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Preamp for a GaN-FET amp...

Hello everyone... I'm thinking of replacing my Belles Aria Integrated for a GaN-Fet amp. I would have preferred to purchase an integrated GaN-Fet, but they are either too expensive or of questionable quality. I therefore resign myself to opting for an amp/preamp combo. My question is the following :

Which preamp do you recommend for a GaN-Fet amp?

I haven't made my choice yet, but the only GaN-Fet amp within my reach is the Starkrimson (used). Please note that if I opt for GaN-Fet, it is to avoid tubes, so I would prefer a preamp WITHOUT tube (and not a class A).

My speakers are Altec 620A (100 db efficiency) and I mainly listen to digital sources through a Metrum DAC. I also sometimes listen to records on my Garrard 401... That's basically why I need a preamp.

Note: the Belles Aria Integrated is a superb machine with astonishing sound, but I'm looking for an amp whose midrange is as good as a tube. The Altec don't do any favors and they are a little harsh in the midrange, especially at high volume. For those who would like to understand what I am trying to express by "as good as a tube", I suggest you listen to this interview with Ralph Karsten who explains the limits of transistors much better than me.

Thank you ! 😎

128x128alaindexe

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
11,615 posts
 

It would seem that while tubes have the preferred distortion ratios, their total distortion is higher than all solid state preamps.  So, what is it that is creating this preference and is this something that solid state preamps can "copy"?

@snapsc I think this is the same issue that has kept tubes alive in the power amplifier arena for so long. By comparison, the solid state preamps I've heard sound less lively and thinner than most tube preamps I've heard. I think this relates to distortion but I've done no measurements one way or the other to confirm this. However, tube preamps tend to be much lower distortion than tube power amplifiers. Solid state preamps tend to be even lower distortion; the 'measurement guys' will have you believe that distortion is so low as to be inaudible.

Tests we've done suggest otherwise until the distortion is below the total range of human hearing, which is about 120dB (so less than -120dB). That is my surmise; a lot more research has to be done in this area and I don't see anyone actually stepping up; the measurement guys say this was all solved 40 years ago yet clearly, it wasn't.

The result of that is tube preamps from 40 or more years ago still sound musical if properly refurbished but solid state preamps from that long ago don't get taken seriously. So I this is the best answer I can give, which is not at all definitive; belief and knowledge being two different things.

atmasphere's avatar
atmasphere
11,615 posts
 

then why isn't GanF also the future of preamps.

@snapsc The issue is technical. The issue is something called Gain Bandwidth Product, which is important in amplifier design, if that design is using feedback. With conventional solid state and tube amps, its very difficult to get enough Gain Bandwidth Product to do the job needed. Class D offers a method of getting around that problem- and that's why some of them are sounding very musical.

But in a preamp, you can use opamps, which have had the values of GBP for a long time. So while a class D GaNFET preamp could certainly be made, there's not nearly the incentive from a designer's point of view.

atmasphere's avatar
atmasphere
11,615 posts
 

@alaindexe I get trying to move away from tubes. But I think you'll find that the common wisdom is still to use a tube preamp with the solid state (in this case, GaNFET class D) amp. Our class D is designed to be easy to drive with any kind of preamp.

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