VTL ST-50 tube amplifier

inspiredsports

I'm really amazed with how things have progressed from about exactly 2 years ago today!

Every day is an experiment and I learn a little more reading here and elsewhere, and then give what I can afford a try. As some know, synergy is everything. It's astounding what vintage gear can do with a little TLC and the right mix.

I'm working to swing the M.F. CDP in the Flea Market now as I think that would put me exactly where I need to be for the foreseeable future.

george daniel

Glad it's working out for you,,I'm having my compact mono's completely re-worked/modded,,ptp wiring etc,using 6L6 power tubes,,should have em back in a couple of months.

inspiredsports

george daniel wrote: »

Glad it's working out for you,,I'm having my compact mono's completely re-worked/modded,,ptp wiring etc,using 6L6 power tubes,,should have em back in a couple of months.

Who's doing that for you, George?

I'm always interested and compiling a list cuz my MO is pretty much to find great vintage gear, and then bring it up to current year technology.

Here's my short list:

In House Stereo Repair in Setauket, NY - - - for NAD
Music Technology in Springfield. VA - - - for VTL and Conrad-Johnson
Rock Grotto in Caithness, Scotland - - - for Musical Fidelity
Stereo X Tuners in Flint, MI - - - for basically any FM Tuner

Dang, is this thing sounding sweet! I don't listen that loud, but one of my benchmarks is max spl at my listening position that is not painful. This VTL is not even close to being broken in and 90+ db is pure bliss

george daniel

Blair Lamphear of Nightshade Audio,,I recently auditioned his Beacon II preamp,6SN7 based,,his approach is "old school",tried and proven circuits that he has studied and tweaked.I had a long and interesting conversation with him about a week ago,,I sincerely believe that he is the real deal too,,especially after listening to his gear.My VTL's are sweet when dialed in,but they require alot of hands on,,so it's time for an upgrade.I don't know if there is a next level to these,but we are gonna try,,there is something special about VTL vintage gear,,hard to describe,but when those amps are "dialed in",,you hear it.Great to hear that you are enjoying yours,,it's a special piece of gear that they just don't make anymore,especially at the price point.Happy listening.

inspiredsports

Saint Patrick's Day Update:

I've been using an exceptional matched NOS quad of Telefunken ECC801S's (12AT7 equiv) in the VTL ST50 since 11/17/10. Prior to that I was using a very nice 1960 NOS quad of 1960 Amperex E180CC/7062 long plate RT's.

I felt the Telefunkens were a bit better with the highs and about the same midrange and bass.

Several months ago I picked up a couple of matched quads (a 1959 quad all measuring 100% +/- and a NOS 1962 quad all measuring 120% +/-) of Valvo Hamburg ECC81/12AT7's that I've been sitting on.

This afternoon, I installed the 1962 NOS quad and I wish I had done this months ago! They are simply astounding, and I feel in my particular system, they surpass the Telefunkens. They seem to be perfect from top to bottom and the soundstage is incredible. My wife called me for dinner 2 hours ago and I'm still down here :biggrin:

My next target is a quad of Mullard Blackburn's, but I think it is going to be very hard to unseat these VF2 code Valvo's

(a special thanks to H9 for his advice!)

tonyb

Glad to see you got your hi-fi on. Sounds like one of those pieces you take to the grave with ya. Love to get an ear on that puppy. Congrats again, and kudo's to H9 for stearing you on the tubes. He's a good dude....sometimes.:biggrin:

inspiredsports

Big Dawg wrote: »

Hey, are you using the 2Bs or the SRS2s?

To update, the SDA SRS II's are now complete and have unseated the SDA B's. I have 1 more tweak for the 2B's before a final showdown.

inspiredsports

F1nut wrote: »

For 12AT7's in David Manley designed tube amps I prefer the Mullard CV4024/M8162.

Well, it only took me 9 months to get there, but I just rolled in an extremely strong and well matched NOS quad of Mullard (Mitcham factory, Shield Logo) CV4024/M8162 tubes into the ST-50 Amp.

I'm going to let these Mullards season a bit and then rotate back through the Telefunken ECC801's and Valvo (Hamburg) ECC81's to be sure, but from what I heard today the Mullards most likely will keep the starting position.

