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Old 4th February 2003, 06:22 AM   #1
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Default counterpoint sa-7(volume pot value)

Hi,I recently purchased a counterpoint sa-7 pre amplifier.I have decided to change the volume pot but i am not shure of the correct value
Any imfo or thoughts would be great
Also any other mods to this pre amp that could be done Thankyou
Ian
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Old 4th February 2003, 10:56 AM   #2
EC8010 is offline EC8010  United Kingdom
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Default Re: counterpoint sa-7(volume pot value)

Quote:
Originally posted by croft
Hi,I recently purchased a counterpoint sa-7 pre amplifier. I have decided to change the volume pot but I am not sure of the correct value.
Why do you want to change it? The value will probably be written on the body of the pot. Typical valve value is 100k log. You can measure it with a DVM, but you might need to desolder it first.
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Old 4th February 2003, 11:40 AM   #3
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Default pot

from my schematic the pot is a dual 100k audio
taper (logaritmic)

Reinhard
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Old 4th February 2003, 12:06 PM   #4
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Default SA-7.

Hi,

The SA-7 has indeed a dual 100K pot from ALPS.
A stepped L-attenuator would be a great improvement but I don't think there's all that much space to fit it inside.

If you want to upgrade this unit I would recommend trashing the Wondercraps and putting in some high-Q polyprops or styrenes instead.
MIT Multicap would be my preferred choice.

The resistors are mostly Resistas from Roederstein and Dale,these should be fine.

This preamp suffers from microphony though,so you will want to isolate it from floor and airborne vibes.

Cheers,
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Old 4th February 2003, 12:12 PM   #5
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Default WONDERCRAPS!!!

Hi Frank,

Was that a deliberate Freudian slip?

I fully concur with using MITs, and find the RTXs (like you, I believe) to be way better than their 'lesser' series, provided there is sufficient space to fit them in, and suitable values are available.

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Old 4th February 2003, 12:20 PM   #6
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Default YOU WONDER?

Hi,


Quote:
Was that a deliberate Freudian slip?
I can't type properly...

Quote:
I fully concur with using MITs, and find the RTXs (like you, I believe)
Correct.
Fortunately there aren't all that many caps to upgrade and even the MIT popyprops would be a nice upgrade already.

From memory,I think the original ones were rated at 200-250 V so that would be O.K size-wise.
Some drilling on the PCB will be necessary to pass the thick leadout wires of the MITs though.

So careful before you short some traces on that soundboard...err...PCB.

Cheers,
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Old 4th February 2003, 12:32 PM   #7
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Default Soundboard!!

Your typing is getting worse, Frank, you'll have the thread police onto you.

Regards,
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Old 5th February 2003, 03:29 AM   #8
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Default Re: Soundboard!!

Quote:
Originally posted by Bobken
Your typing is getting worse, Frank, you'll have the thread police onto you.

Regards,
Wot's all dis den?

Tim (Deputy of the Apostrophe Police on alt.binaries.schematics.electronics )
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Old 5th February 2003, 09:34 AM   #9
Bobken is offline Bobken  United Kingdom
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Default Re: Re: Soundboard!!

Quote:
Originally posted by Sch3mat1c


Wot's all dis den?

Tim (Deputy of the Apostrophe Police on alt.binaries.schematics.electronics )
Hi,

Not sure if your question is serious or not, but it relates to post #6 in the "Listening tests" thread.

Whether I bored a thousand readers or not, I did spend over 30 mins, late at night, trying to offer some helpful advice, whereas most of what this poster had already said was rather negative, and of no practical help to a 'novice', at all. It appears that the originator of the thread found my comments interesting, anyway.

Incidentally, I appreciated your post # 54 in "The Silly Question" thread, a point (one of many!) which I had also noticed amongst the efforts to discredit my comments, but, as with all the other incorrect remarks, it wasn't worth my time in referring to it.

I was interested in your own experiences about casting as I have done some of this (a long while ago), especially of the 'lost wax' variety. This was when I worked in the silver/jewellery trade, and I found it fascinating.

Am I right in assuming that this is an interest of yours, rather than your means of livelihood?

Regards,
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Old 5th February 2003, 10:45 AM   #10
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Wink Hi to everybody(great imfo)thanks+

Hi,Thankyou to all of the people who posted some great imfo regarding the counterpoint sa-7 pre amp that i have.

The value pot ratings are very usefull, Also the the cappacitor issue.

I had the idea of replacing the volume control after reading many hi-fi magazines articles and also noticing the differnce one made when i had an Audio research pre amp.I have seen some very cool Alps pots from Japan at 300+ These look awsome and apparently sound fantastick.
I believe that counterpoint volume pots were pretty basic in the early desighns.

One are that i have yet to try is running a pre amp on batteries instead of the mains outlet. I have seen maplin electronics sell small heavy duty motorcycle batteries that can be recharged,I believe that Unison research did a valve pre amp that had small watch batteries that heated the valve elements.
I think that this technology is not exploited enough

Thanks also for the issue of michrophony in this pre amp,I have got some valve rings which i will place on the valves,Manybe there are many other options to cater for this sort of thing

Thankyou fellow audiophiles
Ian.
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