NOS Valvo El84 Question

[larrylover]

I just received one pair of Valvo EL84 tubes that were represented to be NOS. When I received them, the Valvo lettering and design on the outside of the tubes was white. I put them in my amp with a 2XEl84 power section made by local Chicago amp maker/fixer/luthier Tim Schroeder to make sure they work. They seemed to work fine, but after only 5-10 minutes of playing the lettering on both tubes had turned light brown.

Does this quick coloration indicate anything wrong -- either with the tubes (not authentic, for example, old) or with the amp? Thank you.

[Sparky6string]

I've heard of some tubes that do that. I'd say what it most likely says is that the tubes had genuinely never been used before.

[rreiser]

Probably new, maybe the tubes are running a little hot and the lettering turned brown. Did you notice any plateglow?

[Blue Strat]

Hard to say for sure, but if turning brown when heated is of concern, they'd already be brown if they were used, right?

It's quite possible that they're running too hot in your amp. Most EL84 amps run their power tubes way too hot.

[Timbre Wolf]

Check for the etched codes near the bottom side of the glass in order to authenticate the tubes. There should be two lines of letters/numbers, with the second one beginning with D for Valvo's Hamburg factory.

You'll want to be sure someone didn't slap some fresh paint on a new-production tube.

-Thom

[Blue Strat]

Check for the etched codes near the bottom side of the glass in order to authenticate the tubes. There should be two lines of letters/numbers, with the second one beginning with D for Valvo's Hamburg factory.

You'll want to be sure someone didn't slap some fresh paint on a new-production tube.

-Thom

Excellent point!

[larrylover]

Thank you very much for the thoughts. The writing on the bottom part of the glass is incomplete -- looks worn away -- on allfour tubes. The one that appears to be most complete is very hard to read -- the lettering is dark -- and appears to have two rows that each have three letter, numbers or symbols: first row: soemthing (can't make it out) x 4; second row: = with slash through it, 6 (or 0) F. There is also white lettering at the top of the tubes, although can't make it out.

Any further thoughts would be appreciated. Thanks again.

[rockon1]

pictures?

[Timbre Wolf]

Thank you very much for the thoughts. The writing on the bottom part of the glass is incomplete -- looks worn away -- on allfour tubes. The one that appears to be most complete is very hard to read -- the lettering is dark -- and appears to have two rows that each have three letter, numbers or symbols: first row: soemthing (can't make it out) x 4; second row: = with slash through it, 6 (or 0) F. There is also white lettering at the top of the tubes, although can't make it out.

Any further thoughts would be appreciated. Thanks again.
The first row, first character would be an "r" for "rx4" (EL84 code). The first character of the second line identifies the manufacturer as another West German company, Siemens, not Valvo's Hamburg production. They were probably legitimately re-branded by Valvo to meet the quota at the time, which was probably 1970 (if that is a 0 and not a 6).

I can't comment on Siemens vs. Valvo sonic quality, as I haven't any experience with the Siemens.

Sometimes it helps to fog up the glass with your breath before attempting to read these codes, by the way.

- T

[larrylover]

The first row, first character would be an "r" for "rx4" (EL84 code). The first character of the second line identifies the manufacturer as another West German company, Siemens, not Valvo's Hamburg production. They were probably legitimately re-branded by Valvo to meet the quota at the time, which was probably 1970 (if that is a 0 and not a 6).

I can't comment on Siemens vs. Valvo sonic quality, as I haven't any experience with the Siemens.

Sometimes it helps to fog up the glass with your breath before attempting to read these codes, by the way.

- T

So looks like legitimate, probably my amp running hot.

Thank you very much. Is there any guide that I can buy that would provide information such as what to look for on tubes (such as the coding at the bottom of Valvo tubes that you suggested I look for) and decoding the codes?

[Sparky6string]

Is there any guide that I can buy that would provide information such as what to look for on tubes (such as the coding at the bottom of Valvo tubes that you suggested I look for) and decoding the codes?

http://www.audiotubes.com/mullcode.htm

[Timbre Wolf]

Is there any guide that I can buy that would provide information such as what to look for on tubes (such as the coding at the bottom of Valvo tubes that you suggested I look for) and decoding the codes? There isn't any comprehensive guide, unfortunately. It'd be nice if there was. Until that time, it doesn't hurt to ask here.

- Thom

[Mike9]

Bottom line is - how do they sound? I have Amperex EL84s and 12ax7s in my Crate VC20 and they are wonderful sounding tubes.

