What makes a tube amp 120 watts vs 100 watts?

[Swanation45]

Novice question I guess.

With so many tube amps being 100 watts what makes an amp 120 watts? (like a Peavey 5150 for example)
Is it something with the transformers that's different than a regular 100 watt head etc..???

Thanks!

 

[SpiderWars]

6L6GC tubes are 30W max dissipation and EL34s are 25W max dissipation so it's mostly based on that.

But the amp has to able to put out that power too, i.e. the power transfomer and output transformer and the plate voltage.

 

[Snave]

Part of it has to do with how conservatively a company rates its amps.

Mesa's 90 watts is closer to Marshall's 50 watts, for example. Peavey is probably overstating the 5150's wattage.

 

[JB 1970]

6L6GC tubes are 30W max dissipation and EL34s are 25W max dissipation so it's mostly based on that.

But the amp has to able to put out that power too, i.e. the power transfomer and output transformer and the plate voltage.

So, by that, I would think that you would have to bias the tubes at 100% to get those numbers, which would be a bad idea.

 

[Dave L]

6L6GC tubes are 30W max dissipation and EL34s are 25W max dissipation so it's mostly based on that.

But the amp has to able to put out that power too, i.e. the power transfomer and output transformer and the plate voltage.

So, by that, I would think that you would have to bias the tubes at 100% to get those numbers, which would be a bad idea.

It all depends on how you take the readings, the Marshall 1987 puts out well over 80w from two EL34s when cranked but is supposedly a 50w amp. A 100w 1959 can put out over 200w. These guitar amps use those tubes in ways the clean ratings never intended.

 

[Markedman]

watt
[wät]
NOUN
the SI unit of power, equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.

I had a ghetto-blaster that had "360 Watts *@ 10% distortion*" in big letters on the front that I could bury with my Fender Champ. Ever since that eye opening event, I realized that "watt" is a goofball that can be kicked around, where it's weighted and how much distortion allowed in the watt's rating changes everything.

"A 50 watt Marshall can bury a 90 watt Boogie"? A 1X12 Boogie Mark III combo can make a half stack Marshall seem like it's not even in the room, in my experience.

 

[Racerxrated]

watt
[wät]
NOUN
the SI unit of power, equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.

I had a ghetto-blaster that had "360 Watts *@ 10% distortion*" in big letters on the front that I could bury with my Fender Champ. Ever since that eye opening event, I realized that "watt" is a goofball that can be kicked around, where it's weighted and how much distortion allowed in the watt's rating changes everything.

"A 50 watt Marshall can bury a 90 watt Boogie"? A 1X12 Boogie Mark III combo can make a half stack Marshall seem like it's not even in the room, in my experience.

Seriously? Either you’ve never owned one, heard one or the 2204 you did hear had a problem. Love my Mesas BUT if I’m honest the Marshall will bury the 60w Mark. The 2204 will also be right there with the 100w HRG Mark. I’ve owned a ton of Marks but other than the Coliseum they will not have the push of a proper comparative wattage vintage Marshall.
Period.

 

[SpiderWars]

I interpreted the question as "Why are some tube amps RATED at 120W vs 100W" so hopefully that clarifies. You wouldn't bias it at 100% dissipation tho, those 100W rated Marshalls do put out well over 100W when biased at the typ 60%-70% max dissipation.

 

[Snave]

watt
[wät]
NOUN
the SI unit of power, equivalent to one joule per second, corresponding to the power in an electric circuit in which the potential difference is one volt and the current one ampere.

I had a ghetto-blaster that had "360 Watts *@ 10% distortion*" in big letters on the front that I could bury with my Fender Champ. Ever since that eye opening event, I realized that "watt" is a goofball that can be kicked around, where it's weighted and how much distortion allowed in the watt's rating changes everything.

"A 50 watt Marshall can bury a 90 watt Boogie"? A 1X12 Boogie Mark III combo can make a half stack Marshall seem like it's not even in the room, in my experience.

Seriously? Either you’ve never owned one, heard one or the 2204 you did hear had a problem. Love my Mesas BUT if I’m honest the Marshall will bury the 60w Mark. The 2204 will also be right there with the 100w HRG Mark. I’ve owned a ton of Marks but other than the Coliseum they will not have the push of a proper comparative wattage vintage Marshall.
Period.

This is correct. I never said one would bury the other, but a 90 watt Mesa would have trouble keeping up with actual ~100 watt amps (Marshall, VHT, etc). Hence the need to make 150W models with six power tubes.

 

[WarHed]

Plate voltage, bias and tube max plate dissipation

 

[itsme]

Plate voltage, bias and tube max plate dissipation

This...

Bogner XTC is 120 watts with 4 EL34's. It's how you run them with plate voltage etc...

 

[skullfxr]

I think in the modern world, it's just how they choose how to market it. I understand the technical side, but I have not seen the number hold true in the real world. Peavey thinks 120 watts sounds better. The actual results vary quite a bit.

 

[stephen sawall]

Novice question I guess.

With so many tube amps being 100 watts what makes an amp 120 watts? (like a Peavey 5150 for example)
Is it something with the transformers that's different than a regular 100 watt head etc..???

Thanks!

Headroom and using different measuring methods. There is no standardized method that is used to measure.
The rating is clean power. The maximum output is often double or more.
Watts is not dB's....these are completely different measurements.

 

[Markedman]

Oh, I understand you guys now. I was mistaken for thinking that, with all thing equalish, of course a 4X EL34 amp would be louder than a 4X 6L6 running at extremely high plate voltage (Boogie Mk.IIC+) and a EVM12L that can't equal the high power like a 30 watt celestion can.

My bad. Thank you for the insight, it is greatly appreciated. Boy, I look stupid! All that math and numbers add up sometimes. But I am also lucky, my rig can run at 15 - 500 watts in an instant, so no Marshall or Fender type rig would challenge my rig for loudness anyway, ever.

“ My Marshall goes to 11 and your boogie only goes to 10, 11 is one more than 10, I am one louder!“

 

[stephen sawall]

I owned plenty of Marshall and Mesa amps. The Mesa stuff is in almost all cases capable of being louder. What's the difference anyway....all if them go louder than anyone needs.

 

[skullfxr]

i said it once and realize the technical aspect. due to the unstandardized way of measuring wattage, a lot of it is marketing. peavey wants to sound like a badass saying 120 watts over 100 watts. in reality i have no idea what it is on that amp, but the lack or standard protocol, its just a way of marketing an amp. saying that, standard protocol theoretically exists, but i really don't think its actually practiced.

 

[nightlight]

An interesting one is the Savage 120. Only two KT88s in there. On the other hand, the VHT Sig:X, which also has two KT88s, is only 100 watts.

I haven't dared diming either of them to figure out which is louder.

 

[skullfxr]

An interesting one is the Savage 120. Only two KT88s in there. On the other hand, the VHT Sig:X, which also has two KT88s, is only 100 watts.

I haven't dared diming either of them to figure out which is louder.

I always thought that about my sig:x

 

[Wizard of Ozz]

RMS power available and output transformer.

 

[scottosan]

Plate voltage comes into play as well. At 400v on EL34s. Your looking closer to 80 watts. At 525v you probably closer to 110-120 watts.