutorial covers more than you may need, here is a list of the essential steps in case you don't plan on reading all of it.

1. Choose a crossover frequency based on your drivers

2. Choose the tweeter level (how loud it should be)

3. Flatten the impedances

4. Add the crossovers

…then on to tweaking. The rest of this tutorial helps in understanding how it works which will make the tweaking process more successful.

The goal of a crossover
Is to blend the sound from the two drivers (woofer and tweeter) so they work together as one. It may need to make the drivers as loud as each other, to divide the frequencies between them, and to correct or sidestep the limitations each driver will have.

Crossovers will not cut the drivers off suddenly at some frequency. There is a more gradual roll-off, somewhat like rolling a treble or bass control down. This means the drivers will be working together near the crossover frequency.

I began working on this program years ago, back in 2010. Now, having just finished version 3, it occurred to me that sharing it here might be a good idea, since I use it regularly myself. Essentially, it is basic software that can simulate SPL versus frequency. It is straightforward, intuitive, and gives me exactly what I need when working with loudspeakers.

Some of the features:

• A large database is included and is mostly up to date.
• To add a new driver, only six parameters are required: Qms, Qes, fs, Mms, Dd/Sd, and Re. The remaining parameters are calculated.
• Clicking the counter above the listbox displays the full parameter list.
• The Tools section contains several tools, such as TS parameters calculation, Resonance frequency variation, Added resistance to Re / Change in Mms, Air core inductor, and others.
• You can simulate three enclosure types: Closed, Vented, and 4th-order Bandpass.
• The closed box type also includes a Linkwitz Transform tool.
• The txt button in the header shows a list of the main parameters, ready to be copied into a file or onto a website.
• On the Formulas page, you can see relationships between parameters and copy them into Excel.
• The Up/Down arrow keys change values by +/-1. For fine-tuning, hold down the Shift or Ctrl key first.

You can download the program from Softpedia or directly from audioweb.cz, where an updated driver database file is also available.
Some antivirus programs may mistakenly flag it as suspicious - this is a false positive. To verify its safety, you can check its status using the VirusTotal API.

gooday to all,
i buit several elekits succesfull, no problem at all,
this latest preamp preamp 8550 gives me trouble, one channel completely dead, most happening sooner or later hihi,
i dont expext an instant solution, thats not possible,
but maybe someone can se me on the right way to start, components are placed ok , so are tubes, they glowing ok,
im in the process of measuring voltage testpoints, maybe someone is familliar with the testpoint table manual,
under reference dc voltage elekit statet tp7 +2v tp tp8+2v tp17 +2v tp18 +2v , i can not find these points, maybe someone is familliar wth this manual or built the kit.......
regards carlos

Edited to correct Vb to Fb ....

Hi,
I joined up here recently. I have designed several subwoofers and built a couple of 3 way kits but this is my first foray into real design. I am working on (slot) ported bookshelves based around the Dayton RS180P-8 mids and the HiVi RT2C-A planar tweeters. In retrospect I am not sure the HiVi’s were a good idea but committed now.

Working mainly in VituixCad - the boxes are built and for the last few days I have been running impedance and response measurements using REW and a Sonarworks calibrated microphone. Speaker is 1.5m off floor in a large cleared room (3m ceilings). I have merged Near and Far Field files with Diffraction files in VitruixCad and have started to play with crossover design but before going further I need to resolve a number of issues - lets start with this one:

I have a calculated tuning frequency Fb of 44Hz which as expected aligns exactly with the dip between peaks in the measured Impedance curve. As I understand it, the port maximum should also align with Fb however it is at 57Hz. I have measurements for two port lengths and for the ‘calculated’ port I have measurements for empty, lined, filled and lined + filled. The ~13Hz discrepancy between Fb and port maximum is consistent in all cases. This causes a significant bump in the bass response when combined with the cone measurement.

I then thought to check measurements with my UMIK-1 microphone. This was quick and dirty but behold the port frequency is now as expected. Moreover the shape of the curve is now very close to modelling while the measurements with the sonarworks microphone show exaggerated peaks and unexpected inflections.

Any input appreciated - thoughts on what I might be doing wrong or what to check next?


Cone Nearfield response. Blue is UMIK - offset for clarity. Other 3 are Sonarworks mic with various fill.


Port Nearfield - Green is Umik

Uses LSK189 for input.
Buy at mouser.com: https://www2.mouser.com/ProductDetail/Linear-Integrated-Systems/LSK189-TO-92-3L-BK?qs=T%2BzbugeAwjjUrS49wFak%2Bw==
Uses ECX10N20 and ECX10P20 for output.
Buy for example at: https://gb.profusion.uk/uk/audio/transist/lateral-mosfets

The input JFET pair can be other JFET, too.
Bias in output is set to 300mA.
THD is 0.00020% with the LSK189.

