Good evening (here) to all,

I’have two GFA 535ii’s, bi-amplificating my Tannoy’s. They are both perfectly working in terms of audio output quality but only one of them has a problem that I could not solve in any way.

The Power supply transformers of this one are audibly vibrating. There is no additional hum in the audio output signal but the chassis acts as a resonance box and when there is no sound in the room I distincly perceive its 50 Hz noise.

All electric parameters seems to be ok. The current absorbtion (signal inputs shorted) is the same, 360 mA, for both amplifier. The Transformers output Vac and the power supply board output Vdc are in line with the service manual. The Bias s ok for value and stability.

I tried removing the external metal (mu metal ?) band of the transformers with a little improvement. I placed a foam layer between transformers’ bodies and the chassis but this amplifier remains noticeably noisier than the other.

Has some of You solved a similar case ? I suspect that its transformer have been slightly damaged in the past (i bought them second hand).

Can someone give some advice ? Could someone, in case, supply me with couple of ‘new’ Adcom 535 Mk2 transformers ?

Thanks in advance to all for any help.

Selling two matched K75 250V capacitors, quite heavy and big in size, they measure 9.92uf and 9.70uf
Never used and in perfect condition. 18 euros the pair.
Paypal for friends. Located in Europe

Hi!
I have two old NAD amplifiers, a NAD 319 and a NAD 3100, each with their own problems..

NAD 319
This amp has had issues for a while. When in use, a humming sound starts building up and eventually becomes louder than the music playing. The noise' volume is independent of the volume of the music. I have more or less ignored this issue (deadly sin..?). The noise disappears if I slide an RCA cable across the inputs (so basically connecting their grounds together?), and recently I grounded the chassis to wall ground, which also seems to resolve the issue.. But I am sure this is not a very good solution..

Recently, another issue has appeared. If playing at low volumes, one or both speakers will either cut out completely, or at least start crackling at a very low volume.


NAD 3100
This amp never had problems before, so I figured I would use it as a replacement for the 319 until I potentially could fix it. However, this one also has developed some problems. When switching on, either none of the speakers work, both speakers work, one or both speakers might play at a very low volume, or a combination of these. It seems completely random which speaker works or not. By pressing the speakers A/B button in and out a bunch of times, I can eventually get to a state where both speakers play normally, but I would rather not have to spend 5 minutes repeatedly pressing a button..


Does anyone have an idea what might be the cause of these issues and what might be done to fix them? I also do not currently have an oscilloscope or a signal generator, only a multimeter and a soldering iron, so I am limited on what I can do. I am sure there are more details I should give, so just ask away. Thanks in advance for any help, and I hope my temporary fixes doesn't hurt you too much 🙂

As my old little mixer unit died and I had to settle for a $50- replacement I just picked up a cheap Behringer Ultragraph just in case I need to do any modification of the sound or I need to hump up the bass a bit.
I have assumed it went in series between the mixer and the DCX crossover but before I go out and buy some more patch cables I thought I should double check the flow sequence.
Not wanting to blow anything up etc:
I didn't know it had a mono sub output but I won't be using that feature at the moment

I am building a small (small as I can make it) board for Balanced-to-Unbalanced (and vice-versa) conversion. Everything fits so far as I used 22uF 4mm electrolytic bypass capacitors on the incoming rails. I usually see 47uF caps used for this purpose, but those are 5mm caps. I would have to enlarge the board slightly and redo my KiCad layouts to fit 5mm caps. Will the 47uF to 22uF increase in bypass capacitance REALLY make any difference? My power supplies are superbly well-filtered to begin with so I kinda doubt that it would, but I am wondering in case my design gets used in other equipment that has less robust power supplies. Opinions?

For or against establishing a sticky thread with a basic methodology, the necessary tools and the basic rules before any intervention, troubleshooting, upgrade, recapitulation, massacre, for noobs?

Like many here, I like to help with repairs but I'm more and more annoyed to see beautiful devices massacred or even destroyed following a "simple" recap.
We could first lay the foundations (for those who wish to participate), then gather the right information and then put them in their order of importance and create a sticky thread as a reference guide.
I'm very busy in "real life" but if we get together, we should be able to create this in a few weeks.
Tell me .

The CD player has always worked fine until recently. It has static noise in the left channel with both RCA and XLR output. There's still music playing in both channels (same volume). The CD player was fully recapped 2 years ago. Could a worn laser effect one channel?Any idea what might cause this?

Hi folks,

I have built SS guitar power amplifier based on Dr. Bora Jagodic amplifier Legend 100W.
I changed the circuit only by adding mixed-mode feedback to raise output impedance to about 24 ohms.
I have tested amplifier in rehearseal room and there is significant change in sound when amplifier is pluggen into 16 Ohms vs 4 Ohms.
Into 4 Ohms it sounds right, but into 16 Ohms there is too much bass and highs are rolled off too much.
What can be causing it? Oscillation?

Thanks for suggestions

Hello, I havent been active in a long time because life got in the way, was going to create a new account here then realized I already HAD one a long time ago when things were... better. 😛 (pre-corona world, more money available, etc.)

Anyway...

So i'm planning on building some PA speakers. There's no rush, because I wont have anywhere to store them for like a year, it's just what I like to call a "slow research" project. I might get busy with life for a month or two, remember I have the same problem needing solutions and come back, just so people know.

I'm a big fan of Bill Fitzmaurice's designs. Or at least i'm a big fan of his logic anyway, I mean it all makes sense to me. Short version I plan to finally order his all everything CD sometime this year and once I have the storage space start building things - even if i'm not sure what specific things.

What i'm wondering is what ELSE should I consider building, ordering plans for, or outright buying on the used market?


I should probably start over from zero so were all on the same page though. 🙂

I'm looking for advice for how far DIY PA speakers can take me. On one hand i'm between bands (for a long time now) but was wanting to get back into music, build some things up as a hobby, and eventually play smaller gigs. I've also been taking some sound production type classes going back to college after many years as well and slowly learning about everything up to power shaded inverted J-stacks - but i'm guessing for insurance reasons and other hassles flying speakers MAY be more than i'm looking to do. I would also like to have stuff to borrow to kids/nephews/friends if they want to go run a PA rig for a little side cash (not planning to really do this myself, too busy). If someone wants to rent it - fine with me long as it doesn't blow up - but it's not going to be big shows needing tech riders playing for 10,000 people.

