450 watt amp into a 300 watt cab - Yes or no?

[Osiris]

I appreciate that the topic of what amp and cab wattages to match up has been covered many times already, but I still find the whole thing a bit confusing, so I'm asking a very specific question.

I'm looking to pick up a spare amp to use as a back up, and the one I have my eye on (used, in the classifieds) puts out 450 watts at 8 ohms. My main 4 ohm 2x12 cab will handle this no problem, but I have a 1x12 Mesa Walkabout Scout cab that is rated at 300 watts at 8 ohm that I use for rehearsals and small gigs. If I was to buy the amp, would it be OK to pair it with the Mesa cab and run it at sensible volumes i.e. the master volume at no more than noon, quite probably lower? For info, my current spare amp puts out 450 watts at 4 ohms and I never need to run that much above about 10 o'clock on the master volume, but as the amps are from different manufacturers then this is probably like comparing apples and oranges!

I'm not that technically minded when it comes to these things and I don't claim to understand the physics behind it all, so the more simple the answer the better

[Dan Dare]

No problem. Many amps are rated at peak power - i.e. the wattage they can deliver for a few milliseconds - and most good quality speakers can handle well over their rated power for short bursts (I'd say your Mesa will - they use decent drivers). Provided you don't go mad, you should be fine. The speaker will protest if it's under strain, so you'll get an audible warning before any damage is done (always assuming the drummer/guitarist isn't deafening you to the extent that you can't hear it...).

[Lozz196]

Take it easy on the lows, and use your ears, you should be fine.

[Al Krow]

Or you could sell the Mesa 1x12 cab and get a second hand BF1x12 that can handle 600W without breaking into a sweat (and maybe even have some change to fund your purchase of the new amp)?

[Phil Starr]

A 400W amp turned down noticeably is a 200W amp. The only problem is noticing.

Most speakers can handle the power from an amp for a long time before overheating, the real problem is more likely to happen in the low frequencies where speakers have problems with being pushed too far. It's just the deep bass that does that so listen to advice about watching your lows. Roll off the bass a little and certainly avoid bass boost including from any fx and you'll be fine.

[Osiris]

Thanks everyone for the helpful replies.

The Mesa cab has a built in passive speaker thingy (not sure of the correct term, but it seems to be essentially a cone without a magnet) that fires out of the bottom that, as I understand it, helps to increase the bass response of the cab anyway. It certainly has good deal of low end for a small cab. So I've never yet been in a situation where I have needed to boost the low end EQ. If anything, I prefer a tone that focuses on the mid range to help cut through the mix so backing off the low end shouldn't be a problem if the cab starts complaining.

But yes, I'll be keeping things under control, I'm a bit too long in the tooth to be running everything flat out! And I have the bigger 2x12 cab for the occasions where more volume and low end is required too. I don't tend to use effects live other than a touch of compression so that shouldn't introduce any additional low end - if anything it should help ease the strain on the speaker, I believe.

Edited June 29, 2017 by Osiris

[Osiris]

[quote name='Al Krow' timestamp='1498733033' post='3326621']
Or you could sell the Mesa 1x12 cab and get a second hand BF1x12 that can handle 600W without breaking into a sweat (and maybe even have some change to fund your purchase of the new amp)?
[/quote]

Don't tempt me with any more new toys that I probably don't need in the first place

[markstuk]

If the amp you're looking at puts out 450W into 4 Ohms, it will probably only output 300W into an 8 Ohm load anyway.. Check the specs of the amp in question..

[Osiris]

[quote name='markstuk' timestamp='1498738025' post='3326698']
If the amp you're looking at puts out 450W into 4 Ohms, it will probably only output 300W into an 8 Ohm load anyway.. Check the specs of the amp in question..
[/quote]

The one I'm looking at puts out 800 watts at 4 ohms and 450 at 8 ohms according to the manufacturers specs online.
My current spare amp puts out 450 watts at 4 ohms and around 300 at 8 ohms. Apologies for the confusion!

The amp I'm thinking of getting is something small and easy to cart about which is the main attraction, but I want to be sure that it isn't going to be too overpowered that it could potentially damage the Mesa cab before opening my wallet. From what the guys are saying above, it'll be fine as long as everything is kept under control - which it will be

[Bill Fitzmaurice]

[quote name='Osiris' timestamp='1498738725' post='3326717'] I want to be sure that it isn't going to be too overpowered that it could potentially damage the Mesa cab before opening my wallet.
[/quote]Does it come equipped with a volume knob? If so no worries.

[Osiris]

[quote name='Bill Fitzmaurice' timestamp='1498740304' post='3326732']
Does it come equipped with a volume knob? If so no worries.
[/quote]

[Chopthebass]

Its only a matter of time before the BFM wit kicks in.

[HazBeen]

And you could always set your Keeley Pro to hard knee and use it as a limiter to protect against spikes....!

[mcnach]

As others have said... no problem. Just don't go crazy with it, especially boosting lows, and listen for any signs of struggle: if in doubt, turn down a bit. But chances are you won't bother it one bit.

One other thing you might like to consider is a high pass filter of some sort (HPF for short if you search for it). It may not be necessary in many situations, and some amps have one built-in already in fact, but I still often use one. It cuts the lowest lows and lets the rest through. The purpose is to eliminate frequencies that are amplified by the amplifier, and sent to the speakers, which move accordingly, but that don't result in an audible sound for us. Something like the SFX "Thumpinator" has no effect on the sound (some claim it tightens the low a tiny bit), but the speakers work less, and so does the amplifier. That could be helpful to use.
There are variable HPFs, and they can be pretty cool as you can adjust the cut frequency a bit higher into the frequencies we do hear and they can be very useful when your bass sounds a bit boomy/muddy, as it happens on some stages/rooms, to tame the very low bass and as a result get a tighter clearer bass.

