2. amps-preamps
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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
paulburnett OP
42 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. 
atmasphere's avatar
atmasphere
11,662 posts
 
Why? There are fully balanced/differential tube line sections available.
ghosthouse's avatar
ghosthouse
4,300 posts
 
@paulburnett 
"...the Schiit Freya is only balanced out from the tube stage...."

Paul - I'm not sure that accurately represents Freya functionality.  
There might be some confusion based on a statement in the Freya manual.  See the Freya connections page and this note under "2. Single-Ended Inputs"...

Note: Freya does not convert single-ended to balanced, except when using the tube gain stage.

My understanding is that this statement applies to single ended inputs only.  If you are using a singled ended connection from source to Freya with only a balanced connection from Freya to a power amp, you won't get sound except in tube mode.  

I have asked Schiit for confirmation.   

In my experience, balanced sources connected via XLR work fine using the Freya's balanced out connection whether running Freya in Passive, JFET or tube mode.  

paulburnett OP
42 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
ghosthouse's avatar
ghosthouse
4,300 posts
 
Hello again Paul - @paulburnett 

Own a Freya myself and might have a similar set up.  Phono pre for vinyl is singled ended; digital (DAC & CDP) is balanced - so there are singled ended and balanced inputs to the Freya.  The Taranis power amp is balanced only.  Freya connects to it via an XLR IC.  I switched out the Taranis (just for a change of pace) a little while ago but I was definitely able to listen to digital (Bal. in) with Freya in JFET mode and and switch to vinyl (SE in) using Freya in tube mode all while being connected via XLR only from Freya to the balanced input of the Taranis.  

I do NOT recall whether I got sound from the SE/vinyl input if I tried to listen in anything but tube mode. Not sure I tried.   Apologies if I'm being a little dense and missing your point.  I don't mind re-installing the Taranis to confirm things if this will address your concern.  Let me know. 




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