A family member asked me if they can play their TV audio over the hifi. Sure - that’s easy with an interconnect cable from the TV audio out headphone jack to the line-in RCA on the Marantz amp, right? Only caveat – this cable needs to be 15 meters (about 50 feet) long if routed to satisfy WAF. Is this feasible at all and what kind of cable do I use?

Hi, I’m building a pair of floor-standing speakers. The height is about 120 cm. Width 29 cm. And depth 36 cm. At first, I planned to use the 20 mm. MDF as the cabinet walls and 1-inch thick MDF for bracings inside the cabinet, as seen in some commercial speakers. I went to my local carpenter shop, he usually build car speaker enclosures, and had him build my speaker cabinets. Unfortunately, he used wrong thickness on my pair. He used 12 mm. MDF totally, the bracing construction and dimension are correct every point though. He offered me discount for these cabinets due to his mistake. I’m now hesitate whether I should accept his offer or not. Could anyone please tell me what is the result of using thin cabinet wall? What way will the sound go and affect? I’d like to know if the sound is distorted, how? Bass boom, Midrange echo, etc. Please explain me. Thank you in advance.

Dear All Aspenites,
It may have fallen under your radar but the Aussie Dollar has now firmly entrenched itself at under 70 cents US. This is a great time for all to update those older Aksa's, Naksa's and Lifeforce's to new Saksa's and Maya's. This is a great opportunity! Now is the time to move up to better music enjoyment!!!

Which is the formula to calculate the gain of an input-driver stage (i.e. 6C45P driving 300B) with a choke-load and with a resistor-load ?

I want a Linux based music player that does this, after I execute the playback.

1. Decode and store the full music to RAM.

2. Communicate sampling rate, bit depth etc to usb dac via usb audio class 2 protocol, and if possible do a short sync.

2. Remove all handles (no scrubbing, no seeking etc) except play, stop and pause with keyboard interrupts. Probably even remove mouse/trackpad polling, and stick only to keyboard.

3. Play the song.

4. Have option to change volume alone (communicating volume to dac directly through usb audio class, not software volume control) when needed, again through keyboard interrupts.

Make sure that it is very focused and instruction sequences are fully about music playback and music playback only, by starting and incrementing memory (instead of checking for user input on location everytime, stealing instruction cycles).

I recently tried hysolid on windows and I was blown away. It has its control done via a smartphone app, using wifi but the concept is the same with respect to playback. The sound is a serious improvement over other players I've tried (difference is higher than moving between multiple class of headphones). I'd prefer if it ran on 64 bit engine, which imo is the only improvement I see missing in hysolid (other than it being windows exclusive and having to put up with other daemons in windows).

I tried ap-linux yesterday, and wasn't satisfied. The installation procedure, for a Linux noob like me was super hard and a friend guided me through it for hours together. After installing i found that it had 3 players - deadbeef, audacious and cantata, with a realtime kernel on the system. I don't think it felt in any way better than winyl on windows and a far cry from hysolid.

Since it was too buggy to try around, I've removed and I'm installing gentooplayer by the recommendation of a friend. Would like guidance on the music player setup as per requirements above. I saw that it allows to have ramdisk to store the music but I am unsure if the playback engine works the way I described above.

I also tried to experiment with daphile but again I encountered issues with network connectivity etc (surface book doesn't have ethernet and it's wifi chip seems complicated, and bad imo).

I am open to experimenting with other distros - my laptop is surface book. I need to dual boot, and can't compromise windows. I am less interested in remote control, though I am okay with it if there's no other way. I want to use windows for other purposes, and Linux when I want to jam out with music.

I have a couple of old Hammond 12S200 chokes. They’re swinging chokes with a rating of 4 – 21 henries @ 200 ma and with a peak voltage of 5K. Would it be safe to assume that they could used in a circuit of up to, say 400 ma, with a significantly lower voltage?

I am having trouble getting my Almarro 318B to bias down to the correct 200mv range. I have put in new power tubes on a couple of occasions and it seems that within 2-3 weeks, the tubes start to run hot. I am already biasing at the minimum. Is the a symptom of a problem that needs fixing?

The problem seems to have gotten worse over the years. I have tried all the NOS Sovteks out there from the late 60s to early 80s.

I am going to bring the amp into a local amp repair technician but want to give him a start on the problem.

Thanks.
Dave

I have a bluetooth player I picked up off Ebay. Its basically a receiver/USB player with a sealed sound box, two speakers, one on each end. Its been made to look into a faux gramophone, which looks pretty cool. It also has a round resonance "flapper" on the bottom, which adds bass. That is not really a speaker, it just vibrates.

The whole sound scheme is pretty good. However, I was disappointed to find that the horn on top, is basically dead weight and no sound comes out of it. Its just screwed into the back of the box, with no opening through to the box at all.

I know enough about acoustics to realize that a sound box needs to be sealed, etc. For example, when you unscrew the top lid and take it off, practically all the bass is lost.

So here was my idea.
I'd like to buy one of these 1" tweeters, and stick it in the mouth of the horn. Then run a wire, through the sound box, to the reciever:

1-INCH 260W MAX POWER SILK DOME NEODYMIUM TWEETERS - PAIR | eBay

The sound box would still be sealed, just a small hole for the wire down through the horn, which could be closed with silicone. That way the horn would actually work, and in theory, it would improve the overall sound.

Would doing this however, reduce power to the existing side speakers, make them quieter? Is this idea doable, or just a waste of time. Thought I'd get opinions...... thanks

Hello. I just moved, and now have a small workshop, I can use for my speaker building. Because it is small, I need to come up with some really neat ideas for a multi use work table / table saw, etc table. I see the table top probably being in the 4 ft x 6 ft range. This table will need to be on lockable rollers, where I can maneuver around it easily. I'm thinking I may run an electrical line above head, with a power strip up there, and make all of the power cords come down from above. I can see the need to be smart about utilizing the under side to build a low shelf the same size as the table's top. This allows mucho storage for clamps and power tools.

Any and all suggestions are welcome ! And thank you.

Hi,
I looking for A mid-quality RCA cables.
I only asweming that thickness and the head quality is important.
Up to 50$ for 2 cables (or 25$ for 1 🙂)
AMAZON & eBay is prefered
Thank you very much!

