Best low-noise low-distortion buffer? - 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 8th December 2003, 09:03 AM   #1
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
Default Best low-noise low-distortion buffer?

At the output of a CD player project I need to buffer (and possibly multiply by two) the output of a passive filter. There's plenty of power supply voltage (+-18V).

The buffer should be fit for driving both phono and XLR inputs of preamps.

I don't care too much if the buffer introduces an offset voltage as long as it doesn't change too much with temperature and across channels.

I have been thinking about opamps as unity-gain buffers and maybe in a gain of +2. Now I wonder if I can get better audio performance with a source follower. I have been reading Douglas Self's page on CPF source followers (http://www.dself.dsl.pipex.com/ampins/discrete/cfp.htm).

What I want to ask you is if this is my best option. Or will a good opamp like for instance the OPA2134 offer better sound quality?


Greetings,
BÝrge
  Reply With Quote
Old 8th December 2003, 08:51 PM   #2
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: USA
The better chip-op-amps are very good. I don't see how the CPF is any better. It is more work, has substantial offset, can't give gain as shown, and is very prone to self-oscillation (which can be a royal pain to find and fix).
  Reply With Quote
Old 9th December 2003, 02:41 AM   #3
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
I do not like op-amps as unity gain buffers. JFET followers sound good, although they will not drive 600 ohms.

CFP are ok, but I have never needed one as a buffer for a CDP. They may sound a bit too constricted, when compared to a follower.

Diamond buffers would work fine, if you need current drive.


If your D/A chip is a R-2R type, just change the load resistor to get that 6 dB gain.

Jocko
  Reply With Quote
Old 9th December 2003, 08:51 AM   #4
PAM is offline PAM  Netherlands
diyAudio Member
 
PAM's Avatar
 
Join Date: May 2002
Default easy buffer

An easy way to make a good buffer is the BUF 634.
WADIA used them in there CD players.
I compared a Musical Fidality X10D (tubes) with an stand alone batterie powered BUF 634. The BUF 634 wins clearly at 1/10 th of the costs.
The BUF 634 is cheap, fast and powerfull.
  Reply With Quote
Old 9th December 2003, 09:01 AM   #5
sobazz is offline sobazz  Denmark
diyAudio Member
 
sobazz's Avatar
 
Join Date: Apr 2003
Location: Jutland
In the high-end headphone amp project PPA they chose Intersils HA3-5002 over BUF634.... And Intersils is cheaper.
  Reply With Quote
Old 9th December 2003, 09:17 AM   #6
diyAudio Member
 
Join Date: Jan 2002
Location: Italy
Default Need good buffer schematic

I wonder if anybody can help me out with a buffer circuit design.

I'm currently building an APOX preamp and I would like to have a couple of tape outputs. Just tapping into the input selection bus doesn't seem to me a good idea, bacause I'd probably end up overloading the source.

Can anybody point me to a very good buffer schematic? Possibly I'd like a tested design, so that I don't have to experiment too much...
It seems to me that it should have a 1:1 gain. FYI, the signal bus is balanced.
  Reply With Quote
Old 9th December 2003, 09:19 AM   #7
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
Thans folks

Jocko, what is a diamond buffer?

My dac is a current output type which I planned to filter passively and then buffer.

I saw a previous thread on the use of CPF followers(Help a nOOb out with an emitter-follower...) which seemed very interesting. Do you think this circuit with a constant current generator is capable of pulling 600Ohms?

Another issue is that the signal current those 600Ohms will be downscaled by beta and be seen at the base. However, I don't mind (small) constant base currents.

So the question remains: Do you have any experience with FET CPFs?

What I plan to do is to make a test board with an opamp socket and a couple followers that I can jump in and out. Now I'm just trying to figure out which followers are worthy of occupying FR4 real estate

--
BÝrge
  Reply With Quote
Old 9th December 2003, 12:40 PM   #8
diyAudio Member
 
johnferrier's Avatar
 
Join Date: Sep 2003
Location: WA
Default Re: Need good buffer schematic

Quote:
Originally posted by m.parigi
Can anybody point me to a very good buffer schematic? Possibly I'd like a tested design, so that I don't have to experiment too much...

http://www.elecdesign.com/Globals/Pl...tent/2800.html


JF
  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
buffer noise Sheldon Chip Amps 24 27th July 2010 01:10 AM
Lowering Buffer Opamp Distortion mrfeedback Solid State 9 8th January 2009 04:16 PM
Simple Low Distortion JFET Buffer wrenchone Solid State 21 29th January 2007 08:16 PM
testing distortion/noise on a X'd amp? rif Pass Labs 1 18th August 2004 06:23 PM


New To Site? Need Help?

All times are GMT. The time now is 12:19 PM.


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