Regards,

Some "leftover" audio boards found. LME49710HA/ LME49600. Preamp or Headphone amp. New, tested. Gain setting by changing resistor on gold plated sockets.

Price 35€, shipping ( registered with tracking..) 5€ for EU, 7€ other countries.

Regards, Davorin

I just came into possession of a Dual 701 in beautiful shape. I'm trying to identify the cartridge, but it looks like the plate with the model name has fallen off.

It is definitely an Ortofon, probably an MC. The seller said that an STM-72 was connected to the turntable when they got it, so it's probably super low output.

Best I can tell it's an MC MkII, but I can't find anything to confirm the specific model. That would be an all black cartridge with the same shape, and the model name printed on a plate in that square. It looks just like the one on Ortofon's website, but all black with a missing nameplate.

https://www.ortofon.com/mc-series-p-704-n-4873

hello everyone
Recently, I need to make a micro power consumption high voltage low current (<1mA) boost power supply.
Is there any simple circuit for boosting 30V to 60-70V

Hello,

I was recently researching the idea of removing my tone controls (or bypassing them) and came across this thread. In it, a member mentions 2 possibilities: 1) the tone circuit is passive, therefore replacing it with a resistor of equal value will suffice. Or, 2) Tone controls are configured as feedback networks.

I have limited knowledge in interpreting schematics, but a working knowledge in performing the repairs/mods if I clearly understand what needs to be done. If I include schematics, would any user be kind enough to tell me if my tone circuits are passive? Or if I have to research the feedback network concept a bit more before proceeding.

I'd greatly appreciate it!

Hi everyone!

I would be so glad if a kind owner of these loudspeakers told me how the position of the notch of the L-Pad knob appears at its clockwise end-stop since I lost the default reference.

Thank you very much in advance.

Hi!

First post here,
I'm working on an embedded project, where I need to adapt a 3 wire microphone with a 2 wire headset.






I need to use this electret microphone, and his tiny board (I cannot remove it, that's the challenge of this project) , with this receiver:


(Don't pay attention to the measurement)

I tried to power the tiny board with 3.3v but the SIG wire returns a pchhh and, I need to scream to have something more.

I really appreciate any help!

Hi,

I need to make a portable, powered, mono speaker.
Power source will be a 5v power bank. Need a compact, 15-50w output amp module that works from 5v supply. Anything out there? Ideas?

Thanks!

Hey all! Apologies if this isn't the correct area for this!

I recently picked up a vintage Luxman integrated amp for super cheap in hopes of doing some DIY repairs to it! Upon further inspection, the left channel seems to not be working whatsoever.

I believe whatever this black gunk is, is likely the culprit... (Apologies for the pics being kinda bad) It seems like the source of the gunk is near the left channel board, which isn't surprising.

Does this gunk look like it came from a burst cap? Or could it be something worse? I haven't been able to take it apart yet sadly.

Also, from the third pic, are these ceramic caps about to go? Can't say I've ever seen those bulge before....

Thanks for any insight!

hi!
I am looking for a replacement loudness switch because the old one is probably worn out and makes both channels play unevenly when pressed. Does anyone know where I could buy one?

I have read on the website of German's distributor TAD, that this model is out of production - go to
Fane AXA Studio 12L 12" 200W 8 Ohm - Axiom Tube Amp Doctor Onlineshop
BTW - this isn't mentioned on the website from Fane Acoustics - go to
Fane International Ltd Loud Speakers
Who know the successor?
Thanks for advices.

I finally took the plunge and picked up a carver pm 1.5 on ebay for cheap which got delivered today and it sounds awesome with my magnepans-better than the class a 100w monoblocks I was using but it has a small crackle in quiet passages but only does it when music is playing no sound when on standby. What are the first things I should check-clean etc? I have never owned one so I'm not sure what to look for

Been using Internet Archives for some downloads. Alot are just short samples. Looking to burn CDs so mp3 is fine. Know how to burn to CD with old laptop but most services are not free. Any suggestions. Not interested in anything new just old stuff .. Thanks for any suggestions. Michael

Looking for a prebuilt Boominator or worst case scenerio provide a complete build kit. I would also be potentially interested in any outdoor portable builds that have a power and bass similar to that of a Boominator. Located in the US

This is an older mod I did to a Yamaha CA-810 to stop its preamp from picking up FM radio. Finally got around to posting it for someone who asked for the schematic.

I live a half-mile from a strong FM transmitter. Here, a fair fraction of vintage preamps will pick it right up -- it bleeds through audibly into the output. This was one.

Usually, increasing stability margins of the gain stages will fix it. I'm fond of using two-pole compensation for this: generally you can lower the unity loopgain frequency, and obtain much more generous stability margins, without sacrificing any in-band feedback or changing the sound of a preamp. A ULGF below 10MHz generally means the circuit simply cannot operate at 100MHz, not actively.

These are the mods for the CA-810:

• Delete C311
• Replace C321 with 4p
• Replace C323 with a 1.5k / 100p / 100p TPC network as shown in the schematic. This is C2, C6, and R1 on the schematic.
• Replace R325 with 470 ohms. (This may not be strictly needed to improve stability, but it lifts TR305 out of quasi-saturation, which makes me trust spice to better model this circuit and surely helps with distortion performance.)
• For the 2nd gain stage after the tone controls, add a 1.5k / 82p / 82p TPC network from the collector to the base of TR313. This is C5, C7, and R3 on the schematic. This transistor had no miller cap before, but it benefits from some compensation from collector to base.

Resulting schematic attached; original schematic is available on hifiengine.

I'm a bit confused right now, so please give a simple explanation 🙂 A waveguide is always connected to a tweeter and with a compression driver the tweeter is always connected to a horn. What is the difference ? or are there variants where the waveguide is not directly connected to a driver?

So I just got in a Memphis amp, the 16-MCD500, blown power supply, negative terminal got so hot it melted off the board, removed damaged FETs, resoldered terminal back in place, confined I had power supply switching, installed FETs but amp doesn’t power on just clicks, I pull rectifiers, still just clicks when applying remote, I check resistances (which I should have done before installed FETs) and the 1st 3 have a resistance e of 3.6k between gate and source, the next 3 have a res of 39k with probes one way, and 46k with probes reversed on gatw and source of Fet. I tried looking for the pull down resistor but can’t locate it, what would do that? That has to be the problem correct? I’m still learning but I know that’s off. Any help greatly appreciate. Ty!