Just because i'm learning more about HOW some things are done for bigger live sound I have no experience yet, so i'm totally open to well meaning advice steering me to consider other designs along with, or instead of, or just buying used gear.

I don't know how big of shows I will "need" to play, I don't know if the realistic upper limit for what i'm planning will be 500 people or 2000 people or what. Feel free to suggest though.

My most salient points and thinking process that steered me to Bill's stuff:

- #1 I want good sound. I've heard too many rigs even commercial rigs that suck. People should be saying "holy crap did that sound amazing".

- #2 all this including the woodworking itself to build, the gigs, and borrowing to others my PA gear is basically a hobby to start, until or unless it's not. I may build more equipment than is strictly needed for the smallest starting shows because i'm using speakers elsewhere when not at a gig or sending the nephew off with a PA setup while i'm playing somewhere else one weekend.

Strict analysis of cashflow isn't required at the outset for a hobby, things like the need to buy used name brand gear because you can sell it for what you got it for is not (at this point) my top priority. I'm also not trying to make pointless work for myself just to match what can easily be bought better I mean, like if building subs is smart but tops not worth the work, you can push me in that direction. Yet I expect to have two or even three complete sets of speakers to cover "small, medium, and 'large-relative' gigs" - I'd like to buybuild once and be set for the next two decades that I can say yes to any situation that wants to book the band that needs us to bring PA gear or has a questionable quality house PA. Ending up with 6 or 8 LABhorns, Tubas, or possibly 12pi's and the tops to match is not at all out of the question, but how big of a show will that play to blow peoples socks off? Much beyond that exceeds the hobby budget.

My assumption is even bigger gigs would HAVE a good PA to plug into, so i'm just looking for the system that will help "make a name" by saying Yes to any gig that calls and giving them amazing sound even if we have to haul it ourself to insure that sound.


- Now you might be already wanting to suggest speakers whose bass will make the gods weep but - we plan to self roadie things. After a night of playing hauling those cabs back out get heavier. I might be able to get another db or two from heavier wood but Bill's use of lighter wood and more bracing and smaller overall pack space makes sense to me. Also not having monster cabs with 2-8 drivers. Plus i'm less keen on stacking things three high for instance. Keep It Simple.

- Will need deep bass. I'm prone to things like Pendulum, but assuming a rig that will cover anything from rock thru drum'n'bass is a good plan, so his Tuba cabs over Titan cabs if I go Bill trading extension for outright efficiency matters. LABhorns? 12pi? I understand and accept that things like LABhorns are meant to run like at least 4 preferably 6-8, just tell me the space needed for monster bass. Yet systems that scale down for smaller gigs (or other speakers - I want to build some of his Tuba HT's for home theater too anyways, someone else used them for a PA in the corners and said they worked great) are also relevant.

- Pack space matters more for the small or/and medium rig because the large rig would have a dedicated trailer. If less than 4 LABhorns sound like crap we need a different speaker for those situations, also the idea of two speakers on more power with less pack space that might produce the same volume as four is nice on one hand, unless the cabs are painfully heavy or we dont have the plug power. I dont want to haul 8 LABhorns to every single situation, but i'm not against having different speakers for different gigs and loading the ones I need. If we have to go down stairs (and some places I expect to possibly play require that) those lighter Tubas start looking more desirable than a louder or more efficient 12pi, the latter may not even always fit either.

- Efficiency matters. I know Bill's designs push for efficiency, even if not absolute efficiency at all costs, but gigs with limited amplifier power are likely. But so is having more than one set of speakers if there's a big difference.



Lots of detail! Hopefully not too much. In my mind everything steers me to his designs - OR considering LABhorns - but i'm very curious what else is worth a consideration!

In looking for the next project I stumbled on to information about System Audio's design process of Pandion speakers. It seems that the designs were largely based on volunteer work and some or maybe all of the data was published on a blog.

I've seen that there were two versions: evolution and revolution. I understand that the evolution became Pandion 2 and revolution became Pandion 30. I don't know how close the final evolution/revolution information is to the Pandion 2/30.

I am having difficulty in finding the the designs of the final Q113 and/or Pandion.

Does anyone have diagrams/drawings/schematics/parts list for Q113?

Thanks!

SOLD

Asking $65 to include ground USA shipping. These are retailing now for $40 / each plus shipping from Antek.

For sale are a pair of Antek shielded AS-2218 200VA 18V transformers.

One is open package, I shortened the primary wires a half inch to twist them together for testing. Never used in an amp.

The other is still sealed in its box.

I still have my working original Hafler DH-200 and was thinking about doing a board upgrade. What are the latest options?

Hi there!
I am planning to build a couple of subwooferes for playing music aimed at the lowest notes, size limited to 200-220 litres.
And saw this driver by RCF, the LF18N408.
Xmax +/- 15mm. fs 30Hz
No comments on the web yet.
Has anyone used it?
I was planning to tune the box at 30hz.
Would it be recommended for this use?
What size to be used in a better way?
As well, seems to offer as well very good performance/price ratio both the Beyma 18PWB100 Fe and RCF LF18N405. Any opinions on those?
Thanks and regards from Spain.
Antonio

My friend went to Auckland, New Zealand to shoot a short film. Unfortunately, the sennheiser 8060 is working at all. So I came here to find the equipment hire. Can I get some help? Or if u guys knew some equipment hire shop in auckland, please tell me 🙁

Hi new member here.
Connected old Denon 8r integrated and 8 power amp which are biwired to replacement speakers without noticing they had jumper strips fitted. Blown internal fuse. Fitted the spare and that blew.

Any ideas on what I will have damaged and whether viable to repair?