F1nut

In the unlikely event that you do not keep the Mullards, let me know.

inspiredsports

post #41 (by SOONU111) reported as spam

inspiredsports

F1nut wrote: »

In the unlikely event that you do not keep the Mullards, let me know.

There is a chance that could now happen as the mix will change very soon :biggrin:

I've finally reached the point with component selection that I'm fine-tuning for synergy with tube selection.

The line-stage (V5, V6, V7 & V8) in my Conrad Johnson preamp sounds super with 3 NOS 1956 RCA 5751 Triple Mica Black Plates in V5,V6,V7. I have been fine tuning with 10 different NOS 5965's in V8 where a NOS 5965 Triple Mica RCA Long Gray Plate with Square D-Getter and Copper S-Rods seems to yield the best results. My next goal for the pre is to get my hands on a 5965 Telefunken for comparison in V8.

My VTL ST-50 uses 5881/6L6 power tubes and ECC81/12AT7 signal tubes. I have an exceptional NOS matched quad of 6P3S-E/6n3cE Russian PAINO IAUNA Vacuum Tubes that I got from Jim MsShane that sound best paired with matched NOS Mullard Shield Logo CV4024/M8162's. My NOS matched quads of Telefunken ECC801s's and Valvo Hamburg ECC81's are very close behind.

The upgrade bug just bit and I figured the biggest improvement might come by adding some even better top-shelf power tubes into the mix. To those I've contacted by PM, Thanks for all of your help!

They are not here yet, but I pulled the trigger . . . a matched NOS quad of RCA 6L6GC Black Plates is on the way.

As always, I feel like a little kid awaiting Christmas morning while they are en-route.

It will be fun to get them in place and go back through all of my 12AT7 quads to find the best match-up.

I'll update when the quad arrives . . . .

inspiredsports

The quad arrived this morning and I immediately warmed up my tester to see how they looked. They look identical, but 2 are coded "MF" and 2 are coded "61 09". No cathode leaks and closely grouped NOS merit readings of 122, 118, 120 and 118.

I knew re-biasing would be needed so I brought my amp to life with my Variac so I could get an idea as to whether the bias had to go up or down. Surprisingly, it was close enough that I wouldn't have had to worry, and I had the bias holding rock-steady at 285mv +/- after about 45 minutes.

Then I let the tunes begin. I have been spinning CD's and LP's for 8 hours, barely coming up for air!

Well, all I can say is that this point in time, I think RCA 6L6GC Black Plates are everything you've ever heard they were, and more. I thought the McShane tubes were good (and they are), but today has been an out of body experience!

I'm using the Mullard CV4024/M8162's in front of them now, and will rotate through the rest of my NOS quads of signal tubes as the week progresses . . .

--- Telefunken ECC801S; Short Gray Square Ribbed Plate, Triple Mica, Copper Support Rods, Halo Getter
--- Valvo ECC81, 1962 Hamburg, Short Gray Wing Plates, 2-Mica, Extra Support Rods, Halo Getter
--- Valvo ECC81, 1960 Munich, Short Gray Wing Plates, 2-Mica, Extra Support Rods, Halo Getter
--- Amperex E180CC/7062; 1960, Long Gray Box Plate, 2-Mica, Copper Support Rods, Foil Getter
--- RCA 12AT7 WA; 1961, Short Black Wing Plate, Triple Mica, Extra Support Rods, Square Getter 12AT7 WA
--- GE JAN 6414W. 1973, Thick 2-Mica, Long Black Ribbed Plate, Halo Getter

As I write, I'm listening to Mark Knopfler "Sailing To Philadelphia" as it's never sounded before. All day I've noticed the soundstage is even wider than before, but it's the depth that is most dramatically improved. The bass is both fuller and tighter, mids smoother, and highs unchanged. I'm anxious to roll the Telefunkens in a day or two as I believe their highs will augment the improved bass from the 6L6GC's.



More Later or tomorrow . . .

george daniel

Congratulations--looks like you've got some input tube rolling planned,,have fun,,I know you are enjoying it.

inspiredsports

george daniel wrote: »

Congratulations--looks like you've got some input tube rolling planned,,have fun,,I know you are enjoying it.