I have been using my stock Dell computer soundcard to make analog tape recordings from digital sources such as Quobuz, and I want to upgrade the interface. I read somewhere that an external soundcard will be better because it uses the USB buss rather than the internal's use of the "PCIe expansion buss". Is there any truth to this? What's the best way to convert the Quobuz files to analog?

Hi all,

I was given these a few years ago for a potential project but it never worked out. I believe one is an HPD and one is a Gold.

If they are of interest to you please get in touch with an offer. Bare in mind these are super heavy. Measurements taken today.

Heavily pregnant and not to be disobeyed wife forces sale.





---

I found a transformer rated 24v-0-24v 600w max for a good price

Can this be used with IRS2092 board like this?
350W IRS2092 + IRFB23N20D Class D Power Amplifier Board (Dual Rectifier)

Or something from the LD15 or similar?

What power output could I expect into 4R? 1 board vs 2 boards?

Capacitors for this transformer?

Thanks and regards
Randy

For sale is a brand new ADAU1467 DSP board.

Bought for a project, but never found the time to use it
Comes with Zip file containing example files and schematics and cables (power and toslink)

New price at aliexpress is 140€. Asking price is 110€.

Shipping is possible. To be discussed in PM.

.

Hello, I just joined and would like some advice on my rather poor situation with my speakers.

So basically I have two cabinets with dual 10" cetec gauss 3161DSX drivers in them. These are about 30 years old I think, at least 20. The problem is that I got them from my school, and as such they are not pristine in condition. In fact they are far from it. The drivers are suppose to be 16 ohms each, they aren't anymore. In one cabinet one speaker is 13 ohms and the other is 11.8. In the other cabinet one speaker is 12.1 ohms and has a hole the size of a screw driver tip in it and the other is dead (I think the wiring broke internally).

My question is, should I have these repaired? Cetec gauss repairs are costly because no one makes parts anymore and I don't have money for it anyway. My other option would be to buy some drivers and build some small 3 way monitors for myself. I was thinking of some 8 inch daytons for woofers and some older but in great condition 4.5 inch aiwa full range speakers for the mids and for a tweeter I just don't quite know right now. I am going for an accurate sound reproduction for acoustic guitar and some other music like metallica.

Please any advice is helpfull. My limit in spending is 300$ for both speakers. Thanks

Hello,
This is my first post. I have question about maximum voltage (B+)for Tango XE-20S. I'm interested in 813 single ended. But, I'm not sure, I can used XE-20S for 813SE OPT. I need to run 700-900V for B+.

PS. I'm sorry about my english language is poor.

For sale:

NOS OPA627AP '97/'98 date codes Qty 3 for $55US

NOS Cutler-Hammer; 2-pole rotary switches; from 2 to 25 positions (with all stops removed (continuous rotation) - per pole; Make-Before-Break action; Really nice wipe. $20US EACH. Dimensione - Approx 1.5" on each side. 1/4" shaft diameter - 1" long. Switch mounts with two 6/32 screws thru front panel

Postage EXTRA

Thought some people here would enjoy this video. It's a great explanation of BJT transistor theory from Electroboom. Login to view embedded media

my amplifier sound kit is not working yet ic4558 is not proper work it is dual supply kit 4558ic oin no4 n 8 showing11volt but others pin not showing vltage please guide and help full reply thanks

I’m planning my first PP build and the ST-70 topology is of interest.

It didn’t take me long to realize the main issue with this one is the scarce/expensive 7199 input/driver tube. Which some have swapped with things like 6GH8s and similar. I’ve seen some kits, articles, posts about using other tubes but can’t really figure out which one would be the best.

So as of right now in 2022, i’m wondering if there is a “generally accepted” alternative driver section for the ST-70 which uses separate triode and pentode tubes or just triodes?

$90 shipped
$60 local pick up
Heathkit C-3 Capacitor Condenser Checker Resistor Bridge Green Eye Tube

I posted a few plots of this speaker build on another thread of xrk971's, so thought I'd stop hijacking his thread (http://www.diyaudio.com/forums/multi-way/285030-bookshelf-multi-way-point-source-horn-post4734171.html) and start a new one.

_______________________________________
Edit Dec 18, 2016:
Since this thread is long and meanders a bit (or a lot -- including extended debugging times), here are links to full plan sets, final crossover design, polar and distortion measurements:

• Synergizing the SEOS15 waveguide: http://www.diyaudio.com/forums/multi-way/292379-small-syns-10.html#post4788726
• Sealed Box plans: http://www.diyaudio.com/forums/multi-way/292379-small-syns-19.html#post4843715, and http://libinst.com/SynergyDIY/SmallSyns/SealedV2/Sealed%20Box%20Drawings.pdf
• Ported Box (deep version) plans: http://libinst.com/SynergyDIY/SmallSyns/ShelfPorted/SmallSyns%20Shelf%20Ported%20(deep)%20Drawings.pdf
• Crossover design and (ported version) measured response:Small Syns
• Horizontal Radiation (off-axis) patterns: http://www.diyaudio.com/forums/multi-way/292379-small-syns-8.html#post4787283
  
  
  
  
  
  
  
  
  1/6th octave curves, 5 degree increments, outdoors, no windowing
• Vertical Radiation (off-axis) patterns and color polars H&V: http://www.diyaudio.com/forums/multi-way/292379-small-syns-post4787289.html
• Distortion (sealed version) at usably loud levels: http://www.diyaudio.com/forums/multi-way/292379-small-syns-8.html#post4787300

When the weather lets me out to work with the saw again, I'll be building a shallow version of the Shelf Ported Small Syns. A 29" tall, 20" wide and only 9" deep box for mounting near the wall with minimal room intrusion.
_______________________________________

This one is about a project to use a SEOS15 in a partial Unity/Synergy arrangement, with a midrange driver bandpassed into it and woofers ported just outside and below the waveguide through a pair of slots. The idea is to extend the horizontal directivity a little lower with the array effect of the woofers, while keeping their output locations close enough to the center of the waveguide to keep vertical polar behavior (relatively) well behaved - an essentially point-source behaviour with directivity. I posted some plots of an earlier attempt of it using a small Celestion CD for the tweeter, but it had some distortion issues trying to go too low in frequency. So starting here will be the version using the new Peerless DFM-2535R00-08 driver (which, contrary to angst and gnashing of teeth comments within this thread, is NOT discontinued, and is in fact available from Parts Express at a very reasonable price!).

