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Old 11th July 2003, 10:28 PM   #11
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Quote:
Originally posted by analog_sa
You may be keen to learn that tight layout and better wire have absolutely no effect on offset.
if resistors from different batches and isolation pads can have audioable impact on sound, it would only be natural to see the same for pcb layout and better wires.

Next thing you know, people are going to claim that the use of Honda lawnmowers two towns over will make their amps sound nice, airy and open open the soundstage,
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Old 11th July 2003, 10:30 PM   #12
ronc is offline ronc  United States
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All i use is battery P/S. One time , just for grins and giggles, i made a 3 component amp.10k res-300k res and the chip(no caps anywhere).pin 7 went straight to ground.It worked very well but i felt the need for more control and the offset was higher than i really wanted (.028 v) And not having a cap on the input makes me a little nervous.Of course it had to have a pre.
ron
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Old 12th July 2003, 08:07 AM   #13
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Quote:
if resistors from different batches and isolation pads can have audioable impact on sound, it would only be natural to see the same for pcb layout and better wires.
Milwood

You are missing the point entirely. Of course pcb layout and wires have a profound effect on sound but not on offset. If you think this is very funny you're certainly entitled to your opinion. How ironic that people with no interest in sound choose audio as a hobby.

peter
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Old 12th July 2003, 11:15 AM   #14
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Quote:
Originally posted by analog_sa


Of course pcb layout and wires have a profound effect on sound but not on offset. If
peter, are you sure on that? what if the pcb is leaky, the wires got too close, etc.?
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Old 12th July 2003, 01:50 PM   #15
ronc is offline ronc  United States
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All i use is p2p wiring.Never will ave a problem if you are careful.I believe analog is correct.
I use a 500k multi turn trimmer between pin 7 and ground to corrct for offset.If the amp has been run in and normal operation temp. i just dial in the offset.I have found out that it will drift slightly but only about .001v.
ron
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Old 12th July 2003, 04:44 PM   #16
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Quote:
peter, are you sure on that? what if the pcb is leaky, the wires got too close, etc.?
Yes, i am positive. No amount of pcb leakage or closeness of wires will introduce measurable change in offset. While the pcb leakage (gigaohms?) may in theory have an effect (microvolts?) the closeness of wires is absolutely irrelevant.

cheers
peter
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Old 12th July 2003, 04:57 PM   #17
fender4 is offline fender4  United States
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I learn something new every day! I just assumed that the change in offset was due to the new layout, but after some reading, analog_sa is correct in that this probably didn't have any effect on the offset.

I know I'm not an electronics expert. I just like simple projects like this to "learn through experience".

Ron, I think I might try the trimmer pot idea. I would feel much better about trying new (other's) speakers with a minimized DC offset. (Sorry analog_sa, no Lowthers...yet ).

-f4
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Old 12th July 2003, 05:58 PM   #18
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Quote:
(Sorry analog_sa, no Lowthers...yet ).
I don't think i'd ever go back to Lowthers; informative and fast as they are, the price is incredible headache after even a short listen. Even with PX25 SETs. I wouldn't mind using a pair just to audition amps, passive components, cables etc; for music: no thanks. Others certainly disagree.

cheers
peter
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Old 12th July 2003, 08:20 PM   #19
ronc is offline ronc  United States
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Heard lowthers before, an acousta cab wih 300b set amps.Yes the sound was dang good , fast and all but no bass to speak of.
At present i am using fostex Fe103e horns (my own design) and combined with the GC the sound is fanstastic. although i am forced to admit that SPL is limited in the small fostex.
ron
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Old 14th July 2003, 11:41 AM   #20
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Quote:
Originally posted by ron clarke
All i use is p2p wiring.Never will ave a problem if you are careful.I believe analog is correct.
I use a 500k multi turn trimmer between pin 7 and ground to corrct for offset.If the amp has been run in and normal operation temp. i just dial in the offset.I have found out that it will drift slightly but only about .001v.
ron
500k seams too high, you'll have difficulty in tuning for 0mv.
I use 50k multi-turn trimmers and can easily get 0.00 mv.
Although I don't have a top of the range multimeter, it will not be far from the 0mv mark.
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