I have joined the Dark Side (well not really)

[KJung]

Sure thing. If they were like my stock Mesa's, you'll notice a difference immediately. The Mesa's were thin, much quicker breakup and cardboard sounding in comparison. The Tung-Sols open everything thing up. They gave me more headroom, the break up is much smoother and they are warmer and definitely provide more musical detail. You definitely have the knowlege and ear to make it worth your while. Good luck.

They are on the way! Thanks!

 

[Psycho Bass Guy]

Because I'm a moron:
which position is that, and does that effect channel one, two, or both?

The driver tube is the one furthest to the left when facing the front of the amp, behind the power and standby switches. The change drops the gain of the overall output of the amp after both channels.

It'd be in the same place on my 400, right?
My 400 has an all JJ tube compliment in it currently...

I don't know for sure, but I'd imagine so. It won't hurt anything to try it in any of the preamp positions.

As long as I run "input lower/master higher" my 400 stays relatively clean, as long as I'm not pushing a really jacked up active G&L with massively high output thru it...My G&L El Toro especially will push it into the crunch zone pretty quickly.

That swap may help you.

Alright now you've got me curious - which SS amps do you like? Inquiring minds want to know.

I wasn't talking about bass amps. My favorite solid state bass amps are still in production. I'm talking about good old lead-sled power amps, like Crown Microtechs and QSC MX's.

 

[pedro]

Oh. (Pedro somewhat disappointed.)

 

[Psycho Bass Guy]

If it's any consolation, I dig GK's and old Gibson Lab amps.

 

[pedro]

(Pedro perks up.)

 

[Chef]

Thx mang

The driver tube is the one furthest to the left when facing the front of the amp, behind the power and standby switches. The change drops the gain of the overall output of the amp after both channels.



I don't know for sure, but I'd imagine so. It won't hurt anything to try it in any of the preamp positions.



That swap may help you.



I wasn't talking about bass amps. My favorite solid state bass amps are still in production. I'm talking about good old lead-sled power amps, like Crown Microtechs and QSC MX's.

 

[mgmadian]

I've had some time to play with it. I swapped the driver 12AX7 for an old Tungsol 12AU7 I had laying around. That tamed alot of the gain and gave a bigger bottom to boot. I basically got headroom by sacrificing gain and the larger current capability of the 12AU7 means that the drive section won't clip on lows as easily. Swapping the 12AU7 in the first stage gave a more subdued tone, but the power section didn't have as much booty and the EQ didn't work right. Swapping the drive tube cleaned up the amp's tone considerably without messing with the tone stack. As a bonus, when I removed the amp's cover, I found a loose GT12AX7 inside. It's a Chinese cheapie, but it was a freebie!

Very good to know, I'll have to try that out. Wonder how a 5751 would work here. I recall swapping a Sovtek 5751 in to my former Kern preamp (which came with 12AX7s) and hearing (and liking) changes similar to what you describe above -- lower gain but clearer / cleaner.

... or a Philips 5814, which I use in place of a 12AU7 in a tube compressor pedal, with good results.

 

[rok51]

With the thread title, I thought you were going to say you bought a solid-state amp!

Asad

Me, too! Whew!

Kim

 

[Psycho Bass Guy]

Very good to know, I'll have to try that out. Wonder how a 5751 would work here. I recall swapping a Sovtek 5751 in to my former Kern preamp (which came with 12AX7s) and hearing (and liking) changes similar to what you describe above -- lower gain but clearer / cleaner.

... or a Philips 5814, which I use in place of a 12AU7 in a tube compressor pedal, with good results.

A 12AU7 has significantly lower gain than a 12AX7, but more importantly, handles a much larger amount of plate current. Since the driver stage isn't as input impedance sensitive as a preamp gain stage, the gain factor and current headroom make the amp quieter and cleaner. The reason the tone controls didn't work right when the 12AU7 was subbed for the frist 12AX7 was because the plate impedance of the 12AU7 wasn't high enough to properly load the RC network of the tone stack. I expected it, but in some amps the change is positive.

I wouldn't expect a 5751 to be as dramatic a change, but the bonus is that it could be subbed in the first preamp gain stage and not screw up the tone controls.

 

[bucephylus]

Quick question... I have a Mesa MPulse600 that I like very much. I am clueless about different tubes. I have the stock 'Mesa' tubes (two 12ax7's I believe). If I wanted to swap them out for a smoother, deeper, cleaner tone, what 'brand' or model of 12ax7 would you suggest. I'm not sure I really need to do this, since that amp sounds smoking, and I actually bought it for those situations where I enjoy a little more 'grit and dirt' in my tone, but it might be fun to do a swap and hear the difference, if any.

