Wattage rating 120 amp/120 cab?

[cellardweller]

Sometime after I made my 5th lap around the block (making sure I wasn't be followed), but before counting my beerbottle cap collection, I realized that I HAVE to ask another question...

I can't find where it tells if the Univalve ships with tubes in it, and if so, what kind...

Okay, now I have to count and then feed my 50 cats...

 

[Outlaws]

Sometime after I made my 5th lap around the block (making sure I wasn't be followed), but before counting my beerbottle cap collection, I realized that I HAVE to ask another question...

I can't find where it tells if the Univalve ships with tubes in it, and if so, what kind...

Okay, now I have to count and then feed my 50 cats...

I bought mine used, plus mine is the BiValve, but I know the Uni ships with two 12ax7 preamp tubes and one powertube. The BiValve comes with two 6L6 powertubes stock, but I forget what the Uni ships with. Its either a 6L6 or an EL34.

 

[Outlaws]

??? The tech I go to had my 44 watt Super Reverb on the bench a while back, and full out it tested as 46 or 47 watts. It was a little hotter than the rating, but not much.

That would be the RMS output. But the peaks would be pushing ruffly 60-80 from what I understand.

Example, (since I know this one)

The actual wattage of a 100 watt Marshall SLP, when cranked, can reach upwards of 180 watts. Thats becuase the wattage (RMS) is rated before distortion is reached.

Infact, Marshall even says in the standard description of the 1960ax cab that is only rated for 100 watts, that you should not attempt to use a 100 watt head without an attenuator.

 

[boingoman]

Guitar amp speakers are made to handle distortion and get beat up. PA stuff is a completely different ball game.

The reason PA speakers can seem a bit more delicate is because of the difference in material that gets played through them. Guitar playing is very dynamic, and has a very low average level, with very short peaks.

Recorded music and any compressed signals have a much higher average level. PA speakers regularly have to put up with much higher average power levels than guitar speakers of the same wattage. The level of distortion handling or construction type doesn't really define guitar or PA speakers. Better speakers, guitar or PA, will have a higher average and continuous rating as compared to their peak than crappy ones.

 

[Farview]

The reason PA speakers can seem a bit more delicate is because of the difference in material that gets played through them. Guitar playing is very dynamic, and has a very low average level, with very short peaks.

Recorded music and any compressed signals have a much higher average level. PA speakers regularly have to put up with much higher average power levels than guitar speakers of the same wattage. The level of distortion handling or construction type doesn't really define guitar or PA speakers. Better speakers, guitar or PA, will have a higher average and continuous rating as compared to their peak than crappy ones.

Unless you are talking about an overdriven marshall on 11. That would have a pretty high average level. Guitar cabs are loaded with speakers that are supposed to distort. That is part of the sound.

 

[boingoman]

Guitar cabs are loaded with speakers that are supposed to distort. That is part of the sound.

Some people consider the speaker the most important part of an amp's sound. And indeed, they are a big part. I don't know if I agree that guitar speakers are supposed to distort, though. Certainly the JBLs in a 1970 Super Reverb aren't supposed to, and don't, nor do a Roland JC120's speakers. And a Marshall 1960A loaded with 75W Celestions will easily handle a couple hundred watts before it even breaks a sweat, much less starts to distort.
It seems to me that a speaker that distorted at moderate levels would be pretty useless. Any chance of getting a usable clean sound at gig volume would be lost.

And in any case, I can't see how being designed to distort could make a speaker more able to handle distortion.
If you've got some solid info, I'd love to read it.

 

[Farview]

I don't have anything for you to read, but 7 years of designing amps for KMD, Laney, and Randall along with being the guy that had to voice amps for Tony Iommi, Skid Row, Bon Jovi, Ace Frehley, Paul Stanley, Vinnie Vincent, Lonnie Mack, etc..., I have a little experience matching speakers to amps.
You are correct, a Roland Jazz Chorus does not have speakers that are made to distort, that would defeat the purpose of that amp, same with the Fender.

G12T-75s do distort, mostly in the low end. That, of course, also adds some of those wonderful upper harmonics that we love so much. You can get away with playing clean through them at loud volumes because you aren't pushing a lot of the really woofy lows that will push the speakers over the edge.

Speakers that are made to distort can handle it better because they are designed to handle it better. It isn't because they are made do distort that makes them handle it, it is because they have been made with it in mind.

 

[cellardweller]

This is the most interesting "thead drift" I've seen in a while

 

[ggunn]

That would be the RMS output. But the peaks would be pushing ruffly 60-80 from what I understand.

Absolutely true; that's the diff between peak and RMS power, but all ratings by reputable gear makers are RMS based and therefore take that into account. Tube amplifiers and solid state amplifiers both have the same apparent disparity between peak and RMS power, it's just a difference in measuring methodology.

BTW, the reason for the RMS (root mean square) method is that since the signal is AC and spends as much time below the line as above it, the true average power of any such waveform is zero. Squaring the instantaneous values, then averaging them over time, and then taking the square root , gives a nonzero positive (the positive root is always used) number.

 

[boingoman]

BTW, the reason for the RMS (root mean square) method is that since the signal is AC and spends as much time below the line as above it, the true average power of any such waveform is zero. Squaring the instantaneous values, then averaging them over time, and then taking the square root , gives a nonzero positive (the positive root is always used) number.

It is also the DC equivalent of the AC. That is, if you feed 100V peak-to-peak AC into a device, it will do as much work as if you had fed 70V DC into it.

So 120V RMS in your home will do as much work as 120V DC, and is somewhere around 170V peak-to-peak.

DC calculations are much easier to use than AC calculations, so having an equivalent DC measurement makes general calculating much easier.

It's the same reason we use nominal impedance of a speaker. Calling a speaker an 8ohm load is easier than figuring out an impedance curve, and allows us to use very simple DC resistance calculations when figuring out things like total impedance of a speaker load on an amp.