What preamp should i build for my 3886 GC??Tube?MOSFET?OPAMP?Bipolar?? - diyAudio
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Old 21st July 2005, 05:36 AM   #1
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Unhappy What preamp should i build for my 3886 GC??Tube?MOSFET?OPAMP?Bipolar??

Hi Guys!!I have finished build my 3886 GC.Then, i think to build a preamp to accompany my GC.But i have some question:
1. Do i need to add an active preamp??
2.What is the suitable preamp for my GC??I got many option from tube preamp (using 5687/12AU7 etc), using OPA2134/627/AD823 or using a mosfet, im confused to decided the best preamp should i build.
3. I thought to use a MOSFET preamp,as i know, MOSFET has a characteristic between tube and bipolar transistor,is it right??
4. If i use a tube preamp, can it give a 'warm' sound to my GC, and my GC has a'WArm' sound?
5. Is it useless or not, if i build and use tube preamp,but the power amplifier using GC,not MOSFET amp or TUbe AMP??
THX for ur attention. I hope, i can decided to build a preamp
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Old 21st July 2005, 08:13 AM   #2
Nuuk is offline Nuuk  United Kingdom
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Either build Pedja's Jfet buffer or the three-transistor buffer shown on Decibel Dungeon.

If you want to build a valve buffer because you like the sound, I suggest asking on the Valve forum.
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Old 21st July 2005, 08:40 AM   #3
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Aha...Mr.Nuuk thx for your answer. But my GC is not inverted version but Non inverted version, so it doesn't need a buffer.
Do you have other suggestion for me??
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Old 21st July 2005, 10:23 AM   #4
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What is a pre-amp? It is a means of controlling the volume, selecting a source and providing either some gain or some 'isolation' between the source and power amp (and 'driving' the interconnects between pre-amp and power amp).

That gain stage, or 'isolation' is the same as a buffer, either with, or without gain.

Yes, an inverted GC benefits more from a buffer but both types benefit from a prior active stage!
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Old 22nd July 2005, 06:16 AM   #5
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u are right, Mr. Nuuk. I think that a buffer used to keep the impedance in input. So, i want to build a preamp with a gain stage,not only for volume (pot) and selector only. I want to build an active preamp, which can give a sound extensions and give a line level. If i use a tube, maybe i can get a little 'warm' sound, can it be??
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Old 22nd July 2005, 06:33 AM   #6
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Or, i just need to build a buffer with a tube/jfet/OPA??
How about to build a buffer from OPA 2134??Is it good??How about the sound??How much gain should i build to match with GC??
I'm very confused now
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Old 22nd July 2005, 07:23 AM   #7
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Quote:
How much gain should i build to match with GC??
All these issues have been covered many times on this forum. It may require a lot of reading but remember, the more effort that you put into something, the more satisfaction you will get out of it!
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Old 23rd July 2005, 08:43 AM   #8
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Hi , Mr Nuuk . Thx for ur attention
I have a problem with my GC, about low input level from my cd player through my GC's input. So,when i open the pot volume until full, it's like 20watt amp (can drive the loudspeaker loud enough). But, i try my GC with my friend's preamp(tube and solid state) and i feel this true 60watt power amp. My GC drives the loudspeaker well.
So, do i need to used a preamp to get some gain???
Or, i just need to build a buffer???
Thx
Please help me!!!!
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Old 23rd July 2005, 10:04 AM   #9
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When an amp is driven 'properly', it gan give the impression that there is more gain.

Now look at this way. The major part of a pre-amp is the PSU. So build a (unity gain) buffer to try with your GC and see how it sounds. If you feel that you still need more gain, just change the unity gain buffer for one with some gain. You can even build an opamp buffer where you will only need to change the resitor values to alter the gain!

Unless of course, you want to go with a valve pre-amp but as I said before, you need the vlav eforum for advice on that.
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Old 25th July 2005, 09:36 PM   #10
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Try Carlos's pre-amp using a opa627 and buf634.
I've done that with a phono pre amp board and
a switched Holco H8 relay ladder for volume.

I use a gain of 5 as an option for the higher volumes.
This was necessary for low output sources like my
DVD player playing movies.

It's all remote controlled. The sound is excellent.

Harry
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