BA-3 Amplifier illustrated build guide

https://www.mouser.ca/ProductDetail...=/ha2pyFadugpge1dGluweDJ2DvcDZehkralshEOkxSM=

These are fine, used in the guide and by many. A bit larger than the ones Nelson used in the manual. If using higher voltage rails or higher FE bias than spec, these Aavids are fine. Though I would want even more sink, meaning making myself or adapting some larger ones, since ime increasing the FE bias in this circuit can be quite beneficial.

Regards,
Andy
 
I second 100mA Iq. I have tried approx 70, almost melting the fets. And what a difference compared to 45mA. Also, 100mA is OK without reducing resistor values (22Rs).

I think I have some of those sinks actually. When I make final iteration BA-3, I’ll put them to use :cheers:

Regard
 
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RN55 are rated by Dale for the military at 0.1W (up to 0.125 at a lower temp). I have been told that with the Dale resistors categorized for military use, the ratings can be doubled conservatively. That is not my own personal knowledge, but I trust the source.

That still does not get into the 0.5W range.

For that... I'd start (within the same Vishay Dale lineup) with the RN60 (0.25W) and work up to the RN70 (0.5W) for what might be overkill. I used RN60s.
 
You’ll probably need something between 3A5 and 5A slow blow. On 230vac and aame values, I got away with 1A8-2A fuses. 1A8 kept blowing from time to time. Depends on how well your soft start solution works, maybe bias too if you max out. I’d just order up a few different values between 3A5 and 5A and see what ends up just not blowing, as Papa prescribes.

Remember slow blow types is the way to go.

The exact value will depend on several variables, and is probably best answered by someone with those exact transformer values on a 120Vac line.

Regards,
Andy
 
No prob, glad to help. Maybe grab a 3A25 too, and 5A25-ish, just in case. Though I kinda doubt it.

Start low, go higher after each blow. If you start high, and use a thermistor for soft start, it will get hot between switches, meaning higher current draw, and you may end you choosing too high a value in the end. Or just wait for it to cool between switches :cheers:
 
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Just a positive feedback about BA-3 amp

After 3 weeks of listening, passing through a couple of bias re-adjustment, I can only say what a beauty! warm and detailed, powerful with a great speaker control.

My current setup is standard, 3 pairs output devices x channel (complementary out).
I am now really curious to test the version with 6 pairs