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In Reply to: Parallel SE 6V6 posted by FM on May 15, 2001 at 09:28:44:
I am no expert here but have to agree with Gordon. Why triode wire a pentode? You can buy all sorts of real triodes. I could understand if triodes were unavailable but they are available.
What happens to a pentode when it is triode strapped, don't parameters change?
Why reinvent the wheel???
Follow Ups:
Read my IDT triodes page for a good explanation and plate family of curves: http://www.sasaudiolabs.com/tubes1a.htm
The curves are just like any other triode. The plate resistance of a 6550 or KT88 is nearly identical to a 300B. The distortion is lower. The DHT of the 30s just don't measure up and the directly heated cathode is a pain in the butt, besides the hum problems that Stereophile mentioned. I sure wouldn't want to spend my hard earned money on hum all over the room.
> > The curves are just like any other triode. The plate resistance of a 6550 or KT88 is nearly identical to a 300B. The distortion is lower. < <The web page you mention does not back up this claim of lower distortion. Where is the proof?
I have no problem with you or your products, Steve. They appear to be quality products at a very reasonable price. I take issue with your unsubstantiated claim that a triode connected KT88 has lower distortion than a 300B.
During our last debate on this matter, I looked into the issue by doing a graphical analysis (Crowhurst's method) of several operating points. In all cases, the 300B had much lower 2nd and 3rd harmonic distortion than a triode connected KT88 at the same operating point. One operating point is all it would take to prove your point, but you were not forthcoming with one.
Perhaps if you followed through with real proof of this claim (instead of hand waving and chest pounding) or stopped making this claim, you'd elicit more positive responses to your posts on this forum.
Not trying to reinvent the wheel but the 6V6 is one of the best sounding tubes out there IMHO,thats why I recommended it.Its pretty linear and offers low rP when triode wired and above of all,they sound spectacular.They are also cheap and plentiful,usually $40 bucks a quad.To me they deliver a sound comparible to many DHT's if not better.
What actually is the Rp of a triode connected 6V6 ?
1960 ohms at 250v plate
Right on. Look at some schematics of DHT amps and you see 0.1uf coupling caps rolling off the bass and the limited high frequency response. It is time to move on to better.
Yep, time to move on from 300Bs, 2A3s, 45's to triode wired KT-88s.
Why stop there though? I think we need to keep going, to solid state devices for more power and reliability. Yep, right on brother. Why limit your thinking? I have some great web sites proving the technical superiority of solid state amps. Let me dig 'em out and send 'em to you. Wait till you read this stuff! When you compare the KT-88 to Solid State w/feedback, well, 'chit man, it's all over!!! I can't wait till you see the technical proof explained on these web sites. You'll cream, my man. And the power - Gawd, the power!Oh, yeah, if you do have any of those crappy old hum ridden DHT tubes left over after testing, can you send them to me instead of ditching'em? my uncle builds frames and has this really old welding thing-a-ma-jig that uses them, takes 300Bs I think, (but I think he can use 45 and 2A3 too) so they would be put to good use. Sure beats using them in amps, right?
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