Siemens EL34s

[strato17]

I ordered a pair of NOS Siemens EL34s from KCA about a month ago. I got them in about a week ago and put them in tonight. Mind you, I had been using GT EL34M's at a #4 distortion rating. The GT's weren't bad, but they were not as smooth sounding as I preferred. I threw them in and checked the plate voltage... V4 was at 414 and V5 was at 411. These were higher measurements than my GT's which were at 400 and 404.

Me being the dummy I am, I didn't minimize the bias pot, and when I measured the cathode current, I read 65 mA!! I quickly turned the amp off and adjusted the pot. I am now running at about 43 mA. Is it possible that I damaged the tubes?

Anyways, these tubes are a HUGE improvement over the GT's. The top end has almost nothing that resembles "fuzz" and the overall sound is as smooth as glass. It seems that the amp is much more harmonically intense. I will definitely stock up on these!! I took some videos tonight... hopefully I can get them up soon.

[gahult]

I think you will be OK if they didn't red plate on you. Cherry red glow for any length of time.
Maybe some one else can be of help. More assuring.

Gary

[Wayne]

I assume in your post you meant mA when you said "VDC".

You should be fine - the tube with the highest voltage wound up dissipating 26.9 watts. Once you allow for the fact that some of that power was dissipated in the screen grid, you're operating within the limit for the tube, which is 25W.

Now, if you played the amp before checking bias you probably over-dissipated. Provided that it was only momentary, you should still be fine. One of the virtues that make NOS tubes desirable is that they are "tougher" than new production.

There but for the grace of God goes me - I almost never think to make the bias "safe" til I've got the new tubes in. No catastrophies yet!

W

[strato17]

I assume in your post you meant mA when you said "VDC".

Well, yes and no. I was using the cathode resistor method, so I was using my DMM to read VDC from pin 8 to ground across a 1 ohm resistor. But in this situation, 1mVDC is equivalent in measurement with 1mA. Anyways, I fixed it in the post.

Glad to hear that I didn't screw anything up... hopefully. I am working on getting some videos up now.

[strato17]

Here is the video... the mic still overloads a bit. Make sure you watch it in high quality!

http://www.youtube.com/watch?v=K1IdZQUPO-E

edited by request.

[Rimy]

strato
the same with my amp and the tungsram.
i love the sound, but the hiss is about 4db above some new standard tubes
so i had to put it in v2 to get rid of the hiss.
now it's fine with tung sol in v1+v3 and mullard's el34.
the sound of the tugsram still comes trough.
but i still try to get some nos 12ax7 with less hiss.

and your video... nice playing, nice sound!!!

[leleduke]

Here is the video... the mic still overloads a bit. Make sure you watch it in high quality!

http://www.youtube.com/watch?v=K1IdZQUPO-E

At the beginning, listen for the high pitched squeal. That would be a Tungsram 12AX7 that I bought off a member on this forum at a premium, which was guaranteed to be low in microphonics. When I inquired about the excessive microphonics problem, I was given a link to purchase a tube damper from their website, which was also being sold at a premium.

I love the sound of the Tungrsam, but I will either need to get some kind of damper for this one, or drop the change on a new one

Great tone

[stevek66]

Here is the video... the mic still overloads a bit. Make sure you watch it in high quality!

http://www.youtube.com/watch?v=K1IdZQUPO-E

At the beginning, listen for the high pitched squeal. That would be a Tungsram 12AX7 that I bought off a member on this forum at a premium, which was guaranteed to be low in microphonics. When I inquired about the excessive microphonics problem, I was given a link to purchase a tube damper from their website, which was also being sold at a premium.

I love the sound of the Tungrsam, but I will either need to get some kind of damper for this one, or drop the change on a new one

If the tube has excessive microphonics send it back and get a replacement.Guaranteed to be low microphonic,yes?
When it comes to NOS tubes I buy from Mika@KCA.
Example:about a month ago I wanted a Amperex BB for a backup to the one I use in my Express.Mike sent me one,I tried it and it was to microphonic in V1.So i called him up,told him the problem.Bingo,tube replaced.Don't settle.
Steve

[stevek66]

The clip sounds great by the way
Steve

[drhulsey]

Here is the video...

Very nice I love that song: Shaky Ground

[Jana]

I was using my DMM to read VDC from pin 8 to ground across a 1 ohm resistor. But in this situation, 1VDC is equivalent in measurement with 1mA.

ummm... 1 volt across 1 ohm = 1 amp (1000ma.).

[Allynmey]

Here is the video... the mic still overloads a bit. Make sure you watch it in high quality!

http://www.youtube.com/watch?v=K1IdZQUPO-E

At the beginning, listen for the high pitched squeal. That would be a Tungsram 12AX7 that I bought off a member on this forum at a premium, which was guaranteed to be low in microphonics. When I inquired about the excessive microphonics problem, I was given a link to purchase a tube damper from their website, which was also being sold at a premium.

I love the sound of the Tungrsam, but I will either need to get some kind of damper for this one, or drop the change on a new one

Nice sound! The Tungsrams (Hungarian) are the goods for this amp. But, you'll have to go through a few to find the right one. I also use Pre-war Ei's. I go through about 20 tubes to find V1 and V2 when I tube an amp. Takes a long time. send the tube back and get a new one if you bought it as low noise.

Allyn

[strato17]

I was using my DMM to read VDC from pin 8 to ground across a 1 ohm resistor. But in this situation, 1VDC is equivalent in measurement with 1mA.

ummm... 1 volt across 1 ohm = 1 amp (1000ma.).

duh.... sorry my mind was all over the place last night

[Lousyatit]

You really do have a nice touch, great stuff!

[novosibir]

At the beginning, listen for the high pitched squeal. That would be a Tungsram 12AX7 that I bought off a member on this forum at a premium, which was guaranteed to be low in microphonics. When I inquired about the excessive microphonics problem, I was given a link to purchase a tube damper from their website, which was also being sold at a premium.

I saw the prices, he's asked for the Tungsram in the Sale/Trade forum - not a bargain at all IMO! And for this price you shouldt get a tube, where not an additional crux is needed, to make it work properly as a V1

Among Tungsram there are only about 20%, which you can regard as 'very low noise/low microphonic' - another 20% unfortunately do have hum, excessive hiss or crackling issues, so that they simply are garbage. So when he's sold his premium 20% and thrown away the other 20%, then he can't go and sell some more out of the remaining 60% 'as V1' for the same price!

6 of the 7 preamp tubes in my DINO and 3 of the 6 preamp tubes in my British Purist are NOS Tungsram. Through my hands went hundrets of NOS Tungsram in the past few years - so I know, about what I'm speaking!

Go and get another Tungsram from him, which IS a V1 - or try to get your money back!

Larry