The solder/solder fume extractor threads lead me to search for an inexpensive adjustable arm to mount a 40mm axial fan to. I recently salvaged one from a dead NVR and It's dead quiet at 9-12V, with nice, gentle airflow. I figured it would be a huge improvement over the 4" fan that I'd tried in the past. Under-volting it was fine, but positioning wasn't ideal.
In any case, I was lead back to the multi-arm stations that I'd considered in the past. Have any of you tried This particular unit ?
If so, I'd love to hear your thoughts

Hi All. I'm about to make another push-pull power amp (100W) and was wondering if I should have fuses on the supply rails (+-50V) Currently I have an amp that I made and simply have the DC supplies DIRECT from the main power supply. I do however have a LS protection board on it. My thinking is that the fuses (Fast/Normal or Slow?) is that they introduce quite some resistance (non-linear?) to the supply and spoil the very solid 40,000uF I have on each channel. They are, after all, just lengths of very thin fuse wire and I use silver-plated thick connecting wire for minimum resistance. What are the thoughts on these fuses please? I am tempted, as usual, to leave them out. The way I see it is that the only time they will blow is when one or more of the O/P transistors blows (or maybe just a smaller component) and they will in themselves, act as fuses? If any component does blow/burn out it will need replacing anyway so nothing has been saved by the fuses. PS: I will use them for the first powering up session.

Funny, I'm raving about the sonics of my Radian 850PB and people
keep contacting me about the Yamaha JA-6681.

Because I think that this driver deserves it's own thread
and because I don't want to keep answering the same questions over
and over again, here are some facts and thoughts:

Yes, that thing sounds absolutely fantastic.
Altec, JBL, B&C, BMS....no contest.
TAD? I don't know, I never heard one, but prior to my purchase I contacted
three people who possessed both drivers and two of them preferred the Yamaha,
while one said they are equally good but different in sonic signature.
Take it for what ever it's worth. YMMV.

It's not an alnico magnet driver despite the look. It is actually only a
1” driver with a cast aluminum conical extension. In fact, the cheap
looking Yamaha 6603 driver is identical except for the phenolic diaphragm
and the missing conical extension. If you know how to correct shifted
magnets, and you want to use a tweeter anyway, there is your chance.
I'm using my 6681 with the phenolic diaphragms and I think they even
sound a bit more organic, if you know what I mean.

No, there are no diaphragms out there anymore. Money, or a friend
who works at Yamaha etc. will not get you any diaphragms. Zero. Nada.
You could get some from Meyer Sound and carefully scrape that stuff off
from the Copper Beryllium suspension, butt $$$$$.
Or you rent some Meyer Sound …...ups I killed......
OK,OK, just kidding.

Yes, it can give output from about 250hz on up, but who would want to do that.
Remember, there are no diaphragms anymore and one mistake is all it needs.
500hz first order to a good paper cone sounds more natural anyway and the
radiation pattern up high is way better.
I would still use a good tweeter, even with the aluminum diaphragms, as it just
adds that extra ambiance and realism and because you will not be stuck to a one chair
sweet-spot. It's just allot more fun to listen to good music with some friends
and nobody is missing a whole octave which makes a big difference.
That's actually why I prefer a slot tweeter instead of the normally used bullet.

Anyway, I think this is all about the Yamaha JA-6681 that is relevant.
If you have any more information about this driver please feel free to
add it below.

Greets,
Klaus

I am looking for a pair of either of these tweeters.

I have both a US & Canadian Mailing Addresses and will pay via Paypal (US) & EMT & Paypal (Canada).

Let me know what you have!

Looking to buy a Pair of Morel CAT338 Horn or Wavecor TW030WA12 Waveguided Tweeters

Also looking for Dynaudio D28 / D21 Waveguide / Horn Tweeters

I am looking for a pair of either of these tweeters.

I have both a US & Canadian Mailing Addresses and will pay via Paypal (US) & EMT & Paypal (Canada).

Let me know what you have!

FS: 12AU7 Tube preamp - Bottlehead Foreplay circuit, complete and functional, uP controlled (Basic Stamp). One of my first tube preamp, made with love and care, all point-to-point with quality parts, ground bus, and a nice part of NOS RCA 12AU7 tubes. Just the tubes still sell for about 100$... Chassis is made of oak. stained red, solid steel top and bottom plate. Weight 18Lbs! so shipping of a large box, well packed will probably be around 50$...

You won't find a nicer little tube preamp, well made with quality parts, at a better price...

You'll get all the documentation, schematics, and the Basic Stamp controller code. You can modify it as you wish. Processor programming accessible from the DB9 on the back. Remote control code is included, as well as the motorized ALPS volume pot. I never completed the IR receiver and decoding code, there is still a few bugs. The rest of the code is working fine if you don't try the remote...

Front buttons: Power-On/Standby, Mute and source selection. Four inputs, one output, one Tape output (parallel to the selected input).

Asking 250U$ o.b.o + shipping + Paypal fee.

For Canadian the preamp is also listed on CanuckAudioMart 350$CAN + shipping, local pickup is welcome, as well as EMT direct bank transfer, or cash in person

Let me know
Thanks
SB

This looks like a fun project, anyone tried this clone from eBay, it looks like first class pcbs

Hi

I am new to this brilliant forum (can't believe I never found it before).

I have for the past 6 months been heavily modding my CD63 KI and the results have been fantastic.

So I have turned my interests to the KI amp.

So far I have changed C705/706/751/752 for equivalent Black Gates

C717/718/719 for uprated Black Gates.

C709/710/753/754/755/756 to equivalent silver mica types

The results have been very good indeed, bringing new life to the amp.

I was wondering if anyone here has done similar mods and has any more pointer for me.

cheers

Last month at the Burning Amp Festival, I presented a little PCB called BJT Simple Matcher. That BAF talk, plus some photos, the matcher schematic, and the PCB Gerber file, are available on the diyAudio Forum (here). At the very end of the talk, I showed a little example circuit which greatly benefits from BJT matching, named "Yes It Can Drive an F4" (revision A).

A couple of small tweaks later the newest release (rev B), which I hope is the final release, is presented here in this thread. You can see a top view of its unpopulated PCB, and also the circuit schematic diagram, in the attachments below.

WHAT IS F4 AND WHY DO I MENTION IT HERE?

F4 is one of Nelson Pass's many FirstWatt amplifiers (link). Unusually, the F4's circuitry is arranged as a Unity Gain Buffer: although F4 provides enormous current gain, its voltage gain is only 1X. To get the maximum available output, 20V (peak), you must supply an input of 20V (peak). A large number of DACs, streaming devices, smart phones, and linestages are unable to swing their outputs to 20V (peak), so these are not a good match for the FirstWatt F4.

In fact, it is so rare to encounter a line level device which CAN swing its outputs to 20V (peak), that a snarky catch phrase has arisen here on diyAudio:
I'm pleased to report that the little example circuit presented here, gives an affirmative answer. Yes it can drive an F4. Yes it can swing its output to ±20V (peak).

The board is designed to be installed within an F4 chassis and to use the existing F4 DC rail voltages, with NO modifications of the F4 power supply or the F4 amp channel. Just bolt in the new boards, one per channel, and wire them up. Done.

DOUBLE DECKER / PIGGY BACK MOUNTING OPTION

This circuit board is 50mm X 90mm; its mounting holes are 40mm X 80mm. Which is a perfect match to the left hand (or right hand) set of four mounting holes on the F4 PCB: 40mm X 80mm. Using spacers, you can mount it directly atop an existing F4 PCB, in Piggy Back (Double Decker) fashion. Please see the attached photographs.

An F4 amplifier channel board (blue PCB) has a Yes It Can Drive An F4 (black PCB) mounted directly above. The spacers in this picture are 20mm tall (M3 female, hex body, M3 male) but Amazon also sells 25mm tall spacers if you prefer longer. The male ends of the spacers replace the M3 screws which secure the F4 amp channel to its heatsink.

Of course, builders are free to mount their Yes It Can Drive An F4 boards wherever they wish, in whatever orientation they like; there's certainly no requirement to use the piggy back mounting scheme.

