A question of volume?

Compare them in the same space.

 

My guess is the two amps had different EQ and gain settings and that’s what made the big difference, or maybe design, or it’s possible you have week amp.

 

Agreed. Or the PF's volume doesn't kick in all the way. Some amps have a very sensitive volume knob and some don't. If you haven't tried cranking the PF through the cab then I'd say try that, though back off if your speaker starts to complain. If the speaker farts out at too low of a volume you need to add another cab to your rig.

 

Volume knobs, EQ knobs are not calibrated to all work the same from amp to amp.
Turn the knobs differently for each amp.

Not all cabinets are equal in volume. Especially with totally different drivers and designs.

 

Compare them in the store!

 

Fender not past 1/2 way?? On the volume dial? Might it not go much louder even if turned all the way.
Not all volume knobs have near same taper

 

The fender probably has a relatively high cutoff frequency on the high pass filter to get more perceived volume out of it since it's designed to get the most out of the combo format. The Ampeg is designed to work with a variety of speaker cabs. Could also be one is going into 8 ohms and one into 4, which will make a small difference.

 

My bad, just saw it's a Rumble head into a 210. A 210 has more surface area for the drivers than a 115, so depending on the cab design it should be a bit louder.

 

Actually one 15” speaker has more surface area than two 10” speakers.

 

How can the surface area of two 10inch speakers be smaller than the area of one 15inch speaker?

 

PF115 has a lot of low end response and the Rumble does not. The tradeoff for that kind of low end response is reduced comparative volume because it takes more wattage to amplify lows than highs or mids. Swap heads around with the cabs and you will find the PF500 has more volume in the Fender cab and the Fender head has less volume in the Ampeg cab. Physics. Can't do a thing about it.

 

That's all true, but there are some things you could do that might help. Here are my suggestions - some/none/all might be of use:

1. Roll off the low end on your amp (costs nothing)

2. Get one of these - [sfx]:Thumpinator (costs a bit more)

3. Get another PF115 so you've got 500 watts into 4 ohms (costs quite a lot more)

The thing is that if you're sitting a couple of feet in front of the cab in your bedroom you won't be hearing a lot of the LF that it's pumping out - probably more than you want/need - so rolling off a few dB at 40Hz (option 1) is probably going to make quite a difference.

 

Either way it's a moot point. Cone surface area has little bearing on the result. Displacement (T/S spec Vd) does.

+1. OP, google 'equal loudness curve'. Most combos have cabs that are too small for the drivers within, resulting in a response bump in the midbass, which subjectively makes them sound louder. That's realized at the cost of low end output.

 

Speaker size matters when it comes to moving air (SPL) - cone surface area.
# 8” 10” 12” 15” 18”
-----------------------------------------------------
1 50 78 113 176 254
2 100 157 226 353 508
3 150 235 339 530 763
4 201 314 452 706 1017
5 251 392 565 883 1272
6 301 471 678 1060 1526
7 351 549 791 1236 1781
8 402 628 904 1413 2035
NOTE: All numbers rounded down to the nearest inch.

Drivers, enclosures, power, etc all are factors but speaker size does matter when it comes to moving air (SPL) and shouldn’t be downplayed. And remember the cab is built around the speaker and not the other way around.