Im confused: wattage for 210 and 410 cabs.

[Meddle]

Hello all

I've been trying to find the solution to a problem. Maybe my problem is stupid, as people don't seem to ever ask the exact question.

In my head, having two 8 ohm 210 cabs makes more sense than having a single 4 ohm 410 cab. You can split the rig for smaller gigs, or build it up for louder ones.

However I've been looking at 210 cabs, and they are always rated as having a lower wattage than their 410 brothers. This might be common sense. I've looked at TC electronic and Peavey 210s and found this to be the case.

In my mind, if you sawed a 410 cab in half (hypothetically), and kept one half, you would lose half of the wattage handling capability? Therefore two 210 cabs rated at 175 watts rms would in fact 'create' a 410 rated at 350 watts rms when both hooked up to an amp?

I'm looking at getting a ~300 watt @ 4 ohm head, so creating a 4 ohm load with two 8 ohm 210 cabs seems an 'elegant' solution.


Am I barking up the wrong tree? I know Celestion green backs are rated at 25 watts, yet guitarists can run 100 watt heads through 412 cabs with four green backs inside them without farting out or burning up the speaker cones.


I should have paid more attention in high school physics lessons...

[vin*tone]

Yeah - except the 210's can often handle more than half a 410.

And remember - you don't need to 'match' you rated power handling exactly. If you have a 300 watt head and want to run 2 TC 210's (each rated 400) The TC cabs will handle them just fine. There is no such thing as underpowering a cab. It's only if you exceed the speaker rating where you could run into issues.

[arai]

Originally Posted by Meddle

Therefore two 210 cabs rated at 175 watts rms would in fact 'create' a 410 rated at 350 watts rms when both hooked up to an amp?

Yes

[Downunderwonder]

You figured it all out all by your good self, Sir. Sure you're not from the West Isle?

When you get the 2x10 pair, stack them tall and you will have a rig capable of carrying any boozer. Mind you don't overdo the bass or the power. Don't stack 4 to 8 ft from a corner or wall unless you have too much bass in the room and want to get rid of some.

Our wicked guitar playing cousins have a big advantage. Bass frequencies require much more force and amplitude to be heard than guitar frequencies. Try not to get involved with 100W 4x12 guitards. They know not what they are doing.

[Meddle]

Originally Posted by vin*tone

Yeah - except the 210's can often handle more than half a 410.

And remember - you don't need to 'match' you rated power handling exactly. If you have a 300 watt head and want to run 2 TC 210's (each rated 400) The TC cabs will handle them just fine. There is no such thing as underpowering a cab. It's only if you exceed the speaker rating where you could run into issues.

The concept of underpowering a cab confuses me. I'm surprised so many people advocate it. Maybe it is a legacy of early amps that burned up regardless of power loading.

The TC cabs I was looking at are the BC210 models. These are only rated at 250 watts, but often bundled with the 500 watt BH500. I don't think TC would market an amp and cab arrangement that would tear up the cab.

With two BC210s you could turn up the BH500 head pretty high without the cabs farting out under excessive power?

[Nev375]

Originally Posted by Meddle

The concept of underpowering a cab confuses me. I'm surprised so many people advocate it. Maybe it is a legacy of early amps that burned up regardless of power loading.

It's a myth created by unscrupulous music store owners to convince musicians that their rig is not quite right so they can sell more amp heads.

[Meddle]

Surely you underpower a cab any time you have the volume set lower than the point where the amp is giving the cab its maximum power?

[Downunderwonder]

Now you're opening multiple cans of worms.

TC power ratings are fabricated. Overpowering kills.

Underpowering is really overpowering. When overdriving an amp in quest for more volume it makes a lot more power but it's distorted.

Most 500w amps can handily beat up two 250W cabs if you let them.

[Meddle]

I will close those cans then!

Why would a 500 watt amp beat up the two cabs? Surely the 500 watts is split equally between the two cabs (assuming they have the same resistance?).

[Mr. Foxen]

Resistance isn't relevant to cabs. Its all AC unless your amp is broken, so it is impedance. Impedance varies with frequency, so a single number of ohms for impedance will always be a lie. The lie becomes apparent when your cab breaks because you didn't listen to the sound and believed the numbers.

[Meddle]

Originally Posted by Mr. Foxen

Resistance isn't relevant to cabs. Its all AC unless your amp is broken, so it is impedance. Impedance varies with frequency, so a single number of ohms for impedance will always be a lie. The lie becomes apparent when your cab breaks because you didn't listen to the sound and believed the numbers.

When I said resistance I meant impedance, as you indicate.

