Ortofon MC A90 cartridge

Dear Tobes: I heard the A90 in my system loaded at 100 Ohms and I don't try it at 47 Ohms.

I can't say if at 47 Ohms or at 100 Ohms has the flatest frequency response, like Pseydor assume, because I don't measured it and I can't calculate either with out the cartridge inductance value.

What I can to know is that passing from 100 Ohms to 47 Ohms the SPL goes down almost 1db and this difference in SPL ( IMHO ) is the one that could makes that we hear " differences " other that a change in the frequency response due that the A90 internal resistance is so low ( 4 Ohms. ).

My thought is that the quality performance does not change but only the SPL. So to evaluate ( other than make the measurements in real time. ) what we are hearing we have to even the Phono stage/line stage output/volume at 47 Ohms and 100 Ohms.
We have to think that our ears/brain are extremely sensitive to tiny/small cganhes on SPL. Many times when we are hearing a recording with two different SPL: normally we like the one that has higher SPL.
In the other side, Pseydor say: " They also become fatiguing after awhile. ", this is correct because at 100 Ohms there is almost 1 db of higher SPL but not ( IMHO ) because is a quality differences other that the higher volume that can affect our perception " after awhile ".
Around 1 db on volume difference makes that the whole system performance change too.

Perhaps a little more important subject about is the input phono stage resistor quality where we are loading that cartridge.

Anyway, if that load impedance is the one value that works in your system that's fine because that value is the one that gives to you music enjoying.

Regards and enjoy the music,
Raul.

Paul, will you be reviewing the A90 at some stage? I'd like to hear your impressions given your enthusiastic review of the Windfeld.

Agree that the 47ohm loading should help prevent any tendency for a rising top octave. In my setup, I think the A90 sounds more transparent at 47ohms - more controlled/sharper transients as well. I can more easily hear how instruments are positioned. I wonder if this has something to do with the (slight) loading of the generator.

Raul, it's not just an SPL change that I'm hearing (see above) - and we are talking about a very small change in level (I think the difference would actually be closer to 0.4dB with the A90's 4ohm generator). In any case, generally there is a tendency to prefer the louder option in A-B comparisons.

I enlisted the help of my 10yo daughter to change input resistance while I listened - it's definitely more than just a level change occurring in my system. I can't duplicate the same 'sound' by adjusting level at the 100ohms setting.
However I agree this may be just a synergy interaction with my particular equipment/setup, as always YMMV.

Dear Tobes: Only to have clear what you posted: +++++" I enlisted the help of my 10yo daughter to change input resistance while I listened.... " +++++

Could I assume that you don't change the preamp volume selector ?

Atr the end the important subject is what you like my question is only to understand about and not to be in controversy or start a controversy.

Regards and enjoy the music,
Raul.

You are correct Raul, I was not adjusting the volume - but like I said this is a very slight volume change.

The details of the sound that I noted above remain consistent at the 47ohm setting - regardless of level - and are not available, to the same extent, at the 100ohm setting (regardless of level).

I do believe my system (phono amp?) may have some preference for lower phono loading of MC's - though the manufacturer of my phono, Plinius, suggest 47Kohms(!) as "a suitable all-round setting" for the M14. I used the Jubilee at 47ohms for a while, though with that cartridge it was less successful and sounded a bit too 'closed in' - so I reverted back to a more conventional 100ohms or even 470ohms.

I may be remembering this incorrectly, but I think it was Jonathan Carr who said some phono amps may prefer lower loading due to noise pickup at the phono input (Jonathan's own phono amp has a fixed high input resistance).

Who knows, it may be taming the HF peak, generator damping or noise pickup....or something else...in the end it's what works best to the individuals ears I suppose.