MC and MM Resistor and Capacitor Loading - Page 3

sakellogg · 28th November 2012, 02:24 AM

2 pole air gap variable cap 50-200pf for fine ajustment and switches at 200pf incraments for coarse?
same for resistance.

i did this for my xono.

i ended up redoing it stock though, k.i.s.s. princapal proved to be true.

vdi_nenna · 28th November 2012, 02:30 AM

Variable resistors are more noisy compared to fixed metal film.

The Space Egg Corp · 28th November 2012, 03:45 AM

Fixed metal film resistors are more noisy compared to wire-wounds !

Si.

kevinkr · 28th November 2012, 03:56 AM

Quote:

Originally Posted by The Space Egg Corp

Fixed metal film resistors are more noisy compared to wire-wounds !

Si.

True, but the difference is usually quite small particularly if there is no appreciable dc current flowing through the resistor.

oshifis · 28th November 2012, 02:10 PM

What about zero (input) impedance loading a MC cartridge, similar to a DAC I/V converter?

DF96 · 28th November 2012, 02:17 PM

Decent plugs and sockets usually have better contacts than switches: more pressure, better wiping action, larger surface area.

Feeding an MC into a short would probably give you an HF cut due to the cartridge inductance. It might (I'm not sure) also affect the compliance and affect damping.

An MC is quite different from a DAC current output.

vdi_nenna · 02:36 PM

Quote:

What about zero (input) impedance loading a MC cartridge

I think the cart needs a buffer for back EMF. Kind of like when a speaker pushes a signal back to the amp outputs because of the reverse motion of the cone. Needs a dampening factor.

DF96 · 28th November 2012, 03:14 PM

Not really. Mechanical damping is used for cartridges. Extra electrical damping from a low load impedance might be unhelpful. Whether this is the case would depend on how tightly coupled the mechanical and electrical aspects are. In a speaker they are sufficiently coupled that one affects the other; I don't know about a cartridge but I would suspect the coupling is smaller as efficiency is less of an issue.

vdi_nenna · 28th November 2012, 03:33 PM

Quote:

One common mistake is to add mechanical damping to the turntable/tonearm system without first considering electrical optimization to address the brightness and high-frequency. The problem with this approach is that the transient and decay of musical notes are affected by mechanical over-damping.

Discussion on MC Cartridge Loading

The Space Egg Corp · 28th November 2012, 04:35 PM

Nice link Vince !

I have to say...
...having recently read Morgan Jones's enlightening description of 'resistor production techniques' in his exellent book 'Valve Amplifiers'...
...my current 'anxiety dreams' all concern resistors, not parallel position switches.

Having dumped 'banana plugs' years ago...
...in favour of the superb 'Neutrik Speakon' connectors...
...I couldn't agree more about 'contact pressure', especially in the signal path.
( heavy currents here, of course )

Also as a user of the equally superb Audio Synthesis DIY built PA-138 stepped-attenuator...
...which has a number of switch-contacts in the signal-path...
...the anxiety level caused by this & the long-serving speaker-cables...
...remains firmly at the bottom of my list of 'system-worries'.
( system sounds good; ALWAYS room for improvement though; we think )

Si.

28th November 2012, 02:24 AM	#21
sakellogg diyAudio Member Join Date: Nov 2008 Location: dixon ill	2 pole air gap variable cap 50-200pf for fine ajustment and switches at 200pf incraments for coarse? same for resistance. i did this for my xono. i ended up redoing it stock though, k.i.s.s. princapal proved to be true. __________________ I'm not crazy, my mother had me tested

28th November 2012, 02:30 AM	#22
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA Blog Entries: 1	Variable resistors are more noisy compared to fixed metal film. __________________ I build, therefore I am.

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28th November 2012, 03:45 AM	#23
The Space Egg Corp diyAudio Member Join Date: Sep 2010 Location: London & Miami Blog Entries: 13	Fixed metal film resistors are more noisy compared to wire-wounds ! Si.

28th November 2012, 02:10 PM	#25
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	What about zero (input) impedance loading a MC cartridge, similar to a DAC I/V converter?

28th November 2012, 02:17 PM	#26
DF96 diyAudio Member Join Date: May 2007	Decent plugs and sockets usually have better contacts than switches: more pressure, better wiping action, larger surface area. Feeding an MC into a short would probably give you an HF cut due to the cartridge inductance. It might (I'm not sure) also affect the compliance and affect damping. An MC is quite different from a DAC current output.

28th November 2012, 03:14 PM	#28
DF96 diyAudio Member Join Date: May 2007	Not really. Mechanical damping is used for cartridges. Extra electrical damping from a low load impedance might be unhelpful. Whether this is the case would depend on how tightly coupled the mechanical and electrical aspects are. In a speaker they are sufficiently coupled that one affects the other; I don't know about a cartridge but I would suspect the coupling is smaller as efficiency is less of an issue.

28th November 2012, 04:35 PM	#30
The Space Egg Corp diyAudio Member Join Date: Sep 2010 Location: London & Miami Blog Entries: 13	Nice link Vince ! I have to say... ...having recently read Morgan Jones's enlightening description of 'resistor production techniques' in his exellent book 'Valve Amplifiers'... ...my current 'anxiety dreams' all concern resistors, not parallel position switches. Having dumped 'banana plugs' years ago... ...in favour of the superb 'Neutrik Speakon' connectors... ...I couldn't agree more about 'contact pressure', especially in the signal path. ( heavy currents here, of course ) Also as a user of the equally superb Audio Synthesis DIY built PA-138 stepped-attenuator... ...which has a number of switch-contacts in the signal-path... ...the anxiety level caused by this & the long-serving speaker-cables... ...remains firmly at the bottom of my list of 'system-worries'. ( system sounds good; ALWAYS room for improvement though; we think ) Si.