Many thanks in advance
Mark

I removed the jumpers at the rear of the speakers before trying the spare fuse

The integrated amp blew . The power amp still powers up

Hi. Just finished the ACA mini build and biased it last night. Tested it with Schiit SYS and cd player and sounded good. Today, I moved some things around to make room for all the stuff, and one of the speaker wires came loose. Reconnected and now, when I fire the thing up, loud feedback/buzz/noise from one side (red). Any ideas what I should check appreciated.

I brought home a Yamaha YST-FSW150 powered sub from Goodwill for 20 bucks the other day. It runs well at low volume levels, but there's some very obvious distortion at normal listening levels and above, about 25% on the volume dial. With a sine generator, the resonant frequency is about 65Hz, and it tails off about 10Hz in either direction. The unit is from 2011—barely 10 years old. I'd like to get it working so I don't have to shell out for a new sub 😉

I don't hear anything rattling around inside when I carry it around, and sure enough, I found nothing loose inside the chassis when I took off the rear/bottom panels and driver. The distortion is the same in both the down- and side-firing orientations, or even if I lift the sub off the floor. The noise is definitely coming from inside the box, not from some piece of furniture. Pressing on different spots on the outside of the box (and down the inside of the port as far as I could reach), I couldn't find anything vibrating.

Taking any one panel off the box instantly fixes the buzzing, but also makes it not much of a subwoofer anymore. This means I can't just reach around inside and feel for the vibrating part, or even look inside while it's running. I think this at least rules out the electronics; it must be an acoustic/mechanical issue. However, all parts on the inside of the chassis feel 100% solid, so I have no clue what could be making this noise

The driver cone looks visually fine, and as mentioned, the buzzing completely stops if I break the resonant chamber by removing a panel, so I don't think it's blown out.

I've taken a few blind swings in the dark, to no avail:

• I ziptied some wires together to prevent them from touching the chassis walls
• The magnetic-shielding plate looked loose at the corners so I pried it off. (The glue was still completely fine in the middle, as I found out.)

What else could even be the source? I can only take the panels on and off so many times before the screw holes strip out, so any tips are appreciated.

Soul Note S3 Ver 2 SACD PLAYER
Soul Note Japan offeres me a unit of S-3 ver2. for demo
The shipping weight is 36Kgs..
https://www.kcsr.co.jp/detail_s3.html



[URL='https://flic.kr/p/2mU7Vf1']

Wondering about the sound system at Royal Albert Hall. Have a couple of recordings from there. One is a Blueray of David Gilmore and the other one is Joe Bonamassa. Have had the Gilmore recording for a few years. While the music was good the sound was not very good. Pretty much unlistenable distortion for me at mid and high frequencies. Always wondered if it had been recorded with one of the early digital snakes (a snake being the cable that carries mic signals from the stage to the mixing console out in the house).

Just got a copy today of a Joe Bonamassa CD set recorded at Royal Albert Hall. Reason for getting it was I heard music from it in a couple online listening session videos and thought the guitar sounded strangely metallic. Hearing the CD today reminds me of the David Gilmore recording. Don't think I will play the Bonamassa CD more than once. Would like to enjoy the music, but hard to put up with the ugly (to me) distortion.

Anyone else notice this? Is it a feature of Royal Albert Hall recordings over some time period? Just wondering.

Free, just pay shipping. I'm in UK but happy to post anywhere.

FS a pair of SB Acoustics 7.5" Satori TeXtreme 4 ohm

used very little

price 429 euro

Please PM

Looking to purchase two of these for a project.

I’ve read various blog entries about the LM3886 and the circuits people have made

Two suggestions I’ve seen that don’t always seem universal are the following, and I’m just curious how often they are implemented?

1) the data sheet sort of makes a passive mention about a 220pf capacitor between the inputs to help with oscillations, especially with those that come in via the input terminals. Is that pretty standard? I don’t see it in a lot of PCBs, so I’m guessing the ones who do it solder directly to the lm3866 pins?
2) I’ve also seen mention of putting a larger 100k resistor between the input and ground, but before the DC blocking capacitor. Apparently this helps prevent the capacitor from accumulating a charge when no input is connected. What’s the side effect of doing vs not doing this?

Thanks.

I recently managed to blow the left output channels on a pair of 3BST amplifiers (most likely due to inadvertently touching the ends of the speaker cable together while under power. Face, meet palm...). Both internal and external fuses blew on the left channels, along with a number of output transistors. After talking briefly with Bryston tech support, I consolidated the two working channel modules into one functional amp and set about repairing the others. I've managed to replace all the transistors on the bad channels, put the respective channel modules back in their proper amps, re-bias the transistors, and adjust the DC offset down to somewhere under <1mV. Amp #1 seems to be working fine and, if anything, sounds as good as, or better than it did before. Amp #2 appears to give correct bias and offset readings, powers on normally, and initially gave a rather feeble output signal on one channel and then quietly crackled into silence over the course of maybe 20-30 seconds, and now refuses to produce any output whatsoever. I put a cheap oscilloscope on the outputs and, as expected, it's a lifeless, flat line. It's rather odd that both outputs are non-functional, since one was working before when installed in the other amp. So perhaps something beyond the channel modules is bad.

At this point, I'm hitting the limits of my diagnostic skills, and am running out of ideas. Can anyone suggest what I might check next to get a better idea of what might be going on here? A month ago I barely knew which end of a multimeter to point at a circuit, and now I'm reading technical whitepapers on class AB amps. I'm not experienced, but I'm a quick study...

If anyone is interested in this instrument PM me and we can discuss price. It is undamaged and in working order.

Cheers,
ceulrich

I have a somewhat specific question.
it is said that the karlson cabinet makes the loudspeaker work so that the reproduction of the sound can take place with smaller cone excursions compared to loudspeakers placed in other types of cabinets.
I think that this effect is generated by the air pressure that is generated in the chamber of the cabinet.
I would like to know what the loudspeaker coil does, what it does and how it behaves in this case, ie when the loudspeaker coil moves less. Back EMF for example.
this type of loading has characteristic negative effects, two cancellation peaks typically located at 180Hz and 600Hz.
this question is asked because I would like to understand if an amplifier with motional feedback can remove the two cancellation peaks.