YOU CAN ZIP-TIE Q5 AND Q9 FOR BEST THERMAL CONTACT

I've arranged the PCB footprints of the matched pair Q5-Q9, so you can zip tie them together (face to face) before stuffing and soldering. Personally, I solder all six legs and then cut off the zip tie, before I scrub the board with 99% isopropyl alcohol to remove flux and grunge. See the attached photo with a thin red arrowhead that points to the matched pair of transistors.

After I'm all finished with IPA and other solvents, then and only then do I apply a dab of heatsink thermal grease between Q5 and Q9. Finally I zip tie them back together again. This time: forever.


CIRCUIT DESIGN OF YES IT CAN DRIVE AN F4

The main goals of this board are (i) to use and to exploit tightly matched BJTs, thanks to the BJT Simple Matcher from BAF 2024; (ii) to provide high gain and wide output swing -- 20V (peak) -- without any shenanigans or funny business on the power supplies. Just use the same ±23V rails as the amp channel, and be able to swing > ±20V on the output.

Goal (i) is met by choosing Q5 and Q9 in the circuit, to be a pair of tightly matched BC546C devices. The schematic asks for matching within plus or minus 0.3 mV; but in the real world you'd just test 30 or 50 NPNs and then select the two pairs with best matching (one pair for the Left channel, one for the Right). If you can't quite get 0.3 millivolt matching, it's not the end of the earth. And if you can get better than 0.3 mV matching, how lovely for you.

Notice that there is only one capacitor in the signal path: input coupler C1, a high quality polypropylene film capacitor by Wurth. C1 blocks any DC offset that may be present on the input ("J6") from polluting the circuit and its output.

The circuit is designed to drive an F4, which includes a pair of AC coupling capacitors between the F4 input buffer and the (large) F4 push-pull output stage. Therefore I have omitted a coupling capacitor at the output of Yes It Can Drive An F4; one is already installed, on the F4 amp-channel PCB. If anyone plans to use Yes It Can Drive An F4 in a completely different application, without an F4 amp-channel, they ought to think very hard about whether or not to AC couple the YICDAF4 output.


CIRCUIT DESIGN: PART 2

Yes It Can Drive An F4 is a two stage amplifier; the first stage is (Q5+Q9) with (Q6+Q8) current mirror load. The second "voltage amplifying" stage is (Q10+Q11) with Q12 constant current load.

Because it's a two stage amplifier taking its output directly from the collector of the 2nd stage, the circuit is not able to drive a low impedance load. But that doesn't matter since the F4 amp channel board is a high impedance load. It's 100K ohms, which is easy to drive, even for this scrawny two stage amplifier.

Bias current for the two amplifying stages is provided by reference current generator Q3, which drives a first current mirror (Q4, Q7) for the first stage, and which also drives a second current mirror (Q4, Q12) for the second stage. The bias current flowing in Q3 is set by zener diode ZD1 and emitter resistor R6:

IcollectorQ3 = Iemitter = (Vzener - VBE) / R6

Plugging in numbers, Icollector of Q3 works out to be approx 2.7 milliamps. Oh by the way, after enduring the tenacious, obstinate, unrelenting "recommendation" of member @6L6, I eventually installed a pilot light LED "D1" in this 2.7mA current path. When power is applied and current is flowing, this LED lights up and reassures you that the circuit board is properly connected to the supplies.

The first stage's bias current is just a resistor ratio multiplication of the reference current

IcollectorQ7 = IcollectorQ4 * (R7 / R11)

In the same exact fashion, the second stage's bias current is another resistor ratio times Ireference

IcollectorQ12 = IcollectorQ4 * (R7 / R20)

It's illuminating to notice that the second stage transistors which drive the output (Q11, Q12), can EACH swing almost all the way to their respective supplies, VTOP and VBOT. Other designs for the second stage constant current source (Q12 here), cannot swing nearly as close to the CCS supply. The current mirror topology is the king of this particular hill.

I have specified the ultra fast and ultra low capacitance diode 1N4151 for position D2. Its part number is exactly 3 greater than the ubiquitous junkbox diode 1N4148, and indeed these two diodes are blood brothers. Diodes whose final eTest measurements are excellent, fall into the 1N4151 bin. And the rest of the diode batch, the average and the mediocre, fall into the 1N4148 bin. I think it's a Good Idea for serious DIYers to have a bag of ten or twenty 1N4151s in their parts cabinet, for those occasions when a super fast or super low capacitance diode, matters. But if you disagree, if you don't want to spend 20 cents on a new diode part number, by all means please feel free to use 1N4148s instead. The circuit's performance will suffer only a very small amount.

FOR EXPERT DESIGNERS: GAIN-BANDWIDTH, SLEW RATE, AND INDUCTOR L1

Yes It Can Drive An F4 uses an extremely well studied topology with (at first glance) completely standard Pole-Splitting "Miller" compensation. James Solomon's 1974 tutorial article (link) models it quite well; we can populate Solomon's equations by inspection, yielding the circuit's gain bandwidth product and slew rate:

GBWP = { 1/[(1/gmQ5)+R10] } / C5

SR = IcQ7 / C5

thus GBWP = 9.0E7 radians/sec = 14 MHz

and SR = 100 volts/microsecond.

Now let's consider the effect of the inductor L1 in the "tail" region of the Long Tailed Pair, Q5-Q9. This turns out to be quite an old idea; according to Scott Wurcer here on the DIYA Forums, Richard Burwen of Analog Devices used it in 1966(!) on the hybrid discrete opamp "ADI121", shown in the attachments below. Later, Deane Jensen was able to take out a patent (US 4,287,479) on the same circuit. I've snipped out "Figure 3" of Jensen's patent and attached it below.

At very low frequencies, the inductor acts like a short circuit, so the emitter degeneration resistors R10,R13 are removed from the circuit at low frequencies. This has two benefits: (i) the noise contributed by R10 and R13 is eliminated at low frequencies; and (ii) the effective transconductance of the long tailed pair stage is greatly increased. In this circuit, gm rises from 2.4 millisiemens to 52 millisiemens -- a growth of 20X (26 dB). There is 26 dB more gain available at low frequencies, thanks to the inductor. That's 26 dB more negative feedback for distortion reduction. And, oh by the way, the Gain-Bandwidth Product increases by this same factor of 20X at low frequencies. It rises from 14 MHz to 280 MHz. Cowabunga.

I encourage expert readers to derive expressions for "f1" and "f2" (the pole frequency and the zero frequency introduced by inductor L1). I think you'll be pleasantly surprised at how high these break frequencies actually are. I think you'll be delighted at how much extra gain / distortion reduction is made available at 20 kilohertz. All for the cost of a single inductor.

DON'T DO ANY OF THE FOLLOWING, THEY ARE BAD IDEAS

First: I have set the gain of Yes It Can Drive An F4 to 20 volts per volt (+26 dB). An input of 1 volt (peak) produces an output of 20 volts (peak), which is the maximum input signal allowed by an F4. Don't attempt to change the gain unless you really know what you're doing. If you need someone to help you change the gain, that means: you don't really know what you're doing. Stop now.

Second: Don't reduce the gain below four volts per volt (4.0X = +12 dB). If you do, there is a very good chance the circuit will oscillate, blowing your tweeters and perhaps also destroying the power transistors on your F4. If you need gain less than 4X, switch to a different design without this limitation.

Third: Don't put this circuit into an amplifier that is wildly different from the standard, stock F4 as documented by Nelson Pass. In particular, don't run at supply rail voltages greater than 29 volts. Neither the transistors nor the capacitors will survive at higher voltage; you will need to design a new circuit with different components and possibly different topology.

Fourth: Don't drive a load impedance less than about 25 Kohms. If you NEED to drive a lower impedance load, you will need a different circuit. This one is designed for the F4 which presents a high impedance load.

Fifth: Don't experiment with other values of inductance. Either use 680 microhenries (choose an inductor whose self resonance frequency is the highest Mouser will sell you), or else omit the inductor entirely and don't stuff or solder anything into the L1 footprint on the board.

Hi Folks,


I'm a newbee regarding the picking of certain part types for certain applications. The probably basic questions came up when I read "somewhere", that filter caps right after rectification should not have low ESR:


- In which cases/applications should low ESR caps be used?
- In which cases/applications would "higher ESR" caps be the better choice?
- In which cases/applications it simply "doesn't matter?


Thanks for some enlightment with explanations why.
Regards,
Winfried

I remember few days ago a member posted the build or their dac with Neutron Star clock (2 or 3, i don't quite remember that) and the power source for the clock was a custom DIY board (one of the power supply boards from DIYA). Does anyone know what is the voltage and current expectations for the Neutron Star clocks?

