It's cold and snowing in Brooklyn, NY, a great opportunity to start a new thread.

I recently built these Telefunken OB speakers inspired by Kevin @ glowinthedarkaudio.com. I think it's extremely kind of him to be sharing his knowledge and experiences. Inshort Kevin helped save me time and money. I just recently started on this diy speaker hobby and new to woodworking, and the reason I choose these OB speakers is that I don't have access to computer programs that are needed to built closed or vented enclosures. I also wanted a challenge in woodworking instead of just using a broad as an OB.

I'm very happy and glad I built these OB's. I built mine to be flexible. The front panels are removable, incase if I want to do 2 or 3 drivers, or even an array of drivers. I also built 12 inch plates for smaller drivers that can be easily swapped. I used half inch plywood, if I built a second pair of these I would go with hardwood.

These OB are very forgiving, just about every speaker I have installed sounded great. Of course certain drivers sound better than others, but just about all of them displayed good imaging and separation between the high and low frequencies. The following are drivers I have used: Fostex FE208sigma, Fe168Esigma, Coral Holey Basket, Elac 8 inch, Akai 10 inch coaxial, Berman 12 inch guitar amp speakers. So far my favorites are the 2 Fostex and Coral's. I absolutely love them with my SS accupahse e202. I also played them on a brand new Decware SE84CKC. Maybe the Decware needs to time to breakin, but it's not sounding as dynamic as the accuphase. Haven't done any A/B speaker tests yet, will report back when I do. I'm curious to see if they sound better or more open then regular speakers, But my first impression is that the bass is not as tight or dynamic as boxed speakers. I'm not a bass junkie anyway, definitely enough bass for me.















Thanks for reading, would appreciate any advice.

Does anyone have a source for the usual practice of designing loudspeaker at 2/3 of the each drivers RMS (W)

thanks!

Let me know. Thanks!

I'm saddened to announce that we've lost a friend of our DIY community. Carlos Mergulhão, an undeniable and inspiring figure in the do-it-yourself and audio amplifier world, passed away yesterday, October 7th, 2023. He consistently encouraged many of us to explore, innovate, and create. While at times controversial, his passion and dedication to our movement were undeniable. His legacy will live on in every project we undertake. Our deepest condolences to all who mourn his loss. May he rest in peace. 🙏🖤

Mouser announced EOL for Elna Silmic II. Anyway they have very lmited stock now..

Initial Goals

I am looking into getting/building a set of relatively small stand speakers to fill a room that is around 25square meters or 270 square feet.
The amplifier for this system is a Marantz 2216B giving around 16W into 8ohms.

I have found locally a pair of Yamaha HS7 monitors sold for parts. The amps are working, but the woofers are torn and the boxes have a few scratches (that I can live with). I am looking into options and deciding how much sense does it make to use these as a basis

The boxes are made out of 20mm MDF, and are 210x332x284mm giving ~12.8L (internal).

The woofer's center is 6.5" and the tweeter's is 1". And they have a port behind the tweeter that is tuned at 50Hz.

The woofer is at around 120mm from the bottom. The tweeter is at around 65mm from the top. Both speakers leave around 10mm from their own edge to the speaker's edge (end of tweeter waveguide and woofer plastic bezel)

Thoughts

1) I guess the simplest would be to get their own woofers (40 bucks a piece). The problem is that the 2216 does not have a pre out, so I would have to use the tape out and control volume through their own controls. Plus, the woofers are not really a well known quantity, and they do need some EQ to fix some issues. Plus, they are 4ohms, so more difficult to drive in case I decide to experiment with them any further.

Here is a link to detailed measurements
https://www.audiosciencereview.com/forum/index.php?threads/yamaha-hs7-review-studio-monitor.19761/

2) Get some other speakers to use with the integrated amps and active crossover. I understand that finding a complete match that sounds well is a long shot. And I would still have the same issue with the pre-out.

3) Get rid of the integrated amps and use some full range speaker in them , leaving the tweeter and some electronics in place to just fill the holes.

This probably makes the more sense. Especially since the monitor electronics are not really built for fidelity. I would still have to at least remove the limiter.

An issue with this would be that to fit a round woofer I would have to modify the tweeter's waveguide.

Using my mediocre experience with speakers, I was thinking perhaps something like the alpair 11MS that seems to work ok with even smaller boxes, or the Fostex FF 165 WK (the bass reflex boxes suggested are quite larger though). The fostex has the extra pro that it would fit without having to modify the tweeter.

Can you please suggest me some drivers that make sense for these boxes? Or maybe just call me an idiot and point me to the correct direction?

Thanks in advance

Hello, i was wondering if i got things right,

assume we have 2 transformers in this configuration:

1x230V Primary
6x8V 5A Secondary

1x230V Primary
2x15V 5A Secondary

what would be the safest route to protect the whole device? i read some people just use a fuse on the primary but that doesnt make much sense... the 8V 5A secondary draws 40W max, so to protect the secondary effectivly i would need a (40/230=0.17) 0,17A primary fuse (?!) please enlighten me here

I'm new to circuit design and trying to read and learn a lot, but almost every calculation for common emitter amp circuit components is slightly different. I understand that there are many variables in this circuit, but all these different methods just giving me more confusion.

What would be the right way to calculate Rc and Rc out of these:


Calculating the Collector Resistor (Rc):

Version 1: Rc = Vcquiescent / Icquiescent = (Vcc / 2) / (Ic / 2). So here we have a maximum collector current (Saturation). We want the quiescent current to be somewhere in the middle, halfway of Ic and use that to calculate Rc. This doesn't make much sense to me as in this case Icquiescent becomes Ic as the resistor will determine the maximum current as Icquiescent.

Version 2: Rc = Vcquiescent / Ic = (Vcc / 2) / Ic. Using maximum collector current. (Saturation)

Calculating the Emitter Resistor (Re):

Version 1: Re = Ve / Icquiescent = (Vcc / 10) / (Ic / 2). Using the quiescent collector current to calculate Re. Ve is chosen to be one tenth of Vcc. We also assume Ie is same as Ic.

Version 2: Re = Ve / Ic = (Vcc / 10) / Ic. In this case we use the maximum collector current available at saturation.

[SOLD]

Up for sale a pair of VT-62 / 801A.

One is Hytron, clearly NOS because it still has an original customs sticker which typically fades quickly after a few hours of use. The other is RCA, looks NOS for what I can tell.

On my calibrated TV7-D/U, Hytron tests 67, and RCA tests 70. Threshold for good is 38.

I would sell them for 130 EUR (or 145 USD), shipping included. Returns accepted as long as they are received in the same electrical and cosmetic condition as they were sent.

Next lot I will be posting is a bunch of Telefunken RS237 and GE VT-4C.

Cheers
Ignacio

[SOLD]

Any experiences with this little circuit?

Just got in a bunch of 4, 5, 8 Octal, 8 Loctal, and 9 Pin Tube Sockets - All American Made

Plug and play. No drivers required. Nice sounding DAC, made with quality components. Nice acrylic top plate so you can see inside. Very cool look.

$125 plus shipping. Would also trade for a MiniDSP 2x4 HD

Thanks!

A few years ago I fully redid the layoutdesign for my elektuur lfa50a.
the componentplacement is about the same but there is more room voor biggercaps and foil c's. I also made a large board for the big powercaps. As you can see on the attachment. So there are almost no wires anymore. I think that looks very cool. And the best thing is its sounds really great too.

I have an 2sk389 as inputdifamp because 2sk146v was not avaliable anymore. And no inputcap. Because my preamp has outputcaps. But I can always put room for one on the layout if you want one.

