Quick ohm/amp cab question.

[bubinga5]

So I may be getting a new amp and cab. The amp is 440 watts at 4ohms. The cab is 300w at 4ohms. I will get 300w right.?

Edited December 18, 2021 by bubinga5

[Downunderwonder]

There's an awful lot more to it than that but, yeah.

 

If you turn it up and it doesn't hardly get any louder the best thing to do is turn it back down a tad and accept that is your lot.

 

Choosing a 4 ohm cab ''to get all the power out of the amp'' is often non optimal. It may pay to investigate further before you blow up a cab that is too small for you.

 

 

[Sparky Mark]

No. If the cab is 4 ohms the amp is capable of delivering 440 watts into it if you increase the amp's output control enough. Just be careful and listen for the cab farting out as you increase the volume.

[chris_b]

What cab is it?

 

If the cab is rated at 300 watts I'd wouldn't expect to get more than 200 watts of clean sound out of it. Probably less, depending on what cab and drivers there are.

 

Depending on your band, 200 watts could easily be enough.

[Dan Dare]

Most drivers can tolerate occasional short term peaks that are higher than their rated input power. Most amps are rated according to how much power they can deliver in short bursts (think milliseconds) at a particular frequency. Their continuous power delivery will be lower, often considerably so. The disparity between your amp and cab is not enormous. I wouldn't worry about it. You'll know if the speaker is struggling because it will not sound pleasant. If that happens, turn down.

Edited December 18, 2021 by Dan Dare

[Sparky Mark]

7 minutes ago, Dan Dare said:

Most amps are rated according to how much power they can deliver in short bursts (think milliseconds) at a particular frequency. Their continuous power delivery will be lower, often considerably so.

I respectfully disagree. Most reputable amplifier manufacturers publish RMS continuous power ratings for their products. Behringer is famous for using Peak outputs but it is in the minority. 

[Dan Dare]

2 hours ago, Sparky Mark said:

I respectfully disagree. Most reputable amplifier manufacturers publish RMS continuous power ratings for their products. Behringer is famous for using Peak outputs but it is in the minority. 

 

Have a look at the qualifying statement with the headline figure. It will usually say something along the lines of "400w into 8 ohms at 1khz for xx amount of time".

 

Wattage ratings are pretty inexact, but manufacturers and consumers need some sort of yardstick. Wattage is easy to understand, so watts it is.

[bubinga5]

4 hours ago, chris_b said:

What cab is it?

 

If the cab is rated at 300 watts I'd wouldn't expect to get more than 200 watts of clean sound out of it. Probably less, depending on what cab and drivers there are.

 

Depending on your band, 200 watts could easily be enough.

Its a Glockenklang Uno 115 Chris. The amp is a Glock Soul. 

[bubinga5]

Im not going to be playing loud atm. I may get a Glock duo or another bigger amp for the amps full capacity. 

[chris_b]

The Glockenklang web site rates this cab as 8 ohms and 300 watts.

 

If that's right, then your amp is 250 watts into 8 ohms, so you'll be fine. Another cab will push the amp to 440 watts into a cab  total of 600 watts at 4 ohms.

 

In either case, unless you go really mad with booster pedals, I don't see how you could damage the cab.

Edited December 18, 2021 by chris_b

[bubinga5]

29 minutes ago, chris_b said:

The Glockenklang web site rates this cab as 8 ohms and 300 watts.

 

If that's right, then your amp is 250 watts into 8 ohms, so you'll be fine. Another cab will push the amp to 440 watts into a cab  total of 600 watts at 4 ohms.

 

In either case, unless you go really mad with booster pedals, I don't see how you could damage the cab.

Ah ok. So the output will stay at 250w with the Glock 115. I thought i could get the full 300w because the cab can take 300w.

[chris_b]

17 minutes ago, bubinga5 said:

Ah ok. So the output will stay at 250w with the Glock 115. I thought i could get the full 300w because the cab can take 300w.