Here's some pics of the cabinets to show what it looks like.









What I'm going for is:

• smaller size than most Unity/Synergy variant speakers
• better WAF (a non-flashy understated cabinet, works well in any room)
• designed to work close to wall behind it
• Easy to build without exotic tools (buzz saw and jigsaw, and drill mostly)
• Good polar behavior, particularly in the horizontal
• Good sensitivity >93dBSPL 2.83V/1m
• Tolerable impedance (4 ohm nominal, try to stay above 3 ohms min) (ended up with a dip to about 2.9 ohms)
• Relatively simple crossover (got less simple, but still not bad)
• A sealed version (will need subs for any real bass) and a ported full-response version for full-range

I'm NOT going for linear phase for these designs, as I think it is much more practical to linearise phase after-the-fact with a FIR equalizer if that quality is judged to be important (I'm not entirely sold on it after some tests -- polar pattern, single point source, and response shape seem to be a lot more important, from what I've been able to hear in different speaker designs).

The trick to this design is to blend between the midrange and the woofer pair to get reasonably flat, but dropping in level, off-axis mid-high response. It's not very easy to get! I've been simming this in XSim using separate driver objects for each driver type at each angle, connecting the matching types to balance the off-axis response by trial and error.. It takes a fair amount of time to work into something reasonable, but build results do tend to match the simulations quite well.

Harmonic distortion in the tweeter range is pretty good now with the Peerless tweeter and a little more agressive crossover slope



Another midrange could be added on the other side of the waveguide, but I think this is ok without it and minimizes diffraction within the waveguide for the tweeter.

When I get things more complete, I'll put up some build details, including how to modify the SEOS15 waveguide for synergy operation, in case anyone wants to duplicate the design or use it as a starting point for further developments. Please stay tuned!

edit Feb 22 2017:
Next (shelf ported) version --



I hope to get started on this in a month or two

Dear all,

I'm interested how can such a PA-class 8x100W (RMS)@8R amplifier be specified to 2400VA power at the device's back panel at the AC inlet (this isn't the issue) when it's transformer is rather small. Compared to my own, several types of toroidal transformers, this transformer should not be rated for more than somewhere between 200-500VA or so .. ?
But if I look at the specs, something's wrong.

What do I miss here ?

Assumptions:
1. Is this amp about a "classic" - typical overrated kind of animal, where specs are nowhere near reality ? (But in the PA world I wouldn't expect that, there specs need to be delivered, period).

2. Or is it overloading the small toroidal transformer and at the same time let it run hot (because of active cooling) ? Even in such a case, 100˚C would already be too much for such and I still doubt this trafo is enough for feeding all these 8 channels with this size, keeping up with the specs.

3. Or is it a switching PSU which by design can be built for huge powers with relatively small transformers compared to linear PSU-s ? (But then, the current must be huge, running through the transformer).

So what's the big magic here ?
Specs here and 2 photos for understanding my question and worries.

The situation is: one such fully functional transformer is for sale in a DIY group, built out from such an amplifier (no typos) and we simply all wonder how the hell can a transformer of this size (estimated to 250-300VA) feed the device it was built in. The full specs are missing but anyway, this is it. It's either a big-current, enormously strong transformer in an unbelievably small size, or it's part of a switching PSU where they're inherently smaller than their same spec'd linear PSU brothers.

Dimensions: Diameter ⌀13cm, height 11cm, not a big one.
What might be the trick and last but not least, what might be the specs of this transformer ?
1 primary - 230V
2 secondaries - one (80V with center tap?) and one 22V.

Thank you & see attachments.

I had a spectacular failure of an EL34. It was absolutely incandescent orange and as bright as a Roman candle. I didn’t know whether to run toward the amp to switch the damn thing off or jump behind the sofa!

This is a PP, UL design. I found the screen grid stopper resistor was open and burnt. It looks like a KOA Speer SPR 3 watt 100R, one of those light green carbon film ones with the color band markings. In order to get the amp running again I pieced in a couple 47Rs I had on hand in series, again carbon film. That together with a fresh tube took care of the problem. I’m probably fortunate the output transformer was spared. I’m using some Winged Cs that test well and sound great yet are long in the tooth; I’d happily replace them if not for the current situation with tube supply.

So I’m thinking about the specification of those resistors. Is 3 watts really the correct value? Is carbon film the best choice from a fire safety standpoint? I’ll note that they performed well, failing open with just minimal signs of charing and the KOA Speer data sheet describes them as coated with a flame proof silicone coating. That not withstanding, would I be better served with a metal film or wire wound resistor? And perhaps a 2 watt resistor would have fused more quickly thus saving the output transformer some stress?

Any coaching on best practices here would be appreciated.

I have these old Audioengine A5 powered speakers, sitting about 3 meters away.

These use built-in TDA7294 amps with passive crossover onto 5" woofers + 1" dome tweeters, approx 8L boxes.

I don't have an SPL meter, but at moderate volumes, they basically sound fine, but when I increase the volume to "loud" (not insane loud, mind), they start to sound unpleasant - voices become very shouty is the best way I can put it, and treble becomes nails on chalkboard-like. One quickly wants to back off the volume at this point.

Technically, why is this?

Hi all

Since yesterday, a new milestone is set in the history of spice models.

I'm proud to introduce the world's first usable spice model for reverb tanks! 😀

After a bunch of impulse signal delay time measurements with a function generator and a scope on a sample of a TAD 8FB2 reverb tank, I was able to mimic the reverbs behaviour surprisingly well with spice's transmissionlines. The degree of reflection is managed by impedance steps from one transmissionline to the next or to a termination resistance.
Also the complexe impedance of the input and output coils is modeled, considering Rdc, inductance and parasitic capacitance.

After some experimental trials, I'm now able to push a 5s guitar track through my virtual reverb tank, and mix it with the original signal in half a minute of number crunching (with a Intel i7 2.9GHz CPU). Well, that's not super fast, but acceptable in my opinion.

However, if you are interested in the model or want to listen how the result sounds like, just visit my page:
http://adrianimmler.simplesite.com/448517750

Any feedback/proposal is welcome!

all the best, Adrian

Hello everyone,

Does anyone know what internal wiring does altec use on the model 19 or valencias?