Hi guys!
After long research,discusion and space menangment,plan is finished!
I'm gona build a sealed subwoofer,in box of 120l. In that 120l is everything calculated,driver,bracing,damping.
Woofer is Eminence Kappa pro 18lf-8.
Yamaha P3200 in bridge mode will be power monobloc for woofer.
I'm also gona make linkwitz transform in try to get as flat as posible down to 20Hz.
Woofer is big,amp is big so i have place for at least 20dB gain if needed.
I will use woofer in home setup for music,maybe some time for movies,but music is first plan.
Woofer will play L i R chanel in mono mode,it have only 1 coil.
And that will be help to my Dallas II with Fostex FE206EN and Monacor super tweeter driven by KT88 SE amp.
They play almost flat from 55Hz to 15000Hz,+/-3dB.
I'm happy with that but i want low end.
For now i put woofer in H frame,and its driven with subwoofer modul 150W 8Ohm,with activ crossover. Its ok,but is not linear and i think that can be much cleaner without thos subwoofer module.
So,the only thing wich is left undefined is crossover,low pass filter.
What to use for that purpose,what will you use in this situation and why.
Passive or active? I know there are nice analog active crossover,but 3k€ is waaaay to much for me in this situation.
I will take signal from KT88 SE speaker out,paralel with Dallas.
So im not sure what to use. Some old speaker builder,from MIR AUDIO told me to use passive and nothing else,that everything else will color signal.
And if this is the best way to go,what to do with phase if in the end i need to switch it?

Hi friends
I have got myself a pair of speaker wires, a Mogami 2804...
That's a rather thin, stiff, expensive little diva of a beast. (I like it 😛 )
But I'm worried about it wearing out due to mechanical stress (plugging, weight, inadvertent pulls etc.), and am looking for tips about stress-relief techniques. As it's a coax with each "lead" (outer/inner ... core?) going into its own banana or spade connector, how can I mechanically improve these last few cm ?
Thank you

Hello,

I recently obtained a pioneer sx-110 (1965 manufacture date). It has 7868 finals. I’m studying the schematics before replacing all the original (bad) paper-oil caps, and they suggest a rather unusual operating point compared to all other 7868 receivers and amplifiers I’ve looked at. Unless I’m reading something wrong (or the schematic is wrong), it looks like it has a really high B+ for the tube, yet a low quiescent current.

I see 495v and 94mA going to all four plates; or 23.5 mA for each tube.

Usually, for other amplifiers using the 7868, I see B+ around 425-475ish and 35-40mA-ish going into each tube.

Other pioneer receivers or amplifiers from the same era with 7868 finals seem in line with just about every other I’ve seen:

SX-2000: 460v, 35.75 mA
SA-810: 425v, 36 mA

Whereas:
SX-110: 495v, 23.5 mA

Here is the relevant part of the schematic. Could I be reading a number wrong? Bad math? Could it be a misprint? If it’s correct, what do you think the designers were going for with high voltage but biasing the tubes rather cold?

Thanks for the help!

Hello guys, i want to change the internal wiring to improve the singlas quality ( rca->selector->potentiometer->premamp->ampl) . Do u have any suggested wires thay i can use ?

Hello all, new member to the forums.

I am currently building my firsts DIY subwoofer. Sub will be sealed in a small 1-1.5 ft3 enclosure. Sub will be passive, with external amplification. I will decide on final enclosure size when I am better familiar with WinISD. I have a mini DSP HD which will be performed EQ.

In addition to the build, this will be my first foray into woodworking. I tried mocking up a box with the skill saw, and all my pieces were cut poorly. I have amassed scrap wood to practice cuts. Given my poor skills, I bought a cheap driver to fool around with. Until I am confident, I can build something decently.

Driver: https://hertz-audio.com/product/car-audio-subwoofers-uno-s300s4/

So right off the bat, in WinIsd, I made three of the same units all with a 1.5 ft3 box. The first is the box with no eq or filters. The system input power is ~200W. The driver can handle 250W RMS, but cone excursion hits the limit in this box size.


In the second unit, I applied a Linkwitz Transform. I did some reading. This is optimal for sealed boxes. I want to learn more about the LW Transform and have had difficulty finding literature online pertaining to its application in WinISD. The stock box is shown with the lower transfer function magnitude. Speaking of which, what parameters do I change in the LW transform? Or is it best to leave stock? Which is what I believe I did.


In the Third box, I applied parametric EQ with a 6DB boost at 30Hz. It looks slightly better than the stock box, but all of them look horrible compared to the LW transform.



Now for the part im having difficulty with when looking at cone excursion. The stock box handles 200W with no issues.


LW transform is okay until you hit 20Hz. Anything below will blow the driver. Input power has to be turned down to an abysmal 5W.


Parametric EQ with 6Db boost. Wattage has to be lowered to 50W. I am guessing because this driver has only a tiny 250RMS handling and a small X-max of 9MM. Is there not much room for improvement?



I am completely lost on the SPL plot. I can see the boost at 30hz on the Parametric eq, and the LW transform plot is the flattest of the bunch. However, The stock box still has the loudest SPL at all frequencies above 20Hz. Looking back at the first chart (Transfer function magnitude). How do I go about interpreting The best DSP for my box? I have yet to fool around with high-pass filters. I would need some insight into best practices. Or where I can find resources.






I am new to audio.

Apologies in advance if this was posted in the wrong forum. I wasn't sure if this was more of a subwoofer post or a SOFTWARE post.

Hi,

Looking for a couple of 2SC1681's NOS anyone have any?

I am using audio interface to measure THD of the amplifier and I run ARTA on my PC.

When I connect amp out to the input of the audio interface I get a lot of interference.

Is there a proper way to do this?

Below is the schematics how I currently have it:



I am using Focusrite Scarlett 2i4 audio interface:

Dear all,
I would like to build this speaker here:
Faital-3WC
Since I am a Newbie, I have a few questions.

1. The wood used should be 20mm Baltic Birch Plywood. However, I checked many shops but this is basically not available here... only alternative is Beech Plywood 20mm. Do you think this can make a severe difference?

