Leach Super Amp Pcb Re-Design (LSAPRD)

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pooge

Member
Joined 2003
Jen,

Just a few comments on board layout after working with your Leach amp boards.

1) Provide more room around the electrolytic in the feedback for physically larger cap options, and provide a plurality of lead hole spacings to allow for options in part selection, such as Black Gate caps in the 470uf range.

2) In the same idea of parts options, provide for optional lead arrangements for the differential transistors, as some swap the leads. Their are good options in the Toshiba line for input transistors, where two of the leads are reversed from "standard" lead outs.

3) Ideally, and if possible, layout the differential transistors so that the flat sides in a pair face each other, so they can be glued together easily for thermal coupling to one another. I have never seen this done, and haven't even looked at the layout required, so I don't even know if it's practically doable without compromising elsewhere. But it would be nice to have them thermally coupled in an easy-to-do manner.

Hope this helps.
 
still4given

still4given

Member
Joined 2004
Tony said:
hi jens,

i would be more comfortable with the output trannies in 4's instead of 3's.

also would it be possible to have the output stage expandable, so we can add more trannies should we feel the need?

thanks
Click to expand...


Wouldn't 4 sets just make the PCB even longer? Prof Leach used TO-3s and only used two sets. I think Jens has three sets because they are plastic devices. One of the reasons for Jens' design, I think, is to avoid all of the wires associated with the original design. I suppose this amp could be made with optional output boards, but then you are back to wires again. With the design Jens has here there are already 12 output devices on the board. Going to need a pretty big heatsink to fit more.

Blessings, Terry
 
geezer1944

geezer1944

Member
Joined 2005
Yup,
temp_jens/Super%20Leach_ver_0.9.pdf

gets translated wrong over here as
temp_jen...ach_ver_0.9.pdf

If one were to type in the http://www.delta-audio.com in front of /temp, then the forum computer system will translate it as......
http://www.delta-audio.com/temp_jen...ach_ver_0.9.pdf
A short naming convention usually prevents this.
% signs in a URL name generally confuse the system.
BTW, all computer links will work from your own machine.

Regards,
Elvin
 
rolandong

rolandong

Member
Joined 2004
i'd like to give a boost to this thread,

i can't wait to hear the results of jens prototype :smash:

while looking for appropriate heatsink for this board, i found MF12-151.5 from Conrad heatsinks Australia.

jens, will 120mm x 151.5 be enough ?

My usage is outdoor PA so i'd be better with fan.

Since jens provided option for separate supply feed for front-end and outputs, i'll adopt A75 power supply to use 65-0-65 trafo.

Is it only the zener diode which needs to be changed ? if so, to what voltage rating ?
 
TonyTecson

TonyTecson

Member
Joined 2003
too good an amp to use for PA imho

hi roland,

the leach super amp is a high fidelity amp, no one can prevent you if you want to use it for pa. but i feel there are other amps more suitable for pa work, you can visit delta-audio.com any you will see what i mean.

i have the original design using to-3's, i can send you the files if you want them.

tony
 
BobEllis

BobEllis

Member
Joined 2003
...
My usage is outdoor PA so i'd be better with fan.

Since jens provided option for separate supply feed for front-end and outputs, i'll adopt A75 power supply to use 65-0-65 trafo.

Is it only the zener diode which needs to be changed ? if so, to what voltage rating ? [/B]
Click to expand...


Conrad also has heat sinks suitable for forced air - see flat back narrow fin spacing. Place two fin to fin and they make a nice tunnel for 120mm fans.

The A75 regulator multiplies the voltage reference by ~5.5. I got 64.5V out of it using nominally 12V zeners. You should also change the voltage divider resistors (R5, R8, R10 and R13)to 1/2 or 1 watt types, since dissipation is around .3 W in the 10K at 65V. If you use the LED, R15 and R16 should also be 1 W.
 
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