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 15th January 2011, 05:10 PM   #11
diyAudio Member
 
Join Date: Sep 2006
Location: Malta, Europe
Thanks artosalo for your concise but comprehensive explanation. I'm learning things with every project I make (all of them had problems about which I posted here)!!! I will solder a 1nF across the 6K8 NFB resistor as with longer playing the HF is verging on slight distortion. My speakers are very revealing in the HF range (Yams NS-1000).

Best regards.
  Reply With Quote
Old 15th January 2011, 06:42 PM   #12
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
1nF will give you -3dB at 24kHz.
  Reply With Quote
Old 15th January 2011, 07:06 PM   #13
diyAudio Member
 
Join Date: Sep 2006
Location: Malta, Europe
Quote:
1nF will give you -3dB at 24kHz.
Hi DF, that's quite a high frequency? Does that mean I should use a smaller cap (say 560 or 680pF) for the attenuation of a frequency more within the audible range (say in the 15 to 18 kHz range)? How do you calculate the value? Thanks for your time and input.

Best regards to all.
  Reply With Quote
Old 15th January 2011, 07:36 PM   #14
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Formula is f = 1 / (2 pi C R) so to get a lower cutoff you need a bigger cap.

It might be better to find why you are getting HF distortion. Many modern speakers have a HF lift, so does some modern music. I'm not sure why - maybe intended to impress people rather than sound good.
  Reply With Quote
Old 15th January 2011, 08:06 PM   #15
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
Quote:
1nF will give you -3dB at 24kHz.
True. This has no effection in the audible frequency range in normal case.
My assumption was that the problem is caused by NFB-loop and there may exist ringing at the transients, which in turn could do something to higer discants.
1nF accross the NFB-resistor could decrease this effect.
  Reply With Quote
Old 17th April 2012, 04:08 PM   #16
diyAudio Member
 
Join Date: Sep 2006
Location: Malta, Europe
Default Trioding EF86 in JC Morrison's 6L6GC SE amp

Has anyone trioded the EF86 in this amplifier? In the original circuit the amp is quite sensitive and I wouldn't mind some attenuation to complement my preamp's output. I know I can bypass the preamp but I am quite happy with it.

Not being technical can someone please outline the specific procedure for triode operation - circuit diagram in post# 1.

What component changes need to be made? Is the negative feedback affected by such a change? If yes, how to go about it? The remaining sections I would suppose will remain the same, no?

Thanks for your patience with a complete layman in electronics.
Best regards.
  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
How loud is 250uV white noise? 81bas Solid State 5 9th April 2010 05:43 PM
Carver M-1.5t loud noise on one channel hybridge Solid State 1 25th March 2010 12:09 AM
buzz noise from loud speakers vibeline Multi-Way 9 7th January 2007 06:19 PM
Carver M1.0t Loud "tong tong" noise Visigoth Solid State 9 4th January 2006 12:17 AM
Reduce NFB but keep noise/hum down? K-amps Solid State 12 17th March 2005 09:47 PM


New To Site? Need Help?

All times are GMT. The time now is 09:49 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