I am looking for a commercial single ended to balanced line out converter or preamp stage. Pre-made units boxed and ready to go don’t seem to be readily available. It seems like a basic thing but not sure why something for say $40 from Behringer or similar doesn’t immediately come up on a search. However, a $10 Sparkfun THAT1646 breakout board with TRS jack did come up. If anyone has suggestions for a commercially made ready to use one, please share here:

Sparkfun THAT1646 breakout board:
https://www.digikey.com/products/en?mpart=BOB-14003&v=1568

Needs a +/-voltage PSU and a panel jack.

I have made simple 2 transistor converters using a CFP in SE Class A and that works well but looking for an ultra low distortion IC implementation here.

I decided to Marie Kondo my lab. I haven't touched tube circuits in years, so my collection of tubes, sockets, high-voltage caps, etc. no longer brings me joy. I think it's time for them to bring someone else joy. 🙂

If you're interested in buying, please toss me a PM or email (add @neurochrome.com to my user ID here). I take payment by credit card directly or by PayPal. Credit card is preferred.

I will use strikethrough and (PENDING) to indicate that a buyer has expressed interest and requested a shipping quote. I will use (SOLD) to indicate when an item has sold.

Unless otherwise noted all tubes are used but not abused.

I will be selling them at the quantities listed.

I'm happy to work out a deal for someone who buys all of it (or all of what's left).

I ship from Calgary, Canada by Canada Post (or DHL if you want it faster and are willing to pay more). I have commercial accounts with both and get a pretty nice discount, which I will pass on to you.
I'll have to quote shipping for each order, but expect shipping to run about $15-20 to the US and $19-25 for the rest of the world (including Canada). If you buy all the iron, the shipping will run a little more.

I'll take $40 (including shipping within North America) for what's left.

--- TUBES ---

• 6AN4 (QTY 5) - $10
• 6AN5 (QTY 4) - $10
• 6080WA, three - $10 (SOLD)
• 6BY5GA, two - $5 (SOLD)
• RTC E188CC, pair - $100 (SOLD)
• Pinnacle 6J5GT, NOS in original boxes, four quads - $25 per quad or $80 for all 16 tubes. (SOLD)
• Electroharmonix 12BH7A, matched pair - $15 (SOLD)
• Sweep tubes: 6GF7A (x3), 6LU8, 6KY8A (x4) - $5 (SOLD)
• Amperex 5842, pair - $30 (SOLD)
• GE 6SN7 side getter, matched pair - $40 (SOLD)
• 7721 (= d3A), quad - $25 (SOLD)
• Sovtek 5AR4, trio, new in box - $30 (SOLD)
• Tube goodie bag: 6AN8, 6AN5, 6BK7B, 6CL6 (x2), 12AT7 (x2), 6BX7 (x2), 6DW4 (x2) - $15 (SOLD)
• Voltage regulator tubes: 0A3, 0B3, 0C3. Boxes are pretty ratty (except the 0C3, which has a nice JAN box) - $5 for all three. (SOLD)

--- MISCELLANEA ---

• STE 8-3 IEC mains inlet filters. Brand new. 115/230 V, 3 A. (QTY 5) - $3 each or $10 for all five. See Post #9 for picture and data sheet.(SOLD)SOLD[/color]
• Sockets: Various 7, 8, 9, and 12 pin ceramic sockets both for chassis and PCB mount. Most are new. Some have been used for prototyping. About 1.5 lb (750 g) in all. - $10 (SOLD)
• Turret strips (as shown) - $5 (SOLD)

--- FREEBEES (WITH ORDER) ---

• 10 uF, 450 V. Bag of about 30. New.(SOLD)SOLD[/color]
• 100 ohm, 1 W, 5 % resistors (QTY 80) - new (SOLD)SOLD[/color]
• 220 uF, 400 V, 105 ºC Panasonic electrolytic. 10 mm snap-in types. (QTY 2) - new. (SOLD)
• 470 uF, 400 V, 105 ºC Nichicon electrolytic caps (QTY 4) - two used, two new (SOLD)
• 47 uF, 500 V, 85 ºC Nichicon electrolytic caps (QTY 6) - used for prototyping (SOLD)

Select your freebee by ordering at least one of my other items and asking for one of the three freebees listed. One freebee per customer.

--- ELECTROLYTIC CAPS ---

• 1000 uF, 50 V, Nichicon Muse KZ (QTY 16) - new - $10 (SOLD)
• 100 uF, 100 V Nichicon Muse KZ (QTY 18) - new - $10 (SOLD)

--- IRON ---

• Antek AS-4T430. Two windings of 0-70-430 V @ 460 mA, two windings of 6.3 V @ 4 A. 400 VA total. Used for prototyping, leads uncut. - $20 - See Post #8 for shipping charges. (SOLD)
• Electra-Print #8037: 70 H, 20 mA plate choke / inductor, (QTY 4) - $60/pair; $100 for all four. Used for prototyping, leads uncut. (SOLD)
• Hammond 156R: 1.5 H, 200 mA inductor, (QTY 1) - $5. Used for prototyping, leads uncut. (SOLD)
• Triad C-14X: 6 H, 200 mA choke / inductor (QTY 1), new in box. - $5 (SOLD)
• Triad FP230-50: 230 VCT @ 50 mA, 12 VA transformer, new in box. - $5 (SOLD)

--- POTENTIOMETERS ---

• ALPS motorized pot, 50 kΩ, audio taper, stereo (QTY 4) - $10/each or $20 for all four (SOLD)

