Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

VFD vs traditional vacuum tube
VFD vs traditional vacuum tube
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 26th October 2017, 07:45 PM   #31
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by DF96 View Post
A swing from +8.7V to -6.3V is 8% distortion.
Thanks DF
Care to post/link how´s that calculated? , I forgot and my Time Machine is out of fuel
__________________
Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
  Reply With Quote
Old 26th October 2017, 08:55 PM   #32
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Quote:
Originally Posted by ubza1234 View Post
.....under sized power supply and output transformers?.....
A large number of classic guitar amps offer considerable (and adjustable) distortion in preamp stages between a Gain and a Master knob. You can moosh the end of the preamp yet play the power section so soft it is nearly clean.

This is not the same as flogging a pair of 6V6 into a cheap OT. But for many players it is musically useful.

Nelson Pass in the other section posted a plot showing up to ~~10% at clipping. This can be tweaked with bias and loading. A conventional general purpose amplifier triode shows 5%--- so this shows what a "bad" tube the NuTube is. It really is optimized for good glow at low-low current and on/off operation, not linearity.

Process (and ruler) for estimating 2nd Harmonic from loadline asymmetry is in RDH (3rd or 4th).
  Reply With Quote
Old 27th October 2017, 03:58 AM   #33
ubza1234 is offline ubza1234  Australia
diyAudio Member
 
Join Date: Aug 2013
Location: Melbourne
Wow! Thanks for all that!

Merlinb, I read that too cute costs on early guitar amps, they would typically use vastly underrated transformers. The power transformer would sag it's voltage allot adding a kind of compression to it. The power supply just couldn't cut it at full tilt.

Also, main output transformers where typically fairly underrated aswell. These would reach magnetic saturation and add a weird compression effect that would dynamically compress the bass and treble ends more so than the mid range.

They also mentioned non linear biasing, which would clip one half now than the other.

Finally, they mentioned how the output transformer would filter out allot of the really harsh clipping, especially once the transformers reach magnetic saturation.

I read this over on peavey's tech note section, which to be fair is largely marketing, but interesting none the less. Maybe they are exaggerating? What are your thoughts?
  Reply With Quote
Old 27th October 2017, 03:59 AM   #34
ubza1234 is offline ubza1234  Australia
diyAudio Member
 
Join Date: Aug 2013
Location: Melbourne
In saying that, I think they where referring to really really early amplifiers that didn't have a distortion setting. That the baskets thought, "who would ever play it that loud anyway? Well get away with it!" lol
  Reply With Quote
Old 27th October 2017, 10:21 AM   #35
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
+8.7V to -6.3V is an average swing of +- 7.5V, with 1.2V of distortion. Assuming this is second (it will be almost entirely second) then this will be 0.6V of second harmonic and 0.6V of DC. At the signal peak you get 0.6V 2nd plus 0.6V DC. At the zero crossing you get 0.6V DC minus 0.6V 2nd. So there is 7.5V signal plus 0.6V 2nd, which is 8%.
  Reply With Quote

Reply


VFD vs traditional vacuum tubeHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
My first ever vacuum tube amplifier :) Lord Raven Tubes / Valves 15 4th August 2015 01:00 PM
6n2 + fu32 vacuum tube tube headphone amplifier jhin Headphone Systems 1 12th November 2013 03:23 AM
exactly HOW does a tube amp work? or a vacuum tube? realflow100 Tubes / Valves 27 25th September 2012 03:17 AM
Vacuum tube horizontal nathanjh13 Construction Tips 3 26th March 2012 09:38 AM
Vacuum tubes, vacuum capacitors and vacuum relays GREENSTONE USA Vendor's Bazaar 0 19th August 2011 03:38 PM


New To Site? Need Help?

All times are GMT. The time now is 11:45 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki