What amp
What tube types
What plate voltage
How (hot) you run the amp (i.e. hoe hard you drive it, not necessarily how loud it is)
What speaker(s) you use
What style you play

Beyond that - "brand" may not be your best way to choose tubes. Place of manufacture of the particular tube type is generally more important. For example, you could say "Groove Tubes", "Sovtek", "Fender", Electroharmonix" - and they might all be the same tube.

but - if you say "New-Old-Stock U.S. RCA Blackplates" - that's a particular tube. OTOH, "Russian short-base 5881" is a particular tube that could carry any one of about 6-10 brand names. And isn't even a 5881.

I currently am feeding my 59 tweed bassman (NOT a reissue)the reissued Tung-Sol 5881. Yes, this is a Russian reissue. I previously only used NOS Tung sols and Sylvanias. (Because I could get them reasonably) The new tubes are decent, but you get what you pay for. I always rebias after a replacement and check plate voltage. I know what my amp likes, and more importantly know what my ears like. The reissue tubes compress a bit more, but I can live with that. They do sound good. I suspect I won't get the life I get from USA made NOS tubes. This amp gets played at 3 gigs a week, so it is getting ample use. I think Sovteks are ok when the amp is running optimal, but don't expect to get longevity out of them. NOS tubes seemed to be made with better materials and lasted longer in my experience. But, in a gig situation IF I can get the tone out of a $40 set of tubes for 6 months, and have to replace them, that beats spending upwards of $120 on precious NOS Tung Sols each year. That supply will eventually run out, that sthe reality of it. What I have been doing is saving my old NOS tubes while they still have life left.

Unfortunately the "best tube" conversation in my experience has been based on a whole lot of opinion, marketing and false claims. Both on so called "expert" repair guys and modern tube manufacturers.

Try different tubes, get the amp set up right and your ears will tell you whats good and whats not. When you get the amp biased, make sure you are there with YOUR guitar as the tech adjusts it. A good tech will let you play the amp in between settings around the nominal set up. You can be the judge on the tone in the end. after all, you gotta play the amp!

Unfortunately this "game" we are all in isn't cheap, and that makes it difficult to go out and buy $200 in tubes just to "try".

good luck and as always, have FUN!

That's the reason I was asking him for more info about the amp. Hard to define "best" tubes when they could be going in a Fender, Vox, Marshall (or whatever) - all of which can use any of several types of tubes before you even GET to brand and then model. 6L6, 6V6, EL84, EL34, 5881, 6550 KT88...there are a LOT of power tube types. then, a lot of brands. Then, a lot of models of each tube within those brands.

The amp I have is a Vox Cambridge Reverb from the 60's with a 10 inch bulldog speaker.

1. I suggest reading the Watford Valve reports here for current status on EL-84/6BQ5 and 12AX7-style tubes:
http://www.watfordvalves.com/reports.asp

These guys do pretty serious testing and check out the gamut of what's available these days. It is, of course, their opinion, but I find their reports useful.

2. On preamp tubes, I don't find brand distinctions all that useful. I have to just try different tubes to see what works. They are fundamentally different than the power tubes. With power tubes, there is the issue of reliability under the plate voltage. With preamp tubes, that isn't nearly as big an issue - it's mainly tonal preference.

3. A lot of this really does depend on the style you like to play, what kind of guitar/pickups you have, what kind of tone you like - distorted, clean, etc., and so on.

With that said, a lot of people like the NOS Telefunken, Mullard, or Amperex/Bugle Boy 12AX7/ECC83 or 12AU7/ECC82 tubes in Vox tube amps. You can even play around with different tube types. For example, if you want to clean up the sound, try substituting a 5751, 12AT7,12AY7, or 6072 for the 12AX7. Or if you want to dirty it up a bit, perhaps substitute the 12AV7 for the 12AU7. I put a relative nominal-gain chart for these preamp tubes here:
http://steelguitarforum.com/Forum11/HTML/006922.html

On the EZ81/6CA4 rectifier tube - I assume you mean 6CA4, not 6AC4 - I don't even know if they have been reissued. The main issue with rectifier tubes is reliability - they aren't in the signal path, and only affect tone to the extent that they do or do not deliver a consistent voltage without "sag" as the amp is pushed.

You might want to check out Angela Instruments, http://www.angela.com . I have found him to be a good source for NOS tubes in general, but - IMO - do your homework and know what you want before dealing with a source like this.

[This message was edited by Dave Mudgett on 17 March 2006 at 12:57 AM.]

For EL84's you are MUCH better off with Amperex, Telefunken, Mullard etc. Expensive, but worth it. Most of the newly-manufactured EL84's are flat awful.

For your "AX7" (I'm assuming that's a "12AX7"), RCA, Telefunken, Sylvania and Philips are all good. JJ makes decent new ones. The Sovtek 12AX7LPS can be good, but half of the ones I've gotten are noisy. For 12AU7's stick with NOS U.S, British and German tubes for sure.

And yes, that's a 6AC4. A little tough to find, so you'll be a bit more limited on choices.

The venerable Tube Lore - A Reference for Users and Collectors book by Ludwell Sibley also lists them this way.

I play all Hawaiian on the steel and I use a lot of chimes in my playing. I do pump the volume up to a fairly loud level.

Here's a pic of the Vox schematic for that tube. Mis-print?

Just curious, but does anyone know what brand of tubes that originally came with this model of Vox?

I have a copy of the same Vox schematic.

