What Happens If You Put A 100 Watt Valve Amp Into A 30 Watt Cab?

MrBump

Serious question, and I know that the obvious answer will be that the speaker will blow.

I'm wondering if anything will happen at home volumes.  I've got an old 100 watt Orange, and a 5 watt valve practice amp - TBH, the 5 watter is insanely loud.  I'd never have either of them as loud as the 5 watter can go at home.  Does that mean that they're both safe into a 30 watt cab?

Modulus_Amps

The cab doesn't know how much power is available, only what it sees, so if you are confident you can keep the volume level below 30w then it should be fine, saying that 30w clean is not actually super loud, I routinely play at that level in the house so you may be better to put a power resistor in parallel with the speaker to make it a bit safer... or use an attenuator.

AlasdairDavis

I doubt you'd turn your 100 watt amp anywhere near 30 watts for home use! You should be fine. If you blow the speaker you've gone too far

Maynehead

It will only be a problem if you turn up the volume too much. As a rule of thumb if you keep the volume below the maximum that your 5W amp can produce then there should be no problems at all.

xscaramanga

What are the speakers? Celestions tend to be very conservatively rated anyway, which gives you a bit more leeway.

I've never tried a mismatch that bad, but I have run a 100 watt Marshall into a 1x12 Vintage 30 (rated at 70 watts) without incident. You'll hear the speaker flapping and distorting before it actually blows anyway, so just listen carefully and if the speaker starts to flub or fart out, back off.

MrBump

Thanks for the replies, guys - it's a Subzero cheap-as-chips 1x10 cab.  Celestion 10 inch driver, apparently - no idea how it sounds but for £60 I thought I'd take a punt, as I'm always swapping speaker cables over.  I'm not expecting miracles, but I'll let you know how it sounds.

Voxman

I know this is only a suitable approach with certain amp designs, but I just wondered whether taking a couple of power valves out for home use might be an option with your amp?

MrBump

Voxman said:

I know this is only a suitable approach with certain amp designs, but I just wondered whether taking a couple of power valves out for home use might be an option with your amp?

Hi - yeah, it's not so much reducing the power of the Orange - it's actually in the shop having a (fully reversible) power reduction circuit fitted.  This was more about understanding what the actual limits might be, whether there was something other than volume that might shorten the life of the speaker cab.
 
Incidentally, I've run the Orange before in 2xEL34 config before, it really wasn't the same...

ICBM

Pulling two valves is actually a bad idea because it will still leave the amp capable of producing at least 50-60W, and with the slightly thinner tone you're likely to be tempted to turn it up further, even if only a bit.

As already said, as long as you play at less then the maximum volume the 5W amp is capable of - about 10W fully distorted probably - then there's no problem with using either amp.

Sometimes excessive bass can damage a speaker even below its rated power, but you would need to be putting a bass or a full-range PA-type signal through it for that.

cosmiccarrot

I use a marshall 100w SL into a single G12 20w speaker. With an attenuator and a controlled volume you get the right amount of movement on the cone and can actually find the sweet spot easier imo.

MrBump

The Subzero cab arrived a couple of hours ago.  It's actually really, really good - can't see any flaws in the finish, and it sounds incredible.  There's a definite thinner sound coming from it than my usual 2x12, but that's not a bad thing.  The clarity through a clean amp is really great.  Very impressive cab for not much money at all.

Impressed.