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Analogue Sources: Nottingham Analogue Studio Space Deck driven by Walker Audio Precision Motor Controller. Woody® Arm from Pete Riggle Audio. Dynavector 17D2MKII, Dynavector 20xl, Denon 103, Audio Technica OC9 cartridges
Digital Sources: Wavelength Audio Cosecant USB DAC v3 (Transcendental16/44.1 DAC module) fed by iBook G4 with dual 500GB LaCie Firewire drives; Tube Research Labs fully modified Sony SCD-2000ES (for SACD playback).
Secondary: TRL-modified Alesis ML-9600 high-resolution master disk recorder
Preamps: deHavilland UltraVerve, professionally-modified/upgraded Eastern Electric Minimax (larger PS, 12FQ7 ready, gain cut to 9dB); self-modified Jolida JD-9A, Herron Audio VTPH-1MC and Monolithic Sound PS-1/HC-1 phono stages.
Amplifiers: Wright Sound Company WPA 3.5 monos and AudioSector AMP-1 integrated amplifier. Secondary: Outlaw Audio RetroReceiver.
Speakers: DIY Altec 604 MLTL. Secondary: Zu Audio Druid Mk.4; Sound Dynamics RTS-3; REL Strata III
Cables: Cardas, DIY WM-XTC, Audience and Zu Audio Libtec cables; Cardas Golden Cross, Audience Au24, Audience Maestro [on loan] and TG Audio Lab custom copper interconnects. Secondary: Analysis Plus cables and
Stands: Two three-tier Grand Prix Audio Monaco units on GPA Apex footers
Isolation: Main: GPA Monaco. Secondary: Lovan Affinity Pro6 Series rack,
Acoustic Dreams Dead Ball Isolators; Neuance platform
Powerline conditioning: BPT 3.5 Signature; cryo'd Pass & Seymour wall
outlets; Audience, T.G. Audio Lab SLVR, Analysis Plus Power Oval, and Zu
Audio Birth and Bok power cords [both on loan]. Secondary: Brick Wall
Sundry accessories: HAL-O® Vacuum Tube Dampers, Herbie's Way Excellent
Turntable Mat, VPI 16.5 record cleaner, Shun Mook Valve Resonators, Auric
Illuminator, and Walker Audio Vivid CD & DVD Enhancer
Music makers: Epiphone Dot (Gibson ES-335 knock-off) and Chet Atkins CE
(nylon-strung classical) electric guitars; Fender Blues Jr. amp; Privia PX-555
keyboard and 1906 Ellington upright piano.
Office system: Soundquest R601 Tube Hi-Fi FM/AM Classic Radio and a
Gibson J-100 acoustic guitar
Room size & treatments: 26' x 19' x 9' (a fractured 'L', nominally 16' x 19' with
12' feet of the 19-foot dimension opening to the 20-foot section of the 20' x 12'
kitchen/eat-in area); concrete slab, sheet rock walls. ASC Tube Traps and
Sound Planks, Echo Busters absorbers, Shakti Hallograph Soundfield
Optimizers and Acoustic Revive RR-77 Ultra Low-Frequency Pulse Generator
Review component retail: $895
Do your job.
The Sowter SUT from Bob’s Devices is a hand-crafted moving coil
cartridge step-up transformer built with Sowter 1951 transformers and
Cardas connectors in a hand-polished double powder-coated cast aluminum
enclosure. A ground/lift switch is included and works exactly as
it should. The Sowter 1951 is custom manufactured to Bob’s
specifications. It’s a 1:20 (26dB) step up audio transformer switchable to
1:10 (20dB) built with OCC wire.
And as Henry Ford famously said in his remarks about the 1909 Model T,
any customer can have [one] painted any color that he wants so long as it is
Bob is Bob Sattin. He’s a tremendously nice guy.
It starts like this via email:
"As you know one size does not fit all. I treat each of my customers as an
individual and ask what equipment they have and what they may
intend to purchase. Then I make a recommendation about which of my
products—if any—they should use. What sounds great with some setups
sounds less than acceptable with others. So it depends on what we are
matching as to what I will send you for an audition. Please tell me what
cartridge(s) and phono stage you will be using for testing purposes."
So I do. I tell him that I recently tried using my Dynavector 17D with the
Allnic phono stage instead of my hot-modded Jolida because the Allnic is
smoother overall. The sound was good but seemed to be missing some of
the gain, dynamics and top end that were available with the Dynavector 20X.
The Allnic and 20X (with 5 ohms internal resistance) were simpatico since
the 20X wanted to see 30 ohms of load impedance. The 17D (38 ohms
internal resistance) has a recommended load impedance of 100 ohms.
Because the H-1200 manual stated that the step-up transformer in the
H-1200 can accept cartridges with up to 300 ohms internal impedance, I
thought they might sync up. They didn’t. And here’s why:
Bob does the math and Stephæn gets a lesson
"Although the 17D2 MkII has .23mV of output and the internal impedance
is 38 ohms, Dynavector recommends a load of at least 100 ohms for that
cartridge. What happens with impedance is that if you have too much
reflected impedance from the preamp, it 'chokes' the cartridge a bit and
you lose the high-frequency clarity. I have personally found that the ideal
match is at around 10 times the internal impedance of the cartridge, which
in this case would be 380 ohms. So with your preamp MM section at 47k
ohms, working backwards to get 380 ohms of loading you would need a
step-up of no more than 1:11. Typically we find 1:10 SUTs and not 1:11
so at 1:10 that is 20dB and your effective output to the phono preamp
would be 2.3mV. That's a bit low. With the 1:40 internal transformers in
your preamp, the reflected impedance would be 30 ohms. This means you'd want a cartridge with no more than 3 ohms internal
impedance. There is no way the 17D3 will work properly with the
Allnic internal MC section without it losing its high-frequency sparkle.
researched Allnic's manual and found that they recommend a cartridge of
no more than 30 ohms. That does match the reflected impedance. But what
Allnic didn’t figure was the overhead needed by the cartridge. Where it says
it will match a cartridge of 30 ohms, it really means that it will match a
cartridge which wants to see 30 ohms. Yours wants to see at least 100 ohms.
Having said all that—and I hope it makes sense to you—I cannot provide you
with a SUT that will work properly in your system; and according to the
physics no one else can either."
Bob is honest. I’m not so bright. But, at least he didn’t come right out and say it.
I told you he was tremendously nice. Plus Bob wants what’s best for his
customers. He continues: "I can however improve over what you have by
providing a lower gain of SUT. It will be less loud than the one you
have but sound better. A 1:20 step-up is what I would recommend. That is about 26dB of gain and would give you an output of 4.6mV, about
the same as a standard MM cartridge. Does that make sense to you?"
Yup. I had screwed up with the 17D by setting the manual aside and then
mentally transposing the internal impedance for the load impedance figure.
Result? Not so simpatico.
Lots of good info there Bob. Thank you for your efforts to educate me.
What you say goes a long way to explaining why the Dynavector did not
sound quite like I expected.
"So let’s give it a shot," says he. "I do have a Sowter at 1:20 here, which
will match your cartridge well. It is one that I had custom made to use
OCC wire and a taller can. You can read about it here."
Al-righty then. Please send it to my office so that a carbon-based life form
can sign for it.