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Old 3rd April 2009, 02:20 AM   #11
picopos is offline picopos  Portugal
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hey sakis
i've been reading around here,a bit of everything...and it's getting much more complex h h
can you help me here?
1991 amp,no pre,i drive it with audio interface pc based,heavy work in all these years,'s not really a vintage but....
Is it possible to recap with capacitors other then electrolitics,all of them(maybe not all on the power supply)...let's not think on cost or boutique's,only usefull and quality...???????????
i can give more details if this is ever good sense in your opinion...
i really like this amp,it's not a top notch amp,most probably it's ab,i dont know,i think i even have the shematics,not sure...but latelly is getting desapointing,and i'm noticing it changing in a short period of time,it got worst in the last 2 months,and based on what i have been reading i really think it's time for caps and so why not better then elect....

what say your experience?
thank you

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Old 3rd April 2009, 07:13 AM   #12
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Default if i understand well

you would like to replace all caps in one amplifier in a patern tha NO electrolytic exist inside .....( except ofcourse power banks )

i have just a few things to tell you

from default there is circuits that work like that : have no electrolytics in the signal or feedback path might consider using a thing like that

doing a replace like that might be not possible since there will be a size issue ( mkt caps will have huge size compaired to electro's)

then again huge componets like that might also work as antenas and then the same design might not work well after changes like that ( may other layout required )

finally ....

place a schematic of your amplifier

in general a few other tweeks can be applyied to make your amp a lot better and still use elctro's

----- bypass with good quality film caps
-----change resistors to metal film
----- play with VAS miller cap
-----play with input filter
----- upgrade caps to a better quality
----- shift idle
----- play with zobel
----- rewire critical things
----- shift safety margins to next level

all the above will make a very nice amp without repalcing the electro's
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Old 3rd April 2009, 10:29 PM   #13
picopos is offline picopos  Portugal
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great sakis(i feel like i'm learning something here)
will it be fine to post the scheme here?????give me some time to do that....
i rewired some parts(eliminate a/b switching and phones output as they are resistors for that not a dedicated amp and the switch in that plug wasn't very trusty),i think almost all resistors r metal film,but the quality of the caps i'm not sure,and besides with all the hours on my opinion it's a very simple amp,not many components per channel....
this is one of the things i would like to do and next i would like to clone this amp but with mods...let's see if time allow's it...

thank u for ur precious time Sakis

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Old 4th April 2009, 11:28 AM   #14
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Default yeap !!!!!

thats the spirit !!!!!

go ahead

but please post the schematic in a new thread and keep me posted about

also others may have some more suggestions

feel free to email me for any assistance

regards sakis
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Old 25th June 2009, 10:11 PM   #15
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Default greeeeaaate!!!

Lots of very useful information here sakis, thanks for the link.
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Old 8th January 2010, 05:30 PM   #16
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Talking YouTube

Originally Posted by destroyer X View Post

Wow! Great videos and photography on your YouTube site!
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Old 8th January 2010, 07:19 PM   #17
a.wayne is offline a.wayne  United States
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what about upgrading driver transistors . Say i wanted more amps from driver stage can i upgrade to beefier transistor , if so what about the Bias ?
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Old 8th January 2010, 07:51 PM   #18
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Default They're not great, i feel ashamed with them, but they are the best my camera

and freeware software can do.

Thank you anyway, very kind from you to call that great.


Full throotle amplifier manufacturing;, Sample Dx Classic
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Old 8th January 2010, 09:51 PM   #19
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Very interesting.

Here's what I've done -- remove the entire driver section, pcb and all and sell it on EBay -- substitute with LM4702, LME49811 etc. I've just been tickled at what the driver board for a 1970's vintage Pioneer receiver will fetch. 1970's vintage receivers are my favorite -- there's plenty of room, enormous heat sinks, good power transformers, AM and FM tuner sections at the peak of their performance etc., etc.
Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?
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Old 9th January 2010, 07:41 AM   #20
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often the approach of restoring is bring a machine to life and if possible to original condition ....

answer to your question will be that yes there is always going to be a margin for playing arround with bias , drivers and outputs , but as a rule i would say that everything is possible but for sure will have an effect at the safety margin of your amplifier ...

so changes are to be made with caution and doyble veryfied with instruments

-total recaping ,
- proper tuning (idle offset) multiturns here and there
-total removal of ceramics and re with s mica or styroflex or multileyer
- mechnaincal ( paste and cooling )
-thermal joints in the ltp
-film resistors where needed
-relocation of zobel
- bit of rewiring
- and a bit of caution in input caps and VAS miller cap
and a bit of here and there will alter the performance dramatically of the amplifier without effecting safety

beyond that all mods are possible but will require another approach

regards sakis
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