SPAX7 vs 12AX7 (and the 12AT7) for Roadster Head Re-tubing

[kyldh]

Hello all. The age old question... What tubes are going to make my equipment sound the best? I know this is a tough one since we all have different tastes, but I specifically wondered if anyone had some input on the Mesa SPAX7?

I have a Roadster head.

Over the years with different Mesa heads, I've always just played it safe and gotten the Mesa tubes. I always loved the way they sounded and figured "Why mess with a good thing?!"

Of the SPAX7, Mesa says "This is the ultimate preamp tube to use in all critical gain stage positions." So would I best off just using the regular 12AX7 for most of my replacements, and trying this guy in V3 for my Gain on Channels 3 and 4?

Also, Mesa's site mentions that the 12AT7 is used on the reverb position for many older Mesa amps. Would it help or hinder a Roadster to use a 12AT7 in V4 for the reverb?

Any other tube recommendations that I should not overlook?

Just to note... I like my cleans to be crystal-clear, and my gains to be extremely heavy... in case that effects anyone's recommendation.

 

[jbird]

I've been told , and used the spax7 in v1, and if you've noticed, many on this sight swear by the tung sol in v1!

 

[kyldh]

I've been told , and used the spax7 in v1, and if you've noticed, many on this sight swear by the tung sol in v1!

And what did you feel like you gained from either of those? Brighter tone? More gain? I wouldn't want to use anything that would make my clean channel break up sooner. I like as much headroom as possible.

I guess if a SPAX7 is actually going to improve my tone then great, I'll try it out. But I wasn't sure what a "critical gain stage" really meant or in what way it was truly meant to impact my tone.

 

[MrMarkIII]

The SPAX7 is cherry-picked from Mesa's batch of tubes for LOW NOISE.
Nothing whatsoever to do with "tone" or "gain".
Low noise characteristics ONLY.
Mesa recommends use in the first 12AX7 position, usually V1.

 

[kyldh]

Ohhh ok. That makes sense then. Thanks

 

[Chester]

A Tung Sol in V1 brightens tone. Cleans are cleaner than with Mesa or JJ's in my experience

I have the following (all 12 AX7) for a lively and crisp response / full and detailed distortion

V1 - Tung Sol (balanced)
V3 / 5 - Mesa standrad (cathode follower positions)
Others - GT 12AX7-M (balanced in PI position)

Power amp: TAD 6L6 STR RCA (Mesa biased) for a similar response to =C= 's

 

[TRENCHLORD]

I'd also suggest trying an EH in the V1.
Mesa used to always use these "Russian #2" 12ax7 in the non-cathode follower slots.

Not sure why they quit using them, maybe they want all the preamp tubes to be inter-swappable?
Their current rebranded jj's aren't picky about the slot positions.
In my limited experience the "Russian#2" is a bit more gainy and gritty which I love.

The single-rec is an excellent tester since you don't have to remove any other tubes to swap the V1.
I'm getting ready to order a couple tungs and a couple of the Russians, and I already have some spax7s.
Will report back after some more swapping.

 

[LithiumZero]

V1 - Tung Sol (balanced)
V3 / 5 - Mesa standrad (cathode follower positions)
Others - GT 12AX7-M (balanced in PI position)

Power amp: TAD 6L6 STR RCA (Mesa biased) for a similar response to =C= 's


^ This! Also I prefer the TAD 6l6 in my roadster over the winged C. The TS in V1 really made a huge improvement

 

[TRENCHLORD]

After some back and forth in the single-recto and in a rev-G Dual.

The tung-sols took me in the wrong direction with both amps. I tried two different Tungs in the V1 position only, and just found them too smoothing.
They were punchy in the midrange but lacked that ratty presence and cleaner low-end that I guess I prefer.

EH (Russian#2) was perfect for the Dual. I liked it just a bit better than the spax7. Seemed a bit brighter in the treble and it felt like it had more gain, but everything else was actually fairly close.
This is my first two-channel dual, and even though it's a rev-G it still sounds a bit warmer/darker than the newer models, so maybe that's why I liked the little extra fizz/zing of the EH.

Spax7 won out in my single. The lows feel just a hair tighter than the Russian#2, and the top-end has a little less fizz, both qualities were a help in the single.


Just for reference; I use emg81 in most, and also a x2n in another guitar.
Different pickups and NOT running an 808 might well yield me different preferences, but I only care what works for my own setup of course.

