Hi Guys,
I would like to built a new power amp. I have many parts here, 2 xformer 35-0-35 Vac 2500VA, Bjt output 8 mjl1302 and 8 mjl3281 onsemi, driver toshiba 20 2sa1930 and 20 2sc5171, 10 2sa1381 and 10 2sc3503, 20 MJE15030 and 20 MJE15031, many 2n5401 and 2n5551, many BC546B and BC556B, many 2sa970BL and 2sc2240BL and many 2SK170BL and 2SJ74BL.
I want can put a Dunlavy SC-IV on this amp without problem. Somebody can suggest me? Thank you! Maxpou
I would like to built a new power amp. I have many parts here, 2 xformer 35-0-35 Vac 2500VA, Bjt output 8 mjl1302 and 8 mjl3281 onsemi, driver toshiba 20 2sa1930 and 20 2sc5171, 10 2sa1381 and 10 2sc3503, 20 MJE15030 and 20 MJE15031, many 2n5401 and 2n5551, many BC546B and BC556B, many 2sa970BL and 2sc2240BL and many 2SK170BL and 2SJ74BL.
I want can put a Dunlavy SC-IV on this amp without problem. Somebody can suggest me? Thank you! Maxpou
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With such a transformer , the poor devices on the left
can only hope that such a question will stay unanswered....
Why?
Well , maybe all for one channel .....
you believe I don't have enough parts to built 2 channel. Maxpou
With two transformers, you can stack them up end to end and make +-70 VAC. Of course, it would be incredibly heavy. Then your number of output transistors and heat sink size would limit your power. Better install good overcurrent (output) protection.
Cool Andrew says you can get 29 VAC out of 35 VAC rails. The amps I have been working on produce about 2/5 to 3/5 the rail voltage on the speaker output by specification. I thought modern transistors might be better.
Cool Andrew says you can get 29 VAC out of 35 VAC rails. The amps I have been working on produce about 2/5 to 3/5 the rail voltage on the speaker output by specification. I thought modern transistors might be better.
Max,
You have the trafo, so why not use it.
It's only going to give you a little over 50V rails which is fine for a 100W//8R amplifier, which needs, for flexibility, three output pairs of the transistors you have chosen, which have a Vceo of 200V.
The only problem with the trafo is the inrush current. It will likely take out your household circuit breaker, as it's about five times the max current. For a 2500VA trafo at 120Vac mains, that's around 105A, so you might want to use a soft start!!
Cheers,
Hugh
You have the trafo, so why not use it.
It's only going to give you a little over 50V rails which is fine for a 100W//8R amplifier, which needs, for flexibility, three output pairs of the transistors you have chosen, which have a Vceo of 200V.
The only problem with the trafo is the inrush current. It will likely take out your household circuit breaker, as it's about five times the max current. For a 2500VA trafo at 120Vac mains, that's around 105A, so you might want to use a soft start!!
Cheers,
Hugh
there was a guy looking to build a 6kw top shelf power amp for <120usd shipped posting in this forum yesterday, perhaps you can help him out? 
he appears to be as serious as you are..
hehe sorry i'm just joking, thats some serious hardware youve got there, you would want to keep such a piece of iron separate from the amp section wouldnt you? or even with TX this big radiated noise is not as big a problem as you would think?
yes i would think an actual softstart would be needed here, not just a CL60
he appears to be as serious as you are..
hehe sorry i'm just joking, thats some serious hardware youve got there, you would want to keep such a piece of iron separate from the amp section wouldnt you? or even with TX this big radiated noise is not as big a problem as you would think?
yes i would think an actual softstart would be needed here, not just a CL60
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to maximize the trafo...you might want to build 4 channel or 6 channel 100w/8ohm amps so you can go tri amp stereo. or 4 channel bridge to get the power you need if you really want it....but consider aksa and H_a advice on softstart...
there are lots of schematics here that will suit your needs...just look on the threads...
there are lots of schematics here that will suit your needs...just look on the threads...
Fully balanced amplifier for 2,5 kVA transformer
Hi maxpou
Look, my suggestion and potential support will be very reasonable for the circumstances (transformer) you have.
Make fully balanced power amp, practically meaning to build four completely identical channels with 4 BJT output pairs per channel, 20mF rail caps per channel and for the input you will use XLR plus RCA connector, so really universal use with un/balanced preamps. Input phase splitter schematic attached.
Aha I almost forget hehe, the power will be 500 Wrms on 8 ohm or in the best case 1 kWrms on 4 ohm.
Regards, Andrej
Hi maxpou
Look, my suggestion and potential support will be very reasonable for the circumstances (transformer) you have.
Make fully balanced power amp, practically meaning to build four completely identical channels with 4 BJT output pairs per channel, 20mF rail caps per channel and for the input you will use XLR plus RCA connector, so really universal use with un/balanced preamps. Input phase splitter schematic attached.
Aha I almost forget hehe, the power will be 500 Wrms on 8 ohm or in the best case 1 kWrms on 4 ohm.
Regards, Andrej
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Given the number of output devices you have (16 IIRC), I think you can build a very capable 150W per channel amplifer (8 devices per channel, following the rule of thumb of 1 pair TO3P for each 40-50W).
Big transformer will be a bit wasted, but the important thing is you have it - so just go for it. The only other expensive items are the smoothing caps and a case so you are already half way there.
Big transformer will be a bit wasted, but the important thing is you have it - so just go for it. The only other expensive items are the smoothing caps and a case so you are already half way there.
Your transformer looks more like it was designed for a welder or something needing a crazy amount of current. It is probably going to buzz like a hive of angry wasps. It'll work, but it's totally impractical for an audio amp. As mentioned, the inrush current is going to be a nightmare
Save yourself a lot of hassle - sell it, and buy a good 2x35V 500VA toroid. You'll get a nice 100W amp out of that with the transistors you have.
Save yourself a lot of hassle - sell it, and buy a good 2x35V 500VA toroid. You'll get a nice 100W amp out of that with the transistors you have.
you'll get four nice 100W amplifiers out of.....
A 2pr output stage is usually enough for any domestic listening situation.
Hi Guys thank you!
Hi Hugh,
thank you for reply. If I put three output pairs per channel do I have 200W at output? What the difference if I put 5 output pairs per channel? For the softstart I knew because I tried to plug only the transformer and the circuit breaker has tripped but my I tried to startup with 150W light bulb and it's OK.
Hi Hannes,
thank you for your suggestion with the CL-60, but the CL-60 is 10 ohms and I thought put 40 ohms in series with the primary, I'm correct or not 40ohms maybe too high? Thank you! Maxpou
Hi Hugh,
thank you for reply. If I put three output pairs per channel do I have 200W at output? What the difference if I put 5 output pairs per channel? For the softstart I knew because I tried to plug only the transformer and the circuit breaker has tripped but my I tried to startup with 150W light bulb and it's OK.
Hi Hannes,
thank you for your suggestion with the CL-60, but the CL-60 is 10 ohms and I thought put 40 ohms in series with the primary, I'm correct or not 40ohms maybe too high? Thank you! Maxpou
Hi Lazy Cat
Perhaps I have not your wallet to build four channels and my preamp and cd player don't have a XLR connector.
Maxpou
Hi maxpou
Make fully balanced power amp, practically meaning to build four completely identical channels with 4 BJT output pairs per channel, 20mF rail caps per channel and for the input you will use XLR plus RCA connector, so really universal use with un/balanced preamps. Input phase splitter schematic attached.
Regards, Andrej
Perhaps I have not your wallet to build four channels
and my preamp and cd player don't have a XLR connector. Maxpou
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