--- FILM CAPACITORS ---

• 47 uF, 630 V Solen polypropylene caps (QTY 4) - two new, two have been used in prototyping, never cut (or even un-bent) the pins - $25/pair or $40 for all four (SOLD)

• 2.2 uF, 630 V Solen polypropylene caps (QTY 4) - two new, two have been used in prototyping, one has cut pins
• 220 nF, 630 V Solen polypropylene caps (QTY 8) - most are new, some have been used for prototyping.
• 100 nF, 630 V, polypropylene Epcos P/N: B32652A6104J (QTY 4) - new
• 0.1 uF, 630 V polyester cap Panasonic ECQ-E6104KF (QTY 30) - new
• 1.0 uF, 630 V polypropylene Epcos P/N: B32674B6105K (QTY 6) - new
• All 52 caps on this list: $10

• (SOLD)

Thank you tubes... 🙂

Tom

Hello everyone, I'm trying to do my first project with DIY Audio. I have found a old radio in the shed, a big wooden box from GDR times.
After checking it it did not seem to work and there are not that many circuit diagrams for that exact model so I figured I would try converting it into a bluetooth speaker (not a portable one but still).
I found this youtube video of someone building a 2.1 bluetooth speaker and thought that I might be able to pull that off: YouTube
I wanted to maybe change it up a little bit as some parts would be easier for me to aquire, the whole voltmeter part would also be left out because it does not fit the aesthetic of the old radio.

I now have some questions for parts and compatibility. I wanted to go for a "Class D" amplifier: TPA3116 2.1 Klasse D Digital Verstarkerplatine Amplifier Board 100W + 2x50W DE | eBay. It has 2x50W and 1x100W output. I also wanted to use crossovers: 2-Stuck V-150 2 Wege Frequenzweiche Crossover Weiche 150W 4-8Ohm 3-3,8kHz 12dB | eBay (sorry that all components are from german ebay).

As I am really completely new to this: first question: would the amplifier and crossovers be able to work in this configuration? Also: what should I look for when looking for drivers for this setup.

My second question for that matter would be how to arrange the insides of the speaker or is that information given in some way in the specifications for a driver. Maybe it isnt really necessary, I dont want to have the utmost high quality sound.

The bluetooth receiver part shouldn't be to hard to pull off. But I would like to add one last thing: a kind of "pre-amp" (?). I don't know the terminology but to describe what I want to achieve: I know that there are adjustable equalizer pre-amps like this: Stereo EQ Equalizer Board 15 Band 2.0 Kanal Vorverstarker Ton verstellbar Preamp | eBay. On the front of the radio are buttons labeled "Bass", "Jazz", "Voice", and so on. This would correspond to some kind of EQ-Setting (for example on a smartphone). My third question is: is there some form of "programmable equalizer" to achieve this change of EQ-settings on button press?

Thanks for any help, I know my questions are pretty broad (at least the second one) but maybe there is a quick answer to that. I don't want to get into creating speakers for eternity (at least for now, maybe this will change), so I really dont want to spend money on a book.

Looking if anyone can tell me what regulators go into U5-U4. 7812-7912? I'm just not sure.

I recently got a pair of Jensen H222 (16ohm) coaxial driver and using them on open baffles. They were designed to crossover at 2000Hz. I want to build a crossover with new component for them. I already experimented disconnecting the old cap and connected a new 3.3uF Clarity Cap (which is what I have on hand) to the tweeter while keeping the woofer connecting to the original coil. It sound better already than with the old cap. Originally, they should have only a 1st order crossover but I can't be 100% certain as they are potted in a small cover.
Someone pointed out that Jensen have equivalent separate woofer and tweeter to the H222 coaxial which use the A204 (2nd order) crossover. The A204 is a 2nd order butterworth as shown in the picture. At first, I was thinking to build my crossover base on the A204. Then I read that Linkwitz has a more flat response so I am leaning more toward the Linkwitz design. I wonder what kind of difference should I hear between the 2 kind of crossover?
Also, if I want to save money on parts; can I use lower quality cap or coil for the parallel connection to the tweeter or woofer so that I can put some better one connecting in series? Or should I keep them all the same?
For the coil, would it be better to go with a smaller gauge foil or a larger gauge wire coil for the same money?

I picked up an "as is" Mesa/Boogie Subway Rocket that was salvaged from a storage unit that had some flooding.

Initial inspection shows really no water damage to speak of. The high water mark is a full foot below the amp chassis so there was no direct water intrusion. Even the speaker survived and even the cabinet is none the worse for wear. I think it got a few inches of water that quickly receded.

However, although the amp ran OK when first tested, which only happened AFTER a teardown and inspection for corrosion issues, (It's very clean, really pristine actually.) after a couple hours of operation it developed an interesting problem. The whole power supply sags badly, and the bias supply sags worst. Normal B+ to the power tubes should be about 460 volts and bias, around 12. After several seconds on, bias drops to about 6 volts and B+ is down around 380.

Note, this happens even with NO tubes in the amp. So it's not a shorted tube.

Since all the capacitors in it are of 1999 vintage by the date codes, it's time for them to go. So I ordered a full set and swapped them all out with fresh caps.

Tests repeated. Results...SAME. With fresh caps.

Basics of the Rocket 44: 4 12AX7 tubes in the preamp stage, 4 EL84/6BQ5 output tubes, 44 watts rated output. Fairly conventional topology.