Been looking for information but o couldn’t find any.

Thanks

I'm very familiar with Threshold products (still have a FET 11g (German FET 10HL e series) and a Stasis 3 on Infinity's Kappa 9A's (Yes the LED's go all the way up when thundering along when my wife likes to dance to a beat, no kiddin'). In the past I've had a S/300 Series II, two S/500's, S1000 series II and SA1/'s optical bias.
The S/1000 was a bridged S/500 and the SA/1 a massive parallel S/500 throttled back to a railvoltage that allowed 160 Watts Class A at 8 Ohms.
The Pass X1000 is a bridged amp also like the X600 and X600.5 which are bridged X350/350.5s.
The XA160 is a single ended massive parallel X350 (probably the best sounding of the four?) and the X160.5 is a pushpull massive parallel X350.
Please correct me when my assumptions are wrong.

I've read a Stereophile review of the XA160 (1 nov 2003, https://www.stereophile.com/solidpoweramps/1103pass/index.html) and although very favorable soundwise the measurements weren't that great especially in the current department. If you have a hornloudspeaker there's no problem, but anything with a low efficiency combined with a tough load makes these amps unhappy I think. I have such a speaker an Infinity QLS.
In that case would a X600.5 my best choice and what is exactly the difference between the X600 I operate now and the X600.5?

Thanks

Hi, I've been reading the forum, and recently made my first pair of single driver small tower based on Faital Pro 3FE200 which resulted quite good so now I bought another pair, also 8FE200 woofers and a pair of "American Vox" Tweeters rated at 95db. There are not many options in my country.
The design is a 40L vented Box with a look similar to JBL L100 or those old school speakers

Could you please tell me if this 1st order crossover is a good starting point. I like the simplicity of it and the reduced phase problems, but I have two concerns:
1)Will this be too bassy? I'm thinking of reducing the Mids low response by making a small mid's enclosure and also I'm considering there will be a baffle boost in the mid frecuencies. I wont mind a slighly V shaped sound with this project.

2) In the 2-3K region the 3 speakers will be contributing almost equally, is this a problem?

Some notes:
I could also low pass the Mid, to reduce the low mids, but first i'll try to reduce them acoustically with the enclosure.
Tweeter response is not the actual response, I found a similar driver and using that response, here it's inverted to work properly.
The mid range driver is the least sensitive one with 91db, vs 95db woofer and tweeter.

Thank you in advance! This is my first post, if there is any problem please let me know.
Regards

Dear friends:

Here is a new thread.

Purpose: revision of the existing thread
http://www.diyaudio.com/forums/solid-state/174468-very-best-amplifier-i-have-ever-heard.html

I will ask this with total kindness:

The mentioned thread was very confusing for many members like me. Of course it is full of good knowledge and wise people. But many members are fond of selfishness and some others have been mocking arround.

Please be so kind to contribute with an open mind, avoiding mysteries and sharing knowledge, with a real hobbyst point of view. That's is what a forum stands for: help each other and share good information.

Lastly, please upload schematic diagrams and try to clearly explain what you think and/or suggest.

I bought 2 original boards that work with just 4 MOSFET transistors as power output (not 3). I suggest to start with this first schematic and try to stick to this.

I suggest to order this first part and then we could jump to many other ideas and circuit revisions. But I kindly ask not to fall in the other's forum disorder .

I am uploading the original schematics and board drawings as NagysAudio provided.

Any suggestion is very welcome 🙂
Roberto

Comes with box, and all media.

$50 plus ship.

Thanks

Hi
I would like sell Allo DIGI spdif transport with metal case (without rasp pi)
Price $35 with shipping

myint67

In order not to pollute the earlier "open source" lm3886 thread, here's a thread for the successor board, trying to benefit of the lessons learned along the way.

The new PCB has been rethought to be easier to integrate, with a bit less wiring too (the intended use for this redesign is integration into an active speaker). Which means:

- Its size is 4.75cm*10cm. This allows it to fit on a common 50*50mm, 2mm thick aluminum corner (if needed, cut to 50*40). If one picks 25*30mm caps (which go up to 6800uF/50V at mouser), the total height can be: 2mm (bracket) + 5 mm (diode bridge) + 1.6mm (pcb) + 30mm (cap)= 38.6mm.
- The PS is fully onboard, including the diode bridge, meant to go under the pcb and be heatsinked by the aluminum bracket. Main caps are 25mm wide. If height isn't an issue, you can find up to 10.000uF/50V caps in that diameter.
- There is no DC protection onboard as it isn't really necessary in most cases but there's an header to power an external board if so desired (see the open source thread).
-Ground loops are managed through both the possibility to use a 10R resistor between signal and power ground and the possibility to use a CL60 NTC between the power ground and chassis ground.
- Power inputs/outputs can be screw terminals or spades (vertical or angled connectors).

Obviously, all "optional" components are onboard (this is a completely standard datasheet implementation) and attention has been paid to the advices received in the past (thanks again to Tomchr, Mark Whitney, DPH, Bozoc, among others).

Comments, suggestions for improvement ?

Peerless 10" PR would work
Seas 10" PR would also work

I will tune the speakers low, 20Hz or so.

Thanks for looking

I am interested in what you would recommend for small experiments, prototyping of ideas, and maybe just some tools in learning the basics of amplification using vacuum tubes. I know people actually still use real wood boards as the bread board. The Global Specialties PB series of breadboards are rated at 36V/1.5A max , so I guess would be suitable for 24V ideas. I would really like to know your favorite method or any ideas as it applies to my intended use, stated above.
Thanks for any help!

Alan

I just bought this little 12 watt Ace Tone Elite. It needs a bit of work, so I thought I'd hop on here and see if I could get some questions answered.

First of all, the pictures are here and here.

- The first thing I need to do, of course, is replace the 2-prong cord with a 3-prong cord. So my question is, how do I safely get to the underside of the power board so that I can drain the filter cap? Or can I do it without getting underneath it? Should I just screw the ground from the 3-prong directly into the power board?

- I replaced the 12AX7 (far right) but I also need to replace the other two tubes as well (the one on the left is a 6GW8 [triode + pentode] and the middle one is a 6AV6 [duplex diode + triode]).

