12AX7 Tubes

12AX7's are all pretty similar in terms of the amount they clip (crunch). Also, they are the highest-gain tube in the immediate family that can be swapped in, so you have nowhere to go but down (less crunch).

Swapping tubes may get you slightly different flavors of distortion, subtle qualitative differences, but if you need more than it's giving you already, you need an external distortion pedal.

 

There are some sites like that, and several threads here talking about X tube has creamier mids and Y tube has tighter lows, but IMO they are not useful unless you have the exact same amp as the person talking. Each amp/preamp will have its own different design (the amount of voltage going to each of the tube's internal parts, for example) so they will all have slightly different response to/with different tubes. And some amps/preamps are designed so there won't even be any change when swapping tubes! The Bassman should respond to changes, but again you'll want to hear only from other Bassman owners. Or instead, just get a few different tubes and try them out. It's money, sure, but that's the best way to find what'll actually sound best.

 

JJ 12AX7's have a lot of gain.
Electro Harmonix is about 8 of 10 compared to the JJ's gain, but IMO have a much more harmoniclly filled tone, with an upper mid punch and responsivness that I have yet to find in ANY other tube I've rolled (and I've rolled alot).

 

Or maybe an amp mod. I've never worked on a 100T though, so as usual, I know nothing...

 

I have found the same thing. I like the Electro Harmonix.

 

Modern day tubes are cheap. Buy 3 or 4 different brands and see what you hear/feel.
Best

 

Maybe try a 7025. Still high gain, low noise. Maybe an ECC83, too.

 

I hear differences in tubes to be so subtle that they're pretty much imperceptible to my ears. I'd leave it alone but some people like to change out tubes and say they hear differences, so what do I know?

 

or a linear booster...if you want to drive harder the first tube gain stage...retaining the native character of the tone.
A distortion pedal can fit the bill, but sometimes adds its own flavour. Just a matter of taste.

 

I thought the same about the differences in different makes, BUT I changed a Groove Tubes for an EH and the difference was amazing - much more top end and definition.
I suspect that the Grooves Tubes was a dud, but even if this is the case, it would still pay you to change your current tube out in case it's gone the same way.
They are cheap, unless you go for a NOS Mullard which has been lovingly stored in a WW2 oak case for the past forty years etc etc.
It's worth a go!

 

I found that changing the 12ax7s in my ampeg cl preamp had very little affect but when I changed the 12ax7 in the power tube driver stage things were alot more noticeable!

 

I've put a Telefunken ECC83 in my Shuttle 9.0. I can't hear a difference, but Doug Parent can. Now, I put an identical tube in V1 of my DB750, and it made a very noticeable difference - tighter bass. However, I put a Siemens 12AU7 in V4 and it didn't make an iota of difference. So I think some amps respond differently to tube rolling from others. I did a little tube rolling in my WT-800, and didn't notice any difference in sound.

All this from a guy who definitely lacks "the golden ear."

 

I don't think you'll see the extra crunch your looking for out of a tube swap. You might really like the effect of a clean boost pedal to your input stage. If money is an issue you can buy a ART Tube MP preamp and use it like a clean boost to overdrive your preamp stage. You won't be able to just click it off like a pedal but they can be found very cheap. They sound great as well.

If your wallet allows it, Creation Audio has a very nice clean boost as does Fulltone and a bunch of others.

 

If you don't believe tubes make a difference talk to HiTest Tubes.

Putting a 12 ax7 in phase inverter will give you more gain. getting luck or spluring for a balanced 12at7 in the same spot will get you more bass. A great tube for this is the CV4024 from Mullard. All over the place and usually less than 30 bucks.

Change the order of the tubes. It's free and can make a difference. To make your life much easier watch the orientation of the open spot on the pins. Putting the new tube back in the same very carefully so as not to bend the pins is good. If you're going to get into this get a pin strightener.

Here's a link to a little more detail.

12AX7 Tube Type Review

But Aspen Pittmans tube amp book and buy a grain of salt to go with it. Lot's of good stuff but a little snake oil.. The JAN Sylvanias are cheap and provide a great bright v1.

 

...Talk to a company that sells vintage tubes... Yeah that will get you an honest, unbiased view.

 

A big +1 for the Tube MP. It does what it does very well, and it can do much. I sometimes use mine as a clean boost, or sometimes, overdrive the unit itself for a very filthy distorted tone.....but what I generally do is run the unit to the point where the LED just barely indicates clipping on the attack of a note. That seems to dial in a bit of subtle compression, with leaving enough "hair" in the sound for me to be pleased. It does introduce a small bit of noise, but I've heard that can be remedied in some way.

 

Bongo you might not believe it but I've talked to people who said that Gregg has spent hours with them getting their amp voiced in a way they loved. He isn't cheap, as in inexpesnive but he knows tubes.

Spend some time rolling a few. I got a UniValve so i can afford to listen to glass at a bargin. Not a bass amp, although I've played bass through it. I may not be able to play guitar but I have some great sounding amps. And a lot of it is spending the time to get the right tubes at the right spot.

The audio guys have been doing this for decades. Check and see what a set of NU 300s go for.

Steve at Angela had some 6l6 jan NOS for $200 a set. I don't know if that's current but if you have over a thousand hour on the Bassman100t outputs you will notice a difference when you put these in and bias it.

BTW output tubes generally need to get biased. Bias meters pop up on the bay every week or so.