Sophia meshplates vs. NOS?

[Dr. Toobz]

Though they have been mentioned here occasionally, I wanted to get some definite opinions/observations from anybody who has used the Sophia mesh-plate 2A3's in their Stereomour. For the moment, I am switching back and forth between NOS 45 tubes and NOS RCA dual-plate 2A3's, and am hypothesizing that part of why my Heresey speakers sound so thin, image-less and unimpressive in my new condo may have partly to do with these tubes being too lean or accurate for this setup. From what I understand, the Sohpia tubes are known for being somewhat lush sounding and mid-centic; would anybody who owns (or has owned) these care to chime in? I have to make a decision to either keep the RCA's or send them back per the return policy and order the Sophias....

[Mike B]

I tried Full Music mesh plate 2A3/n factory direct from China.  Ran them for about 8 hours.  That was all I could stand.

They sounded thin and weak.

Removed and replaced with EH 2A3 Gold.

[Alonzo]

I have an older pair that I love (enough to build a seperate amp just for them) I think there's been some manufacturing changes or design changes, I bought mine on recommendations and opinions that all stated how lush and full they where.  Lately everyone has been stating the tubes are thin and harsh sounding.  It might be that they need break-in, mine have hundreds of hours on them.

[braubeat]

I have Sophia meshplates I bought a few years ago for my Paramour. I like them a lot.

Michael

[howardnair]

i have sophia 2a3 meshplates-and 300b/2.5v meshplates -and i run them with heresy's
very pleased

[Jim R.]

Yes, they can be very warm and lush sounding -- I've used several types over the years but without exception they need at least 300-400 hours of break-in nowadays as they don't seem to be anywhere near fully activated when they leave the factory.  I'm planning on trying a pair of 45s soon, but bought from Sophia, not TJ.

-- Jim

[thaddeussmith]

So if I skipped the whole "tube rolling" and went straight into a Stereomour build with Sophia 45's I likely wouldn't be too disappointed? What about the stock 12AT7 tube in the kit? Would it be an ok match with the Sophia's or is there more of a preferred pairing?

Some people enjoy the act of constantly tweaking gear and the expense that goes a long with it, but I much prefer analyzing the decision to death on the internet and ultimately buying as close to a "plug and play" solution as I possibly can. I know it will come down to final system synergies, but if I can get a good starting point right out of the gate I'd certainly prefer not to waste the time and money trying other options only to end up at the same spot.

[Paul Joppa]

There are a few 12AT7 variants that get special notice. Mullard and Telefunken come to mind, though I haven't experimented myself. If you have more than enough system gain, the 5670 and its variants are good candidates, though you'd have to modify the C4S board to get adjustable bias (as in the Paramount recent revision). Also, I think the 12AY7/6072 is more or less a drop-in - nowhere near the same tube but it should work out to appropriate voltages. It has a much higher plate resistance, but with the small Miller capacitance of a 45 it ought to be OK. More of a question with a 2A3. This tube has a really good audio reputation, so don't expect to find a lot of cheap ones! GE made a 5-star version...

[Grainger49]

Paul didn't mention my version.  I put in single triode 76s as my drivers.  Now, I have Paramours, monoblocks.  But if there is enough heater current those would look super cool next to the output tubes.  They also sound pretty good too!

Poster Paully built a 76 driver 45 output amp here one weekend.  It drove my Triangle Zerius (94dBW) speakers to volumes that shook the room.

[Paul Joppa]

I don't think there is a 12-v version of the 76, nor is there a dual version. Both issues make it problematical in a Stereomour (so does the low gain). But I could have mentioned the 12SN7, for those who like that sonic. There seems to be more of a love/hate split on the *SN7's with relatively few in the middle.

Actually it would be interesting to do some experimenting. I've always used what I consider a working minimum plate current in a driver, just enough to run full voltage at 100kHz into the output Miller capacitance - that's a safety factor of 5 relative to 20kHz, which seems empirically to be past the point of diminishing returns. But there are many who believe the more driver current the better.  I wonder what a 5687 at 23mA per triode would sound like?

[Jim R.]

Thaddeus,

The problem with researching tubes on the internet is they are always impressions of individuals whose gear, power, room, and listening preferences and perceptions are likely different from yours and not easy to quantify.

That said, and in my SR-45s, I very much like the original sonics of original old stock American 45s.  I find the RCA derivatives (RCA, cunningham, national union, etc.) to be a bit warmer and fuller sounding and say the sylvanias to be a bit more "lively" if you will.  In fact I sold my EML 45 meshplates as like the originals much better, and they're a good bit cheaper (except for the 245/345 globe types, which are much harder to find in good pairs.)  I haven't finished my sterreomour and don't plan to build it as a 45 amp anyway, but my guess would be that a 1950s Raytheon triple mica black plate 12at7WA would be a nice match with either old stock American 45s or new production ones.  These tubes too will take some digging around to find, but they'll last a lifetime when you get one, and again, not nearly as expensive as the new production or NOS euro types.

So, there's my personal opinion on a starting point that certainly won't disappoint even if it's not your final stopping place.  You could spend a whole lot more and not do as well, that's for sure.

Yup, system and room synergy, and ultimately what floats your boat.  Who knows, the sophias and stock driver tube may be what you ultimately find best to your ears.

Sorry if this is a rather vague recommendation, but that's about all anybody can honestly give you.

Jim

[thaddeussmith]

Oh i totally understand. Sometimes, however, you can ask a question such as I did and receive an overwhelming majority in a certain opinion. Probably won't be the case here, but you guys have already given me new brands and alphanumeric things with which to google.

[Paul Birkeland]

Actually it would be interesting to do some experimenting. I've always used what I consider a working minimum plate current in a driver, just enough to run full voltage at 100kHz into the output Miller capacitance - that's a safety factor of 5 relative to 20kHz, which seems empirically to be past the point of diminishing returns. But there are many who believe the more driver current the better.  I wonder what a 5687 at 23mA per triode would sound like?

I wonder if the BeePre C4S board could be stuffed into a Steremour for said comparison, though it doesn't leave any room for the TL431 to bias it up.

[Paul Joppa]

300 ohm cathode resistor, no bypass.  :^)

At that much current, the increased source impedance of an unbypassed cathode resistor still gives plenty of drive for the Miller capacitance - corner above 200kHz by my calculation.

The low gain will be a concern of course.

[drewh1]

I haven't change the 2a3'S but had nice results with a NOS Telefunken 12at7. much less expensive to try and very noticeable change in warmth and clarity.