- I'm assuming I need to replace the filter cap (just based on apparent age). Do I? Do I need to replace any of the other caps?

The amp sounds pretty good, but the tremolo and reverb aren't currently working. I had hoped that they were running off of the 12AX7 and that replacing that would have fixed it, but that didn't work. I suppose the triodes on the other two tubes could be for the tremolo and reverb, but I would think if the triode in the 6GW8 was out, then the pentode would be dead too), so I'm guessing something else is to blame for the tremolo and reverb being out. If anyone has ideas on that, I'd be interested in hearing them.

Once I get the power board off I'll pull the other board and draw the schematic for it and I'll post it here, as I have been unable to find a schematic for the Elite and I'm dying to know how it's put together.

Finally, it has no standby switch. Should I add one?

Any other recommendations? So excited about my first tube amp and glad to have it be one with a little character.

BTW, at $90, how'd I do?

Just cover the shipping, looking for a good home to finish them up.

ALL GONE

Hi,
does anyone know the old program for the acoustic load of the woofers which was called boxdraw v.2.1?
I remember it was very interesting, thanks.

Hey,
Saw these on Audiogon and wondered what cabinet would best suit them? And what about using them full range?
Look to be in great shape

Hi,

I have a Meanwell LRS-200 48V power supply that I bought by mistake. I've no way to send it back for a refund or replace it with another.

Just don't want it to toss it in the bin, so I need to buy a buck converter to use it with a CLASS D amp I own, the WONDOW JAB5. This amp works with 24V-36V, so I need a good buck converter.

I've seen ton of them in Aliexpress, but IDK if they are reliable or not. So, my question is:
-. Would you recommend any seller in Aliexpress that provides a good buck converter?
-. If not in Aliexpress, maybe in another marketplace?
-. Any spec I should keep an eye on, for a good performance?

Thanks in advance.

Cheers.

I am in the process of a project creating a 4 channel chipamp with active crossover to drive my B&W 685s. So first step was to strip down the speaker and see what it is made of. The bass-mid driver seems reassuringly heavy. The tweeter has a sort of tube on the back - I don't know what that is all about but seems to be well-regarded. The existing crossover is surprising. One capacitor in series with the tweeter and one inductor in series with the bass-mid. Both high quality components so no arguments there, and I know there is a school of thought that says the simpler the better, but a first order filter on both drivers doesn't seems promising in terms of phase/coherence. So it will be interesting to hear what these being driving by a 4th order linkwitz-riley sound like (and if I can tell any difference!). Pictures of existing crossover and components just for fun. I am reusing the boards and replacincg the inductor with a short and the capacitor with back to back 2200muF electrolytics (as DC protection for the the tweeter).

I got this amp in for repair .

The owner stated that the amp makes the subwoofer flutter he said the amp doesn’t do it all the time more like 80% of the time is does this then the other 20% the amp works perfectly fine .

He said that there are 4 other amps in the system and they all work perfectly fine .

So I’m assuming this is not a broken rca ground inside the head unit .

Any ideas on what to check in this amp since everything I’ve checked so far appears normal

I just bought a pre-made XO board and I can't work out what the values represent and why they were chosen.
I bought it for the cheap inductors, posted cost was less than half the cost of a new 6.8 cored coil
It's an old Jaycar CX-2630 and it is "Supposed" to be for 100Hz.
I've lost my text books temporarily and I need the formula for reactance.
The values are a 6.8mH coil and a 180uF cap to the woofer and the same value cap in series to the other speakers.
A stereo crossover but mounted on one board and similar to some I've found in old passive subs from RadioShack that used dual VC drivers

Also is there an easy or good way to cut one of these boards in half if I decide to use it as-is.
Appreciate any advice and help and thanx given in advance

https://www.ebay.com/itm/321393003587

can anyone tell me if this is a good choice as any for wire? or is there a known source i can get wire drum from for inductors?

Hello,
I’m new here and looking for help understanding the difference in Lm3886 chips as I cannot find a direct replacement for the one that let the smoke out on my studio subwoofer (the elusive Event 20/20 s250). There are 4x chips, one is burnt out. It reads PM96AT LM3886TF, photo attached. I can not find its exact replacement online. Any suggestions on a replacement? Several listing for the JM64RE LM3886TF, will it work the same? Any help is appreciated.

I just got a classy looking amp from a friend. It obviously has two blown transistors because the resistors next to them are all burnt out. Anyway, the label on the chassis reads

No. 18300
67095
MODEL DPA150-2

if anyone can identify this amp, please let me know. I would like to get the schematics for it so i can fix it. (It’s hard to read the numbers on the transistors...)

Hello friends, this is the story.

A good friend enjoyed this amplifier for about 10 years until one channel exploded. This also killed one of his favorite and expensive speakers. He asked me to take a look at it and try to fix it.

It has 2 identical small PCB's, one still works, the other can't be fixed because it caught fire. Literally. You may like to see the uploaded pictures.

I made some research and could disassembly the dead channel PCB, and could entirely personally redraw the PCB and have it manufactured. The entire schematic could be deduced from the bare PCB. All parts measured. I am also uploading the schematic. The LTSpice working simulation file is also provided. I could recognize this circuit as some Goldmund variant, probably model 330. I tried making some of these variants from information gathered from this same site and I could make them work almost with no problem. The circuits I used were simpler, with Semelabs BUZ900/905 MOSFETS, and a simpler driver stage.

You can clearly see the different color of the PCB soldering mask. Lighter green for the old original amplifier, and darker green for my new, copied PCB. I bought all the parts from Mouser except for the lateral MOSFET's that I replaced for Exicon parts, obtained from Profusion, GB.

The problem: being the new PCB's identical to the originals, and being the original working board fairly stable and well behaved, the new replacement boards (I made 2 of them) is making me nuts 😱. The working voltage is +/- 60V and when my variac reaches the point for +/- 40V, I get a strong 22 MHz sine oscillation at the speaker output (no load), input shorted.

All kind of solutions I tried with no reasonable results at all. The only difference are the output MOSFETS. EXC10N20 and ECX10P20 in place of the originals Hitachi famous 2SK1058 / 2SJ162.

Ferrite bead on the gate terminal of each MOSFET, larger stopper gate resistors, small Zobel network placed across drain to gate of each MOSFET, compensation capacitors at previous VAS stage, heat sink connected to ground, etcetera.

