Can an amp’s tone change if...

[RoketRdr]

I remember reading something back in the day about the way the tubes would vibrate a little in combo amps- as in, components in the tubes were vibrating relative to each other, etc. It seems like it would lead to pretty serious tube failures if they were really being shaken that hard, but who the heck knows.
Really interesting observations @York Audio ! Looking forward to seeing this thread continue!

Agedhorse on TalkBass forum is the Mesa bass amp and cab designer for many years. He's discussed this phenomenon and that's exactly what he said. The tubes pick up vibrations and sound resonance and it changes the tone depending on how/where the amp is mounted. He said it doesn't harm the tubes or shorten their life, else they would've never been used in fighter aircraft, but it does change how you have to tweak the amp based on where its mounted and how its used. The gist of what he said on the tone was that the same tones are still there it will just require a little tweaking.

 

[yek]

Can an amp’s tone change if it’s in a head box or a combo?

According to Cliff: yes. Because it's the raison d'etre for the parameter PREAMP SAG.

"Turning this ON causes the amp block to behave like an integrated tube head or combo amp. Turning this OFF simulates a separate preamp and power amp."

 

[unix-guy]

According to Cliff: yes. Because it's the raison d'etre for the parameter PREAMP SAG.

"Turning this ON causes the amp block to behave like an integrated tube head or combo amp. Turning this OFF simulates a separate preamp and power amp."

That's talking about having separate Preamp and Poweramp...

Justin is talking about the whole Amp being just inside a head cabinet or inside a combo cabinet. It's the same "integrated" pre/power amp in both cases

 

[Adman103]

Agedhorse on TalkBass forum is the Mesa bass amp and cab designer for many years. He's discussed this phenomenon and that's exactly what he said. The tubes pick up vibrations and sound resonance and it changes the tone depending on how/where the amp is mounted. He said it doesn't harm the tubes or shorten their life, else they would've never been used in fighter aircraft, but it does change how you have to tweak the amp based on where its mounted and how its used. The gist of what he said on the tone was that the same tones are still there it will just require a little tweaking.

No kidding! Wow, that's interesting to hear! I think I remember reading something about it in the old Dave Hunter amp book. I'll have to dig that out again and try to find it.

On a somewhat related note, it's bizarre to think of vacuum tubes being used in jet fighters. I mean, at that point in the march of technology, you have to use it, but little glass tubes...

 

[RoketRdr]

No kidding! Wow, that's interesting to hear! I think I remember reading something about it in the old Dave Hunter amp book. I'll have to dig that out again and try to find it.

On a somewhat related note, it's bizarre to think of vacuum tubes being used in jet fighters. I mean, at that point in the march of technology, you have to use it, but little glass tubes...

Agedhorse has been in the industry for over 40 years designing amps and cabs. When he begins posting technical responses on the forums I eat it up because the guy has forgotten more about amp/cab design than most of us ever learned.

The original fighter jets and a few others up until the 60's had tubes in them. Not the case since the late 60's.

 

[reclavea]

It always amazed me why my Mesa Simul-Class Mark III fully loaded head with a 2x12 vertical cab always sounded incredible compared to it’s combo counter parts!

extra, extra, EXTRA mojo for sure!

 

[shatteredsquare]

well if you can change preamp response a lot just from removing some metal covers from the preamp tubes, i can't imagine how much interference would be made by having two big ass magnets sitting 6 inches below the preamp tubes, like what a neck pickup does to guitar tone, really close to the strings and it's like a magnetic dampener (makin harmonics come out of the strings), lower it down and it opens up the tone, take it out completely and the guitar never sounded so good.