OTL Asylum

OTL, Output Transformerless Amplifier User Group.

Return to OTL Asylum

Message Sort: Post Order or Asylum Reverse Threaded

parallelling 6AS7s

83.109.164.66
Posted on October 30, 2004 at 05:10:57
Ropert


 
I have built four OTLs with 6AS7s, one with two tubes, one with six, and two with eight.
I have been confronted by many 'experts' regarding the tube's poor match and the problems that are sure to arrise. I have had the first amp for over a year, and no problems at all so far.
So the question is: Are these tube really as hopeless in regards to paralleling as the experts claim and have I just been lucky till now?
I do not know the credibility of these 'experts', but there are more than one, and they argue as if they really know what they are talking about.
Any comments?
If cathode resistors for current sharing is necessary, what value should they be?

 

Hide full thread outline!
    ...
Re: parallelling 6AS7s, posted on November 1, 2004 at 07:40:44
Lew
Audiophile

Posts: 10911
Location: Bethesda, Maryland
Joined: December 11, 2000
 Of course it's not "hopeless" to parallel 6AS7s. That is the basis of Atma-sphere amplifier design, and I would challenge any "expert" to show that Atma-sphere amps in the field have been anything but reliable. You do have to be careful about what brand and type of 6AS7 you choose, and it is best if you can "match" tubes as closely as possible. Atma-sphere has been installing 1-ohm resistors on the plates or cathodes (don't know which) of 6AS7s for a few years now, in order to promote current-sharing between and among tubes that are paralleled. I cannot comment on the effect of this mod, since my own amps do not use 6AS7s, etc.

 

Page processed in 0.017 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]