Looking at the variety of commercially marketed active subwoofers from all the manufacturers, it is quite apparent that most of them shrink the box down to the smallest practical size. A typical unit might use a 12 inch driver in a 40 liter sealed box. Through the use of equalization, the resulting sub has (or is claimed to have) a response down to 20 Hz.

Are there any practical guidelines on how much equalization can be tolerated before sound quality degrades? Are there other considerations or trade-offs to shrinking a subwoofer box down to well-below optimum size?

As an example, the SB Acoustics SB34NRX75-6 12" woofer would seem to work well in a 100 liter sealed box (Fs=19 Hz, Qts=0.4, Vas=260, Xmax 0-peak= 11mm). If this box were shrunk down to 50 liters, the resulting system would need a boost of about 6 dB at 25 Hz and a cut of 1 dB at 70 Hz to match the optimal 100 liter box. What are the down sides to shrinking the box and doing the equalization (other than the need for DSP and plenty of power)?

Thank you for your thoughts

I have a Stetsom 10.5k amplifier that came into my shop with some shorted
output mosfets. I replaced the mosfets on both sides and the gate driver ICs
on both sides and the logic gate ICs on both sides. I also replaced the gate
resistors that were out of spec and few of the diodes around the output
mosfets were replaced due to shorting.

When I feed the amplifier 14.5 volts the amp gives me an undervolt error. I
replaced the diodes in the undervolt circuit and replaced Q27 with a BC817.
I also checked the resistors and capacitors in the circuit and they all
checked good.

I removed R127 and jumpered pin 8 to pin 14 and started the amp up and now I
get an overvolt error. I was wondering if anyone could offer suggestions as to what may be the issue.

The power supply never tries to boot up. The amp goes straight into
protection. No rail voltage is being produced.

The amp has a 14 pin PIC16 chip. These are the pin voltages before I installed the jumper.

1. 4.97
2. Crystal
3. Crystal
4. 4.11
5. .005
6. 4.70
7. .002
8. .005
9. .002
10. .003
11. 4.64
12. .010
13. 5.60
14. .003

I am including a photo of the area in question.

Thanks,
David

Hi Everyone , does anyone have any experience with any Zenith 12 inch Speakers?

Does anybody have a 12-Pin compactron tube socket pattern for Diptrace that they wouldn't mind sharing? Thanks.

I bought the LXmini kit a couple of years ago and I am not going to get around to building the speakers. So, I have the kit and some extras (like pvc pipe, the large rubber things at the top, and more). Some of these things I wouldn't ship.

My first attempt at moving this kit to someone who will give it the attention it deserves would be to find someone in the Philadelphia area who wants the kit and the extras. BTW, my zip code is 19075. You can see generally where I live.

If you are interested please PM me and we can discuss everything I am offering. And I should add that I do not have the wood pieces. I have the basic driver kit and some other things.

Hi:

I am in the process of restoring a GAS Son of Ampzilla amplifier. The original non functioning VU meters and the rudimentary meter circuit is being replaced by newer meters and an independent IC based driver board.

For the driver board and VU meter lamps I need a 12V supply; the driver board can work with either DC or AC for which I need a separate transformer or power supply.

The challenge is that the space inside is very limited. Can anyone recommend a small size 12V power supply or transformer. I believe the current requirement should not be greater than 400mA. Alternately, could I tap 12V from the +/- 51V and +/- 45V rail voltages?

Thanks
Mayank

I started work on the bookshelf speaker for a friend. Now this is something special, I can't stop listening to this speaker. Phenomenal coherency.
Anyway, I got G2 ribbons from nice diy fellow here, I got betsy wow from 'd to the g', and placed betsy wow in closed box (ikea bookshelf).
I removed the dust cap, installed brass phase plugs and coated the cone with the 'wet look' from parts express.
Measured the response, I can post it later, it was gently rising, minor breakups, rolls off at ~10kHz. I applied the bsc (0.5mH, 10 ohm) to flatten the response. Measured again, added ribbon, settled on 2uF cap. Nothing more. Flat fr response, flat phase (i tested in and out of phase). I listened with and without sub, sub is optional, depends on personal preference.
Anyway, I build betsy and ribbon before (old thread somewhere), this approach works. This time result is even better.
You got to hear it to believe it.

Gentlemen,


I posted a message a while back for a "simple to build" enclosure for the Fostex FE 206 ES-R.

From this post, I received a lot of good advice from Scottmoose for building a BIB -TQWT. He even did the calculations for me (thanks again BTW). So everything was ready to R&R.

So I was all ready to go, except that I discounted the WAF in my plans : my future ex-wife threw a serious tantrum when she look at my plans and discovered that these beautiful boxes would be over 2 meter tall...

Not planning to move out of the house in the near future and be forced to sleep in my car, what recommendations would you have for an enclosure taking care of the Wife Acceptance Factor.

1) Fostex recommended enclosure for the FE 206 ES-R ? as per the attached file.

2) A Nagaoka D58-ES ?

3) Others ??

Thanks,
Sierra

Hi!

So a few months back I got an old Ahuja HRC-32T tube amp with 2 EL84s in class AB and the seller told me that it has 3 ECC83 (12AX7) in it.

Well, the labels have come off and 2 of them seem similar while the other one looks a bit different.

Can anyone help identify these tubes? If they are 12AX7 or not and the manufacturer.

The 2 similar ones have filament flash, their plates are shorter than the other one, and they have circular (not oval) holes on each sides of the plates while the other one has no holes. Also, the 2 similar tubes are a tiny bit (1-2mm) shorter than the other one, but that could just be a tolerance thing.

I have attached the pictures of the tubes down below.

Thanks everyone!








P.S. Sorry about the upside down pictures. They were fine on my phone, don't know what happened.

Just thinking out loud....

Ive seen good stuff written about this little Russian D.H. Tube wired as triode...

I'm wondering how it would be to use as a gain-stage rather than driver/O/P stage, maybe with MOSFET on top....

Any thoughts....?😉

I came by pure luck on a web site written by Kurt van Lilienthal Heitmann Thaaning Steffensen. A large collection of 100 amplifiers schematics and descriptions, starting from "The Audion by Lee DeForest, 1907", until "Luxman MQ-50, 6550 PP, Stereo, 1983". I'm not qualified enough to estimate the quality of the analysis but from what I read the author seems to knows his business.

• Lilienthal Engineering | Valve Amplifiers, Tube Amplifiers, HiFi, Recording Studio, Guitar

Some gems in there :

• EL6471 is a typical example of such amplifier. It is a class B power amplifier rated at 1000 Watts and it runs at about 3200 Volts. The weight of this monster is 155 kg.
• Altec 260A, 813 PP 1956, now, we are talking…Look at this at this thing…1,2V RMS at the input terminals and you will have some 260 freaky ALTEC Watts to feed your speaker !

Enjoy while you are locked down 😉

For sale, Original style Magnequst EXO-173 transformers, these are "pinstriped" unts (M6 and nickel)... and are housed in solid brass channel frames. They are a 4 terminal autoformer. They can be used in several different ways. They can be arranged as a 1:2 step up and as a 2:1 step down transformer. EXO-173 can not carry any DC Current.
I have two pairs for sale,
My price is $140.00 a pair plus shipping(Both pairs Sold)

Hi All,

A while back a kind gentleman (Matt Garman) sent me one of Richards PHIDac kits. After much torture soldering ant sized SMD components I think that I'm ready to power it up and give it a try. At first I'm going to try feeding it I2S from an old ministreamer that I have. I do have one question about the output. It is single ended leaving the board, but in some pictures that were posted it looks like the output from the DAC board is put through some output transformers. See the first pic, The other two pic are of my build. Do I need output transformers. Appreciate any help.

Paul

Hi! This is my first post on this forum, if this question is in the wrong place I apologize. I've been working on a diy boombox using Dayton Audio RST28F tweeters, and I've noticed the frequency response at the top end looks kind of funny. I know these tweeters are supposed to reach all the way to 20khz, but my measurements show that the -3 db point is around 12 khz? Is this normal? The speaker really sounds fine, I can't hear anything lacking in the treble, but just the measurements show a sharp drop off after 11-12 khz. It could very well be that I'm measuring it wrong, I'm using a umik-1 mic with room eq wizard. I did check and confirm the test is going all the way up to 20 khz though. Here's the graph:

Oh and btw, these measurements were taken outside, so room acoustics shouldn't be an issue, even though I don't think it matters anyways at frequencies this high. I'm sorry if this is a stupid question, I'm still very new to a lot of this stuff.

Admin. Please Delete

A

Hi at all.

I am building an amplifier,
I need help to calculate gain .

One 6c45p valve and a Lundahl coupling transformer
with the possibility of step up 1:2 are enough to drive a 300B.

The amplification factor of the 6c45p is approx 54.

Hello everyone. I am designing a compressor with the 6DJ8, but it's my first time dealing with tubes. Its datasheet shows maximum plate voltage rated at 130V, as shown below.



I am designing the amplification stages by biasing the tube from the plate characteristics curves below. At first I was considering the maximum plate voltage of 130V for the bias, as shown in the red curve. The operating point of the tube would be 86V in that case.

A fellow person told me that the maximum plate voltage could be higher than the 130V (as it shows in the "cut-off condition"), and that this value is only there to avoid too much power dissipation, considering the maximum current allowed.

I wanted to know if it is possible to bias the tube say, on the green line, and supply it with ~200V, considering the operating point of ~117V, as shown below. What are the implications of it in a compressor? Is there any danger in going above the 130V?



Every tiny bit of information and knowledge is really important to me. Thanks in advance, people!

How is it possible that a model can be made for several years by a huge corporation and nobody seems to have a service manual or schematic for the Sony TA-1120F - this is the third version of the TA1120 that uses FETs in the preamp and has a completely different power amp section.

Even if it sold only in Japan, you would like to believe that at least one person who worked at Sony or in a service outlet might have one usable copy and be a member of an audio related on-line social group.

I have received a unit that has a functional power amp but has a problem in the Line stage that causes one of the main filter cap voltages to raise up about 30vdc from about 50v to about 80v and causes the other filter cap to decrease by about 30v from about 50v to 20v. I have found that when the B+ is disconnected from the line stage (but not the phono stage or tone control boards) that the voltages remain correct and stable. When I apply the B+ to the line stage board, it causes the 30v shifts.

It would be great to find a schematic...

Does anyone have pictures of the back sides of the three preamp boards that they can share that shows where the wiring is attached to the traces?

I have not pulled all of the transistors from the line board (the middle of the three boards) but I have done some in circuit ohm and diode tests and nothing seems wrong. I received this unit following someone elses attempted repair and I am wondering if they have placed a wire on the wrong trace. I really hate having to reverse engineer this unit, but it sure looks like that is where this is headed.

Can anyone help? No need to reply if you have no idea or no experience with this model.

Thank you!

Hello, I have build my first Aleph 5. Schematic bellow. I have matched IRF9610. Rail voltage +-34V



I have start with just one pair of IRF244 before adding others. When I connect dummy load 8Ohm, everything seems OK. 13v peak to peak before clipping- that is power output I would expect.

When clipping started around 14.5V, it clipping only postive side of sinewave, negative is ok even in much higher output. Somehow assymetric clipping... If I have added more output mosfets, clipping was symetric. With just one pair, always such assymetric - however same behaviour on both channels. Is it something I should deal with?

If I connect 6Ohm speaker instead of dummy load, there is quite big oscillation - 600Khz. Suprisingly, if I lower rail voltage to +-10V, everything going nice. No Oscilation and THD even lower then with +-34V, maximum output voltage cca 14V pk-pk. However, when rail voltage go over +-15, imediatelly there is big 600Khz oscilation.

As it is my first Mosfet amplifier, Im little bit lost how to prevent the oscilation. Im thinking to try increase gate serial resistor from 221 to 1K. Thinking to add some capacitors between Gate and source...however not really sure where to focus first.

Really appreciate any help from more experienced guys here, what should I try. Thank you in advance.

