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400 Tube watts into 2x AMPEG pf115

Fab Savage

Fab Savage

Oct 27, 2009
199
11
Perth, Australia
#1
Hi All

Had a quick flick through the PF115 threads, and am interested if you think that two of these sweet cabs would handle my Marshall VBA 400 pushed reasonably hard? (say 2o'clock)

I already have one PF115 at home and love it as a 'practice' cab with about 40-50 tube watts into it. So I wondered whether adding another one for my bigger rig might work...just into terms of mechanical/thermal damage/speaker distortion. I am sure they would sound great...at least up to a point.

Cheers
 
#3
It should be able to take it to a degree...I've used my PF115he's with an SVT and gotten pretty screaming loud with it. However, I wouldn't be turning it up to 10. I would only turn it up to the point where the distortion sounds good and absolutely no more than that. Past the 400w and you've got at least 400w more available as peak power, and the absolute thermal limit on two of those cabs would be 800w, so while you can push them, you can also push them too far.

Honestly, I'd be just as tempted to use the 50w amp you have for both cabs as the VB400. I've used my B-15 with them before, and it's a thing of beauty and won't blow a PA out.
 
#8
BassmanPaul said:
There are no such thing as tube watts! Watts is watts no matter how derived. :)
Click to expand...

This is true. Watts IS Watts, but tube amps are generally rated for their clean power, before distortion. Once you push them into overdrive, they put out quite a lot more power. Hence the feeling that "tube watts are louder".

Cheers!
:bassist::bassist::bassist:
 
#9
Roadkill said:
You've obviously not fully experienced a cranked bass tube amp :smug:. About 2x as loud I'd say :cool:.
Click to expand...

LOL I have been playing bass for fifty years and building tube amps for about forty five. Yes I have had the misfortune to play through a "fully cranked tube amp", there was no other way to get enough volume, and hated it. I want my bass to sound like a bass and not a badly distorted guitar.

Watts are still watts and at the same measure of distortion are equal between tubes and SS.
 
#10
Clammy said:
This is true. Watts IS Watts, but tube amps are generally rated for their clean power, before distortion. Once you push them into overdrive, they put out quite a lot more power. Hence the feeling that "tube watts are louder".

Cheers!
:bassist::bassist::bassist:
Click to expand...

A properly spec'd amplifier is its power before the onset of clipping. That goes equally for both SS and tube. Both can give more when clipping. Tubes tend to sound more pleasing to the ear is all.
 
#11
BassmanPaul said:
A properly spec'd amplifier is its power before the onset of clipping. That goes equally for both SS and tube. Both can give more when clipping. Tubes tend to sound more pleasing to the ear is all.
Click to expand...

Yes, that's what I said. However, my experience has been that SS amps are generally clean until almost full volume, whereas tube amps tend to get into clipping earlier on, and then produce a ton more power. I've used 100W Marshall Super Bass heads live without problem, but any SS amp I've had to use that was rated under 300w was wholly inadequate.

Tube amps definitely sound better when pushed into distortion. Most SS amps sound like thinned out ass when they get into that territory.

Cheers!
:bassist::bassist::bassist:
 
#12
Clammy you are describing something more akin to gain structure rather than power. For myself, I feel that a SS power section is a more elegant way of converting electricity into audio power. That said I do like to have tubes in my signal chain. My pre-amp is fully tube, you can see it in the tube guts thread, but it feeds a Class D power amp.

Much as I love tube amps I'll not gig with one again. All the amps I design are guitar amps (shhhh Paul - it's a bass forum! ). :D
 
#13
BassmanPaul said:
Clammy you are describing something more akin to gain structure rather than power. For myself, I feel that a SS power section is a more elegant way of converting electricity into audio power. That said I do like to have tubes in my signal chain. My pre-amp is fully tube, you can see it in the tube guts thread, but it feeds a Class D power amp.

Much as I love tube amps I'll not gig with one again. All the amps I design are guitar amps (shhhh Paul - it's a bass forum! ). :D
Click to expand...

It may be the gain structure, but it still gives the impression that "tube watts are louder", because similarly rated amps will not be similarly loud. In my experience, given a tube amp and SS amp rated the same, the tube amp will always be louder (if you push it into overdrive). I guess the bottom line is that, due to the characteristics of tube amps, they're "under-rated" in the sense that the rating is not their true maximum output. Whereas SS amps tend to be rated closer to their true maximum output. For example, I've read about 100W Marshall Super Leads (and/or Super Basses) that have had their maximum output measured as high as 175W.

SS vs tube power section preference is a matter of personal taste. I LIKE crunch in my tone, I set my rig up for that. I'm using Marshall VBA 400s, and they can go VERY loud, while remaining very clean. I use the gain control to add the dirt. Before the VBAs, I was using Super Basses, those are easy to push into distortion, and they are LOUD! :D

Where you would never gig a tube amp, I will ONLY gig tube amps (unless I'm stuck with a supplied SS back line, which sadly happens on occasion).

Cheers!
:bassist::bassist::bassist:
 
#14
Basically because tube power amps generally sound better when distorting than solid state power amps do, they are designed with that in mind. In a tube amp the preamplifier is generally capable of putting a hotter signal than the power amp can cleanly amplify. If the power amp is one hundred watts, it is one hundred watts. The power amp isn't louder because it is tube, it is just designed to be overdriven.

Solid state amplifiers generally are designed so when you turn the master volume all the way up, the power amp is getting exactly the maximum power it can before it starts to clip. The designers of the amp could easily have made the amp so it would clip the power amp just as much or more than the tube amp I was talking about earlier (and there are some who do), but it would sound terrible (to most people). The fact that it is solid state doesn't prevent it from distorting and sounding like it is louder like a tube power amp. The designers are just smart enough to know it wouldn't sound good to most people.

edit: I took to long to post this and it was already explained.

edit2: Hey, are you guys playing with David Schankle at Reggies soon? I saw the flier on your page, but I couldn't really read it and I figured I would ask to be sure.
 
#16
miner said:
Basically because tube power amps generally sound better when distorting than solid state power amps do, they are designed with that in mind. In a tube amp the preamplifier is generally capable of putting a hotter signal than the power amp can cleanly amplify. If the power amp is one hundred watts, it is one hundred watts. The power amp isn't louder because it is tube, it is just designed to be overdriven.

Solid state amplifiers generally are designed so when you turn the master volume all the way up, the power amp is getting exactly the maximum power it can before it starts to clip. The designers of the amp could easily have made the amp so it would clip the power amp just as much or more than the tube amp I was talking about earlier (and there are some who do), but it would sound terrible (to most people). The fact that it is solid state doesn't prevent it from distorting and sounding like it is louder like a tube power amp. The designers are just smart enough to know it wouldn't sound good to most people.

edit: I took to long to post this and it was already explained.

edit2: Hey, are you guys playing with David Schankle at Reggies soon? I saw the flier on your page, but I couldn't really read it and I figured I would ask to be sure.
Click to expand...

Are you asking me about Reggie's? If so, we played there with David Shankle, last year in November.

Cheers!
:bassist::bassist::bassist:
 

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