2. I would like to buy the crossovers from the page. However, I think the price differences between two similar sets are extreme. Please compare page 1 and 3 here.
http://www.jantzen-audio.com/wp-con...-Way-Classic-All-kit-versions-with-prices.pdf
What do you think, how relevant is this? I mean, about 700€ for a slightly different material? Will I hear this? Is it worth the money?😕

More questions will follow soon I guess... thanks a lot, any help is appreciated 😀

It pains me to admit I efffed up, but I want to spread the word to others here so they don't make the same mistake.

I added weight to my Emimence KL3012HOs to get the TSP specs and efficiency where I wanted them so I could cheap out and not order the C0RRECT drivers to begin with. The woofers were going to be used as the LF in a 2.5 way along with the KL3012CX coax drivers. Well, against my instincts I used Neoprene loaded adhesive (aka 3m weather strip adhesive) as it stays flexible and can be gradually added to obtain exact weight. YES, I SHOULD HAVE USED EPOXY, but only had the grey JB weld on hand, which shouldn't be used on the moving assembly of a speaker due to it containing iron particals as filler. Anyways, I embedded a coil of 12 awg copper wire (loop not closed to avoid a shorted turn) so the added weight came to 13 grams. Everything went well and I got the weight bang on. I've used this technique a few times before with success, but with liquid glue, not this thicker consistency stuff.

Well, now the part where I found out that I screwed up - I put the drivers on the sine wave gen and swept with 16V. The first one was perfecf, but low and behold I had a noticeable resonance spike on the other in the FR curve at 1 k. This turned out to be the copper loop buzzing on a spot where apparently the glue didn't get or stay in between the copper and cone. I tried injecting cyano glue and retesting, but the buzz was still there. I then tried cutting a slit into the glue and adding more cyano, but it was pointless. The other driver is perfect without any issues.

The moral of this story is ONLY USE EPOXY to glue anything on the moving assembly of a speaker (poly cones excluded). Otherwise it will end up buzzing or making other undesirable strange noises which could only be detected by THD measurements. Now I'm stuck with 2 paperweights to the tune of over $500. I feel like a complete idiot.

On the plus side (if there is one), I put the one driver on the sine gen and ran the driver at 40V free air around 100hz. Couldn't kill the thing running it there over 5 min which is a testament to Eminence durability. However, the suspension was so stressed at that point it was worn out and felt like a woofer that played for several years at full power in a dive bar. The KL3012HO is not a good dedicated LF driver, but rather a midbass. It should not be used over its small xmax limit.

Now I'm stuck ordering the correct drivers i should have to begin with (KL3012LFs). I may recone these others but Eminence doesn't usually sell recone kits for these outright. I may have to ship these to Eminence. Oh well...

Just another of those idle thoughts I get sometimes.
But if the floor space isn't available and the boxes are not too heavy would mounting HT subs up at the wall-ceiling boundary be any different?
Something to ponder perhaps if mounting in the roof cavity isn't an option and WAF was high

a friend has one or two of them or a mono version (- guy did not fully explain and I've seen the amp nor pictures other than someone else's blog for S120) - one channel (or amp?) needs repair and the company that built them does not supply schematics. They had a extra output terminal for use with a motional feedback subwoofer.

When the amp owner talked to a service person there was some mention of Sanken outputs which aren't made anymore but some output were made in California.

A sketch or service schematic would be greatly appreciated

sorry not to have better details.

Here's a blog on the amp

https://www-cfc1962-it.translate.go..._sl=it&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp

Hi
My Dynaudio D28/2 tweeters are over 20 years old, and I'd like to get them repaired or find
replacements; however, Dynaudio components are no longer being sold.
Anyone know where to get repair/replacement?

There have been sellers of "David Louis D28S" (and other models) tweeters on e8ay over the past several years. Most recently they claim iin their listings:

"The 28MM dome made from the same factory as Dynaudio...
Sound style: natural, detailed, and transparent.
sound very close to the Dynaudio style"

I am interested, but sceptical. When the D.L. tweeters cost <$30 I ignored them. Now its $75-$145 ea!! They must be better now(?)

The data in the listings appear to be generic, and I haven't located any reliable test/results.
Anyone here try these, have experience or know anything about them?
Thanks.

This may be an oddball question, but I'm asking it in earnest:

The horn on my EAW speakers is made from two pieces. Where they come together is very far from smooth. In fact, there is a very noticeable "gully" that runs the entire length of the horn, front to back, on both the top and bottom. (FWIW, this is on a BMS 4594 coaxial)

It seems to me that this should be smooth, and I'm wondering if this could be physically affecting the HF response / dispersion a little bit?

If so, would it theoretically be a good idea to try and fill these gullys in?
And if so, what might do a good, permanent job of it? (It's very slick plastic, of course.)

Neotech NEP 3003 power cable terminated with Furutech USA main plug FI28M(Gold plated) and USA C13 IEC plug FI28(Gold plated).

FI28 series connectors are most selling product of Furutech make a very positive connection with a tight fit.

Neotech NEP 3003 is made of 3 conductor(13 AWG each) Ultra pure Ohno Continuous Cast copper. This is very high quality shielded cable from Neotech.

It always sounds musical and engaging without any harshness or treble grain.
Excellent for preamplifiers, DAC and source components.

Cable length is 1 meter and professionally build.

Cable is fully Functional and cosmetically in good shape.

Neotech wire is light used and Furutech connectors are bit old(3.5 years).


Selling at very reasonable price of $130 including PayPal fee 5.5%.

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AudioQuest Mistral power cable terminated with Furutech USA main plug FI-11M-N1(Gold plated) and USA C13 IEC plug FI28(Gold plated).

FI11 and FI28 series connectors are most selling product of Furutech make a very positive connection with a tight fit.

AudioQuest Mistral offers greater sustained current flow via its large 3.31mm2 conductors consisting of a combination of Perfect-Surface Copper+ and Long-Grain Copper. This combination increases the current of power entering into equipment (such as amplifiers, streamers, cd players etc.) and ultimately improving dynamics while reducing noise-floors within system.

