His Master's Noise: A Thoroughly Modern Tube Phono Preamp - Page 25

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.

15th May 2016

anystereo

diyAudio Member

Sy,

So the basic approach would be to set up an attenuator circuit ala your figure 2, but can't I get petty close by comparing the datasheets of softer and lundahl? i am not sure how to adjust the 6k8 resistor, by comparing the two, any suggestions?

After thinking about it a bit, I think i get the floating balanced input from the tonearm, I have a nice old denon 103, but would like to accommodate a denon 103r as well or even better.

I am in, if someone wants to have some boards made, including Sy's regulators would be my preference.

The 21' maida's seem like really nice but maybe a bit too much for my budget, anyway I could go either way, with or w/out the regs on the board. I will probably build a tubed rectifier HV supply since i already have the parts.

Instead of over spending on the regs I'd like to consider spending too much on an LCR passive network, has anyone tried this the tango/hashimoto's for example? wouldn't there be a some objective advantages maybe, greater accuracy? I guess i not sure about the functioning of R1 in the eq circuit.

15th May 2016

On Hiatus

The data sheet will not get you far. Adjusting it properly isn't very hard and only takes a generator and scope, from start to finish, just a few minutes. Make sure you either use a 10x probe or if you use a 1x, take its capacitance into account. You can use a potentiometer to stand in for the fixed resistor to determine optimum value. There's a really nice treatment of this on Sowter's 8055 web page.

I'm used a modified 103R with this preamp and got excellent results. The 103 is harder to get to play nicely with step up transformers.

Like I said, the regulators aren't critical, you can go either way, whatever's easier.

There is absolutely no engineering advantage to using LCR instead of plain old RC. Spend the money on music.

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

8th June 2016

Martinljn

diyAudio Member

I am also in, if someone wants to have some boards made, including Sy's regulators would also be my preference.

10th July 2016

cucuclock

diyAudio Member

I'm in too!!!!

14th July 2016

watterskid

diyAudio Member

Interested in PCBs if you get them made

29th July 2016

dhsettim

diyAudio Member

SY said:

"In light of Merlin Blencowe's excellent JAES paper on tube noise, I'll be lowering the plate currents of the first and second stages. It won't change the performance significantly, but it will reduce heat and probably extend tube life."

I'm just getting back to completing Jack's boards after a long (long) hiatus so are there any suggestions to new lower current operating points for the first and second stages that I can incorporate at this belated building stage?

Thanks
tim

PS Thank you Jack for the PCBs

29th July 2016

On Hiatus

I'd run the first stage at 10mA, the second two at 4mA. The original values work fine, but dropping the current will extend tube life and reduce heat at no performance penalty.

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

31st July 2016

dhsettim

diyAudio Member

Thank you SY,
I'll work out a couple of new operating points at those currents and run them passed you, if that is ok.
I guess the lower plate currents will increase the anode impedance a little so a reverse riaa will likely become more important.
best regards
tim

18th August 2016

Brinkman

diyAudio Member

Just an update, Sowter has ceased production of the 8055 step-up transformer and replaced it with the 1480. The data sheet is here:Sowter Type 1480 Studio cartridge transformer

Note that with this new model, the winding resistance has dropped on both the primary and secondary. It is now spec'd at .29 and 60 Ohms, respectively vs the .72 & 102 Ohms of the 8055 model.

21st August 2016

luvdunhill

diyAudio Member

SY:

I need 15 feet of XLR cable between output of HMN and input of Impasse Preamp. Choices are:

1. Mogami 2534

https://www.mogamicable.com/category/...crophone/quad/

2. Belden 1800F (low capacitance)

https://www.belden.com/techdatas/metric/1800F.pdf

3. Canare L-4e6s "star quad" (higher capacitance, higher noise rejection)

https://www.canare.com/ProductItemDis...oductItemID=53

4. Other?

What should I be looking for when choosing a cable?

For Sale: Yet-Another-FirstWatt-PSU | "CSX1/2" "Buffered F6" FE