AudioCircle

Audio/Video Gear and Systems => All Solid State => Topic started by: film on 8 Jun 2023, 11:37 pm

Title: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: film on 8 Jun 2023, 11:37 pm

I recently had the chance to listen to the Axiom II/Walker passive stepped pre in my system, and thought it sounded better than my active tube preamp.

In researching it seems like the best quality passives are autoformers, and the Slagel based units seems to the best one, particularly the silver version.

Has anyone built/used one of these and can comment?

I need a balanced version, if anyone has one of these for sale, or would consider building me one with remote volume, or guiding me to build one, with my basic soldering skills.

Sources are the new PS Audio DSMKII, and Soundsmith Strain Gauge phono pre, going to BHK300 mono amps.

Thanks.

Title: Re: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: jpm on 9 Jun 2023, 01:38 am

Are you seeking information because you want to build one or would you prefer to buy a pre-amp designed around a slagle autoformer? If the latter, you could look for a Vinnie Rossi LIO that has the slagle autoformer volume control.

Title: Re: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: film on 9 Jun 2023, 01:50 am

Thanks for the information.  I am probably looking for a simple build with the silver autoformers, but reading about the LIO is helpful.

Title: Re: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: TomS on 9 Jun 2023, 02:35 am

The Bent Audio "preamps", when they were available, used Dave Slagle's autoformers, both copper and silver versions. They come up for resale on rare occasions, but are quite excellent.

Title: Re: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: mgalusha on 11 Jun 2023, 12:17 am

I have two of the Bent Tap-X preamps that Tom mentions, they are the only components I never think about, they just get out of the way. I also have one in my office system built using his 47 position module.

Dave sells assembled boards with the autoformers mounted, you can ask if he'll do one with 4 modules for balanced, won't be cheap but it would be nice.

Alternatively, there are these: https://www.passivepreamp.com/product/icon-4-pro-balanced/, not inexpensive but supposedly very nice. Instead of switches and relays, they use FET's control the autoformers.

Title: Re: Latest thoughts on Slagel autoformer volume controls/preamps
Post by: Tyson on 11 Jun 2023, 01:28 am

Quote from: mgalusha on 11 Jun 2023, 12:17 am

Alternatively, there are these: https://www.passivepreamp.com/product/icon-4-pro-balanced/, not inexpensive but supposedly very nice. Instead of switches and relays, they use FET's control the autoformers.

I have the single ended version of that preamp and it is indeed very nice.