6V6 line preamp - Page 112 - 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 12th September 2012, 05:56 AM   #1111
harlee is offline harlee  Singapore
diyAudio Member
 
Join Date: Nov 2006
Ok, found it, the gain is 7, no wonder it's has the same feel as my(once upon a time) 01A preamp.

Salas or anyone,
have tried cascade DN2540 CCS on the plate? And Schottky diode at the cathode?
  Reply With Quote
Old 13th September 2012, 03:36 AM   #1112
harlee is offline harlee  Singapore
diyAudio Member
 
Join Date: Nov 2006
I found 2pcs of caddock 100R, swop in to replace the 1K grid resistors...WOW...
Urge you guys to try!
  Reply With Quote
Old 13th September 2012, 09:15 AM   #1113
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Not a huge proponent of expensive tweaks, but this is a simple enough layout, that individual componenets can have significant effect on final sound, IMO.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 13th September 2012, 02:50 PM   #1114
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by harlee View Post
This is a wonderful line amp, have been listening to it for the past week.
But it seems to have a bit too low a gain, I crank it all the way up and it's still bearable. Was the gain at 15? Must have lost it some where?
The gain was measured as 15dB with 5K load and informed here. 15dB or ~5.5 times and you get 7 times because you ended up with more load due to less B+. So all is normal.
  Reply With Quote
Old 13th September 2012, 02:55 PM   #1115
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by harlee View Post
Ok, found it, the gain is 7, no wonder it's has the same feel as my(once upon a time) 01A preamp.

Salas or anyone,
have tried cascade DN2540 CCS on the plate? And Schottky diode at the cathode?
I had tried other Mosfets, enhancement mode ones in cascode, the gain went up to 10 times or something don't remember exactly it was long ago. But I remember I did not like it better and I put the resistor back. Your mileage may vary.
  Reply With Quote
Old 13th September 2012, 03:12 PM   #1116
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
P.S. Your ATC50's are low sens. of course, but what is the level of your source and the input that the Aragon amps require for full power? 17dB line gain (7) you got is not considered that low these days.
  Reply With Quote
Old 12th October 2012, 11:28 AM   #1117
diyAudio Member
 
Join Date: Apr 2009
Hi all, Yassas Salas,

I have a paire of OPT (5:2) that would be good for preamp and was looking for tube that could feat them.
I found the 6V6 interesting and had a look on GG with "6V6 pre amp" wording and found this 112 pages thread that is runnning since 2007. Wow.

So, as I do not plan to read all this pages, sorry for that, what is the latest schematic of this pre amp?
Do you think that my transfo with 5:2 (2,5Kohm/400ohm) would be good for the 6V6?

Thanks,
Vincent
  Reply With Quote
Old 12th October 2012, 11:48 AM   #1118
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
You would need a primary around the 8K mark to load a 6V6 well for THD, certainly no less than 5K. The schematics are linked from post#1 either for normal gaining preamp or impedance buffer type. The only further comment is 7.5K load resistor and 300V can be used if the 330-340V aren't handy. Voltage gain is 15dB with 5K resistive load or 17dB with 7.5K.
  Reply With Quote
Old 12th October 2012, 03:53 PM   #1119
diyAudio Member
 
Join Date: Apr 2009
Hi Salas,
thanks for the fat answer and sorry, Ive been to fast and did not saw the link on the first page. shame on me.
I was thinking to have a 800ohm resistor on the output to fix the working resistance to 5Kohm on the tube side. That would feet with your advice.
the only doubt I have is about the impedance of 800ohm on preamp output.

How to know if it will be good calculated for my amp?

Vincent

Vincent
  Reply With Quote
Old 12th October 2012, 05:28 PM   #1120
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
As it is with 5K resistive load it has 1650 Ohm output impedance in gain mode or 250 Ohm in buffer mode, still its vigorous subjectively.
It runs 20mA+ bias current though, not a common line pre config for tubes and bias choices.
So your 800 Ohm halves that gain version's Zo figure already. Check point should be where you go for voltage gain at secondary and OPT ratio.
  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
Help me design my DAC/Line Preamp. kuroguy Tubes / Valves 7 2nd April 2009 09:31 PM
preamp line ctt richwalters Tubes / Valves 1 7th March 2008 05:34 PM
Preamp for Line In and Mic blur Instruments and Amps 1 4th January 2007 05:02 PM
Line stage preamp, based on SY's "Heretical Unity gain line stage" Danko Tubes / Valves 23 18th July 2005 05:07 AM
Line preamp for 2A3 amp Petman Tubes / Valves 0 24th May 2002 04:11 PM


New To Site? Need Help?

All times are GMT. The time now is 05:15 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