Hello guys. I dont want to repeat this question once again, but is stands against me.
I have homebuilt fullrange open baffle speakers with 93dB eficiency and I have used these with various single ended triodes like 45, 4P1L which can make only small power, 2 watts maximum.
I want the good SET sound, but with better bass and power in general. You will think that good option is to build bigger Se, for example with 300B or simillar power tube. I dont have this option because I have only small power OPT (from rema radio, 5k, 35mA, but these sounded actually pretty good).
With single ended triode, even this small power I get BEAUTIFUL, really GREAT soundstage and things like vocals, timbre, image are great.
Biggest problem is bass. The amp has these great things but at the same time lacks bass energy.
But I have push pull output transformers which were intended for EL34s in pentode. These can have 3.5-4k on each side of the primary.
I can be fine with 4 watts of power.

I have two most important questions:
1. Can I use these output transformers for, for example EL84s in triode or simillar valves?
2. I know that with pushpull I will have better bass, but what about the other things? Timbre, detail, soundstage, imagination... Wouldnt be these worse than with SE amp? This connects to another question which is what good pushpull circuit to use.
Thank you for your time and suggestions.
Best regards, Michal

I recently acquired the above mentioned subwoofer in like new condition. I am trying to determine what the best build type would be for this sub. Home theater use with some but very little music use. I will for sure want it to be vented, but I'm not sure on what orientation. Down firing seems to have my attention right now. Any other configurations that I should consider? Any designs or plans anyone has that I could work with for this driver? Thanks!

I built 12V6 PP monoblock amps with a differential front ends using a 12SN7. The amplifiers use no feedback. I like to have a mute switch on my power amps and, on these amps i also have both single-ended and balanced inputs. So installed a 3-position switch:

Position 1 - balanced input: source connected to the two 12SN7 grids
Position 2 - mute: 12SN7 grids connected to one another no sources attached
Position 3 - SE input: source + connected to 1 12SN7 grid, source earth connected to other 12SN7 grid plus second grid is connected to circuit ground

Initially the Mute position connected both 12SN7 grids to earth but that gave a large thump when used so I reverted to the above configuration.

All worked fine with single-ended inputs and balanced outputs from my Benchmark DAC1 directly into the power amplifiers. I could switch between SE Mute and Balanced with no problems.

Then I built a transformer coupled preamp (Lundahl LL1680 9:1 driven by a 6J5) the output winding of the LL1680 is floating for balanced output (according Lundahl spec sheet) and one end of the winding is grounded for single-ended output.

When using the preamp in balanced output there is a large thumo when switching between mute and balanced output. There is no thump when using single-ended output switching between mute and the S#E input.

I have tried creating an artificial center tap on the winding with two 1k resistors to earth for balanced, but still a large thump when switching.

What gives? As I say when using my DAC's balanced output this does not happen...?

Hello, I’m selling some drivers . PLEASE note they can be sold ONLY in EU countries where parcels do not cross airport security check) Roughly 30% Woofers and 10% tweeters shipped worldwide was returned as dangeruos materials and shipping costs was not returned. Wire bank transfer or Paypal (add 5%) are acepted.



1) 2psc Scan Speak D3806/820000,NEW never used ,only took out for measurements (box/packing have storage damage) 90eur/psc (MSRP 180EUR/psc)

2) 2psc Scan Speak D2905/990000 tweeters. They have new replacement domes from scan speak fitted, one edge of the flange are cut to make it closer to woofer. I can glue/weld and repaint it. 85eur/psc (MSRP 220EUR/psc) SOLD


3) 10+ psc Variuos Scan speak 18w8545/18w8545K /18w4545 (4ohm) Paper carbon clasic series woofers and MIDRANGES (built for Wilson Audio Watt Puppy 7/8 speakers) 70-90eur/psc (MSRP 140-400EUR/psc)

4) 2psc Scan Speak 12M/4631 COATED cone version (center dome was sligtly pushed) 115eur/each (MSRP 260EUR/psc)


5) 4psc Scan Speak 18W8530K00 COATED cone those were 4 ohms versions(built for Alpine F1 status speaker system) but coils replaces with 8 ohms- GENUE scan speak parts. Very light loctite glue is used for repairs 80eur/each (MSRP 200EUR/each)

6) 2psc Scan Speak R2904/700005 tweeters, have some sratches and marke on flange magnets 120eur/psc (MSRP 300eur/psc) SOLD

7) 2psc SB Acoustics SATORI MW19P-4 used for measurements and less 10 minutes playing test 100eur/psc (MSRP 190EUR/psc)
SOLD
8) 2psc SB Acoustics SATORI TW29DN-B nealy new with boxes ,used for measurements and less 10 minutes playing test 100EUR/psc (MSRP 150EUR/psc) VERY EFICIENT tweeters, perfect match with Fostex 8 inch SOLD

9) 2psc Fostex Fostex FF225WK 8" nearly new with boxes ,used for measurements and less 10 minutes playing test 130eur /psc (MSRP 170EUR/psc) please note – they are NOT fullrange drvers - unless you are 70+ years old and have accelerated presbycusis.

10) 2psc Fostex FF165WK with boxes ,used for measurements and less 10 minutes playing ,one of the drive was modified ( remooved dust cap, and glued back with ultralight glue- frequency respone is same as other driver,measurement swill be included if needed) 80eur/psc (MSRP 110EUR/psc)


11) 2psc [/B]Dayton Audio DS270-8 [/B] 10 inch woofers. [/B]nearly new, with boxes ,used for measurements and less 10 minutes playing [/B] 60eur/each (MSRP 85EUR/psc) SOLD

Salas said:

Its the 250VA toroidal transformer building up magnetic momentum. Are you using normal or time delay (slow blow) primary side fuse?

Click to expand...

During my long research on transformer/inrush current, I once stumbled across this long info-sheet about exactly the magnetic momentum of transformators. It's in german, unfortunately, but as far as I understood (that's not that far), it is adressing exactly this issue.
If I got it right, it manages the electric/magnetic impulse of a transformer, but not the inrush current into the capacitors...

Maybe some knowledgeable mind can chime in for more details?

david

Has anyone here tried Rubber Renew on butyl rubber cone surrounds?? I was wondering if it really works or not. I noticed my Dynaudio woofer surrounds are beginning to oxidize and harden little bit and replacing all of them will be expensive as I have to get them from Dynaudio USA and Dynaudio USA has to get them from the Dynaudio factory and make their usual cut as well... That brings them to about 400 USD each! I can have foam surrounds installed but I don't really like the idea of foam surrounds because I don't think they will allow the drivers to maintain the original specs. Any thoughts??? The drivers are 24W75's.

