Winged C SVEL34

[Mark Black]

Lord Valve at NBS Electronics in Denver does. He was unsatisfied with the Maxi Matcher so he built his own testing/matching/torture equipment. He goes pretty far out of his way to know the score on pwr tubes before he offers them for sale.

Thanks - I've known of Lord Valve for some time, but tend to forget about him since I haven't recently visited the newsgroups he either posts or used to post in.

Just had another example of failure right out of the box yesterday on supposedly tested/graded new production 6L6's (not from LV). Hit the standby and BANG! Dead short plate to heater, in a Music Man with grounded heater winding...

[Amp Kat]

An output transformer doesn't present a perfectly matched load to the output tubes, so dead nuts matching isn't needed. Close is close enough.

Some do and some don't. Some and an elite few are perfect to the inth degree where as some can be as much as 5 to 10 ohms or % in ratio off. Most Hi-Fi OT's are very good and some Guitar mainly Vintage are dead on but yes it can be deceiving and a moot point and I agree that close is close !

[jar0ahr]

JJ E34L red plate issue

Hi Gtr_tech,

About JJs EL34, I've read too many redplates issues. It seems
that just only the Eurotubes.com's ones are working fine.
As the reliability is a big matter for me to deal with, I'd prefer walking on a more sure way.

Kind regards

I just sent back a quad of JJ E34L's (not EL34's) to tube depot. I put them in my marshall tsl 100 and biased them to 90 per spec and they were okay for a few minutes. I smelled "hot electronic" smell and looked in the back and one of the new tubes was glowing orange across the whole plate area. I immediately tried to turn down the bias, it had spiked to 340ma, it would not go down, before I could turn off the amp the main fuse blew. The tube got so hot that it discolored the red paint to dark burgandy. I let everything cool down and swapped the pairs to see if it was an amp or tube issue and it started to do the same thing. This time I shut it down in time and replaced the tubes with some new svetlana's and all is well now. I am awaiting the replacement JJ tubes now.

[lea_hc]

Hello,


I have read all posts and I want to tell you my situation. Keeping in mind possible redplate problems and bias stability issues with JJ's, I ordered 12 new svetlana - (new sensor) tubes form tubestore. Two of them came with their pins 2 or 7 without soldering and a third one failed after 10 hours of use because of the same bad soldering matter. Therefore, beyond matching, and even beyond sound textures, I'm only seeking reliability. Reliability both in the brand as in the Distributor. Think that it's not so easy returning back damaged tubes form Argentine.
Best Regards
Lea
PD.: I've heard to bias JJs in the coldest possible way.

[Satamax]

Hello,


I have read all posts and I want to tell you my situation. Keeping in mind possible redplate problems and bias stability issues with JJ's, I ordered 12 new svetlana - (new sensor) tubes form tubestore. Two of them came with their pins 2 or 7 without soldering and a third one failed after 10 hours of use because of the same bad soldering matter. Therefore, beyond matching, and even beyond sound textures, I'm only seeking reliability. Reliability both in the brand as in the Distributor. Think that it's not so easy returning back damaged tubes form Argentine.
Best Regards
Lea
PD.: I've heard to bias JJs in the coldest possible way.

Lea, i've had the same kind of stuff with thoses tubes, flying getter ring in the tube. I had bought something like 20 unmatched ones. Two or three were verry high, needing like 6L6 bias, one or two real low and one with the getter not even atached in the tube. But mathias always set thing straight. all in all, it was not that bad a deal.

>Bye.

Max.

[lea_hc]

Somebody knows the reputation of vacuumtubes.com?
Thanks a lot

[lea_hc]

Somebody knows the reputation of vacuumtubes.com?

[Rick Erickson]

I put them in my marshall tsl 100 and biased them to 90 per spec and they were okay for a few minutes.

That's 90mA per pair right? 45mA/tube. Unless your Plate-to-Cathode Voltage is 400V or less, I would not run them that hot. I think Marshall messed up on their bias spec for these amps. I generally ignore the "spec" and set the bias where I think it should be. The strange thing is, Marshall usually sends their amps out running very cold, presumably to make the tubes last through the Warranty period.

RE

[lea_hc]

I put them in my marshall tsl 100 and biased them to 90 per spec and they were okay for a few minutes.

I agree with Eric that it's a very hot bias. Linearity is a donīt care for Marshall's, so why overheating the tubes?

Lea