Subway Rocket is nearly the same amp.

Aside from hot tubes I'm not getting any hot or burning component smells.

So, the question I'm asking and trying to troubleshoot my way to an answer is, what is dragging down the power supply, and the bias supply most of all?

I tend to believe it's not a transformer issue. If it had a bad transformer it shouldn't be coming up to rated voltage at all. Well, if I'm wrong, a new transformer for this model is not expensive.

I have had an amp with a bias power supply problem before that was a bad bias coupling cap, an Orange Drop that shorted after that amp was recapped. The increased voltage from fresh healthy caps killed the Orange Drop so that was replaced, no further problems.

This is kind of a challenge. Usually when I see a problem with high voltage supplies that are being dragged down like this, there's evidence somewhere on the board. Some component(s) are expected to get HOT and be pretty easy to find. This one...not so much.

10x 35Z5-GT vacuum tube, half-wave rectifiers. All used, untested. $20 plus shipping takes the lot.

See:

https://frank.pocnet.net/sheets/093/3/35Z5GT.pdf

12x 6W4-GT vacuum tube damping diodes. $20 plus shipping from 94591 takes all.

See:

https://frank.pocnet.net/sheets/093/6/6W4GT.pdf

9x used, untested 35L6-GT beam power tubes. $20 + shipping from 94591 takes the lot. Local pickup is possible.

Up for grabs are 8 count 'em 8 6AV5 beam power pentodes. All are used, none are tested. I have no sleeves or boxes, but I can wrap in some cardboard for safe shipping. $35 plus shipping from 94591 takes 'em.

I have a dozen 6AU5 pentode beam power tubes. I haven't tested any of them, so sold as-is. Mainly used as horizontal deflection amps, but also use in some power supplies. $35 plus shipping takes 'em. Local pickup possible. Ships from 94591.

I have roughly 39x 6AU6 pentodes, all used and untested. I can throw in about a half a dozen 6AV6's as well. These aren't specifically audio tubes, but they may be fun to play around with. Heck, you could tie 'em together with some string and hang 'em on a Christmas tree (just don't plug 'em in if you do that!)

🙂

Anyway, $30 +shipping from 94591 takes 'em.

Hi,

I really like the sound of full-range speakers and I'm going to build a pair for a friend. His living room is quite large so some bass augmentation is necessary. I've been trying to figure out how to build a FAST speaker using W8-1772 and MCM 55-2421 woofers. I plan to use 2 of these 4 ohm sub drivers in series. My dilemma is should I bi-amp the full range and sub drivers with an active crossover? If I do that the system becomes more complicated, needing two amplifiers, more cabling, etc. I also considered using separate plate amps to simplify things but the plate amps I find are either too powerful (ie PA) or don't have enough power. I'm building the speaker for a friend who isn't technically savvy and likes things really simple. So I want to let him stream from his phone via bluetooth or wifi and avoid burdening him with extra knobs and buttons to fiddle with. The last option in my mind was a passive low crossover and a 2 ch integrated amp to drive both speakers. But passive xo's are totally uncharted territory for me. Any suggestions?

Best,

Selim

I've got roughly 35 3A4 pentode power tubes, all used. I tested a couple and they tested OK. These are relatively low voltage and low power, about 600mW each class A. If anyone wants to experiment, there are plenty here to play with. I haven't got any sleeves for these, so they'll be a hassle to pack and ship. Local pickup is possible. $35 +shipping takes them all. Shipped from 94591.

I've got maybe 10 or 15 6005 / 6AQ5 beam pentode power tubes. I tested one of the 15 tubes and it measured OK, but some of them look like they might be a bit tired. You can get about 10W out of a push-pull pair. I have no sleeves, so I'll have to wrap them in paper towels or something. Bit of a hassle. $25 +shipping takes the lot. Local pickup is possible. Ships from 94591.

Hello all, this is my first post here.

I bought a nice 1952 Browning RJ-12B tuner several years ago, so decided to build an amplifier and make a radio. I started with a power transformer from a Stromberg-Carlson radio, but bought a nice new audio output transformer. The amplifier works and sound nice, but every now and then it will put out a low frequency signal (even with no input) which causes the low frequency speaker cone to move back and forth at what I timed to be 1 or 2 cycles per second. Any suggestions?

Yesterday, I changed the input filter capacitor to 40 MFD, but that did not help.



With the Browning tuner and Renegade speaker I intended to use:


The schematic

I've got about 50 (+/-) 25Z6 tubes, all used, mostly GE's. I tested a couple, and they seem to be OK. Anyone want to experiment with them? They'll be a hassle to pack and ship, as I have no sleeves for them. $50 +shipping takes the lot. Shipped from Vallejo, CA 94591.

Hi all,


I'm looking to buy a few of MJ10014's for testing.
maybe 6 - 10 pieces at most. Don't have a lot of cash but
can pay something reasonable for these old TO-3 type
Darlington chips.


PM me please as I don't check here much.


Cheers,

I have a few gorgeous nos RCA Radiotron/Cunningham # 46 tubes. I have three testers, a Hickok 600a, a Hickok 550X and a Mighty Mite V.

I know how to test a tube of course but the problem is that none of my testers has data for a 46. In fact they don't have data for any of my globes. I need that data to test them but I don't know where to look. I searched but did not find anything.


Thank you

SOLD: Iconic speakers

Now that I have your attention ...

