6J5 input swing - 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 29th December 2006, 12:20 AM   #1
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Default 6J5 input swing

What is the best way to have a 6J5 accept a 7Vrms input cleanly whilst retaining a good operating point. I want to avoid an unbypassed Rk as I want a low rp for low noise.
  Reply With Quote
Old 29th December 2006, 01:43 AM   #2
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
LED's? Mu-follower?
  Reply With Quote
Old 29th December 2006, 02:08 AM   #3
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Nope and nope. You can't exceed the bias voltage at peak in order to avoid grid current. The requirement is odd- lndm, care to elaborate?
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 29th December 2006, 08:07 AM   #4
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Sure. I am designing a phono/pre and have a cascode on paper. With EQ it puts out 7Vrms below 1kHz with my MM cart giving occasional peaks of 70mV. I simply want the second stage to endure these peaks and I have had trouble with another amp that couldn't handle that level. The cascode seems to be happy with this level.
  Reply With Quote
Old 29th December 2006, 08:24 AM   #5
diyAudio Member
 
Miles Prower's Avatar
 
Join Date: May 2005
Location: USA
Blog Entries: 6
Default Re: 6J5 input swing

Quote:
Originally posted by lndm
What is the best way to have a 6J5 accept a 7Vrms input cleanly whilst retaining a good operating point. I want to avoid an unbypassed Rk as I want a low rp for low noise.
If you don't want to use an unbypassed Rk, the only way to do what you want is to run at a very high Vpk. Since 7.0Vrms is a bit less than 10Vp, that's what you're looking at: Vgk= -10Vdc. From the plate characteristics, that'll be right around 250Vdc. Depending on how large the passive load is, the DC rail will go a lot higher than that (or use an active load).

Other than that, unbypassed Rk is the only other option.
Attached Images
File Type: png 6j5-chars.png (34.2 KB, 212 views)
__________________
There are no foxes in atheistholes
www.dolphin-hsl.com
  Reply With Quote
Old 29th December 2006, 11:28 AM   #6
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Do you have passive EQ between the stages?
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 29th December 2006, 06:08 PM   #7
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Yes, the 318us which allows 20kHz to be up by 20dB over the input.
  Reply With Quote
Old 29th December 2006, 07:12 PM   #8
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Other way around- that knocks down the level at high frequencies. With passive EQ, it's very doubtful that you need 7V of overload. But let's go through the exercise: what's your cartridge output spec and the first stage gain?
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 29th December 2006, 07:38 PM   #9
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Below 1kHz the gain is 43dB. I am using an Ortofon OMB. I'm not aware of any specs for it, I just loaded the cartridge, played a few records and watched the screen. Most program material seems to be within 5-10mV with regular peaks at 30mV, some up to 50mV with some recordings, and occasionally 70mV.
  Reply With Quote
Old 29th December 2006, 07:49 PM   #10
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
If you don't want a local feedback put a global one on the same cathode, no other way except attenuating input signal, i.e. loosing precious signal power.
__________________
The Devil is not so terrible as his math model is!
  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
Q on voltage swing JoshK Tubes / Valves 4 13th December 2006 07:11 PM
Manger SWING inertial Planars & Exotics 27 20th November 2006 10:34 AM
how much above B+ will voltage swing in OPT? AudioGeek Tubes / Valves 2 15th April 2005 04:17 AM
Not enough voltage swing in P3A amp ?? Stormo Solid State 1 30th June 2003 08:02 AM
How to swing (for those skilled in the art) Circlotron Everything Else 1 4th December 2002 12:51 AM


New To Site? Need Help?

All times are GMT. The time now is 10:31 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