Thanks.

LME49811 amplifier PCB with matched 2SC3281 NPN and 2SA1302 PNP Thoshiba output stage.
The displayed Thoshiba drivers are also supplied, price 88€.
With the supplied output bjt's powers up to 250 watt are easily achieved.
If you require power supply pcb I can supply, reach me or check by.
If You wish to view my other modules alongside with this one you can check here:
https://www.ebay.de/itm/326489444390
Tracked shipment to European union for US on request

Hello,
I have recently develop this LM3886 PA100 power amplifier it does use DC servo and the amplifier boards can also be suited
with a cliping indicator vertical board, in this thread I show this combo of a stereo system which include everything displayed
all capacitors are from Nippon and the price for this set is 110€
If you are interested in just in one of the products you can check here the power amp boards or the supply:
https://www.ebay.de/usr/rocksandsound
Or just reach me through here.

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

My Marantz cd73 sometimes outputs loud scratchy static sounds usually when first turned on and only briefly. This issue may go away for a week. Then come back again. It may not be there for 20 hours. Then it returns for a short run of torture.

Recapped, new regulators, laser current and focus coil aligned.

Tell me your ideas for this issue ?

For sale: Unique set of two High End 750 Watt toroidal transformers in sealed housing from the German high end brand Thel Audioworld.

Available output voltages are 40, 50 or 60 Volt.
With a 40 Volt configuration the transformer delivers up to 9.4 Ampere, at 50 Volt up to 7.5 Ampere, at 60 Volt up to 6.3 Ampere.

These are unique transformers that are unfortunately no longer available from Thel Audioworld. They served for almost a year in two DIY Pass Aleph 2 monoblocks, but due to marriage and children they had to go to the attic within a year and have not been used for all those years.

These transformers are fantastic for making heavy DIY amplifiers with a superb power supply.

Both transformers have some black spray paint that has leaked onto the transformers through an opening in the housing, but this is of course purely cosmetic.

The new price at the time was (if I remember correctly) around 300 euros per transformer. They can now go for 250 euros both.

Pick up near Arnhem (The Netherlands)but shipping also possible.

Each transformer weighs 6.5 kilos, but I will pack them really well.

Selling can also be arranged by Ebay account.

When I was searching in my closet for some resistors I stumbled upon two attenuators I bought years ago at Ebay...
Does anybody have a clue how to connect ?

Heres a picture:

I have been reading about coatings until I could stand the subject no more. Sigh.

Seems there is very little consensus out there and quite a few secrets :-(

Mind you, I do appreciate the effort that some people put in in finding a good solution for this problem, and I fully understand if they want to keep their secrets. Besides it is their right to do just that. And there is always the risk that some company would want to run off with the formula and patent it. Talk about scr*** the inventor!

So I have absolutely nothing against secrets!

Having said that, I prefer to use a public domain solution (if at all possible). I like the idea of being able to reproduce my efforts at some other time (or by someone else) without the problems of having a supplier going out of business, or being bound by a promise for confidentiality.

Thus the coating is reduced to the following possibilities that I know of:

1) Graphite rubbing
2) Nylon in methanol
3) Glue
4) Elvamide (possible sourcing problem, better to use option 2?)

How are the experiences with any of the above?
Which one seems best for quality and long term stability?
Are there more solutions (pun intended!) for this?

Hola, soy Bran, tengo 20 años y me gusta el audio, sin embargo compré un amplificador de tubo muy extraño y quiero saber más sobre él.

One done. One to go.

Objective: Duplicate a vintage Tangent Acoustic RS2 using NOS/Currently available drivers

Intent is to a) first build a copy of the original speaker, and compare it vs the original. If it comes close enough then to experiment with alternate drivers for the 8" woofer, while utilizing the commercially available T27 tweeter.

Equipment on hand:
1) 2x Tangent Acoustic RS2 speakers
2) 2x T27 Tweeters, new from Falcon Acoustics
3) 2x NOS Audax 8" HD20B25J driver (the OEM driver for this speaker)
4) Umik-1
5) Dayton Audio DATS
6) Some free time here and there
7) Lots of enthusiasm

Plan:

1) Cabinet to be built as per the original spec, Of what I understand it's birch plywood with an MDF front baffle. No internal cross bracing, 1-1.5 inch foam padding all around. The drivers are mounted directly to the baffle. Status: In-work, Have opened up one speaker to assess crossover. will be utilized as main reference for measurements.

2) Crossover to be replicated using currently available components. Some interesting findings to share further in the thread.

3) Objective a) Speakers on hand, pending cabinet and crossover. 😀 Easier said than done.

4) Objective b) Have shortlisted 2 drivers (for the forum's review and feedback). File names in ( )

1) OE Audax 8" HD20 B25J specs: (HD20B25H - Catalog 1982)

2) Option #1: Audax HM210C0 (HM210C0 - Catalogue 1994) (comes very close with the fs at 30hz vs the 27 +/- 1 of the OE Audax)

3) Option #2: (slightly smaller) Scanspeak 18W/8424G00 (18w-8424g00)


Other drivers in consideration; Visaton BG20 (sitting by my desk), Visaton W200 (Also sitting here).

Disclaimer: I am not well versed in speaker determination, but I can match numbers better than my kid.

First up, Umik 1 freq response measurements of stock speakers. (1/6th octave smoothing).








Be right back. Bedtime for kids.

Hello, I have stupid ideas, and I'm ready to be told they're dumb

Hi everyone thanks for having me! New to hi-end but I come from coffee where measurements and snake oil reign supreme! With some help I should be on the right track to audio bliss! Have a nice day!

Hi everyone,



I’m working on a custom audio build that combines an R2R DAC, an Aleph 1.7 preamp, and a power amplifier inspired by the Dartzeel NHB-108, all inside the same chassis.



Given the mix of digital, analog, and power circuitry, I’m trying to carefully plan the grounding strategy to avoid ground loops and noise. I’ve labeled every GND point in my design and created a PDF diagram showing all connections, supplies, and ground references. Each GND is numbered to make it easier to follow.

---

🔧 What I’m asking:



I’d really appreciate some help figuring out:

• Which GNDs should be connected together?

• Where should the central ground (star ground) be placed?

• Which GNDs (if any) should be isolated (e.g. digital vs analog)?

• How to properly handle speaker return ground in this context?

---

The PDF diagram is attached to this post.

Any suggestions or guidance would be hugely appreciated!



Thanks!
Daniele

Hi, I know this is a bit of a long shot, but I could use some help on where to start looking for issues so I'm hoping someone may have a guess based on ...very little information.

I have a pioneer d23 active crossover driving 3 way active. A few months ago I replaced all the electrolytics in a successful attempt to repair an issue. I've been using it without issue since then until last night I went to listen to music and got some mild volume from one driver only, everything else silent. After fiddling around a bit I now have no sound from any drivers. It's definitely in the crossover as preamp directly to driver amplifiers works fine.

I'm completely at a loss as to where to start. Powers on fine. I can't see any physical issues. I assume it can't be in any of the individual crossover boards or the whole thing wouldn't just not produce sound at once...

So I know it's not much info but I'm just hoping someone might be able to eat "it's probably xxx" or "check continuity on yyyy" because I'm unskilled and baffled

I Have a copy of the schematic but hifi engine seems to be down for a web version.

There is a version here that requires a few steps...

https://elektrotanya.com/pioneer_d-23.pdf/download.html

Tia for any advice or thoughts

Hello all,

As hinted at here and there, Mark has some new drivers on the horizon in the Alpair range.

18 months ago after we successfully released the Pluvia range of drivers, which have been well received, Mark set about the next design evolution. As some of you will know Mark's design ethos is mechanical efficiency, adding lightness and simplifying where possible. In these new drivers Mark has managed to achieve much more with much less.

One of the things that frustrated some of Mark's previous design efforts was the rear suspension being a pain in the ***. The necessity of it leading to design compromise. Freed from the necessity, drivers could be lighter, have tighter production tolerances and could be much more linear through the whole excursion range.

