How Much Power Do I Need?

[Bytrix]

For a guitarist just starting out with a small band what kinda amp power am I going to need? I know there are a bunch of things to take into consideration like how many people we'll be playing to, the size of the places and what other equipment I have and I've never used anything other than small combo-amps which has been fine up to now.

I run a V-Amp Pro along with a few other rack units and some pedals straight into a 30w combo amp at the moment (on it's clean channel) and I want to go down the cab path, so first of all what wattage should I look at in a cab, and if I get something like a 400w (like the stereo behringer cab I am thinking of getting), will it still sound good at 200w?

So If I'm getting a cab, I then want a head/power amp to drive the signal from my V-Amp into the cab.. BUT I don't want it to saturate the sound or change the tone from the V-amp to the cab, I just simply want it to amplify and be capable of running the cab at it's max (if that's ever needed)), any recommendations?

I'm on a fairly tight budget, and I've just got so confused looking at cabs/heads/poweramps that I have no idea what I actually need in terms of power.

Any help is appreciated...

[fookgub]

How loud your rig gets is heavily dependent on speaker efficiency. Most 4x12" cabs are going to be a lot more efficient than your combo amp. Run 30W into your average cab, and it'll drive you out of the room with your hands over your ears. IMHO, 200W is too much. Buy amps based on how they sound, not how much power they supposedly have. Nearly any head out there will drive a 4x12" to excruciating levels.

FYI, I have a 75W head and an 8-ohm cab that's probably around 106 dB @ 1W/1m. I've never bothered to check, but I'd say I use maybe 10W at band practice levels.

One other thing to consider, the power rating for cabs are nearly useless. First, they're not indicative of how much power your can run into the cab before damaging it. Those power ratings are for heat, and you will destroy your speakers from over-excursion long before you melt the voice coils. Second, they're not accurate. Manufacturers will often use 'peak' power instead of RMS, and they'll usually inflate the number, too. Unless you're buying the drivers themselves from a reputable manufacturer, and they come with datasheet, I wouldn't trust the power ratings at all. About the only thing a power rating *might* be able to tell you is that, all other things being equal (and they almost never are), a cab rated for more power is probably less efficient.

Anyway, the best thing to do is just use your ears. Try out different head/cab combos and see which get loud enough for you.

And yes, a 400W cab will sound fine with a 200W head (and keep in mind that you won't actually be putting anything *close* to 200W into it).

Edited February 28, 2006 by fookgub

[Bytrix]

hmm, well this is the cab I was looking at getting, I like to use stereo effects and this seemed like a good option:

http://www.behringer.com/BG412S/

'Power rating: 400 Watts into 8 Ohms mono, 2 x 200 Watts into 8 to 12 Ohms stereo.'

I know I'll be going nowhere near 200W or 400W and if I ever do it's years away, but I don't want to buy something that I have to replace/upgrade in 6 months time.

It's all this stuff I don't really get (I know I'm a complete 'noob'). Anyone just want to recommend me some heads to run my V-amp into one of these ?

[JohnH]

Ive have recently bought a secondhand Marshall 4x12, and am looking at heads. One thing that i have done in the interim is add an extension socket to my combo (a small 10W practice amp). This works really well and is surprisingly loud and clear. So Im suggesting that this might work even better with your 30w combo, and it would give you a chance to get to know your cab and how much power it really uses.

Two things to watch for:

Match the impedances of speaker and amp. If the combo works on an 8ohm speaker, you would only be using one channel on that Behringer cab, I believe it is 2 x 8 ohms in stereo.

The other thing is to wire the extension socket so that there are no momentary shorts or double connections as youi insert the plug. I used a switched socket. It cuts out the internal speakr before connecting the cab.

Doing this is cheap and simple, but get help if you are not confident with such wiring. also, if your combo is new, it could affect warranty.

John

Edited February 28, 2006 by JohnH

[ROBERTLATHAM1]

30watts is plenty for most small bars. 100watts will put you in any venue you want to play most peeps really only need a 50watt tube head most of them hit thier sweet spots at a tolerable level. i use several heads one as a pre amp mainly for tone and two others for power one is about (harmony) 45 watts the other is a (bogen) 100watt monster. yhe pre amp head is a marshall vs100. i use a 4x12 with g12m70's and the 100db mark aint sh--!

[Hoser Rob]

A couple of really good guitarists I know who have both played a ton of gigs in the last 25 or more years swear that the Deluxe size (20 watts) is the ideal size for a tube amp.

They're small enough to turn up all the way at small gigs without overpowering everyone else, and in larger gigs you just mic them into the PA. And they're loud enough to be heard onstage then.

100 watt (or more) amps were invented before they had decent PAs like they do today. You don't need that much power now. Kiss used to actually route the guitar signal to small Fender amps and mike them. The wall of Marshalls were just for show.

Micing a small amp as opposed to blasting a 100-200W one right behind you is a lot better for your hearing too.

[Jeff B]

Micing a small amp as opposed to blasting a 100-200W one right behind you is a lot better for your hearing too.

What did you say ? I could not hear you..........

I used a boss multi effect, a stack in a rack distorion thing, and ran it to a 125W PA amp that I got for $100

That to a peavey 4x12 rewired for 4 ohms. At 75 percent, it was loud enough that no one else in the house could hear anything but me playing.

If you want stereo, get a decent power 2 channel and go with it. If your processor is designed to be run direct to PA, it does not even have to be a guitar amp, though you might like that sound more. Run that to a stereo guitar cab and go.

