His Master's Noise: A Thoroughly Modern Tube Phono Preamp - Page 28

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.

11th November 2016

jackinnj

diyAudio Member

Le voila

HMN_A.jpg

HMN_B.jpg

Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?

11th November 2016

cogeniac

diyAudio Member

Nice!!

Looks like you laid out the board slightly differently than me, but used the same partitioning (amp and CCSs on one board, power supplies on another). Is the power stuff on the bottom side of the chassis? Do you have the raw supply in a separate box?

11th November 2016

jackinnj

diyAudio Member

I would redo the boards -- with each channel on a separate pcb:

HMN_2016.png

Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?

11th November 2016

cogeniac

diyAudio Member

Why is that? Channel separation, or having exactly the same arrangement of parts?

12th November 2016

jackinnj

diyAudio Member

Less expensive. Less clumsy organization of DMosfet heat sinks.

Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?

12th November 2016

jackinnj

diyAudio Member

I just went over a couple dozen reviews of phono-preamps in Stereophile. The best which JA had reviewed (Boulder 1008, $12k) MC section had THD+N% of 0.065% The HMN is about 0.02% JA mentioned that the Boulder had overload margin (1% THD) of 33dB relative to 5mV for the MM section. Bit of an apples to oranges comparison, but the HMN isn't even perspiring at +33dB relative to 500uV (considering that it is designed for MC carts.) JA doesn't provide an overload margin for the Boulder's MC section.

In fairness, the Boulder is quieter than the HMN.

Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?

18th November 2016

cogeniac

diyAudio Member

One wonders if $ per nV/root-Hz is equivalent. At about $600 for the HMN preamp vs $12K for the Boulder.. I suspect not!!

18th November 2016

cogeniac

diyAudio Member

This may be heresy, but if one uses a MM cartridge with a higher output level, do you need the transformer? Could you just wire the cartridge in a balanced circuit to the system without the 10:1 Sowter transformers?

18th November 2016

jackinnj

diyAudio Member

@cogeniac -- about the middle of the article it was mentioned that you could dispense with the trafo at the disadvantage of having an imbalanced input. You could always use a 1:1 trafo but remember to load the cartridge with ~47k for most MM's

Why, silly hare, are you fleeing from the fierce jaws of the lion now grown tame?

18th November 2016

cogeniac

diyAudio Member

Ahh. Thanks ! I'll go back and re-read...Don;t currently have the budget for a $6K cartridge!!