Diy Phono stage - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 28th November 2003, 02:18 AM   #11
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
Without the noise concellation circuit, the PS noise may already be considerably below the signal level, depending on the nature of the PS. Let's say it's 60db below for example.
Wouldn't you say this is fascinating enough to merit a thread of its'own?

Mind you, I do have great interest in this, anything low signal level is a bit like RF, it does have a story to tell...and the smallest of small signals matters.

It also shows you what could go on at higher signal levels...totally capturing if you'd ask me...

Like mainframes in computors, there's a lot of info and tips to be found in the pro world.

Cheers,
__________________
Frank
  Reply With Quote
Old 28th November 2003, 03:44 AM   #12
diyAudio Member
 
Join Date: Sep 2003
Location: Texas
Would make a very interesting thread! If we could get Mr. Broskie to join the forum, he could run that thread with one hand tied behind his back.

As a poor to average tube circuit designer, unfortunately, the best I can do is to refer everyone to TCJ where John gives many examples of noise cancellation tricks.

In this particular phono preamp, the output stage is a common cathode diff amp. The second grid is normally grounded, but in this case Broskie feeds the PS noise into the second grid and this noise, in phase with the PS noise introduced normally into the rest of the circuit, cancels the normal PS noise (similar to the way NFB would be employed in this topology). This design is very clever (at least to me) and with the right values of capacitors should have an extremely low noise floor.

Or did you have something else in mind Frank?
  Reply With Quote
Old 28th November 2003, 11:13 PM   #13
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
This design is very clever (at least to me) and with the right values of capacitors should have an extremely low noise floor.
It would indeed.

Better still would be to apply the same technique of noise cancellation in the PS in the first place.
Which is excactly what you do by using series regs.

That, in a nutshell, is my major quibble with TCJ; if your not savvy or an engineer you're just left second guessing.

Now, combining both appropriately could yield very high noise reduction indeed and hopefully a very good sounding phono preamp.

BTW, it's worthwhile to go through the pages following the original article.

FWIW, noise cancellation techniques are not new at all and can be found in Pro equipment from the Fifties or maybe even prior to that period.

Thanks to J.B. we now have most of it in one convenient place on the web.

Quote:
Or did you have something else in mind Frank?
No, not really...I had my 2 cents added. TA.

Cheers,

P.S. You're much better than you give yourself credit for IMO.
__________________
Frank
  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
NS-10 phono stage ponger Pass Labs 9 28th March 2011 08:57 AM
DIY phono to replace roksan phono stage seroxatmad Analog Line Level 6 14th December 2008 05:46 PM
new phono stage or old preamp with phono? flohmann Analog Line Level 2 2nd October 2008 09:51 PM
Should I replace Scott 222C phono stage with Claret phono stage? Bing Yang Analogue Source 0 22nd August 2005 06:41 AM
Phono Stage ruangrit Analogue Source 1 11th October 2003 10:13 AM


New To Site? Need Help?

All times are GMT. The time now is 04:29 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