#26 pre amp - Page 110 - 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 3rd July 2011, 06:13 PM   #1091
diyAudio Member
 
Vinylsavor's Avatar
 
Join Date: Feb 2002
Location: Lindau
Hi!

Ok, so that could have been the cause of the noise. Once that is cleared out, you can optimize the preamp.

I have suggested many times already the Lundahl LL1660 in 4.5:1 for a 26 preamp. That's what I use, followed by a Dave Slage autoformer volume control.

You could go a step by step approach, first replace the plate choke by the step down. If you like it, proceed with the TVC. The TVC will bring the biggest sound improvement in my experience. However gain will be less. With the step down you get approx 3dB of gain from the 26.

I prefer cathode bias with ultrapath cap on my linestage, I'm not so fond of battery bias. With a 26 you could also easily try filament bias.

Once you tried this and like it you could also try a passive LCL supply for the filaments to see which you like better.

You can get the suitable Lundahl transformers and chokes from me. I also have suitable high quality power transformers for B+ and filaments.

vgeorge who posted in this thread also switched from plate choke to 1660 4.5:1 step down and liked it a lot.

Best regards

Thomas
__________________
http://vinylsavor.blogspot.com/
  Reply With Quote
Old 3rd July 2011, 06:51 PM   #1092
diyAudio Member
 
Join Date: Sep 2003
Location: London
For all of you using transistor amps, Thomas is your man and his system of LL1660 and TVC seems a bit of a no-brainer.

My preference for small teflon output caps is only because I have a tube input stage on my amp and short leads - in fact the plan is to put the 26 stage in the amp chassis. I go for extremely simple solutions!

Andy
  Reply With Quote
Old 4th July 2011, 10:43 AM   #1093
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
So if I use LL1660 & TVC can I avoid the output cap?
  Reply With Quote
Old 4th July 2011, 11:17 AM   #1094
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Thomas, can I use other output Tx to use my Senns HD600 & my 100K input impedance SS power amps?
  Reply With Quote
Old 4th July 2011, 01:15 PM   #1095
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Quote:
Originally Posted by merlin el mago View Post
So if I use LL1660 & TVC can I avoid the output cap?
Yes, even without the TVC.
  Reply With Quote
Old 4th July 2011, 01:19 PM   #1096
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Thank you George
  Reply With Quote
Old 4th July 2011, 01:47 PM   #1097
diyAudio Member
 
coolzero's Avatar
 
Join Date: Sep 2009
Location: UAE
Quote:
Originally Posted by vgeorge View Post
Yes, even without the TVC.

you mean like this?

Click the image to open in full size.
  Reply With Quote
Old 4th July 2011, 01:59 PM   #1098
diyAudio Member
 
coolzero's Avatar
 
Join Date: Sep 2009
Location: UAE
Quote:
Originally Posted by Vinylsavor View Post
Hi!

Ok, so that could have been the cause of the noise. Once that is cleared out, you can optimize the preamp.

I have suggested many times already the Lundahl LL1660 in 4.5:1 for a 26 preamp. That's what I use, followed by a Dave Slage autoformer volume control.

You could go a step by step approach, first replace the plate choke by the step down. If you like it, proceed with the TVC. The TVC will bring the biggest sound improvement in my experience. However gain will be less. With the step down you get approx 3dB of gain from the 26.

I prefer cathode bias with ultrapath cap on my linestage, I'm not so fond of battery bias. With a 26 you could also easily try filament bias.

Once you tried this and like it you could also try a passive LCL supply for the filaments to see which you like better.

You can get the suitable Lundahl transformers and chokes from me. I also have suitable high quality power transformers for B+ and filaments.

vgeorge who posted in this thread also switched from plate choke to 1660 4.5:1 step down and liked it a lot.

Best regards

Thomas
I tried simple cathode bias and filament bias but end up with battery gird bias because I liked the sound. I initially tried passive LCL as well for PSU. But when used SALAS HVPSU, I felt a big improvement over sound and noise level so started using that. However I am still open for little bit of experiment if I could get the best out of 26. Is it possible you to put a relevant schematic for ultrapath/stepdown combination?
  Reply With Quote
Old 4th July 2011, 02:53 PM   #1099
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
[QUOTE=coolzero;2628146]you mean like this?


Yes, it is very close to what I am using now.
  Reply With Quote
Old 4th July 2011, 04:43 PM   #1100
diyAudio Member
 
Vinylsavor's Avatar
 
Join Date: Feb 2002
Location: Lindau
Hi!

Quote:
Originally Posted by merlin el mago View Post
Thomas, can I use other output Tx to use my Senns HD600 & my 100K input impedance SS power amps?
I think we discussed that already. I don't remember the impedance needs of your HD600. Don't try to cover to different applications with one premap, the compromise might be too big

Thomas
__________________
http://vinylsavor.blogspot.com/
  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 04:06 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