MC phono stage without transformer?

Dear Raul,

"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."

Talking too much about the emotional side of music reproduction might suggest that I like a highly colored soft "tube" sound. But thats not the case. When I changed from the high bandwith Gryphon SS gear to tube gear there was no decrease in "neutrality" (which I dont like as a notion) it was just more open, breathing and natural which surprised me as a then tube newbie as well. I think its the most common preconception on tube gear is always "warm" "colored" or whatever. That might be the case with some proportion of the tube units but it can't be said in common as well as it can't be said that a SS amp always has to sound bleached and thin. Sure due to the specific technology tube gear should be partnered with appropriate surroundings.

"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."

In general to tell from the specs on the sound is imho highly speculative. But I think you speak of the output impedance of the VAC 80/80 but this is a completely different design than the PA60...Anyway I had the Gryphon SS gear (which can control almost every speaker) and tube gear here in parallel switching back and forth any combination to convince myself since I never was a "tube guy". There was no trace of mismatch lesser control, or "unnatural" coloration. The VAC has also has a 2 Ohm tap but I prefer the 4 Ohm tap.

"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'm a musician myself and I think I would not like a too sweet or unnatural sound in the long run. But speaking of "correct" and "neutral" I have to say that I have been in a lot of regular studios(not the ultra expensive ones). From these experiences the terms "correct" and "neutral" lost a bit of significance for me in the last years. If I see how a lot or maybe the majority of music is record today, it makes me wondering how the high-end community is fixed so much on the terms of neutrality and correctnes when the software itself is not neutral or correct to the original sound.

In the end for me personally it is more important that the music through a given system appears to our senses as natural and believable than a single specification sheet. In the best case both music making capabilities and specification are top. But I've heard a lot of stuff that was sure technologically superior but it made "sound" instead of music.

Best regards

Ron

very well put Ron !

This has to be one of the best threads have read on Audiogon.

I would like to bring up a couple of related side issues for comment . . .

First, I think that a division must be made between the use of external vs. internal transformers. Obviously, the proper loading of the transformer secondary is extremely critical, and if it is an external unit . . . than I can't see how the real-world loading can be anything but indeterminate. It also seems that external units pretty much all have very high ratios . . . for i.e. 30dB gain. This makes for an inherently compromised transformer design, and additionally puts the entire chain in a sub-optimum gain structure. An interesting comparason would be to an active MC head amp . . . an arrangement that I have found quite unsatisfactory with the few that I've used and measured.

Second, a transformer simply cannot offer anywhere near the level of flexibility in cartridge loading that an active design can . . . there are certainly a great many cartridges (including all MM types of course) for which a transformer is simply unsuitable. I must say that I am greatly impressed with the thoroughness that Raul has approached this subject, and we are quite fortunate that he freely shares it on this forum.

I'm currently in the evaluation stage of a new phono preamp design, and the main topological choice was between a direct bipolar input with four MPS-A18s in parallel, and using a low-ratio Jensen JT-346 with a 990 opamp. I chose to use the transformer/990 because it was about 5dB quieter (5 ohm source), had somewhat greater headroom, and inherently blocks the input bias current - in addition to the usual transformer strengths of ground loop isolation and RFI rejection. That's not to say that the direct bipolar approach didn't have its strengths . . . bandwidth and LF linearity were of course among them. And I did have to make a decision to make the unit incompatible with many cartridges in order to use the transformer topology.

In the end, there are pitfalls with both approaches, and I'm confident that my success or failure with this will be overwhelmingly dependent on my ability to carefully optimize all the circuit and construction parameters . . . and very little to do with my "reactive component dogma".

I would posit that the Atma-sphere MP1, Raul's preamp, the Vacuum State RTP3D, and the Dolshi are all relative bargains in this era of $15,000 linestages. Don't know about the Dolshi, but the first 3 offer balanced, dual-differential circuitry (which when properly implemented inherently reduces noise) and plenty of phono gain, plus a state of the art linestage, for around $10,000. I know that's a prohibitive cost for some, but in the overall scheme of things, it's very fair. I am crazy for my MP1, but I'd love to hear the other contenders too.