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Mosfet amps A true compromise betw. tubes and SS?

I heard from several people that Mosfet SS amps are a nice compromise between tubes and SS amps.
There is one manufacturer in particular I am interested
http://www.wbe-audio.de,s croll down to Fusion 700 (its a German made amp, but he has an English web page) who calls his hybrid amp a Mono tube mosfet amp.
I would really appreciate if someone who has more insight would tell me a bit more of advantages and shortcomings of this design and if the claim: "sound of tubes with power of SS" is true or not. Also I would like to know if these are fast amps, as I plan to maybe use them with my ML Prodigy, should the Wolcott amps, I bought recently, not work satisfactorily.
tekunda
gpdavis1
40 posts
 
Muralman1 - what is a "step-up capacitor"?

BAT also has a very neutral sound MOSFET amp in their VK-200 (now replaced by the VK-250). Two gain stages and no global feedback. A very "Passish" design philosophy. If one is looking for some inexpensive but well built MOSFET amps they might want to try the last of Sony's ES amps. Especially the TAN90ES. Not a BAT or Pass, but quite inexpensive and at least their equal in quality, if not quite there to the nth degree in sound. Also fairly "Passish" in design philosophy.
muralman1
1,527 posts
 
Nearly all multi stage amps need a capacitor in line to facilitate the bridge between the two. The trouble is, any capacitor or resistor in line with the signal is going to add it's own degradation of the signal.

It isn't easy to create a circuit with no resistors or capacitors in line with the signal. The Pass X and XA series not only do without, any bit of distortion getting through is canceled at the output through Supersymmetry.
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swampwalker
5,132 posts
 

Think I will jump in with a thought on the Llano Trinity. I'm using mine with a BAT VK3i amp and Vandy 3ASigs. I have tried various tubes in the 12A?7 series and typically found the 12AT7s and AX7s to be a little forward in the upper vocal registers. Since I listen to a lot of female vocalists, that was a problem. Was not impressed with the RCA 7025s or 5751s. If anyone wants to try some of these, send me a private email. So far, the best in my system has been some Amperex Holland 12AU7s. BTW, this amp was much better with the BAT than a CAT SL1 Sig I tried (also now available).
zaikesman
3,017 posts
 
Muralman1, are you certain that the Pass amps contain no resistors in the signal path? Also, I thought the 'Super-Symmetry' topology was implemented prior to the output stage. (I too have not heard of interstage coupling capacitors being referred to as "step-up" capacitors - though I believe they are sometimes called DC-blocking capacitors.)
muralman1
1,527 posts
 
Zaikesman, sorry, that was something I got off of a review a long time ago, and I never bothered to look it up. There are resistors, a few, in line. Resistors are passive.

The two stages of Pass X amps are direct coupled.
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