12ax7/7025 tube talk

[Wound_Up]

Been buying tubes recently and so I just wanted to share my experience. I initially bought 1 standard JJ 12AX7 to replace a noisy tube in my Monoprice 15w/Laney Cub 12R with 3 - 12AX7s and 2 - EL84s.

So I replaced the tube in V1 and kept playing. Next, I bought a Electro Harmonix 7025 EH. Turns out they don't like cathode followers or PI's so it went in V1 and the JJ went to V2. Next, I bought a low noise JJ 12AX7 with balanced triodes and put in V3. That made the amp quieter than it's ever been.

So I figured I'd order a "high gain" & low noise JJ 12AX7 to try in V1 and see if I liked it or not. This is where things get interesting. As soon as I hit the strings, it was clear that the 7025 EH was going back in. The JJ was pretty harsh sounding. Something you constantly read about JJ's.

So I put the 7025 back in and immediately noticed how much better it sounds. I didn't notice that when I initially installed it but I can tell you now that I will likely ALWAYS use an EHX 7025 EH in V1 after this, unless I find a better sounding tube. It's a night & day difference.

From what I know, the 7025 is just a 12AX7 made differently and with different construction methods. I believe it has a spiral wound filament which is different than a standard 12AX7. I'm not exactly sure about this 7025 tube so I may have gotten some details wrong since I'm going by memory.

I've also currently got a matched quad of Telam EL84s coming from Ukraine that I got a Hell of a deal on. The Tube Store wants $80 USD for a single tube and I got these 4 for around $43 total. All tested good.

Another guy at one of our sister forums recognized the guy in Ukraine and told me he previously bought the same kind of tubes from the guy and they all worked perfect so I'm pretty sure these will all be great tubes. Not looking forward to having to bias the amp once I install them.

Luckily there's a test point and a trim pot that makes it easy. Measure for -12.5V and adjust if it's off. I know that's not the best way to bias an amp. It's what they provide so I'll use it so I don't have to buy the tool to read plate voltage, etc...



So... I've also been wondering about some stuff. Anybody care to explain what a cathode follower is? Or a PI(phase inverter)? Or how they interact with/in an amp circuit? Would a "high gain" tube benefit a cathode follower or PI? Or a tube with balanced triodes? Low noise?

Yea, I'm pretty uninformed and uneducated when it comes to tube amps so I'm trying to learn. Thanks.

 

[mad axe man]

some people say there is no difference but this tube destroys any 12ax7 i have used...its in my 3 rivera superchamps and my 2 70s marshalls... its magical

 

[CAR63]

I use the EH 7025 in several amps with good results .

 

[Green Craig]

I bought some NOS Baldwin/Raytheon 12ax7's last year and slapped 'em into an Ibanez TSA-5 and a Vox AD30VT - given that the Vox only has 1 tube, I think this is the culprit (rather than the 6V6 in the Ibanez)...it darkened the tone somethin' fierce. The first time I plugged my Telecaster into the Vox, I double checked the tuning, man...it felt like it was playing flat.

Now, don't get me wrong, the Raytheon 12ax7's definitely improved the articulation of both amps - since the lil' Ibanez is but a 5 watt amp, the increased darkness helps cut down on the potentially shrill higher end. It added a little more tube sag to the Vox circuitry, which overall is kinda cool.

But, Raytheons (dba Baldwin or a couple other odd rebadges) noticeably darken the tone, and like I'm a dude who has a really hard time tuning by ear...so if I'm noticing dark tone, it's gonna be glaringly obvious to someone who knows wtf they're doing.

 

[Wound_Up]

Ok so I definitely do not like the "high gain" JJ 12ax7 in V1. I tried it again and even tried the standard JJ 12ax7 and the 7025 EH still wins. Its got lower gain(& noise) than the standard 12ax7 and supposed to have low microphonics just based on how it's built. Supposed to be great for combos.

Whatever the case, it sounds tons better even with less gain. I might have to try a standard EHX 12AX7 next so I can see how that sounds. I would hope it sounds similar, just with normal 12ax7 gain. If so, I might actually like that even more.

 

[Bakelite1]

Older tubes are quite different than modern ones. Thicker glass, different vacuums and much more. Tone is usually more complex but each series is going to sound unique.
I like NOS tubes but I only buy them if they've been tested. New tubes take some hours to burn in. You can get some shops to do this and match sets which is a consideration.
I don't make final judgements with fresh tubes. Some do not mature for many (40+) hours. I think they need to have variable loads (from playing) but that is open to dispute. The same applies to speakers, so this is probably familiar.
Lots of guys have a big stash of used tubes. These can be had cheap but be careful and expect some fails.
I eventually found a set for my Excelsior. I paid for matched output for V2 but that's the only new tube (a JJ ECC83s).
Good luck! I've had good results from VacuumTubes.net

 

[BlackStrat7]

@Green Craig Exactly what Baldwin branded Raytheon do you have? Are you sure it tests good? What was in there before?