Let me know, Roy

To me the lfa50a is a great amplifier

$325 plus shipping from Las Vegas NV

Also have a KECES DA-151 USB DAC which I'd sell for $125 plus shipping

Is it possible to change the sensitivity on Realistic apm 200 meter? I find that I have to turn up the volume to get any kind of meter movement. I have this connected to my Bryston 4Bst.
Cheers, Doug

I have a large quantity of the guitar amp specific open frame Push Pull OPT's seen here, still in their original 8 pack boxes from 1990. These are the same transformers seen in my "under 100 WPC" tube amp experiments dating back to the early 2000's. Originally made by Schumaker Electric for ADA Signal Processors for guitar amp duty, they are rated for "80 VA from 82 Hz to 5000 Hz 6600 ohms to 0-4-8-16." They work well at 3300 ohms to 0-2-4-8, which is how I usually run them.

It is pretty hard to make an OPT that only goes to 5KHz, so I have tested them in HiFi applications. They were used in my 300Beast, a zero feedback push pull amp that used 300B tubes. Here they went from 25 Hz to 18.5 KHz at 10 watts with some saturation seen at 28 watts below 30 Hz. They do better when driven with low impedance sweep tubes, and slightly worse in an SPP amp with EL84's that really want an 8000 ohm load. They are a standard size as I have found some end bells from other transformers, that fit.

Stuffing over 100 watts through one for guitar use seems OK, but don't play bass through one beyond about 35 watts. I will sell small quantities to interested builders. for $30 each. They weigh a little over 5 pounds each so shipping isn't cheap and international shipping is probably not viable. Up to 4 transformers will go into a medium flat rate box for delivery in the US for $19

For those that shop hamfests, I have been selling these at the Dayton Hamfest for years, but at a higher price. I will be there again this year, so if you want these at the Hamfest, mention this forum to get them at $30.

Can anyone give me accurate excursion of these bass panels? How far off magnet array is the diaphragm on these. Particularly interested in Maggi

I think these have been mentioned on here before: (Connexelectronic)

https://hifimediy.com/product/smps300re-36v-dual-voltage-110v-power-supply/

I bought a pair of +-36v 300w models to replace the linear psu in my Krell KSA50 clones. (derated to about 30w to drive the mid woofers) so I am hoping this isn't a mistake!

Since I have the pcbs for a proto dac lying in the cabinet, I´m searching these resistors...
Does anybody know a source for them or has these for sale ?
Best regards,
Eddy

Hi! I would like to improve the noise figure of the LM741 equivalent discrete design. What are the key areas that i need to work on?It seems to me that the input differential pair contributes the most in noise. Thanks! I am using 3904 and 3906 transistors.

Hi everyone, does anyone have a part listing for the Hypex SMPS400A180 power supply? It's for the EV Electro Voice ELX118P Sub-Woofer. Please contact me. Thanks in Advance.

Currently I am trying to getting some of my old builds in action again. Back in 1984 I build a pre-amp based on the line amp (and MC) of the original prelude.
btw, I avoided the other overly complicated printboards of this design.



The line amp in a discrete build opamp see attachment. Back then I replaced the input electrolytic capacitors with MKT types and removed the output elco completely. I included a small circuit to adjust offset on the output manually.


While the sound of the unit is fairly good in my ears it has been build with standard none-audio grade parts, inclusive a big electrolytic capacitor in the feed back line. And of course it's a very old design.


Would it be worth it to try to improve the pre-amp? Could I use an auto offset correction as implemented in the crescendo millennium? (if yes how?)
Any ideas which other changes would give me a worthy sound improvement?

I don't mind spending some $$$ but don't want to go over the top (like 2 X 220 uF foil capacitors).

im reparing a technics su-c2000
the preamp produces low volume that is a bit crunchy

2.36V on base of Q10/Q12 on right channel
same problem on left channel.

I have taken some volt measurements. see attached documents .
have printed voltage that I got with the multimeter on the schematic

i think the two diodes are broken MA29WATA they are also called MA2C029WA can i find similar some where ??

Hi guys, I have this Marantz PM66 SE KI Signature that doesn't have a relay click when powered on. I experimented with test speakers and the output sounds fine if I manually push and hold the relay with a plastic stick.

Can anyone please help a beginner out with this one? The relay doesn't appear to be pitted.

Many thanks to anyone with the patience to help!

Hi!
My friend has burnt out his Tannoy DC2000. Who can tell me the drivers' part number of Tannoy DC2000?
In case the stock bass unit is unavailable. Any suggestions about any premium grade aftermarket bass unit that is able to replace the stock bass unit?

I attached the crossover network for the DC2000.

Thanks!

I would like to cut open these old vacuum tubes to use the glass bulb and a few of the parts. Er....I actually already cut one open and became concerned about the dangerous elements that may be used in these tubes. Questions: 1) is it just to dangerous to open these and use the parts? 2) Is there a safe way to minimize the exposure to the dangerous elements used in them?

Hello, I plan on using SigmaStudio with an ADAU1701, such as the DSPs available from Parts Express, Wondom (Sure Electronics), or TinySine. My audio flow is 2 in, 4 out with some slight differences from most 2x4 projects. My hope is to determine if this planned setup will work conceptually before ordering any hardware. Once confirmed, I’ll do a much deeper self-study of SigmaStudio. See attached audio workflow.

1. Is this audio flow possible with SigmaStudio via an ADAU1701?
2. Does the order of the audio flow follow best practices? E.g., it is not clear to me where to best adjust volumes/tone levels.
3. If the DSP is limited with GPIO analog inputs for the potentiometer volume/level controls, can they (e.g., bass & sub-bass levels) be adjusted at/before the amplifiers with potentiometers?
4. If GPIO analog inputs are limited, I don’t have to have the midrange control. The purpose of the Analog & Bluetooth volumes is to adjust the volumes of these two inputs relative to each other. To save a GPIO analog input pin, can I instead use a potentiometer balance control to adjust these two input volumes relative to each other?
5. Can the ADAU1701 combine both audio inputs (analog w/AptX HD) as planned?
6. Some SigmaStudio projects have a DC block filter at the input. What is the purpose/benefit of this? Should I add it to my audio flow?
7. Am I missing any elements?

BTW, some of the Dayton, Wondom (Sure Electronics), and TinySine amplifier boards also come with DSPs. I believe it is possible to stream Bluetooth audio to a slave (e.g., from primary DSP to amplifier DSP), but I am worried about BT connection reliability. My preference is to have a physical connection between the DSP and amplifiers or use an amplifier with a DSP for sub-bass and physically connect to the other two amplifier. I’m not sure if the latter is possible, but it would be preferable to use a DSP/amplifier and send digital audio to the two other amplifiers. Essentially, I would only need to purchase 3 boards (3 amplifiers - on w/DSP vs. one DSP board and 3 amplifiers). Is this possible?

Thank-you for providing feedback.

Greetings all, I have assembled the Flagship Dac from Gabsters YouTube video's Ropieee and Roon installed. Everything powers up. The 5" screen functions. I am unable to stream in my location as there is no internet available. I am feeding it from an Apple Mac mini digital out. I have tried USB, HDMI and Ethernet but get no signal output. The monitor Pi displays the word MUTE I cannot find a way to unmute it. I feel I am missing something obvious like missing software or a patch cable. Any thoughts? Thanks in advance!