Overall sound signature is greater clarity with a wider soundstage, breathtaking dynamic range and non-existent noise-floor.
Excellent for Power Amplifier, preamplifiers, DAC and source components.

Cable length is 1 meter and professionally build. Black color Techflex braid is kept on cable for nicer look.

Cable is fully Functional and cosmetically in excellent shape.

AudioQuest wire is light used (6 months) and Furutech connectors are bit old(2.5 years).

Selling at very reasonable price of $170 including PayPal fee 5.5%.

-----------------------------------------------------------------------------------------------------------------------
Shipping to Worldwide at buyer's risk, but it will packed carefully.
Please contact me for shipping charges to your location.

Thanks for looking.

FOR SALE one KEF T52 SP1049 Tweeter
I bought one NOS condition unit for spare in oprder to restore a pair of old Kef 105.1 And I realised that the problem was not the tweeter but the crossover. A dead cap.
So, I have KEF T52 SP1049 Tweeter for sale as long as I won't use it.
I'm asking 80€ plus shipping and Pp costs if they apply.
Although the seller at ebay said it was never used you can see it's been installen adn there are some marks in the dome, but I have tested it and it is in perfect working condition.

I have an audio, two channel, potentiometer that I removed from a tube amplifier kit I built a while ago. Adding it to the ACA Mini would there be a decrease in volume? Does adding this potentiometer introduce anything negative?

Hi,

I was given pair of Alesis point 7 monitors. They seem well built, but when mixing in reverb I noticed plenty of the higher frequencies, but a bit empty where the richness is. Is there a change of components in the crossover that I could do that could help? I wouldn't want to change values, but upgrade quality.

Could I ask for advice on which components, if any, could provide a more natural sound?

Thanks

Hello everyone,

Does anyone have the schematic for the SFL-2 preamp PSU? Or, the Service/Repair Manual?

Thanks in advance for your support.

Can someone put these to use? I've been converting my First Watt clone amps to the H9KPXG switch/soft start. These terminal strips with CL-60 are no longer needed. Yours for the cost of shipping.

This is my recently finished copy of the Aleph XOno. I finally had time to have a proper listening session earlier this week and get the cartridge loading and gain settings to where I was satisfied. The time and money spent was well worth it. I really can't see me needing to make any other phono amp! It is so, so good.

My next challenge is to bring the rest of the system up to same standard as it is streets ahead of my Naim set up.

The boards came from Willkommen auf meiner DIY Audio Homepage - RStAudio.de and are of excellent quality. His documentation and support is also excellent. You will notice that there are no 10uF capacitors at the bottom of the board. These have been replaced by DC servos with very good effect.

We had the best car racer: J.M. Fangio.
We have the best football player (Soccer): Lio Messi.
We had the best football player (Soccer): D. A Maradona.
We have a queen in Holland: Máxima.
now, we have an Argentine Pope.

Next steep: the forum, ja ja ja...

Congratulations and good luck Jorge Mario Bergoglio!, although I'm atheist.

Even though the power switch is OFF, when I connect or disconnect the input, there is a loud noise in the speakers. Is the ACA Mini powered up all the time, even with the power switch off.......Or did I do something wrong in construction?

Just in case someone needs this!

Hello all, I bought a stash of 6021 pencil tubes a long while back. These are low plate voltage, medium mu (35?) dual triodes. I have been reading up on them and many generally like them a lot...they are designed for really abusive military environments.... I get empty 9 pin bases and solder them into the bases as 6922 pinouts (9AJ base pinout) and then fill the base with hot wax....So I jumped on them when I found a bunch of them NOS cheap....I have used them in the pole position in my Aikido pre (230v B+) with 6922 or 6H30 in rear seat...

Anyway I have a Knight 600 tester and looking for the 6021 settings...nothing...I can use the 6922 settings, but resulting numbers are somewhat all over the place (understandable as these curves are exponential)... does anyone have the settings or can offer up another tubes setting that is closer to the 6021 that I can use to try to better match these tubes? Datasheet attached...

I have another Aikido (Aikido LV) with 24 Volts B+ intended for certain tubes that work great at very low plate voltages (6GM8/6N27P/ECC86)….while waiting for these tubes, I put in a quad of somewhat matched 6021 (in 9AJ basing)....works / sounds fine, but temporary...or maybe this tube is perfectly fine in this low plate voltage application....

Hello everyone,

I wanted to build a 3 way speaker. For the lows i wanted to have a sealed enclosure. Its quite hard to find drivers for that but i fond a really nice one.
https://voltloudspeakers.co.uk/loudspeakers/sb220-1-8/

Heres the thing: I want it to crossover between 600-800 with my bliesma M74S.

BUT: They call the SB220.1 "optimised for bass performance in sub-woofer applications" or "Sub Bass Driver".
Is this just marketing? Or will this driver be as good in the low mids as others? Is there something I dont see? For the Frequency range they even say 25-1000hz.
Their actual mid bass driver BM228.8 (https://voltloudspeakers.co.uk/wp-content/uploads/2017/11/BM228.8_v1.1.pdf) doesn't even look that good in the response curve vs "the sub".

Thanks everyone,
Johannes

Relay: PCF-1224D2M
Does anyone know where I can find this type of relay or a replacement?

Hello!
I need some good circuits (PCB) which based on 2N3055... How much power is possible to get with these? 😕

I was breaking down my pile of crappy speakers for parts. One of the vintage speakers had the driver mounted behind this honey comb hole pattern. This is a lot easier than trying to cut a perfect six-in circle. I assume it has drawbacks does anyone know what they are?

Howdy folks, gonna try to sum this up quick as I've got some other threads elsewhere on it.
Built some C-notes, measured at the end to confirm performance. I was getting a HF shelf boost. PE offered to measure the speaker to confirm it's working as intended and they did so. It appeared to measure pretty much like the advertised spec. I ended up considering my EMM6 might be off so I had them replace it. I went ahead and measured them with the new mic and the shelf is still there. This is strange to me because I was informed that the omnimic PE is using in house is calibrated the same as the EMM6. I've got some speaker projects that have been on old because I don't know how if I can trust my EMM6. I was speculating that it's from pointing the mic at the speaker, and that rotating it so it's facing up might show more accuracy. It kind of starts lining up with PE's data but the shelf is still there, just lessened.


