Need preamplifier schematic/suggestions

Jon the Grimm · 14th July 2010, 12:44 AM

I'm currently working on collecting the parts to make a power amplifier. I would like to simultaneously build a preamplifier, but as I know absolutely nothing about them, I need a schematic suggested to do what I want.

All it needs to do is enable my mp3 player to drive the power amplifier to full power, It should be very simple and use a single 6sn7 per channel. Bass and treble controls would be nice but not necessary. Anybody have info on what I am looking for?

Wavebourn · 14th July 2010, 12:49 AM

mp3 player can drive a pair of output tubes directly. What a clean sound!

Jon the Grimm · 15th July 2010, 12:23 AM

Pair = SE?? Will it work with a push-pull Williamson amp too? I just want to make sure because I read somewhere else in this forum that power amps typically need 1-2 volts rms and also that mp3 players may only put out .5v.

Miniwatt · 15th July 2010, 02:00 AM

I just designed -and put together- a 6SN7 preamp this evening, I switched it on not an hour ago. At first I was quite impressed, but it is clearly burning in, too early to make statements about the sound. I suspect the cathode capacitors are mostly to blame.
It's a SRPP btw, I'll post a schematic later if that's helpful.

Oh, and Wavebourn was joking..

Jon the Grimm · 15th July 2010, 10:20 PM

Very funny. I take it a preamp is necessary then?

Yes Miniwatt, I would like to see your schematic.

Wavebourn · 15th July 2010, 10:36 PM

Quote:

Originally Posted by Miniwatt

Oh, and Wavebourn was joking..

No, I was not.

If say EL84 needs 10V RMS on 200K grid leak resistor, what is the power?
Can MP3 player give much more? However, a matching transformer may be needed. But you can obtain them in EDCOR Electronics Corporation

One more option: 6J52P tube. No input matching transformer needed.

SY · 16th July 2010, 09:33 AM

Quote:

Originally Posted by Jon the Grimm

Very funny. I take it a preamp is necessary then?

No, it's not. The Williamson is more than sensitive enough to take a line output from an MP3 player. All you need to do is put in a volume control on the power amp, unless your player already has one.

Bandersnatch · 16th July 2010, 11:46 AM

hey-Hey!!!,
given the usual amp sensitivity, consider something with a mu of less than 10. Single triode tubes like 12B4 or 6AH4 or perhaps triode-strapped EL86. Knowing what the amp looks like would help a great deal.

Would that perhaps be Dr. Grimm?
cheers,
Douglas

soro · 05:04 PM

http://www.diysong.com/diysong/viewtopic.php?f=7&t=5002
it is my new preamp use 12AU7 or 6DJ8 and 12V single power supply.

soro · 16th July 2010, 05:02 PM

It is my new preamp it can be headphono amp.

use 12V single power supply.

14th July 2010, 12:44 AM	#1
Jon the Grimm diyAudio Member Join Date: Jun 2010 Location: Madison, WI	Need preamplifier schematic/suggestions I'm currently working on collecting the parts to make a power amplifier. I would like to simultaneously build a preamplifier, but as I know absolutely nothing about them, I need a schematic suggested to do what I want. All it needs to do is enable my mp3 player to drive the power amplifier to full power, It should be very simple and use a single 6sn7 per channel. Bass and treble controls would be nice but not necessary. Anybody have info on what I am looking for?

14th July 2010, 12:49 AM	#2
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	mp3 player can drive a pair of output tubes directly. What a clean sound! __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

16th July 2010, 11:46 AM	#8
Bandersnatch diyAudio Member Join Date: Jul 2003 Location: Ann Arbor, MI	hey-Hey!!!, given the usual amp sensitivity, consider something with a mu of less than 10. Single triode tubes like 12B4 or 6AH4 or perhaps triode-strapped EL86. Knowing what the amp looks like would help a great deal. Would that perhaps be Dr. Grimm? cheers, Douglas __________________ the Tnuctipun will return

16th July 2010, 04:58 PM	#9
soro diyAudio Member Join Date: Jul 2010 Location: Taipei	http://www.diysong.com/diysong/viewtopic.php?f=7&t=5002 it is my new preamp use 12AU7 or 6DJ8 and 12V single power supply. Last edited by soro; 16th July 2010 at 05:04 PM.

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15th July 2010, 12:23 AM	#3
Jon the Grimm diyAudio Member Join Date: Jun 2010 Location: Madison, WI	Pair = SE?? Will it work with a push-pull Williamson amp too? I just want to make sure because I read somewhere else in this forum that power amps typically need 1-2 volts rms and also that mp3 players may only put out .5v.

15th July 2010, 02:00 AM	#4
Miniwatt diyAudio Member Join Date: Nov 2004 Location: Den Haag	I just designed -and put together- a 6SN7 preamp this evening, I switched it on not an hour ago. At first I was quite impressed, but it is clearly burning in, too early to make statements about the sound. I suspect the cathode capacitors are mostly to blame. It's a SRPP btw, I'll post a schematic later if that's helpful. Oh, and Wavebourn was joking..

15th July 2010, 10:20 PM	#5
Jon the Grimm diyAudio Member Join Date: Jun 2010 Location: Madison, WI	Very funny. I take it a preamp is necessary then? Yes Miniwatt, I would like to see your schematic.

16th July 2010, 05:02 PM	#10
soro diyAudio Member Join Date: Jul 2010 Location: Taipei	It is my new preamp it can be headphono amp. use 12V single power supply.

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