Why would High Output Moving Coil (HOMC) cartridges be bothered by loading with a higher input capacitance? Their output impedance is much lower than MM carts. That puts the pole of the low pass filter formed by output Z and input C higher, and any resonance higher up as well. The Denon DL110 has a coil resistance of 160 ohms, which is much lower than the over 500 ohms from a Shure, etc.
It could be that the cartridge's coil inductance has more of a bearing on whether it will run well into a higher input capacitance. If so, can somebody explain why that is, and how that works?
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so you are saying 12AX7 is OK for MM but not for MC ? - an oversimplification if taken out of context, but taking into account the comments above.
I listen to needledrops posted on other forums, and they are usually at least 16/44.1.
jeff
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Tells us what the system sound is but we can’t compare across systems- if you can post comparisons where everything is the same except for the phono amp ?
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I am amazed that no one has recommended using a 834 clone from F/Bay, With the basic kit, and upgraded to components + star grounding this phono amp can challenge $4000 to $6000 commercial phono amps and can be put together for around $300. Lenco Heaven has several great write up on what to do, yet this site nearly totally ignores it
Cheers & Happy Building
Sy's His Masters Noise is a better one.
I'm planning a couple of cascode projects now and one will be a phono pre. I'd like to try the folded cascode style using a pnp as the "upper" pass device. Just ordered a bunch of 6S4p tubes for this project actually.
Russian 6S4 or European PC86 [at 170V 14mA] make very good RIAA eq stages in Shunt Cascode.
One refinement, that is missing from my previous 'serving suggestion' schematics is an anode stopper resistor: say 330-560Ω 3W wirewound. The tuner triodes can be very susceptible to oscillating without it.
The Shunt Cascode stage gives a current output to drive the EQ network: 2 capacitors, 2 resistors that can do their stuff with zero interference from the ra of the triode - quite an advantage.
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there are plenty of options to address that, one being Merlin's feed-forward (he claims -30dB), the other being a clean supply (yes, that's more complex, but not much). if one uses a clean supply would the cascode then be the preferred approach ?
if you have listened to both, how would you compare them, subjectively speaking ?
I did not listened Kevin stuff but he helped me a lot lowering the input capacitance of Valve Itch with great success so he knows what's doing.
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Kevin gently provided my a table and the way to do it, see the thread Valve Itch post 2699 Valve Itch phono
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One post doesn't illuminate too much for me but if I understand it they are not reducing the capacitance. They are changing the cartridge load resistance to change the Q of the cartridge-preamp-capacitance circuit, cutting down the 'hump' in the treble response at the expense of an earlier roll-off in the treble. Hence, at the end, a lower capacitance will give a more extended frequency response no ?
12AX7 should be a great RIAA tube. however I would do a SS front end > 12AX7 RIAA> SS buffer that should be able to take on any hi end phono preamp and have lower noise as well. The 12AX7 should also have DC heaters.
currently using a single 2SC1815 as an input stage gain of 10 ( noise lower then JFET )
distortion < .01% into op amp RIAA. I used this setup with excellent results as a tape head amp for car stereo back in 1986. the transistor 2N5410 has a gain of 45 and a LF353 performed the NAB eq. s/n 63 db no dolby
currently using a single 2SC1815 as an input stage gain of 10 ( noise lower then JFET )
distortion < .01% into op amp RIAA. I used this setup with excellent results as a tape head amp for car stereo back in 1986. the transistor 2N5410 has a gain of 45 and a LF353 performed the NAB eq. s/n 63 db no dolby
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This describes a technique for measuring input capacitance in the front end of a phono stage. I then suggested how to minimize the strays. (Miller capacitance is a different matter of course)
I use cascodes in the front end of many of my phono stage designs but I am also one of a small cadre of people who like regulated B+ for tube circuits.
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