Here's my own outdoor data with EMM6 pointed at the speaker.


Here is PE's data. I was told it was an omni mic pointed at the speaker. Black is original, red is mine.

For Sale ultra low distortion audio range fixed frequency sine oscillator.
More information here: https://viccc42.wixsite.com/uld-audio
Assembled in aluminum chassis with SMPS.
The performance of this oscillator can be improved with a better power supply.
Price: $60 USD includes shipping to 10 provinces or 48 states.
PayPal please add 3%.

Good day. All the right channel transistors in my Mc2500 have been damaged in the amplifier for a long time. The right channel transistors on the heat sink.
Transistors in Power Circuit:
NPN, MJ3247
PNP, MJ3237
NPN, DAR, MPS-A14

I am not able to find these transistors or alternates online at all. I want to get good quality ones for proper repair. Please, does anyone have any suggestions on this?

Hi,

I've a serious problem with a Cyrus PSX-R power supply, version 2, connected to my Cyrus III amp. This device normally is able to supply two regulated voltages (+35v and -35v) to a number of Cyrus amps.

The problem: increasing the amp volume, after a certain level the positive voltage progressively collapses to very low values and obviously the sound becomes awfully distorted, and even disappears. Instead, zero problems about the negative voltage. This happens only when the amp is connected to the loudspeakers: in other words, depending on the current request.

From what I've understood, a positive reference voltage (+3,5vdc) is submitted to a NE5534 op amps and here multiplied by 10, in order to keep a regulated output of
+35volt. This rate is in fact respected, as it's the positive +VREF that collapses first....

For information, the source rectified voltages to be regulated are +/- 48vdc, through a massive transformer. The output transistors are two parallel 2SD1047, driven by a MJE243/MJE253 couple

Any idea about the fault? How could I investigate furtherly?

Many thanks in advance to everyone

Say hello to my new (old) Marantz 1250. The sound out of it lacks any dynamics, so I figure it needs a recap. I've received some advice from AudioKarma to replace all the tantalum caps along with the electrolytic caps. Any suggestions on capacitor choice, brand or otherwise would be greatly appreciated.

I'll be updating this thread as work progresses. For the last few months this amp has been sitting in my living room with dryer sheets inside it to get rid of the musty smell. There's a little bit of rust in the unit that I'll be sanding out and repainting as well. I'll post a full teardown along with component order from digikey when I can.

Hi Pass aficionados, I am searching for Pass amp circuits, single ended, that use a split resistor in the current setting of a current source load to double the class A output current. Needed as reference for an article.
I believe Nelson called them active current source or modulated current source, although the latter is also from one of his patents which has a different topology than the one I an looking for.

Ring any bells?

Jan

Personally I have 32 Ohms headphones. When impedance is 32 Ohm and lower, there is really no need of voltage gain. This is why I suggest a buffer, a voltage follower.

My circuit is such a follower.

There is no feedback loop. It is only current gain. P1 is used to set the output at 0.0 volt. For no DC-offset.

The output is one current source. There is the possibility to increase the current in output stage. By adjusting the R4 resistor. For my 32 Ohms headphones it is not necessary. 50mA is enough. But we can use for example MJE15030-31 in the output.

BF245B was chosen for the availability. And low price. Can be used for 30V. So, maximal power supply should be 2x15VDC. Regulated is recommended. For example use LM317T/LM337T.

Hi,I want to ask if anyone knows where I can find the service documents of the Wadia dacboard, which is used in the Wadia 381i, s7i and 521dac models? The dacboard part number is 103356-006A

I was running my Sony TS-W308-D4 (400w rms / 1400w max) at 2 ohms on a Kenwood KAC8105D amp (300w @ 4ohms, 500w @ 2 ohms, 1000w max). The volume wasn't turned up very high and I honestly can't tell you where the gain was set at when 'pop' and the sub quit working properly. Now the woofer barely moves and is muted. I checked the voice coils and they both now read around 2 ohms (1.8 & 1.9) when they should measure in at about 4 ohms. Do I need to replace the voice coil(s)? Where can I find replacements? The sub is in very good condition other than that. Newbie here and any help would be appreciated. Thanks

Anyone have a working quad they could unload? Let me know...

Modding STA-based digital amps

My recent blog posts on digital amps from Taobao, specifically one based on the D2-41051 (Intersil) and the other based on STA333BW (STM) have generated a fair amount of interest so I figured it might be time to start a thread rather than simply entertain comments on the blog.

The SQ of both of these has impressed me, but not in stock form. I've focussed so far on mods to both the power supply and the output stage as this is the low-hanging fruit. Other mods are not being excluded simply because of my initial focus on these areas, there may be digital/clocking mods which turn out to be worthwhile too.

Come to think of it, I think this thread might be more appropriate to classD as its about what's in effect a power DAC.

The STA333BW board has a maximum power supply voltage of 21V (from the datasheet of the chip) so adapting it to work with step down transformers doesn't give much latitude before the available power output becomes impracticably low for speakers (though still oodles for headphones). I have two 2:1 step downs re-wound on EI 15VA cores which give this amp a very relaxing 'analog' or 'valve' sound when the power supply is beefed up - shown in the snap below. However the available output power then is under 10W per channel.

The 'hexacap' under the board is an array of 65 680uF/35V caps and there are short 1mm dia solid wires linking the cap bank to the underside of the STA333BW chip. The 'valve' sound arises in part due to HF roll-off caused by the output transformers having rather too high leakage inductance. I've measured this and its fairly substantial - something like a first-order pole around 4kHz.

<update - changed thread title to reflect only STA-based amps, my mods to the Intersil-based amp I'll open another thread for>

I'm in the processes to design a RIAA amp with both MM and MC capability but I can't figure out (using Google) which ranges of capacitance and resistance I should have. The plan is to have a 8 position DIP switch for each channel. My Ortofon FF15 needs 47 kohm and 400 pF load but how about the MC cartridges?

