His Master's Noise: A Thoroughly Modern Tube Phono Preamp - Page 29

21st April 2010, 12:00 PM
SY On Hiatus Join Date: Oct 2002 Location: Chicagoland	His Master's Noise: A Thoroughly Modern Tube Phono Preamp After more than 25 years of faithful service, it seemed that it might be time to redo my phono system. After all, I like to think that I've picked up a few tricks in the intervening years... The old system consisted of a VPI HW17-II, a Linn Ittok LVII tonearm, and a Troika cartridge. The Troika was... Click here to read the entire article Last edited by Variac; 2nd April 2011 at 12:17 AM.

18th November 2016

cogeniac

diyAudio Member

Looks like another approach might be to just use a 1:1 transformer to preserve the balanced nature of the input (and provide for a future change to a MC setup...

How do I deal with the relative input impedances?

The Jensen line input 1:1 transformers have 10K:10K impedance ratios. If I need 47K would I put two 18.5K resistors in each input leg, and 10K (or 47K?) across the outputs?

18th November 2016

lehmanhill

diyAudio Member

@ congeniac

Your other alternative is the Equal Opportunity MM pre-amp that SY designed. Fully balanced and proper impedance. It uses many of the same design ideas as the HMN, but designed from the start for MM. Naturally, no transformer.:-)

Jac

19th November 2016

cogeniac

diyAudio Member

Yeah, that look alike a better alternative. I'll explore that.

19th November 2016

peafarmer

diyAudio Member

I realize this is not a cartridge thread, but what is wrong with an Denon DL-103 MC (0.3mV, $229) cartridge. This is what I was intending to drive this preamp with. I would think this preamp would make any cartridge sound good....am I missing something?

19th November 2016

cogeniac

diyAudio Member

My concern is really the range of choices.

This may not be a perfect rationale, but the price range for MC cartridges has an average around $2K, which means at $200, you are looking at the bottom end of the offerings in that technology. MCs are hard to make, and harder to make well, which is why the average price is so high. In contrast, MM and MI cartridges are much easier, and so the midpoint of that technology is around $500. Some purists will probably argue that you get what you pay for, and nothing beats a $5K MC cartridge..but...

If you find that you don't really like the Denon, or other bottom end MC offerings, then your options are to sell your car and buy a MC cartridge made by a Japanese National Treasure artisan (preferably with a housing made from ancient cedar trees that were blessed by a Shinto priest), or build a different preamp. I am not knocking MCs, but personally, I'd rather have as many options as possible within the constraints of my budget.

My 2 cents..

If you, or anyone else want the Eagle CAD (schematic and board layout) files for the HMN (with untested board layouts) I'll be happy to post them.

I am intrigued by the EO preamp. When I was wondering how I might tweak the HMN design for a MM application realized that a differential input would probably be a good approach, But Stuart seems to have taken that to an entirely different level!

Scott

19th November 2016

peafarmer

diyAudio Member

Thanks, Scott. I would like to have the CAD drawings. I'll send you a P.M. with my email so that you can either email them to me or post, whichever is most appropriate.
Andy

19th November 2016

cogeniac

diyAudio Member

Do you have EAGLE? It is a schematic capture and PCB layout editor. I'll email the files. I think there is a free version, but the board size is limited.

19th November 2016

6L6

diyAudio Moderator

The DL-103 is a very competent cartridge, price be hanged. MC carts have turned into high-end jewelry with price tags to match.

Things to know about the DL-103 -

1) It's very high compliance, I.E., the suspension is pretty hard. It's made for heavier arms, so if you've got a lightweight it's not going to match well. Many arms have the ability to add weight to the head and the counterweight, that's a perfectly good solution.

2) It has a fairly high (for a MC) coil impedance, meaning you need to have an input transformer that will load it properly. I had Jack Elliano of Electra-Print make me a set for 40ohm and about 1:30, I'd need to look exactly. Not particularly expensive and it works perfectly.

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19th November 2016

billshurv

diyAudio Member

Don't you mean low compliance?

19th November 2016

6L6

diyAudio Moderator

Probably? I never remember, other than it's the one that needs some mass to push against. Not going to work well with a Mayware Black Widow...