For these new drivers Mark has spent countless engineering hours trying to engineer out this need, not only did he find a solution but it helped him solve another long held desire - greater dispersion. For a long time now the drivers have used Aerospace grade alloys for stiffness, allowing shallower cone profiles. The multiform cone pressing process has allowed Mark to use complex cone profiles to enhance the stiffness further and increase dispersion. The new cones take this concept even further.

The removal of the spider means moving the centre of gravity of the whole drive train so that it can balance without the need for the spider at that centre. Removing the spider allows space for the magnet and the coil/former to move forward which helps, but the cone needed making shallower still. The answer to this answer also answered the question of increased dispersion as well, thus killing two birds with one stone. The new cone is negative camber, so not only is it very shallow but the outside edge actually comes back on itself.

The results of this new engineering leap are presented in the all new Alpair7 MS and big brother Alpair 11 MS where MS stands for Mono Suspension.

I've attached a teaser image here and over the next week or two we will get the PDF's uploaded for mass consumption and Scott will be working up some box designs as usual. the A11MS fits straight into a Frugal Horn XL acoustically although it is a little larger so modification will be needed. The 11 also does work in the Pensil 11 although the alignment isn't quite optimal, Scott is working on either a new design or a way we can all modify an existing cabinet, there will be other designs and obviously the A7MS will get the same treatment.

To start with these will be in VERY short supply but rest assured over time stock will increase and obviously the current drivers will still be available for some time to come as well.

The weird speaker in the picture below is an updated version of an active 5-way speaker I built about 15 years ago. I wasn't happy with the DSP/amplifiers in the original design, so I stuffed them in a closet until I could finish off new electronics.

Each octagonal "tier" has 8 drivers, and I had wired them so that I could reverse the polarity of the drivers in the back. The original design used relays to reverse the polarity, but in this updated version the polarity is controlled by processing in an ADAU1466 DSP. This approach requires 10 power amps for each speaker, with one amp for the front and one for the back. The DSP processing for the dipole switching/compensation is shown in the SigmaStudio snippet below. Each of the rear drivers has a signal inverter plus a biquad for a shelf filter, plus a gain block to adjust the volume.

I only have one speaker running right now, but I'll get the second one working as soon as we finish refurbishing our upstairs bedroom. I've only got this one speaker running in a small workroom, and there is still a lot of work to adjust the delays and experiment with different crossovers. However, the difference between dipole and monopole mode is fascinating.

I know...the lights are kind of weird, especially when they are flashing to the music 🙂

As mentioned in the thread. Looking to buy an Andrea Mori Dac/Fifo and or clocks.

Thanks in advance!

Seb

Over time I've occasionally seen the position advanced that piezo tweeters can be pretty good, but you have to filter them the right way. I haven't heard a fancy pants piezo setup, so I've kinda wondered if it's true. A while back I saw some closeout piezos of the 2x5, 1016 type. They were super cheap, so I ordered 10. They lay dormant in my garage for a time, but now 2 of them will spring forth into a 6" 2-way to sing the song of their people. But can I get it to sound nice?

These will partner with a 6" buyout driver I got some long time ago. It's a buyout that says Taiwan 13014690W. DATS measurement and a modeling says 10L, sealed, f3 ~60 Hz.

So the first thing I did was make up a test baffle and measure all the piezos on it. They start at about 3 kHz, and the biggest bummer I think is the variability 7-10 kHz where there is some sort of resonance. I chose 2 examples that are nominal / matched. All 10 and the selected 2 shown below.

I have several thousand of these old non magnetic Holco resistors.

I originally bought them because I wanted some specific values.

I’m just testing the audience. Is there an interest in me listing those surplus to me? The price will be $1/pcs, min 50 assorted or one type, plain non-registered envelope. $5 in fixed shipping cost.

Of course if someone wants a substantial amount, reduced price and registered shipping will be made available.

Thanks for looking.

R

Hi

I am trying to fix my Azur 840E Preamp from Cambridge audio. Some of the resistors are damaged and needs to be replaced. Problem is that they are burnt so bad that the color code is no longer visible.
Therefore I was wondering if anybody on this forum have the scematics or the service manual for this preamp?
Any help is appreciated 🙂

Regards
ohmsweetohm

Hi guys,

some good news on the ARTA homepage. Have a look

Mateljan personal page

Does anyone have two bare pcb for wolverine power amp?
Only shipping from europe to italy. Unfortunately italian customs is very slow so I prefer to buy them from eu.
Thanks

The Singing Bush Tips 'n' Tricks, so even Cheerleader Girlie can build it ...

....OK , here it is

ORIGIN THREAD : The Singing Bush


First few posts with graphical info, then I'll write separate posts for both amps, explaining few details


////////

however , most important thing when starting, applicable for both amps:

be sure that trimpot in buffer negative rail (lower JFet group source) is set to max position, prior to first powering up - check that measuring across parallel 39R resistor - reading must be close to 28R

/////////

another thing - remove that silly blue collar from needle wire terminal you got from me - either use heat gun or heat it with solder or lighter ...... then pull it

all wires need to be crimped then soldered in wire terminals, then heatshrinked, to look nice

///////// ( you can see from these slashes that I spent some time recently struggling with Arduino )

for 2SK77B - lucky bstrdz having these - all 3W resistors in Mu part of amp - they are still 1R/3W , no change ........... Iq 3A2, output node or SIT Drain (what's easier to reach for measurement) set at approx U/2

///////////

edit 27.07.2020. - SIT Singing Bush startup procedure , post #29

We have previously published a Simple Speaker Protection (SSP) for amplifiers with balanced outputs :
https://www.diyaudio.com/community/...power-amplifier-with-balanced-outputs.244157/

But how about Class D amps with single supply and maybe also BTL outputs, or car amps such as TDA7850 ?
This is an attempt to find a single solution for all.
Not proven, but useful basis for discussions.
Hopefully someone has better ideas, or can make it even simpler.


Patrick

.

Here is a little buffer using depletion mode BSP129 SMT MOSFETs.
It will drive low impedance loads at .000% thd range. Frequency response is very extended to video range.
It needs some heatsinking or lots of copper because the current is close to 100 mA.
The circuit is the old White video buffer with silicon.

I got 4 free Kenwood KAC-51 that do not work. All four have made 2 fets burnt all in the same location.
After replacing the 2 fets and gate resistors I turn it on but only get a loud humming noise. My Oscillator shows a square wave but jumps up and down.
Im hopping if I can fix this one with your help the other 4 will have the same fix or close to it.


Thank

I have a pair of B&W DM603S3 Speakers. This started as a single tower rescue, and later I purchased a second tower in mint condition for a stereo setup.

One of the things I did was send the midrange driver to a reputable speaker repair shop. The dustcap was torn to shreds. They mounted a CM8 driver phase plug in its place and I never thought about it again.

I am currently modifying the crossovers and that phase plug revealed itself as a major issue I had let go on for years.

The phase plug was mounted to the magnet, which based on research is the correct way to do it. The stock driver has the phase plug glued to the cone and moves along with it . Theoretically the modified phase plug should provide much better dispersion at high frequencies and essentially improve the off axis response. It also explains why my soundstage always sounded phase-ey as they are now essentially completely different drivers.

This woofer has louder high frequencies compared to stock under the same crossover (ear tested without tweeter)

I want to perform measurements to see what else I can find.

Naturally I could just buy a replacement unit, trash this one, and restore parity but curiosity has the better of me and I am seriously contemplating performing the same mod to my stock unit. It would probably require a crossover redesign but I'm already in the middle of that anyways.

I will perform very very rudimentary measurements in the next few days.

Should I call it quits now and just replace the whole thing or is this something worth pursuing?

---

I made this lil bluetooth speaker! I took it to Burning Amp 2022 and a few people were entertained by it, so I figured I'd put up some info about it. Also, it's fairly clearly not fully optimized, so as I continue to work on it ... slowly ... I'll post up results here.

First! Every thread is better with pictures, so here it is.



This is what I built based on driver suggestion from Planet10 back in this thread https://www.diyaudio.com/community/threads/driver-choice-for-bt-speaker.385079/#post-6995827 -- if admins wish to combine these threads that's fine. I thought about just continuing with that thread but felt the thread name (Driver choice for BT speaker) was misleading since I've now bought the drivers and am no longer seeking input there.