Looking Schematics or Service Info for RCA RT-21 pro Reel to Reel machines. But the 21A and 21B variants. if anyone has any info, parts, schematics, etc etc.please let me know

Started my DIY research by looking into Troels, but to be honest, I'd rather put more money into the drivers than capacitors. Also, Troels' designs don't measure off-axis, and I happen to be in a suboptimal position quite often. I really like Monkey Coffins and towers since they look dope as hell and double as a shelf for my wallet and keys. I like the idea of the Open Source Monkey Coffin, but it's too damn expensive for me. Max I'd go for is 2k Euro for the pair. Troels' designs that tickled my fancy are Seas 3WC MkII, Faital 3WC-10, and Ekta MkII.

Here are some notes:
Possibly under 2k Euro for the pair
I'd prefer if they were neutral and flat
Prefer EU drivers since I am from EU
Towers or coffins
My living room is 4m by 6m

Already looked into Heissmann Acoustics, Speaker Design Works and OSMC, but still wondering what else is out there

I bought this to experiment with and it is a VERY impressive sounding DAC with a very simple USB input and rca outputs. This is great for a desktop setup or if you use your computer as a streamer through USB. I recently acquired another Dac with more features to fit my system so no longer need it.

Upgraded Sparkos Opamps or TL071
ESS9018 Dac Chip
DSD Playback
Up to 384KHz Sample Rate

I also have the original manual, original box, and will include a Power Cable.

Asking $300 shipped anywhere in the continental US or $250 with basic TL071 opamps instead of the Sparkos.

Curious if this https://www.mouser.com/ProductDetail/546-274BX is still the ideal choice for a power transformer for the SSE.
It's recommended by George on the SSE website, but I wanted to make sure if it's still ideal.

I have a just bought a pair of Mission 782, which are decent Made in England 3 way speakers from the 90s, with a famous fatal flaw. The Audax made Keraform mid drivers all suffered corrosion on the coils from the glue they used reacting with the solder. It is terminal, and these ones are no exception with 2x dead mids.

I have ordered 2x Audax HM130Z12, which I have been advised are excellent replacements of much higher quality, although I am told they will require a bit of routing to make fit, which is no problem for me.

My question here is whether they genuinely are drop in replacements electrically, as the sensitivity seems to be lower than the earlier Audax HM130Z0 that Mission themselves used to replace the failing Keraforms.

The original (Mission branded) Audax Keraform 82-LF130/QS had a sensitivity I've yet to unearth. I can't find a datasheet online, and all surviving units seem to have failed due to coil corrosion.

The Audax Aerogel HM130Z0 that Mission used to replace these dead units has a sensitivity of 92dB

The Audax Aerogel HM130Z12 that I've ordered (as some say they are an improved version) has a sensitivity of 87.8dB

I'm guessing I may end up with a more laid back midrange than is optimal. Is that likely? Would I then need to attenuate the tweeter and bass drivers to flatten the response? What's the best way of assessing this?

Many thanks
Lucas

I bought this on Reverb a couple weeks ago and a week later my brother and I made a trade and I acquired a Mytek Brooklyn Dac+ and the Mytek has more features and fits my system needs.

I have tested everything on it and it all works great.

• USB Amanero Module
• AK4493
• XLR outputs
• I THINK it is Mahogany with Wenge sides
• Dovetail joints
• Opa1656 Opamps x3
• Black Glass Color
• 12V wall wart
• No original box

If you bought it from Geshelli now you are looking at a $385 before tax. I am asking $350 and I’ll ship for free in the continental US.

my wood-chopping buddy is looking for something interesting and "new" to build. I looked at at 2/3 scale Klipsch Belle with vented back chamber as a noisemaker. 2pi sim looks decent - the port is carrying a loot of the low end as the horn rolls off below 200Hz.

(FWIW I have a 0.83x belle with 12pe32 and think it has a pretty clear sound)

The other classic cabinet would be a 10" version of Cerwin's AB36 - that has a decent 1/4 wave path length- but might choke and get rough above 500 ?

Would the 10" Belle sound decent? Would the CV scaled make it to 500 or better?

My ML431 is out of order. It turns on but seems the protection circuit is on therefore it is not producing any sound at all. Is there anywhere that I can download/buy/find the schematics or service manual for Mark Levinson 431?

I built this to play around with some Mofo amps and my F4s but no longer need it. My friend used it for a few months on his Aleph J and loved it so much he’s getting one built.

I was going to strip it for parts but want to see if anyone is interested in it.

2 balanced inputs (I confirmed single ended inputs work with an adapter)
2 Single ended outputs
VRDN PSU running +-18V rails
All Input and output caps are Wima 4.7uf (because I had them on hand)
Alps RK27 4 gang 50k pot
Modushop Galaxy 2u chassis
Gain switches to switch from 10 DB gain to 20 db gain

Asking $350 and I’ll ship free anywhere in the continental US.

Just received the ACF 12VAC tube buffer board and part kit from Glassware Audio.

I would really like to use 6CG7's but find myself in over my head as far as making sure I'm using the correct cap and resistor values.

Would greatly appreciate any help with determining recommended values for C1-C3 and R1-R13 for that tube...similar to how they are listed for 6DJ8/12AU7/12BH7/ECC99 in the user guide.

Included photos of the part of the guide that I’m working with.

Thanks a ton for the assistance.

Hello, I've read a lot about sandwich structures and some renowned companies have used them.

I'm currently working on a project of mine to make sandwich cones for my speakers.

The materials are:
Faces: Kevlar carbon fiber hybrid
Core: Low density expanded polystyrene (LDEP)

I want to know if there is another sandwich structure or better material than those I mentioned.

Currently I think the best sandwich structure for speaker cone.

After 18 years challenging myself, learning from you and sharing nice projects I will leave this forum.
Also because being bullied and get physical threads without support of the moderators for the last 18 years.
See you all on the next forum.

R.I.P by mod.

Hello fellow DIYers and audio enthusiasts,




For comparison the two graphs look like this:



While not really what I wanted to see, it seemed like the new driver would do the job I was hoping for. Eventually, I decided to build this MKII version of the same Swans speaker kit with the new mid-woofer from HiVi. As for the tweeter, I have opted for HiVi Q3. This tweeter has relatively low resonant frequency and its frequency response is nice. Besides, it matches the visual aesthetic of D6.8MKII and it fits perfectly well within the recessed space which is originally meant for Q1R:



THE CABINETS


A couple more pictures for perspective:





THE CROSSOVER


Since the value of R2 and R3 are a bit unusual, I’ve put 8.2 and 22 Ohms resistors instead - don’t think that there’s a big difference.