Some strange things I detected by testing the original working amplifier.
In some way I think I could understand the reason, later on.

The working amplifier does not show quiescent current of the output MOSFET's. The offset balance trimpot does not show any kind of output DC change at the output when adjusted. The attached schematic shows this trimpot as R3 and R4. The output DC voltage with input shorted is about 2 mV or less. When applying input signal to this working amp, it shows no visible distortion, and delivers full 55 Vp-p sine wave from 5 to 50 KHz flat.

BTW, very hot Q1 and Q5 ! ... being small signal transistors TO-92. I believe that this could be the reason for no quiescent current at the output devices. I tried to raise Iq a little for a short time by changing R7 value from 330 to 430 Ohms. This should increase quiescent current to 130 mA per output device, that MOSFET's usually like. It worked, but Q1 and Q5 suffered. I returned to the original 330 Ohms value. But this amplifier and his twin worked for 10 years almost all day long, with excellent sound quality.

In the other hand, I don't know what else to do with my copy version. The Exicon MOSFET'S were ordered as matched units, 18 of each type N and P.

The only thing that make the oscillation stop was to place 2 x 100pF C3 and C4 capacitors, which I think is a huge value. The oscillation stopped but the output devices quickly raised their temperature, I don't understand why ! I thought I had solved the problem. 😕

Also, I lowered the feedback resistor R22 to 3K75 half its original value. No changes.😡 returned to riginal 7K5 Ohms value.

Please, could somebody help me think what can be done to make this amp work ? I would thank this help very much.

Finally: today I ordered 20 units 2SK1058/2SJ162 from Pacific Semiconductor in Canada, to avoid any fakes from other source. I have not too much hope because these are not matched units and these are too few pieces to get at least 2 matched pairs...

Thank you in advance !

Using the anotated schematic I attach. I have this PSU with bridge B3 populated. If I feed AC into AC1' and AC2, no CT connected, and take a single rail positive supply out using v+ as pos and V- as zero.....is this acceptable? Have tried it on the bench and it 'works' but I'm not certain it is the done thing. To my mind the caps aren't doing anything as they have no reference.

Hi all,

I'm new about the place and I'm really looking for a bit of guidance.

I'm a woodworker with experience making small boxes so I think I can do a reasonable job of a pair of speakers. I'm interested in experimenting with MDF and laminating, though I'm far more familiar with solid timber. I suspect my final design will be a combination of the two, possibly with some heavy plywood bracing. I've seen some fantastic projects by a lot of DIYers and I'd like to build a pair of powered (Lepai LP40PA amplifier) bookshelf speakers for my sister who's had a difficult year.

A couple of projects have piqued my interest, notably the Parts Express C-Sharp and another pair of slightly bigger, front-ported speakers I've seen someone build on YouTube. I'm not interested in purchasing the full C-Sharp kit and would much prefer to build the enclosures off a plan, rather than from pre-cut parts. I have access to an excellent professional workshop.

I have a couple of caveats. First, I'd prefer a slotted front port and I'd like something in the 150mm/6" driver range (but no bigger) and I'd rather not go below 125mm/5". I have thought about full range drivers but it seems to me the best results with those are in transmission line enclosures. While I have little doubt I could build them, they are much more complicated and not really practical for a bookshelf speaker.

So it's down to a two way set up. The C-Sharp speakers use DSA135-8 and ND25FW-4 drivers. I also looked at the RS150P-8 and DC28FS-4 drivers in the alternative design as they seem to be a step up in quality for very little extra.

The trouble is that I have no real idea of how to build a crossover, assuming I build the second one. I can solder well enough for this. I would have thought that someone would have designed a crossover for what appears to be a common combination so I thought I'd ask around here.

If designing and building my own crossover gets too complicated, I'll probably just go for the C-Sharps but I'm trying to figure out something that I will find challenging and enjoyable to build.

My sister is not an audiophile but there's nothing wrong with her hearing and she can differentiate between very average (think: plastic boom box) and reasonably good. I'm set on the amp, though I'm sure others would use something more advanced.

Any help would be greatly appreciated.

Cheers,

JD

Got some very old audio Technica cans and crappy Radio Shack crap. Thought about Jubilee not sure of brand but seems good for the price. Not sure if "critical listening phones" are right for me. Looked at AGS or something like that at a good price and old school. One is semi open air and kind of like that idea better than totally closed. Audio Technica or Sony are on my short list. Might even get dedicated low power high quality amp to get the most out of them. The A T are shorting out and refuse to subject my brain to the radio shack. Suggestions? On a right budget.

Greetings.

Apologies if this is obvious, but I have tried to find information on these tape heads and fell fully short. I have a bunch of these and have access to many more. I'm assuming they're Chinese.
I'm assuming they're for auto reverse playback because all heads have similar resistance value and occupy separate tracks.

I bought them to play with tape echo effects with a half-mind to use all four tracks.

Any information on these, however basic would be appreciated as this is new stuff to me.

Hi, I'm looking for info on those pcb.
I know member Tazzz had them for sale, but I don't see him active here since a while.?
I did two of those mosfets irfp240-9140 complementary amps and they are very good with a 250mA bias.
Or a similar project that I can use again the same output mosfets I have a plenty left.
Power supply.y +/- 40vdc is already built.
Thanks.

is it each fold in a transmissionline as you would (could) stack (2 if entering from the closed end) ,

or 3, if entering at the (~0.349 for the 3 x 1/4 notch/cancel) ? and have the driver (direct radiator) in the same exact spot (if concentric) as the vent.



also??


do you get ‘gain’ from the superposition of freqs that didn’t quite ‘make it past’the 180 degree deliberate turn? because they are similar in ‘sine wave size/shape’ so they promote output of similar input outgoing ‘size/shape’?


ignoring all of the super details and losses etc.??

(hope i worded this correctly?)

Looking for a pair of either the 15” or 18” BM series coaxials, now discontinued.

Problem
The frequency response of my system isn't flat. I want to fix it.

Plan
I want to add a notch filter to my tweeter and convert the 1st order crossover to a 2nd order. Then lower the crossover point of my mid woofer. This should allow me to crossover the mid and tweeter in the 2-3k range rather than 4k.

I'm aware that I'll need to measure the speaker myself to fine-tune crossover but I want to make sure I'm on the right track before I proceed.