A piece of me died inside today listing these but I am recently an open baffle "convert" and I don't have the room to properly store these. It would be a shame to store either of these speakers anyway!

There is no point typing everything twice and taking up server space with pictures so I will link my FB ads.

1. Snell Type-E/II's in walnut. Sequential SN's, ALL original (disabled rear ambience tweeter) and DIY stands.

2. HIGHLY-modified Klipschorns. Crites cast woofers, Eliptrac tweeter w/B&C DE10s, ALK CSW crossovers, Rosewood veneer

Due to size and weight, I will not ship. Please contact me if you want to audition them.

SOLD

I have an old Peerless/Altec transformer with part of the label missing. The part that is there states it is a Type B-1... Unfortunately the rest of the part number is missing. I've looked through their catalogues from the era I believe it is from (50's) and there is no 'B' prefix letter id to be found.



Any ideas?


I'll try to take some photos in the next few days...

Hi. I'm expert in research & development and repair of electronic switch mode power products. I'm shifting hobbies to acoustics while keeping my profession flexible. It would be great to be part of diyAudio community.

Hi

Do you know where you can buy separate IV board for ES9018/28/38 for opamps?
I want to test some different things without buying expensive boards from twisted pear audio or lcaudio.

Thanks for your inputs.

This is the last item I need to add to my parts order for building an F4, so I need to make a decision between using the universal PSU with Schottky diodes or a bridge rectifier block.

I built my F5 using the diyAudio Universal PSU with Schottky Diodes.

I'm leaning towards the rectifier block as it saves space in a 4U chassis, and the easy of installation.

I just wonder if I'm giving anything up?

Hey everyone,

I was wondering, is it possible to place two speakers magnet to magnet (back to back) using the same enclosure?

So

Speaker 1 is placed on the baffle and its magnet is inside the enclosure, that enclosure is closed off by a panel, in that panel is speaker 2, facing with its magnet to the other speakers magnet.

Is this possible and does it bring any problems with it?
What things should i look for and watch out for?

Ive attached a sketch of the scenario

Anybody had luck building a decent music rendering system out of the Raspberry Pi plus a Wolfson / CirrusLogic Audio Card? My efforts have been a disappointing FAIL.

I'm trying to build a simple media rendering device out of a Raspberry Pi. I know, I know, it may not be the most HiFi solution to the rendering problem, but for this application I'd be content if I could get something up and running that works like a Squeezebox and has passable audio quality for non-critical applications.

The inherent audio system of the RPi (analog output) is well known to be just awful. My experiments were in line with everyone else's in that regard -- the result was lots of cracks, skips and pops. It was a total failure.

Things looked encouraging when Newark Electronics / Element14 in the USA started to co-market the CirrusLogic (formerly Wolfson) Audio Card. I'm in the US, and having a local distributor like Newark / Element14 seemed like it would solve some of the accessibility problems involved in ordering parts from the UK.

The CirrusLogic (Wolfson) card seemed like a decent option, but so far all of my efforts have resulted in failure. I'm wondering if anyone else has gotten the combination to work, and if so, how they've done it.

My first effort was to buy a new Raspberry Pi 2 (quadcore) device and a copy of the latest CirrusLogic Audio Card from Newark/Element14.

When I bought the CirrusLogic card, Element14 was marketing it as being compatible with the RPi 2, but they stopped advertising it as being RPi-2 compatible when it became evident that it was only pin-compatible as a plug-on card, and was not software compatible.

The problem, as discussed on the Element14 site, is that CirrusLogic still hasn't done their job of writing the ARM-7 compatible drivers for the quadcore RPi-2. At this point in time, the software support for the hardware on RPi-2 remains vaporware, which has resulted in quite a few disgruntled customers.

Community: Cirrus Logic Audio Card | element14

My second effort was to fall back to installing the CirrusLogic Audio Card on a Raspberry Pi B+.

Since the audio card wouldn't work with the ARM-7 quadcore RPi-2, I decided to use the ARM-6 RPi B+ as a fall-back option. Element14 is still advertising these products as being compatible. Unfortunately, my efforts to get the card up and running on the single-core RPi B+ haven't fared much better:

With the B+ I've found it impossible to build the kernel drivers, largely due to the fact that the manufacturer's wiki article is poorly written and contains enough errors to force the effort to result in a FAIL.

Has anybody had luck in getting the Wolfson or the CirrusLogic Audio Cards to work as a rendering device on the Raspberry Pi? I'm having a bear of a time getting the hardware/software to work, and I'd really like to know if anyone has been successful in doing it.

If you have been successful, please let me know whether you've been happy with the quality of the audio output and the usefulness of the device as a music renderer. I'm hoping to find out if it's possible to succeed in the task that I'm trying to accomplish, whether the functionality and sound quality are worth the additional time and effort that's going to be required to get it to work, or if I should just fall back and punt.

TIA.

Can anybody help with information, schematics etc.
of thr ARC MCP33. This unit is an MC Prepreamp.

Reinhard

My two year old z906 controller and/ or powered sub has failed. How can I use the existing speakers and maybe the sub-woofer? Can I power the sub with something or make it passive? Hate to throw out all this equipment. Any suggestions with brand name and model would work. Thanks

I'm working on a 2-way system using a stack of 4 5" woofers in a 50L box. My initial choice for the drivers was poor, and I've given up trying to get them to work. They have an aluminum cone and sound like a pie plate. I'm using the miniDSP-HD in an active crossover system and have tried all manner of EQ.

