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Old 9th May 2004, 03:02 PM   #1
meo85 is offline meo85  Italy
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Question Minimal IC Preamp for my gainclone

Hi to all! I've build recently a gainclone on the first Peter Daniel's schematic and now I've thought to build an IC preamp for it.
I've got any OPA627, so this could be the IC which I can use.
Anyone can indicate to me a good schematic for this purpose (line preamplifier)?
Thank you to all, excuse me for my poor English...
bye bye, Matteo
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Old 9th May 2004, 05:35 PM   #2
Nuuk is offline Nuuk  United Kingdom
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With a volume control (and selector switch if you like) this will work very well!
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Old 9th May 2004, 05:57 PM   #3
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Quote:
Originally posted by Nuuk
With a volume control (and selector switch if you like) this will work very well!

I don't see a preamp there Nuuk? He already has a GC!
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Old 9th May 2004, 07:06 PM   #4
meo85 is offline meo85  Italy
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Yes, I already have a GC, with volume control... but I want to try a preamp for listening the differences (if there are)...
bye bye, Matteo
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Old 9th May 2004, 10:20 PM   #5
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http://www.decdun.fsnet.co.uk/gainclone2.html

http://diyaudio.com/forums/showthrea...5&pagenumber=1
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Old 10th May 2004, 08:59 AM   #6
Nuuk is offline Nuuk  United Kingdom
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What is a preamp?

It is a volume control and, if required, a selector switch.

It can be passive with just the above components or active which is what will make the difference with a GC.

To make it active, you can use a simple buffer circuit like the one used on my opamp buffered GC.

So you may not see a preamp on that page but with the addition of the contols, there is enough information to build one!
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Old 10th May 2004, 12:23 PM   #7
mAJORD is offline mAJORD  Australia
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well.. I tryed using my GC with no Preamp.. using line level (CD player) and with a gain of 20 it was no good, (as can be calculated)

not only that tho it sounded like **** .. BUT if there such a thing as running in the caps (im sceptical) , then that could have been the cause for the bad sound .



I was looking for a simple design aswell. but found nothing that wasnt 2 stage, I wanted to use a single LM833 . but in the end have ordered a PCB off ROD elliot sound here in australia, which includes balance and tone controls, and is 2 stage, ill use the 2 833s in it and see how they go first up.
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Old 10th May 2004, 12:31 PM   #8
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Well... with a passive pre you need a gain or around 30~33.
For a simple but veeeery good pre, OPA627.

Just don't use the LM833, or the whole thing will sound as a kitchen radio.
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Old 10th May 2004, 01:21 PM   #9
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Quote:
Originally posted by mAJORD
well.. I tryed using my GC with no Preamp.. using line level (CD player) and with a gain of 20 it was no good, (as can be calculated)
What supply voltage are you using? What is the output of that CD player? What is the sensitivity of those speakers?

A GC with at least +/-24VDC should move any speaker directly driven by any CD player.

Quote:
Originally posted by mAJORD
not only that tho it sounded like **** .. BUT if there such a thing as running in the caps (im sceptical) , then that could have been the cause for the bad sound .
Using at least 1000uF capacitors should provide plenty of bass. The minimum you should use are Siemens/Epcos caps.

Quote:
Originally posted by mAJORD

I was looking for a simple design aswell. but found nothing that wasnt 2 stage, I wanted to use a single LM833 . but in the end have ordered a PCB off ROD elliot sound here in australia, which includes balance and tone controls, and is 2 stage, ill use the 2 833s in it and see how they go first up.
Get away from the 833! At least use NE5532s, if you can't get any better. But there are many modern chips now that upgrade it. They are trickier to implement but sound better.

See if Rod's board provides some way to bypass the tone controls stage, and put a switch to do it. Balance control should be useful only on a very "unbalanced" room. If possible avoid it too.

Carlos
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Old 10th May 2004, 02:39 PM   #10
meo85 is offline meo85  Italy
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Quote:
Originally posted by carlosfm




Well... with a passive pre you need a gain or around 30~33.
For a simple but veeeery good pre, OPA627.

Just don't use the LM833, or the whole thing will sound as a kitchen radio.
I've some opa627 that I've never tried....
what schematic can I use?
Thanks!!
bye bye, Matteo
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