Below are the snapshots from XSim with normal and inverted tweeter polarity:





SYSTEM MEASUREMENTS

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Enjoy

This is a terrific network player with excellent sound quality.
It is the Pro Version without external clock inputs. It is an FPGA based player and has the last firmware update installed (v 2.9.17) but this is now a few years old.
Bought this new direct from China quite a few years ago and used it extensively until upgrading to an alternative DIY player a couple of years ago. Physical condition I would describe as excellent and it is in full working order.
Comes complete with the original remote control, but is best controlled by a UPNp DLNA player such as Bubble UPNp.
I replaced the PSU electrolytic capacitors with quality Wurth brand about 4 years ago, so should be good for quite a while (see internal photo).
Can play music from NAS (10/100Mbps), USB stick up to 128Gb, or SD Card up to 128Gb (best in my opinion), in FLAC, WAV, CUE, APE (48khz), MP3.
Please Note - It does not play DSD natively. Upgraded FPGA firmware was promised to enable this but has not materialised.
Outputs as follows;
RCA coaxial: 0.5V p-p, 24bit 192 KHz
BNC (75 ohm) coaxial: 0.5V p-p, 24bit, 192 KHz
AES (110 ohm) coaxial: 5V 24bits, 192KHz
Optical fiber: 24bit, 96 KHz
It is 220/230v operation only, the mains selector switch on the rear is not connected, this is how it was supplied.
I have the original box for transport.
UK based, price is 200GBP
Also on eBay https://www.ebay.co.uk/itm/116117804532

Hello. I installed a limiter 5w/ 100 ohm square ceramic resistor with purpose lo limit surge curent in 100uF cap. The power rating was way to low lo resist at startup and the resistor failed instantly like a fuse. I did 3 attempts with the same results because was wondering why those ceramics broked up
in the same way. I meant at the end of the terminal , and not in the middle as should I expect. All of it was broked the same at the first end whilst resistance of the undamaged part shows close to its nominal value of 100 ohm. My question is why was blowed at the end and not in the middle please ?
I put a picture with one of the resistor out of its ceramic shell.

Hello everyone!

I am looking for input from more experienced DIYers with this project! Any help is greatly appreciated!

Idea is to have two relays: K1 in series with ICL and K2 to bypass ICL and K1.

Powering ON and powering OFF are two separate sequences.

Power ON:
Upon the user operating push button, relay K1 is activated.
After 0.3 seconds (adjustable) relay K2-bypass is activated.
After 1 second, relay K1 is turned off to save on power since now the current is going through K2 only.

Power OFF:
Upon the user operating push button relay K1 is activated.
After 0.3 seconds K2-bypass is disengaged thus directing the current through an ICL.
After 0.7 seconds K1 is disengaged thus completely powering off the device.

I was thinking to create something based only on transistors.
But IC solution will be good too, something with 74hc74 ect.

Hey guys

Just want to check if you guys know how to convert operating voltage of dCS 954 and 974. I see there is a red switch underneath 954 so I guess all I need to do is flipping that without even change fuses, but 974 doesnt seem to have such a switch at the bottom. Any ideas?

I would be interested to hear thought on this project.
My hope is to reduce transmission to my neighbors
Raising the baffle to approx 3ft off the floor should allow for increased cancellation towards my down stairs neighbors.

Still wondering
1 will the whole thing start rocking back a forth once the cone starts moving
2 will vibration to floor joist transmit more or less compared to a frame with rubber feet

All in working condition and not fake. I'm binning the receiver and don't want to throw them away.

I am putting together an Ian Canada diy streamer with a PurePi. I need to source the 3.2V 18650 LifePO4 batteries since I cannot get them delivered to Japan. I see some online that I can order at aliexpress Japan. https://ja.aliexpress.com/w/wholesale-3.2V-18650-LifePO4.html?spm=a2g0o.home.search.0

They are rated at 1500 mAh. I have seen other batteries listed at 1100 mAh, 1800 etc Does this make any difference? Is one a better choice than the other? Thanks for the help.

I recently built a prototype power amplifier, primarily to learn about designing amplifiers. (So it's not really meant to be a "good" amp, but it IS supposed to give me practice, and to be something realistic to measure and tweak, and from which to extrapolate to build a better amp next time.)

Another goal was to minimise cost, primarily by using up components I already had. (For instance, the LSK489 JFETs in the input stages were left over from an active oscilloscope project https://codeberg.org/gtw/active-probe and the IRF510 output MOSFETs were from an RF power amplifier https://codeberg.org/gtw/hfv-1 and I had a 24 VCT transformer from an unused power supply and I already have 2N3904/6s bought by 100s. So I didn't buy much except the IRF9510s.) The other main requirement was to refrain from more power than I need: I have sensitive speakers in a small room, so 5 W per channel gets me over 100 dB SPL peak. Let's call that about 80 dB average for classical music and 90 dB average for rock. That's already above the threshold where my signal-to-noise ratio plummets because my wife screams complaints about my music from the next room: more power doesn't help.

So... in the end I suspect the result is rather idiosyncratic, but it does work, and has certainly been instructive. Now to decide what to do next time...

The schematic:


SPICE analysis before building it:


Evidence seized from the crime scene:


Evaluating the damage:

Hello all,

Most that know guitar amps know that the JC-120 is THE BEST CLEAN AMP EVER - and the best Solid State Guitar amp in existence. These amps are found in all types of music - Jazz, rock and roll, metal, etc (Police - Andy Sommers, Metalica, etc)

Anyway, I downloaded the schematic (the version with 2SK117 not the later opamp version) and had a PCB fabbed with the help of a fellow DIYAudio member (Thanks Craigtone!!)

So the preamp has all the goodies including a quad of 2SK170 instead of the 2SK-117 (a deluxe version?) and behind it is a LM3886 - standard fab of Brian Bell's gainclone amp. Preamp has volume, bass, mids, treble and a Hi Treble switch. With LM3886. it's roughly 45 wpc. No reverb, chorus, etc, just the preamp / amp section. The rest you can do with pedals.

After building the amp/preamp, I bought a real Roland JC-120 Guitar amp, and surprisingly sounds very close. Bandmates were impressed!

Selling as I built another in a nicer case and it has a 200 watt/channel ICEPower 200ASC behind the JC-120 preamp.

Amp $150 + ship

Also have a few PCBs if anyone wants one - free you pay ship and you make a donation to DIYAudio site would be great.

Pics on the way...

Hello everyone,

Looking for pair of these bad boys, anyone can help me??

I have a Hafler Pro 2400 and am the original owner since the 80's! It's been in storage for the last several years and I've recently decided to put it back in use. It does work but I'm wondering if there are any mods or upgrades I should be looking at doing. Also, for the cost of the upgrades, is it worth putting the money into it?
I just picked up an AVA Transcedence 8 preamp yesterday which is in somewhat rough condition. It was missing both tubes and had two holes cut in the top above where the tubes go. My best guess is the the PO upgraded to the 6CG7 tubes which are taller so they cut holes in the top to accommodate them. I'm curious to see if it works once I replace the tubes.

Hi,

I would like to measure the noise of a power supply, like LT3045 based, Salas UltrBiB etc. My oscilloscope (RIGOL 1054z) is not suitable for that kind of measurement, but I've found something.

Noise Measurement Amplifier

Is it ok for that kind of measurements?

Hello everything is fine?

I'm looking for suggestions for ADC components to develop a 3-way studio monitor project, it's a new experience that I want to dive into in a DEDICATED system. I look for ADCs that stand out in specific frequency ranges, aiming to guarantee the best sound quality in each range.

1. For BASS, I need a carefully selected component that is capable of reproducing deep, velvety and smooth bass, providing an immersive and immersive sound experience.

2. For the MIDDLE, I am looking for a high-resolution ADC that guarantees clarity and precision in the medium frequencies, allowing a faithful and detailed reproduction of the instruments and vocals present in this frequency range.

3. For TREBLE, I need a high-speed component that delivers bright, crystal clear treble, adding life and clarity to the higher frequency ranges, providing vibrant and dynamic sound reproduction.

Thank you in advance for any recommendations for ADC components that stand out in each frequency range and that can be used in a dedicated manner to guarantee the best possible sound quality in 3-way studio monitors.

(An update of this OP is available as post #99)

Hello everyone,

I’d like to share with you my latest project, namely building a pair of speakers from a commercial kit - Swans DIY 2.2A and the modification that I’ve come up with. As the name suggests it’s one of the two official kits from Swans and you can find more details about them here: swans diy speaker kits. As Swans Speakers appears to be a division of HiVi Research you can find the same kit under the name HiVi DIY 2.2A instead. Sometimes the cabinets and the components (including the drivers) are sold separately and not as a complete kit (depending on the vendor).