I have my eye on the Silver Flute W14RC25-08 as a low cost option and the SB Acoustics SB15NRX30-8. I like the low VC inductance of the latter, but it is pricey.

I've also just come across many Peerless options; maybe the TPY05W08O0088, Heritage.

I'm looking for any comments on these specific drivers or any other suggestions.

Thanks,

Chris

I built a kit from Madisound, which most importantly came with 'prefect' CNC cut panels which allowed for easy (and perfect) assembly. At $130/cabinet (before discounts for the kit), it seemed obvious they did a big run and were able to get some efficiencies.

Is it common to get plans and have a shop CNC cut material of your choosing for just one single pair?

I think it is less an issue of a shop that 'can' do it vs. one that will do it for anything approaching a reasonable cost. For a modest pair of small towers, I imagine you will pay a bare minimum of $200 on top of the materials. Further, if you brought them a design, it would need to be translated into a file the CNC machine could use (so maybe minimum of an hour of billable labor on top of the actual build time)?

To be clear, only talking about getting the pieces cut, not an assembled cabinet.

Hi,

I would like to buy an Altec Valencia single cabinet without drivers.

Please no suggestions to build one. Thank you.

Cheers,

Horacio

Hi,

I have this TPA3116 board. Why are the speaker outputs both at 12V relative to the ground input? I've done some gain and input circuit mods but this isn't normal? Running it at 24V with a switching power supply. Otherwise it works well but just noticed this. The + and - speaker outputs are mV as you would expect, but both +12 relative to ground and input voltage!

any ideas??

Thanks,

Thei

HI

I HAVE A POWER AMPLIFIER HERTZ HP1D AND I HAVE A PROBLEM WITH PCB
DWM3640 DRIVER LOW-HIGH FET
------------
THE LETTERS ARE RESPECTED BY THEM(IC DRIVERS U1 U2 U3 U4)
DOES HE KNOW THE DATA FROM THESE

THANKS
NSTR

Hello from Poland. I have damaged amp, unfortunately someone was already doing something in it. Cut paths from security etc. I want to bring it to its original state. Does anyone have any service documentation? I would be very grateful. Regards

Current system: Akitika PR-102 preamp and GT-102 power amp with Bose Interaudio 4000 speakers. I'm currently considering 3 sets of speakers for my next upgrade, and would like to know if driving any of these with the Akitikas would be asking for trouble. Also if one jumps out as a much better fit than the others, since I won't be able to hear the last two before making a purchase.

Option 1: A pair of nicely reconditioned JBL L100 speakers from a friend. They were put in nice wood cabinets about a year ago and got everything that needs to be replaced over time upgraded, so they sound better than new. They'll be about $2500 plus 5 hours in the car with the friends and family discount.

Option 2: A pair of Polk LSiM707 since it's that time of the year for Polk's half off sale. After tax (grrrr) that'll be about $2150 for the pair. This seems to be the most questionable for whether or not the Akitika will drive it. I seem to remember reading that these needed a beefy class D amp somewhere, but I could be thinking of something else.

Option 3: Save some more money and get a really pretty Seas Odin pair as pictured on Madisound instead of one of these. Seas Odin Speaker Kit - PAIR

My Parasound HCA806 has at least 3 bad channels. The symptom is a heavily distorted sound.

I have done quite a lot of basic electronics repair over the years so I'd like to try my hand at fixing it. I have a few questions:

1) It seems like the capacitors are the common problem in old solid state amps. Should I just go ahead and replace them in one of the bad channels as a first step? What model of capacitor should I buy?

2) I couldn't find schematics for this one, but I have them for the 800 and 855. Is anyone here familiar enough with Parasound to know if these will be helpful (or even better, does anyone here have the 806 service manual or schematics)?

3) Should I let the amp sit for awhile before opening it up? I have read that if you're not careful, amplifiers can discharge quite a lot of electrons even when they are unplugged.


Thanks!
Mark

Hi


Does anyone know what is the bias setting for this amp. There are 3 trim pots, VR4,VR5 and VR6 on each power amp board, no information is given on the schematic on the bias settings. I guess that VR6 is for biasing and VR4 and VR5 for DC offset. I have replaced some blown power transistors on each channel. I did not rebias after replacing the transistors, but using the preset bias. After leaving the amp ON for 2hrs, the left channel feels warm but the right channel is hot. Please assist. Schematic attached.


Thanks

Hi everyone -

just finished connecting everything up on my f5, softboard works, dc protection works, psu work, one channel works, the last board put in - R7, R8 and R14 burned. Needless to say, gutted and confused. Any idea?

thank you

Philip

Hi Friends,

I am an Indian Resident. As we all know that agter COVID-19, World is changing rapidly and this might lead to averting of purchaser countries to import from China. This will definitely be an opportunity for some other country to begin manufacturing facility.

I am just creating this thread to access effect of this polorization.

Hi All

Did buy these old bose 301, getting start to restaurate, woofers need to be refoamed, old one is complete gone.

These do sound nice, I did always like them, from 1975 so very old.

Like the good old days, better for environment.

regards

Hi, I got my hand on cheap B&W sub that plays pretty nice bass but when played out loud or for long time, it turns itself off. After letting it cool down and turning it back up it plays like nothing happened.

I guess its overheating because thermal connection between parts and heatsinks are bad after all those years of usage. But I am no amplifier expert, I know my basics, can build stuff from kits and so. So just to be sure - is there any other reason for class D amp to turn itself off other than heat?