The early long black plate Raytheon’s “Baldwin branded” with square better are very fine tubes. One of my favorite lbp. Baldwin or almost any popular organ branded is usually a good thing. I’ve believe the same tube with O getter came out in 62-63. Some people don’t like them as much but I like them just fine. In fact I have one in V1 of my DRRI now followed by a CBS Hytron v2. I’ve never experienced a dark Raytheon whether it be black or gray or long or short plate. Perhaps it’s a rebrand? RFTs are on the darker side and break up quickly. They’re great for rock imo. All the European Philips such as Amperex, Mullard, Siemens. etc I find to be warmer than American tubes as well but in a good way. Telefunken and Ei’s have a good bit of top end with the Teles being more neutral.

@wound up I think the EHX 7025 is a fine tube if you need low noise and microphonics. They aren’t high gain as you said and I find them to be pretty neutral. I think the current Psvanes are pretty neutral as well and can be had really cheap at TubeDepot. I always get mine checked for low micro and high gain though. I believe, I could be wrong, that it’s the same tube as the preferred series except they’re tested and handpicked like the TADs, Ruby, etc. The JJs have their place. I like their E83CC and ECC803 long plate. The standard 12ax7 or ecc83s work better in brighter high gain amps imo. I also thought the ECC83MG had its on thing in a good way. Obviously I haven’t run across too many tubes I didn’t like lol. However my favorites are the late 50s Tung-Sols, early lbp, Mullard and Amperex I63s. If you want the best sounding “neutral” tube Seimens & Halske are beautiful.

Of course all of this is with my ears, my gear and my amps lol. But I think descriptions a pretty accurate lol.

 

[Cali Dude]

The only JJ preamp tube that I have really loved is the e83cc. They are quiet and are not muted like some JJ ecc83s tubes. I'll have to check out the EH7025 next. I like their standard 12ax7s.

 

[TheMadStratter]

I've used long black plate Baldwin/Raytheons for years in my 5F2-A. Nothing dark about them. The perfect preamp tube for a tweed circuit.

 

[BlackStrat7]

I've used long black plate Baldwin/Raytheons for years in my 5F2-A. Nothing dark about them. The perfect preamp tube for a tweed circuit.

I can’t imagine a good one sounding bad in anything really lol. Have you tried the rca or Sylvania lbp in your tweed? That’d be an interesting tube roll.

 

[Green Craig]

@Green Craig Exactly what Baldwin branded Raytheon do you have? Are you sure it tests good? What was in there before?

I didn't know there was a difference in Baldwin-branded Raytheon tubes.

The Vox amp in question has one 12ax7, and the Ibanez in question has a 12ax7 and a 6L6. I bought two 12ax7's and a 6L6 as a matched set from Reverb...saved a few bucks by buying all 3 at once.

The OEM tube in the Vox was either a Ruby or an EHX, I don't remember and I threw it away because it was bad: got the amp for cheap, with the understanding that it didn't work; lots of crackling, had a hard time holding the right volume, all of which was solved when I put a new tube in. The OEM tubes in the Ibanez were either Ruby or Groove Tubes...again, I tossed 'em and don't remember specifically.

 

[BlackStrat7]

I didn't know there was a difference in Baldwin-branded Raytheon tubes.

The Vox amp in question has one 12ax7, and the Ibanez in question has a 12ax7 and a 6L6. I bought two 12ax7's and a 6L6 as a matched set from Reverb...saved a few bucks by buying all 3 at once.

The OEM tube in the Vox was either a Ruby or an EHX, I don't remember and I threw it away because it was bad: got the amp for cheap, with the understanding that it didn't work; lots of crackling, had a hard time holding the right volume, all of which was solved when I put a new tube in. The OEM tubes in the Ibanez were either Ruby or Groove Tubes...again, I tossed 'em and don't remember specifically.

They are the same. The difference is Baldwin, Lowrey, etc are supposed to have very tight tolerances. Some of the best of the batch if you will. Kinda how TAD or Ruby handpick the best for their select series hg series. Sounds like you got a good deal. Nothing better than buying a broken amp that only needed a tube change lol!

 

[tugboat]

The only JJ preamp tube that I have really loved is the e83cc. They are quiet and are not muted like some JJ ecc83s tubes. I'll have to check out the EH7025 next. I like their standard 12ax7s.

For kicks I got both the long plate ECC803S tubes and long plate ECC803S gold pin tubes from Eurotubes. The 803’s are not muted or dark. Great tubes. I find Eurotubes’ descriptions of the two spot on, the gold pin does sound different, smoother and a bit brighter. The regular pin version has more texture to it, in a Sticky Fingers or Exile on Main Street kinda vibe.

 

[Green Craig]

They are the same. The difference is Baldwin, Lowrey, etc are supposed to have very tight tolerances. Some of the best of the batch if you will. Kinda how TAD or Ruby handpick the best for their select series hg series. Sounds like you got a good deal. Nothing better than buying a broken amp that only needed a tube change lol!

Like I said, the original tube in the Vox (AD30-something-or-other, their digital modeller) was fizzy and crackly, got really loud, sounded distorted some of the time, and literally wouldn't play on a few of the models. I popped the new tube in and everything worked except for the fact that it now sounded dark, low, or actually out of tune which I attributed to the fact that it was a Raytheon/Baldwin tube and not the fact that it was now a completely functioning amp. The Ibanez is based on a Fender Champ circuit and had a little sparkle at the high end without being overbearing or shrill (with the original tubes), then with the Raytheon/Baldwins, also got darker or more muted. It plays nicer with the in-built Tube Screamer circuit for sure.