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Posted by Paul Costa on
06-17-2014
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fiogf49gjkf0d Romy do you know anything about their preamp. This unit looks massive. Very little info available on it. The one description I found sounds like some of the typical American over done foolishness.
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Posted by Romy the Cat on
06-17-2014
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fiogf49gjkf0d  Paul Costa wrote: | | Romy do you know anything about their preamp. This unit looks massive. Very little info available on it. The one description I found sounds like some of the typical American over done foolishness. |
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Back in 90s there was a now extinct magazine "Ultimate Audio" that I think published a review about it. I had it somewhere and it was kind of strange reviews as I remember where the revere was fighting with some kind of imaginary wind mills and more review the company then the preamp.... I have seen and hear this Expressive Technologies Model 1 preamp in the home of the Expressive Technologies owner, I do not remember his name now, the chemical guy. I do not even remember what I was listening as to hear anything was not my objective then and I was stoking the guy with begging him to make for me his Expressive Technologies SU2 transformer. He has a listening room with that Expressive Technologies preamp that I think used 6 or 8 6SN7. The preamp was huge, super heavy and I need to report in really was not as ugly as it was on the picture. It is not photogenic preamp but seeing it I need to admit that it has own grace.
About looking massive, it was and I need to admit that pretty much anything that the guy did in his room was super massive. He had I if I remember correctly full range electrostatic that he was driving directly from plates of his amps unit absolutely enormous side transformers. I do not remember if the electrostatic were 6 feet tall of it was the transformers 6 feet tall. It was VERY ambitious.
About the typical American over done foolishness. Unlikely, I did not read the guy as somebody who care too much to build something "over done" and then sell it, he did not live from his audio income as far as I could tell, good for him. The most important why I would extend some trust to him was of course the absolutely astonishing performance of Expressive Technologies SU2 transformer that I eventually suck out from him. I am going to tell you: knowing that his SUT goes compare to anything else I have seen out there would trust to him with ANY transformer project. Well, if it would be a " transformer project" then why shall I presume that his preamp would be " typical American over done foolishness"?
The said story is that Expressive Technologies prams were in play good 15 years back and nowadays it is very hard to correlate what I fell about preamps today and what I was thinking 15 years back. If you asking then you most likely has it within your reach, and if so then I would defiantly give it a try as I feel that Expressive Technologies were very interesting firm.
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Posted by Paul Costa on
06-18-2014
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fiogf49gjkf0d I have a PDF file of the manual if it interests you to read it, I can email it to you.
The unit weighs 80lbs, uses 6 6sn7's.
What I found a little odd was the spec for the phono is it says : MM Phono Stage Gain: 64 dB at 1 kHz
I own a Expressive SU-1 and can't imagine it getting much better than that for an SUT. I am very curious about the phono in it but that spec is very unusual for MM.
I read something on line that it uses a 2kva transformer for the power supply. It says it is heavily shielded but wouldn't there be a chance of magnetic fields potentially affecting the sound?
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Posted by Romy the Cat on
06-18-2014
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fiogf49gjkf0d | Paul Costa wrote: | I have a PDF file of the manual if it interests you to read it, I can email it to you.
The unit weighs 80lbs, uses 6 6sn7's.
What I found a little odd was the spec for the phono is it says : MM Phono Stage Gain: 64 dB at 1 kHz
I own a Expressive SU-1 and can't imagine it getting much better than that for an SUT. I am very curious about the phono in it but that spec is very unusual for MM.
I read something on line that it uses a 2kva transformer for the power supply. It says it is heavily shielded but wouldn't there be a chance of magnetic fields potentially affecting the sound? |
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Thanks, for offering the manual, I really do not need it, if you want I can post it at the site but I do not think that there are a lot of people out there who would be interested, with exception that it might have a schematics, which I think it does not have.
The 6 6SN7, that is interesting choose. I do not know if they bridge those dual triode or use them in fully symmetric application, if the unit has phase switch then it might be later. The 3 stages of 6SN7 is kind of interesting chose and they are low gain tubes and usually people put in the first gain stage some kind of high gain triode (let say 12AX7 or 6SL7) and then follow with preamp-type of triodes 12AU7 or 6SN7. It is perfectly possible to make 3 stage 6SN7 RIAA preamp and I think RCA did it in past but I wonder how the hell they got 64dB gain. Each 6SN7 stage make 20dB and the RIAA network shall each 20dB, so where they got extra 4dB? I do not have an answer. Anyhow, if they do have 64 dB gain then I do not see why the spec should be odd. Do not forget that phonostage on the unit does 40dB gain and you have extra 20dB gain by preamp section - sound completely reasonable to me. In fact when I see 40-50dB gain MM phonostage I always feel that it is not enough - an MM stage shall have at least 60db gain and MC shall have 80-85dB gain - this is how I would like to have.
If you have Expressive SU1 then along with Expressive preamp you have near 90dB gain - so you are all set for any super low MC cartridge. I do not know how the Expressive preamp sound but it might be interesting to hear how Expressive people meant it to be. Expressive SU1 would not work its best with phono-correctors that have high gain fist stage. I had my 7788 based two stage and I was not impressed how my SU1 worked with them. However, the same SU1 with EAR834PT was throwing the deglitzing, dynamic range and bass that was absolutely mesmerizing. So, I might presume that when Expressive people did their preamp then knew what they are doing and I think it might be very educational to hear Expressive SU1 + Expressive preamp combination.
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Posted by Paul S on
06-18-2014
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fiogf49gjkf0d 44 dB "net" gain seems only a little odd for a MM phono amp, and it may be that "net gain" is even less in this particular circuit. In any case, I'm guessing it still accommodates their own SUT; why not?
2kVA is indeed one hell of a power supply for this application, and it would absolutely require lab-grade shielding and grounding to stay quiet in this circuit. No doubt it lives in the "other" box, but still...
Paul S
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Posted by Paul Costa on
06-18-2014
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fiogf49gjkf0d Romy
So what you are saying for MM gain 64 dB means 48 dB plus the 16 dB (spec in manual) provided by the line section of the preamp are the two gains added together?
48 dB to me is a lot more common for a MM stage. With another 28 dB on top is 76 dB.
There are no schematics in the manual.
A picture of the unit:
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Posted by Romy the Cat on
06-18-2014
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fiogf49gjkf0d
Nope, if they said that it has 64dB then it has 64dB and I have no reasons to doubt. In reality the gain stages sum 84dB and 20Db is eaten by RIAA. I do not know how they got from 3 stages of
6SN7
84dB but if they claim that they did then they did.
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