6550 Tungsols anyone?

heh-heh-heh...:), posted on October 29, 2009 at 10:25:35
PakProtector Audiophile Posts: 9953 Joined: May 14, 2002	Got about half that many GEC Gold Monarch KT88...:) all that test as new too. cheers, Douglas Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

RE: heh-heh-heh...:), posted on October 29, 2009 at 11:26:21
Michael Samra Dealer Posts: 13134 Location: saginaw michigan Joined: January 30, 2005 Contributor Since: June 24, 2005	Kewl Douglas I need to get a couple from you to finish my other quad set up and then I will have two quads. These sound like the ones Ross had. If the power supply waveform isn't pretty,neither is the sound in most cases.

RE: heh-heh-heh...:), posted on October 29, 2009 at 14:28:33
PakProtector Audiophile Posts: 9953 Joined: May 14, 2002	hey Mike, Give me a call sometime, it would be great to hear from you...:) cheers, Douglas Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

RE: 6550 Tungsols anyone?, posted on October 29, 2009 at 04:30:14

Michael Samra
Dealer

Posts: 13134
Location: saginaw michigan
Joined: January 30, 2005
Contributor
Since: June 24, 2005

These aren't mine but it looks like my collection of TS some what..I have 165 of them and 78 are black plates and and the rest are 3 holers and solid gray plates. They all sound great but the BPs are my babies.I only have about NOS/NIB quads of Black plates and two quads of solid gray plates and the rest are used and test medium to good. Only about 14 of my 3 holers don't make rated power.
If the power supply waveform isn't pretty,neither is the sound in most cases.

RE: 6550 Tungsols anyone?, posted on October 29, 2009 at 12:57:20
FenderLover Audiophile Posts: 3313 Joined: July 31, 2007 Contributor Since: May 17, 2009	Darn. Was going to ask you for a sextet of BP's. Mike, you have good luck with the TS 5881? I can get them to sound pretty good in older Bassman. But, they just don't sound that great in the '59 Reissued Bassman. Think that the tubes are more sensitive to the iron used, than other 6L6-types. What's your experience?

RE: 6550 Tungsols anyone?, posted on October 29, 2009 at 16:13:27

Michael Samra
Dealer

Posts: 13134
Location: saginaw michigan
Joined: January 30, 2005
Contributor
Since: June 24, 2005

Steve
You know what the funny thing about that is? I used to despise the 5881 tubes and you told me to try them in different topologies and now I like them but as you say,it depends on the iron or circuit. I always thought of them as being industrious and tough.
With the 6n3ce being so good,its hard to justify any other than maybe a kt66 or EL37..I think the 6n3ce sounds as good or better than my black plates..Of course in guitar,it may be a different scenario entirely.
If the power supply waveform isn't pretty,neither is the sound in most cases.

RE: 5881 Tungsols, posted on October 31, 2009 at 03:45:56

FenderLover
Audiophile

Posts: 3313
Joined: July 31, 2007
Contributor
Since: May 17, 2009

One of the first amps I worked on was an original tweed Bassman that had TS 5881 driven with BP RCA 12AY7's. What a great tone! I think that the TS were original or the second set. The getter rings were all worn out. Only a sliver stuck out where the rings once resided. Still could beat the crap outta that amp and it responded. Seems that the TS 5881 LOVE abuse. Crank the amp to full blast and physically beat the heck out of the tubes and the amp kept asking for more.

Would love to have one of those original tweeds with 15-inch Alnicos and the oversized output tranny. Very Bluesy. BB King tone.

I agree, on the other hand..., posted on October 29, 2009 at 03:15:52

Frihed89
Audiophile

Posts: 8445
Location: Copenhagen
Joined: March 21, 2005

I meant I agree with XLR......the quad I bought did not last long for just that reason.

On the other hand......I have not any trouble with GE6500As in that regard. They seem to be built like tanks and hold bias forever, as well as sounding better than any current production tube. They are getting pricey, though. The price has doubled in three years.
"What did the Romans ever do for us?"

RE: 6550 Tungsols anyone?, posted on October 29, 2009 at 02:34:31
audiohfil	How do I get an octet? And How Much?

RE: 6550 Tungsols anyone?, posted on October 29, 2009 at 01:51:02
FenderLover Audiophile Posts: 3313 Joined: July 31, 2007 Contributor Since: May 17, 2009	Quite a bottle collection there. Sad, they don't make 'em like that anymore. Even sadder that companies like Tung-sol are OOB.

