Power Amp Wattage Question

BBN

Fractal Fanatic
Can someone help me understand why it's ok to over power a guitar speaker if you're using a Solid State Amp?
I own much PA equipment and all of my speakers have Continuous/Program/Peak ratings which for example may be 500/1000/2000 watts. And I always power them right in the sweet spot (in this example...maybe 1500 watts).
Are guitar speakers (like a Vintage 30) be rated the same way. I have a few cabs i use for different situations (Mesa 1x12, Mesa 2x12 and a Mesa 4x12). All of these have Vintage 30's. And from what I can find on the web, Vintage 30's are rated at a 60 watt max. So this would lead me to believe that running 100-200 watts to one speaker will eventually fry it? Are the ratings on the Vintage 30 just conservative? I do obviously hear a volume difference between a solid state and a tube amp, but I am just trying to understand why "a watt isn't a watt" when it comes to over powering your speaker, and why powering your speaker over it's max rating isn't going to damage it? If someone could explain this to me, I would feel much better about plugging my (new) Axe Ulta into a Crown Powerbase 3 and into my Mesa 4x12.
Thanks in advance....
- Newbie
 
Yep, a V30 is a 60W speaker, so with one speaker you want to run a 60W or less amp into it and you can be pretty sure your speaker is safe no matter how hard you run the amp. If you have 2, you can run 120W. For your 4x12, you can run a 240W amp.
 
kruzty said:
Yep, a V30 is a 60W speaker, so with one speaker you want to run a 60W or less amp into it and you can be pretty sure your speaker is safe no matter how hard you run the amp. If you have 2, you can run 120W. For your 4x12, you can run a 240W amp.

Yes, that makes perfect sense to me, I'm just seeing other posts such as this:
viewtopic.php?f=13&t=15001
Where people are over powering their cabs with amps higher than the rating.

Again, just trying to understand why it's ok to do that...before I actually do it (and regret it).

Thanks.
 
BBN said:
I own much PA equipment and all of my speakers have Continuous/Program/Peak ratings which for example may be 500/1000/2000 watts. And I always power them right in the sweet spot (in this example...maybe 1500 watts).
There is no such thing as a "sweet spot" for speaker power.

Are guitar speakers (like a Vintage 30) be rated the same way.
There is no consistent methodology for coming up with a power rating for a guitar speaker. That number is even more meaningless in the case of guitar speakers than it is with PA speakers.

I do obviously hear a volume difference between a solid state and a tube amp,
I provided an explanation for this apparent difference. It's here: viewtopic.php?f=13&t=13614&p=128908&hilit=crest+factor#p128908

and why powering your speaker over it's max rating isn't going to damage it?
The power you apply to a speaker depends on how strong a signal you send to the power amp. You can use a 1000 watt amp to supply signal to a 3 watt speaker without ever damaging it. I use a Crown Macro-Reference power amplifier in my demo room rig, and it has powered speakers rated as low as 25 watts. I've never once damaged a speaker with that amp.
 
Jay - very interesting information. Thank you very much.
I'm off to plug my Axe into my Powerbase 3 and into my Mesa Cab.....rock-n-roll :twisted:
 
butterfly said:
Interesting info--this means I could power a 2x12 with Jensen P12 Ns (50 watts) with say an ART SLA 1?

Even in bridged mode... Just don't turn it up all the way.
 
I haven't blown enough speakers yet to be expert in this, however, I would recommend using speakers rating as a ballpark power-amp recommendation. Yes, you can use a vastly more powerful amp and be careful with the volume, but in the heat of the moment when your solo's getting washed out by a drummer who's decided that riding the crash cymbal sounds like a good idea, you know you're going to turn up a bit and hope it's all ok. :D

Again, I don't have experience is this, but the opposite can be just as bad (or worse according to some). I've read that a significantly underpowered solid state amp driven into clipping can potentially cause damage more easily than delivering too much power. The reason given is that the waveform delivers DC to the speaker, but I'm not convinced on that point. Certainly, continuous DC is bad for speakers, but in this case the amp is delivering in theory up to double the RMS (clean sinewave) power as a square wave, which at its extreme is an alternating DC waveform. Tube amps have a gentler overdrive transition and so are much less of a concern with this phenomenon.
 
