Confused on amp heads and cabinets compatibility

[Bef]

So I have just got a Fender Rumble 115 cab and I'm looking at getting a Trace Elliot AH100 GP7 amp head and have just got some questions. Are these two actually compatible and is there anything that I need. I right now have a pukka gc60 amp and I plugged the output into I think the input of the cabinet and I turned the gain to max and it was incredibly quiet borderline inaudible so im not sure what this really means. But really just wanna know if the cab and amp head are compatible? Sorry for rambling 

[Mudpup]

Should be fine. You'll need the correct speaker connection cable. The cab is probably a speakon input - the amp may be a jack output. You shouldn't have an issue finding a jack to speakon lead. Just don't cheap out on it too much.

Edited December 26, 2024 by Mudpup

[Bef]

Thanks sm, very helpful

[bassbiscuits]

Amps will say something on the back about how many watts they put out at how many ohms. Something like 300w/8ohms or 500/4ohms for example. 

 

Similarly the cabinet should say whether it’s 8ohms or 4ohms. 
 

So you just need to make sure that the cabinet / speakers can handle the amount of power they’re receiving from the amp at the corresponding number of ohms. 

So a 300w 8ohm cab would work fine with an amp head that puts out anything up to 300w at 8ohms. 
 

Not sure if that’s what you needed to know. Apologies if it wasn’t, and hope it’s helpful if it was.  

Edited December 26, 2024 by bassbiscuits

[Bef]

That is helpful thanks it’s really quite hard finding just actual answers on google like the ohm and watts compatibility or whatever but i’ll definitely be keeping this in mind 

[tauzero]

Is that the Pukka Ohm GC60 combo that you're using, and if so, is the output that you're using the one on the front panel that says "Pre-amp Output"? If so, it's really quiet because that output is intended to go into a second amplifier rather than a cab. @TheGreek has owned a couple of them, he might be able to give some pointers if he hasn't completely forgotten them by now.

[Suburban Man]

Looking at the spec of the Fender it is an 8 ohm cabinet rated at 300Watts continuous output, so fine to plug into the Trace Elliott head.  However you might find that you don't get a huge amount of power, since the AH100 appears to give its full output into 4 ohms, so you may only get half the rated power out of it when plugged into an 8 ohm cab (I couldn't find a definitive spec for the AH100 but if I'm right that would be 50Watts RMS)

 

like Bassbiscuits says: 

Amps will say something on the back about how many watts they put out at how many ohms. Something like 300w/8ohms or 500/4ohms for example. 

 

Similarly the cabinet should say whether it’s 8ohms or 4ohms. 

 

Only problem nowadays is that so many manufacturers quote 'peak' or 'instantaneous' power that the RMS output - which is the useful figure for both amps and speakers - seems to get left out of the marketing blurb

[Downunderwonder]

Is this Peavey rehash or a vintage SM??

 

I don't recall a 100 in either. The vintage sm1000 was an absolute beast and rare.

Edited December 27, 2024 by Downunderwonder

[Mudpup]

8 hours ago, Suburban Man said:

Looking at the spec of the Fender it is an 8 ohm cabinet rated at 300Watts continuous output, so fine to plug into the Trace Elliott head.  However you might find that you don't get a huge amount of power, since the AH100 appears to give its full output into 4 ohms, so you may only get half the rated power out of it when plugged into an 8 ohm cab (I couldn't find a definitive spec for the AH100 but if I'm right that would be 50Watts RMS)

Remember it will be older Trace Elliott watts though....handle with care!

[TimR]

Don't worry too much about watts. Trust your ears and listen for distortion.

 

If the cab can handle more watts that the amp can deliver then at worst you run the risk of pushing the amp into distortion which can overheat the speaker. 

 

If the cab can't handle the power the amp is delivering then you'll get the speaker hitting the mechanical limits and you'll destroy it that way.

 

In any case, trying to match cabs and amps is very hard, if something is in your budget, and you like what they sound like together, then really that's going to determine what you purchase. 

 

Can you try them together before you buy so you can hear what they sound like? 

[Mykesbass]

15 hours ago, tauzero said:

Is that the Pukka Ohm GC60 combo that you're using, and if so, is the output that you're using the one on the front panel that says "Pre-amp Output"? If so, it's really quiet because that output is intended to go into a second amplifier rather than a cab. @TheGreek has owned a couple of them, he might be able to give some pointers if he hasn't completely forgotten them by now.

Looks like Tauzero has hit the nail on the head here. It is amazing how few combos have a speaker output. 

[TheGreek]

17 hours ago, tauzero said:

Is that the Pukka Ohm GC60 combo that you're using, and if so, is the output that you're using the one on the front panel that says "Pre-amp Output"? If so, it's really quiet because that output is intended to go into a second amplifier rather than a cab. @TheGreek has owned a couple of them, he might be able to give some pointers if he hasn't completely forgotten them by now.

 

I've had two of the Ohm Pukka combos - nice combos - but aren't they 16 ohm units??

 

I plugged one into a 4ohm pa speaker with similar results  - no volume - I assume it was because of the low output amp.

[asingardenof]

20 hours ago, bassbiscuits said:

So a 300w 8ohm cab would work fine with an amp head that puts out anything up to 300w at 8ohms.

 

It'll probably be OK with an amp more powerful than 300W as well, because the likelihood of the SNP putting out its maximum output is low. My 500W cab does OK with a 600W head, for example.

[TimR]

1 hour ago, TheGreek said:

 

I've had two of the Ohm Pukka combos - nice combos - but aren't they 16 ohm units??

 

I plugged one into a 4ohm pa speaker with similar results  - no volume - I assume it was because of the low output amp.

 

I think it would be the other way round. Higher impedance would require more power to drive for the same displacement.

 

Maybe the amp is just undersized. Is the combo a sealed cab? Maybe it has a more sensitive speaker.