So what's going on here? This is a pair of MarkAudio CHN-50, in 2 liters per side, each tuned to target 80 Hz. I'm using a Dayton KABD-250 to power them. It's cool b/c it's got bluetooth built in, nice enough little amp, and it's got DSP and uses Sigma Studio which I was excited to try out. It's also got line-in and line-out. There's a battery board that matches it, and you need to get a programmer board to work the DSP angle.

As we played with it at BA, it's got 4th order HP at 80 Hz, and some compression (dual band! yay for Sigma Studio's flexibility) and some EQ. Honestly I don't feel like I've gotten a really complete understanding of the FR yet (I've made a few measurements) so the EQ probably needs honing.

Further, BassBox said that 2 liters would take a port 5" wide and 1/4" tall and 7 1/8 inches long (with a 90 deg turn internal) to tune to 80 Hz. Impedance sweep made it look like I had hit the target, but the guy who was measuring stuff at BA took a nearfield of the driver and said he saw the port null down at 60. So I'll have to verify that and change the porting if necessary, as matching the HP and the tuning frequency to save excursion is a must. Why the discrepency? Maybe the substantial aspect ratio of the port makes it function differently at low level (impedance sweep by DATS) vs higher level (measurement, music playback)? Needs investigation.

Further Mr. Measurement was getting reasonable FR, but REW was giving him odd looking impulse. AND, he came to the conclusion that there was something funny going on, he said he could feel the off cone being driven when feeding a single channel into the measurement (connection over BT), so a few people thought something funny going on with some processing in the BT setup (as distinct from the DSP chip), so I'll have to check that out also.

Finally, if I can get everything else together, the plan is to use flexible tuning options in Sigma Studio to make a sub out with the line-out, that can switch to a higher HP optionally and feed everything else to an external sub.

So that's what's up! I got a job and a family and a house, so probably gonna take some time to go through all this, but I wanted to start a thread while the folks I met at BA maybe still had an idea of the device.

I have an Acoustic Reality ear 2 (I think) that probably has not been powered up in 15 years.
It has a pair of B&O IcePower 500A MKII boards that look fine, and a decent sized power supply
with big 10,000uF 100V caps.
I've never worked on a digital amp and am wondering should I power it up on a Variac say
90 to 100V and let the caps form?

Printed on the board is ICE500A MKII

Any suggestions?

Has anyone ever build a PLLXO with LR instead of RC Filters?

Is the any calculator to desgin it?
Many thanks

I have one and need another. Not picky.

I have the following tube audio buffer that I use with my Magnavox AMP-142 which takes a stereo signal, makes it mono and converts it to a lower impedance output as the amp is about 15' away from the preamp and to do it any other way caused extra hum and some Miller capacitance issues due to the first amp stage being 1/2 of a 12AX7.





I really don't like running an unbalanced line level signal more than a few feet even if it's a lower impedance due to the potential for hum pickup. I can make the circuit into a balanced output by doing this.





The problem is I'm not sure how to convert the balanced output to unbalanced at the amplifier itself without using a transformer.

How would I do that?

Hi everyone, I recently came upon a 400A (dismantled!) which seemed an attractive project for me.
Someone's partially completed amp, which they'd dismantled and done some work on.
When I got it home and began a parts inventory, I noticed this amp has driver boards which don't agree with published 400A schematics
and are labeled “520683 Mod II”.
I've been searching high and low since then for info about the mod, and I did find that Threshold offered upgrades to their older amps to the Stasis technology at some point.
The only other thing I found was a reference saying it could have been upgraded to a S-300.
I tried creating the schematic of the board I have, but that quickly became quite a chore.
I did find tracing the initial input seems to agree with the schematic of the S-300, but there are differences too. (or maybe I'm just interpreting it wrong)
Long story short, this amp is a good candidate for the new Stasis FE, which I'll pursue, but I'd like to play with this first.
I'll post some pics.

I've seen some on aliexpress working out to about £50 including spare HEPA filters

https://www.aliexpress.com/item/1005004980225263.html

LUXIANZI Fume Extractor Smoking Instrument With LED Light 220v Activated Carbon filter Sponge Solder iron Smoke Absorber

Here is a DIY Ribbon like speaker from a french guy
François DEMINIERE
His site:
http://home.tele2.fr/mon-site-perso/

Very impressive design with large band of operation.
(250-20000 Hz), SPL 102 dB
Still need a Bass reproducing device to support this
mid high ribbon.
Too bad their is no photos of some prototype!!!

Mandrake5

Has anyone bought one of these PCM56 based boards? https://www.ebay.com/itm/124515637649?hash=item1cfdb5d991:g:woQAAOSwPyxf9TdL

Looks decent with socketed chips and doing mods wouldn't be too difficult.

Signed up to get some help with repairs of some faulty amplifiers.

Hi there!

Yes I'm a new member of diyAudio. As many may also quickly find, English is not my native language, but I'll do my best to express myself in English (that is, not copy/paste my threads/responses from Google Translate!).

I'm a retired Linux SysAdmin with experience with Raspberry Pi for 4-5 years now, mainly to build my NAS solution based on OpenMediaVault and many Docker containers.

Now I'm looking for a solution for my audio players with multiroom. I've tried Volumio first, Hifiberry OS (I have 2 Raspberry that have a Hifiberry DAC), a solution based on myMPD and SnapServer, now trying moOde Audio Player.

As every solutions I've tried have there pros and cons, what I look for with moOde is a solution that will evolve without bumps with every update as I have encountered too often.

Not sure if this is the best area for this thread, but here we go.
My pre-out section on my car stereo recently stopped working. There are three (front, rear, sub)
Rear and sub can be turned off via the software in the menu, but front should be always on. I tested all three to be completely silent. Nothing changed. Everything else works perfectly.
I took it apart for a visual and a few basic probes, but nothing popped out at all.
I am still awaiting a new bench power supply and microscope, so I wasn't able to scope it yet.
Just in case the software got a glitch I did a power drain and factory reset.
Back traced a small bit, there are three opamps then back to a volume control IC, then some traces seem to go back to a dsp chip.
Since Alpine's rep companies in UK won't even acknowledge emails, have no contact number anymore, and Germany didn't answer either, it looks like I'm on my own.
When I do finally get some new tools, I'm gathering ideas on how to proceed. The unit as a whole is pretty complicated and spread between 3 pcb's, but I'm thinking this issue would be contained in this board as the others seem to house the hdmi, usb, and CANBUS interface. The amplifier circuit is working, so I was thinking of tracing both of the paths back to where they meet as, unlike a traditional amplifier, there is no physical input to trace from really. Then taking a signal generator and scope to try and trace it back. I'm still not very adept at following signal path without points a AND b.
Just wondering if you lads had any advice or ideas.
The SMD components go as small as 0402 size and there are many unlabeled larger ones as well which poses an issue. Even the labeled diodes I can't find info on, so it's hard to tell what they should even be reading. At least I can identify the IC's.

Total newbie question, I have never built a speaker. I am planning to build a super tweeter (ST) to sit on top of the bookshelf speakers, a pair of Pioneer SP-BS22-LR . Bunch of questions:

1. I would need a filter to set the frequency, wouldn't I? I am thinking of setting it at 18000hz, make sense?
2. Preferably, the ST will take power from the pioneer's blinding posts.
3. Do the STs have to match the Pioneer's ohm, in this case 6 ohm, and efficiency, 86db?
4. I am planning to have the ST either face the front wall behind the speakers, or at 45deg angle ear and top, make sense?
5. How much additional effort to have a level volume control?
6. What type of driver would be more preferable? bullet? ribbon etc etc? I am open to all.

Thank you guys in advance for helping.

Exactly 11 years and 2250 posts after the original CEN IV, the simple circuit still have many fans and positive feedback.
But the difficulty of having to use floating power supplies remains.
Especially, if one is using 2 channel balanced mode outputs, 4 of these floating supplies are required.

https://www.diyaudio.com/community/...lution-of-a-minimalistic-iv-converter.195483/

The question has been -- is it possible to have at least similar performance but using fixed rails ?
In the original thread, the use of current sources between fixed rail and IV circuit has been discussed.
11 years later, with experience gained from the revised XCEN converter circuit, the puzzle has finally been solved.





So here you are. Happy Reading.


Patrick

.

