John Curl amp

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MikeW

MikeW

Member
Joined 2002
MikeBettinger said:


Hi Mike,

I'm curious as to how the form for your layout came about. Seriously. Is this the way you've layed things out in the past, is there a applications note or book that suggests this, or do you have a heatsink that fits?

The reason I ask is #1 you asked for feedback and # 2 with this layout the most sensitive parts of the design, ie the signal path, are making the longest runs.

If you've had good results I'll say no more and if there is sound logic I'd be interested, as I'm a layout info fanatic (not really, but that sounds dangerous ;) ). Anyway, I'm actually curious because I see this form factor in many of the design pics posted here and I'm interested mainly because I do things differently.

Regards, Mike.
Click to expand...

I work for radio company. Mostly higher frequencies. The guy who lays out the board does these. It costs a few buck plus a Le Monstre. I didn't think the signal path was that long. The feedback loops are. There is an output plane under the big emitter resisters. We will see what happens when I build it. I am glad you looked at it. Did you see any problems? I think I need to make R24 a 2 or 3 watt.
 
MikeW

MikeW

Member
Joined 2002
1 st parts list

R1 1 Meg
R2 220 ohm
R3 10 ohm 1 watt
R4 10 ohm 1 watt
R5 10 k
R6 1 k
R7 .1ohm 3 watt
R8 .1ohm 3 watt
R9 10 k
R10 can't find
R11 1 k pot
R12 5 k pot
R13 10 ohm 3 watt
R14 10 ohm 3 watt
R15 .1ohm 3 watt
R16 .1ohm 3 watt
R17 10k
R18 1k
R19 220 ohm
R20 10 ohm 1 watt
R21 10 ohm 1 watt
R22 1 Meg
R23 80k
R24 10 ohm 2 watt layout needs to be changed.
R25 500 ohm pot

C1 5 uf
C2 100uf
C3 5 uf
C4 5 uf
C5 5 uf
C6 100uf
C7 .1 uf
C8 set @ test (a couple of pf)

L1 2uh

U1 2sk389
U2 2sj109
Q1 BD140
Q2 BD139
Q3,Q4 MJL 3281
Q5 BD139
Q6 BD140
Q7 BD140
Q8,Q9 MJL 1302
Q10 BD139

Updates welcome. Thanks, Mike.
:devilr:
 
john curl

john curl

Member
Joined 2003
I 'might' quibble, but what you are doing looks pretty good to me.
Back in 1970, we were trying to make the same prototype,(with bipolar transistors on the input diff) and we hired Jim Furman as a tech, to build it. He made it COMPLETELY non symmetrical, and I never used him again for this kind of thing. He later got rich making Furman Sound, still we never got along. I still respect his ability.
 
M

MikeBettinger

Member
Joined 2006
BettingerAudioDesign.com
john curl said:
I 'might' quibble, but what you are doing looks pretty good to me.
Back in 1970, we were trying to make the same prototype,(with bipolar transistors on the input diff) and we hired Jim Furman as a tech, to build it. He made it COMPLETELY non symmetrical, and I never used him again for this kind of thing. He later got rich making Furman Sound, still we never got along. I still respect his ability.
Click to expand...

There's a bit more to layout than being symmetrical or looking good :). When the discussion can postulate as to the DA of a soldermask affecting the sound (or not) it seems odd that a (rather large by comparison) physical attribute might be so simply satisfied :xeye:.

Mike.
 
dimitri

dimitri

Member
Joined 2002
I couldn't see separation between input ground and high current ground
There is no resistor between 5uF and 100uF in each reail
The loop C2Q3Q8C6 is very large
R24C7 - what is it - Zobel? Why elco? Completely wrong place for Zobel
Don't use ground plane for current flow
Where is resistor in each base of output BJT?
Bias setting transistors are too far from the output
...
Sorry, Mike
 
MikeW

MikeW

Member
Joined 2002
dimitri said:
I couldn't see separation between input ground and high current ground
There is no resistor between 5uF and 100uF in each reail
The loop C2Q3Q8C6 is very large
R24C7 - what is it - Zobel? Why elco? Completely wrong place for Zobel
Don't use ground plane for current flow
Where is resistor in each base of output BJT?
Bias setting transistors are too far from the output
...
Sorry, Mike
Click to expand...


1. I do need to spilt the ground plane.
2. Not on schematic
3. See post 303
4.It is part of the feedback loop.
5. See # 1
6. Not on schematic
7. They are to be mounted on the heatsink from the bottom of the board. This is a class A amp. The heat should remain constant after warm up.

Thanks for the input, Mike
 
MikeW

MikeW

Member
Joined 2002
MikeW said:



1. I do need to spilt the ground plane.
2. Not on schematic
3. See post 303
4.It is part of the feedback loop.
5. See # 1
6. Not on schematic
7. They are to be mounted on the heatsink from the bottom of the board. This is a class A amp. The heat should remain constant after warm up.

Thanks for the input, Mike
Click to expand...

# 2and # 6 now on schematic. You can jump them if you don't want to use them.
 

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dimitri

dimitri

Member
Joined 2002
see below
 

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