Home Visit: Intact Audio Autoformer Preamp
Letter from NYC (71) 2017(10)
Regular readers of this blog will have read about my friend Robin the Scot, who now lives in Taipei. Those who don't can read about his setup in my visit last year. Robin and I share remarkably similar musical and audio preferences and he uses a R2R deck! I just got an email from him. As usual, his writing is thorough and worthy of publishing, so here it is below. Around the same time in NYC I paid a brief visit to reader Richard, who also employs an Autoformer Preamp in his system, hence I here group these two disparate articles together.
Home Visit: Slagle Autoformer Preamp
Reader Richard first encountered my Blog after he acquired a Nagatron cartridge. I rarely venture into town these days but last Sunday I managed to pay him a belated, though brief visit. Richard likes to build things, so naturally has a DIY bent and is obviously a tweaker who has spent a lot of time adjusting his system. He system is rather complex:
Analog Front End: Technics SP10 MK2; Tone arm 12" Ortofon AS212 (modified by Alfred Borkland); Cartridge Glanz MFG 610 LX.
SUT: Technics SH-305MC
Phonoamp: iFi iphono 2 (used as MM).
Digital (CAS): Mac Mini, Focusrite red net 3, Antelope live clock, Mutec mc3+usb reclock,
Metrum Octave dac, Player software Chanel D Pure Music.
Preamp: DIY passive pre with Bent audio Tap X autoformer volume controls by Dave Slagle
Amp: Ben Jacoby modified VTL compact 100 mono blocks running 2 KT120 tubes ea.
Loudspeakers: Custom Ohm Walsh 2.2000
Subwoofer System: DSPeaker antimode 2.0 for DSP room correction of 4 REL Q201e subwoofers
Richard's Living Room is typical of a medium sized NY apartment, with a layout not particularly advantageous for audio. Obviously a family man, the room is stuffed with heirloom furniture. Obviously a considerate person, the audio is laid out along the long wall with the loudspeakers minimally in-room. In HK's small apartments I also see a lot of setups placed this way.
Yet the sound (from both CAS and Analog) was quite enjoyable, smooth yet detailed. Note R's Ohm's are custom, that is truncated at the bottom, in height as well as frequency response, nothing below 50 Hz, where the DSP'ed distributed subwoofer systems take control.
I am not a fan of CAS, but this (complex) one is definitely one of the better ones I have heard. The TT is the mighty Technics SP-10, one of my favs, and the rare Glanz cartridge seems like an unusually detailed MM, in the vein of my Shelter 201.
Most interesting to me, of course, is the Autoformer Preamp. David Slagle's designs are rather famous, heard here in a Bent Audio variation, but Intact Audio sells direct for DIY'ers, and there are other companies, like the very expensive Vinnie Rossi, that employ his autoformers. Although I am a horn user and personally prioritize the "jump factor" and hence don't prefer passive preamps of any kind, I do have a keen interest in their use as buffer amps. Given my recent experience with Schiit Saga, I was particularly interested. I was not disappointed. I think in the future if I have time I'd DIY an autoformer preamp to use as a buffer amp.