I am having problems with my Carver M1.5 amp. It acts like the transformer my be bad but I have never had a transformer act like this. With the transformer completely out of the amp,the secondary windings are not hooked to anything and using a Variac on the input widings, I can feed this transformer with 45 volts all day and it will just get warm but push it to 75 volts on the primary and it draws 9 amps on the primary side. At 45 volts in I only get about 75 volts - + on the highest rail. My 1.5T runs 125 volts - + . If this transformer had a shorted winding it would get hot and smoke at any voltage,it does not. It acts like the core saturates at about 50 volts and any more than 50 and you are pushing it hard. Any Ideas?? Many thanks, Al

What should the rail voltage be set at on the M1.5 and 1.5t Carver amps?

Inspired by the Rutcho Dm601 S3 mod, I decided to tackle the crossover on my pair of DM603 S3's using his design. It is my first time diving into this and I will admit I have no idea what I am doing. I imported the response graphs of the Kevlar woofer and tweeter into VituixCAD, and simulated the stock and Rutcho crossovers. I came up with a 1.5ohm R1, a 3.3uF C1, short of the resistor on the tweeter inductor. For the mid-woofer, I created a zobel network just like Rutcho, at 4.7uf cap, but a different resistor value of 4.7ohm.

Using a 2.5 Allen key, I removed the silver woofer. There are three screws - one at the middle and one at each bottom corner. The top corners are held by expansion pins. I used a pair of pliers to squeeze them and put my hand behind the board to apply pressure inward. For the zobel, I cut open and balded the blue and brown driver wires and mounted the capacitor and the resistor from the leads vertically. The mounted components are held by glue, and I had to use a knife to pry them off. I did this to both speakers but my beginner soldering skills had my zobel bridge compromised and open. This gave me a unique opportunity to A/B the before and after while running simultaneous modified tweeters.

The highly crossed Kevlar woofer was essentially distorting at the high frequencies. It sounded like outright white noise and heavily muddied the mid-range.
VituixCAD shows on the stock crossover a terrible phase shift after 7.5Khz and both the directivity graphs and phase patterns looked ugly. My post-mod speakers sound huge, delicate, spacious. it is definitely an improvement all around. However, I lost a lot of mid range and I suspect it is due to the 4.7ohm resistor on the zobel. I could play with 1.8ohms but the second problem is that the phase is nearly completely opposed from 2-4.7 kHz. The vocals sound delicate but they are also distant and lacking bark. I suspect I am not getting the full sound stage yet out of these drivers.

After some research, it occurred to me that the zobel increases the order of the filter. For parity, do I have to do the same to the tweeter? I ran this through VItuixCAD and came up with a 4.3uf C1 (I add a 1uf cap in parallel to the existing one), a 4th order filter created by a 5.6uf cap and a 200uh 15AWG inductor, and reducing the Zobel resistor to 3.3ohms.

Just signed up. Mostly interested in setting up the speaker turn on delay in my pair of bridged hafler amps.
(cant use circuit as is cause I cant make use of the DC protection stuff in the diy board.)
maybe even getting some suggestions on pointers for recapping them too.

Anyone out there got a schem for this ancient little power amp?
Cheers, M

For sale are Jantzen Audio coil inductors:

000-1299 Air Core Coil 2,200mH +/-3% 0,630Ω wire 1,20mm=17AWG OD-57 / 30mm 10€/PCS

000-6542 C-Coil 13,3mH +/-5% 0,25Ω +/-10% 500W / 8Ω wire 1,2mm=17AWG core-40 OD87 H28 32€/PCS

000-8450 Wax Coil 3,300mH +/-2% 0,51Ω +/-5% 14AWG OD106 H37 52€/PCS

Coils are unused

Shipping from Slovenia, EU

Hi, I'm a new member of diyAudio and I'm here to find help and solutions to some of my problems.

Hi I'm new here forgive any mistakes. I want to use two XH-M564 Modules as one amplifier so i can get 200 watt output as 2 channels If possible. Or 4 channels output. This module contains tpa3116 d2 amplifier chip and it is a stereo module gives 50w per channel output

Hey DIYA'ers🙂

I'm almost finished drawing a stereo preamplifier from scratch, only small adjustments is needed before I'll do some gerber files for a PCB order.

Question: does the orientation of the R-core transformer have significant impact?
Would it be better to rotate it 90°

Attached is a picture of the current progress and layout

Best regards

I have a Sony Esprit TA-E901 Esprit pre-amp. It's a bit of a unique beast.

On the phono stage only (all other inputs are fine), I have an intermittent right channel problem in stereo. Especially when warm, the right channel will go dead. Sometimes it will work for days at a time before not working for days at a time. All other inputs will still work perfectly when the phono stage is acting up.

I took it to a known good electronics shop, and they were baffled on what was wrong. They couldn't find anything. They successfully reproduced the right channel issue only on the phono stage.

My question is because the problem wasn't obvious, do you think one of the epoxy modules in the EQ or Flat Amp? Or something that takes more diligence like finding a cold solder or something given the complexity of the unit.

Hey guys new member here. Looking forward to posting some new Unity horn type speakers I've been working on!

My Garmin Nuvi GPS, the one with European maps, isn't taking a charge. While I can use Google or Apple Maps on the iPhone I've found out that you can wind up on a C-Road in France behind some fella's harvesting. Moreover, when we went to Ireland the cell service was spotty and we had to drive until it became operational again.

Garmin no longer makes an automobile version with Euro maps. Even they suggested buying one in Europe.

Lost on how to design a 2.5 way crossover. This is a Vcad simulation using the diffraction tool. Midrange/midbass are 15cm (120mm diaphragm), 1 inch tweeter. What's the trick to setting up 2.5 ways?

Vcad project zip attached

Hi, I have this amp that is blowing the fusible resistor R632 in this Left Channel Amp Circuit. I've tried to isolate different parts of the circuit and have all of the driver transistors Q616, 617, 618, 619. 703, 707 as well as Q609 and all of the complimentary right channel transistors unsoldered and out of circuit and the resistor still blows after some time. When the resistor is out, I measure -70v on one side and like 2v on the other. When I remove right channel's complimentary resistor 682l, I still get -70v but on the other side where on the left I get 2v, on the right I get around 7v. Just looking for some guidance on how to hunt down what's causing this. I have read the variable resistors on this board can cause fits but not sure how to identify if that's the problem here...

Edit Mar 28, 2023: Schematics for Rev 2.3 that have the bonus low capacitance PSU PCB:


Edit Dec 4, 2022: GB5 interest list here - please sign up and 30 units needed for production to commence.
https://www.diyaudio.com/community/threads/rtr-ssr-speaker-protection-gb5.392399/#post-7186273

Edit March 14, 2021: Easy Peasy instant off anti turn off thump mod here:
Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB

Edit Jan 25, 2021: the Gen 2 RTR SSR schematic and notes on use is here. Specifically,
Details on how to connect the power supply and how to use the instant off bonus controller board.

Edit Dec 16, 2020: the GB interest list for the Gen 2 of the RTR SSR has kicked off. They will handle up to 150v or 300w into 8ohms, the speaker negative is isolated from power supply ground to allow use with bridged amps, and there is an external open collector logic pin to instantly shutdown the SSR. $47ea, professionally assembled and fully tested. Free shipping in USA.


GB interest list here:
Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB

Edit Oct. 22, 2019: The full production run has been delivered. They look great!
Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB

Edit Oct. 15, 2019: Here is a photo of the sample unit we tested before we gave the OK for the full production run:


Edit: Oct. 15, 2019: We just received news that all 120 units of the first production run have been completed. Should be shipping them out soon.

Jhofland has developed a superb, simple, compact solid state relay (SSR) DC speakere protection and turn-on delay circuit that is similar to the one used in the ABBB amp. JPS64 did the layout on this, and together, we now have a very nice SSR protection circuit that works "like a wire". It uses very compact SMT parts and the whole board is only 75mm x 35mm per channel. An assortment of connection options are availble ranging from usual spade Fastons to Molex Minifit 4-pin locking jacks, or even plain old soldered flying leads. The circuit uses a topology designed by Jhofland to sense a small DC offset via an opto-coupler isolator and a comparator. The comparator drives another optoisolator to activate back-to-back ultra-low RDson MOSFETs as the SSR. A second comparator provides the 3 second time delay when powering on to avoid turn-on speaker thump. The circuit is powered from the conveniently available +ve DC rail of the amplifier's PSU (range is circa +20v to +100Vdc). The supply voltage is reduced and regulated to a constant value on board via a regulator for consistent performance despite variations in the supply rail voltage.

