VTL ST-50 tube amplifier

inspiredsports

The tubes George supplied (http://www.polkaudio.com/forums/showthread.php?t=102783) when I purchased this beauty were very good, but being unable to resist myself, I've re-tubed after 7 days.

That may not sound like enough time, but was 70+ hours with 3 preamps, 2 sets of speakers, and several CD and vinyl inputs.

George recommended Jim McShane at http://pages.prodigy.net/jimmcshane for power tubes (brand new 6P3S-E / [6n3cE Cyrillic alphabet] Paino Iauna Russian) that are rumored to be some of the very best in the 6L6/5881 family (and for only about $15 each). I also had an idea for the 12AT7's knowing Jon (doctorcilantro) had some kickass October 1960 NOS Amperex 7062 foil d-getter's in stock.

Long story short, all 8 are in place, biased,and have been hot for an hour.

I have a feeling this is going to be one of those nights where I start at one end of my LP/CD collection and don't come up for air until I either pass out or play it all the way through

The pureness of this particular mix is simply stunning.

Big Dawg

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

inspiredsports

I've listened to both and the VTL 50 tube wpc has absolutely no problem driving the SDA SRS 2's. The 2's are ultimately my "go to" speakers, but I've just taken them apart to perform a minor tweak so the 2B's are going to get all of the attention for a couple of weeks.

tonyb

Congrats on the amp. I hope you realize you stole that baby. That quality at that price ? Dude, your the man. Enjoy.

heiney9

Try the 50's RCA black plate, gray glass 6L6. They aren't cheap. I have a pair of 1968 Valvo Hamburg 6201 (industrial 12AT7) gold pin's. Absolutely the best 12AT7 (next to the Telefunken ECC801S) made.

I have 3 pairs and I only need 1 pr and 1 backup. If you might be interested PM me. I have similar early 60's Amperex BB's from all 3 plants (Heerlen, Blackburn and Lucernes) the Valvo's sound better to me.

I'll make you a good deal on the Valvo 6201's if you are at all interested. Not trying to take away from Jon's sale if that's a done deal. I have just been so very impressed with Valvo Hamburg tubes.

H9

george daniel

he, he,, moved up a few rows eh?.;)

zingo

Congrats on the nice amp and successful tube rolling!

doctorcilantro

Those 6L6 types sound interesting Greg. Sorry two of them are mp; I'll get two more out to you asap. I'll try yours in my new preamp and see as some are mp only in certain circuits.


..... and I wouldn't mind trying some 6201s Heiney, but I would need two matched pairs or quad. These 1960 foil D-getters sound incredible and I think I'll roll in some RCA 12AT7s first so I can finally hear this sound stage y'all are talking about when I roll in the 7062.

I meant to ask too, are you getting any feedback at high SPLs, with the bass hitting, or just when tapping the tubes? Just curious.

inspiredsports

tonyb wrote: »

Congrats on the amp. I hope you realize you stole that baby. That quality at that price ? Dude, your the man. Enjoy.

No, George is the man

inspiredsports

doctorcilantro wrote: »

Those 6L6 types sound interesting Greg. Sorry two of them are mp; I'll get two more out to you asap. I'll try yours in my new preamp and see as some are mp only in certain circuits.


..... and I wouldn't mind trying some 6201s Heiney, but I would need two matched pairs or quad. These 1960 foil D-getters sound incredible and I think I'll roll in some RCA 12AT7s first so I can finally hear this sound stage y'all are talking about when I roll in the 7062.

I meant to ask too, are you getting any feedback at high SPLs, with the bass hitting, or just when tapping the tubes? Just curious.

I did not notice any degradation while listening, just doing the gentle tap test with a pencil. Also, I generally use Herbie's tube dampers and have more on order as all are on the CJ pre now.