Hi everyone,

I’m currently working on a compact audio device and I’m looking to design a dual-rail ±17V power supply. The current demand is fairly low (~500 mA), and the whole build needs to remain low profile and as noise-free as possible for audio use.

The idea is to use a single-rail SMPS as the primary power source, then derive both positive and negative rails from it, whether through DC-DC converters or another topology is still open at this point.

I’ve been following Mark’s contributions on power supply filtering for some time, especially the AmyAlice designs, and I plan to integrate a similar filtering stage at the output. I’ve gone through a number of previous threads and feel fairly confident about that part, but I’d love to hear your ideas or experience when it comes to:

• Choosing an appropriate SMPS module (PCB or chassis mount) for this kind of setup
• Approaches to generating dual rails (±17V) from a single supply input
• Layout or integration tips when combining regulation and filtering for audio-sensitive applications

Would be great to hear what’s worked well for you, or any pitfalls to avoid.

Thanks in advance for any input you’re willing to share!

Best,
Ahmed

Hi guys, i need crosover schematic for this speakers .Have enclosure and drivers but not crossover. Does any have schema for this Accuton c25 6 012 GG and C158-6-851.

Hi,

One of the problems with the titanium based diaphragm compression drivers is the breakup around 11khz-13khz. There are a couple of ways I have been reading it has been dealt with as below:-

a) Use of non titanium materials that inherently dont have breakup in the pass band, these have some sort of plastic like engineered material
b) Titanium based diaphragms with embossed strengthening pattern to increase stiffness and move the breakup above the 20Khz range
c) Use of ring radiator diaphragms, the ring is driven by the mechanical center and ring stays pistonic to a very high frequency, the material thus is less important here I believe

I think such driver when implemented correctly with a good matching waveguide and crossover can take away the harshness of CD and make it sublime like a good dome or even a ribbon.

So, can we have a list of such drivers please?

Here are few I know :-

1) JBL CDs with embossed pattern, probably of titanium.


2) Then F151M-8 1" Ceramic ring radiator from Eminence.

3) JBL D2,revolutionary driver, with two rings facing each other, now patent has expired and so several clones available at Alibaba


4) B&C DE360


Please post here if you come across more.

Thanks and Warm Regards
WonderfulAudio

Hello.

I'm looking for the top midrange drivers for open baffle, to be used approx 400 to 3000 Hz in an active system.
I am now using B&C 8PE21 and considering Radian LM10n plannar. I like AMT tweeters - using Beyma TPL-150H open back now.

The Purifi 6.5" midrange looks appealing too, but haven't seen comments about them for OB.

What are the better OB mids out there, for this range?

Thanks in advance!

Hello fellow diy'ers.

I recently received my ROAR15's from the CNC shop and was in the process of loading them with B&C 15SW115 when I noticed something amiss with one of the drivers, coil scratch, so that driver is going to be returned to the dealer.

The other one worked as intended and despite having only one ROAR15 up and running I still wanted to share some pictures and very early impressions (that may change as I get more time with them and both of them working).


They currently reside in our apartment's living room, so I cannot test them properly (you know, neighbors...) but even so I also do not have the means to properly power them, at least not yet.

Anyway, on with some pictures.

The driver baffle and interface:



Next to above we see one of the quarter wave segment inlets into the resonator:



The post summation quarter wave resonator:



The one that worked:



And finally the state of things as present, I will given time arrange things a little better, what you see blow is a work in haste, perhaps I will be moving them into another room seeing as the person I live with has voiced some opinions on the matter, can't say I blame her, they are actually somewhat noticeable.



Preliminary impressions of one ROAR15, corner loaded, in a relatively small room at low levels, is that it sounds massive, in this placement it also digs very deep, and I do notice a lot of bass details both in the lows and higher up in it's range.

It does seem to have the ability to be both punchy and dig deep at the same time, this trait it was also noticeable in the ROAR12 previously evaluated but this is a more of everything sort of experience in comparison.

This is not much to disclose given the conditions described above but it is a start.

I will be putting some more pictures and impressions up once I have the new driver mounted, until then.

The Iron Pre is now listed in the diyAudio store for anyone to purchase.

Until the 'Build Guide / Build Thread' is created, this post will contain all current schematics and notes for the Iron Pre sold through the diyAudio store. Check back frequently to ensure you have the latest files.

Sep 14 2023 - Below is what you're waiting for! See some awesome information and help from 6L6 on the SE build. A new thread and the guide using the web interface will be posted ... soon. Post #2291

Background

Hello Happy DIYers / Greedy Boyz!

I am thrilled to announce that Zen Mod's Iron Pre essentials kits will be offered in the DIYAudio store. This is not a group buy. You can learn more about the project in the thread linked below.

https://www.diyaudio.com/community/threads/whats-wrong-with-the-kiss-boy.293169/

Highlights include matched Toshiba JFETs from Nelson Pass and high-nickel CineMag transformers. 6L6 has volunteered to post one of his incredible build guides also.

