Now that is what I call a burning amp.
What bias current will you be using?
I look forward to seeing the finished product.
Yes, I am in this trap.
8 Ohm loudspeaker, 88 db. Result, very nice sound with BA-1, but only small power for Stanley Clarkes bass, a little helpless.I have three output devices at 2 A. More is not possible with my heat-sinks
BA- 2 with the same current has much more dynamics and Stanley feels good, but the overall sound is a little bit dull and dark in my chain. Especially compared to the Semisouth variation on BA-1.
I think I will buy new heat-sinks and go to four or five devices with BA-1.
Yes, I am in this trap.
I have three output devices at 2 A. More is not possible with my heat-sinks
BA- 2 with the same current has much more dynamics and Stanley feels good, but the overall sound is a little bit dull and dark in my chain. Especially compared to the Semisouth variation on BA-1.
I think I will buy new heat-sinks and go to four or five devices with BA-1.
Why don't you do the semisouth variation on BA-2?
Toshibas at the output might help a little bit also.
3 devices should easily do 4A with 25V rails (1.33A per device).
You might also need a bigger transformer (eg 500VA or higher per channel depending on how high you set the bias).
Anyway go for it, you definitely don't want to upset Stanley.
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That doesn't really answer my question.
By the way, for push-pull output stage, 3A bias gives you 6A class A.
It would be nice if you could give some description of the sound at different bias points (eg at 1A, 2A, and 3A).
Assuming the minimum pot setting (I hope you measured it with a multimeter) gives you the minimum dc offset (ie 460mV) then you need to change R25 from 15k to 14k.
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I meant putting it at Q203. Change IRF610 for Semisouth. I think Nelson suggested it earlier.
If you can fit a heatsink on it you could also also experiment with biasing of the driver stage.
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Oh, I did this already ...... Sounds better for me, than 610. Although I do not really know what to change for the lower Vgs.
I have heard BA-1 with SS in the front stage and as a substitute for the half of the 240s and it spoiled me for any other combinations, no more F5, no BA-2, no F4 etc. ......am I crazy?
It sounds like you need to get the biggest heat sinks you can find.
You could try something like an Aleph 3 chassis but with bigger heatsinks eg 4 of these MF35-151.5 per channel (So you need 8)
Conrad Heatsinks - Products
That should allow somewhere between 300W to 400W dissipation per channel, or 6A to 8A with 25V rails.
You might not need to go that extreme.
If you could do some measurements with the BA2 while running Stanley you could determine what bias current you need for the BA1 (Probably add another 30% for good measure).
You could try something like an Aleph 3 chassis but with bigger heatsinks eg 4 of these MF35-151.5 per channel (So you need 8)
Conrad Heatsinks - Products
That should allow somewhere between 300W to 400W dissipation per channel, or 6A to 8A with 25V rails.
You might not need to go that extreme.
If you could do some measurements with the BA2 while running Stanley you could determine what bias current you need for the BA1 (Probably add another 30% for good measure).
You might also wanna look at this:
HeatsinkUSA
btw:NOT affiliated with them
I just couldn't find any cheaper ones for their sizes, if you find any please PM me.
Greetz Ava
HeatsinkUSA
btw:NOT affiliated with them
I just couldn't find any cheaper ones for their sizes, if you find any please PM me.
Greetz Ava