Being a commercial kit, these speakers are not very well documented in terms of technical data and design. That’s understandable - building speakers from a kit is supposed to be a straightforward process where we don’t really need a technical drawing of the cabinets and the schematic for the crossover network. This is the very nature of any kit after all. That being said, on the website above you can find a product manual with instructions on how to build the speakers and some graphs like frequency response and impedance, which appear to be from measurements.

The kit is basically a two-way system employing the following drivers: HiVi D6.8-IIB mid-woofer and HiVi Q1R tweeter. While the latter is easily recognisable as it’s part of the official range of HiVi drivers, the former is a bit of a mystery because there isn’t any official information, let alone T/S parameters, that can be found. It seems that it is some kind of variation of D6.8B which looks identical, but apart from that it’s not very clear. There are some speculations on various audio forums that D6.8-IIB drivers are basically D6.8B not meeting the quality requirements of the manufacturer and they are getting rid of them trough the DIY market as part of a kit.

Anyhow, I’ve decided to share my two cents and hopefully spark a discussion as I find these speakers holding a great potential, but only if you don’t use the crossover that comes with the kit. Despite the many positive reviews I’ve read, there are some people who were not happy with their purchase. In particular, they find the treble too “hot” or “bright” and I have to admit that they have a point. Others think that the bass is weak and I was not impressed either. The issue with the treble from the negative reviews is confirmed by my measurements. The problem is that the frequency response is tilted towards the upper end with a steady increase in the amplitude from around 9-10 kHz to 15 kHz where it gets even worse with a huge hump in the area above 15 kHz. As for the poor bass, part of the reason could be the resistance of the 1.5 mH coil in the low pass filter which is 1.1 ohms! In my opinion, this is unacceptable in a good crossover design, especially when we are dealing with not very sensitive drivers.

In the end I developed a crossover network based on a already existing design involving the same tweeter (Q1R) and D6.8B in almost the same enclosure (slightly different volume/dimensions, but the same baffle width). In addition to that I’ve included an impedance compensation network to cope with the tweeter’s overly enthusiastic response in the top end. As a final touch, I included a LCR network, which is operating as a notch filter aiming at the resonant frequency of the tweeter.

You can find the details of this project in the file below. Hopefully, other people can contribute to the discussion and share their experience with this speaker kit. I would love to hear whether you find the modification as something that is worth it or not. Maybe someone can suggest another crossover solution. Mine is not spectacular and it’s definitely not a benchmark for a good crossover design, I’m aware of that. Not to mention that there is a slight phase shift as well, but I don’t believe it’s audible. On the other hand, there was the same phase shift with the original crossover, so it’s not like I made it worse with my modification. On the contrary, I definitely think that the sound is better now with the suggested crossover upgrade.

- @llex

I have got a HK audio lucas nano 300 in for repair. The issue was the unit not powering up, no indicator lights. Opening up the unit I found that something was shorting out +15V and -15V power rails. The culprit was 2 tantalum capacitors on the preamp board. There were actually 4 capacitors and it seems to be that 2 capacitors are in parallel with the 15V and -15V rail.
After removing the two shorted out capacitors I powered on the unit. This time the unit sprung to life but the amp is on mute mode. The indicator light is red and the LED on the main board labeled 'mute' is also lit. I measured the power rails and everything was ok and stable.
During troubleshooting one of the remaining tantalum capacitor on the preamp board shorted. So I have replaced all the capacitors now, there are no shorts now but the amp remains in mute mode. I tried playing back audio thinking that amp was in idle mode or something. No change, no sound but I heard very faint audio from the small satellite speakers.
I couldn't find any service manuals online, which makes the troubleshooting that much harder. I emailed the manufacturer but they are not willing to hand out the service notes unless its their authorized re-sellers, even for their legacy products. Any help on getting the service manual would be really appreciated.
The amplifier chip is LM4780. Nothing seemed to be shorted there. One thing I would remark is that the -VEE pin is tied to ground. I thought it would be connected to the -15V.
I traced the mute pin track to a SOT26 package transistor, the markings on it is '1Ft'. I couldn't find the pinout, knowing this would also help to figure out why the amplifier chip is mute.
Any help on this would be really appreciated.
Thanks in advance.

Being an electral hobbiest, I love to learn, but unfortunately I'm well out my depth here and as such going to ask for some help!
A local charity has asked me to fix a amped speaker for them - free of course. A DB technologies Opera 402D.
They used it at fundraises and such like.
Normally I'd spend the time to get there myself but that's not really an option.
Whats happening with it is there is a high range and low range speaker. Upon input the low range made no sound and the high range would only make sounds really high and squeaky- paonfully so if the volume is turned up - and though the mid and low were no existent and the high was really garbled. Upon the back of the transformer there is a 4 bit connecter, two leads to each speaker. When there lead are swapped over the symptoms are also reversed. The high range is silent and the low range make the same sounds. Changing any settings, ranges, Mike, speaker inputs etc make no difference what so ever. Nor can I see and damage, blown caps, heating or wierd smells when studying the circuitry.
Would anybody help me with this?
Better still I live in the UK in Aylesbury, if there is anyone even remotely close by?
Appreciate this may be a little forward but If it was not for who it's for I would on not asked, except for advise here and there.
Quite happy to pass on my contact details If that's ok.
Thanks people!

Looking at two ebay candidates. All I need is something reasonable efficiency wise for a <50W amp, that'll work in a U frame style mostly Open Back guitar amp cabinet. The Q parameters and FR are quite different and I'm unsure - except that typically the higher Q is chosen for an OB - of which one to pick. Opinions welcome!

Unit A
Nominal impedance Z: 8Ohm
Power：40-80W
Frequency response：50-17khz
Fs: 59.4 Hz
Sd: 54.325 cm³
Qms: 15.161
Qes: 1.116
Qts: 1.040
Magnet：Y35（Ferrite）
Mean Sound Pressure Level: 95.2dB （2.83V/1m)

Unit B
Rated Impedance: 8 ohms
Operating Bandwidth: 38Hz ~ 2.5KHz
Power Handling Capacity: 175W RMS
Sensitivity (1W/M): 97 dB
Voice Coil Diameter: 2.5 inch
Magnet: 50 Oz
Resonance Frequency Fs: 38 Hz
DC Resistance Re: 7.2 ohm
Qms: 2.8
Qes: 0.385
Qts: 0.34
Equivalent Cas air load Vas: 108.0 liters
Coil Inductance Le: 0.923 mH
Efficiency Bandwidth Product EBP 98.70
Voice Coil Over Hang X-max 3.75mm

Currently enamoured with Joe Tritschler's Tpad phono stage , described in his article , I thought it would be interesting to try the idea with subminiature dual triode 7963 having roughly the same transconductance and gain as the original 5842 when both sections are paralleled.

My question here is about the output stage bias that due to grid current is running with allowable current but very slight positive bias. The original design with 5842 has a grid voltage of .002vdc for a current of about 2nV. The 7963 equivalent runs at 1.7vdc and 1.7uA. Quite a difference , putting that section on the A2 side of things.
Incidentally , I did build two channels of this circuit and measurements are pretty much identical .

