mc cartridges- what do i have to do?

alexone · « **on:** 13 Oct 2009, 08:52 am »

hi!

i'd like to buy a new mc cartridge. my problem is that i am not sure which one fits my set up.

my system:
- Acoustic Signature (Final Tool) TT
- Rega 300
- Bryston BP 1.5 phono pre

the phono pre uses a step up transformer with additional gain of 22.5 db. according to Bryston's user manual this setting accomodates mc cartridges below 40 ohm. there is also a setting of 16.5 db available for cartridges of 40 to 150 ohm output impedance.

my question:
let's say the internal impedance (dc resistance) of a mc cartridge is 6 ohm. is it correct that the phono pre's setting in this case HAS to be around 10 times of the cartridge's internal impedance? speaking of 6 ohm it would be 60 ohm...
someone told me that this is a "golden thumb rule". he also said that i can use (almost) any mc cartridge but the only thing that i have to know is that the frequency's linearity might not be given anymore if the upper "rule" is not applied.

what general recommendation can be given for a mc cartridge regarding my preamp?

any input is welcome. thanx a lot.

al.

TheChairGuy · « **Reply #1 on:** 13 Oct 2009, 11:56 am »

Quote from: alexone on 13 Oct 2009, 08:52 am

my question:
let's say the internal impedance (dc resistance) of a mc cartridge is 6 ohm. is it correct that the phono pre's setting in this case HAS to be around 10 times of the cartridge's internal impedance? speaking of 6 ohm it would be 60 ohm...
someone told me that this is a "golden thumb rule". he also said that i can use (almost) any mc cartridge but the only thing that i have to know is that the frequency's linearity might not be given anymore if the upper "rule" is not applied.

I've heard the same 'golden rule'...but, it's more a guideline than rule. Actually what I've heard is 10-20x the internal impedance....20x is closer to what I've found.

But, the internal impedance doesn't really translate electrically to 10 or 20x...its just what many audiophools have come up with in the end.

It's actually more of a crapshoot than 10 or 20x.....but, it's a good place to begin (and hopefully find that it works as advertised)

The 'loading' point has really more to do with internal inductance, tip resonance point and a few other factors neither I nor most of the more technical folks can add up. In the end, resistively loading a cartridge is a fancy equalizer or tone control and subject to individual needs more so than scientific basis.

Hope that didn't make things more confusing

John

alexone · « **Reply #2 on:** 15 Oct 2009, 11:31 am »

ok. thank you ChairGuy!

al.

TheChairGuy · « **Reply #3 on:** 15 Oct 2009, 01:23 pm »

Quote from: alexone on 15 Oct 2009, 11:31 am

ok. thank you ChairGuy!

al.

You're welcome.

Basically, experimentation will yield the best results for anyone. But, the general recommendation of 10-20x is often pretty close to what you might find as 'ideal'

It's a subjective matter - as are so many in hifi.

Regards, John

analognut · « **Reply #4 on:** 16 Oct 2009, 02:52 am »

Quote from: alexone on 13 Oct 2009, 08:52 am

what general recommendation can be given for a mc cartridge regarding my preamp?

The most direct answer I have for your question is very simple and I didn't see anyone encouraging this, so here goes:

Follow the manufacturers recommendation for cartridge loading! Output will drop as you decrease the resistive loading, but the sound will smooth out. I have a Denon DL-103R and a AT-OC9ML/II and I get the best results for both of them by following the mfr's recommended minimum load impedance. My experience was that with both of them it became much easier to hear the sound of small changes in resistive loading after the carts were fully broken in. For instance, with AT-OC9ML/II I can easily hear the difference between a 20ohm load and a 39 ohm load.

alexone · « **Reply #5 on:** 23 Oct 2009, 03:27 pm »

Quote from: analognut on 16 Oct 2009, 02:52 am

Quote from: alexone on 13 Oct 2009, 08:52 am
what general recommendation can be given for a mc cartridge regarding my preamp?

The most direct answer I have for your question is very simple and I didn't see anyone encouraging this, so here goes:

Follow the manufacturers recommendation for cartridge loading! Output will drop as you decrease the resistive loading, but the sound will smooth out. I have a Denon DL-103R and a AT-OC9ML/II and I get the best results for both of them by following the mfr's recommended minimum load impedance. My experience was that with both of them it became much easier to hear the sound of small changes in resistive loading after the carts were fully broken in. For instance, with AT-OC9ML/II I can easily hear the difference between a 20ohm load and a 39 ohm load.

thanks, analognut.

al.

JuanR · « **Reply #6 on:** 6 Nov 2009, 03:21 pm »

Analognut, I have the same cartridge (denon-103R) that the output is .25mv, impedance 14 ohms. my preamp (Kora Eclipse) mc input 0,4mV/100 ohms and the mm input is 4mV/47k. In your opinion which input will work better if any?

toobluvr · « **Reply #7 on:** 6 Nov 2009, 03:50 pm »

Quote from: JuanR on 6 Nov 2009, 03:21 pm

Analognut, I have the same cartridge (denon-103R) that the output is .25mv, impedance 14 ohms. my preamp (Kora Eclipse) mc input 0,4mV/100 ohms and the mm input is 4mV/47k. In your opinion which input will work better if any?

.25 mV is pretty low output. For correct gain, you really have no choice in the matter. You must use your MC input.

Whether this input loads the cartridge correctly, I have no idea. Simply try it and see. If things sound balanced and "right", don't worry about it. Just enjoy the music.