Have they been tested for drool?, posted on October 28, 2009 at 22:44:38

XLR8OR
Audiophile

Posts: 311
Location: Sydney
Joined: August 30, 2005

Seriously, all the ones I have purchased so far have shown up very bad grid leakage problems. I don't think these vintage 6550's are worth purchasing no more. They cost a fortune and are a ticking time bomb. Had one very bad experience with thermal runaway on one tube damaging a brand spanking new ARC power amp and burning out not only the resistor but the trace-board as well.

If these are NOS and tested fully for no signs of grid leakage, I would be very interested in grabbing a quad.

RE: Have they been tested for drool?, posted on October 29, 2009 at 08:12:08

tvr2500m
Audiophile

Posts: 1380
Location: Boston
Joined: February 2, 2003

This is my experience with the TS 6550. I have mostly 3-holes types, mixed in with a few smooth gray plates. After buying my first quads, either "new" or used, they were goin' thermal all over the place! Danged!

Before inserting them into gear, I'd tested them on a battery of testers - a Hickok RD-1575, Hickok 6000A, B&K 747, TV-7D/U, Sencore MU-150, and a Heathkit TT-1. Two of these tube testers I found have really sensitive grid current draw tests, the Sencore MU-150 and the Heathkit. A tube showing just about any grid current draw on either of these two testers would likely go thermal when at full operating settings in an amp. Sometimes the condition was so bad that the tube couldn't be brought up to full bias without going thermal, sometimes it would operate for a while before running away.

I also observed that the tubes behaved differently in different amps, where the operating parameters were different. Amp running the tubes more "conservatively" were less likely to see a thermal runaway even in one or more of the output tubes.

I haven't tried the oven method, but I did come across someone who seemed to be familiar with this. He can do something like what you describe - "running these tubes for several hours using a grid voltage derived from a well regulated very low impedance source and watching the grid current reduce with time." - using a big ole Weston 686 tube analyzer, which allows independent control of all of the test settings. He did exactly that - measured the grid current draw over time - and I got back tubes with little to no grid draw.

I sent him about 50 tubes. He was able to "save" all but a couple of them, either eliminating indication of grid draw completely, or bringing it very close to zero. I've tried all in-circuit and have had no problems yet. I don't use these tubes very often 'cuz they haven't been among my favorites. I hope that this time of unuse doesn't put me back into the cycle of needing to treat them again! ;(

- SJ

RE: Have they been tested for drool?, posted on October 29, 2009 at 05:50:16

kentaja
Manufacturer

Posts: 3116
Joined: March 26, 2001

I have talked to ARC several times over the last decade about real Tung-Sol 6550 in my ARC tube amps. They have recommended against using them.

About 15 years ago I purchased output tubes from a well-known and reputable tube dealer. The output tubes destroyed my amps. So they went to Minneapolis for repair. ARC told me to avoid the tubes in question, Chinese made. If I had talked to ARC first I would not have purchased the particular tubes and would not have paid a rather expensive repair bill to fix the amps.

It never hurts to call Leonard or Chris and talk to them about tubes before you insert them into the amps. They both are more than happy to talk with people and a short phone call can avoid a lot of headaches. Neither one of them are anti-NOS in fact Chris has encouraged me many times to experiment with various tubes. But they have far more experience than any tube dealer or end-user as to what will potentially cause problems in their gear.

Naturally being curious and because I have several quads of vintage Tung-Sol, I tried them for short periods in my amps. Very nice tubes. But not enough better than current production IMO to warrant the cost or the potential damage to the amps. Lots of hype surrounding this particular tube IMO. Fortunately I managed to stock up on the Ei KT-90 type II while Jim McShane had them. Smokes the Tung-Sol and when Ei was building them right they were bullet-proof.

There is a solution to grid current., posted on October 29, 2009 at 03:30:08

Allen Wright
Manufacturer

Posts: 4737
Location: Schaffhausen
Joined: January 31, 2002

This data is from Morgan Jones, and was originally published in Electronics World magazine. I have his permission to publicise it, and should have it on my website but been too busy. Whatever, it's more than worth a try with exxpensive NOS tubes that don't last.

------------------------------------------------------------------------

Grid current problems with never used NOS tubes.

They need to undergo a heating process to restore them to full as-new health. If stored unused for a long time, the vacuum can suffer and the tube rapidly goes noisy in use, which is a HUGE loss.

1/ Put the tubes (out of their cartons) on baking paper or alu foil, in a clean *cold* kitchen oven.

2/ Set the thermostat to 150 degrees C and allow the oven to come up to this temperature slowly.