 

[kyldh]

For what it's worth, I just thought I'd post this update real quick... I had an important gig coming up and my Roadster had a tube die on me. It still had the same tubes in it from when I bought it used, so I just decided to replace them all... that way I knew they were all 100% "good to go." I called Sweetwater because of their free shipping and placed my order... all Mesa-branded tubes (I like 'em, so sue me. :wink: ) Turns out though, that they were out of 12AX7... bummer! I asked "Well, could you upgrade me to SPAX7 at the same price then?" They said they wanted to, but couldn't because the Mesa pricing is strict and they're not allowed to discount their stuff. They did offer me a free upgrade to overnight shipping though, so I took the plunge to try out the SPAX7.

Now... everything I've heard, both on this very thread and when calling Mesa, told me that the SPAX7 is recommended for V1 because of it's low-noise. Otherwise, it's supposed to be the exact same as the other 12AX7s from Mesa. So... I put it in EVERY position except for the effects loop :lol: (i left the old 12AX7 in because I don't use the loop anyhow)... Waste of money spending the extra $4 per tube? maybe... but this what I noticed for anyone who might be curious:

SPAX7 certainly is low-noise... compared to my old tubes at least, and I have no idea how old they were. They were Mesa-branded Russian-2. Not that the old tubes were LOUD by any means... but you can seem to tell that these are noticeably less noisy I suppose.

SPAX7 is very similar in tone... which makes 100% sense since they're supposedly just the "pick of the litter" of the same 12AX7s you'd be buying from Mesa otherwise. HOWEVER, for some reason my channel 4 sounds more "shrill" now almost. I use this channel on "modern" for that high-gain modern recto sound, and I feel like there's just more high end for some reason now. Other channels weren't really impacted in as much of a noticeable way. I'm sure I can mess with the EQ and dial in a great tone again though... not really worried there.

Would I buy SPAX7 again? Yeah probably, but only for the V1 position in the future I imagine. Outfitting the whole thing with SPAX7s looks like it's going to be a one time thing. Glad I tried it though. Now I know!

I'm still interested in trying some different tube brands, but I'll wait until I have more disposable income since tubes aren't generally returnable. I tried some different tubes in my Triple Rectifier years ago and just hated how they sounded. (I can't remember what tubes at this point.) They all became "spares" and I bought a new set from Mesa. That kind of trial and error gets very expensive. haha.

 

[bandit2013]

I do not have a Roadster yet, still waiting for it to come in. I do have three other Mesa amps that are not related to the Roadster, Mark V, RA100 and Mark IV. I have, however, experimented with many different tube brands with all of my amps thus far. I do like the Tung Sol in the gain circuits for the RA100. The Mark IV sounded the best fully loaded with TS, it sounds almost as good with the Mesa branded JJ tubes. The Mark V on the other hand, that is a long story. So far what seems to take away the brittleness and yet provide a tight low end with plenty of grit in the gain structure is the Mullard Reissue 12AX7 (not grainy or too compressed, really wakes up the 6L6GC at full power). On the clean channel, it is nice and articulate. I did not get the same response with those in the RA100 on the clean channel circuit (RA has two separate preamp circuits for gain and clean and is not cascaded like the Mark series amps). When I get my Roadster (been a long wait) I can probably chime in on more accurate details on what tubes do what ( if I like the OEM tubes I may not change anything). In the past, I found the SPAX7 to be more prone to feedback. The time I had used them was with my Mark III. which came equipped one of the SPAX7. At that time, Mesa was using the Shuguang tubes (has the square getter and the clips over the plates ). I still have a few of them that are in good condition and have used them with great results in both the RA100 and Mark V. So much for writing a lot without saying anything.

 

[Given To Fly]

I have all SPAX7's now. They definitely run quieter. I scared the heck out of myself by playing a big 8 string power chord really hard because I thought my volume knob was rolled off, nope, it was all the way on... :shock: I think it was worth the extra money just to find out if there was a difference. Overall, I do not think it will make or break an amp though.

 

[kyldh]

I scared the heck out of myself by playing a big 8 string power chord really hard because I thought my volume knob was rolled off, nope, it was all the way on... :shock:

:lol: I've done the same thing a few times now.

It could be useful when recording. For the most part though, I'm also glad I tried it but didn't think it was too groundbreaking of a change. Perhaps I'll keep a set around just for recording and swap them out with regular 12AX7s the rest of the time.

 

[bandit2013]

I finally got the Roadster, this is the First amp I do not want to tube roll with since I sounds incredible as it is.