Rubber Renue | MG Chemicals


Thanks!

Mark

Any one have a part list for a mk2 opt2 of a carver m1.0t.

I'm starting to pull my hair out on this one... A little background first....

I re-purchased this amp cheap from a friend who blew it up. Most of the output transistors and their drivers on the right channel were toast.

As it sits now, there are absolutely no output transistors in it (center heat sink is completely empty) and there are no drivers in it either. I'm stumped as to why it still won't come out of protection mode. The one thing that is baffling is that I'm getting good voltages everywhere except the -45V rail (low-power side of the power envelope). I get -65.9 volts on 4-ohm switch position or -71.1 volts on 8-ohm switch position. The 10000uf/50v cap (C510) is in danger. That -71 volts travels everywhere and I don't know where it is coming from. I've checked just about every transistor, resistor, diode and cap in this thing and can't find the problem. AC voltages from the transformer to the fuses and the rectifiers are all good.

Anyone who has experience with this amp and could help me, it would be greatly appreciated.

Hello i am new here, i have this car amp where it wont come out of protection mode, originally problem was battery terminals were reversed.
I have replaced all transistors on the power supply side and 1 side of output transistors and found burnt traces(same side). That side seems good now. Also the 2 driver ics for what I think is output transistors. When everything is together, I get the red light flashing twice and manual says that means voltage is under 9 volts. I am giving 12 v of course, but 4 rectifiers are getting about 8-9V and the other 4 (outer ones) have 0 volts on all legs. This is my first time repairing an amp so idk if it should be like that for the outer ones, but i heard that somewhere around there, there should be a high dc voltage like maybe 80 volts, created from the transformers, that is nowhere to be found, so i think the "gate driver(s)" is the issue and it is not pulsing the transistors on the psu side? Sorry i dont know much, just appears that no high voltage is coming out from the transormers or transistors. I found these 2 tiny ic chips and think they might be the ones responsible for pulsing but i am not sure. I will attach pictures, i cant find these ic parts online either way. The picture has the ic blurry so here is what they say: "8CA 524A". They are smaller than DS0 package size. Also when i removed rectifiers, amp stays on protect mode steady red light but i dont think thats useful. The ic's i already changed are the "s18244 " ones btw(i think this is for output fets). Any help would be appreciated

I have the NAD Amp with the service manual attached. I'm hoping someone can help me diagnose a issue. The amp stopped working a while back. I finally got around to taking a look to see if I can find the issue.

Symptom:
Amp light would turn on, you'd hear two 'clicks' (relays) but nothing worked. No sound output no matter what input was selected.

Sorta cause:
Resistor R46 (In attached capture document) was open. Looks like it got too hot. I ordered a replacement 51O 1Watt resistor and put it in today. Now I have sound, but the resistor is really really hot. Discoloration hot.

More fun:
Looking around I noticed that the resistor seems to have a voltage drop across it of 8Volts. If I did the math right (very likely I didn't) that comes out to about 1.25 Watts (1/4 watt above rating). Obviously, if that math is right, that wouldn't be good.

Looking around even more I noticed that D110 (also marked in attached capture) seems to also be running very hot. It is also rated at 1watt. It seems to also be dropping around 8V (just measuring voltage on one leg then the other and subtracting).

I'm thinking I didn't find the root cause of this issue, that is the blown resistor I found I'm thinking was just a symptom of some other issue. Further I think whatever issue is causing R46 to run hot, it also making D110 run hot. Anyone able to give me some suggestions? I check the other resistors in the area they all measure correctly. I'm an electonics newbie so I'm looking for some help. I'm thinking that whatever is bad must be impacting both devices? But I don't read the schematics well enough to be able to see something that would affect them both like that?

Any ideas?

ps. the amp is working, it discolored R46 and D110 but is working... Could the design just be poor and those components 'normally' run hot?

Thanks for any suggestions guys/gals!



- Craig

p.s.s. Diode D111 is crossed out as it isn't on the board. There is a place on the board for it and it is labled. But it just has a jumper wire across it.

Hi all,

This topic has already been widely discussed in the forum!
And you will tell me that the configuration of the equipment depends mainly on our personal taste, the room where the equipment will be set up, the style of music .... ect

But I'm about to finish my M2 clone , I need to change my old speakers and personally I'm not sure which type and characteristics of speakers to choose! Sensitivity? efficiency ?

So I this thread would be very helpful for me and probably for others.

What a Nightmare!!!

I was allowed to keep my iphone 5s when I was made redundant from my last job. So it was a few years old and free. But recently the screen started coming away from the sides. A bit of internet re-search reveals it's a sign the battery is on the way out. I've spent a lifetime dismantling and repairing stuff and with videos on how to do stuff freely available I bought a new battery. I got the phone apart pretty easily as the screen was coming away already. A few tiny screws and the new battery was in.

That's where the problem started on one of the videos I watched it showed glue being applied to the screen edges to seal it all back up again. I'd bought glue, it came in an incomplete syringe. No needle, no plunger - it's very thin glue it went everywhere and as if by capillary action sucked itself between the LCD and the glass and stuffed the original screen totally.

So what do you do? A screen is just a few bucks more from ebay. But you have to dismantle and transfer a whole bunch of parts from your old screen. Back to the tiny screws again. They are a nightmare the tiniest bit of pressure on your tweezers and the bloody things fly out only to be found by getting on your hands and knees with a powerful torch looking out for a glint. The magnetic screwdrivers flip the screws around when you get them near a hole so that the threads point outwards at the last minute.

I finally got it all back together and working and the screen cracked at the very last minute as I pushed it home.

For now I'll buy a screen protector to cover the crack and when I'm fed up with the cracked but functional screen I'll let a professional replace it. Or maybe I'll start saving for a new phone now.

Total respect for the midgets they employ to assemble these things for peanuts money.

We laugh at the obvious rip-offs. If you had a dedicated listening room and by decree had to spend 50,000 to 100,000$ on new speakers (new only) what would you buy?

Hi everyone!!
Does anyone have document for APLS switch 30 pins of Sanyo Radio? I am having this problem with SW. Thanks all.

So I have a small output transformer to play with coming from an old battery radio. Effectively a 8K push pull transformer. (there is no existing documentation on the radio so its dead).