Initial testing of the SSR DC Protect circuit revealed that when it is on, it truly acts and measures as if it were a piece of high current wire. No noticeable artifacts in the time domain were visible on an O-scope, and FFT's also revealed that it had no effect on the harmonic distortion profile either.

Specifications:

• PCB size is 70mm x 35mm and the M3 screw mounting holes are 62mm x ~26.5mm
• Requires > +19vdc power supply (can use +ve rail from your amp) and internally regulated to 15v
• Fully tested for 100w rms continuous load into 8ohms (MOSFETs are rated for up to 154w into 8ohms)
• Fully tested to handle 48vdc continuous DC fault
• 3 second turn on delay
• For a 48vdc fault, turn-off time is 25 milliseconds, 1.5v thrreshold

The best part of all is that we will be offering this as a proefessionally built and fully-tested, ready-to-run (RTR) unit. The user just has to solder on his/her own choice of spade terminals or Molex Minifit Jr connectors, or flying leads, the +ve supply via a JST connector or flying leads, and then go and use it.

Thanks to Jhofland for the design, and JPS64 for the layout.

3D render of intitial version for testing and verifcation:


Photo of verification build with Faston connectors:


O-scope screenshot of signal at 100wrms into 8ohms with (yellow) and without (blue) - they are indentical and thus perfectly overlaid. Test with Hafler Class AB amp and resistive load:


Edit Aug 7, 2019: New data with VHEX+ amp for 40Vpp into 8ohm load (25wrms) showing harmonic distortion components from H2 through H5 vs Frequency and THD for case without SSR Protection in place:


Same data with SSR Protection in place:


Comparison with overlay of above THD data for both cases:


Comparison of THD vs Power into 8ohm load with and without SSR Protection in place:


Typical FFT without SSR Protection in place at 25wrms into 8ohms:


Typical FFT with the SSR Protection in place at 25wrms into 8ohms:


No added distrotion as shown by test with 40w into 8ohm load with and without RTR SSR using Tomchr's ultra-low distortion Modulus86 amplifier:
Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB


For more technical details of this test, see this post:
Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB

Update August 7, 2019: Pre-orders are now being taken from my shop here. Price for fully built and tested unit is $40ea with Free Shipping in the US; $10 shipping to Canada; $15 shipping to everywhere else.

Update July 29, 2019:
Current interest list shows almost 100 units. Looks like this is a definite go! Latest render with voltage regulator IC and transzorb diode for protection:


With vertical Molex Minifit Jrs:


With Faston spades:


Schematic of pre-production unit:

Hi everybody! I'm a newbie seeking to design my own amplifier. I would be delighted if someone from this hobby could guide me along. Let me try to explain the features and what was intended.

1. I'm designing a stereo amplifier for Headphones/IEMs.
2. I use 1x NE5532 for each channel for a HPF (15Hz - 23kHZ) -> LPF + HPF = HBF
3. I then used 1x LME49720 for each channel for the unity buffer stage + "power" amplification stage.
4. Each op-amp ICs are connected to 100nF & 1uF capacitors for both power rails as decoupling capacitors.
5. I'm using 3.5mm TRS for now, but I'm considering a 4.4 TRRS Balanced connection as well. Maybe both?
6. This is a derivative from the "47-amp", but I'm thinking of making it into a portable amplifier...
7. I understand that L48xx/L49xx voltage regulator ICs is common, but it seem to be far too noisy as the power supply for audio applications and will need further circuit additions to be usable. Is there any recommendations for ICs replacement? With portable in mind, OOTB regulator ICs would be preferred?
8. I intend to do op-amp rolling [the LME49720s] so my first prototype would be DIP8 package for now on a breadboard. If it works, I will move on to PCB design using SOIC chips, the passive components shall be surface mount as well.
9. I will be separating the ground into signal ground (which is use AGND here) and true ground (GND)

Any feedback is welcomed 😀 2 random question out of this project:

1. Does it makes sense to replace the unity-buffer stage with JFET transistor amp design? I heard it makes the amp slightly colored to be more warm... in fact if I could implement both and choose between JFET (Warm) and Op-amp (Sterile) in one circuit would be fantastic!!

2. Am I the only one that thinks the commercial "portable amplifiers" are much larger than needed?

https://www.akm.com/us/en/about-us/news/2024/20241111-ak4497svq/

This thread is for discussion and advice from DAC developers.

The only change in the new IC is the addition of a programmable FIR filter.
Wouldn't this be a fun toy for digital designers?

The AK4497 is a good choice for a mini DAC build, as the current output IC and the peripheral circuitry can be simplified more than the AK4499EX.
I will continue building the AK4497, as I am interested in making thin or compact tabletop devices.

I will receive samples from AKM soon.
The board design is almost finished, as there are no hardware changes.
After considering the VREF supply and the master clock supply, I will move on to the layout phase.
I plan to optimize the 4L layout with the help of experts.
I expect the cost to be around $800-$1000.

I will have all the functions necessary for playback on one board. In summary:
1. 150x100x20mm ultra-slim CNC case, no display design
2. USB I2S bridge (AT32+XC2C64A)
3. LT3471+LT304x based power supply
4. Low distortion Discrete opamp. Don't call it a snake oil
I think measurement and math are the best sound design tools,
and IC op amps like OPA1612, LM4562 are the most convenient products to get the best results
That is, "just for fun" elements. But I will try to get enough THD.

Assume a 6.8 Ohms resistor is placed in midrange crossover at the input terminal side and a 2 Ohms resistor is placed at the same position in the tweeter crossover. The difference between them is 4.8 Ohms (6.8-2 Ohms). If the woofer is replaced with a higher sensitivity one, the mid and tweet will need to lower their attenuations. And if the tweeter is bypassed its 2 Ohms resistor, would it be successful by simply replaced the 6.8 Ohms resistor of the midrange by a 4.8 Ohms resistor? By doing this, the difference between tweeter's and mid’s resistors still remain 4.8 Ohms (4.8-0 Ohms). That means the relationship between these two resistors is linear. Is this assumption true?

This is aimed solely at those owners and potential future owners of first-generation Klipsch Jubilees that want to upgrade them to meet and/or exceed the acoustic performance of second-generation Jubilees (pdf attached).

EDIT (31 July 2024): Those owners of 2nd-Gen (Heritage) Jubilees can also access assistance here in getting those loudspeakers dialed into their listening room environment. There is a real need to do this with virtually all home-sized listening rooms, as the fixed factory settings in the Heritage Jubilee DSP crossover will likely be overwhelmingly imbalanced below 40 Hz. I've also found that "room correction software" packages like Dirac and Audacity have systemic issues in the room transition region (a.k.a., Schroeder transition region) that seems to consistently produce unbalanced results for these type of loudspeakers.

EDIT (27 April 2025): I now have a Xilica XP or XD series processor configuration file, otherwise known as an *.xdat file, that has the necessary PEQ, crossover filters, and channel delay corrections to dial in a stereo pair of Heritage Jubilee with Axi2050 drivers - also known as K-694 drivers.

Send me a message if you have interest in changing your fixed Klipsch DSP box with another third party DSP processor or PC-based DSP solution (e.g., CamillaDSP, etc.). The settings in this configuration file use something known as a "zeroth order" crossover, which has no all-pass phase growth due to the crossover filters themselves. This allows the user to possibly avoid using FIR filtering to further flatten the phase response of Heritage Jubilees.

Chris

Hello,

Had this one in my office for a while. I did a full recapping job, calibrated most of the things, per service manual, then ran into a bias problem and left it there.
6 months after picking it up where I stopped.

What I did:

1. all electrolytic capacitors changed​
2. both Thyristor replaced (were damaged)​
3. Supply voltage adjustment & check done and working
4. Adjustment of load impedance detection circuit done and working
5. DC balance calibrated and working
6. Protection circuit calibrated and working
7. Overload detection circuit calibrated and working
8. replaced output relay
9. cleaned controls and potentiometers

The problem, adjustment of Ico (bias).
The right channel is nicely biased @ 2mV, as the manual suggests. Everything works smoothly with it.
The left channel, oh boy oh boy... Looking at the schematic, my Q317 collector measures 0.5V, Q319 collector measures -3.3V, with respect to 0V. Everything after that is not even close to the values in service manual...
My thought, I have one channel working, and I don't have these transistors in stock, let's change transistors and diodes from one channel to the other and see.
I exchanged (left channel with right channel): Q317, Q319, D305, D307, D311, D309, Q321, Q331, Q333, Q327, Q329. Of course, I didn't replace everything just like that.
I check the bias adjustment after each exchange. The thing is the same... I also checked resistors, all good. I resoldered most of the left channel. Still the same. I measured all ceramic capacitors on the left channel, all good.