I wonder if the dampers will cure the problem?

inspiredsports

george daniel wrote: »

he, he,, moved up a few rows eh?.;)

I know a bit about diminishing returns, and this thing is so sweet I'm afraid the next .005% is going to be way expensive

F1nut

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

RuSsMaN

F1nut wrote: »

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

Nice tube, with the rep to boot.

george daniel

inspiredsports wrote: »

I know a bit about diminishing returns, and this thing is so sweet I'm afraid the next .005% is going to be way expensive

I am sincerely happy that you are enjoying it.It's a fun little amp isn't it.I nicknamed it "happy"

inspiredsports

F1nut wrote: »

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

I have a couple of those exact tubes with my PV-7, but would need to rustle up a couple more to fill all 4 spots in the VTL.

inspiredsports

heiney9 wrote: »

Try the 50's RCA black plate, gray glass 6L6. They aren't cheap. I have a pair of 1968 Valvo Hamburg 6201 (industrial 12AT7) gold pin's. Absolutely the best 12AT7 (next to the Telefunken ECC801S) made.

I have 3 pairs and I only need 1 pr and 1 backup. If you might be interested PM me. I have similar early 60's Amperex BB's from all 3 plants (Heerlen, Blackburn and Lucernes) the Valvo's sound better to me.

I'll make you a good deal on the Valvo 6201's if you are at all interested. Not trying to take away from Jon's sale if that's a done deal. I have just been so very impressed with Valvo Hamburg tubes.

H9

Thanks H9.

I'll keep my eyes open for these. It needs a matched quad or at least 2 matched pairs.

Greg

inspiredsports

I talked to Bea at VTL today (1-909-627-5944) per everyone's suggestions here at CP to see if there might be any literature available on the Stereo 50.

She had handwritten notes, only and said there was very little official written documentation even when the amp was brand new, and owner's manuals were rare. Evidently, even variations based upon serial number (this one is 5050139) were not recorded at VTL, of if they were they were not computerized and were lost. Bea did say that the fact the one I bought from George has bias adjustment pots and uses 6L6/5881 power tubes indicates it is one of the newest versions of the 5050.

My primary reason for wanting an owner's manual was to determine the amplifier's input impedance because my Shotgun 2 IC's have an adjustable impedance setting. Bea said her handwritten notes show the inputs to be 100kOhms.

inspiredsports

Well, we're back from vacation (http://www.polkaudio.com/forums/showthread.php?t=105179&highlight=wilmington) and I'm ready to get rolling.

The October 1960 NOS Amperex 7062 foil d-getter's are wrapped in new Herbies Ti-9 Ultrasonic Tube Dampers and sounding mighty sweet. My next task is to audition more tubes.

I only have a pair of the Mullard CV4024/M8162 from the PV-7 and definitely want to get my hands on 4 to try them out. I also want to try the 1968 Valvo Hamburg 6201 gold pin's and Telefunken ECC801S's.

But . . . the ST-50 needs a doctor.

I noticed a very slight hum. It went away, but about an hour in the amp just lost power. The switch is on, but the red LED is dark. I unplugged and walked away for an hour. I plugged it back in and it powered up normally, but after about a half hour the amp quietly powered down again. No noise, no odor, just fade to black. (Yes, I checked AC connections/fuse.)

I've read some of the big caps in these older models are prone to age related failure, and there can be simple cold solder and power supply issues with these units.

I use In House Service Company in Setauket NY (http://www.stereorepair.net/) for my NAD gear and have sent Conrad Johnson components both to Conrad Johnson and Music Technology in Springfield, VA (http://musictechnology.com).

They both do VTL repairs and upgrades, but I'm wondering if there is a VTL specialist some of you guys have used before?

heiney9

inspiredsports wrote: »

and definitely want to get my hands on 4 to try them out. I also want to try the 1968 Valvo Hamburg 6201 gold pin's and Telefunken ECC801S's.

Yep, I have a pair of each and they are every bit as good as all the hype. I have a pair of Valvo Hamburg 6201's I'm offering to another Polkie (I have 3 pairs and don't need them all) if he decline's I'll shoot you a PM.

H9

inspiredsports

heiney9 wrote: »

Yep, I have a pair of each and they are every bit as good as all the hype. I have a pair of Valvo Hamburg 6201's I'm offering to another Polkie (I have 3 pairs and don't need them all) if he decline's I'll shoot you a PM.

H9

Super! 2 Pairs will do the trick for me if they become available. I wanted to PM when you posted in July, but Jon beat me to it.