My question here is really , how to pull it back to the Vgk≈-1.2V area of operation as the first stage is. I can't lower the grid resistor by much as the impedance of the circuit feeding it is pretty high. Would you simply increase Rk (which starts to ask for bypass cap) or perhaps a 1.8 - 1.9 V drop Led ?
Your thoughts would be appreciated.
Thanks

Hi,
i have a sony vfet 5550 an i don t want to make something wrong to damage the vfets..... they are still good !

1. Does any one knows the Voltages which drops on the Resistor r511/ r611 ( on the Gate from Vfets ) whithout the Vfets .
2. - and the Voltage on the Source will be 0.1 V . I m right?
3. After all measurements if all it is ok it
to protect the vfets... on the +/ - rail better with resistors or Lamp ? , if lamp which power or Ohm must have .. if resistor better Fusible i think? ...which value and Wattage
4.- the measurements without the Vfets must to be from the output ( - ) or from the Big caps Ground?


Thanks a lot!

Hello,I'm happy to spend my time doing my own speakers even if the result is unlikely to be very good.
For my age and my skill it must remain simple,verry simple.
I did after a public project with TBW8-1808 two TL enclonsure (VTP) using BG20 .
I like the gain obtained for the bass, the pleasant sound and the simplicity of the construction (without the complication of filters).
Now I ordered SB20FRPC30-8 and I want to repeat this project for another destination.
It can be the same but it can't be that easy ,to use any driver and expect good results.

Here your help can be welcome if it is possible.
That's only if you can tell me simply
" try to change these dimensions" "or tune the speaker by doing this"

It's a bit late to start studying acoustics, it only matters what I can get now .
Thank you.

Hey folks.

Been searching far and wide for some sort of universal PCB to be able to experiment with different valve pre/power-amp configurations. I was considering making my own, but then I chanced upon the Valve Wizard PCBs. Sadly, though, it seems they're out of print -- And barring them, there really doesn't seem to be any other options that are quite as thoughtfully laid out.

Anyone know if he ever released the schematics for these, or if he sells them through some other vendor? Alternatively, if he doesn't intend to make any more and it might be ok if one reverse engineers them with the help of someone who has 'em?

Otherwise, I suppose I'll simply have to make my own layout.

Hi.
selling this DIY cabinet + drivers. The ATC on the pictures is not for sale. A new front panel will be needed to accomodate the IIT midrange. I had the speakers set up with the ITT, then had the opportunity to purchase the ATC mid, redone (not very nicely) the front panel for the ATC. Now building a new bigger DIY with the ATC mids, so I don't need this DIY anymore.

Maybe an easy project for first DIY with great result.

The sound was superb. The woofer Dayton RS serie is excellent for the price (goes low!). The ITT mid is a gem. A smaller clone of the ATC with double suspension. The tweeter is also very nice for the price. A nice package.

I have the boxes of the woofers and tweeters.

No crossover. 6 Banana plugs per speaker for external crossover. Cabinet is well built with internal damping.

Pick up in Berkeley, CA. No shipping. Would not make sense.

$400 for the pair

where can i buy ds26 crossover software?

Hello.
I'm the owner of a HiVi D8.8 and I'm thinking about putting them to good use.



I have two v ariants in my head so far

• make a Tarkus clone
• 3 band using SICA 5.5 C 1.5 P coaxial (inspired by Adterion, Driva, Minerva, Monoculus, SBS.1 …) and stick to + / - manufacturer recommended volume.

A Tarkus clone
I came across the Tarkus project on Paul Carmody's website
https://sites.google.com/site/undefinition/floorstanding-speakers/tarkus
and its variant with HiVi. Thanks to the help of friends, I discovered that the project in question was called The Apaches, but photos etc are no longer available even from its builder.
Does anyone have any further information on this version of the project? I'm mainly interested in the crossover diagram. From the photos, you can only see the change in the shape of the baffle in the bass section, the use of HiVi D8.8+, HiVi D6.8 and ring radiator tweeter Peerless.

This is what the result might look like



The dimensions of the body are based on the original Tarkus, taking into account The Apaches.
From measured data and after simulation in WinISD - net volume 45l / 32 Hz / -3dB – 28 Hz.
The volume for the D6.8b is 15L (without deducting crossover speakers, etc.) and could be reduced to 9L or less with a vertical bulkhead.
HiVi Q1R is currently listed for treble (but instead of HiVi Q1R, I would prefer to use SB Acoustic SB26STAC).
I would like to divide the switch into two parts (location – red line in the corpus).

SICA coaxial
The second direction in which my thoughts go when using the HiVi D8.8 is its combination with a coaxial speaker. The advantages and disadvantages of coaxials are sufficiently described elsewhere, there is no point in rewriting them or discussing them endlessly. Coaxial is simply one option.

The SICA 5.5 C 1.5 CP coaxial speaker is available in Europe.



Datasheet:

https://sica.it/prodotto/5-5-c-15-cp/

The diBirama website published these measurements:

https://www.dibirama.altervista.org...5c1-5cp-8-coassiale-5-5-1-8-ohm-240-wmax.html

DIY constructions are available (not entirely obvious) and the speaker (definitely modified) is used in commercial loudspeakers.
DIY - Milan, Focus (center), Fiancino, Fianco. Cinque, Cubus Maximus.
Audiophile - SigbergAudio – SBS.1 and Manta.
I'm new here and I don't know the rules in detail. That's why I prefer to give only the names of the speakers without links and photos.

A picture is over 1000 words. The result could look like this:



Dimensions: 310 x 545 x 390 mm. The section through the loudspeaker is without drawn reinforcements for better clarity.
From measured data and after simulation in WinISD HiViVi D8.8 - net volume 35l / 34 Hz / -3dB – 30 Hz.
SICA – 3.2 l (max 7.25 l).

Is there a fatal problem in this solution, in the combination of SICA - HiVi?

The designs correspond to the measured parameters of the speakers and the simulation in WinISD. In the datasheet, the manufacturer recommends a volume of 30 l and tuning at 35 Hz



Red – 45 l
Green – 35 l

Here is a comparison of measurements of both M1 and M2 speakers with available datasheets:



And here is the Impedance frequency response:




For those interested, I would include Impedance frequency response files in txt or zma format. But I do not know how.

Nothing is decided.
Therefore, I am asking for your comments on what was written and tips for DIY construction with HiVi D8.8.
Thanks in advance for the advice and help.

I'm from Europe. Therefore, please, if you have shopping tips, only from the EU.
I have no reason to pay customs duties and taxes for imports from third countries.

Hello all,

I just opened up my Carver PM 300 power amp when there was no sign of the push internal mono switch. There is a clipping switch next to where this should be but an empty socket as shown in the attached photo.

Any input including where I might purchase this switch would be appreciated.

Thanks

Question: Can you list some thermionic tubes used in audio amplification?

The reply:

chatGPT said:

Here are some common types of vacuum tubes used in audio amplification:

1. 12AX7 (ECC83): This is one of the most popular dual-triode vacuum tubes used in preamplifier stages of audio equipment, including guitar amplifiers and hi-fi systems. It provides high gain and is known for its warm, smooth tone.

2. EL34 (6CA7): The EL34 is a power pentode tube widely used in guitar amplifiers and hi-fi systems. It delivers a rich, dynamic sound with good headroom and distortion characteristics.

3. 6L6: Another power pentode tube commonly used in guitar amplifiers and hi-fi systems. It offers a balanced sound with tight bass response and clear highs.

4. KT88: This power beam tetrode tube is known for its high power output and robust construction. It is often used in high-power guitar amplifiers and audiophile amplifiers.