Questions
1. Is it okay to remove the zobal network and replace it with an l-pad? I can use between a 7.5 to 10 ohm resistor in parallel with the mids.
2. The 0.55mH inductors and 10uF caps form a 2nd order crossover at 2.15kHz? And I can lower the capacitors to raise the crossover frequency?
3. I can raise or lower the padding resistors to adjust the mid and tweeter level if necessary?
4. Are non inductive resistors necessary? I'm sure they're necessary in radio frequencies but I'm not sure they're necessary in audio crossovers. Does anyone know the inductance of Vishay RS resistors?

Old crossover
https://elektrotanya.com/allison-acoustics_one-and-two_schematic_before_6-80.pdf/download.html

New crossover


Additional info

Speaker frequency response and impedance measurement
https://www.gammaelectronics.xyz/audio_04-1976_allison.html

Allison tweeter measurement
https://www.diyaudio.com/community/threads/tweeters-in-allison-loudspeakers.294463/#post-4835097

http://www.classicspeakerpages.net/...on_one_series_brochure_15.html#previous-photo

2 Mundorf Supreme silver gold oil 0.22uF 1000v
used, maybe 20 hrs on them

$100



2 Mundorf silver gold oil 0.22uF 450v
New never used

$60



2 Miflex KPCU 01 0.22uF 600v
New never used

$55



All prices include shipping to USA via priority mail
Sorry no international shipping
Paypal please

I known it is very old software but i want experiments with it, cpuld someone help me ?
thank you

I've seen some protection circuits but those are all smd and i cant solder them yet and was looking for any through hole verison.

Hi Everyone,

Curious if anyone has experience or preference between these two capacitors. The Vishay's are listed as Low Leakage and are very expensive. The Kemets seem to offer much longer life, and similar High Ripple current. What would you chose?

Thanks in advance.
Alex

Also known as Cubo HT is designed for Home Theater and low bass songs (B&B Bass Boosted). It extends into the realm of infrasound, frequencies below 20 Hz that are felt rather than heard, nothing too much just enough to justify its name. Experience (truly) scary low sound effects in movies or voice modulating bass lines in songs. Lots of amplifier headroom is advised but only a few hundred Watts is needed to get you started. Full plans and marketing talk here: freespeakerplans

The current plan for Cubo Infra is the 3th prototype, the measurements are from the first, although little has changed. An Imperial version is in the making, plans available on request.

The design allows it to be placed with the driver aimed towards its audience (or any other direction), with rubber feet of 2 cm (4/5”) height it can be used in a down-firing position. This maximizes the effective front chamber volume, creating an acoustical low pass filter that makes it sound like it drops lower and it can also mask mechanical driver noises.

The measurements below show the response in a corner*, in down-firing position, with a 24 dB/ octave Linkwitz-Riley low pass at 60 Hz or 80 Hz without a high pass. Based on hearing alone the response drops off quickly below 17 Hz. Of course measurements inside a room are very sensitive to sub placement, listening position and the dimensions of the room.

* One thick stone wall, one thin stone wall and a wooden floor

Front view:


Side view:


Down-firing:


Construction plan:


Cut Sheet:


Measurements:


Magenta: Microphone in close proximity, 24 dB/ octave low pass filter at 80 Hz
Purple: Microphone in close proximity, 24 dB/ octave low pass filter at 60 Hz
Turquoise: Microphone at 1 meter, 24 dB/ octave low pass filter at 60 Hz

Best regards Johan (a.k.a. Cubo)

I just want to share my small invention. As an experiment I made a "paper and epoxy" board markings. Yes, it's just a paper covered (and infused) with epoxy resin. The surface is not very uniform so curing under pressure would be helpful. The uncured resin partially dissolves the laser printer toner which led to a slightly fuzzy image.

I've always understood that having the tweet and mid as close as possible is the proper way to do things for all the various reasons you all know.

However, there are regularly speakers being designed and sold with considerable distances between the high and mid/midbass driver. Why is this done? Is it just for looks? Are the designers doing a tradeoff for some particular attribute?

Hello,

I am struggling with the audio quality of my home cinema for a while now, and I thought about changing the tweater of my towers.

I'd like to try ribbons, are there any suggestions for good ribbon tweaters (not too expensive)?
Since I need 11 of them I am looking in a price range about 90€ maximum, cheaper would be better.
I am going to try just two in the front towers for the beginning, measuring, building a new crossover and see how that goes.

I found loads from Dayton Audio, but is this maufacturer any good?
Some of them are super cheap I can't quite imagine those to be better than the original dome tweaters.


Greetings from austria,

Plempel

A Buddy gave me this non working amp to salvage the reverb tank from for another amp... In searching for a schem, I found that it was the go to for some famous keyboard plyers from the 70s,,, Steve Winwood,, Jon Lord and others,,,
So I thought I'd try to restore it, before stripping it for parts... I noticed a burned film capacitor,, trim pot and disc cap on the power amp board, and can't read the numbers...
I searched for a schem, but the only one I saw is unreadable,,, Anyone have a schem for this guy?

Thanks in advance...

Driver is mounted 1:1 and damp-duct 1:5.
Sound absorbing material is minimal.

I’m looking for available software that allows for measurement of Gm (GedLee distortion). I see that Virtins offers it in their full version.

https://www.virtins.com/multi-instrument.shtml

Also, according to Gedde’s paper (ref 5890), mention that frequency dependant Gm’s must be left for future work. Are there any software packages that allow for frequency dependent measurement of Gm?
@gedlee

So I bought a used Bugera 6262 (non-infinium). This is my first tube amp, and I don't know what I'm doing. It came with the original tubes, which must be pretty old by now. I'm running it on the 8-ohm setting into an 8-ohm 2x12 cabinet. The first couple of hours playing yesterday were great. Today nobody was home, so I put an MXR 6 band eq in the effects loop and cranked it up loud to dial in a tone. After about 5 minutes, 2 of the four power tubes were glowing bright orange and purple (the 2 furthest from the power cable, in case that matters). The other two were glowing, just not nearly as much, and only an orange color. After I noticed it, seconds later, I saw some sparking in the 2 bright glowing tubes and heard some noises, and the sound cut out. I immediately put it on standby, and after a few more seconds, the fuse blew, and the blue power light turned off. I think the two bright glowing tubes blew, and that caused the fuse to blow. I plan to order a new tube set, both power and preamp, and some fuses). I also ordered a bias probe, so I'll be able to set it properly. So my questions are; does this sound normal when tubes go bad, or does this seem like some other issue? As I said, this is my first experience with a tube amp. If this sounds normal and the tubes were just old and bad, are there any tube brands to stay away from? I was planning on ordering JJ 6L6s and JJ preamp tubes. Thanks for any advise or input!