I used to use a pair of small TKS S112 cabs a lot, which are rated relatively low, and I used the Thumpinator as an extra level of protection. I noticed that with the Thumpinator, the master volume ended up set a little lower than without it... which I liked and made me feel a bit happier about using them with powerful amplifiers.

Just a thought.

[Osiris]

[quote name='HazBeen' timestamp='1498846553' post='3327572']
And you could always set your Keeley Pro to hard knee and use it as a limiter to protect against spikes....!
[/quote]

I don't own a Keeley Pro but I have a number of other compressors and limiters to choose from [size=4] [/size]

[size=4]Mcnach, good call on an HPF. I'll email the manufacture to ask if the amp in question has one built in as I can find no reference to one in the specs. I've got a Zoom MS-60B and I seem to think that there was a thread recently on that having an HPF in one of its models, I'll have look for the thread to see what was said. I can always run that in front of the amp if its suitable. [/size]

[size=4]It sounds like I should be able to get away using the amp and cab together as long as I don't go mad with it, which I won't be! [/size]

[HazBeen]

Doh! Sorry, wrong signature..... but limiters and also HPF would/could help. But, you can also ensure you keep volume down which works best and is simplest.

[quote name='Osiris' timestamp='1498893299' post='3327770']


I don't own a Keeley Pro but I have a number of other compressors and limiters to choose from [size=4] [/size]

[size=4]Mcnach, good call on an HPF. I'll email the manufacture to ask if the amp in question has one built in as I can find no reference to one in the specs. I've got a Zoom MS-60B and I seem to think that there was a thread recently on that having an HPF in one of its models, I'll have look for the thread to see what was said. I can always run that in front of the amp if its suitable. [/size]

[size=4]It sounds like I should be able to get away using the amp and cab together as long as I don't go mad with it, which I won't be! [/size]
[/quote]

[Jus Lukin]

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Edited February 24, 2022 by Jus Lukin

[mcnach]

[quote name='Osiris' timestamp='1498893299' post='3327770']
I don't own a Keeley Pro but I have a number of other compressors and limiters to choose from

[size=4]Mcnach, good call on an HPF. I'll email the manufacture to ask if the amp in question has one built in as I can find no reference to one in the specs. I've got a Zoom MS-60B and I seem to think that there was a thread recently on that having an HPF in one of its models, I'll have look for the thread to see what was said. I can always run that in front of the amp if its suitable. [/size]

[size=4]It sounds like I should be able to get away using the amp and cab together as long as I don't go mad with it, which I won't be! [/size]
[/quote]

There's also a thread around here somewhere about a variable HPF pedal, based on the "FDeck" one. There's a small company which will build one to order and it was something like 90 quid only, or so... Even if an amp has a fixed HPF, after I discovered the great things a variable one allows you do to to your sound (there's a nice one built in my Mesa D800+) I kind of want to have that as a pedal so that I can use it with any amplifier...
I should find that thread...

[mcnach]

[quote name='Jus Lukin' timestamp='1498901324' post='3327832']
The HPF in the MS-60b can be found on the Ac-BS pre-amp, it's the 'depth' control. I often use two, both otherwise set flat, to stack the filters to -24bd/Oct. Usually one will be low, bringing in the steeper slope, and one higher, rolling off audible bass a little more subtly. Followed by a comp, it's becoming my go-to setup!
[/quote]

There's a variable HPF in the MS-60B??????
And I sold mine????

I think I'm going to have to get another... It's a great pedal with so many different sounds. I sometimes end up needing just one specific effect I do not own, for one song, and that pedal is ideal... I've lost count of how many pedals I've sold and bought again (Multicomp, LS-2, PD7 overdrive, q-tron, boss chorus...)

[Jus Lukin]

-

Edited February 24, 2022 by Jus Lukin

[SisterAbdullahX]

I put 1250 watts through my 600 watt cab, not at anything approaching full volume, obviously. I've yet to see the clip light.

[FinnDave]

Personally, I would never plug an amp into a cab with a potentially higher output than the cab could handle. Any accidental tweaking of the volume knob could be catastrophic.

[xgsjx]

Only if you were very foolish. But then you could have as equally as catastrophic results being foolish if you had a 300w amp plugged into a 400w cab.

[Bill Fitzmaurice]

[quote name='FinnDave' timestamp='1499018391' post='3328632']
Personally, I would never plug an amp into a cab with a potentially higher output than the cab could handle. Any accidental tweaking of the volume knob could be catastrophic.
[/quote]You should get into the ring with a believer in the myth of under-powering, see who wins out.

The fly in your particular ointment has to do with the fact that a volume knob position isn't an indicator of how much power the amp is putting out. That depends on a number of factors, starting with the frequency response and output voltage of the pickups, the gain structure throughout the signal chain, EQ boost or cut, speaker impedance with respect to frequency, and so on. Even with the volume knob dimed one set of circumstances can result in the amp running at perhaps a quarter of its rated output, while another set of circumstances could have the amp clipping with the volume control at noon or less.

There's a lot of wiggle room with respect to what will work. Having the amp rating anywhere between 1/2 and 2x the speaker rating is probably safe.

[FinnDave]

To be honest, Bill. I've never even heard of the 'myth of under powering', though as you describe it as a myth, I won't bother looking it up! I started playing in the 70s, when the accepted standard was a cab rated at double the potential output of the amp. I have learnt to accept a smaller safely margin than that over the years, but would never plug a cab into an amp capable of delivering more power than the cab could handle.