A question of volume?

[Wes Whitmore]

Unless you can prove that something is actually wrong with your amp, I will have to say that the volume taper of the ampegs doesn't allow these things to get rocking until way past half way up on the knob. Also, the gain setting of this amp really needs to be tweaked because it will allow you to turn the level down to nothing, or up to clipping. This is what drives the final master volume. You should set the gain as hot as you can without it clipping, and that will give you more signal to amplify. Even after that, I'm at 2 or 3 o'clock compared to 9 or 10 o'clock on my GKs. It's loud there though. That amp should be getting plenty loud for you.

 

[BurningSkies]

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.

See below:

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.

In itself, speaker area does not guarantee loudness. What does is Vd, or Volume of Displacement combined WITH speaker area. Because, while a speaker or multiple speakers may have a lot of real estate, if they don't have a enough effective travel (xmax), they're not pushing much air.

You need both to be loud, and xmax is certainly more effective when you want to be low.

 

[Joe Louvar]

My math shows the surface area of a 15" circle would be smaller than the surface area of two 10 circles. Pi • r² = 113.097" = 15" circle and 157.079" = 2x10" circles.

Now speakers are cones not circles, but I would need a few more numbers for that... and a lot more concentration.

How to calculate cone area.
Cone area = pi x (r x r)
pi = 3.14 r = radius of sub

Two 10" = 157.08
One 15" = 176.71

 

[billyfalconer]

My math shows the surface area of a 15" circle would be smaller than the surface area of two 10 circles. Pi • r² = 113.097" = 15" circle and 157.079" = 2x10" circles.

Now speakers are cones not circles, but I would need a few more numbers for that... and a lot more concentration.

Looks like you were multiplying diameters and not radii, which are half the diameters.

10" speakers:
3.1415 * 5" squared
3.1415 * 25" = 78.54
2 * 78.54" = 157 square inches

15" speaker
3.1415 * 7.5" squared
3.1415 * 56.25" = 176.7 sq inches

 

[coyote1]

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.

Incorrect. Surface area of 2x10" is @ 157 sq inches; 15" is 176 sq inches. EDIT: I see others have already done the math for you.

Back to the thread topic: IMO this is why mail order is not an adequate replacement for brick-and-mortar shops. How many amps will you order and then send back before you stumble on the right one? You need to hear them in real life to get a clue as to whether it can work. And therefore, I often make the purchase at the store - even though mail/internet might be a few bucks cheaper. It is in my self-interest to help them stay in business.

 

[Joe Louvar]

+1 Skies - everything matters.

 

[seamonkey]

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.

It's a waste of time, the above table means nothing because not enough information on the drivers is given. e.g. If you buy a home stereo 10" speaker you will blow the hell out of it before it even approaches output you can get from a pro-driver 10" speaker.

BTW - It's a piston, "cone" area versus "circle" area is no difference.

 

[will33]

It seems a lot of people stop at area when they need to be worried about displacement when figuring this stuff. Your cone could be as big as a house, but if it doesn't move back and forth, it displaces no air.

 

[Joe Louvar]

^^^ +1 Will. Everything is important. If your cone is the size of a dime no matter how much it moves back and forth its not going to move much air either.

 

[timber22]

I had a PF500 / PF115 rig. It definitely gets pretty loud, but you have to turn up the gain and volume pretty high to get it there. As has been said earlier in this thread, some amps seem to be designed to hit a high volume with the knobs fairly low and then they reach their limits shortly after that. The Ampeg doesn't seem to work that way. Also, I liked the tone with the low boost button engaged, but it's significantly "louder" (more mids, less bass) with the button disengaged.

 

[will33]

^^^ +1 Will. Everything is important. If your cone is the size of a dime no matter how much it moves back and forth its not going to move much air either.

Also true.

 

[Square]

How to calculate cone area.
Cone area = pi x (r x r)
pi = 3.14 r = radius of sub

Two 10" = 157.08
One 15" = 176.71

Ha! looks like I got the 10" calcs correct then lost my sanity somewhere in the 15" math... Thanks for keeping me straight. Displacement, I see that would make all the difference and I suppose for that it's surface area and travel. I really was not looking to get this technical but that's okay I appreciate everyone's responses.

I wish my Brick and Mortars had this stuff in stock. California now requires that sales tax be charged on anything being shipped into the state so there is not much, if any, advantage to ordering online. I envy you guys in the big metro areas.