I offered my classmate a chance to have one tube guitar amp because when he first heard his guitar trough my hifi tube amplifier fell instantly in love with tube stuff.
(I know I wont be able to replicate it exactly to what my big amp sound like but its just the tubes he wants)

Since I wanted to do something he will be familiar with I have chose then Marshall JCM800 schematic.

Basically use the entire schematic as is except the output stage will be consisting of a push pull cathode biased EL84 output.

My only concern is the lack of voltage for the preamplifier and the not required crazy amounth of drive from the phase inverter driver section.

The estimated voltage wont be much more than 320V which is much less than the 470V for the EL34 stage. I am concerned about the preamplifier how will it affect the gain and other characteristics.

Would it be a big problem if I left the schematic completely stock no value change and just undervolt it and call it a day or I will have to change a few parts arround to make it perform properly?

(I am attaching the schematic with voltage measurements aswell. The amplifier I want to make will have a simple cathode bias EL84 output stage not the EL34s)

Proposed thread: since the prior one was closed for straying too far off topic (?) may I propose we open one that will allow discussion of Biology, Immunology, and Anything Else, thereby cleverly skirting the regulations? 🙄

Valve amplifier with diode rectifier.

Hi at all. I have an amplifier with 5Z3 rectifier tube.

I would like to change to solid state rectifier.

Somebody says that really tube amp would have tube rectifier.

But there is a lot of tube preamp and tube amps with diode rectifier.

Of course sound differents both , but somebody could say that diode rectifier sound bad ?

Thanks a lot.

Santiago

When adjusting the attenuators. It used to be much worse prior to Deox-ing them. There is a DC component present while crackling which is of too short duration to be accurately measured.
Can this be the effect of failing capacitors somewhere?
Thanks for looking 🙂

Well, I was able so source some 3/8" jute and finished my Aura NS3 driver Redeyes today. I was hoping they would be a step up fron the NS3 Pico Neos and they are. But it is a small step up and only from the Pico Neos that do not use a filter to boost the bass and tame the highs. In short, the Pico Neos, with a .6mH coil and 20 R filter sound clearly better overall to my ears than the Redeyes. This is confirmed by the measured FR which shows the PNs with the filter to be 4db stronger in the 40 to 80 Hz range. The bass may be a bit tighter in the Redeyes, but not enough to make up for the reduced quanity of it.
I will try the Redeyes with the NP filter in the next couple of days, but thought I would post to see what Wooden Design which uses a 3 or 4 inch driver folks here think would be a clear step up from the Redeyes, especially in the bass part of the spectrum. Aside from several TABAQs this is tne first TL speaker I've built and I have yet to experience the MLTL magic that folks describe, but I sure would like to.

Best,
Jay

Im working on a DD m4b. When I play a 100hz sinewave into the amp the the wave on the speaker terminals looks like this. Any idea why? It still reads as 100hz. Sorry for the upside down pic. Idk why it flipped like that.

Does anyone know where I can find a First Watt F7 PCB and parts kit ?

Thanks

I'm in the process of repairing a 500S, circa 2002, pcb# PC-3082-D (I have the schematics). The initial problem was a blown output FET on the left channel, sending negative rail voltage to the output terminal. I replaced all 6 FETs on the left channel and reset the bias. That channel works well now, with the output going to within 1-2v of rail before clipping with a 4 ohm load.

While testing the other (right) channel, I found another issue. I either missed this during initial diagnosis, or something got damaged during the repair. The output, with or without a load, clips well before reaching rail voltage. The clipping is equal on both the positive and negative side of the signal. Another symptom is that it appears the overall gain of the right channel is less than that of the left channel (for equal input signals). It's almost as if that channel has no gain, and the signal at the output terminal is merely the input signal fed via the feedback resistor (R244).

Tracing the signal through the design, and comparing the bad (right) channel to the good (left), I find the following differences:

- good signal at the + side of C223 (matches the signal at C111)
- bad signal at the base of Q203
- bad signal at the collector of Q201

I used my multimeter's diode test function to test Q201, Q202, and Q203. All appeared fine. I also tested all of the resistors in that part of the circuit, and again all was fine. All of the output FETs test fine too. The +/-14v supplies are also good on the right channel (as tested at R215 and R219).

My initial thought was that Q201 wasn't turning on properly, so I tried shorting the collector to emitter. That didn't help, and made the output look worse.

Aside from starting to randomly replace components, where else should I look?

Thanks!

As requested by unpopular demand, a lounge talk dedicated to biology Q&A and discussion.

I unintentionally contributed to the hijacking of the, still very relevant, supply chain thread in regards to SARS-CoV-2. So here is a thread specifically for the discussion of biology, immunology, virology, and general science as it relates to the current outbreak and larger issues.

Feel free to ask questions (I'll do my best to accurately answer), provide your own thoughts, complain about response, or argue against panic and media coverage. It's all good! That said, I do reserve the right to call you out for misinformation or science rejection in as respectful a manner as possible.

Hi guys. I'm a newbie and I'm looking for some good literature to get started. I found Bob's book and I was wondering if the first part of his book is enough to get me started with some basic amplifier designing. Is there any other literature or tutorials you can recommend me?
By the way, I have some basic (to intermediate) understanding of electronics components and circuits.

Hello!


Let me introduce my home vinyl system, the heart of which are original transistor phono stage and power amplifier of my own elaboration and assembling. Also Canton Ergo 690 DC acoustic systems and old Soviet LP player Электроника ЭП 017с are used. About a month ago I bought a new source - MoFi electronics STUDIODeck+ and maid some records with it.
You can estimate the sound of the system on YouTube:
YouTube


Of course, You Tube records are not the perfect instrument for sound quality evaluation, nevertheless any your opinions would be interesting.

If I have flared port like on the attached picture and need to scale his response to speaker nearfield which dimension should I use in scaling formula? E or D?

Hi All,

I needed a spice model for EL86 tube (triode mode). there are several models on the web but all of them use the simulation method based on some kind of formula. I wanted the model which is derived directly from the datasheet. Since I could not find one, I made it. I use LTSpiceIV and the model might be the program specific, but the methodology is very general and can be used for creating spice models for any triode and simulation programs.
I will describe the process of creating the model step by step.


