Another classic that uses 2N3055's is the Klein + Hummel OY studio monitor. It was quite modern 52 years ago: fully transistorized, partly active crossover (active between the woofer and the rest, passive between the squawker and the tweeter), amplifiers with DC coupled outputs. See Sonderdruck Funkschau 1968, Heft 8.
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Here is more about German amp, from Russian and East German sources. Even though it's using 2N3055, it seems to be decent amp.
Spice sim attached.
42V rails might be too much for these transistors, but it can do +/- 35V.
With 35V rails, and R2/R4 at 2k5, it can do nice 40-50W amp, with Thd 0.001
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Sorry but I only see an overly complicated typical simulated-only amplifier, which to boot lacks in important areas, such as the Class B "biased" power transistors.
To complicated for you?
I find it slim and elegant, but never mind...
By the way, the power transistors are "biased" in class C
2N3055
Hi 008080,
A well respected design for many years that used the 2N3055 was the Bedini 25.25! Do you have a picture of the 3055's that you can post. John Bedini specifically used the "H" version. The amp is a 25 W Class-A so will need large heatsinks and ideally a 160 VA toroidal per channel. It uses seven off 3055's per chanell. I have used mine for 30+ years. I'm finally replacing the original PCBs as they are shot. These amps are known for their ability to drive difficult loads such as the Quad ESLs.
If interested drop me a PM and I can give you more info.
Kevin
Hi 008080,
A well respected design for many years that used the 2N3055 was the Bedini 25.25! Do you have a picture of the 3055's that you can post. John Bedini specifically used the "H" version. The amp is a 25 W Class-A so will need large heatsinks and ideally a 160 VA toroidal per channel. It uses seven off 3055's per chanell. I have used mine for 30+ years. I'm finally replacing the original PCBs as they are shot. These amps are known for their ability to drive difficult loads such as the Quad ESLs.
If interested drop me a PM and I can give you more info.
Kevin
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Surely not the best?
2N3055H's were good in their day, but barely managed the audio frequency range. Using 2N3055(H) as a driver is going to be quite slow, and 680pF Miller capacitors will be quite slew rate limiting.
If Bedini was concerned about second breakdown - a good reason to specify "H", BTW (especially in Class A) - then modern faster devices can match or outperform.
2N3055H's were good in their day, but barely managed the audio frequency range. Using 2N3055(H) as a driver is going to be quite slow, and 680pF Miller capacitors will be quite slew rate limiting.
If Bedini was concerned about second breakdown - a good reason to specify "H", BTW (especially in Class A) - then modern faster devices can match or outperform.