In Reply to: Then questions posted by Gordon Rankin on October 30, 2003 at 07:41:12:
Hi, it's a honor to receive a post from THE Gordon Rankin.My autoformers, which are custom wound by David Slagle, work perfectly on any power amp with an input impedance higher than 10 K ohms. That's at maximum volume, which is the worst case scenario.
Also, restacking the laminations to reduce the gap will make the autoformer work perfectly into lower impedances like 5 K (e.g. Pass amplifiers).
As one decreases the volume, the CDP's reflected output impedance will go down as a function of the square of the turns ratio.
A typical CDP output impedance of 100-200 ohms will most of the time behave as 10 ohms source driving 10,000 ohms load, an almost ideal impedance ratio (anything above 10:1 is fine, in my preamp it's 1000:1).
Autoformers perform attenuation in two ways: ratio of inductive reactances and ratio of coil resistance. There is a direct DC path between input and output, which IMO makes a whole lot of difference.
My system goes flat in-room to 20 Hz, my tubed CDP outputs 7 Volts, I have never heard any signs of bass roloff or saturation at any decent volume setting.
Some TVCs do saturate above 5-6 V input at very low frequencies. There's a white paper on S&B's site with frequency x distortion charts, therefore you are correct on the inductance issue, it happens, but not with Dave's autoformers.
All the best
Carlos
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Follow Ups
- Re: Then questions - Carlos 10/30/0313:14:26 10/30/03 (10)
- Corrections & more questions - Gordon Rankin 08:01:05 10/31/03 (9)
- phase error - Donald North 17:02:54 10/31/03 (8)
- Donald Thanks... - Gordon Rankin 13:31:57 11/3/03 (0)
- Re: phase error - dave slagle 10:00:50 11/3/03 (6)
- Re: phase error - mqracing 08:32:15 11/17/03 (1)
- Re: phase error - Roscoe Primrose 13:26:59 01/7/04 (0)
- Is 1K the center of the musical universe? - mqracing 08:07:51 11/17/03 (3)
- No. 980 Hz is. - Dave Cigna 12:38:19 11/18/03 (0)
- (Middle C is 261.6Hz, the A above it is 440Hz) [nt] - Ted Smith 11:11:17 11/17/03 (1)
- thanks Ted [nt] - mqracing 12:52:19 11/20/03 (0)