Step-Up Transformers v Phono Preamps

[MartinT]

but Martin, why persist with high speed op-amps and shed loads of negative feedback when you could use a valve like FET with little feedback and passive equalisation?

Dave, it was really a question of circumstance that allowed me to hear the GCPH in action and subsequently order the Underwood modded version. I did look at the A.N.T. brochures you gave me and my interest was piqued but I never got around to talking to you further about it.

To answer your question, and knowing that you dislike it, the GCPH makes fine music with both my DL-160 and the AT33PTG currently in use. I have never heard better LP replay in my system, and that is what counts.

HOWEVER, I would like to give the appropriate A.N.T. model a try as it represents an unexplored avenue and I'm happy to move equipment on to fund new components. Would a loan be on the cards?

[Dave Cawley]

the GCPH makes fine music with both my DL-160 and the AT33PTG currently in use. I have never heard better LP replay in my system, and that is what counts.

OK, no problem, but why did you order the transformer? And which one?

Regards

Dave

[Marco]

Why not, for a laugh, dig out your old Croft preamp, connect it to your system, and try the Cinemag/AT33PTG in conjunction with the Croft's valve MM stage?

Any thoughts on this, Martin? I'd love to know what would happen

Out of curiosity, when was the last time you listened to the Croft?

Marco.

[MartinT]

OK, no problem, but why did you order the transformer? And which one?

The CineMags are type 3440-A.

I ordered the SUT so that I could experiment with it, to see if it would give me even better sound quality by reducing the GCPH's overall gain.

[MartinT]

Any thoughts on this, Martin? I'd love to know what would happen

Out of curiosity, when was the last time you listened to the Croft?

Marco.

I am thinking about it. I haven't listened to the Croft SIP in many years, not even sure if it will still fire up ok. I do remember it having a fine MM phono stage.

I did more recently fire up the Croft Series 4S power amp and that has a dead channel. Haven't got time for it really and should sell it as a project to a Croft enthusiast. Too much equipment!

[Marco]

I am thinking about it. I haven't listened to the Croft SIP in many years, not even sure if it will still fire up ok. I do remember it having a fine MM phono stage.

Please do it and report back. I think you'd find the results very interesting indeed

Overall, it'll probably be worse than your current set-up (because of the loading), but it should give you an inkling of the potential of high quality valve MM stages used with SUTs, and perhaps whet your appetite enough to explore this avenue further in future...

As an aside, I reckon a Puresound P10 (with the right SUT) would work fab in your system!

Marco.

[NRG]

The CineMags are type 3440-A.

I ordered the SUT so that I could experiment with it, to see if it would give me even better sound quality by reducing the GCPH's overall gain.

The 3440A looks more suited to the DL103 with is higher o/p impedance of 40R.

http://cinemag.biz/mic_input/CMQEE-3...oving-Coil.pdf

The reflected ratio your cart is seeing at 1:10 is 47000 / (10*10) = 470R

At 1:16 it will be 47000 / (16*16) = 184R (approx)

This is closer to what the cart needs but the gain maybe too high now for the phono input.

What you need to do IMHO is add a resistor in the R1 position as indicated in the pdf link above.

A 15K res in R1 position will be in parallel with the 47K of the phono preamp bringing the total R down to approx 11.4K...

At 1:10 the cart will see a load of 114R, just in the ball park....or for R1 you could use an 18K resistor bringing the combined R down to 13K meaning a reflected load of 130R....

Fun things SUT's....

[jonners]

I was about to post something very similar to the above but Neal beat me to it. You really can't write off these transformers until you have sorted the impedances - as shown in Neal's link.

[MartinT]

Many thanks, Neal. More experimentation required. I shall order some high quality resistors.

[Marco]

Excellent stuff, chaps - that's why we have 'techies' on this forum, too!

Whatever you do though, when you think the SUT has been optimised, try it with the Croft. I'm determined for you to hear what the results are through a valve MM stage!

Marco.