His Master's Noise: A Thoroughly Modern Tube Phono Preamp - Page 9

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.

9th December 2010

studeb

diyAudio Member

Their web site currently lists DCR as 2 (ohms i guess ? ) and it lists 2mH for inductance.
I can check at home this evening.

9th December 2010

On Hiatus

If that's the case, it will work fine, better than it does with my 15 ohm 0.2mV Technics.

"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

9th December 2010

jackinnj

diyAudio Member

Adding a little to the lead resistor R7 does one trick. The second is to decrease R8, the 3.3K and add a few hundred pFs to C1, or at least so says the sim. Will have to wait until Friday.

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

9th December 2010

On Hiatus

Well, at this point, you're +/-0.2dB, which ain't bad. Channel to channel matching is the most important and your data looks pretty darn tight. I did things the hard way, lots of trimming, but I don't have an inverse RIAA that I have confidence (read: calibration) in. I'll probably pull the network components off my perf board to stuff in the PCBs, just to save a few steps.

"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

11th December 2010

jackinnj

diyAudio Member

Some channel to channel matching --

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

12th December 2010

Salas

diyAudio Chief Moderator

No way to bump it up a bit around 6kHz also?

12th December 2010

On Hiatus

A little trimming of C2 ought to do that.

That slight upper midrange dip is very popular in audiophile circles.

"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

12th December 2010

Salas

diyAudio Chief Moderator

Is it that the 'lost constant' resistor can be dipping it before it takes off higher?

12th December 2010

On Hiatus

Yes. It does make the sound more "high end," though.

"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

12th December 2010

jackinnj

diyAudio Member

About 0.07dB is due to the difference between the networks with and without the 3uS compensation.

the dip would make the Thors sound a little less bright.

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