I've read many times that one should trust one's ears, and if the amp sounds like it is farting out then it will be doing so, regardless of the stated impedance or stated handling capacity.

Presumably a 300 watt amp driving two 250 watt cabs would pose less of a 'threat' to the cabinets? I presume also that a sub-octave pedal or a highly resonant synth patch, or square-wave synth patch would also pose a risk at much lower volumes.

[Downunderwonder]

The numbers are more or less lies told to sell gear.

The usual assumption with a cab rating is it is a thermal rating and given a "normal" bass sound the cab will begin to distort at around half that amount of amp power.

Most of the time we don't actually use a fraction of the rated power of an amp. But when we really lay into a note we can easily briefly get double the rated power out of a normal amp. An overrated TC amp is giving its all at its rated power. A lot of class D don't get a whole lot more than RMS power.

You're dead right about effect pedals and sub lows but also regular lows can do the cone creasing trick just fine.

[Nev375]

The numbers will get you in the ballpark of a theoretically matched amp and cab. But they are only as accurate as the competency and honesty of the manufacturer. When turning up the volume or stomping on pedals listen very carefully for noises your rig does not make at lower volumes.

Since this is something I do anyway all the time, I always use an amp that is overpowered for my speaker(s) It gives me plenty of headroom for a clean signal and if I ever hear anything distorted, I know it's the speaker and not the amp clipping.

It's not like your speakers get one watt too many and then suddenly go boom. They give you plenty of warning before they fail. So always have them in a situation where you can hear whats going on. (i.e. not playing with a couple of guitarists with full marshall stacks who thinks the loudest guy wins.)

[BassmanPaul]

the pair of 2x10s is a versatile solution that I endorse heartily. In a vertical stack you get better dispersion and the speakers are closer to your ears so you can hear them better. Once I tried my cabinets that way I never went back. My avatar shows two of mine on the floor at the side of the stage - it WAS a small stage.

[arai]

Originally Posted by Meddle

The concept of underpowering a cab confuses me. I'm surprised so many people advocate it. Maybe it is a legacy of early amps that burned up regardless of power loading.

The TC cabs I was looking at are the BC210 models. These are only rated at 250 watts, but often bundled with the 500 watt BH500. I don't think TC would market an amp and cab arrangement that would tear up the cab.

With two BC210s you could turn up the BH500 head pretty high without the cabs farting out under excessive power?

With solid state amps the watts it produces goes down as the cabinets ohms go up.
So for example a 500(4 ohm min) watt head into a 4 ohm cab will give you 500 watts. if you plugged an 8 ohm cab in it will only get around 300 watts.
Those bc210s are probably 8 ohms which would allow you to use another bc210 in combination which will give you 4 ohms

[Jazzdogg]

Wattage ratings for bass cabs are usually overstated rubbish, and best ignored.

[Spaldo]

Actually you CAN underpower a cab. That is, you can ruin a speaker by using, say, a 150w head into a 300 watt driver. When you start running your head to its limit in a loud situation, you start feeding 'clipped', square waves into the driver, which can wear out a driver just as quick as if you fed an OVER-powered head into the same box. I know, I've done it!

[Downunderwonder]

Square waves are harmless, guitar players prove this with their clipped to hell distortions, too much power isn't.

[JimmyM]

Originally Posted by Spaldo

Actually you CAN underpower a cab. That is, you can ruin a speaker by using, say, a 150w head into a 300 watt driver. When you start running your head to its limit in a loud situation, you start feeding 'clipped', square waves into the driver, which can wear out a driver just as quick as if you fed an OVER-powered head into the same box. I know, I've done it!

Actually what you did was give your cab way more than 150w. The 150w number is the RMS number. That is supposed to be the wattage that it stays clean within a certain percentage of total harmonic distortion. I say "supposed to be" because people disagree if it's meaningful or not, but that's neither here nor there for this discussion...just trying to put out the fire before it starts.

Beyond the RMS wattage, you've got peak wattage. A 150w amp can put out twice or more of its rating in peak power. So that's 300w or more on its peaks when you crank it super hard. THAT is what blew your cab, not square waves.

[SactoBass]

Originally Posted by JimmyM

A 150w amp can put out twice or more of its rating in peak power. So that's 300w or more on its peaks when you crank it super hard. THAT is what blew your cab, not square waves.

Correct! And that 300 watt driver that Spaldo referenced was probably the thermal rating which means the mechanical rating was likely in the 150 watt range. So, the peak hit from the amp far exceeded the driver's mechanical limits. Poof...there goes the speaker.