The basics of pairing heads and cabs

CannyBusDriver · #1 12-04-2011, 06:28 PM

I went to guitar center today with the Acoustic 370 i recently bought off guitar center online. I asked the guy what cab to pair it up with and I was going to pair it up with a 800w cab, because i thought you were supposed to pair a head with a bigger cab. Apparently its visa versa, I need to pair my 300-ish watt head with some cab LOWER than 300 watts. Too what extent can this be taken? Can i pair my 370 Acoustic head with a 100w cab? a 50w? or is it optimal to get as close as possible to the head wattage without going over...???

Im a huge noob with amps. On a sidenote, when i paired this Acoustic 370 with an acoustic 200 watt cab it sounded INCREDIBLE. There are a million tones on this head, and there was no static, humming or anything. It was clean sounding when i wanted it, and growly when i pushed it. Its honestly the best amp i have ever played through but this is because my experience with amps have been 15w crates and my 400w pos Behringers. ehh the worst part is i have to put it back in its christmas box and wait till christmas...

Joe Louvar · #2 12-04-2011, 07:01 PM

Quote:

Originally Posted by CannyBusDriver

ehh the worst part is i have to put it back in its christmas box and wait till christmas...

Why not leave it out of the box a put a ribbon bow on top of it - that way you can still use it and it will be prettier than in a box.

**Hapa** · #3 12-04-2011, 07:13 PM

Your wordage seems funny...the 370 is an amp correct? you say you are going to pair it with an 800watt amp?

REVISED AFTER COMBING OUT MY OWN IGNORANCE:

With that head the amp may likely distort when you play it loud, the cab will be able to take it but it won't sound that good being a ss amp. This might be a point of argument running along the lines of an Ampeg SVT into an 8x10, tube watts act differently to our ears but the SVT is by no means a clean sound. Many people try to achieve this setup on purpose because it is a type of sound, not mine btw. Many people have done this, you will be loud with an 8x10 running 300 watts but not clean, 880watts rms into an ampeg 8x10 (handles 800 rms 1600 peak) is glorious overkill, and marginally louder but it is clean volume and a lot of spl.

This kind of sound is old. The engineering angle of efficiency is showing its age with this one. More speakers moving air is a good way to achieve desired SPL and volume. This was conceived when wattage was harder to achieve and was really, really, heavy. (ever seen a 1200 watt amp from the 60's?) Now we have 5 lb 1000 watt amps that sound great with cabs using speakers that are built way better than they ever have before.

Properly powering a speaker has a lot of perks as the speaker has enough energy on tap to move the way your amp/fingers are telling it to. One does not always need the extra spl from more speakers to create more volume if the frequencies that you want to hear are being properly reproduced from a speaker with proper power. For example the Bergantino ip112ER puts 500watts into a single 12, it is devastating. It is capable of creating a lot of clean volume that many find to be the the best.
But overpowering speakers too much leads to heat dissipation issues an one can fry the voice coil.

Looking at specs look at its nominal (normal) power output the peak is frequently used to advertise the output of the amp but is kinda misleading. The peaks are the momentary output of the initial attack of a note, ie the first few Milliseconds of a slap, or the first release of a finger pluck before it goes into oscillation.

If you are new then remember to where earplugs, if not getting a set of custom molded plugs. 880 watts into an 8x10 spells hearing damage, if you can't be heard with that behind you get a new band. Guys that use high power (myself included) are trying to achieve the cleanest sound possible with as much headroom as possible. Or being loud enough and having the ability to dig in to the bass and not have our sound fall apart.

MuzikMan · #4 12-04-2011, 07:19 PM

Underpowering? Really? This myth has legs...................

brendanbassist · #5 12-04-2011, 07:21 PM

So much fail happening in this thread. You CAN NOT UNDERPOWER a speaker. There are numerous threads about this in the "stickies" section. That being said, just because an amp is rated for 300 watts doesn't mean it can take a full 300 watts from the head. Again, check the stickies.

BurningSkies · #6 12-04-2011, 07:24 PM

Square wave clipping doesn't blow woofers. It can give trouble to tweeters.

billfitzmaurice · #7 12-04-2011, 07:56 PM

Quote:

Originally Posted by CannyBusDriver

i thought you were supposed to pair a head with a bigger cab. Apparently its visa versa

It's neither. A 2:1 amp to speaker power rating is OK. So is a 2:1 speaker to amp power rating. The advantage to having a higher powered amp is you can add another speaker at a later date and have plenty of power available to push it. But that's the only advantage.

**Hapa** · #8 12-04-2011, 08:09 PM

Quote:

Originally Posted by brendanbassist

So much fail happening in this thread. You CAN NOT UNDERPOWER a speaker. There are numerous threads about this in the "stickies" section. That being said, just because an amp is rated for 300 watts doesn't mean it can take a full 300 watts from the head. Again, check the stickies.

I don't want this to become another underpower thread but obviously you have not seen or had a meltdown happen. Also you don't seem to regard the thousands of amp/speaker repair shops that are in business because of this.

Uhh, if a Cab is rated at 300 then by definition means it should take 300 watts from the head. If not its not rated properly.

If a cab has less power than it needs to operate it creates distortion at volume, then the cab with proper power will create less distortion at volume. The more distortion the more heat, the more heat, equals damage.
If you can't hear that you need to get you ears tested, maybe your nose too. Anyone that has been playing long enough has smelled burning speaker/ electronics.