Thnx again

 

[seamonkey]

Example of a single 12" far outperforming an 8x10

A 1" driver in a headphone may far underperform a much smaller one designed for IEM.

 

[Joe Louvar]

Ha! looks like I got the 10" calcs correct then lost my sanity somewhere in the 15" math... Thanks for keeping me straight. Displacement, I see that would make all the difference and I suppose for that it's surface area and travel. I really was not looking to get this technical but that's okay I appreciate everyone's responses.

I wish my Brick and Mortars had this stuff in stock. California now requires that sales tax be charged on anything being shipped into the state so there is not much, if any, advantage to ordering online. I envy you guys in the big metro areas.


Thnx again

Your welcome, and I hear ya about the tax. BTW, I see you live in Fresno, my good old friend Richie Blue (guitarist/singer) plays the clubs, etc there a lot - if you see him, tell him I told you to say hello. Take care bro.

 

[Russell L]

Just for comparison, my Markbass Little Mark III and Traveler 151P cab are plenty loud for most gigs (300w with 1x15). In the living room I was afraid they wouldn't be, but when I set up at a gig I find that they are much louder than I thought. I mostly run with the gain at 2:00 and the VLE filter at around noon (rolls off some highs), maybe a low mid boost just a hair once in awhile. Sometimes I cut the high mids just a tad as well. The master volume usually ends up at 10-11:00. With dual 151P cabs the volume is awesome (500w with 2x15).

 

[JimmyM]

Example of a single 12" far outperforming an 8x10

A 1" driver in a headphone may far underperform a much smaller one designed for IEM.

Deopends on your definition of outperforming, doesn't it?

 

[wcriley]

Also a little unfair to compare a PA sub cab to a MI cab.
I see his point, though, as regards driver size/displacement.

 

[CL400Peavey]

Deopends on your definition of outperforming, doesn't it?

It sure does. That graph looks like 1w/m frequency response, or something similar. I cant imagine that an 810 only gets that loud. There will be trade off in every cabinet. Weight, size, number of drivers, frequency response, total SPL, the list goes on.

as an example, full range drivers are only going to extend so far one way or another when it comes to frequency response. The cab design will help, but then you are possible getting into a bigger cab, more weight. You will also run into a max SPL. So you may end up with a cab that has better low end response, but you suffer in total SPL or sensitivity. You may end up with a cab that has great mid range response, and spl, but suffers on the lower end, and is not present on the upper end. You may have to end up using non full range drivers and a cross over. The most important thing is most of this boils down to personal preference.

JimmyM loves a sealed Ampeg cab. No amount (no reasonable amount) of love or money is going to get him away from that sound. Its not that its a bad sound, its just what he prefers. Its not my sound, so I use a different kind of cab. His cabs do their thing and give him the tone he wants, my cabs do their thing and give me the tone I want. If some day Jimmy comes to the conclusion that he wants something else tonally he might look at different cabs, and change it up. I dont think that is likely, but it doenst mean any of the cabs are better or worse as long as you take them in context of what they are.

Now If Ampeg was claiming that their sealed 810 was the lowest tuned cab on the market I would call BS. Same if they claimed that it was the loudest, or the lightest, or that it met everyones tonal goals. None of these are true. What they can claim, and is very important, is that the Ampeg cab has that "sound" that a lot of people hear in their heads, it solves a lot of peoples tonal quests. So in that sense, for some, that cab sounds best. If someone was looking for a cab that weighs less than 40 pounds, and can be cleanly driven to huge SPL levels, the 810 wouldnt be it. But a can that does meet those criteria isnt going to sound like an ampeg either.

 

[dspellman]

My math shows the surface area of a 15" circle would be smaller than the surface area of two 10 circles. Pi • r² = 113.097" = 15" circle and 157.079" = 2x10" circles.

Now speakers are cones not circles, but I would need a few more numbers for that... and a lot more concentration.

A 15" speaker actually has a cone diameter of about 13" - 13.2" (don't forget the amount of space the surrounds take up)
A 10" speaker around 8.2".

So actual swept area would be 134.7" for the 15" speaker and 105.6" for the pair of 10" speakers. Put another way, a 15" speaker is equivalent to around 2.5 x 10" speakers.

 

[oldcatfish]

Watts are a bit subjective with amp makers. And there are many variables to perceived volume that were already mentioned...speaker surface area and efficiency, eq voicing of the amp, and even location---if the Fender was up against a wall but the Ampeg was in the middle of the room, etc.

That being said, Fender Rumble amps get a lot louder at their rated watts than a lot of other brands.