GM Arts said:
I haven't blown enough speakers yet to be expert in this, however, I would recommend using speakers rating as a ballpark power-amp recommendation. Yes, you can use a vastly more powerful amp and be careful with the volume, but in the heat of the moment when your solo's getting washed out by a drummer who's decided that riding the crash cymbal sounds like a good idea, you know you're going to turn up a bit and hope it's all ok. :D

Again, I don't have experience is this, but the opposite can be just as bad (or worse according to some). I've read that a significantly underpowered solid state amp driven into clipping can potentially cause damage more easily than delivering too much power. The reason given is that the waveform delivers DC to the speaker, but I'm not convinced on that point. Certainly, continuous DC is bad for speakers, but in this case the amp is delivering in theory up to double the RMS (clean sinewave) power as a square wave, which at its extreme is an alternating DC waveform. Tube amps have a gentler overdrive transition and so are much less of a concern with this phenomenon.


The last part of your post is really why you should choose as much power as you can. You really don't want to risk overdriving a SS amp.

I say play by yourself one day, find the volume you think it will top out at (or find out how much power your amp is putting out scientifically ) then mark it on the volume dial of your power amp ( or a little lower since your playing is a dynamic thing).
~mx~
 
I've been running 750 solid state watts into a V30 4x12 for a year now at varying volume levels, and they seem perfectly fine. Just don't give your cab enough juice to damage the speakers. If it starts to sound like your speakers are breaking up too much, pull back. I was able to get it ball shatteringly loud without it sounding like I was about to damage anything, though. This was with the output level on the Axe-FX about half way up, and the level on the power amp a bit over half. I've never dimed it, and I think it would be a bad idea to.
 
GM Arts said:
I haven't blown enough speakers yet to be expert in this, however, I would recommend using speakers rating as a ballpark power-amp recommendation.
That is never an optimal solution. Even if a speaker's rating is a real one - meaning it was arrived at with one of the standard power-handling tests - it will have used pink noise with a 6dB crest factor as the test signal, whereas power amps are rated for sine wave power (3dB crest factor).

Yes, you can use a vastly more powerful amp and be careful with the volume, but in the heat of the moment when your solo's getting washed out by a drummer who's decided that riding the crash cymbal sounds like a good idea, you know you're going to turn up a bit and hope it's all ok. :D
Well, at least you'd be able to keep up with the drummer for a few seconds. :lol:

I've read that a significantly underpowered solid state amp driven into clipping can potentially cause damage more easily than delivering too much power.
This is a widely misunderstood phenomenon that affects multi-way speakers. It really isn't a factor with guitar speakers.

The reason given is that the waveform delivers DC to the speaker,
No. A square wave with no offset does not contain DC.

but in this case the amp is delivering in theory up to double the RMS (clean sinewave) power as a square wave,
This will happen if and only if the amp's power supply rail voltages are perfectly "stiff." Were you to drive an amp this far into clip, what comes out of it would not be recognizable. I.e., it would sound so bad that nobody with ears would be tempted to continue.

Tube amps have a gentler overdrive transition and so are much less of a concern with this phenomenon.
Tube amps will clip every bit as hard as ss ones.
 
Tube amps will clip every bit as hard as ss ones.

Judging from your attention to detail on most of your post, I am surprised that you would leave the discussion on this point.
Based on this statement, it seems that you are implying that tubes amplify in the same way that a transistor or semi conductor does - very linear (perhaps I am wrong in making that assumption?). According to the data sheets (and my actual measurements) tubes are not fully linear in thier operation. Depending upon circuit considerations, not the least of which is the PS section in tube power amps -especially guitar amps- significant distortion via compression occurs with a tube. This compression or non linear operation occurs before the tube reaches its maximum output. Without special design considerations, typical transistor (bipolar) will operate linearly (depending upon PS design). So while tubes can clip as hard as a ss device, the path they take to get there is different from most ss devices found in the average amp. There is a non linear aspect to tubes that does not exist with most (if any) ss devices. So, while I generally find your input very useful and informative, I must admit that I don't follow your reasoning here.
 
guitarmike said:
Based on this statement, it seems that you are implying that tubes amplify in the same way that a transistor or semi conductor does - very linear (perhaps I am wrong in making that assumption?).
Yes, you are wrong in that assumption.

This compression or non linear operation occurs before the tube reaches its maximum output.
I.e., tube behavior below clip differs signigicantly from that of transistors. The discussion was about endangering speakers by driving an amp to the point at which it is delivering a square wave, i.e., beyond the clip point. Both tube amps and ss amps can be driven into this region of operation.

I must admit that I don't follow your reasoning here.
It's a simple - and true - statement. Tube amps will clip every bit as hard as ss ones. I made no statement about behavior prior to the onset of clip.
 
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