(I will show my work later on 🙂 )

Up for grabs as my current speakers like a little more power are these widely discussed on here monoblock amplifiers.
A la industrial style 😊

I have replaced the caps on the board and swapped out bnc sockets for rca .

These are a matched pair ( a left and a right)


I do not have any specs on them but helpful members on here helped me establish that they’re approximately 100w each .

Large can caps are still within tolerance.

Toroidal transformer hidden under the metal shelf.
No pops, bangs or hums and they’ve never missed a beat .

I’m uk based and they are for collection only I’m afraid.
Any questions please pm me .

£400 ( for the pair ) someone did ask if I would split them ! 🤣

I’ve been trying to track down some pesky rectifier noise in one of my amplifiers. I hooked an oscilloscope up to the speaker connection on one channel and noticed some periodic spikes in the signal with no music playing. The spikes are roughly every 5ms, so 200hz. I sort of thought this might be rectifier noise since I live in Europe (50Hz) and I have two bridge rectifiers in the PSU. Despite all my efforts of moving the grounding around, I couldn’t get it to go away.

Then I decided to take a break, and shut the amplifier off by turning off the smart plug it’s connected to (which kills the power but leaves earth connected), and surprisingly the spikes didn’t go away. I then started unplugging devices one by one from the power bar that powers that area of my entertainment center. In general the more devices I unplugged, the smaller those peaks got until everything was unplugged, and all that was left was the background noise.

I’m trying to figure out what the cause is. Is it really just a bunch of rectifier noise that’s been passed onto the earth connection by random devices on that outlet? If so, any way to counter that inside the amplifier (ie use a ground lift or something?)

SOLD

Asking $165, $125 which includes USA shipping.

I will not be building another SIT amp so these are for sale. I used another pair bought at the same time from Watanabe and they have functioned without a hiccup in a Zen Mod type amp.

I bought these a couple years ago, as "roughly matched, no curves".

I will ship carefully packaged.

After seeing some pictures of an open Vendetta 2A and contributing a bit of imagination i ended up drawing approximate circuit diagrams. Ok, i also saw Federico Paoletti's circuit of the 2B but it didn't look too plausible. In any case they seem quite different.

Of course, not everything can be clear from photographs. Please take capacitor values and fet types as guesswork at best - they are mostly based on Mr Paoletti's values.

All the same a very interesting and unusual circuit. Unless someone spots a glaring mistake i may even attempt to build it with whatever substitutes i find.

Ok, the idea is by no means mine, but anyways...:
I'm currently working on a big mancave horn system that needs to be XO:ed at around 60-70Hz.
Right now I's using a DIY 70Hz 12dB/Oct Linkwitz-Riley crossover that seems to work quite ok but I'm not too excited about the build quality, especially since it's been modded to within an inch of it's life by now.
The whole rig is built in a retro 40's style (think Altec Voice of the theatre) so using a DSP would be almost blasphemous, even regular opamp based active crossovers would leave a nasty itch in my brain.

Would it be completely insane to try passive line level LCR filters as crossovers?
I have some Hammond 156C iron core chokes on the shelves (150H, Rdc 3,8kohm) and a bunch of precision 40,2nF polyprop caps. If my maths is correct, 150H and 40,2nF into a 30,5k load would form a 65Hz L-R filter.
My sources are CD and computer soundcard into Sowther TVCs, so the source impedance should be low enough to drive sucha crossover I believe.
Any thoughts on this?
I know Marchand sells something like this, I believe it's called XM46 if my memory serves.

I am building a little single 12AX7 tube preamp for bass guitar , and the output is way too hot so I am going to put a voltage divider attenuator between the two triodes. I have been looking at a schematic for a Gallien Krueger amp that uses several 12ax7 in the preamp and then uses a voltage divider 1M / 100k to reduce a 22v pp output to 1.9v pp. So I think it's ok to do something like this , but then I'm thinking of other amps that use bypass caps on volume controls to retain otherwise lost treble. Now I realise that a bass guitar signal doesn't contain much high frequency , but then there are harmonics and so forth that do give a bass guitar an "airier" sound , and I don't want it to sound boomy. So , depending on how much the voltage is reduced , how does one know what high frequencies and how much of those higher frequencies will get attenuated, over and above the attenuation of the other frequencies ? Or is it more of a psychoacoustic thing? Or is the loss simply negligible as far as a bass guitar sound is concerned , even when cutting the output by 90% as the Krueger does?

my subwoofer stopped working, I assume the issue is in preamp board, if you have one and willing to part with, please contact.

I've built a few LM3886s essentially based on the datasheet, and Tom's useful web pages regarding the amplifier.

For my first builds, I used an input resistor of 20K, a DC blocking capacitor of 4.7uf, a feedback resistor of 20K, and the current balancing resistor of 1K at the input.

This works and sounds good, but I'm wondering if I can do a bit better, while making a few changes.

1) The 4.7uF capacitor is massive. It takes up about 1/4 of the PCB by itself. I wouldn't mind lowering it to 2.2uF as this gives me more breathing space on the PCB to move things around
2) Tom's guide 'Complete Guide to Design and Build a Hi-Fi LM3886 Amplifier' says you want to balance the input currents against the feedback current.. I have 20K + 1K on the input, and 20K on the feedback, so while it works, I wouldn't mind making this exact on the next build.

To that end, I've debated the following changes.

1) Change the input resistor from 20K to 23.7K
2) Change the feedback resistor from 20K to 24.9K
3) Change the gain setting resistor Ri from 1.0K to 1.2K, keeping the gain really close to what it was before
4) Change the input current resistor Rb from 1.0K to 1.2K, making the current exactly balanced (23.7K + 1.2K = 24.9K)

I calculated that the change in the input configuration would drop the frequency response at 30Hz by about 0.03dB compared to before, and I can live with that. My question is regarding the feedback compensation network (the optional components). Since I've kept the gain pretty much the same, do I need to worry about adjusting/simulating those, or will they likely be ok as they are now (20K + 47p I believe)? Anything else I might need to worry about with this change?