Help with phono preamplifier selection - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th October 2003, 02:38 AM   #1
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Default Help with phono preamplifier selection

I just finished a PassDIY Pearl and need just a little more gain. Maybe 20dB or so. I am using an AN UK transformer to get it up to about the same level as the disc player and tuner. But would love to do it with active amplification. Do any posters have a simple circuit suitable as a moving coil amplifier.
I have single rail supplies, very quiet and around 20v available to power either a transistor or opamp. Looking for warm, full bodied, fast, dynamic, and quiet. Not asking for much.
The MM input is close to the jacks, the leads could be pretty short on both ends. Currently the unit is very quiet even with the transformer.

George
  Reply With Quote
Old 30th October 2003, 06:10 AM   #2
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Try 2 parallel 2sk170; drain - 1.2k, source - each 33R, whatever loading resistor suits you at the gate, 2.2uF output cap. Plays fine with 300uV carts and with NiMH batteries, tantalum resistors and MIT RTX output caps better to my ears than any transformer i've tried
  Reply With Quote
Old 30th October 2003, 10:32 AM   #3
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Quote:
Originally posted by analog_sa
Try 2 parallel 2sk170; drain - 1.2k, source - each 33R, whatever loading resistor suits you at the gate, 2.2uF output cap. Plays fine with 300uV carts and with NiMH batteries, tantalum resistors and MIT RTX output caps better to my ears than any transformer i've tried
Thanks, I will breadboard one up and give it a try. What voltage battery do you use? The input stage in my phono has a well filtered supply putting out 11 volts. Can this be used instead of the battery?

George
  Reply With Quote
Old 30th October 2003, 11:53 AM   #4
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
I use 16v but 11v should be fine. Choose a value for Rd which will give you approx half the supply on the drain. Such low level amps with near zero PSRR are extremely sensitive to power supply quality - that's why i use batteries
  Reply With Quote
Old 23rd November 2003, 09:21 PM   #5
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Quote:
Originally posted by analog_sa
Try 2 parallel 2sk170; drain - 1.2k, source - each 33R, whatever loading resistor suits you at the gate, 2.2uF output cap. Plays fine with 300uV carts and with NiMH batteries, tantalum resistors and MIT RTX output caps better to my ears than any transformer i've tried
I am about to put this together. It is very close to the input stage of the Pearl. I have purchased 2SK170 transistors from MCM several times. They are not listed as GR, BL, or V. But looking at the transistors they are the GR and BL classification.
The Pearl uses the BL type and the IDSS runs 2 - 3 ma with 11 volts Drain to Source. Is there an advantage to using the GR at the low current levels?

George
  Reply With Quote
Old 23rd November 2003, 11:33 PM   #6
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Quote:
Originally posted by analog_sa
Try 2 parallel 2sk170; drain - 1.2k, source - each 33R, whatever loading resistor suits you at the gate, 2.2uF output cap. Plays fine with 300uV carts and with NiMH batteries, tantalum resistors and MIT RTX output caps better to my ears than any transformer i've tried
I am about to put this together. It is very close to the input stage of the Pearl. I have purchased 2SK170 transistors from MCM several times. They are not listed as GR, BL, or V. But looking at the transistors they are the GR and BL classification.
The Pearl uses the BL type and the IDSS runs 2 - 3 ma with 11 volts Drain to Source. Is there an advantage to using the GR at the low current levels?

George
  Reply With Quote
Old 24th November 2003, 11:06 PM   #7
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
This is complicated. Normally use the highest current to get the lowest noise. If you HAVE to starve the fets, then the GR parts may work best, but the BL parts are actually better operating at nominally higher currents. Run at high current, if possible.
  Reply With Quote
Old 24th November 2003, 11:24 PM   #8
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Another suggsetion.......

Keep the operating voltage down if noise is important. I would use under 15 volts.

Jocko
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hi-end Phono vacuum tube preamplifier MM audiodesign Vendor's Bazaar 0 5th March 2009 06:31 AM
Forte Model 2 Preamp phono opamp selection Daveis Pass Labs 0 11th January 2009 05:34 PM
Microphonic phono preamplifier Jaime Tubes / Valves 3 5th June 2007 02:52 PM
Phono preamplifier Pasul Analogue Source 4 4th October 2006 11:03 AM


New To Site? Need Help?

All times are GMT. The time now is 10:33 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2