Thanks to you all kind people

While I'm waiting for my transformers to come in, I thought I would give LTSpice another shot and play around with some values. I had some trouble with the 12AX7 model in the past, but worked it out. Now I'm trying a KT88 and I'm not really sure what I'm looking at here.



Basically I am getting -223KV on the grid. I played around with different values(which is why some of them might seem wacky) to try to get the grid to "move" to see why it's doing this. I detached the signal just in case it was coming from that somehow(impossible with the cap).

Is there something obviously wrong with my schematic or is my KT88 model borked? Someone else on this board had a similar problem, which they fixed by renaming the symbol's pins to match the model. This did not seem to help.

Hi,


I just bought a second hand AudioStatic ES-100 print. It has 2 wires for power supply connection, but I'm not sure what voltage to connect. Can I connect it straight to the mains (220V, Europe), or is it a lower voltage like 12 V? When watching photos, I see just a wire from the rear of the ES-100, but I've read about 120 / 12 V power supplies for the ES-100 on this forum. I wasn't able to find a schematic of the ES-100, only for the ES-100, where a 9V voltage input is printed.


Kind regards, Jeroen

any suggestions ?
thank you

I apologize if I have overlooked it, but I couldn't find measurements of the Cubo Kick 15 design anywhere, so I thought I'd post them here.

The bin has been built according to the available plans on freespeakerplans.com, but with 18mm poplar multiplex, which was on hand. This makes it VERY light, but it needs some more reinforcements (which we still have to implement). It is loaded with the 18 Sound 15ND930, 8 ohms.

Measurement is with 2.83V at 1m, mic on the ground, measured outside, 2pi.

THD seems a little high 😱. We'll reinforce the cab and do some more measurements.

Working on my second simple pp! The first one was set up in triode mode and this one will have pentode outputs with a regulated screen supply.

I am thinking a pair of stacked glowtubes would suffice for a screen supply and look pretty...

The outputs are a pair from stancor out of a Heathkit AA-100 that are 7kpp with 0-4-8-16 secondaries.

Its coming along...

4 x Salas Reflektor-D assembled with Tea Bag kits. Leftovers from kits included.

2 x 3.3V & 2 x 5V. Output voltage easily changed.

40 GBP each plus postage.

Good day
Currently i have pretty good modern hybrid system with radian 950+k402 on top and bass reflex low section.
But i`m going to grow a bit)
I`d like to try something like western electric 555 driver + we15 horn, but originals are too expensive for me and i`m a bit scared of 5 watt maximum power handling.
Horns aren`t a problem because there are people in my country (Ukraine) that are making we15 clones for much cheaper. The main difficulty are drivers.
I am looking at clones like lamar audio and G.I.P.( don`t know more, maybe you can recommend other).
And i have a few questions:
1)Maybe someone was able to hear them and can tell me how do they compare with original we555 and more modern drivers?
2)If someone used such a deep horn, how did you manage with time delay between woofer and driver?
3)I have read Geddes and many other literature about horns and all of them share the same opinion that such a long horn can`t sound good. Is it true? I have no possibility to listen them, aren`t they just a cool vintage stuff that sounds bad?
Would be very grateful for any thoughts of more experienced colleagues

I shot an email to Dan at Akitika and told me that you "can't" have balanced input/output on the PR-102 or balanced input on the GT-102, but didn't get anything back when I asked why not. Does "can't" mean he doesn't want to mess with and/or support it, or is there some design limitation that prevents anything other than RCA from being used?



In principle it sounds doable. Remove the RCA jacks, drill a bigger hole (probably limited to one input and output on the preamp due to the proximity of the jacks) and drop in the new XLR. Am I oversimplifying and missing something obvious? I ended up getting the preamp and power amp second hand so I didn't do the builds on these.



Sooo...XLR on Akitika. Anyone actually done it and can confirm that's it's possible? 🙂

RIP, a very well respected tube designer, audio engineer and contributor to BAF:

A tribute is here:
Electra-Fidelity

Best,
Anand.

I need to get a pair of Quad II working for a friend. He has 3 working old KT66 but doesn't want to pay silly money for a fourth.

What other output tubes do you suggest? I have 5881 and EL39 for example - may also have some EL34. EL39 have top caps, but that's OK - nice tube!

Hello,


I'm just starting to read Bob Cordell's book, I was wondering where is the right place to ask questions about is book? Bob wrote : "output impedance will be increased if smaller values for R2 and R3 are used", Why?

Hi Guys,
Can anyone recommend a budget friendly (if there is such a thing) Amplifier and pre-amp for Alon IV. I dont mind a DIY if need be.

Hi,

As the title says I am selling 6pcbs(3 of each kind).
Both pcbs, the dual and the bipolar are the same dimmensions and have the same mouting holes.

Some details about them
102.54mm * 251.44mm ;
Layers: 2;
PCB Thickness: 1.6mm;
PCB Color: Green;
Surface Finish: Hasl;
Copper Weight: 1;

The boards are designed to be used with avel lindberg 50VA incapsulated transformers.
Transformer input is configured only for 240Vac input.

The dual lt3081 pcb has 2x lt3081 each one connected to a secondary winding of the transformer, completely independent between them.
The bipolar lt3081/lt3091 pcb has one piece of each reg and these are connected each one to a secondary winding of the transformer thus isolated between them also.

