#26 pre amp - Page 312 - 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 2nd April 2013, 04:56 PM   #3111
diyAudio Member
 
Vinylsavor's Avatar
 
Join Date: Feb 2002
Location: Lindau
Hi!

Quote:
Originally Posted by iko View Post
If you build a phono preamp using a D3A in the first stage then I would strongly recommend that you use a discrete shunt regulator.
Why?

My recently finished D3A LCR phono works extremely well without regulation. Stable and very low noise even for usage with MC cartridge without MC step up

Best regards

Thomas
__________________
http://vinylsavor.blogspot.com/
  Reply With Quote
Old 2nd April 2013, 05:22 PM   #3112
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
And I'm sure that your phono is excellent! I have nothing but respect for your designs.

That being said, the regulation itself isn't what I was emphasising. Low noise and low output impedance supply is the real advantage from that particular shunt regulator. Imagine flat output impedance below 1mOhm, past 20kHz. Low noise you can get with chokes in the supply. Low output impedance too, but the chokes must be quite large to achieve that ($$). I never got a chance to compare, but I would not be shy to put a good discrete shunt regulator next to a choke supply for this particular application (phono+high-ish current input tube).
  Reply With Quote
Old 2nd April 2013, 05:35 PM   #3113
diyAudio Member
 
Vinylsavor's Avatar
 
Join Date: Feb 2002
Location: Lindau
Hi!

I did compare and I prefer the passively filtered supply for transformer coupled stages. There the shunt regulator is fully in the signal path and has it's own imprint on the sound you get. Some might like that. I don't.

Just wanted to point out that it is not a necessitiy to use regulation with the D3a as your post implied

best regards

Thomas
__________________
http://vinylsavor.blogspot.com/
  Reply With Quote
Old 2nd April 2013, 05:36 PM   #3114
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
I agree with you that regulation is not necessary and implication that it'd be was not meant.
  Reply With Quote
Old 3rd April 2013, 12:11 PM   #3115
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
PSU very near 26 still no noise
Attached Images
File Type: jpg DSC00307.jpg (510.7 KB, 322 views)
  Reply With Quote
Old 3rd April 2013, 02:22 PM   #3116
diyAudio Member
 
amandarae's Avatar
 
Join Date: Oct 2004
Location: Diamond Bar, CA
Quote:
Originally Posted by merlin el mago View Post
PSU very near 26 still no noise
Nice!
  Reply With Quote
Old 3rd April 2013, 02:32 PM   #3117
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
Aestetic build Merlin, me like
  Reply With Quote
Old 3rd April 2013, 03:43 PM   #3118
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Thanks stajo, the PSU must be only one power transformer in place of two in series.
  Reply With Quote
Old 3rd April 2013, 04:08 PM   #3119
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
I dont know about that but if you invite me Ill come down and listen
  Reply With Quote
Old 3rd April 2013, 04:32 PM   #3120
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Nice looking build Merlin..

About 12yrs ago I initially tried the VR150/0D3 in my early 26 based line stage design, but found the noise from the gas tube to be excessive in my application.. The plate to line transformers in question were UTC HA-133: 5:1 15K:600 which I am still using. The power amps had modest gain of about 10dB but were driving a rather efficient JBL speaker system (>100dB) wondering now whether I just had a batch of particularly noisy gas tubes.. (NOS) My opinion at the time was that it was almost quiet enough and had the speakers been about 6dB less efficient all would have been well.

My current speaker system is also over the 100dB mark so all of my electronics have to be extremely quiet.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  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



New To Site? Need Help?

All times are GMT. The time now is 07:05 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