Yep! :biggrin:

I've used each of those quads above (plus the EH 12AT7's you sent and a cheap quad of GE 12AT7's I had) in front of the original VTL and new Sovtek 5881's you sent with it, as well as the new 6P3S-E 6L6 variants I bought from McShane.

The best prior combo was the Mullards in front of the Selected Russian 6P3S-E's.

The RCA 6L6GC's make this sound like a new amp within the same family; like I went from the ST-50 to the ST-85. It sounds as if it's much more powerful, and the bass is just night and day more solid.

It's so addictive that this week is going to be a write-off business-wise because I know all I'm going to want to do is roll tubes


Also, the mods Bill Thalmann at Music Technology performed are really shining through. I'm able to fine tune power cables with the IEC connection, and the upgraded power section and Audience Auricaps are now completely seasoned.

inspiredsports

So I'm done for a bit.

The Telefunken ECC801S's are in front of the RCA 6L6GS's in the amp and it's stellar. I'll listen for 2 weeks before going back to compare the Mullard CV4024/M8162's. They are close and my 2 top signal tube quads. The RCA's are here top stay, in fact. I'm seeking another NOS quad as they sound so good.

I've made 1 additional change in CJ PV-5 phono section; V1/V2 now sport NOS Mullard ECC83/12AX7 long gray plate 1958 F91 Blackburn's with matching codes. This is the best my vinyl has ever sounded.

heiney9

What year/style are the RCA 6L6's? I run the baby brother RCA 6V6's, gray glass, black plate, bottom "D" getter from the early 50's and absolutely LOVE them......LOVE them. My amp uses a quad and I have (2) spare quads +1.

The only 12AT7 (Ecc81) tube I've found better than the TFK ECC801S is the TFK 5965 and then it's just a matter of taste.

Good to hear your finding your favorites.

H9

P.s. I have to add the Valvo Hamburg tubes are also tied for my favorite 12at7 (Ecc81) tube.

inspiredsports

There's an image in post #42 above for a visual. They are the largest version with Black Plates, 2 D Getters at the bottom. In orange, "Made in USA", "RCA Electron Tube" and the RCA Logo are written on the dark chocolate/black micanol base. RCA above a stop sign shaped line with 6L6 above GC inside of it is etched in gray near the top of each tube.

The only identifying marks, also in orange on the base: 2 showing "MF" and 2 showing "6109".

As far as structure, all 4 look identical and measure 122, 118, 120, 118 respectively on my rebuilt Eico 667 where 80 is minimum good and 140 is the max on the scale. Most of the NOS tubes I've purchased have measured between 110 and 125 on this particular tester.

heiney9

"MF" is April 1961, not sure what the 6109 signifies. Orange writing usually indicated 60's and 70's tubes. White writing usually indicates 50's tubes......this is not set in stone but is pretty consistent.

heiney9

Greg, you like the details as much as I do so here's an RCA link I find fascinating and where I got the date information.

http://mysite.verizon.net/tubetronic/PDF_FILES/RCA%20DATE%20CODES.pdf

H9

inspiredsports

heiney9 wrote: »

Greg, you like the details as much as I do . . .

Thanks Brock! You got me there. I'm a detail FREAK :biggrin: and I like to learn as much about vintage gear as I can.

I just unplugged and studied them again for more clues with my 40x lighted loupe.

The orange lettered code actually appears with a dash in between as . . .

Made In
USA
61-09

Again, the construction is identical between the 2 bearing the 61-09 and the 2 bearing the MF codes. I just assumed the 61-09 was 1961-September.

At any rate, these are some mighty fine tubes that I would not hesitate to recommend for any 6L6/5881 application

inspiredsports

I've now moved to tweaking the mix in the modded Conrad Johnson PV-5 preamp. It seems to match extremely well with the VTL amp.

The line stage of pre uses 5751's in V5/V6/V7 and a 5965 in V8.

The phono stage uses 12AX7's in V1/V2, a 5751 in V3 and a 5965 in V4.

My favorite 5751's are NOS 1956 RCA 5751 triple mica black plates with copper support rods, my favorite 5965's are NOS gold pin Westinghouse/Sylvania triple mica gray plates with copper support rods. My latest roll put NOS 1958 F91 code Mullard Blackburn's into V1 and V2.

I'm finally at a point where I can sit back an enjoy the music (for a while :biggrin:)