 

I've assumed the cab is the 8 ohms version. Can you confirm that?

 

If the cab is the 4 ohm model you will be able to pump 440 watts into it, which might not be good. I rarely push my 500 watt amps past 12 o'clock, I'm assuming you won't either. In that case you'll be putting approx 250 watts into your 115 which should be fine no matter which version it is.

Edited December 18, 2021 by chris_b

[chris_b]

another bloody double post!!

Edited December 18, 2021 by chris_b

[bubinga5]

51 minutes ago, chris_b said:

 

I've assumed the cab is the 8 ohms version. Can you confirm that?

 

If the cab is the 4 ohm model you will be able to pump 440 watts into it, which might not be good. I rarely push my 500 watt amps past 12 o'clock, I'm assuming you won't either. In that case you'll be putting approx 250 watts into your 115 which should be fine no matter which version it is.

No mate its the 4 ohm version. So a lower volume cab i guess. Thats ok though. I dont the full 440 atm. Ive been assured the Glock will sound awsome with my Atelier.!!

[Downunderwonder]

1 hour ago, bubinga5 said:

No mate its the 4 ohm version. So a lower volume cab i guess.

No. With a tiny amp a 4ohm one will get a little louder than the 8 ohm version.

 

Also, good amp ratings are for clean power. Most will do bursts that will take out a cab if you let them. 

[itu]

I have a Soul amp, too. It used to be in a Soul Combo, but the set weighs a lot. I bought a 2 x 12" cab and put the amp to a carry on rack case. To me that 440 W is enough; I play in band with 13 players/singers. I think the Soul is loud enough, and one very good sounding unit it is. I would not worry about the power. Power is not the same as loudness.

[Bunion]

Get 2 8ohm cabs you then have a smaller practice/rehearsal/coffee shop setup with one cab and for those glory balls to the wall gigs you can break out the stack and go medieval on their a.s.s

 

Bag end cabs are old school heavy but they can take some power

Edited December 18, 2021 by Bunion

[chris_b]

9 hours ago, bubinga5 said:

No mate its the 4 ohm version. So a lower volume cab i guess. Thats ok though. I dont the full 440 atm. Ive been assured the Glock will sound awsome with my Atelier.!!

 

Ah. OK, so the master anywhere up to about 2 o'clock should be safe. I reckon the sound will make you proud.

[bubinga5]

Thanks for the info guys.

[BassmanPaul]

18 hours ago, chris_b said:

 

Ah. OK, so the master anywhere up to about 2 o'clock should be safe. I reckon the sound will make you proud.

Err. The position of the master has no bearing on the maximum volume produced. That depends on the size of the input signal.

 

A 400W @ 4Ω amplifier connected to a 300W @ 4Ω cabinet is still able to produce it's 400W into that cabinet.

[Bill Fitzmaurice]

Pushed to clipping it can probably deliver 800w into that cab. Amps are rated at low THD. At high THD they can easily deliver twice their rated power, if not more.

[chris_b]

3 hours ago, BassmanPaul said:

A 400W @ 4Ω amplifier connected to a 300W @ 4Ω cabinet is still able to produce it's 400W into that cabinet.

 

With the volume controls between 12 o'clock and 2 o'clock?

[Downunderwonder]

27 minutes ago, chris_b said:

 

With the volume controls between 12 o'clock and 2 o'clock?

Usually it depends on the amp's preamp. Master 'output' being an attenuator only, cranking up on the preamp gains blasts on through the master.

[Chienmortbb]

According to Infineum

 

"All the power ratings are at clipping power (THD+N = 1 %). To estimate power ratings at
THD+N=10%, multiply them by 1.33"

 

With a square wave output it goes to 1.414

[Sparky Mark]

The bottom line is that an amplifier capable of delivering 440 watts at 4 ohms (possibly 800 watts peak) is capable of damaging a 4 ohm cab with a thermal rating of 300 watts if you ignore signs of the speaker being driven too hard.