Phono Amp Capacitor Type Choice.

[gingermrkettle]

What I've found with MC carts is that as the loading value increases:
* there is more 'air' around the instruments
* but at some stage ... the bass loses tightness and becomes loose & floppy

As Blumlein noted way back ago, resistive loading is effectively electromechanical damping of cantilever motion, the lower the resistance the higher the current so the higher the damping effect.

 

[andyr]

As Blumlein noted way back ago, resistive loading is effectively electromechanical damping of cantilever motion, the lower the resistance the higher the current so the higher the damping effect.

And how does that (undoubtedly valuable) research relate to how an MC cart sounds, at different loadings?

Which, shirley ... is the important issue?

 

[gingermrkettle]

Lack of air and space = overdamped by too low a resistance
Loose and wooly bass = underdamped by too high a resistance

 

[andyr]

Lack of air and space = overdamped by too low a resistance
Loose and woolly bass = underdamped by too high a resistance

Aah, OK - thanks.

I can understand that - but it's the first time I've seen a direct relation between loading value and 'air' vs. 'woolly bass'.

It should not be forgotten that Herr Lucaschek ("Mr Benz") makes an MC phono stage which only offers 47k - as he believes his wood-bodied carts sound best with this loading!

 

[sq225917]

He's deaf, critical damping on my Benz lp is 220ohm parallel with 3.3k native circuit.

 

[davidsrsb]

If the generator resistance is 160 Ohms, anything much above 1k is not going to add any damping, so 10k should sound the same as 100k for that. The load resistance does have some effect at the high frequencies, nothing to do with damping.

 

[gingermrkettle]

If the generator resistance is 160 Ohms

Which it won't be for MC carts which is what we were talking about.

 

[davidsrsb]

Which it won't be for MC carts which is what we were talking about.

That's the figure I read for the HOMC DL-110. There is only one way to get > 1mV level output and that's lots of fine wire.
LOMCs are a different ball game.

 

[seyles]

Well, there seems to be a difference of opinion on the resistive loading for the cartridge, from 1K to 16K; I will give it a try with loading plugs and see what I hear (no way of measuring the response and no idea of how to do it).

I have ordered some resistors and capacitors to replace components on the output stage C7 & R10, increasing R10 to 220K to increase the low frequency response, C7 is the same value, but polypropylene.

Hopefully they'll arrive tomorrow and I'll get the soldering iron out.