If you're a Smiths fan, you may ask, How Soon Is Now? They should be available for order before the end of the year. At this time, we have enough parts sourced for 100 SE and 50 balanced kits.

The next obvious question is, how much? Costing is not final yet, but the goal is $100 for the SE kits and $125 for the balanced kits; a tremendous bargain. We have contingencies for all the parts, and we hope that this will be a permanent addition to the store. However, for now, we can only promise what we've got. Get 'em while you can.

Click the link below to see what will be included in the kit, answer a few questions about what you might like to see in the future, and get on the list.

Note - The n-channel JFETs will be 2SK370.

Quick and Dirty Startup Process

This happens after: the boards are stuffed, the AC supply is verified and connected properly, and I/O has been connected. Nothing needs to be shorted. Note the additional step for the V4 SMD version.

1. Set V+ and V-
   
   Adjust P1 and P2 for each board until V+ is +15V0 and V- is -15V0
   
   GND, V+ and V- pads are clearly marked on PCBs.
   Do not move forward if you cannot adjust the voltages to within 0V1 or if the voltage seems unstable.
   
   
2. For V4 SMD Only- Set current through JFETs
   • Set DMM to DCmV.
   • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
   • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
3. Null DC offset
   • SE
     • No jumper caps in place for JP1 or JP2
     • Measure at center pin of JP1 and JP2 NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers for your choice of gain.
   • Balanced
     • No jumper caps on JP+ or JP-
     • Measure at pin 1 of JP+ and JP- NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers.​

Updates

4-May 2023

Edited 7-Aug 2023. All in-line photos have been removed. Please see attached files for all documentation.

5-May 2023

Updated Single-Ended BoM to correct 330R part notations in the gain stage to R28 and R29.

Attached are the Bill of Materials / Parts Lists - Note File Names for Balanced and SE

26 - May 2023

Updated SE and Balanced Bill of Materials to indicate that snubber components should not be installed.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v5.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v5.pdf

27 - May 2023

Updated SE and Balanced Bill of Materials to correct and clearly note which diodes should be installed for input switching.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v6.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v6.pdf

1 - June 2023

Note - No changes required. However, the packing lists some of you will receive may note LM336-5.0. That was a typo; apologies. The correct parts (as supplied and noted in the BoM) are LM336-2.5.

Removed the link to sign up indicating interest in kits. Those currently on the list will get first priority for the next round of kits. After that, they will be sold through the normal process through the store.

6 - June 2023

There are two gorgeous prototype chassis available; one designed specifically for SE, and one for Balanced. You can find some details in post #431. The depth for both chassis is 280mm. There is additional information sprinkled throughout the thread re: acceptable sizes and some potential part numbers for IECs, input / outputs etc. along with pictures of some examples. Please search first before asking chassis questions, and I'd recommend using the latest posts' information. Again, they are prototype chassis, and anything could change at any time until the design is finalized. The best source of information re: the chassis is directly from Modushop until they are sold in the diyAudio store. Timing TBD.

8 - June 2023

Added parts placement and pcb layouts for those interested.

30 - June 2023

V7 - Minor Updates to BoMs. QTY added. Ensure to check quantity per board against the quantity you need for your project. Added links to a popular online website to show examples of parts that will work for the connection between the main boards and the twister boards for input selection / LED power etc. Added generic descriptions for those that would prefer to select their own parts.

1 - July 2023

V8 - Minor Updates to BoMs. Added heatsinks for M3 if 12V relays are used.

7 - Aug 2023

I'm excited to say that more kits will be available very soon for 'round 2'. Continue checking this post (as always) and the thread overall for up to the minute updates.

In his graciousness, ZM has made some minor running changes. Changes are:

• Updated transformer snubber circuit.
• Easier positioning / mounting of the CineMag transformers in some situations.
• Changes to allow easier use of some logic circuits for input switching.

Boards that include the changes will note "2023" vs. "2021" on the silkscreen. The Twister board accompanying the 2023 boards notes V.3. Both 2021 and 2023 boards are included with 'round 2'. You cannot choose which you will receive, and you will not know which you will receive until they arrive. Do not fret if you get a kit with 2021 boards. If you need to use a particular type logic solution, there is a very easy modification previously noted in the thread, and the snubber is not necessary. The changes made were a kindness from ZM, but all 2021 boards can be made to function just like 2023 boards with a few user-tweaks described in the thread.

Note - The attachments have been packaged and note which files to choose for the respective boards. Previous attachments and in-line thumbnails / photos have been removed for clarity. The BoMs have been updated slightly for clarity.

