7 pro changes

[JeezyMcNuggles]

So, I made an interesting discovery the other day. I popped in one of these bad boys

And it turned my 7 pro into a crisp, clear, gainy, tight bottomed, rock machine

Popped the JJ back in today, and the fat, warm, massive 7 pro was right back at home.

Went back and forth a couple times, and then I realized, with this one little 25 dollar Mesa tube, I've just created an entirely new amplifier. One that's fat, warm, and round. And one that's tight, crisp, and clear with a more usuable breakup structure.

The stock JJ has more bass, and seems to be focused on the bottom end of the mid spectrum.

The Mesa has a tighter overall sound, with crisper highs, and seems to be very broad in the midrange.


With the turn of 10 screws (or so), I now have two completely different 1000w amplifiers.

Pretty nifty

 

[Doufuss]

OTOH, I owned a GK 550 Fusion class H amp and it actually sounded better with the stock JJ's. But I use these in my guitar amps almost universally in the V1 and they improve pretty much any amp. While being very crisp as you say, what the SPAX does really well is drop the noise floor way down.

 

[JeezyMcNuggles]

OTOH, I owned a GK 550 Fusion class H amp and it actually sounded better with the stock JJ's. But I use these in my guitar amps almost universally in the V1 and they improve pretty much any amp. While being very crisp as you say, what the SPAX does really well is drop the noise floor way down.

Yup. I notice a lot more hum with the jj in. Cool, I actually though I was trippin.

 

[seamonkey]

Don't miss the opportunity to record the difference so others can hear.
Loud and soft, maybe use a pre-recorded bass track to allow the different to be determined better.

 

[jmattbassplaya]

Tube rolling can be a fun pastime. I’ve always enjoyed the sound of Tung-Sols with their tight lows, full-bodied mids, and musical highs.

 

[frankie5string]

Is the stock tube an AU7 or also an AX7? They are different.
Somewhere around here I have two AX7-type tubes that are very different.

 

[A9X]

Putting heatshrink covering a good percentage of the envelope is a great way to shorten tube life.

 

[JeezyMcNuggles]

Is the stock tube an AU7 or also an AX7? They are different.
Somewhere around here I have two AX7-type tubes that are very different.

It's a jj 12ax7

And a Mesa 12ax7

 

[frankie5string]

It's a jj 12ax7

And a Mesa 12ax7

Maybe the JJ was just bad or damaged?

 

[JeezyMcNuggles]

Putting heatshrink covering a good percentage of the envelope is a great way to shorten tube life.

Yeah, I'm sure nobody knows what they're doing over at Mesa engineering. Or, the countless companies that make tube microphonic dampeners just like that, for the same purpose.

 

[JeezyMcNuggles]

Maybe the JJ was just bad or damaged?

No. It's not. That's how they sound.

 

[JeezyMcNuggles]

Tube rolling can be a fun pastime. I’ve always enjoyed the sound of Tung-Sols with their tight lows, full-bodied mids, and musical highs.

I just ordered an electro-harmonix to try out too. Maybe I'll get a tung sol too, and make a shoot out video.

 

[frankie5string]

No. It's not. That's how they sound.

That's weird. The SPAx7 is a Mesa QC'ed tube from any number of makers... it's supposed to be lower noise, but not drastically different sounding form any other good 12AX7 tube. They are very well regarded, though. I'd use them more often if they were available when I needed some.

The JJs I have are all punchy and clear in their installs, even when run low.
Maybe @agedhorse can explain why the Mesa is so sonically different in this case?

 

[JeezyMcNuggles]

Tube rolling can be a fun pastime. I’ve always enjoyed the sound of Tung-Sols with their tight lows, full-bodied mids, and musical highs.

Ordered

 

[JeezyMcNuggles]

That's weird. The SPAx7 is a Mesa QC'ed tube from any number of makers... it's supposed to be lower noise, but not drastically different sounding form any other good 12AX7 tube.

The JJs I have are all punchy and clear in their installs, even when run low.

It's a Mesa 12ax7. The same tube that is in every one of thier guitar and bass amps. Every tube, from every maker, is different. And, they all sound different in every amplifier. Current, pre amp, hardware, etc. This 7 pro sounds no different than my last one. And, any tube I roll in or out of it, will change its tone.

The stock "premium" JJ, is fat and warm. The Mesa is crisp and clear.

I've got a couple more coming. I'm hoping I find one that's in between these two. That one will be the winner.

Right now, with these two tubes, the differences are so drastic that it sounds like two different amps altogether.

 

[frankie5string]

It's a Mesa 12ax7.

I hear ya... How do you know that Mesa tube isn't a JJ? They do acquire tubes from JJ.
There aren't THAT many tube manufacturers left.

 

[Doufuss]

I hear ya... How do you know that Mesa tube isn't a JJ? They do acquire tubes from JJ.
There aren't THAT many tube manufacturers left.

We don't. Or at least, I don't.

From Mesa -

"MESA® SPAX7 preamp tubes are a premium grade 12AX7 that possess an even higher standard of overall performance due to their incredibly low sensitivity to microphonic noise. This is the ultimate preamp tube to use in critical gain stage applications, particularly in first stage/input positions or other high gain stages in the preamp tube string. These tubes are selected during our rigorous 12AX7 testing process and when found to be substantially more stable and quiet in extreme high gain applications, they are fitted with a shrink-wrap shielding, further stabilizing the tube and reducing external interference and noise. MESA SPAX7s deliver the lowest noise floor for the highest gain output. While not required for optimum performance, SPAX7s are a great tube to have on hand as spares and for any applications where the absolute lowest noise floor and low-microphonic response is needed."

In my personal experience, these tubes are what they say.

 

[A9X]

tube microphonic dampeners

Not the same thing and they cover significantly less of the envelope usually.

 

[JeezyMcNuggles]

We don't. Or at least, I don't.

From Mesa -

"MESA® SPAX7 preamp tubes are a premium grade 12AX7 that possess an even higher standard of overall performance due to their incredibly low sensitivity to microphonic noise. This is the ultimate preamp tube to use in critical gain stage applications, particularly in first stage/input positions or other high gain stages in the preamp tube string. These tubes are selected during our rigorous 12AX7 testing process and when found to be substantially more stable and quiet in extreme high gain applications, they are fitted with a shrink-wrap shielding, further stabilizing the tube and reducing external interference and noise. MESA SPAX7s deliver the lowest noise floor for the highest gain output. While not required for optimum performance, SPAX7s are a great tube to have on hand as spares and for any applications where the absolute lowest noise floor and low-microphonic response is needed."

In my personal experience, these tubes are what they say.

Mine too now

 

[JeezyMcNuggles]

I hear ya... How do you know that Mesa tube isn't a JJ? They do acquire tubes from JJ.
There aren't THAT many tube manufacturers left.

JJ could very well be their tube supplier. Built to their specs. The SP, would then be the "creams of the crop" seeing as how they are the same tube as mesa's standard 12ax7. Just put to higher testing standards, and shrink wrapped.

Who knows, who cares? The two tubes are built, and sound, completely different regardless.