#1
I'm trying to better understand the relationship between a tube amp's output and the connected speaker's wattage handiling.

I realize that a fully maxed tube amp will put out well above its rated wattage... but my question is, how much more?

I have a 50 watt head and I'm looking for a 2x12 to play through. I have always been a fan of Greenbacks and G12H30's (25 and 30 watts) but I'm worried that a combined cabinet handling of 50 or 60 watts won't be enough for the 50 watt tube amp. But, I'm curious because I've seen some recent manufacturers using a 25w Greenback for a 25w amp (Dr Z, for example).

I realize an approximate 100w cabinet would be ideal (4x12 Greenbacks, for example) but space issues have me leaning toward a 2x12. I could just throw V30's in there (60 watts a piece), but I really love the sound of lower wattage Celestions.

Any thoughts / suggestions?
#2
There are two things to consider in this equation:

1 - Speakers are usually rated quite conservatively so they can probably handle more power than they say.

2 - Do you really expect to ever fully crank a 50w head?

Beyond that I don't think I can help; I don't know much more at all.
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#3
Thanks for the response! I got in touch with Dave at Avatar Speakers (the company that I'm ordering my cab from) and he said that a 60w cabinet should be able to handle a 50w amp.

But, now I'm worried about massive amounts of speaker clipping at high volumes.

I play in a band where I'm the only guitarist...just guitar and drums, and I rely on a pretty thick wall of guitar... when we play out, I usually have the amp cranked to about 8/10. I'm sure a 60w 2x12 would be fine, but I'd like to understand the details before I take the plunge.
#4
You should be fine. Remember, Greenbacks were only rated at what, 15 watts, in the 60's and they held up behind 100 watt heads.
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#5
Quote by CutlassSupreme
You should be fine. Remember, Greenbacks were only rated at what, 15 watts, in the 60's and they held up behind 100 watt heads.

i was going to say the same thing.
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#6
That's very true.

I guess I'll give it a shot. I wish I had the money / space for a 4x12 and load it with Greenbacks, but them's the breaks I suppose.
#7
Quote by CutlassSupreme
You should be fine. Remember, Greenbacks were only rated at what, 15 watts, in the 60's and they held up behind 100 watt heads.


Not quite, they are rated at 25w, and in the 60's most musicians using a 100w head would use 2 100w cabs (each loaded with x4 25w Greenbacks) to be on the safe side. A 100w Plexi will be kicking out 100 watts clean, but when you turn it up and hits the overdiven zone it's kicking out at least 150 watts. So using a 100w head with a 100w cab ain't the best idea, the rule of thumb for me is making sure your cab has twice the wattage of your amp to be safe.


Fair enough, 12 inch speakers can handle pushing out a lot of air, put if it is too much then they won't be able to handle it properly.

Ok, a lot of people use amps with clean wattages that equal their cab's handling capability and they say it works ok for them, but IMO you should play it safe, as good speakers cost a helluva lot to replace when you are a poor student
#8
I am indeed a poor student.

To be on the safe side, I think I'll go with dual V30's (60w each). I'm not a big fan of their huge bass response, but what the heck, I can always part it out on Ebay if it doesn't work out.

Or, maybe I should save a bit and spring for a 4x12 Greenback cab.

Decisions, decisions.
#9
Well, that's what I did (only it wasn't a Greenback cab, it was a G12H-30 loaded cab) and a word of warning: it is huge, and incredibly heavy. But if you have a helpful mate, and space in the back of the car (with back seats folded down) then it is most definately worth it, the sound is beautiful
#10
the whole size and weight thing is a big issue... I know I would absolutely love the 4x12 with Greenbacks or G12H's, but I am not playing out enough right now to warrant a huge cab...also my practice space is in a basement down a flight of stairs. The Avatar website estimates a weight of 100 lbs for the 4x12. I can just see it falling down all those stairs... I think my back will appreciate a 2x12!
#11
Yeah, well go with the 2x12, or perhaps if you wanted to spend the money you could get 2 2x12 cabs, each loaded with your beloved Greenbacks? It would cost more, but you would get the speakers, get the ease of transport and also have enough wattage for your speakers
#12
Quote by ECwomantoneman
Yeah, well go with the 2x12, or perhaps if you wanted to spend the money you could get 2 2x12 cabs, each loaded with your beloved Greenbacks? It would cost more, but you would get the speakers, get the ease of transport and also have enough wattage for your speakers


x1. It's better to have too much then not enough. And you'll have peace of mind about it all. What about mic'ing your amp?
#13
Quote by ECwomantoneman
A 100w Plexi will be kicking out 100 watts clean, but when you turn it up and hits the overdiven zone it's kicking out at least 150 watts.

