12AT7 vs 12AX7

[rrguitars]

Hey, anybody try replacing 12AX7s with 12AT7s in their TC? I read that John Petrucci swears by placing a 12AT7 in V1 in the Boogies he's used (if I remember that correctly). Well, I replaced V1 with a Groove Tube 12AT7 and it provides a more focused, less hairy distortion but drives really nicely. Cleans up your solos and tightens up your rhythms but really responsive. Clean channel feels great, too. I'm also using Mesa STR445 6L6s (Duet - TR-50) for a tighter sound typically used in their Rectifiers. https://mesaboogie.com/tubes/power-tubes/6l6-str-445.html
Channels are always in Clean - Tight - Tight mode.
I plan to experiment further with the 12AT7 but I was curious if anyone else has tried this or has more info.
Thanks.

 

[Nerd]

Substituting 12AT7 in place of 12AX7 never worked well for me but I other people had good results by doing this

 

[user 21540]

People do sub 12AT7s for 12Ax7s and it will generally speaking 'work' but ATs (like 12AU7s) are used more as driver type tubes -- such as in the reverb sections of guitar amps. Most descriptions about preamp tubes only mention gain factors but 5751s, 7025s and 12AY7s are all better subs for 12AX7s as there are electrical differences between AT7s/AU7s and AX7s.

You can look into this yourself though and make your own judgement:
https://www.thegearpage.net/board/index.php?threads/i-read-an-article-that-7025-12ax7-12at7-and-12au7-tubes-are-interchangable-i-had-no-idea.2275657/
https://www.audiocircle.com/index.php?topic=98231.0
https://www.thegearpage.net/board/index.php?threads/swapping-12ax7-for-12at7.1444343/

 

[rrguitars]

Thanks for the response! After reading up on your suggestions I ordered a special JJ 5751 from Eurotubes. Looking forward to dropping it in once I get it this Friday. I'm hoping to get similar to better results in my Blue and Red channels but really hoping my Green channel gets a boost. The volume in my Green channel is really suffering. My Blue and Red channels sound much tighter/articulate and less hairy with a decent touch response and less noise with good aggression. Blue and Red also appear to be more consistent from low to high volumes. High volume is a real pleasure now. For me It's been a world of difference and everything would be great if the Green channel volume wasn't suffering. I would have to say my point of reference would be something similar to the clear and articulate touch response you can hear from guitarist Ronni Le Tekrø (TNT - specifically the Tuition album) but with that Grrr! I'm getting from the TC-50. I'm just looking to move the amp towards that direction and the 12AT7 has helped that.

 

[user 21540]

Oh cool. I haven't tried the JJ 5751 -- let us know how it goes.

Cheers,
Canaan

 

[rrguitars]

Well, in a nutshell, not good. The 5751 is weak and fuzzy. I like how the 12AT7 tightens up the distortion in V2 and still drives the blue and red channel but the green channel's volume really suffers. So, recently I'm back to all 12AX7's. I'll try some experimenting again another time.

 

[user 21540]

Hey man -- sorry it didn't work out. You might find another use for the tube some other time though. JJs generally are a bit hit and miss for some people too. People often describe darkness or fizz and not much in between. I have had verified fully tested ones from Eurotubes fail in short time on me too. Nearly all the Mesas are made to run on all 12AX7s -- so those are all in spec. I also find most Mesas I have played are a compromise across the various modes and channels in some way. In fact I think all channel switchers are.

 

[jnoel64]

In the TC series, V1 is the 1st and second gain stage for the clean channel. That's why your clean volume suffered. V2 is the third gain stage for the clean channel. Try your other variants in V3 or V4. It may sound better....or not.