5. KT66: Similar to the KT88, the KT66 is a power beam tetrode tube with a warmer, more vintage sound. It is favored by many guitar amplifier enthusiasts for its smooth distortion characteristics.

6. KT77: A variation of the EL34 tube, the KT77 offers similar characteristics but with higher headroom and power output. It is used in both guitar amplifiers and hi-fi systems.

7. KT120: This power beam tetrode tube offers even higher power output than the KT88 and is suitable for demanding audio applications, including high-power guitar amplifiers and audiophile systems.

8. KT150: A newer and more powerful version of the KT120, the KT150 provides even higher power output and improved performance characteristics for high-end audio applications.

These are just a few examples of vacuum tubes commonly used in audio amplification. There are many other types and variations available, each with its own unique sonic characteristics and applications.

Click to expand...

Question: Can you list manufacturers who still make thermionic tubes?

chatGPT said:

Yes, there are several manufacturers around the world that still produce vacuum tubes for various applications. Some of these manufacturers include:

1. JJ Electronic: Based in Slovakia, JJ Electronic produces a wide range of vacuum tubes for guitar amplifiers, audio equipment, and industrial applications.

2. Electro-Harmonix: This New York-based company is known for manufacturing vacuum tubes for guitar amplifiers and audio equipment. They offer a variety of tubes, including preamp tubes, power tubes, and rectifier tubes.

3. Tung-Sol: Tung-Sol is another prominent manufacturer of vacuum tubes for guitar amplifiers, audio equipment, and other applications. They produce tubes with both vintage and modern designs.

4. Mullard: Mullard is a historic brand known for its high-quality vacuum tubes, particularly in the audio and radio industries. The brand is now owned by New Sensor Corporation, which also owns Electro-Harmonix.

5. Sovtek: Sovtek is a Russian manufacturer known for producing vacuum tubes for guitar amplifiers and audio equipment. They offer a range of tubes with different tonal characteristics.

6. Shuguang: Shuguang is a Chinese manufacturer that produces vacuum tubes for various applications, including guitar amplifiers, audio equipment, and industrial uses. They offer a wide range of tube types and specifications.

These are just a few examples of manufacturers that produce vacuum tubes. While the number of manufacturers has decreased over the years, there is still a dedicated market for vacuum tubes in certain industries and among enthusiasts who appreciate their unique characteristics and sound.

Click to expand...

Anyone on this forum going to AXPONA 2024?

Well I thought I'd show some progress on one of my amps in Progres. In about 2019 I had contacted Phil Marchand for a PM224 kit. Phil told me he really didn't sell diy amp modules kits any more but I implored him, and he relented, putting together a

PM224 R1218

kit for me. I told him to take his time in putting the kit together and it was Christmas so I wasn't in a big hurry. Some time later I received my kit. To be honest I had never seen this version of the PM224. It seemed to me the VAS stage was different and there was no facility to separate the power feeds between the output and front stage. I went about building the amp module and tested it and all was awesome! I put it on a shelf and went about collecting and making the different parts for the amp.
There is a diyaudio Soft Start and Speaker Protection kit, as well I created a custom, multi-capacitor bank (akin to the old adage that many are always superior to the equivalent of the one). I always wanted to try a CRC based filter and I'd been exposed to a lot of different PS configurations in my job as a cnc/electronic technologist and decided to try a combination of CRLC. I've used CLC filters and I thought maybe there was a best of both worlds here.

well most my parts collection was completed about 2 years ago but I fell ill and all went on a back bench. I've been poking away at it lately and my god I'm actually getting somewhere. I got at least 60 taps completed in each of the heatsinks and parts positioning has been worked out other then one small transformer. It's taken quite some time and I've had help manipulating the larger/heavier parts. the transformer is a 25-0-25 500va Antek and I incorporated some parts from a CA-150.

I created custom 2mm copper heatspreader/anglebracket for them and I've had a bunch of these massive heatsinks I bought off a dude on the east coast many years ago (that was a MASSIVE shipping bill). I think each weighs about 20 lbs!!! and the trans weighs a ton also. I'm gonna have a friend put this on a small wheeled stand for me so I can move it around easier.

enjoy the photos and I should have this complete soon, it will remain my focus till this happens (I have too many projects going here, I gotta finish some!)

Hello friends,
i need to replace my OW1 tweeter in my carrera speakers and i dont want to change the crossover
i get get from friend two Satori TW29TXN-B-8
do you think it will perform well without changing nothing in croosover ?
thank you

Hi all,

So I own this player. Sadly when I wanted to use it after a year it has problems.

First of all it will randomly stop spinning. I can somewhat force it by skipping tracks, after a while it will stop when next or previous is pressed. But it happens during play as well.

Next it sometimes starts sounding garbled, also randomly. I feel this is related to the spinning issue, it might be spinning too slow.

Lastly, it randomly skips. Cds ate fine and next time I play the track it can be fine.

Is this a motor problem? Or something in the motor drivers? I'm not sure, cd players aren't my field of expertise.

Anyone care to chime in with thoughts?

Kind regards,

Bert

While trying to fix a family members dead sub my Presonus Eris Sub 8 has decided to mimic gale force winds for some reason. I checked everything from trying a different wall socket, removed inputs and outputs, and checked to see if the volume has any effect (it doesn't)

I have read that the cause is likely a leaky DC filter capacitor which would make sense, but I don't have a schematic for this power supply and don't know my way around them well enough yet to know which might be the likely culprit.

I did also notice a few dry solder joints but would they cause the issue?

First a picture of the finished beast on the scales (it weighs 26 kilos with batteries).



Then a couple from the testing where you see both sides:







The design parameters for this was to make the optimum comprimize between several things. These being:

- best possible sound quality
- loudest possible output
- longest possible battery life
- lowest weight possible
- smallest volume possible
- lowest cost possible
- simplest possible construction

Since I wanted low weight and high output I very early settled on a design with 4 10" pro woofers mounted magnet to magnet inside the cabinet to give added sensitivity and free structural strength which meant I could use thinner plywood than would normally be used for baffles. I also quickly settled on 7 layer 12 mm filmed birch plywood, both because we have a lot of it at work and because it very very rigid.

I used 4 P.Audio HP10W woofers becuase they're cheap, sounds great, and not least because they had the perfect depth for magnet to magnet mounting. For top end I used 4 MGR CH-100 piezo tweeter. Again low cost and good sound quality was the primary factors. It's not really filtered, it's got a 0.22 mH coil to flatten the peak of the woofers and filter above that point. The piezos only has 3 Watts 150 Ohm carbon resistors in series. With a 150 Ohms resistor, they sound great as long as the voltage across them is not too high.

The cabinet is built as two separate bass reflex cabinet with a battery and electronics compartment in the middle. The holes on the front are cooling and cable access, while the handles on the sides double as reflex ports.

It's designed to be used outdoors, so I chose a Qbox of 1.1 tuned at 82 Hz (my little nod towards 41Hz.com ). Trying to go belong 100 Hz in free-field is nonsense if you keep the other design parameters in mind. It's better to have a good middle bass performance to compensate for the lack of real sub-bass.

It's loud! The sensivity is about 98 db/watt because of the double woofers and the magnet to magnet construction. With the amp giving about 50 Watts total peak power output, it should be around 113db total in peaks.

The choice of amplifier was pretty obvious. I had to be a Tripath based amp because of the low cost, good sound, and long battery life. The choice fell on the excellent amp6basic kit from www.41hz.com. Here shown with and without cooling plates. (I made two beasts at the same time, one for me, and one for a friend of mine.)