[larrylover]

Thank you very much for all of the help. I appreciate it. Mike9, not sure how they sound yet. I just got them and could only test them late at night with volume low. First thing was to make sure they actually work in case I have to deal with that fact. I have Siemens E84Ls in the amp now -- can take higher plate voltages, last longer and have a bit more headroom than el84s. I really like those. I am interested to hear the Valvos in the amp and will probably put them in in a few weeks after a current effort is concluded. I have amperex long plate 12ax7 in V1 and mullard 10m 12ax7s in v2 and v3. Really like these preamp tubes.

[cochese]

I just received one pair of Valvo EL84 tubes that were represented to be NOS. When I received them, the Valvo lettering and design on the outside of the tubes was white. I put them in my amp with a 2XEl84 power section made by local Chicago amp maker/fixer/luthier Tim Schroeder to make sure they work. They seemed to work fine, but after only 5-10 minutes of playing the lettering on both tubes had turned light brown.

Does this quick coloration indicate anything wrong -- either with the tubes (not authentic, for example, old) or with the amp? Thank you.
The amp I use was designed around current EL84's. NOS tubes are not recommended by the manufacturer. The EL84's on my amp see 400+ VDC at the plates. NOS tubes are rated for 300 volts DC. You should probably check with amp designer to see what tubes are recommended.

The following is only my opinion so take it for what it's worth. When an an amp is designed around specific components (say newer tubes) using older tubes may not always give you better sound. I think the NOS tube use is better suited to older amplifiers that were designed around these tubes. Some amps are designed around inefficient tubes for a reason. The break up quicker and have a different response than a more efficient tube. In the end I think you have to look at the overall design and not base everything on a single component. My old Rivera amp used German EL34's and had two channels. One was a Fender sound and the other a Marshall sound. To me the amp always sounded better doing the Fender thing versus the Marshall thing and this was using EL34's instead of 6L6's.

[Timbre Wolf]

I have Siemens E84Ls in the amp now -- can take higher plate voltages, last longer and have a bit more headroom than el84s. I really like those. I am interested to hear the Valvos in the amp
Here's a factoid to further confuse tube i.d. issues: "Siemens"-labeled tubes have often turned out to be RFT-made (East German company, not the West German Siemens). The "=" with a slash through it is the etch code symbol for true Siemens tubes, such as those you've got labeled "Valvo." :crazy

- T

[bluesforstevie]

No, the real NOS lettering is not only very fragile, but turns brown quickly. You may also smell the paint from the lettering burning on a new pair of tubes..Once this happens though, the tubes will be stable, and so will the logo.

This is good. Means your tubes haven't been in a circuit previously.

[larrylover]

The amp I use was designed around current EL84's. NOS tubes are not recommended by the manufacturer. The EL84's on my amp see 400+ VDC at the plates. NOS tubes are rated for 300 volts DC. You should probably check with amp designer to see what tubes are recommended.

The following is only my opinion so take it for what it's worth. When an an amp is designed around specific components (say newer tubes) using older tubes may not always give you better sound. I think the NOS tube use is better suited to older amplifiers that were designed around these tubes. Some amps are designed around inefficient tubes for a reason. The break up quicker and have a different response than a more efficient tube. In the end I think you have to look at the overall design and not base everything on a single component. My old Rivera amp used German EL34's and had two channels. One was a Fender sound and the other a Marshall sound. To me the amp always sounded better doing the Fender thing versus the Marshall thing and this was using EL34's instead of 6L6's.

Thanks for the advice. The amp designer sold me the NOS preamp tubes to use in his amp. He also highly recommended NOS power tubes. His view is that reliability can be maximized with using new tubes, but these tubes cannot touch the sound quality of NOS.

[larrylover]

Here's a factoid to further confuse tube i.d. issues: "Siemens"-labeled tubes have often turned out to be RFT-made (East German company, not the West German Siemens). The "=" with a slash through it is the etch code symbol for true Siemens tubes, such as those you've got labeled "Valvo." :crazy

- T

Thank you. Yes, I am aware of the RFT/Siemens thing and the significance of the "=" with slash. Apparently, some tubes -- EL34, I think, labeled Philips were also made by RFT, while some Philips-labeled EL34 tubes -- Philips owned Mullard -- were made in the Mullard Blackburn plant. And, I have some RFT-made EL34 tubes for which I paid $70 for the pair -- a veritable bargain in NOS EL34 tube land -- that are incredibly good. And, as is readily apparent from this thread, I am a piker and newcomer to this.

Thank you again for all of your help. I really appreciate it.

[larrylover]

No, the real NOS lettering is not only very fragile, but turns brown quickly. You may also smell the paint from the lettering burning on a new pair of tubes..Once this happens though, the tubes will be stable, and so will the logo.

This is good. Means your tubes haven't been in a circuit previously.

Interesting. I have seen the coloration happen over much longer periods of use, not as quickly as this. But this is good to know. Thank you.