1. The model is shown in the attached file. In nutshell, the triode is modeled as a voltage controlled current source. The output current is evaluated based on Vgk, Vpk and triode plate characteristics. Plate characteristics are loaded in the model as the points and the spice program does the interpolation. None of the tube constants (u, gm or Rp) are used. The model is simple and can be easily modified for other tubes.
Here are the essential elements of the model with comments and explanations:

a) Connections are Plate (P), Grid (G) and Cathode (K).

b) Dummy voltage source E1 is used to generate the voltage equivalent of V(p,k). E1 is used as an input voltage for the current sources (see below).
E1 n001 0 value {V(P,K)}

c) Dummy voltage dependent current sources (G0 - G12) are used to generate currents representing each I(Vgk=constant) plate curve. There are as many current sources as the curves in the tube plate characteristics. In the EL86 datasheet there are 13 curves (Vgk=0, Vgk=-2.5 .... Vgk=-30). The data comes directly from the plate curves. The curves are the plate current I(mA) vs plate to cathode voltage Va(V) at different grid voltages Vgk (V). The input voltage for each GX current source is E1
Here is the example of the current source for vgk=-5V:
G2 n102 0 n001 0 table (0 0
+ 38.652482 0.000709
+ 41.331757 0.001694
+ 44.011032 0.002561
......
+ 168.794326 0.200355 )

d) Current dependent current source GPK is used to generate output plate current. Current source interpolates current based on the lookup table.
GPK P K value={Table (V(g,k),-40,0,-30,I(G12),-27.5,I(G11),-25,I(G10),-22.5,I(G9),-20,I(G8),-17.5,I(G7),-15,I(G6),-12.5,I(G5),-10,I(G4),
+-7.5,I(G3),-5,I(G2),-2.5,I(G1),0,I(G0))}

e) I(Vp, Vgk=0) curve is used for all positive Vgk voltages. This assumption is not true for the real triode. However, it is quite useful for simulation of the receiving type tubes which should be operated with Vgk<0. In the simulation, plate current saturates when Vgk>0 and waveform is intentionally distorted. You can remove or modify this condition easily to alter tube behavior in the positive Vgk region.

f) Cutoff grid voltage is defined somewhat arbitrarily as an interpolation of the Ip(Vpk) points to Ip=0 at maximum Vpk (in this case Vpk=300V). For EL86 this happens approximately at Vgk=-40V.

Now what's left is to fill the model with the data derived from the plate curves.

2. I obtained the electronic image of the plate curves from the datasheet. My digitizer program (see below) takes jpg, tif and png but does not take pdf files as an input. So, there is an extra step of converting pdf to jpg file.

3. I used GetData graph digitizer from here Digitize graphs and plots - GetData Graph Digitizer - graph digitizing software. You can use any other program, but I like GetData for its simplicity. I imported jpg file to the program and semi-manually digitized all curves. It took me about an hour to get everything right. Digitizer outputs the data in several tabulated formats. I used Excel format for data output file.

4. The last step was to open file in Excel and copy-paste the appropriate data columns in my model text file. To edit the model file I used LTSpiceIV text editor, but notepad works as well.

Comments and ideas are welcome 🙂

I have a set of Polk S20 bookshelf speakers that sounded pretty good with my system. Long story short, they were damaged recently and the drivers are trashed. I've looked at OEM replacements but I am put off by the cost ($65 ea for the woofer, $80 ea for the tweeter).

So my line of thinking is replacing them with a set of drivers that very closely matches the Polk specs. Parts Express has a huge selection and I'm thinking a 6.5" and tweeter from Tang Band might be a good fit for the Polk cabinet and crossover.

When I say specs I'm looking mostly at sensitivity, recommended cabinet size, frequency response and crossover point.

What do you guys think? Does anyone have a recommendation for better replacements? Am I wasting my money and should I just buy those Elac reference speakers I've been drooling over for the last 6 months, lol!

Thanks in advance for your feedback and helpful criticism.

I am trying to design an OTL that will drive ANY impedance cans. My main phones are Audeze LCD-2 CB which are 70 ohms. I also have 32 ohm ohm HE-4xx and 300 ohm HD-650s. I have built four HP amps using Aikido topology, which sound fantastic with 300-600 ohm HP, but not enough oomph for low impedance. I do have 600 ohm OPT but the secondary is only 8 ohms (I was saving them for a 6C33C project). The schematic is attached (preliminary), PS schematic to follow.

Hi folks, once again I need a lone part to complete a repair..

A TIP-140 / 141 or 142 transistor in the TO-247 (larger style) package. If you also happen to have a cosmetically-matching TIP-145 / 146 or 147 that would be dandy. Want to restore the +/-18V regulators on this computer back to factory appearance.

YES! I KNOW THERE ARE MANY COMMERCIAL SOURCES 🙂

Thank you..

Hello everyone here
M new here, trying to understand everything(mostly) here.
M fascinated by the world of audio , speaker, woofers etc. I saw many posts earlier and the r very much helpful, so i decide to solve my problems so i jump here.😀😀

Not exactly tube related but I intend to use this regulator for a tube preamp. When I use the supplied calculator and input 330 v as the desired output (I think the input will be around 350), the spreadsheet says Output voltage adjustment range is 475 high to 375 low. First question, how can that be if I specified 330v output? Second question, heat sink for Q1 say thermal resistance of 5.32. Since I'm a tube guy, not a SS guy, can anyone direct me to an appropriate part number (Mouser or DigiKey)?

I just acquired a CSP2 in "heavy project" condition from a local garage sale. For $100, I couldn't pass it up. It seems to have been modded by the previous owner and I would like to return it to OEM. Looking forward to the resurrection process. Could anyone share a schematic? Thanks in advance.

The purpose is to simulate different dogbox designs for the 18-sound 10nmba520. This is the driver chosen by Troels Gravesen for The Loudspeaker, The-Loudspeaker

First I use Winisd to figure out a critically damped box size, and its potential maximum sound pressure.

Box size is 11,39 liters. Filter parameters are shown in diagram. System power is 130 W, cone excursion is xmax at 150 Hz.