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My MP3's, Pics, & Video

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There's even an Allied Radio cross-reference for the 6CA4

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You mean 6AC4? Yes, I saw that. Let's summarize:

Allied Electronics equivalents: UU12-6AC4 (doesn't say anything about EZ81)

Vox schematic: calls for EZ81(6AC4)

But I can't find any source for 6AC4, all the other references cross-list EZ81-UU12-6CA4 together, and every single vendor source I could find sells EZ81/6CA4. That is why I conclude that the Cambridge Reverb rectifier is EZ81/6CA4.

Yes, the Vox Pacemaker is basically a Vox Cambridge Reverb without reverb - here's a good source of info on this kind of thing:
http://www.voxshowroom.com/equipment/index.html

Again, the Free Info Society website has the relevant schematic:
http://www.freeinfosociety.com/electronics/schematics/audio/voxpacemaker.pdf

Note that this schematic references the EZ81/6CA4 rectifier, not 6AC4.

The original tubes were probably Mullard - they were pretty much stock in 60s Vox amps. Yeah, they're pretty ridiculously priced now, but great tubes. The European nomenclature is ECC83(12AX7), ECC82(12AU7), EL84(6BQ5), and EZ81(6AC4?6CA4). The tube number in parentheses is just the standard American equivalent - but the actual European tubes are ECC83, ECC82, EL84, and EZ81. At the very least, 6CA4 is a reasonable choice. If there is, in fact, such a thing as a 6AC4 and if further, it is equivalent to EZ81, well that will work also. Happy hunting, if that's what you want.

The other issue is that similar rectifier tubes can often be substituted. Some lists indicate that 6V4/EZ80 can be substituted, but doesn't have quite as high a current capacity - sort of like substituting a 5U4 rectifier for a 5AR4 - they probably sag a bit more, perhaps good if you want a little more compressed sound. Be careful if you do that, however - it's not always a good idea.

Jay, I totally agree that the 7581a/6L6GC tubes are a great choice for clean Twin-family applications. I have used the 80s Philips/Sylvania versions made in Emporium, PA. The Watford Valves reports I referenced above lay all this out pretty clearly - they give a lot of test details on a lot of currently available tubes. Obviously, I agree with you about trying different gain mini-preamp tubes to get the sound you want. I also find that 12AX7 tubes tend to have too-high gain for pedal steel, and right now am using a 5751 in the front gain stage of my Dual Showman Reverb. But for lap steel, I usually prefer more distortion/compression. I love to crank up these small EL84 amps with my Ricky Bakelite.

[This message was edited by Dave Mudgett on 18 March 2006 at 09:33 AM.]

[This message was edited by Jay Ganz on 18 March 2006 at 07:26 PM.]

It's a few years old, but has real good data. I like how they review tubes for both hi-fi audio as well as guitar amps. Since steel guitar kind of falls into both categories, the info was very useful. It was very timely to read for me because I've recently been messing with the EH 12AX7, the Sovtek LP (long plate) 12AX7-LPS, and the JJ 12AX7 (ECC83s). The preamp I've been making has a 12AX7 in the gain/eq section. I've been using the JJ and the Watford article confirmed exactly what I was hearing. Recently I've been messing with the Sovtek Long Plate 12AX7-LP and LPS. Now that is also a very nice sounding tube. I had messed with those in my Deluxe and Twin too. As far as preamp tubes go, I'd have to say that two of my favorite new and affordable tubes are these two;

Sovtek 12AX7-LPS (or LP if you have DC heater supply)
JJ 12AX7 (ECC83s)

Both of these have a warm and even top end, and a smooth, sweet sound. Many of the others have a bright upper midrange and a "forward" sound. For me it seems that on steel it's nice to have a smooth and warm tube. The JJ has a more "detailed midrange" and the bass is kind of big and compressed. The Sovtek LPS has a tighter, stiffer bass response. Both have a top end that's easy on the ears and not harsh. The Sovtek Long Plate tube is a bit notorious for microphony and I've experienced this myself. They may be better suited for preamps or positions where they're not physically mounted in the cabinet subjecting it to the vibrations of the speaker. The JJ's are better in this regard.

Many other 12AX7's both new and old are bright sounding. The bright, snappy sounding tubes can be a bit much on steel, but that depends on the style and context I guess. If you want to spend big bucks, the Mullards and Telefunkens are hard to beat.

You can really change the tone of a tube amp by choosing the right preamp tubes. Read up on them and then you can probably help to dial in the sound you want. Sometimes I hear people complain that their re-capped and re-tubed Twin or Vibrosonic is too bright or edgy. I think that you can really control or tame this with the right selection of 12AX7's.

I've learned recently that Sovtek has more than one factory, and the quality of their tubes varies widely. Many of us are familiar with the Sovtek tubes that come stock in many commercially popular amps. These tend to be the lower grade, run-of-the-mill Sovtek tubes. Some of the other Sovtek tubes are actually quite nice sounding and are of good quality. The EH branded tubes are supposed to be the higher grade Sovteks, but they tend to be the brighter sounding ones.

Brad

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You can really change the tone of a tube amp by choosing the right preamp tubes. Read up on them and then you can probably help to dial in the sound you want.

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Absolutely. They can make a huge difference, and you really can tailor the sound. I have a big box full of new and NOS preamp tubes in many varieties. After I get a new amp, I either clean it up and replace caps or give it to my buddy Dave Sarge to do it for me. But then I spend some time figuring out which are the right tubes. It may take an afternoon, but it's worth it, IMO.

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Steel players do it without fretting

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[This message was edited by basilh on 20 March 2006 at 01:26 PM.]