Low Distortion High Dynamic Range Pre-amp - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 5th December 2006, 12:17 AM   #1
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Default Low Distortion High Dynamic Range Pre-amp

Is anyone interested in an excellent quality very low distortion complementary symerty class A pre-amp running at amplifier voltages offering high dynamic range while remaining very simple.

It is seldom that one finds a pre-amp that can run off the same high voltage supply of your amplifier and I may have just the thing.

Kind regards

Nico
  Reply With Quote
Old 5th December 2006, 12:27 AM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default Re: Low Distortion High Dynamic Range Pre-amp

Quote:
Originally posted by Nico Ras
Is anyone interested in an excellent quality very low distortion complementary symerty class A pre-amp running at amplifier voltages offering high dynamic range while remaining very simple.

It is seldom that one finds a pre-amp that can run off the same high voltage supply of your amplifier and I may have just the thing.

Kind regards

Nico

hehe

just shoot.....
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 5th December 2006, 08:54 AM   #3
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
I have never published any of my designs on diyAudio forum but will gladly do this if there are some interest shown by other enthusiasts and could turn it into a small project.

My second calling is that of being an acoustic jazz musician for more than 30 years, playing several instruments, thus the enjoyment of music to me is very much determined by the accuracy that an instrument's or voice character is retained when reproduced by the sound equipment that I design and use.

Although the measurements are excellent (for instance, our Hewlett Packard distortion analyser cannot measure the distortion with a 2V input signal (typical of a CD player)at any frequency up to 100kHz. Enjoying what you hear and being able to relate to the music is the real test.

It is my experience that it is not possible to design the ultimate equipment that will please every individual, simply because the vast majority of people has never actually heard the real instrument playing and therefor has no point of reference, thus it is perseption that set a trend not reality.

What I believe is one should strive for is to design simplistic audio circuits that approaches that of the ampliwire add ing as little character of its own.

Kindest regards

Nico
Attached Images
File Type: jpg ras rev03 circuit.jpg (57.1 KB, 2688 views)
  Reply With Quote
Old 5th December 2006, 09:03 AM   #4
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally posted by Nico Ras
I have never published any of my designs on diyAudio forum but will gladly do this if there are some interest shown by other enthusiasts and could turn it into a small project.

My second calling is that of being an acoustic jazz musician for more than 30 years, playing several instruments, thus the enjoyment of music to me is very much determined by the accuracy that an instrument's or voice character is retained when reproduced by the sound equipment that I design and use.

Although the measurements are excellent (for instance, our Hewlett Packard distortion analyser cannot measure the distortion with a 2V input signal (typical of a CD player)at any frequency up to 100kHz. Enjoying what you hear and being able to relate to the music is the real test.

It is my experience that it is not possible to design the ultimate equipment that will please every individual, simply because the vast majority of people has never actually heard the real instrument playing and therefor has no point of reference, thus it is perseption that set a trend not reality.

What I believe is one should strive for is to design simplistic audio circuits that approaches that of the ampliwire add ing as little character of its own.

Kindest regards

Nico

Hi Nico,

Nice design. I have a question on your output transistors. You show the BD139/140 series, which IIRC have a max Vce of 80V? That may be problematic with 100V total supply. But maybe this is just for sim purposes, maybe you used other transistors in real world?

Jan Didden
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 5th December 2006, 09:44 AM   #5
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
I have been using this design for the past three years, (always busy tweaking something or other) with 30V stabilised supply (LM317/337) followed by a capacitance multiplier.

The BD139/BD140 combination sounds nicer than some other transistors I have used. if one can define nicer.

But you are absolutely right, the transistors of choice for a 50V supply would probably be MJE15034/5, which I have used in the past.

If you asked me how they sounded, then I must admit, probably different whether different is better or worse is really difficult to say.

The reason for the power transistors are that of reduced thermal noise.
  Reply With Quote
Old 5th December 2006, 09:50 AM   #6
steenoe is offline steenoe  Denmark
diyAudio Member
 
steenoe's Avatar
 
Join Date: Mar 2004
Quote:
What I believe is one should strive for is to design simplistic audio circuits that approaches that of the ampliwire add ing as little character of its own.
Nice line, Nico
If all audiogear was made with that idea in mind.......
Thanks for sharing the schematic.

Steen
  Reply With Quote
Old 5th December 2006, 10:32 AM   #7
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Hi Steen,

You may not be surprised at all, but most people purchasing commercial equipment has no idea what it should sound like. That is why it is called commercial equipment. On the other hand, most youngsters these days listen to music generated electronically, what exactly should it sound like, who knows. There is no point of reference at all.

If all sound equipment was designed that way, it won't sell because it will not vibrate the windows and doors and the owner cannot impress his buddies with the fact that everything rattles when he cranks up the volume.

One of the easiest ways to create sloppy single note bass that sounds like a wet F&%T is to skimp on the power supply. It is almost always 100Hz.
  Reply With Quote
Old 5th December 2006, 10:49 AM   #8
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Me again Steen, I get carried away when at times, us fanatics try to design stuff that could have sounded pretty reasonable if it did not pass through 100s of op-amps, kms of cable, spit covered microphones, overdriven PeeVee amps, and a hung over recording engineers that compresses the audio to the point that all frequencies are at the same loudness.

Now what, who are we trying to please!

We actually design audio equipment essentially for our own pleasure, never to impress anybody other than ourselves.

But if someone else shares the same enthusiasm, it genreates even more enthusiasm, friendships are created and great ideas and experiences are shared.

It all becomes worth while if you can tell that the artist is playing on a Gibson, Fender or Hoffnar. But in most cases the average listener would not know if it is a bass drum, guitar or the bottom notes on a piano.
  Reply With Quote
Old 5th December 2006, 07:19 PM   #9
flg is offline flg  United States
diyAudio Member
 
flg's Avatar
 
Join Date: Jul 2005
Location: North East
I like it. I'll take a look on the sim later... What other transistors have you tryed What type of output impeadance are you driving
  Reply With Quote
Old 5th December 2006, 07:51 PM   #10
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
I am driving into my main amp, input is about 22K. My prvious design used 10 x small signal transistors in parralel in each of the differential input stages. The geometric sum of the non coherent noise causes a 2.5dB noise reduction. This was great in the days of Linn, Itok, Karma, etc, etc.

I found that power transistors achieves almost the same result, having larger junctions.

To be absolutely honest, I built the original using BD139/140 some three years ago (and still use it every day) I used MJE15035/6, for a fellow enthusiast, since I had several hand matched pairs left from the time I designed my main amp.

I remember when we first compared the two pre-amps, they sounded different, but again it may all be in the mind. We discussed and philosified about it but never concluded anything, neither sounded better than the other. Nor could we really say it was really different.

It could have been because the two pre-amps were running of different rails. The BDs where running at 38V while the MJEs were at 50V. Again, which one sounded better, heck I don't know they both sounded damn good!

If you ask is it the best I have ever heard. Of course I designed it, have you ever met anyone who's own brewed system is not the best?



Kindest Regards
  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
Dynamic Range...? Lyra Digital Source 40 2nd October 2007 11:44 PM
SNR/Dynamic range worsens in low frequency range. percy Digital Source 3 1st June 2006 12:41 PM
The dynamic range of 16 bits Christer Digital Source 246 23rd June 2003 09:59 PM


New To Site? Need Help?

All times are GMT. The time now is 04:36 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