Hello all.
Okay, I've been lucky with trial, and error troubleshooting, and eventually repairing circuits. Don't want to waste anyone's time here with stuff I should already know. But I just can't figure this one out.
Getting weirdness from WT800 in bridge mode.
First ting I did was replace the open 27K feedback resistor that had failed open.
In bridge mode, I'm getting a larger signal on negative side (inverted right channel) than I'm getting from the positive side (non-inverted left channel).
Both right, and left channels are putting out the correct wattage in stereo mode.
Bridge switch seems fine. The R channel input is being muted by JFETS when in bridge mode. Getting signal from L channel output at 12K/27K junction.
When scoping output negative terminal I'm getting 36V RMS before clipping
Positive terminal is reading 22V rms.
At this point, I can apply more signal and get 36V on Pos teminal as well, but the negative side is clipping.
With the above 36/22V RMS scenario, I'm reading 58V across NEG and Positive with DVM.
Obviously, far below the specified 800 watts for bridged into 8 ohm load.
Using electric stove hotplates paralleled to get a perfect 8 ohms.
Hoping someone can see something obvious here.
I appreciate, and humbly await any response to guide me.
Thanks,
Stan

http://schems.com/bmampscom/eden/Eden WT500, WT600, WT800 - Schematic.pdf

Hi, I have two hammond 373bx power transformers. I've used hammond transformers a lot and they always work great. But now these two, both!, i wired them up to my variac, blue and white on the variac and brown and black wrapped together and .... nothing. Both won't do anything. No high voltage, no 6.3 and no 5 volt. If I bump the voltage to about 100 volts on the variac, the high voltage starts to swing between 0 and 50 volts. I don't get it. Thist is not my first time. What the heck am I missing? :/

Here is the wiring diagram:

Dear All,

I have an issue that leaves me puzzled. I have a totally DIY system, amps, pre, etc. The system is completely silent. One of the source is my Home theater amp for the front channel. When I attach the amp, the system is still completely silent.
I have a very strong hum when I attach the TV to the amp via HDMI. Note that the TV is NOT the source of audio, but it is used only as a monitor. Both TV and Home Theater amp (Denon 3808) do not have grounding.
An even more nastly noise I get if I connect the Macbook as a source via HDMI. in this case I can hear the hard drive moving.

Any solutions ? I could not find any HDMI galvanic isolator in the market.

Thanks for help.

D.

Hi I am relatively new to electronics so please take it easy on me.

I am building a DIY Bluetooth Speaker, everything works fine when I use my breadboard amplifier that I build using LM386. But I need a stereo output to decided to use the PAM8043 Amplifier IC. To save time I directly purchased the PAM8043 Amplifier Module from the link.

As you can see in the image (from the link) the module is powered by +5V and ground and the audio input L,R and Ground. Should I connect the audio ground with the power supply ground? My logical brain says it should not be done, but when I don't do it I get a humming noise and when I connect both grounds it the PAM8043 is getting hot. So what could be the problem here?

Does anyone know the value of R1 for the power led?

I am working on my first crossover network from scratch, probably a 2nd order 2-way. My questions are twofold:

1) Is there any difference in performance if I build them with point to point on a perf board vs using a stock foil board with the large pads/grounds?

2) Most of the stock foil boards are only for the basic 4 components plus maybe a fuse. What do you guys do for L pad resistors, Zobel, BSC etc? Is everything on the same board or is there a second board?

Thanks,

George

Is there a way to reduce the LF in a full range speaker?
Filter or crossover perhaps?

Thanks

There's a company that makes one of the leading guitar amp\simulators out there, called Kemper. They just released a custom 12" whizzer driver called the Kone that is meant to use their proprietary DSP in the amp to coax near full range response from the driver. I have one for use with their system, and using the DSP and external audio with it set in full range, was frankly shocked at how good it sounded with high quality audio. Far better extension and less tubby mids than a stock Eminence 12LTA.


The driver design is described as having a modified whizzer that allows higher frequency response, but it appears the overall response of the driver is not usable without their DSP correction. It would be interesting to throw a RTA on one of these and see how it does full range. Also it is only available in 4 ohms.


The site shows the Kab (a standard 12" cab with a Kone installed), but you can purchase the Kone driver on its own. It's made by Celestion in China, and is very high quality with a beautiful look.


KEMPER Kabinet & KEMPER Kone | Kemper Amps

Hello,

I have just read some piece of information I found interesting. It is taken from http://www.rcm.com.pl/cec/cec_main.htm , and it concerns CEC's new integrated amp, AMP71. The original text is in Polish, here is my (poor 🙁) translation. I may have messed it a bit, I believe HPotter would do a better job. Anyway, here it is:

AMP71 works in Class-A, giving 200wpc max, without generating huge amount of heat. Enough to say, that heatsink temperature of a working amplifiers does not exceed 40 deg. C. What's more interesting, all A class amps, with power exceeding humble 30wpc, have large cases with enormous power supplies. AMP71 has traditional ps with 160000uF caps and two highest 🙂)) quality toroid transformers (650W each). Using two toroid is caused by fully symmetric design, including speaker terminals, not connected to the ground. Basic idea is very simple from theoretical point of view, yet its implementation is not that simple. To make long story short, signal is amplified by single bi-polar transistor, working in pure class A. It amplifies signal from input, which basically means that AMP71 does not contain pre-amp section, and the whole amplification is done by single gain stage without feedback. (...) The most interesting part is how to gain 200W in class A using only one gain stage. As we were said by designer, Mr. Carlos Candeias, gain is set between 40 and 50, and with given 100mV input sensitivity results in 5V max on the output. So where is that 200W coming from? The gain transistor is supported by current source made of 8 transistors per channel, that can easily generate 200W while working in A class (its very high impedance does not influences the signal). Roughly speaking, the power transistor works as switch controlling the
current transistors. The whole process is controlled by detecting output signal and informing the current source about changes, that are apropriately amplified. (...)

Does it sound familiar? Any comments, guys?

Regards,

Marcin.

hi members ...

i need to build a gain module to compensate for the input sensitivity of my TDA8950 (dont know why it has low input sensitivity). But now the problem is after the low pass filter the signal will pass into an inverting op-amp section which has gain of around 8db and this has given me Hum problem when the subwoofer volume potentiometer is turned more than 60%.

Low pass filter is 2nd order LR and there is an inverting summing opamp stage that combine the Left and Right channels and this stage has unity(1) gain ... only the final stage operates with gain while inverting back the signal phase

thanks