I will describe in short what is on the pcbs.
We have ac line in, fuse, transformer primary.Since I have opted for screened transformers I have connected the transformers screen to ac earth as suggested by avel lindberg.
After the transformer I have c rc network to eliminate rectifier diode ringing.I can supply the values of the components for these networks for the 50va 2x20V and 50va 2x12V transformers.
Next are the rectifier diodes, after them a crc filter and finally the lt's.
For the lt's I have included a 1206 smd resistor to setup output voltage, or you can use a pot which has also it's own place on the board.

In the first photo you can see the bipolar pcb. If you look on the bottom you will see the outputs which are signed as out_pos and out_neg.
Second photo is the bipolar pcb bottom.
Third photo is the dual ps pcb.
Fourth photo is the dual pcb bottom.
Fifth photo shows the bipolar ps front side.
Sixth photo shows the dual ps powering a b3se dac and cronus reclocker.
Seventh photo show the back of the bipolar ps.
Eighth photo shows bottom of the bipolar ps.
Nineth photo shows the bipolar ps near a legto iv stage which was powering with succes.

All boards are sold


Thanks.

With no output fets the rail voltage is 48v where the 640's are and 52v where the 9640's go. When I put the fets in I have 100v where the 640's go and 0 where the 9640's go. Any ideas why this is happening?

HYPEX NC252 MP NCORE POWER AMPLIFIER.LESS THAN TWO MONTHS OLD.IN LOVELY CASE.FANTASTIC SOUND AND BIG SAVING OVER NORD OR APPOLLON. £400 PLUS POSTAGE.UK SALE ONLY.

Anyone have a pictures of the output section?

As a "thought experiment", some musings, trying to design a super high efficient two-way. The two culprits are the Audio Nirvana 15" classic ferrite, and the Aurum Cantus G3...
By plotting the two together, my best guess is a first order for the AN 15 at about 2K, so by 4K it has tamed that rising response, dragging down that hot spot 6Dbs worth...what do you guys think?





----------------------------------------------------------------------Rick........

Let me know what you can spare!

Jack

Hi Gentlemen,
I am delighted with my just finished Alpair 10P speakers. I have built several smaller full rangers using Tang band 4 inch drivers in the past and liked them pretty well, but the Alpairs are in a whole different league. I would like to turn a couple of friends on to this full range experience, but dont want to spend more than necessary on the builds since I'll be gifting them.
A while back forum resident XRK, who is very knowledgeable, suggested that on a super low budget the Dayton Audio PA 130 would work well for the price. I built a pair, and while they were not bad they had little to none of the "magic" I hear in the 10Ps.
So, are there any full rangers that approach the bass depth, detail, and SPL levels of the 10Ps for a significantly lower price? I think I'm asking for a lot here but am hoping that there are some hidden gems out there.

Best,
Jay

This summer I will buy myself a record cleaner machine. My records have never been cleaned, so I have been looking at The Nitty Gritty Recordmaster 1 and Pro-ject VC-E or VC-S2. Which one of these do You think are the best?

I have no idea if anybody has posted this before but if anybody has the time and patience its not too hard to build .


Keep in mind this is a "proper " tube tester in that it employs a Wein bridge oscillator to test the tube .


The circuit is available in issues of ETI magazine -


Volume 26-number 8 and volume 26- number 10.


It can be accessed on that wonderful American radio heritage website -




RADIO and BROADCAST HISTORY library with thousands of books and magazines

I've only found frequency (182-400hz) but no others informations (modulation...) in order to recreate the typical sound of emergency vehicules.

Any clues ?

More than 5Kw output and less than 0.09% distortion from 20 hz to 20 khz, good for low freq. and lower mid as distortion less than 0.037%at up to 1khz, Load showing more than 10 kw at 0.5 ohm, more than 5 kw at 1ohm load, with 28 pair in output will deliver more than 5 KW.continuous . Designed by Vedmitra.

Good evening all,

I am experimenting with a Frankenstein re-build of an old pro-sound subwoofer. The only voice coil I could find so far is from the car audio world, and is rated at a disturbing 1 ohms nominal impedance.

Do any of you know of a module or proven design which is stable at such a load? I thought of using a car audio amplifier, but it seems a shame to step the mains voltage down to 13.5 or whatever, only to have the power supply in the mobile amp step it back up. North of 500 watts RMS if possible!

Thanks for your help,

JF

Hello,

I'm using this site for rapid crossover simulation of two raw drivers : Speaker Crossover Calculators by V-Cap I like the possibiity to enter the impedance of the high pass and low pass for each driver.

I please have a question about these two impedance : should it be the impedance of each standalone at the precise cut-off frequency or the average Re (voice coil resistance) given in the datasheet... Or the lowest impedance point where the impedance curves meet each others in frequency ? I.E : the impedance at cut-off of the weakest Z of the two drivers cause this is what see first an amp!

Just for illustration : 2 bass driver, 2x 8 ohms with a Re of 7.8 ohms , chosen cut-off : 300 hz, here the impedance of the two // drivers measured raw is not half of the 7.8, i.e 3.9 ohms but 3.4 ohms.
The mid driver ha a Re of 7 ohms and at 300 hz the impedance curve is 6.5 ohms.


