Best 2n3055 amplifier

[008080]

Hello, I'm looking for the best 2n3055 amplifier project. I have a lot of this transistors so i want to use them. The project should be modern and the amp should have good parameters. Thanks!

 

[gpapag]

Pay a visit to this thread. Lots of choices.

2N3055 inside - commercial famous amplifier models, quasi complementary power output

George

 

[008080]

Thanks! I'll take a look. Have you seen 2n3055 amplifiers with DC servo?

 

[Mark Tillotson]

With 2N3055's the project will not be modern by any stretch

 

[OldDIY]

1.2n3055 are different.
2. There are different schemes.
3. What do you expect from a DC servo drive?

 

[008080]

1.2n3055 are different.
2. There are different schemes.
3. What do you expect from a DC servo drive?

1. I know
2. I have only NPN, so quasi complementary
3. To minimize DC offset at the output

 

[OldDIY]

Wiederhold М. Neuartige Konzeption für einen Hi-Fi - Leistungsverstärker
Radio Fernsehen Elektronik, 1977, No14, S. 459-462, 467
Стр. 61 журнала <<Радио>> № 4 за 1978 год
Class B w/o crossover distortion (1975)

 

[OldDIY]

Here
A Paul Kemble web page - compact PA designs.

 

[wg_ski]

That one doesn’t exactly “minimize DC offset at the output”. You would need a separate bootstrap capacitor to keep the VAS current out of the speaker. Easy mod if you wanted to do that.

Cap coupled speaker is probably a good idea when using 3055’s of unknown origin above their 60V rating. If they blow you just lose a couple of expendable 3055’s (and a Cheap BD139/140 pair) and not the speaker. A DC servo won’t be able to correct that situation.

 

[008080]

That one doesn’t exactly “minimize DC offset at the output”. You would need a separate bootstrap capacitor to keep the VAS current out of the speaker. Easy mod if you wanted to do that.

Cap coupled speaker is probably a good idea when using 3055’s of unknown origin above their 60V rating. If they blow you just lose a couple of expendable 3055’s (and a Cheap BD139/140 pair) and not the speaker. A DC servo won’t be able to correct that situation.

I have stronger version of 3055 - KD503 made by Czechoslovakian Tesla

 

[stanislav1957]

Classic.
Author of the scheme V. Lamm/ Vladimir Shushurin

 

[moschfet]

Hello, I'm looking for the best 2n3055 amplifier project. I have a lot of this transistors so i want to use them. The project should be modern and the amp should have good parameters. Thanks!

This is an amp that I actually designed with Toshiba Power Transistors, but the circuit works also good with 2N3055.

 

[008080]

Thanks for all your propositions, what do you think about QUAD 405 with KD503 output transistors?

 

[OldDIY]

Slow

 

[minek123]

This is an amp that I actually designed with Toshiba Power Transistors, but the circuit works also good with 2N3055.

How thermal tracking is done? Which transistor is doing it?

 

[KatieandDad]

Thanks for all your propositions, what do you think about QUAD 405 with KD503 output transistors?

I built a Quad 606 clone with MJ15003 transistors, I had problems with stability. It might work better with the 2N3055.

 

[moschfet]

How thermal tracking is done? Which transistor is doing it?

I have build a similar circuit with 2SC5200 and 2SA1943. In class AB/C it worked already, but in class AB it begins to oscillate.
In class AB/C, thermal tracking also worked fine. The power transistors are switching on when the driver transistors go over 24mA.
If you look at a 20kHz signal, you can see small transfer distortions, but these are in the range of a few hundred kHz with a tiny amplitude. Not even bats can hear that

This would actually be a case for current dump, but my previous experience with current dump has been rather disappointing.

 

[john_ellis]

I suggest the best 3055 amp would be a Blameless-type architecture but with a quasi-complementary output stage if that's what you require.
I presume your 2N3055's are modern epi devices, not RCA original (slow) ones.
Crossover distortion can be reduced if the frequency compensation is made with a local inclusive compensation which can also be given a transitional compensation, but the circuit needs a couple of minor adjustments - mainly an increased input stage degeneration and an increased VAS degeneration from Self's original.

 

[stanislav1957]

Mini amplifier

 

[bogdan_borko]

Thanks! I'll take a look. Have you seen 2n3055 amplifiers with DC servo?

Servo has no connection to type of transistors used..
Btw I remember making my first amp with those old TESLA KD bjts, in late 80's I could only find the datasheet with numbers, hfe>40 and ft 2Mhz.