A phonostage friendly 12AX7??

[hal55]

In the very near future (next Tuesday in fact - payday) I'll be ordering a Yaqin MS-22B phono stage. I want to pull the stock tubes and replace with a very much more musical tube that has a clean, liquidy top end (piano and strings are deal breakers for me) BUT I don't want something that will make surface noise more pronounced. I use Tungsol reissues in my DAC to great effect but are there others I should be considering?
After a clear but warm tube with great musicality and PRAT, that will make my TT sound gorgeous. Not after a solid state digital type sound that seems to be all the rage at the moment in cartridges and phonos. Will pay to about $20 per tube (only need 2).
Any suggestions?

Hal55

[OneyedK]

I own a Yaqin MS-22B and I can tell you this, the problem with this stage is not the tubes, it's the design.

But to answer your question, you need a tube with lots of gain, in order for the circuit to work properly.
Tube Amp Doctor has a lot of choices, depending on your budget...
http://www.tubeampdoctor.com/en/shop...m_Selected_390

[hal55]

Interesting comment, you find the yaqin lacking in gain and or drive? I was thinking of a tube along the lines of the Mullard reissues, ie

http://www.tubeampdoctor.com/en/shop...TAD_Tubes_1749

Any thoughts as to suitablilty?

I take it from other postings that when the Yaqin works well it can sound very good indeed, I'm curious what cartridge you are using that you find gain lacking?

Hal55

[Floyddroid]

Here goes, My view is that the whole tube rolling penchant is just the same as cables in that it is merely a question of tuning. I very rarely buy amplifiers with tone controls on them due to the fact that so many manufacturers get them wrong.
With regards to phono stages i have found that changing the rectifier valve makes more of a difference than the drivers. That said i would suggest you tread carefully as it could prove expensive. TJ full music valves work very well in phono stages and may well address some of your demands.
In addition to this i honestly believe that a lot of snake oil is spoken with regards to NOS valves ie Mullards etc. Many new valves are just as good if not better. Certain brands of valves are favoured for the good old fashioned snobby one upmanship that prevails in our treasured past time. I have no doubt that i will be berated by the more technically minded for my comments though i base my opinion on the very fact that i have a box full of valves of all denominations NOS and new. These are my tone controls. I bought my phono stage with JJ Teslas in it, i swapped and changed them a few times buying new ones and ended up putting the JJ's back in.
Many manufacturers have already done the work for you by placing the most suitable brand of valve in the product. Judging from what you have said i would look for a different phono stage.

[hal55]

I've had a loan of a very respected phono stage for two weeks and have simply come to the conclusion that solid state isn't for me. The Shuguang valves that the Yaqin comes with as standard are cheap as chips and, having had them also supplied in my recently acquired line preamp, they are actually not at all bad when run in. Bit gritty though at the beginning.
I do indeed use valves to tailor the sound to what I like, fitting a musical and involving tube pair will push my vinyl rig in the direction I want - something you can't do as readily with solid state where soldering and circuit reading skills are need. I'll agree 100% that in a perfet world I could afford a much better phonostage like the 2 box Avid that I heard in Sydney recently, that was lovely but sadly well outside my small budget.
The Yaqiin may or may not be a keeper, time will tell and if I don't like it it will be sold and funds put to something better when Ebay throws up a better proposition. Ebay isn't doing much of that though lately, I have been watching for well over a month now and nothing has surfaced.


Hal55

[OneyedK]

you find the yaqin lacking in gain and or drive?

I found the yaqin lacking in bandwidth, noise/hum and soundstage
I bought it because it was cheap and I hoped by modding it, it could turn out pretty great.
In the end, it's simply another Chinese copy of a bad american/european design from the 50's...

If you select a tube, select one with high gain and low microphonics.
Most tubes specified for 1st stage guitar amps are perfect.
The reason why you want all that gain is the design of the amp.
It's a 2 stage gain and one feedback loop (RIAA corrected), if the gain is too low, this amp will loose stability.

Another problem is that the second stage of the amp is grid leak biased.
This topology is very sensitive to the tube used.
So depending on the tube where it is designed for, it will start eating tubes over a relative short time period.
You can alter the grid resistor to improve things, but you have to do this every time you change a valve
--> you also "tune" the distortion signature in this spot.

btw, best bang for the buck and really low heater hum:
http://www.tubeampdoctor.com/de/shop...Electronic_456
--> I use a large number of these, servicing guitar amps, they never let me down. I think of the 50 I already used, only a few came back in half a year.
And the guys at TAD replaced them for free...

[Søren]

The stock tubes in the MS-22B are not bad at all. They are latest generation Shuguang, and they sound quite good.

I have tried a lot of tubes in it. The TAD 7025S is a great tube, but i don`t like it in Yaqin, for some reason. My preferred is the ordinary TAD 7025, which are selected JJ`s. A clean clear tube, with just a hint of warmth to it.

OT: That said, i am not too impressed with the MS-22B. It sounds nice, and is worth the money, but not much more (IMO off course).

[OneyedK]

The TAD 7025S is a great tube, but i don`t like it in Yaqin, for some reason.

Less grid leak messes up the bias of the second stage, so your ears are right...

[goraman]

Sovtek LPS has the most quoit noise floor of any new production tube and they are smooth as hell.
But if a tiny noise floor is ok the new reissue Tungsol or( Genulex Gold lion if you can afford them).

[AlexM]

I don't know the Yaqin, but I use the Sovtek 12AX7 LPS in my Conrad Johnson PV-15 phono stage, and they are very quiet - certainly less noisy than my supposedly top-notch NOS Mullard CV4004s which I'm not keen on at all in a phono preamp.

I have also used EH and Tung Sol reissue 12AX7s. Both are a little noisier and brighter sounding than the Sovtek. I conclude that the Sovtek 12AX7LPS is quite a tonally balanced, neutral and quiet valve in this application, and it is also cheap!.

Cheers,
Alex