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Old 22nd July 2012, 05:50 PM   #1
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Default Help Me, How to make Pre-amp using 12AU7 tube and Op-Amp Ic mix?

Hi
i try to make preamp using 12au7 tube mix together with Opamp Ic lme49990, i need some help or recommend or schematic, do anyone try this before?
thank you
Tommy
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Old 22nd July 2012, 06:15 PM   #2
Fenris is offline Fenris  United States
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Why use both? Novelty? If so, try the second circuit down here:
SuperTriodes & Inverted ES Speakers
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Old 22nd July 2012, 08:00 PM   #3
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The fact is that preamps are more or less obsolete except for a few situations:
- gain is needed (everything is already line level) to drive a low sensitivity amp or long cable (low Z output required then)
- switching is needed (that can be done as a passive unit)
- tone control is needed (build one?)
- volume control - this can be passive, unless gain is required (rare)
- buffering needed - then no gain required.
- phonograph input wanted - build a phono stage with line level out?

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Old 22nd July 2012, 08:15 PM   #4
Merlinb is offline Merlinb  United Kingdom
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If you just want to play around with triodes as a musical effect, rather than proper hifi, you might find something useful in this article:
http://www.freewebs.com/valvewizard2...s_Blencowe.pdf
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Old 22nd July 2012, 10:38 PM   #5
Cassiel is offline Cassiel  Libya
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More about musical effects:
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Old 23rd July 2012, 07:50 AM   #6
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@Fenris, coz' i want get some sweet-n-warm sound from the tube but also i want to get some micro-details on the tops freq so why isn't to combine it together?

@Bear, thank's, but i don't want the phonostage(coz i don't have one n only cd-player)

@Cassiel and Merlinb, thank's a lot for the schematic and the artickel, i will try it
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Old 23rd July 2012, 10:20 AM   #7
DF96 is offline DF96  England
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If you want "sweet-n-warm" wouldn't it be better to simply make a cup of tea?
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Old 23rd July 2012, 10:57 AM   #8
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What sort of thing are you after, just a buffer, or a preamp with gain and a volume control?

Theres no point adding the op-amps to get 'micro details' as you have what's basically an open loop signal chain; which means that any additional active devices will cause further degeneration.

If I were you I'd use a 100K pot stuck on the input, use the tube for gain (something like 10dB is about standard for preamps which have a line level input) and then buffer the output with a MOSFET going into a CCS.

P.S. I find hot chocolate to be sweeter and warmer than a cup of tea, with the added advantage of being far smoother.
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Old 23rd July 2012, 02:14 PM   #9
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Quote:
Originally Posted by tommy thong View Post
Hi
i try to make preamp using 12au7 tube mix together with Opamp Ic lme49990, i need some help or recommend or schematic, do anyone try this before?
thank you
Tommy

Hello Tommy,

Maybe you try this circus 真空管緩衝前級(X10D-GC), there has PCB layout also.
This is a Taiwan people designed the tube buffer, just place the buffer between the CD player and preamp, the purpose exactly what you want.

I had bought the kit from there but did not finish, so I cannot tell you the result,
but heard a people said the sound has get warm when use it.

Ben
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Old 23rd July 2012, 02:48 PM   #10
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Here the link
真空管緩衝前級(X10D-GC)
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