|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
96.234.41.97
In Reply to: RE: "While not perfect, it is still better then anything else available" seems you forgot to add IMHO...nt posted by Garg0yle on September 19, 2015 at 09:44:20
You are correct about the tube but not the circuit. And some triodes are more linear than others. The fabled 300B is just very good. The 2A3 is more linear and I'm told the 45 more linear yet. The problem is power.
However a screen drive 509 or 519 is a very linear triode and a push/pull pair is capable of well over 200 watts. And on another front the old Sony VFETs are a very linear solid state triode and they don't need an output transformer. Their curves look like a 2A3 and you can get power out of them too.
Follow Ups:
As I mentioned in my post to start this thread...the problem may not be so much the device...although even the VFets and screen driven 509s are not as linear as a good DHT, but using it in push pull. So, Nelson's SIT amp might be the answer but even that, I am told, doesn't converge with DHTs. It is also power limited.
I got pretty close with my NAT Symbiosis, which was a Class A SE(T) hybrid. Input and driver were tubes and the output was a single big industrial MOSFET mounted on the bottom of a vertically mounted monster heatsink. It delivered a true 100 watts of Class A power with no negative feedback and had the tone of a nearly perfect SET and SS like bass control and drive. HOWEVER, it was still missing something that was difficult to pin down and in the end I preferred true SET amps over it. I wish I could find some measurement data on it but there seems to be none because it was probably close to ideal but missing in a key area.
In terms of imaging it was more like great SS than holographic 3d.
According to a friend who loved and used the 2A3 the Sony VFET curves looked about as good as a 2A3. And from a friend who made commercial amps a screen drive 519 did not just show decent triode curve but very good ones.
By the way one of my big questions in audio and you do it too is class A SET. What is a non class A audio amp? SET has to be class A in a classic analog amp. There's no other real option.
The problem with VFETs and SITs are what's available power wise. There's not enough call from audio for VFETs. I think big ones were used in TV power supplies in the 70s. Audio alone can't support manufacture. But if it could we'd have high power triode performance without transformers.
On your hybrid you didn't have triode output so I'm not surprised you didn't quite like the sound. A MOSFET isn't a triode device while a VFET is a solid state triode.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: