Bent Audio Slagleformers: my passive preamp endgame
- Thread starter Redboy
- Start date
I recently had the good fortune to buy a set of unbuilt Slagleformer modules on the secondary market, so I built another one of these with the same panels and parts. It's basically identical to the other, but this one has the standard copper autoformers.
My pal Gary's gonna give this a whirl in his system soon. I'll be interested to hear how he likes it!
My pal Gary's gonna give this a whirl in his system soon. I'll be interested to hear how he likes it!
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True. Gary's got good ears and has always told it like it is, so that's what I'm looking forward to.
It has performed flawlessly since I put it in the system, and it is by far the most transparent, colorless passive device I have tried. In the past I've used high end potentiometers, shunted pots, SMD stepped attenuators (DACT) and other TVC/AVC devices from the likes of S&B, Prometheus and Silk; the Slagle iron at the heart of these modules remains at the top of the heap.
John Chapman's implementation takes those magic modules and adds the convenience of remote control of volume, balance and mute.
In short, I LOVE this thing and I don't foresee moving it out of the system anytime soon.
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There is a lot to be said for circuit simplicity with regard to line stages. I sometimes wonder how ultra high prices preamps justify their existence given the attainment of some very simple stages. It doesn't take much consideration to conclude that the less circuitry the signal can successfully traverse, the less trammeled the signal will be.
Sometimes it seems that it takes the audio world 20 or 30 years to catch up with the trailblazers.
Sometimes it seems that it takes the audio world 20 or 30 years to catch up with the trailblazers.
Joe Roberts
Agent Provocateur
That's partially because it is nickel...not iron!
At "work" we tried everything, looking for the finest, cost no object option, , up to $6k retail German silver litz TVCs on nano cores, and we settled on silver Slagleformers as the best all around option we could get.
Hey, mebbe I was using the word "iron" in the colloquial sense... like Kleenex, or something. Didja think of that, Mr. Smartypants?
Joe's right, of course. He's right a lot.
Some of those fancy Hitachi cores still intrigue me... I'll probably have to build some up someday, just to get it out of my head.
You can guarantee that the Military would have found something better, but that won't filter down to civilian life for another 50 years or so.
Joe Roberts
Agent Provocateur
I got to hear the same transformer (foil secondary output transformer) on Finemet and our "standard" nickel core, with copper wire/silver coated foil, copper wire/pure silver foil, and silver primary/pure silver foil secondary.
These were wound on special large cores we got directly from Hitachi Japan. Amps were SE 300B with a low distortion current feedback driver stage.
I must say that the Finemet cores were a little too much on the soft side for me. They have an amazing rich quality through the lower mids and somehow sound very dense and solid yet open with tons of low level detail, but left me wanting a bit more cut and snap. This was especially true of the all silver version. I thought the copper primary/silver foil unit was the best compromise.
i was in the minority though. Most people in the room liked the full-on silver Finemet version, but I was probably the only blues harp player in the crowd.
I spent a week + hanging with Slagle and his partner in crime Jeffrey Jackson at the DC show and ETF in Denmark and discussed cores to some degree. They seemed to agree with each other that nickel still rules for low level work but the nano/Finemet stuff comes into its own for output "iron." More like output "glass" really...
I think Dave can wind slagleformers on nano if somebody insists, but I think he would recommend nickel.
Finemet really is amazing stuff by the spec sheet. Saturation resistant, high perm. I'm thinking that it requires special care in implementation, though.
There are also many grades and sources for what is being passed off as Finemet. Some Finemet-ish cores are closer to "Metglas," which I think in general is less high perm and more saturation resistant, targeted for high efficiency power cores.
These were wound on special large cores we got directly from Hitachi Japan. Amps were SE 300B with a low distortion current feedback driver stage.
I must say that the Finemet cores were a little too much on the soft side for me. They have an amazing rich quality through the lower mids and somehow sound very dense and solid yet open with tons of low level detail, but left me wanting a bit more cut and snap. This was especially true of the all silver version. I thought the copper primary/silver foil unit was the best compromise.
i was in the minority though. Most people in the room liked the full-on silver Finemet version, but I was probably the only blues harp player in the crowd.
I spent a week + hanging with Slagle and his partner in crime Jeffrey Jackson at the DC show and ETF in Denmark and discussed cores to some degree. They seemed to agree with each other that nickel still rules for low level work but the nano/Finemet stuff comes into its own for output "iron." More like output "glass" really...
I think Dave can wind slagleformers on nano if somebody insists, but I think he would recommend nickel.
Finemet really is amazing stuff by the spec sheet. Saturation resistant, high perm. I'm thinking that it requires special care in implementation, though.
There are also many grades and sources for what is being passed off as Finemet. Some Finemet-ish cores are closer to "Metglas," which I think in general is less high perm and more saturation resistant, targeted for high efficiency power cores.
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Vintage999
Active Member
The first time I was able to hear an "autoformer" based passive, I flipped out. My complaint against passives prior to that was a lack of dynamic slam and energy - everything else was great. The autoformer passive had everything I needed dynamically along with gorgeous tones and tone color. I purchased a Sonic Euphoria and have been very happy with it. A permanent place in my preamplifier rotation.
Good listening...
Good listening...
That's one I haven't heard, but it looks like a nice bit of kit!
DeeCee
"Music is what we like to play..."
I like mine too! In fact, I like mine so much, I did something I rarely do - I created a review:
https://www.audioasylum.com/reviews/Preamplifier-SS/Sonic-Euphoria/PLC/amp/97587.html
Unfortunately, the remote control modules are no longer available to DIYers, but you can still get the Dave Slagle magic from Intact Audio here:
http://www.intactaudio.com/atten.html
Vintage999
Active Member
DeeCee...nice review! You captured my thoughts on the Sonic Euphoria perfectly - a transparent window back to the original performance. And the review was very well written!
Good listening...
Good listening...
DeeCee
"Music is what we like to play..."
Thanks! I appreciate that!