3/ "Bake" the tubes for 4 hours at 150 degrees C (not F)

4 After 4 hours, turn off the oven but DO NOT open the door, allow the oven and tubes to cool slowly OVERNIGHT to room temp.

5/ Repack in their cartons.

The theory being that doing this re-engergises the getter and hence absorbs the free particles that have gotten into the 'vacuum" over time. It's these free particles thatbecome unwantedly active when the untreated tube is first used, and they damage the grid - and make the tube noisy/unusable.

I do all my old NOS tubes with this procedure. Good hunting!
--------------------------------------------------------------------------

Regards, Allen

I'm gussing that once they are noisy..., posted on October 29, 2009 at 15:32:03
Ivan303 Audiophile Posts: 15857 Location: San Francisco Joined: February 26, 2001	it's too late?

"That once they are noisy..., posted on October 29, 2009 at 16:24:40
Allen Wright Manufacturer Posts: 4737 Location: Schaffhausen Joined: January 31, 2002	...it's too late". According to Morgan, yes, the damage is already done. Regards, Allen

How can I test for grid current..., posted on October 29, 2009 at 18:59:50

Ivan303
Audiophile

Posts: 15857
Location: San Francisco
Joined: February 26, 2001

other than to measure the voltage at the grid which should be the same on either side of the grid resistor if there is no current going through the grid resistor?

Am not clear what you mean by..., posted on October 31, 2009 at 12:41:33
Allen Wright Manufacturer Posts: 4737 Location: Schaffhausen Joined: January 31, 2002	..."grid resistor". I measure the voltage on the grid itself, with reference to gnd. If the R from grid to ground is high enough, grid current shows itself as millivolts of grid voltage, and I've seen as much as a hundred millivolts on bad tubes. Regards, Allen

Yes, of course...., posted on October 31, 2009 at 17:01:49
Ivan303 Audiophile Posts: 15857 Location: San Francisco Joined: February 26, 2001	the reason I didn't mention ground is because of the case where the grid is biased by a bias supply rather than cathode bias where the grid is at ground. In the case of cathode self bias, the grid resister is between the cathode and ground

Can I use this method....., posted on October 29, 2009 at 12:07:47
amandarae Audiophile Posts: 1324 Location: So.Cal Joined: November 30, 2004	....on notoriously noisy tubes like 37 and/or 76 ST type? What about 6SN7's? thanks! Abe DIY, all the time!

How would I know?, posted on October 29, 2009 at 16:29:10
Allen Wright Manufacturer Posts: 4737 Location: Schaffhausen Joined: January 31, 2002	I have passed on info from a well known tube expert, and I have tried it myself successfully. It's to repair never used NOS tubes that have grid current on first usage - which rapidly turns into noise and tube damage. Why your mentioned tubes are noisy I can't say - if they also have grid current then I'd say give it a go, it can't hurt. Regards, Allen

Thanks (NT), posted on October 29, 2009 at 16:49:09
amandarae Audiophile Posts: 1324 Location: So.Cal Joined: November 30, 2004	NT DIY, all the time!

I had one of my newer slightly used vintage genelex kt88s, posted on October 29, 2009 at 05:05:59

Michael Samra
Dealer

Posts: 13134
Location: saginaw michigan
Joined: January 30, 2005
Contributor
Since: June 24, 2005

that would lose conductivity after 3 minutes and you could rap on the tube to make it come back.I resoldered the tube pins and that didn't help so a year later I got that same tube back out and set it in my heath TT-1 tester and left it on for like 6 hours. I then put the tube in the citation 2 and biased it and have run the tube for 2 weeks and all seems well.
If the power supply waveform isn't pretty,neither is the sound in most cases.

Have you sucessfully applied this method to TS 6550's?, posted on October 29, 2009 at 04:16:44

XLR8OR
Audiophile

Posts: 311
Location: Sydney
Joined: August 30, 2005

I'm keen to try anything to rejuvenate these tubes. Even the 10 volt heater trick for 30 to 60 secs in the hope of removing any cathode poisoning.

I haven't read of any successful methods though of removing grid leakage on these tubes except for one method that involves running these tubes for several hours using a grid voltage derived from a well regulated very low impedance source and watching the grid current reduce with time. I just wish such a rejuvenating unit was readily available. If anyone has any further info please let me know (TIA).

No, because I don't have any (nt), posted on October 29, 2009 at 10:01:48
Allen Wright Manufacturer Posts: 4737 Location: Schaffhausen Joined: January 31, 2002

Page processed in 0.059 seconds.

Tubes Asylum

6550 Tungsols anyone?

97.84.146.37