MC phono stage without transformer?

Dear Ron: I made some research about your audio system items to " figure " ( in some way. ) what are you hearing and why you prefer a SUT.

There are not too much info on your amp but other model where I read that its output impedance is around 4 Ohms, the reviewer write: +++++ " In any event, these values will have a significant audible effect on the amplifier's performance " ++++++

Certainly had an audible effect with almost any speaker and yours has a 4 Ohms nominal impedance that could mean ( I hope I have the real Iroise electrical impedance curve. ) that maybe goes lower than that.

Those facts ( amplifier impedance output and electrical speaker impedance ) tell me with out any doubt that the reproduced sound can/could be heavy " colored " ( for say the least ) due to that impedance mistmatch and in some way to intermodulation speaker distortions due that its crossover ( woofer ) is on the high ( very ) 1200hz range.

It is probably too that the real inverse RIAA eq. deviation on your Preamp ( that makes a paramount difference in the quality performance. ) is bigger than 0.5 db ( maybe around 1 db. ), this can/could tell me that here the reproduced sound is/comes highly full of colorations and we have to remember too that the signal pass through a SUT where exist additional signal degradation.

Now, I understand that those colorations ( any audio system have in high/low manner. ) are the best for you ( nothing wrong with that ) but that could does not means is " correct " against what is on the recording or to a live event.

I prefer like you that an audio system be " emotional " ( just like music is. )but I like at the same time that have at least to other " vitues " : neutrality ( not analytical ) and " credible " whole tonal balance from top to bottom.

Regards and enjoy the music.
Raul.

Eldartford, of course no-one should be surprised that I don't like transformers :)

I did, however, outline some of the difficulties that one faces, bandwidth, ringing (distortion) and hysteresis losses (yet another kind of distortion).

You can dance through the parameters, trying to dodge the silver bullet and some good compromise is available. For example, by sacrificing a little LF bandwidth, you can reduce hysteresis losses, but they will still be there. Ultimately you are still dealing with a compromise.

This is not to say that a phono section with enough gain to start with does not represent some sort of compromise. For example, I prefer the sound of tubes, and tubes have a reputation of making more noise. What I found is that you have to treat the tubes the same way you treat transistors: fully-differential, with proper constant current sources, in order to make them be quiet. I found that making the proper constant current source was a huge part of that recipe.

So- we can get them to be quiet enough with the lowest output cartridges and at the same time the phono section is easily transparent enough to easily hear the insertion of the best SUTs we can lay our hands on. Now we all know that at the phono input, connections are very critical so for our evaluations we had to solder everything in. What seems to be coming out of this is that the more complexity, the less bandwidth and the less transparency.

So we endeavored to build a simple phono section. It has only two stages of gain and employs differential passive EQ. I don't know how much simpler it can get, in fact I've seen a lot of MM stages that have more complexity.

I guess the point is that my dislike of transformers is not **just** because I'm an OTL manufacturer, it really stems out of having worked with audio transformers a lot (and while they have always had some nice advantages, such as ground isolation): they always have an audible artifact. I really wish they did not, but there appears to be nothing that can be done to change that. You just have to avoid them if you can, that's all.

...the more complexity, the less bandwidth and the less transparency

Words of wisdom!

Rauliruegas...The Signet transformer I once used was spec'd (to the best of my memory) flat from 5Hz to 100,000 Hz. I always wondered how they did this, but I certainly heard no bandwidth limitation.

Because the signal is so tiny saturation is not an issue. I don't know for sure, but I think that these transformers have no magnetic core. Hysterisis and nonlinearity would not occur with an air core.

I used several MC preamps without a transformer, but I never heard any sonic improvement. A disappointment.

I used several MC preamps without a transformer, but I never heard any sonic improvement. A disappointment.

Surely you aren't saying "heard some so heard them all"?
( And I didn't call you shirley! ;-) )

I've heard/owned a few with xformer and tube MC stages. None approach my current active (JFET) MC stage Alaap. Not even close!