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Old 10th May 2013, 11:13 PM   #111
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See attached.
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Old 11th May 2013, 08:27 AM   #112
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ahh, there it is, the missing grounding.....thanks!

and now... the resistors
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Old 11th May 2013, 09:19 AM   #113
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are these values correctly 'interpreted' ?

edit...R2 and R4 hanged, and I hope correct now

is P1 really only 500ohm, or is it 5k ?
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Old 11th May 2013, 11:28 AM   #114
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R2=22.1K, R4= 22.1K, R6=33.1, R8-9=4,75K, R13=68.1, R14= 6.81K, R15= 1.5K, R15-16=10.1, R34=3.3.
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Old 11th May 2013, 01:35 PM   #115
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R14 corrected....

thanks!
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Old 11th May 2013, 02:06 PM   #116
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wouldn't we want to add a bypass cap across C5/6 and Z1??
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Old 11th May 2013, 05:18 PM   #117
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for 'convenience', and layout, my usual exercise....drawing to get 'familiar' with the components ....and I hope its still the same amp
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Old 11th May 2013, 05:52 PM   #118
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I will have to presume that the diode string across the bases of TIP 142 147 will shunt excessive drive to output and that will create a crude method of limiting if and when needed

I am actually not familiar how protection like that will work sound wise ...None of the amplifiers i am listening to had this schema of protection ...Also don't know how effective this is

Then the question for me is :why bother? since Darlingtons on the output will do there "own" thing after the protection depending on the thermals cooling load and so on and on .

Tinitus i think exercise is always nice and sharpens brains but i think one may put his energy on a pcb and not a schematic .

Nice idea for a weekend project could be a pcb that has the arrangement of transistors L style bracket made like NPNPDVBEDNPNP
Where
N stands for NPN
P stands for PNP
D for driver ( there can be a question if driver needs common heat sink with outs)
and VBE will be Vbe

could be nice project but not for me ...unless one has a better darlington to offer than 142 147 ( any with audio specs will do )

I presume that arrangement like that will offer excellent current sharing and equalize thermals all the way through . Point is no matter what i say the next step is to construct and listen cause i may hate darlingtons while NP operates them in an ""other" way and after all may worth listening .

Kind regards
Sakis
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Last edited by east electronics; 11th May 2013 at 05:59 PM.
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Old 11th May 2013, 07:35 PM   #119
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Quote:
Originally Posted by Nelson Pass View Post
A few quick answers.

The original design (this one) was intended for dummies with maximum
reliability and minimum adjustment and also minimum opportunity for
noises and pops. ....

I guess that answers it .... maximum reliabity sounds good for my bass guitar... and intended for dummies, spot on too

I expect to hardwire on proto board

regarding the Darlingtons
with their high current gain, I suppose they are easy to drive, and might have been chosen for that reason ?

http://www.onsemi.com/pub_link/Collateral/TIP140-D.PDF

I guess there is a first time for everything, also on Pass forum
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Old 12th May 2013, 10:53 AM   #120
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ZTX450/550 'replacement' might be BC546/556
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