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Help Me, How to make Pre-amp using 12AU7 tube and Op-Amp Ic mix?

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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?

_-_-bear
 
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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
 
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.
 
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:confused:
Tommy


Hello Tommy,

Maybe you try this circus ¯uªÅºÞ½w½Ä«e¯Å(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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@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

Well the PDF was too big to post it here but I should have googled it in the first place. Here it is:

http://www.google.es/url?sa=t&rct=j...-cnkCQ&usg=AFQjCNHuLfO3STBjy_aUw_bDVxIvF4rULQ
 
You can't get "micro details" from an opamp by passing it through a tube or the other way around. It don't work that way.

You will get a composite that is dominated by the one with the greater audible harmonic distortion.

What you might want to try is a solid state (op amp) input buffer, with a level control in the middle (make that 10k-25k max) and then a tube buffer output to drive the cable. That is likely as good as you can do with an active pair like this.

One could put a bit of gain at either end, but I'd opt against that because you have CD output which is already plenty high enough level. Just play it straight out into your amp and see how loud that is. Do you want to play louder? then you need a few dB of gain.

Which then makes an idea to make switchable gain or switch in/out the input stage, depending on how you want to make that happen.


_-_-bear
 
by DF96"If you want "sweet-n-warm" wouldn't it be better to simply make a cup of tea?"

ha haaa...i prefer Starbuck's Hot White Chocolate Latte is more smooth than warm tea, friend

@Monty78pig, yeah ...i will consider that idea too..
@benchong, thank's...but looks like that kit is only tube buffer...it's not the one i want
@bear, yeah....i thought the same thing...like put opamp ic on gain preamp and put tube on buffer stage....i will try to put it together
@Cassiel.....wow...its good artickel to read and input
 
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