el84pse schem, need advice - 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 11th May 2011, 08:45 AM   #1
diyAudio Member
 
Join Date: Aug 2009
Smile el84pse schem, need advice

hello......
i want to build an amp with the part that i have....
here the schem....
i need your advice or criticsm...
or maybe, there's better schem ...

nb : is it possible to make 6sn7 driver stage to drive el84 pse....

thanks
Attached Images
File Type: png el84pse2.png (118.3 KB, 279 views)
  Reply With Quote
Old 11th May 2011, 10:29 AM   #2
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
What is the triode valve - the circuit does not say? The data on the circuit suggests that it is a low impedance triode: mu~30, gm~10mA/V.

The first stage uses an active load, which will reduce distortion there, yet most distortion will actually come from the output stage.
  Reply With Quote
Old 11th May 2011, 02:33 PM   #3
diyAudio Member
 
the_manta's Avatar
 
Join Date: Nov 2006
Location: Munich, Bavaria
6SN7, yes, but in term sof optics a desaster

6SN7 as single triode or SRPP has very low . But you need for feedback to get a good damping factor. So a 2-staged topology is the way to go.
  Reply With Quote
Old 11th May 2011, 02:38 PM   #4
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
It doesn't have any feedback. Maybe it should.
  Reply With Quote
Old 11th May 2011, 03:21 PM   #5
diyAudio Member
 
Join Date: Aug 2009
hello
thanks for the input everybody...
the driver use 6922/6dj8

should i use global feedback or local feedback..?
  Reply With Quote
Old 11th May 2011, 03:45 PM   #6
diyAudio Member
 
Join Date: Aug 2009
Quote:
Originally Posted by the_manta View Post
6SN7, yes, but in term sof optics a desaster

6SN7 as single triode or SRPP has very low . But you need for feedback to get a good damping factor. So a 2-staged topology is the way to go.
hello
how much B+ that 6sn7 needed to operate at optimum linearity...

is it 300v enough for 6sn7?

sorry for the bad english

thanks
  Reply With Quote
Old 11th May 2011, 04:24 PM   #7
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
The 6DJ8 should give you a low distortion first stage. 6SN7 would definitely have less gain, and might have slightly higher distortion.

You don't have enough spare gain for enough NFB, so no NFB is better than insufficient NFB. I assume you prefer single-ended pentode outputs? I would use the two EL84 as P-P, but each to their own!
  Reply With Quote
Old 11th May 2011, 05:35 PM   #8
diyAudio Member
 
the_manta's Avatar
 
Join Date: Nov 2006
Location: Munich, Bavaria
Sorry sorry sorry....I thought you wanted to use the EL84 as Pentode Now I see it's triode conected. Well then you don't basically need feedback, but I always recommend at least a bit.

Whether you want to use local feedback (I mean like that) or global is up to you. With gobal feedback it's more difficult to get a stable amplifier because of the phase shift of the output transformer and all the coupling caps. (Ideal feedback doesn't have any phase shifting components in its way, look at typical Transistor amp schematics, they are more or less completely DC coupled)

to the driver: A 6SN7 needs a bit more supply voltage and current to sound good, but 300V is adequate. 6DJ8/ECC88 is a very good driver and matches the EL84 shape :-) ECC88 doesn't need much volatge but at least 7 to 8mA. This gives nice working points.

Withe the 6DJ8/ECC88 and little or no feedback you have plety of possibilities to design your driver. One tube for both channels would be the simple way. with two systems, there are many many more...grounded cathode followed by cathode follwer, -follwer, SRPP, Diff-amp, cascode etc.....

Just try a few and keep the one you like :-)
  Reply With Quote
Old 11th May 2011, 07:30 PM   #9
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Sorry, I had not spotted the EL84 triode connection. As long as you don't drive it too hard it may be fine without feedback. Given a simple output stage, it seems sensible to have a simple input stage too.
  Reply With Quote
Old 13th May 2011, 09:00 AM   #10
diyAudio Member
 
Join Date: Aug 2009
thanks again for great input....
i'm thinking about PushPull output, but i have to buy PP Trans..
is it worth to change to Pushpull compared to PSE...(el84) ?
the loudspeaker is fullrange at 90db sens...
  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 to understand this schem please! apr Instruments and Amps 11 1st January 2009 08:06 PM
Hammond 9500 schem. mashaffer Instruments and Amps 0 5th November 2007 11:23 PM
Tip33.....anyone got a schem. diesel_tech Solid State 9 23rd March 2007 11:55 PM
Need Schem Protech SPA450 ! derguteton Solid State 0 14th April 2005 09:07 AM
help, schem for sherwood psychosteve Solid State 0 10th November 2004 05:35 PM


New To Site? Need Help?

All times are GMT. The time now is 11:19 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