The Kleinschmidt 10A

[GK]

What kind of interest would there be out there for a very simple, but good performing 10W class A (into 8 ohms) rated power amplifier:

a) specifically designed to be build as a monoblock.
b) TO-3 complementary BJT output.
c) Of the single polarity supply / capacitively coupled load topology with the esoteric twist of having a common as muck 12AX7 twin triode in the front end.
d) Specifically designed to be built from non-esoteric, cheap, universally available parts.
e) All components (bar the two transformers and one bridge rectifier) PCB mounted for ultra-easy assembly.


I have design I made quite a while ago and considering the popularity of the JHL class A, I’m seriously considering publishing it and having a batch of boards manufactured (to be sold for profit in fame only)
Specifications are not subject to negotiation, and no audiophool blowhard arguments about the evils of coupling capacitors and mixing SS with toobs, thanks.

Cheers,
Glen

[janneman]

Welcome back ....

Jan Didden

[peranders]

The interest is always there if you accomplish something that works. TO3 Why? It's not very wise to use an almost obsolete package. TO220, 218, 247 or similar will just fine.

If you do a pcb you may have room for both TO92 and SOT23, SOT223 parts. Those parts aren't so hard to solder and you will have a lot more types to choose from. You can also make room for 1206 decoupling caps. It costs nothing to do this.

[GK]

Originally posted by peranders
The interest is always there if you accomplish something that works. TO3 Why? It's not very wise to use an almost obsolete package. TO220, 218, 247 or similar will just fine.

If you do a pcb you may have room for both TO92 and SOT23, SOT223 parts. Those parts aren't so hard to solder and you will have a lot more types to choose from. You can also make room for 1206 decoupling caps. It costs nothing to do this.

Hmmmmm....... the TO-3 package will still be with us for some time to come and some of the cheapest and most robust trannies for this application come in T0-3.
If some newbie builds this class A thingie and cranks the bias up too high the first time round, or does a test run on inadequate heatsinks, a pair of TO-3's could be a blessing (especially over TO-220's).

The instrumentation stuff I design / build on a professional basis uses SMD universally (example below), but I don’t think I’ll bother redoing this design for optional SMD parts (sandwiched between big electros, a twin triode and some 5W resistors)......

Cheers,
Glen

[Jan Dupont]

How about showing us what you have in mind

[GK]

OK, here is my little baby. Maybe it will arouse some excitement

[peranders]

Originally posted by G.Kleinschmidt



Hmmmmm....... the TO-3 package will still be with us for some time to come and some of the cheapest and most robust trannies for this application come in T0-3.
If some newbie builds this class A thingie and cranks the bias up too high the first time round, or does a test run on inadequate heatsinks, a pair of TO-3's could be a blessing (especially over TO-220's).

I think you are doing things much easier using modern parts. You were talking about 10 W class A not 100 W so I can't see the advantage with TO3, only more difficult to mount. In this design job you have also to specify required heatsink It's an obvious advantage to keep everything on a single pcb, much less room for error.

Originally posted by G.Kleinschmidt
The instrumentation stuff I design / build on a professional basis uses SMD universally (example below), but I don’t think I’ll bother redoing this design for optional SMD parts (sandwiched between big electros, a twin triode and some 5W resistors)......

If you put a lot of work into this, why not add these small practical things?For me it's not trouble at all to connect a SOT23/223 transistor in parallel with a TO92. It takes me a sconds, maybe a minute.

[GK]

Originally posted by peranders

I think you are doing things much easier using modern parts. You were talking about 10 W class A not 100 W so I can't see the advantage with TO3, only more difficult to mount. In this design job you have also to specify required heatsink It's an obvious advantage to keep everything on a single pcb, much less room for error.

If you put a lot of work into this, why not add these small practical things?For me it's not trouble at all to connect a SOT23/223 transistor in parallel with a TO92. It takes me a sconds, maybe a minute.

It would likely only take me a minute or two to shave my thighs also, but that isn't much of an argument for doing it.

10W class A still gives ~30W idle dissipation. The bias can also be cranked up for 20W into 4 ohms - then we have closer to 55W idle bias.
And sure I can specify the correct heatsink, but that doesn't increase the designs dummy proofness.
Anyway, the board layout was done a while ago already, so it's a moot point.

Cheers,
Glen

[janneman]

Originally posted by G.Kleinschmidt
OK, here is my little baby. Maybe it will arouse some excitement

My, so many active devices for 10W...

My L'Audiophile Nemesis has only 1 (one) and gives me 12W

Jan Didden

[GK]

Originally posted by janneman



My, so many active devices for 10W...

My L'Audiophile Nemesis has only 1 (one) and gives me 12W

Jan Didden

Well this thread has certainly been worth it so far...........................................