The amplifier works, it passed the signal, but after few watts of power, as expected, the left channel waveform (the bottom sine wave) starts to distort.

Any ideas? Any help will be appreciated. Maybe I'm missing something, or everything 😀

Ciao,
John

EDIT: VR301 is also replaced with new trimmer, Z301 power resistor has been replaced also. Schematic is attached, so you don't have to search through manual 😉 The voltages before bias circuit (Q301, Q303, Q309, Q313, Q315, Q311) are correct.

Hi folks, I have a stainless chassis, some Chinese iron, and some Russian and Chinese tubes that I'd like to turn into a decent amplifier. The schematic that comes with these kits varies widely, and the one that came with this kit is a mess. It is attached. It shows the two halves of the 6H8C/6SN7 drivers wired in parallel, which I have been told is generally a bad idea and also not necessary. So my idea is to simplify and just use one half of a single 6H8C/6SN7 driver tube for each channel.

I also got rid of the tube rectification in the power supply discussion here: https://www.diyaudio.com/community/threads/5c4s-replacement-with-solid-state.405726/

I am at the point where I am trying to put together a schematic that will not just work but work well in case I decide to keep this amplifier. It started out as a learning tool and an experiment where I didn't care much about the final result, but now that I am this deep into it, I'd like to do at least a half way decent job.

I have redrawn the schematic to show the solid state power supply and 1/2 6H8C/6SN7 per channel.

• I have no idea how to determine the proper values for the negative feedback resistor and any parallel NFB capacitor. I'd like to move the negative feedback to the 4 ohm output. I will not ever use the 8 ohm outputs, and although I know in theory it should be fine to attach the negative feedback to the 8 ohm output anyway, to satisfy my curiosity I'd like to put it on the 4 ohm output.
• Is there any reason for me to try 4k (or higher) output transformers instead of the 3.5k specified? I'll be replacing the tiny ones that came in my version of this kit and I can get any value needed - update 3/30/2025 - larger replacements arrived today.

So if this group can help me optimize this schematic, at least getting it close enough for me to build it and test voltages and see how it sounds, help would be very much appreciated. I will be replacing all of the resistors and caps that come in the kit with decent parts from Mouser and Digikey. I will get whatever is needed to do it right. update 3/30/2025 - adding parts to Mouser and DigiKey carts. Proposed schematic with regulated screen supply and a single driver tube attached.

I do not have an oscilloscope. I thought about buying one of these but I would have exactly no idea how to use it or how to begin. https://www.amazon.com/Hantek-Digital-Storage-Oscilloscope-Analyzer/dp/B015XVPPJ6

Proposed schematic updated 3/30/2025:

Hi - I have a Quad 33 where the balance is doing strange things. Symptoms;

• With the Balance slide centered - The Right Channel is much brighter in the mid and treble, the left by comparison is dull
• With the Balance slide fully to the Right - The right level increases by about 70%, the left level decreases by about 20%, and remains dull
• With the Balance slide fully to the Left - The the left level increases by about 50-60% and the sound is not dull, the right level decreases by about 10-15%, and sound is dull

I have carried out the tests above with the Controls(Bass, treble & slope) in "Cancel" mode



I have checked RV5. The mechanical linkage is sound, the resistance of the pot is circa 1K Ohms, and in center setting about 500 Ohms either side. This grounding of the center of the pot is good as well.

I have swapped around the M12017 boards, left to right to confirm there is nothing wrong with either of them.

Should I be looking a be looking at potential issues around here?
.

Any help or insight would be appreciated.

Pass' new HPA-1 is certainly getting good press.

Pass Labs HPA-1 headphone amplifier | Stereophile.com

Do we know anything about the design? Push-Pull or single-ended? Based on any currently known topology (Aleph, etc.)?

Just trying to figure out what Pass considers the best approach for headphone amplification.

I've got a bit of an oddball, here.

A disjointed album of photos can be found here: http://imgur.com/a/O95G4

I've been chatting with Craig here (llwhtt) and he's provided me with some documentation to try and help, but I still can't figure out what's going on, here.

I've had this amp for a few years and I'm now finding time to get into restoring it... but I've found a few oddities.

The transistors in the right channel are all Sanken 2SC1116A but the left channel is all Fujitsu (?) 2SC2522. The right channel has C2238 drivers while the left has TIP31C drivers. There are a couple extra diodes on the solder side of the left channel's PCB, and all the quick disconnects are soldered in place. The torroid is unshielded, from what I understand, indicates that this is a later model amp.

Of the three schematics I have, I can't find a single channel that matches anything of what I've got here.

My best guess is that this is a late-model amp, with the left channel being stock, and a repair was done with an old right channel swapped in as a module.

After verifying that replacement output devices are available (unlike The Nine, from what I understand) I tried powering the amp up while measuring the DC bias, no load. I saw -15 VDC in each channel, which slowly increased to -13.7 VDC, and that's when I smelt that burning smell, and turned it off. All the fuses are their suggested value, and all the fuses are intact.

Ultimately I'd like to thoroughly restore this amp, giving it the best I can buy, I just need a few pointers on where to start. I'm fine with stripping this back to bare PCBs and changing out all the output devices should that be what needs doing.

I appreciate any insight and input.


Thanks!
Philip.

The two markings below are T2X. I am unable to identify the other two, but I have encountered T2X alongside T2T.If anyone has information regarding this, I would appreciate assistance, as I cannot locate a schematic for the Infinity Reference 10001A.

The original ZEN Amplifier is simple but great.
But can need a preamp.
Here is where Bride Of ZEN comes in.

I have simulated a circuit which joins Bride with ZEN.
I have reduced gain of the ZEN to x2 and let the voltage gain be done by the Bride.
I reduced the supply of Bride to 40V, so the combo needs only one supply.
THD shows a pretty good figure.

Hi diyaudio community!

I’m acenosekai, a software developer passionate about audio technology and DIY audio gear. I’m especially interested in headphones, DACs, DIY amplifiers, and speakers. I’m here to connect, learn, and share ideas with fellow audio enthusiasts.

Looking for a pair of xds12 woofers

Hi all!

I have had quite a lot of experience with portable speaker design and Bluetooth modules from Qualcomm. I worked with CSR chips, for example, CSR64215 and I didn’t get any problem with programming this chip. Moreover, we have a great thread on this forum with a lot of useful information: CSR8675 programming guide w. software and tons of CSR info

On the market, we have new Qualcomm chips QCCXXXX and the approach of programming not the same with CSR modules. As far as I know, the last chip that supports CSR programming process is QCC3008.
And new chips have features:

• APTX-HD, APTX-Adaptive (QCC5125)
• DSP Kalimba, a key feature for me.
• Bluetooth 5.1
• Ready-made modules with amplifiers and external DACs

These chips have DSP Kalimba and that gives the opportunity to set up audio how I want, make limiter, EQ, bass booster, etc.

I know that this DSP not so powerful as, for example, ADAU1701, but that makes my project chipper using only one chip for wireless connection, DAC and DSP.

QCC5125 and QCC3034\QCC3031 have the same programming approach. For programming those modules, we have two ways. First, we need special programming expensive board. Second, programming with USB.

I found ADK for QCC3031 on the thread that I write above, thanks a lot @ErikDIY for that. I tried to connect this chip to a USB, but I didn’t get any success.

I have this module - BTM331.




I would like to ask you to share your experience, how connect this chip to USB? How configure DSP Kalimba on this chip by USB?


On USB we have 4 pins

• GND,
• Data+
• Data-
• +5V

And we have pins on QCC3031(BTM331):

• VBAT_SENSE
• USB_DN
• USB_DP
• VCHG
• VCHG_SENSE
• CHG_EXT

Which pins from qcc3031 I need to connect to USB pins?
As I understood Data+ and Data- from USB need to connect to USB_DN, USB_DP from QCC3031.