So after the initial results of my prototype on Erin's Klippel, I was pretty excited to bring something pretty damn good to the DIY community. Unfortunately, Erin will be stepping back from testing for an indefinite amount of time. I'm having a tough time finding a Klippel owner that would work with me for a hobbyist price. So me and another member @tktran303 are both trying to figure out what to do. He floated the crazy idea of "let's buy one". So my question is, how much REAL interest is there in this community to measure your speakers for a nominal fee? Or do special tests there is interest in?

Hi guys!

A friend of mine has two beautiful cabinets, pretty much the same size as the sb acoustics Arya kit.
SB Acoustics :: Arya Kit

As we both are completely noobs with crossover design, we decided that the best we could do is to buy the kit without the cabinets, since the cabinets are identical (almost same baffle size, almost same liters) and we like the sound of the sb acoustics.
The bad thing is that the frequency response at the arya kit is very lame (see the attached picture)


I know that the cabinet, the position of the drivers and other stuff play important role, but my friend is not a perfectionist so, we are just looking for a better crossover design than the sb acoustics kit.
The drivers that we intent to use are sb acoustics sb29rdc and sb17nrx or Sb17mfc

Hi All,
Came across this psu & would appreciate your kind tutorial & explanation

1. Transformer is a Lundahl with HV 350 Ac output, not sure if it is 350-0-350v. If I use other tranformer with 350-0-350 do I leave the CT unconnected or ?
2. Does this hybrid rectifier circuit behaves like an SS diode bridge where voltage multiplication is higher as compared to tube rectification ?
3. What is the advantage of using such a circuit ?

Many thanks

Figured I would post here as a last ditch effort to attempt saving this amplifier I have. I purchased this amp used on eBay from a reputable dealer about 3 years ago. Unfortunately for me, all I did when I got the amp was hook it up for a minute to make sure it worked, but I didn't spend much time with it for about the next year or 2 because we were in the process of moving. About a year ago I finally got around to hooking it up, and realized at higher output it does this. As you're watching the video, you can see the woofers "flutter", and hear the song cut very briefly.

B&K Reference 4420 Issue

I sent this amplifier to a local repair guy, he said he couldn't make the amp do what I was describing, which made me wonder if I was going insane. I got the amp back from him and it does exactly the same thing. So I reached out to the best amp guy I personally know... in Portland, OR, and shipped the amp to him. He called me and said the same thing, he couldn't get the amp to react the way it was in my video, and he couldn't at all find anything using a "dummy load". Together, we finally figured out that the amp only rears it's ugly head when it has a real, 4 ohm load, the speakers need to be 4 ohm nominal to make the woofers do this, 8 ohm won't make them do this (and by "real" I mean it has to actually be a speaker connected to the amp).

The guy in Portland was fairly honest, he said he wasn't sure what was making this amp do this, so he was going to replace parts that were potentially problematic, hoping it would fix it. Long story short, he replaced a bunch of parts in the amp- fairly sure the only things that weren't replaced were the main power supply caps, and the mosfets, and replacing those parts didn't help anything at all. He believes this amp has bad mosfets, he thinks this is most likely what is causing this issue, but the mosfets for this amp are NLA. So gobs of money in shipping wasted, plus I paid him for some of his work, though he did give me quite a break because he felt bad he wasn't able to figure it out.

I'm curious if anyone here has any inclination as to what could be causing this issue? FWIW, the amplifier biases just fine, and sounds magical at lower volume. Once the speakers output reaches about 83 to 84 decibels, the amp starts doing what it's doing in that video I posted. And in case you can't hear it in the video, bass is what makes the amp do this, and usually that lower, more reverberant bass. There is no "smoking gun" anywhere, nothing in the amp looks burned and according to both repair techs, it tests fine on a scope. But the 2nd guy was the only one that could make the amp respond the way it was in my video. I really don't want to give up on this amp, it sounds magical up to the point that it has this issue.

I’m looking for second hand parts as to what makes and models
Bearing as to which bearing or what’s available out there
something a bit better than run of the mill
A stand alone motor and pulley
A platter to be run on the outside

I hope to make my own
Motor housing again I’m new to this but switch gear or transformer required
Bearing housing
Arm later on once the turntable is made
Arm housing

Any help or shove in the right direction would be appreciated


Cheers Jim

Having just retired I now have time to follow my past interests in the design and repair of audio equipment. Recently I have been asked to look at two Techron 7560 power amplifiers (sometimes referred to as power supply amplifiers), these are I understand equivalent to Crown M600 units. Their specifications are impressive, even by today’s standards. I have completed a couple of minor repairs and I have performed some basic tests to prove the frequency response, noise, output power and distortion (towards to onset of clipping I managed to get 1,500W into 4 Ohms (1kHz) at c.0.1% THD).

These units are switchable for a.c. / d.c. input coupling and are probably well suited for sub-woofer applications. However, they are large (6U), heavy 41.7Kg (92Lbs) and have two permanently on cooling fans. The owner wants to sell them and has asked, given their specifications, if they are something of interest to the audio community. I would therefore appreciate any views from the DIY Audio community as to whether these units are of any interest to community members. If so, and if my understanding of this forum works, I will arrange for the two items to be posted under the Market Place / Members Market area of the forum. This is my first post under the forum and apologies if I have misunderstood anything.

Your feedback would be welcome.

Jon

Hello,
I have installed the completely stuffed board from Hoppe's Brain into one of three GFA-565 that I am working on. It has no bias at all, it has sound and no offset. Noticed that R-502 runs pretty hot with 15volts AC drop across it (no DC, which I think is weird since there is a diode in series with the resistor/transformer ). Can someone explain how the bias delay circuit works and what the voltages should be? I was thinking of swapping one of the other soft start boards to see if it changes the condition. The manual just barey mentions the soft start board.


Just noticed that the circuit around R-502 is floating in respect to ground, so the dc thing makes sense.