The optimize battery life I installed 4 8 Volts 250 mA solar cells from siliconsolar.com, 2 in series on either side. The battery life solely on battery is around 50 hours at maximum music power. And with reasonably sunny weather, they can probably last several months at fairly normal power levels. That remains to be tested.



I also added a switch mode recharger from batteryspace.com, and a standard car USB power supply. The batteries are 2 standard 12 Volts 7 Ah SLA paralleled and stacked on top eachother.

Here's a few more pictures from when I put them together.





Cheers!

Time to clear out a few things that I will not be using, and the first is the complete balanced version of the Iron Pre, including the initial offering and the completion kit. I am asking $325, including shipping via Priority Mail flat rate box in the U.S.

Thanks for looking. I'll try to get quite a bit more out in future listings soon, including a few "specialty items" that would require pickup in Wisconsin. (Danley SH50s, anyone?)

What are the requirement for the VAS driving a MOSFET source-follower OPS? Currently I'm trying to design my first MOSFET poweramp, aiming for about 20W RMS using lateral MOSFET:s (very low power for these output devices, but I have a 2x18 V transfomrer I intend to power it with). Basically what I've done is that I used the design from an other amp I'v built and "just" replaced the the OPS with MOSFET. Spice simulation gave ok results.




But then I thought, since MOSFET OPS doesn't need that much current, maybe I can use a simplier VAS? The benefits of this Darlington-arrangment basically only applies then using BJT OPS, which requivere quite high currents (?). So I tried it in Spice too. This time with only one transistor. I had to increase the current for the input stage, since it takes more current to drive it. But what I found interesting is that it did performed about as good as the Darlington arrangement in terms of distortion and slew rate, according to Spice.



The results from Spice simulation is quite impressive, around 0,001 % THD @ 1kHz 1W into 8 ohms, increasing to about 0,03 % at 20 W. Though, I doubt that the actual amp will perform as this good if I built it.

So could I use the single transistor VAS instead, or is there anything else I'm missing here?

Hi Guy,
Is anyone using these mesh tubes ? Would appreciate your thoughts.
Am running mine on TJ Mesh for a couple of years & they sound real good to me.

Thanks

Logitech 2.1 bass is too heavy - Will replacing the pot with a higher value fix it?

I submitted this post a few days ago but I guess I didn't provide enough information for anyone to respond. Also the pictures I provided had glue covering key components. -Sorry!


So let me try this again.

First of all, I'm not very experienced with electronics other than soldering obvious things like broken traces, loose resistors, capacitors etc... To give you an idea, I have to google Ohm's law everytime I need it.

Also, I know these are ridiculously cheap speakers with most-likely designed with a planned obsolescence, but I do love them

This time I made a detailed wiring diagram (click to enlarge):




Despite keeping the subwoofer level volume all the way down, they've always tended to still be a little boomy in the bass, which I would fix by rolling off the lower frequencies in winamp's EQ.

I would really like to fix the bass problem at the source so that I don't have to compensate via software, especially for connecting them directly to a tuner/mp3 player.

The subwoofer level control is a 10 kOhm linear taper pot that has all three legs leading to somewhat complicated (to me) circuits:

Both Leg 1 and Leg 2 (wiper) of the pot connect to the upper two opamps of the TL074CN from opposing directions via an array of resistors, capacitors and a couple of diodes. It really does look like they are opposite sides of the same circuit. I'm guessing that this circuit is the preamp for the subwoofer alone since you can see where both the left and right channels lead into the lower half of the TL074CN for the satellite speakers.

Leg 3 leads to the one of the outputs of a JRC4560D opamp.
The negative input for that amplifier gets fed from both the left and right input channels. The positive input for that amplifier comes from the two upper (subwoofer) opamps of the TL074CN via a complicated route that is connected to the base of the lone 2N3904 transistor.

Is the JRC4560D some sort of active EQ circuit?
If so, is it already defeated when the knob is set at "0" (as it always is)?

As you turn the subwoofer level knob up, does the pot simply apply the output of JRC4560D to both of the other Legs (1 and 2) in order to boost the bass?

If this is the way it works then it seems like my original idea of simply increasing the resistance of the pot won't work because the pot is already all the way down at zero.

Is there another solution that would (slightly) decrease the bass? Perhaps there is a resistor on the board that I could replace?

Thanks in advance for any expertise you can offer.

Hello,

I purchased AJ Horn and i can work everything great. i now wish to build these but the only folding program i can find uses horn response which drives me insane.
When i simulate a tapped horn in Horn Response 1 of two things happens.
1) the driver is in the wrong spot and i dont know why
2) if the driver is in the right spot, switching to acoustical power shows a very similar response to AJ, but when you try find max spl, any voltage (as low as 1volt) then turns acoustical graph into a weird W shape. i then switch back to input parameters and hit calculate and the response goes back to normal.

If anyone can help that would be of greatly appreciated.
Here are the settings.
in case i have input something wrong, the beginning of the horn is 50 sq cm and the mouth is 232sq cm and is 3250 long.

Thank you

I have been sitting on a bunch of 6P1P-EV for years that I paid next to noting for.
Always assumed they were close to a 6AQ5 in capability and so never really found a use for them.

As electrically the 6AQ5 and the 6V6 are pretty close this got me thinking what could these old 6P1P really do.
I made up a chart to compare some basic physical and electrical parameters.
Thought I would share my data in case anyone finds this of interest.


Heater power, a reasonable proxy of the cathodes ability to emit electrons is close in all three, the 6P1P a little better @ 109% of the 6V6.

Maximum anode voltage on the data sheet shows the 6P1P-EV limited to only 250V but the anode data curves extend up to 475V or 118% of the 6V6's 400V on the data sheet.
Does this mean anything? Perhaps as there are many motivations at work when a data sheet is written.

For heat dissipation surface area can be a reasonable proxy for total power dissipation all other factors being the same. I admit I do not know what exact materials the 6V6, 6AQ5 or 6P1P are made of.
I found it interesting that the 6AQ5 anode area is only 71% of a 6V6 and the 6P1P is closer but still smaller at 85% of a 6V6.
The area of the glass bulb affects total power dissipation and here the 6AQ5 is 43% of a 6V6 and the 6P1P is much better at 71% of a 6V6.
All three are rated at 12 watts of anode dissipation but it seems to me perhaps different sized watts were used with the 6AQ5 data sheet and the 6V6 is old school conservative.

S (mA/V) is close for all three with the 6P1P being 119% of a 6V6.

The bias point with 250V screens is virtually the same 44-45mA anode current at -12.5V on g1.

Peak plate current at a=100V is again close, a 6AQ5 @117% of a 6V6 and a 6P1P @99% of a 6V6.

A stand out difference is rated G2 power. The 6AQ5 and the 6V6 both at 2 watts, the 6P1P @1.3 watts or 65% of a 6V6.
Suggests if you want to push a 6P1P it is best to carefully watch the screen voltage and current levels in your design. Limiting the peak screen voltage and current when the anode voltage drops at the bottom of the output waveform is going to be important to keeping a 6P1P from screen death is seems. This suggests a limiting factor for maximum power that can be pushed out of a 6P1P will be screen power levels.

On one hand the 6P1P seems closer in ability to a 6V6 than a 6AQ5 when physical size is looked at.
On the other hand the low 1.3 watts screen rating on the 6P1P does suggest that 6AQ5 power levels maybe all there is before the screen fails.

I would like to hear from anyone with direct experience in pushing 6P1P tubes to levels closer to 6V6 power levels and above 6AQ5 power levels.