ID tubes from 1968 Traynor YVM-1

[thehoj]

I recently snatched this Traynor YVM-1 for a steal and was kind of curious how I made out with the tubes.

Firstly the amp is just an excellent specimen. http://i.imgur.com/EYF8vqp.jpg

But I'm curious about these tubes. Can anyone shed some light on them?

7025:
http://i.imgur.com/bVJrXXb.jpg

6CA7:
http://i.imgur.com/v5x2de5.jpg
http://i.imgur.com/20RUpJf.jpg

[Jazz P Bass]

The 7025 preamp tube is a mil-spec 12AX7.
The 6CA7 is more a 6L6 than a EL34.

[thehoj]

Any idea who manufactured the 7025's? I have 4 of them identical.
In searching Holland 7025 I keep seeing the name Amperex and Phillips come up, is this who likely made these?

As for the 6CA7's, searching 6CA7 made in czech and noting the fact that the base seems to be brown, they look a lot like the Tesla's on this site https://www.tubeworld.com/6ca7.htm#tesla
Is this likely who made these tubes?

The 7025 preamp tube is a mil-spec 12AX7.
The 6CA7 is more a 6L6 than a EL34.

[Chuck H]

Amperex and Tesla get my vote

[Rhodesplyr]

The seams on the top of the 7025 are typical of Amperex/Holland, but also Mullard/UK, both of which were owned by Philips at some point. There are sometimes faint date codes around the bottom of the envelope that can provide more specific information.

I'd agree that the EL34 is probably a Tesla tube. Looks like a pretty close copy of the Mullard design. 6CA7/EL34 are sometimes used interchangeably, but the EL34 was always a pentode. The 6CA7 was an American beam tetrode version made to work in circuits designed for EL34s. (The KT77 is another beam tetrode EL34 equivalent.) Again, date codes on the glass just above the base can help nail it down if they exist.

[g1]

Can't offer any more about the actual manufacturer, but I do know that Traynors of that vintage often had Rogers labelled tubes from the factory. So that preamp tube could be original or a replacement from that time frame (L&M would have been stocking Rogers as replacement tubes at that time).
As far as the 6CA7 goes, true "big bottle" 6CA7's were beam tetrodes as Rhodesplyr stated, and, like Jazz said, were more like a 6L6 than an EL34. However at times the EL34 and 6CA7 designations were used interchangeably. I have seen "skinny' bottle versions labelled EL34/6CA7 in Traynor amps. These would not have been beam tetrodes like "real" 6CA7's. I can't tell from the picture whether yours is a skinny or big bottle.

[Chuck H]

I have seen "skinny' bottle versions labelled EL34/6CA7 in Traynor amps. These would not have been beam tetrodes like "real" 6CA7's. I can't tell from the picture whether yours is a skinny or big bottle.

I can't find anything about TESLA made 6CA7's. I'm guessing that those tubes are EL34/6CA7 type (meaning EL34's). And IMHO that's a good thing. If they still have life in them the old TESLA EL34's are very fine tubes. I was lucky enough to burn up a quad in my reissue plexi when I use to gig. Replacing them was unsatisfactory. I had been spoiled. I don't spring for tubes like NOS Mulllards and such. Those old TESLA's were the best sounding EL34's I've used.

[thehoj]

I can't find anything about TESLA made 6CA7's. I'm guessing that those tubes are EL34/6CA7 type (meaning EL34's). And IMHO that's a good thing. If they still have life in them the old TESLA EL34's are very fine tubes. I was lucky enough to burn up a quad in my reissue plexi when I use to gig. Replacing them was unsatisfactory. I had been spoiled. I don't spring for tubes like NOS Mulllards and such. Those old TESLA's were the best sounding EL34's I've used.

Thanks for the info everyone.

Here's the funny thing.. For some reason I assumed that both power tubes in this amp were the same, but tada http://i.imgur.com/17zmQvr.jpg here's the other tube.. it's also physically a bit taller than the sylvania labelled one.. not sure how I missed that.

At least they're both (likely) el34's lol.. That being said, I think the Telefunken marked one might be on the way out.. I'm getting some totally random crackling and fizzling coming from the amp, and it seems to be agitated when I tap that telefunken.. It seems to move with the tube too.. So I'm thinking I'll probably have to locate a new pair of el34's for this amp unfortunately. I'll try replacing the power tube sockets first I think though.

[dai h.]

EL34 looks like a Tesla (not the same as JJ from what I understand). Could be more certain if the pins were shown (they have those stupidly fat pins that help to stretch out tube socket pins--which isn't a problem if you use them exclusively--but standard pins aren't as fat).

7025 might be Holland made but (in general) for tube ID you want clear pics of the external and internal structure (bottle shape, plate, getter, etc.) and any possible identifying marks (etched codes, numbers, markings on the bottom, etc.) and not enough is shown so it's harder to tell especially if it's a common-looking type with a less distinctive structure (plates, bottle, etc.).

[Rhodesplyr]

The Telefunken does look like other real Telefunken EL34s pictured online. You also find Siemens EL34s labeled Telefunken, but they are skinnier with a dimple on top.

[thehoj]

EL34 looks like a Tesla (not the same as JJ from what I understand). Could be more certain if the pins were shown (they have those stupidly fat pins that help to stretch out tube socket pins--which isn't a problem if you use them exclusively--but standard pins aren't as fat).

Come to think of it the Sylvania labelled one is a tight fit into the sockets, and the telefunken almost slides into the sockets.. It does seem like the pins are thicker, and I'm wondering if that's why the telefunken seems to crackle when tapped... because the pin sockets are stretched out.

[dai h.]

might be a good idea to check since it'd be a big waste if a loose control grid pin or whatever led to damage (esp. if it turned out that nothing was actually wrong with that rare tube (99.999% certain that is a real W.German Tele)).

[thehoj]

I found a couple resistors that were flaking out in the amp, and have since determined that both of these power tubes are okay.. Crackling doesn't seem to be coming from the telefunken.
Is there any problem with running these two different makes of el34? My understanding is that there wouldn't be any issues as long as they're both biased correctly, even if they are somewhat mismatched.

[g1]

No problem. A real mismatch is when one of the 2 power tubes has fallen out and is sitting in the bottom of the cabinet and the customer says "it's been sounding funny for a couple weeks now" . Still have never seen any real damage from those kind of scenarios.
Some folks who like asymmetry will even run a pair of dissimilar tube types.

[thehoj]

No problem. A real mismatch is when one of the 2 power tubes has fallen out and is sitting in the bottom of the cabinet and the customer says "it's been sounding funny for a couple weeks now" . Still have never seen any real damage from those kind of scenarios.
Some folks who like asymmetry will even run a pair of dissimilar tube types.

Ha nice.

I was thinking that maybe there is some asymmetry contributing to the particular sound this amp is making. I seem to be finding a variety of info on Telefunken but I'm gathering that they're more popular with the hifi crowd..more of a full range tube from what I've read.
People talking about the Tesla's seem to think they break up earlier, sing more from a guitar amp standpoint.. I dunno. I have nothing to compare them too.. But the two contrasting reputations that these tubes have are perhaps creating a unique sound.
I ordered a matched pair of EH EL34's, so it'll be interesting to compare the sound.