9 - Aug 2023

There is a minor error on the silkscreen for the boards marked Iron Pre SE Zen Mod Labs 2023. The polarity notation for C11 visible when the cap is installed is incorrect. Ignore it.



13 - Aug 2023

His Mightiness created two graphics for how to wire standard pots for both SE and Balanced. Attached.

29 - Aug 2023

Minor updates to balanced BoMs. Removed reference to D15.

31 - Aug 2023

Added wiring diagram for AVC for SE. See post #2113 for context.

21 - June 2024

All testing for the Super Mega Deluxe version is complete. Kits will be back in the store 'soon'.

25 - September 2024

"Soon" is relative. 🙂. SMD kits are on sale. The schematics and files for the Super Mega Deluxe (SMD) have been attached in their appropriately named .zip files. Enjoy your builds.

26 - September 2024

A few people purchased the "completion" kits for the V3 and earlier boards and were wondering if they could be used for the V4 SMD kits. A lot of the parts are identical, but below is what you'll need in addition and to swap a few parts.

For balanced you will need:
4x additional 825R or 820R resistors - I like these Vishay BC 825R
8x 58R or 62R resistors - I like these Vishay BC 62R
4x 1R resistors - I like these Vishay BC 1R
8x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
4x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

For SE you will need:
2x additional 825R or 820R resistors - I like these Vishay BC 825R
4x 58R or 62R resistors - I like these Vishay BC 62R
2x 1R resistors - I like these Vishay BC 1R
4x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
2x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

27 - September 2024

Some potentially helpful additional parts in post #3784. If people have more helpful suggestions, I can add them.

3 - February 2025

Added diagrams for setting buffer current in V4 builds.

Hey everyone,

I moved back into my childhood home recently and I'm also getting back into audio after being away from it for a few years. My late father made some built-in cabinets with a fireplace in the living room as seen in the attached photo. Since my old man built them I don't want to alter them too much, but the cabinets and the position of the couch, which really can't go anywhere else, make speaker placement difficult.

As you can see in the photo, there are two large cupboards on both ends of the built-ins. The space inside is about 38" wide, 35" high, and 20" deep. So I've been wondering if I could put some speakers inside those cabinets, rather than on the floor in front like I'm doing now. I have a pair of JBL L166s now that I may experiment with, but I'm wondering if something even bigger might make better use of the space available.

I have a chance to buy some Altec Lansing 604-8k speakers in 620 cabinets at a reasonable price and I'm wondering if they might work. The 620 cabinets are too tall, but they would fit if I remove some trim around the cupboard doors. I'm also a pretty good woodworker and could easily build some smaller cabinets that would slide into the space available. I could replace the doors with custom grills too.

Does this sound like a good idea, or am I crazy for even thinking about it?

Any feedback would be much appreciated.

Thanks,

Andy


A

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A thought occurred to me yesterday when I was wiring up a driver and some speaker terminals.
Most terminal tabs have a hole in them to pass a wire though, is this hole size telling us that this is the largest wire to use when soldering?
The subwoofer tabs have a hole that took 1mm<2 wire and while I know this wire size will take a reasonable load sometimes I think I should be using something that looks more robust and capable of handling more current although I doubt I'll ever put more than a couple of hundred Watts though this old Shiva

I recently purchased a couple of well made boxes thinking that I had suitable drivers in the stash based on the sellers description.
I do but only 2 of them and they are old model Tandy drivers more suitable as midrange not as woofers or subwoofers.
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I'd like to be able to use these well made boxes if affordable drivers are around. Asking here while I search though sites.
Australia so my options are limited

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Hey everyone,


While browsing through some old threads recently, I came across a neat little project from Paul Carmody dating back to 2013—the "Voxel" mini sub. For those unfamiliar, it’s a compact 7-liter subwoofer build using the Tang Band W5-1138SMF, capable of reaching down to about 35Hz (F3) in a surprisingly small footprint.
You can check it out here:
🔗 Voxel Mini Sub Thread




It sparked an idea:
What if we could adapt the Voxel design into a full-range "WAW" (Woofer-Assisted Widebander) system?


I’ve had a pair of SB Acoustics SB65WBAC25-4 full-range drivers collecting dust since they went on sale a few years ago. The thought was to let the Voxel handle the low end, while the SB65 tackles mids and highs on the front baffle.
Here's a link to the SB65's test data:
🔗 SB65 Driver Info




The drivers appear to have fairly compatible sensitivities. I’ve seen recommendations to cross the SB65 around 400Hz, and Tang Band’s spec sheet shows the W5 plays clean up to about 1kHz, so there seems to be a usable overlap.


I’m still fairly new to WAW-style designs and full-range applications, so I’d love to get some input before jumping in. Has anyone tried something similar? Any thoughts on enclosure tweaks, crossover approaches, or potential pitfalls?


Appreciate any insight—always grateful to learn from the experience of this community.


Cheers!

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