What preamp should i build for my 3886 GC??Tube?MOSFET?OPAMP?Bipolar??

:smash: 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 ;)
 
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! :att'n:
 
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??
 
Hi , Mr Nuuk . Thx for ur attention:smash:
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!!!!:bawling:
 
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. ;)
 
Actually i found that my pot's true value is 80k not 50k(label) so this pot give a big load to my cd player. Then, i change the pot to 50k and this amp can drive the loudspeaker properly.
ACtually, the cd player's output is 2 Vrms .So, we can say that we don't need a preamp as a line level stage. But i still found, many audiophiles use a preamp for listening music,it's so weird,isn't it???? Or, many audiophiles use passive preamp which don't provide gain stage???
:D
Actually, i just want to give some sound colour to my GC by adding a preamp. Because i found some people said, my GC doesn't have a good deep sound ,dynamic sound and emotion sound. :bawling:
My opinion about this combination:
1.GC+bipolar transistor preamp------->sound become a little rough,still doesn't have deep and emotion, but dynamic sound appear.
2.GC+tube preamp----------------------->sound become a little noise but natural noise, smooth, the deep,dynamic and emotion sound appear.
So, my conclude is tube preamp can give the best sound to my GC.
Any other opinion???:angel:
 
Helo thomgun,

try to use lower pot (like 20K or even 10K)... and hear it...

FYI, I think GC is quite transparent... and neutral... it is not a sweet/syrupy sounding amp...

One way to colour the sound is by changing the output cap of your cd player (if it has). Change it with some polypropylene brand or paper in oil... it might be sweeten the sound...

REgards,
---
David
 
The sound of an amp depends on may things.
Not the least what speakers it's driving it.
It depends on the speakers impedance,
the flatness of the impedance curve and
the size of the coils.

I find the chip amps work the best at 8 ohms.
If you use lower impedance speakers they
may need parallelling. The same may be true
for larger woofers.

I find that the resistors in the feedback loop
change the sound quality a lot. I like Vishay
foil and Holcos H8.

I just changed from tube gear to chip amps.
I find that the tubes sound great at a single
tone at the time, but for complex music the
intermodulation distortion blurs the sound.

I prefer the sound of op-amps because of the
higher detail level.

Harry
 
:eek: I see. But i still don't know how to measure my GC input sensitivity. I realise that CD player have 2Vrms output, so we must match the input level to GC. But i think, we don't need a preamp, but i still want to give a sound colour to my GC ;) .
I try to change input resistor with Dale and it sounds good with a log potensio. When i use a cheap lin pot, sound become harsh and bad, so i try to use other pot. My input cap use 400V (a little big the brand is "SPIRIT"), and the other cap is MKM and use metal film resistor.:rolleyes:
Then i thought, how about increase the gain of GC from 23x to 40x??Will be sound good or poor???Need ur opinion please.
My GC use non inverting system, then i thought, how about build a buffer with 6922 tube??:xeye:
 
:angel: dwinarso, can i PM u???
H_andree u said that opamp sounds good than tube, i agree with u if we use this GC with a dynamic music, but tube has a warm sound and smooth sound if we listen slow and vocal music, and a tube have a emotion sound depend on tube characteristic and have a good deep sound. :dodgy:.
I still think, how to improve my gc to provide more dynamic sound, have a deep and emotion sound, can anyone help me??:hot: :smash:
 
Listen.

I was one of the biggest advocates of tubes. There are many
good tube amps out there. I was at a show and I liked
the VTL mono blocks ($40k pair). I liked the Pathos
amps (Hibrid tube stage mosfet out) ($10k). I also liked the
sound of the Conrad Johnson.

A well build pre-amp based on the opa627 can produce
just as nice of a sound.

Tubes inject 2nd order harmonics. This sounds like an increased
reverb on vocals. On larger pieces this takes away detail.
I think now although you may like the sound of tubes it may
be not as accurate. I always found the sound of solid
state to be grainy and sterile.

I use Vishay foil resistors on the pre-amp and Holcos outside
the signal path. I used black gates on the voltage pins.
I use a double regulation: From 18 - 12 - 9 V. I use 68000
uF on the power supply. Believe me the sound is exremely
good. You'll be hard to press to find a better pre-amp.


It's your choice.

Harry