Thanks... K

Edit: Sorry for the OT post.

Hi Ken,

I have found the information on this site to be fairly useful regarding preamp tubes:

http://www.audioasylum.com/audio/faq/joes-tubes.html

I've liked several of the better 5751's I've been able to acquire.

 

[basey]

Tung Sol New Production 12X7s!

http://www.tubedepot.com/ts-12ax7.html

I spent about 4 weeks researching 12AX7s to replace the stock Mesa tubes in my 400+. Tung Sol's gave me everything I was looking for and everything you mentioned KJung. I also tried a Electro Harmonix 12AX7s and they were good too, but I ended up feeling better about the Tung Sols. The stock Mesa's were really bad. I think they were rebranded Sovtek WA's 12AX7s if I remember correctly. The difference was night and day. Were the Tung Sol's twice as good as the Electro Harmonix, given the price? Probably not. I would say the Tung Sol's gave me a little more clean headroom and seemed to be a little more warm and musical sounding. The EH's gave me a little more gain.

+1
and sovtek wxt+'s
Believe me, I've tried all the new issue tubes in it. Thats the best combo without going to NOS tubes IMO.

 

[KJung]

Hi Ken,

I have found the information on this site to be fairly useful regarding preamp tubes:

http://www.audioasylum.com/audio/faq/joes-tubes.html

I've liked several of the better 5751's I've been able to acquire.

Thanks!

 

[GreyBeard]

Psycho;

It's good to read that you having so much fun.

 

[anderbass]

I do intend to put it on the 'scope and install bias adjustment controls

How many adjustment pots are ya thinkin?

 

[Bob Moulton]

+1
and sovtek wxt+'s
Believe me, I've tried all the new issue tubes in it. Thats the best combo without going to NOS tubes IMO.

Sovtek WXT+ are 6L6's. That's what I have in the power section of my 400+. KJung's question was about 12AX7's. Maybe I am missing something here?

 

[basey]

Sovtek WXT+ are 6L6's. That's what I have in the power section of my 400+. KJung's question was about 12AX7's. Maybe I am missing something here?

I was agreeing with your statement on the tung sols and adding that using them in conjunction with the wxt+'s was the best combination (after several retubes) that I've found to get a more defined sound. Which is what I thought he and Psycho Bass Guy were after. I guess I should have explained what I meant a little better in the post.

 

[Bob Moulton]

I was agreeing with your statement on the tung sols and adding that using them in conjunction with the wxt+'s was the best combination (after several retubes) that I've found to get a more defined sound. Which is what I thought he and Psycho Bass Guy were after. I guess I should have explained what I meant a little better in the post.

Gotcha, makes sense now. Sorry, it's 11:00am and I still haven't left my office for coffee yet. This seems like as good a time as any.

 

[Big String]

Hey Psycho.. good to hear from you.
I miss my 400+'s nice amps. Been around a long time.

I was really happy with Sovtek 6L6GC and the EV pre's in mine. Made it really ballsy and clean/punchy but easy to overdrive if desired. You knew that...

 

[Psycho Bass Guy]

I was agreeing with your statement on the tung sols and adding that using them in conjunction with the wxt+'s was the best combination (after several retubes) that I've found to get a more defined sound. Which is what I thought he and Psycho Bass Guy were after. I guess I should have explained what I meant a little better in the post.

The Tungsol 12AU7 I'm using is an OLD US made Tungsol from way back in the day. I'm still planning on doing some more preamp tube swaps. There's some weird high-mid/high-end resonance in the tone that I'm not liking. It's not exactly microphony, at least not like I've ever heard before. I have heard of JJ preamp tubes doing that, (the amp came with a full set of JJ preamp and power tubes) but have never experienced it until now. I'll probably try an RCA 5751 for the first preamp stage and see what that does for me.

The power section sounds killer; running my bass into the effects return sounds killer, but after I tamed the gain of the amp it's not really viable to use that way and I hate bypassing that fun-to-play-with preamp. I'll install dual bias controls one day, too.

 

[Rickenbackerman]

Oh crap, Psycho done went and bought a Messy-Booger!

Are you planning on trying it out in a band situation? I'll be curious to see if you think it gets lost in the mix as compared to an SVT. That's basically why I dumped mine - not enough mids without having to 'frown' the EQ, and then things start to get strange as far as gain and this weird upper-mid "honk" that I never could dial out. Although I never did try the 12AU7 swap, I did try a few tonestack mods with slightly improved results...
I guess I just got tired of spending too much time playing around with the damn thing and never really getting it to sound as good as just plugging into an SVT with the tone controls flat and cranking it to 11:00 or so.