**Hapa** · #9 12-04-2011, 08:13 PM

What I originally posted here was ignorant BS.

Nev375 · #10 12-04-2011, 08:16 PM

This thread is underpowered and it's clipping my brain coil.

slaps76 · #11 12-04-2011, 08:25 PM

So if you have an amp that's rating equally matches the cab's rating, does that mean you have to keep the amp cranked to avoid "underpowering" it? I don't understand the whole underpowering thing.

Either way, you can get an amp that's rated higher than the cab, you just have to be wary of not driving it too hard.

Nev375 · #12 12-04-2011, 08:28 PM

Underpowering is a word invented by salesman and manufacturers to sucker people into buying more stuff that they don't need.

BurningSkies · #13 12-04-2011, 08:31 PM

Quote:

Originally Posted by Hapa

Square wave clipping is not the same thing as a square wave synth/fuzz pedal sound. One is a soundwave, one is powered signal reproduction loss.

I know what it is. I don't see that anyone has suggested we're talking about a synth or a 'fuzz pedal'.

It still doesn't kill woofers.

Pilgrim · #14 12-04-2011, 08:37 PM

Quote:

Originally Posted by slaps76

So if you have an amp that's rating equally matches the cab's rating, does that mean you have to keep the amp cranked to avoid "underpowering" it? I don't understand the whole underpowering thing.

This question points out the fallacy of the "underpowering" argument.

Amps are almost never run at full power; therefore, all cabs are essentially "underpowered" almost all the time.

If you DO run a low-powered amp wide open so that you introduce clipping and other undesirable transients, you can very well damage a speaker...but that is not a function of the amount of power that the amp has, it's a function of abusing the amp so that it puts out a signal which speakers find difficult to tolerate.

**B-string** · #15 12-04-2011, 09:05 PM

^+1
The "under-powering", need twice the amp as speakers (in a bass rig? REALLY?

) and any other like speaker cab ratings being completely honest....

:he lp:

I need a BEER

brendanbassist · #16 12-04-2011, 09:17 PM

Quote:

Originally Posted by Hapa

obviously you have not seen or had a meltdown happen.

Meltdown? Of the head or cab? If you "meltdown" a speaker, its from OVERPOWERING; if you "meltdown" a head its from driving the head to hard, which has nothing tho do with the power rating of the cabinet.

Quote:

Originally Posted by Hapa

Uhh, if a Cab is rated at 300 then by definition means it should take 300 watts from the head.

Correct.

Quote:

Originally Posted by Hapa

If not its not rated properly.

Also correct. "Ratings" given are for thermal limits of the speaker; for woofers that is almost never a power level that can be reached without blowing the speaker due to overexcursion.

Quote:

Originally Posted by Hapa

If a cab has less power than it needs to operate it creates distortion at volume, then the cab with proper power will create less distortion at volume. The more distortion the more heat, the more heat, equals damage.
If you can't hear that you need to get you ears tested,

No. that's nonsense. Cabs don't have a "minimum" voltage level. If I turn down the volume on my amp, I don't hear distortion. Sometimes turning UP can cause distorion from the speakers, but again, thats OVERPOWERING.

Quote:

Originally Posted by Hapa

maybe your nose too. Anyone that has been playing long enough has smelled burning speaker/ electronics.

Yep, smelled burnt electronics plenty; as an electrical engineer. Smelled plenty of burnt amps. Never smelled a burnt speaker caused by underpowering it though. Except that one time, when I turned all my amps off, and then all my cabs spontaneously combusted from not receiving any power. The underpowering was so tremendous that I couldn't get the smell out of my house for weeks. Yes, that was sarcasm.

CannyBusDriver · #17 12-04-2011, 11:13 PM

jesus christ. First off, I am sorry for starting this debate up...

Second off, i just read this whole thread and its still confusing...

and third off

I NEED ANOTHER BEER......

What I am getting is that, underpowering is not a problem... but overpowering a small cab with a big head IS???? or am i just that confused.........(is it wrong to say I NEED ANOTHER BEER twice in the same post??)

**B-string** · #18 12-04-2011, 11:20 PM

Quote:

Originally Posted by CannyBusDriver

jesus christ. First off, I am sorry for starting this debate up...

Second off, i just read this whole thread and its still confusing...

and third off

I NEED ANOTHER BEER......

What I am getting is that, underpowering is not a problem... but overpowering a small cab with a big head IS???? or am i just that confused.........(is it wrong to say I NEED ANOTHER BEER twice in the same post??)

Must be good beer, you got it right!

The caviot is a high wattage amp head can be used with a small cab, just don't expect to turn up very high without blowing the cab.

brendanbassist · #19 12-04-2011, 11:22 PM

Quote:

Originally Posted by B-string

Must be good beer, you got it right!

The caviot is a high wattage amp head can be used with a small cab, just don't expect to turn up very high without blowing the cab.

Yup! So now the real question is.... what kinda beer are you drinking CannyBusDriver? Sounds like a good one.

CannyBusDriver · #20 12-04-2011, 11:24 PM

ehhh, its the WORST beer, Natty Ice... but thanks for the help people. My bad for not checking stickies, i used the search tool and didnt find anything. I think i'll just try and shoot for a 300-400w cab, maybe try and find the original matching 301 cabs that acoustic used to pair with these.

Wish I had Sierra Nevada or something, cant always afford the micro brews...(college)