Sould I putt in the calculator at 300 hz : low pass : 3.4 ohms and high-pass:6.5 ohms or should I simply enter the average Re of each drivers given in the data sheet : 7.8/2 for the 2 bass : 3.9 ohms and 7 ohms for the high pass for the mid driver ? Or I enter the lowest impedance for the high and low pass cause electicaly this is where it goes : 3.4 ohms


The question is for passive XO but I ask for active crossover as well : has the exact impedance at Xo cut-off to be entered in the soft parameters as well or just the average Re of the drivers.


Many thanks.

Hi this is my first post in this forum. I am trying to restore a pair of German made ALR Nummer 4 speakers which I picked used. There is a crossover board inside which for the midrange and the tweeter and a separate board for two woofers. On the mid-tweeter board, there are two components which looks like resistors but had 47RJ written on them. They are as big as a 3W resistor. are these resistors or 4.7uH inductors ?? How can I find it? I replaced them first with 3W carbonresistors and sound became very shouty which is not at all close to the working pair I have. But when I used a 0.82ohm small 0.25W resistor it sounds close to the good speaker which made me think this was an inductor more than a resistor.

What is the difference between wirewound resistor with value 4R7 and inductor 4R7?

When we're talking about active crossovers, setting the gain is pretty straightforward when we're talking mid-to-high frequencies; just give the stereo channels a flat response. But I have a question about what happens when you have a mono sub. Do you make it so that the sensitivity of the mono channel is (up to) 6 dB higher because there is only a single channel, or match the sensitivity with the stereo channels because the summed signal will automatically be at a higher voltage and result in the appropriate higher SPL? I'm leaning toward the latter but would like to hear others' opinions/facts.

...
Such a thing ?
I would like an oscilloscope that works like old fashioned CRT type ,
but with solid state display .
There used to be plans for making an oscilloscope from a T.V.
Is there now an analog circuit that will drive ????? HDMI monitor ?

In fear of too much bass in my room I changed my mind and want to build the CGR Mar-Ken instead of the Pensil for the 10.3. My old (2005) Seas 21cm bass was too deep & mighty for my room.
I think the CGR Mar-Ken or BR will show more 3D/soundstage and detail than the Pensil.
The question is: Can I transfer the vent to the back? I cant see any problem doing that....or?
Thanks in advance.

Good day to all
Finally i have bought all drivers and horns for my system so i can start building theme
Here is the list what i have:
HF- faital HF10AK+ STH100 HORN
MID- Radian 950 + klipsch k402 horn
LF- faital 15pr400
I will use passive crossover, targets are 600hz@12db and 6000@6db
Autotransformers will be used instead of l-pads, maybe i’ll go with active crossover someday
I have a few questions :
1) displacement between radian and woofer will be about 40cm
If i will put drivers and woofers in phase, will I hear time delay?
I found passive crossover time delay scheme but it is very difficult
2) what is the best placement for HF10ak?( maybe in LF- section?)
Also i’m considering about making fronthorn enclosure like in tad 2301 to minimize drivers distance
Thanks in advance
With best regards, Andrew

Say we have a pair of beam tetrodes that need a load impedance of 8K plate to plate. Then we decide to put the centre tapped output tranny in the cathode circuit instead. Would the right load still be 8K? Obviously the circuit would have a lower output impedance, but it can still only pull the same peak current as before, so what's the go with selecting the right load?

Hello,

Would any of you be so kind as to point me to some info/schematics about the old C-Audio RA501? I've recently purchased one of them, and it ha intermittent errors on one channel. After taking into account the low level of local audio techs, I'd rather provide them at least with schematics.

Thanks in advance for any possible help?

Cheers,
Mihai Toma

Hi,
I have this amplifier but it has a problem now with DC on speaker output.
When i turn voulume up i see with my voltmeter there is DC voltage on outputterminals.At 40% volume i hear rele clicks and DC drops to zero.
Is amplifier totally damaged or is it the preamppart.
I need a servicemanual to find out were DC occurs in signal.
Any good advice?

Thanks,

Dear Folks,

Does anyone do this 6N3 based preamp can share the schematic ? My friend give me 4 these tubes. I want to DIY the preamp and use in between the DAC and Power AMP (FET)


CK

All,

I have designed an SPDIF to I2S converter based on the CS8416 in hardware mode.

It supports up to 24 bit / 192kHz, while automatically adjusting to all standard sample rates and 16 / 24bit operation.

It can come in two varieties:
1. It can be powered from 17 to 72V and provide an auxiliary PS with 12V 800mA output.
2. In can be powered from 6 to 28V and provide no auxiliary PS.

The board also has a feature to bypass the I2S from CS8416 with an external I2S bus. When SPDIF is not present the secondary I2S bus is routed to the output.

Prices as follows
$200 if 10 people purchase with 14-72V input
$150 if 20 people purchase with 14-72V input
$130 if 30 people purchase with 14-72V input

$170 if 10 people purchase with 6-28V input
$120 if 20 people purchase with 6-28V input
$110 if 30 people purchase with 6-28V input

PCBs are high quality 2 layer boards with ENIG finish and use only high-quality components. Boards are manufactured and assembled in Canada.

See attachments for board sizes and pictures. Dimensions in mm.

Thanks for your time.

Leo

I am looking for high excursion aluminium diaphragm woofers with inverted surround to efficiently reproduce low frequencies in small volume. I'm not looking for woofers with other diaphragm material or surround taller than basket.

Peerless SBS160F35AL model is not available for retail purchase.



Any other ideas?

Refurbishing a pair of speakers and need fast tight bass in a 6.5” to 7” woofer

any learned advice valued and appreciated

Thanks,

Martin