Why is my bull**** allert light flashing when i read this?
So you say that if your amp reaches and crosses the point of saturation, it has more wattage than 100W?

How come that my 4*12 greenbacks (100W) can hold my 6505 (120W) easily when i put it on 6? Thats over the saturation point, you know...
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Last edited by LP_CL at Jun 13, 2008,
#14
Quote by LP_CL
Why is my bull**** allert light flashing when i read this?
So you say that if your amp reaches and crosses the point of saturation, it has more wattage than 100W?


Obviously you have a dodgy light


Post 3, read it

https://www.ultimate-guitar.com/forum/showthread.php?t=473149


and my dad, who has nearly 35 years of electrical engineering experience, will testify that this is true. 100w clean will not mean 100w cranked, it will be a lot more.

12" speakers will cope with a lot of air getting pushed through them, more so than smaller ones, meaning a slight compensation for the wattage differential. But if you keep stressing them over and over they will most likely pop eventually.

Plus, whilst 6 is past saturation point, it's not going to be kicking out nearly as much wattage as turning it to 8 and up.
#15
^k fair enough. I guess that Greenbacks must be tuff @ss speakers.
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#17
Quote by LP_CL
Why is my bull**** allert light flashing when i read this?
So you say that if your amp reaches and crosses the point of saturation, it has more wattage than 100W?

How come that my 4*12 greenbacks (100W) can hold my 6505 (120W) easily when i put it on 6? Thats over the saturation point, you know...


They can Handle it.. Its just how long they can take it.

I ran my ENGL (60 watts) through a 2x12 with GB's (50) for a while.. Never had any problems I guess your are just pushing them to the point where its not safe territory and could potentially blow the speakers.
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#18
BTW, something people have neglected to mention is that while matching a 50W head to a more powerful cab (let's say rated 100W)...For some people, getting the cab as close to the head's wattage as possible is desired.

If you want speaker distortion, which is an element of classic rock, you should have your cab's rating matched as close to your head as possible.

Speaker wattages are rated conservatively, meaning that yes while your head may exceed it's wattage when it's full saturated, your speakers are built to handle more than they are rated at.
#19
Quote by forsaknazrael
Speaker wattages are rated conservatively, meaning that yes while your head may exceed it's wattage when it's full saturated, your speakers are built to handle more than they are rated at.


Exactly.

You think guitar speaker manufacturers aren't aware of how guitar amplifiers are rated? You think some jabroni on the internet has a better idea than these guys? The fact is that guitar speakers are designed to carry the wattages they're listed at as they relate to guitar amps and more. The AC30, which is technically rated at 33W, comes equipped in it's highest end configuration with a pair of 15W Alnico Blues. Do you think they sell that amp with a plan to blow those speakers? No, they're designed to deliver the sound of that amp fully cranked, along with the lineup of overdrives and boosts you may want to run in front of it.
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#20
ok, I have made up my mind, thanks in part to all the useful advice above.

I am ordering a 2x12 with G12H's giving me a rated 60 watts. According to some online research, most modern speaker companies design their speakers with a MAX handling of almost twice their rating. I enjoy some cone breakup, and do not intend on FULLY cranking my amp, so I am confident my speakers will be A-OK.


^By the way, I am of the school of thought that bigger is not always better. If I had the convenience of a good venue with a good sound system, I would be playing my heart out to the knee-buckling sounds of my 60's Reverberocket at its sweet spot all miked up. But the sh*tty gigs in North Jersey have left me no choice but to knock some heads off with some big air movement. Also, being the only instrument besides the drums, I really need to fill the room.


Thanks for all the help
#21
Glad you didn't fall for misinformation there and I agree 100 % with slats.
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#22
okay so sorry to steal you're speaker thunder there ts but i also have a question along the same lines
i'm planning on possibly getting a marshall jcm 900 100 watt 4100 head
but i'm going to run it through my 120 watt rated mg cab
only for a couple months, then i'll get a 1960
so i'm wondering if i can run the full 100 watts through it?
i know i can run 50 watts
but i was wondering for 100?
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#23
Should be fine. Good riddance if you destroy it anyhow.
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