2. amps-preamps
  3. 131040-1601

PREAMP technology shift? - Class A/ balanced/ dual-mono/ zero feedback vs. op-amp preamps

Hi all,

Even ten years ago, it seemed that the gold standard for solid-state pre's was some combination of the following: Class A/ balanced/ dual-mono/ zero feedback or local feedback. Recently, I'm seeing a range of well-reviewed preamps, from Schiit to Rowland, that use new, high-quality op-amps in their circuitry, to the extent that I wonder if op-amp technology, and chip manufacture in general, has gotten so good that some of the tried and true markers of quality (MOSFETs, Class A circuits) are not in the market except at the highest end, and even then, see also Jeff Rowland. Or is it that manufacturers are looking to less power hungry designs (I know that Rowland was concerned with meeting EU efficiency requirements in its latest designs) and so avoid Class A, for example? Does balanced/ dual mono seem less popular because separates are now less popular than integrateds? Have we reached a tipping point with op amps?

Here's a more focused question. I have invested in a 90s era Aragon 8008BB dual mono balanced amp, but i have an early 90s B&K PRO10-MC that I want to upgrade. Is a Schiit Freya a significant step up, or should I save my pennies for a used, more recent example of the old school: Classe CP500, Pass Labs Aleph or X2.5, or a good example of a newer approach, the Rowland Capri. Speakers are Vandersteen 2CE Sigs. Input impedance of the Aragon is 44 kOhms. 

The tube route is always possible, but I like the idea of a no-fuss, very clean ss, valuing sound stage and detail over warmth, which makes me think I'd be wasting my time with the Freya (any shoutouts for its JFET stage?)

Thanks for letting me wonder aloud!

Paul


paulburnett

Showing 4 responses by paulburnett

paulburnett OP
49 posts
 
This is a great discussion, and I am grateful for all of the advice and opinions. Concerning impedance matching: I know about the 20x rule of thumb for input impedance of the amp over the output impedance of the preamp. If the dividend is in the ballpark, does the impedance ratio really matter to the sound? What does a low or high ratio roughly within the "20 times ballpark" sound like? 

I shouldn't rule out tubes. I've never A/Bed good tubes vs. good solid state in my system, and I probably should. I just know I would be neurotic about swapping out tubes, worrying about when to do so. It's bad enough worrying about needles! ha ha

 
paulburnett OP
49 posts
 
Twist!  I just found out that the Schiit Freya is only balanced out from the tube stage, and further, that my Aragon 8008BB shorts the balanced input when using single-ended (jumpers in place on the balanced ins if using RCA), which means I would really need to love only the tube stage and never use either the passive or jfet buffer. It's a bit of a baffling design choice. I guess Mike Moffat really love his tubes. And yet, many tube-only preamps are also single-ended only. 

Will Schiit ever consider making a  fancier pre that's balanced all the way? Throw the Mani's guts into a shielded corner? I'd pay a fair bit more for that. 

In the meantime, now back looking at balanced SS. 
paulburnett OP
49 posts
 
Hi Ghosthouse,

I agree with your interpretation. I have a balanced amp that accepts either balanced or RCA, but not both at the same time. I listen to vinyl 50/50 with digital, the former of which comes in single-ended. I was looking forward to being free to listen in tube, jfet, or passive, but if I understand correctly that's not an option if I run balanced to the amp, which is what I want to do. If Schiit has options other than running RCA to the amp or listening through tube stage only, I will be excited to hear what you learn. 

Thank you,
 
Paul
paulburnett OP
49 posts
 
Sorry all,

here is jason stoddard explaining what I was trying to find out: https://www.head-fi.org/threads/schiit-happened-the-story-of-the-worlds-most-improbable-start-up.701...

so you get sound from all modes, passive, jfet, and tube, but only balanced thru tube stage. Fair enough! 
More to discover