We have a decent sized youth praise center (small club sized ) and my Peavey 30 watt practice amp is way loud enough to fill the place. It has a single 10"

If you like the behringer you could go with a combo http://www.behringer.com/GMX212/index.cfm?lang=ENG

Edited March 1, 2006 by Jeff B

[fookgub]

'Power rating: 400 Watts into 8 Ohms mono, 2 x 200 Watts into 8 to 12 Ohms stereo.'

This does not make sense. I don't understand why manufacturers do this type of thing... it's like they deliberately want to confuse people.

Anyway, I don't have much love for Behringer. This could be a fine cab (I don't know... I've never heard it), but it looks cheaply made, and Behringer doesn't have much of a reputation either. For a bit more cash you could get into a lot of better stuff. Give a thought to Carvin and Avatar. Also, look for used stuff. I saw a Marshall 1960 stereo cab go for $300 a little while ago.

[Bytrix]

So basically a 4x12 isn't the way to go? and I should maybe instead look at a 2x12 combo?.. something like that behringer (but I really want something simple, there's no point having a load of controls on the amp itself because my V-amp can output hundreds of different amp and cab tones....

[Jeff B]

Well, I wasnt particularly suggesting the Behringer. In fact I have never heard it, just using it as a starting point.

Since this is project guitar, I am going to suggest building something.

A 10" eminence or celestion can be had for under $40

A 12" for under $50.

So get 2 of one or the other, build a basic cab with a baffle to seperate the 2. You can have a dual 10" for less than $125, dual 12" for less than $150.

Get an amp similar to this

http://www.music123.com/Samson-Servo-200-P...p-i229215.music

and you have a true stereo setup that will absolutley scream for under $300.

Its rack mountable (you said you already have a rack) and will color your sound little to none.

[marksound]

If you're running a modeling preamp, you'll want something as transparent as possible. The Atomic Reactor 112 is designed specifically for what you're doing. Mic it up and you're good to go. You won't break your back moving it, either.

[Bytrix]

Thanks Jeff B, those power amps look nice (I've been looking around for power amps but they're all way too powerful for what I need. I was wondering about building a 2x12 cab too.. perhaps I'll take that path.

Does anyone know where to buy Celestions in the UK?

[edit] actually just found a site with a massive range of Eminence speakers (bluearan.co.uk).

[Bytrix]

ok, more noob questions:

Does anyone have any references for someone who's never built a cab?, what woods to use, how thick, general guidelines on dimensions etc..

I've read a little into it and I think I might have a go at 2* 2x12 cabs:

one fitted with 2* Eminence Patriot Series - Blue Tick Hound 75W 12 inch 8 ohm ;

the other fitted with 2* Eminence Patriot Series - Screamin Eagle 75W 12 inch 8 ohm

Both wired in parallel as I've read it's 'safer' than series, meaning each cab would be capable of 150W @ 4 ohms ?

So a power amp like the Alesis RA300 Reference Power Amplifier one would be suitable : ?

Thanks for putting up with my stupid questions again I'm quite looking forward to having a go at building a cab now, maybe once I've built one (or both) I might finally get the courage to start making the neck for my guitar.

[Jeff B]

One cool thing about that, you could always just use one cab if you needed. Actually, I would build one first and then have a go at the second, If you find the first is not loud enough. Just make it with 2 inputs. This looked to be a decent article on cab building, altthough I did not read it all the way through.

http://colomar.com/Shavano/stereocab.html

Just search google, I found tons of sites.

[Bytrix]

Thanks, I had searched and found a few 'this is my cab' sites, but nothing with a real tutorial or specifications of the wood used (like how thick it should be, how much support the thing needs so it won't come apart etc..).

I was planning on just building one first, better to get it built then try a second once I know what I'm doing.

[jnewman]

If you just build a rectangular carcase out of 3/4" void-free plywood with box-jointed corners, you have what pretty much everyone in the history of guitar cabs has used for guitar cabs . If you do the box joints right, you don't need any internal supports - when I finished mine, I could stand on it or sit on it and it wouldn't even wobble.

[Bytrix]

Well I officially have 'the bug' now, spent all morning here at work looking for the parts. Found some 18mm plywood from a local timber merchants, the speakers from that bluearan site, and all the other bits to complete the cab from maplin. I can't wait to start this now.

Maybe I should document it and submit it as a tutorial for the main site? Even though I won't be looking much into the science of building a cab I think it'd be good to have some kind of guide on there.

[ansil]

ITs more about tone than wattage anyday. I had to beef up a few parts but i used two similar rigs for years and they handled road abuse to boot. for smaller stuff usually studio and live work i used a 4*12 with jensens and a fender squier 15 amp cranked wide open [actually volume was on8.5] but it powered the 4*12. before that or if i needed more volume i would use one of the old SS champs that had a blown power chip into an old fender bassamp from the early 90's.

You may think it would sound impossible from just reading that but its true what they say a little amp cranked wide open sounds so much better than any other amp.

any my .02

[JohnH]

If you are getting into cab building - here are the plans for the mighty Marshall 1960 4x12 slant cab

http://www.18watt.com/Storage/1960A-Slant-Cab_rev1.pdf

The cosmetics of a cab look like the hardest part - but that is your choice as to what you want. The technical part of building a cab that works as well as any other is just basic carpentry.

John