S'ok, I'll torture it out of you at the Toyster's party
Marco.
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Location: Wrexham, North Wales, UK
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S'ok, I'll torture it out of you at the Toyster's party
Marco.
Main System
Turntable: Heavily-modified Technics SL-1210MK5G [Mike New bearing/ETP platter/Paul Hynes SR7 PSU & reg mods]. Funk Firm APM Achromat/Nagaoka GL-601 Crystal Record Weight/Isonoe feet & boots/Ortofon RS-212D/Denon DL-103GL in Denon PCL-300 headshell with Funk Firm Houdini/Kondo SL-115 pure-silver cartridge leads.
Paul Hynes MC head amp/SR5 PSU. Also modded Lentek head amp/Denon AU-310 SUT.
Other Cartridges: Nippon Columbia (NOS 1987) Denon DL-103. USA-made Shure SC35C with NOS stylus. Goldring G820 with NOS stylus. Shure M55E with NOS stylus.
CD Player: Audiocom-modified Sony X-777ES/DAS-R1 DAC.
Tape Deck: Tandberg TCD 310, fully restored and recalibrated as new, by RDE, plus upgraded with heads from the TCD-420a. Also with matching TM4 Norway microphones.
Preamps: Heavily-modified Croft Charisma-X. LDR Stereo Coffee. Power Amps: Tube Distinctions Copper Amp fitted with Tungsol KT-150s. Quad 306.
Cables & Sundries: Mark Grant HDX1 interconnects and digital coaxial cable, plus Mark Grant 6mm UP-LCOFC Van Damme speaker cable. MCRU 'Ultimate' mains leads. Lehmann clone headphone amp with vintage Koss PRO-4AAA headphones.
Tube Distinctions digital noise filter. VPI HW16.5 record cleaning machine.
Speakers: Tannoy 15MGs in Lockwood cabinets with modified crossovers. 1967 Celestion Ditton 15.
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Trade: Hawk Audio
Location: Ledegem Belgium
Posts: 86
No one having a comment on that cathode follower? At higher output it will distort (the same with emitter followers of course).
IMHO the bandwidth is rather small and he didn't measure distortion at (very) low and high frequencies.
John
Music is an emotional experience. Without it, living would be a dull habit...
Senior Member
Posts: 112
Well, IMO a 12AX7 makes a crap cathode follower. A high-Gm Pentode is much better, I feel.Originally Posted by johnrtd
Trade: Hawk Audio
Location: Ledegem Belgium
Posts: 86
We use a cathode follower with the intention of having a low impedance at the output. This works fine but, having a resistor in series between cathode and ground, the current will vary with the signal. So the tube is "swaying" along its curves when a signal is fed through. Those curves are not really linear and distortion will be the result.
A good thing then is to use a constant current source instead of that resistor. That current source could be a tube or a transistor. When using a tube the Lofton-White follower comes into the picture. The latter has an output impedance <500 Ohm.
Another way to achieve a low output impedance is using a kind of SRPP or Mu-follower. That gives an output impedance of around 1 - 1,5 kOhm and very low distortion. If the interlinks are shorter then, say, 5 meters the signal will stay linear up to around 500 kHz.
John
Music is an emotional experience. Without it, living would be a dull habit...
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