Using BDX53A and BDX54A for an amplifier

[Robert8192]

Hi,
I am building a little transistor amp and have a couple
questions.
I found this link
Guitar Amplifier

and like the circuit a lot.
I am not building the PREAMP parts as I have a good
preamp to use.
My question is. I am placing the BD139 with BDX54a and b,
all on the same heatsink,

The collector for BDX54A is grounded and the datasheet says that
the collector for both transistors connects to the mounting
base.
Does this mean electrical with BDX53A also,,, as That connects
direct to the positive voltage.
Do I have to use separate heatsinks for them??

And, has anyone built this amplifier, I wonder how they worked
it and how it sounded??

Thanks a lot.

Robert8192

[Jazz P Bass]

Heatsink

You better isolate the one on the upper part of the schematic.
The collectors must be kept separate.
mica insulator - MCM Electronics Search

[jrfrond]

Personally, I'd scrap everything after the volume control and it's coupling cap and go with a TDA2030 amplifier-on-a-chip. Here's the data sheet:

TDA2030 Data Sheet

[Robert8192]

Hi - Thanks

I will build an amp using TDA2030, but
just trying to see what different amp
circuits will sound like..

I have 4 excellent circuits..










I will prbably build the AMP section of the Audition-20 amp
as it is looking like a pretty sound amp.

Has anybody built a homemade version of any of these??
or any other Silicon variant??

Thanks.

[Steve Conner]

The power stage of that amp is just a very basic discrete power amp. There's nothing magic about it that I can see: you shouldbe able to substitute any other power amp.

I thought the old Maplin Mosfet 100 watt power amp was about the best discrete circuit for musical instrument use. It recovers cleanly from clipping, and there's no protection circuit to hang up when driving inductive loads.

http://www.eastmarinedrive.com/conte...n/circuit2.jpg

87MOSFET

Unfortunately the lateral MOSFETs are expensive and it won't work with the ordinary switching FETs. You don't get the 2SK135/2SJ50 any more, but there are other compatible devices.