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Old 13th August 2008, 09:06 PM   #1
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Default Pre-amp component question

Hey everyone.

I built a simple preamp for a friend and have recently come into some Burson discreet op-amps. I tried it in my design and was very pleased.

I want to go "all out" building mine and with only 8 components it should not be really hard to do so.

It is just a simple non-inverting gain stage with 12dB gain. The only resistor "in" the signal path is the feedback resistor and I don't know if that even affects sound at all.

The original was built with rat shack .5w carbon resistors, a pair of 2pf silver mica caps bypassing the feedback resistor and an LM4562 as the gain stage.

Would a high-buck "audio resistor" matter in this circuit at all?
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Old 13th August 2008, 09:43 PM   #2
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All the resistors shown in the circuit are in the signal part and very audible. Are these caps essential for the Bursons?
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Old 13th August 2008, 11:54 PM   #3
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No, I had read that they help stabilize high frequencies.

What resistors would you recommend? I am kind of partial to carbon because I almost think metal film might be too harsh...the bursons are very very clean and precise.
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Old 14th August 2008, 12:30 AM   #4
lineup is offline lineup  Sweden
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There are no such things as 'audio resistors'.
Metalfilm resistors are known to be the best for audio.
Except for some very extraordinary circuits, which demands something that metalfilm can not provide.

Carbon or carbon composite resistors are not even used in tube amplifiers these days.
It belongs to when was no metalfilm resistors around = invented.

For a simple audio op-amp circuit, no matter if discrete or chip,
there is no use in experimenting with noisy carbons or anthing else but low cost standard metalfilm resistors (0.25 Watt / 0.6 Watt).

Unless you do not have a 'matching op-amp' full of noise
go for 'noise free' metalfilm.
(if your op-amp is noisy, there no big deal to use some strange resistors with increased noise level to please your listening experience)
------------------


You are probably giving your self some headache you do not need to have, man.
Resistor does not produce anything we can hear and call 'harsh'.

More probably you will hear your Headphones or your Speakers.
These are the ones that can produce sound.
At least in my Lineup Book of Audio


If your Burson is clean .. do not make it dirty, please!


Regards Lineup
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Old 14th August 2008, 12:35 AM   #5
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I was referring to Rikens which were supposedly made for audio...

Ok, will do on the metal resistors...thanks for reassuring me that cheap is fine.

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Old 14th August 2008, 06:54 AM   #6
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Quote:
Originally posted by billnchristy
thanks for reassuring me that cheap is fine.


It's fine if you can't afford better.

The only carbon films i can tolerate are the Rikens. Still, without actually trying them with the Burson modules there is no telling what is best, my point was that all resistors shown are equally important.

Unless Burson recognises problems with stability i would not use any compensation caps, even a ridiculous value as 2pf.

What may be more important for your modules is to provide some PS decoupling to ground. Have you thought about that?
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Old 14th August 2008, 07:01 AM   #7
Mooly is offline Mooly  United Kingdom
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Quite a few years ago now a preamp by Reg Williamson in Wireless World (from memory) was constructed in two versions for a comprehensive double blind listening test. One was built from "audiophile" parts and the other from "commercial" grade components, sockets etc. There was no statistical difference.
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Old 14th August 2008, 12:57 PM   #8
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What about crazy metal foil resistors with .01% tolerance? Worth the cash?

Something like:

http://www.newark.com/35H5064/passiv...s102c-10k-0-01
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Old 14th August 2008, 04:58 PM   #9
Mooly is offline Mooly  United Kingdom
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Of course it's worth it
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Old 14th August 2008, 05:33 PM   #10
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Quote:
Originally posted by Mooly
There was no statistical difference.


That's cool. I am only really interested in my own perceptions
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