But, no rush now that I need to find a VTL doctor.

doctorcilantro

Heck, I was tempted to ask for those 6201s. Sorry to hear about the amp troubles.

inspiredsports

doctorcilantro wrote: »

Heck, I was tempted to ask for those 6201s. Sorry to hear about the amp troubles.

It's actually a good thing. I am always itching to send gear out for upgrades, and his forces my hand

inspiredsports

I want to make sure everyone understands I am not upset other than I won't have the best sound possible for a couple of weeks and wish I hadn't used the frown face in my post #20.

This is just one of those things that happens with vintage gear and this piece was absolutely as advertised and packed as well as I have seen when it arrived. It sounds absolutely fantastic, but just has a component that quietly shuts down when it heats up for an hour. It will be an easy fix.

I've been in contact with my guy (Wayne) at In House Service Co. and learned they are very, very good with VTL, plus Wayne owes me a favor and will price me right - http://www.angelfire.com/art2/stereo...117/manley.htm.

One huge item on my wish list for this unit is an IEC outlet on back so I can experiment with my ever-growing collection of power cables and I was already researching and thinking of sending it out for upgrades so this is not a bad thing.

george daniel

Bummer,, I know how disappointed I would be if it were mine,,I'm just that way-- hope it's a quick and easy fix.

inspiredsports

A great suggestion was made that I go back to the "known good" tubes that came with the amp when I purchased it before assuming a problem with the circuitry. I just swapped them out and re-biased, but the power faded off just a few seconds after I was done. It was worth a try, but not the cause.

inspiredsports

george daniel wrote: »

Bummer,, I know how disappointed I would be if it were mine,,I'm just that way-- hope it's a quick and easy fix.

But remember, I have my freshly rebuilt NAD 7600 receiver and 1700/2600A preamp/tuner/amp combos just jealously sitting there as the VTL has recently had all of my attention. The 7600 was happy to be put back into the loop .

inspiredsports

Good news. Wayne just wrote back that he is highly familiar with the ST-50 and this is a known and very common issue.

His diagnosis; "The High Voltage "half" of the power switch is burned out."

They have an upgraded switch available and I think I am going to send it out to him to upgrade the switch, add an IEC outlet, upgrade with AudioCap Theta tin/polypropylene caps and add polypropylene bypass caps to the cathode and power supply circuits.

george daniel

inspiredsports wrote: »

Good news. Wayne just wrote back that he is highly familiar with the ST-50 and this is a known and very common issue.

His diagnosis; "The High Voltage "half" of the power switch is burned out."

They have an upgraded switch available and I think I am going to send it out to him to upgrade the switch, add an IEC outlet, upgrade with AudioCap Theta tin/polypropylene caps and add polypropylene bypass caps to the cathode and power supply circuits.

That is good news. Thanks for the update.

inspiredsports

So, the metamorphosis is complete (with a little help from my friends) !!

1 - VTL ST-50 from George D.

1 - Complete upgrade by Bill Thalmann at Music Technology
-- All new Auricaps (19) in output and elsewhere
-- 3 rectifiers replaced with Stealth diodes
-- New power switch
-- Binding Post Cardas Rhodium, Cardas RCA's
-- Cardas IEC Female to allow for power cable swapping

1 - MIT Shotgun S1 Power Cord (from cryoed PS Audio Power Port Premier / APC H10)

4 - New (Jim McShane matched) 6P3S-E/6n3cE PAINO IAUNA Power tubes
4 - NOS Telefunken ECC801S !!! (Thanks, doctorcilantro)
4 - Herbies Ultrasonic Ti-9 tube dampers on the Telefunkens

2 - MIT Shotgun S2 IC's (to Conrad Johnson PV-5 pre that was upgraded exactly the same by Thalmann at M.T., also with Shotgun S1 power cord (Thanks, Vr3MxStyler2k3) from APC H10 to IEC)

2 - MIT Shotgun 2 Speaker Interface Cables to 1987 SDA 2B TL's with Dynamat, TFLF Rings, Cardas, Custom SDA Interconnect (thanks to dozens of Polkies too numerous to name for upgrade help).

This thing has only been hot and biased for 2 hours, and it's making the hair on the back of my neck stand up.

thsmith

Sounds like you have the right things inplace. Congrats and enjoy.

tonyb

Nice upgrades, must sound sweet. Enjoy.