Ampeg 1540 15" Replacement

Notes:

1. If I am understanding correctly, you are running a bi-amped rig with bass going to the bottom 4x10 section and highs going to the upper 4x10 section. Is that correct?
2. Assuming that is the case, why would you want to do that? If bass frequencies are what you're after, then keep in mind that you removed quite a bit of your bass response potential when you cut the lows from the upper 4x10.
3. Did you model the Deltalite speakers with the cabinet to make sure that the cabinet provides adequate cubic footage and porting for the drivers to operate correctly for your needs?
4. When comparing your DIY 4x10 solution to the SVT-1540: "Getting more low end" is usually more complex than just comparing drivers' frequency responses. Other considerations include cabinet size, porting, cabinet location (eg. near a wall, near a corner, at ear-level, etc.), room characteristics, amplifier (eg. Available power, EQ, etc.), effects, and instruments. There are probably more considerations that I'm forgetting.

 

If the cab internal volume and tuning were known the Delta 15LFA could be modeled. Otherwise, the only way to tell would be to try it. Below about 600 Hz, the Delta 15 LFA has a sensitivity of only 96 db/w/m, so would likely have difficulty keeping up with multiple 10's. Also, it has only an average amount of linear excursion (4.8 mm). It would likely not significantly outperform the four Deltalite II 2510's.

As pointed out by Warpeg, cutting bass from the upper four 10's may not have helped your quest for more low end. If you noticed an improvement with the Deltalites then they are likely working adequately (if not optimally) in that cab. You might consider replacing the remaining upper four 10's with Deltalites and running the cab as an 810.

 

The original 1540 15" driver I assume is a cast frame eminence vs the delta LF.... if the delta is stamped basket then my gut tells me it wouldn't compare to the original driver.

I've heard a few 1540 cabs and they sounded great but I feel an 810 (ran fullrange) sounds even better

 

I'll try not to be negative.

1540s freaking suck
They don't make " more bass" than a 810
They make less

Ampeg uses a cast frame legend.
Eminence CB158
3.6 cubic feet tuned to 40hz

Also have used stamp steel Eminence
Special design. Similar to Beta 15 and closer to the older Gamma 15. Don't matter they sound the same and suck against a 410

Also , did I mention? 1540s suck lol.

This coming from a guy that has exclusively used Ampeg 810s 20 plus years.

Your talking .9 cubic feet per driver x 8
In sealed cabinet.
Only way get more bass from the thing is run all matching factory drivers. Technically the air space is to small for that driver . you get the classic sounding bloom which is a big 100 hz peak from the airspace being to small. Multiple by 8 and bingo. Bass

Realistically I'd just cut 100 hz and boost 60 and 80 hz. And basically use 2 cabs and over EQ the krap outta it.

Otherwise after years of playing them. I just used normal EQ and was fine with it.

 

Single 15 at 96dB will not do a thing up against say 100 to 106 dB of 10" speakers.

10x power to even get 3dB.
LFA will be toast and inaudible even before it gets halfway there.

I've bounced back n forth between ported 2x15 and sealed 810

And it's basically a 4x15 to get same SPL as a 810.

I liked my 4x15 ported setup. But I wasn't gonna carry 4 cabinets on the trailer.
So it was easier to run 2 810s on tour.

Anyhoo in your situation up against 12 x10" drivers.
I'd say it's at least high power 2x15 and plenty of watts. Technically it be more like 4x15 or 6x15

Weird huh.


I Added a third 810 and another head and fully cranked it really didn't get louder. I knew it was on. But it just inaudible.
You have to double speaker area to gain 3dB so up against 2 x 810 technically I needed 2 more cabs to make a slight difference.

 

The over EQ trick is simple lol.

But is what it is.
I pretty familiar with the spongy spot of a 810
And .9 cubic feet will always be that. No matter what driver is in there

I'd say with those Delta's you have.
If you did have a cab. Fully loaded with 8x those. And used that as your dedicated
Bass" cabinet.

It could work...ish they just have slightly more overhead. And it's just alot more dedicated cone area to bass. Definitely alot more sensitivity. And kick a stock 810s booty.

Or spend the money on just pair 2x15 ported cabs. Or pair of old school Acoustic 408s lol
Is 8x15 enough

I've done the whole 2 different heads or 3 heads and yes of course some with distortion some not.

Likewise used 810 and 1x18 and mixes of all kinds of cabinets.

Fun as it was. I found running 2 cabs and 2 svt heads. Was way way more consistent.

At first I did have fun Making EQ slightly different on both heads. And likewise use combination of different distortion / fuzz etc.

But eventually found using one head as the master. And just slave the other head. Basically making EQ and Volume control exactly the same with the master. The other was just a power amp.

Even that wasn't necessary. But the 2 ohm taps on my classics just seemed spongy. Liked 4 ohm tap better.
Likewise cooked 2 heads running 2 ohm taps. Shouldn't make a difference with tube heads.
It was just coincidence that I cooked the screen resistors on one and few tubes on the other on 2 ohm taps.

Had a backup SVT but that died too.
Got really sick of finding repair places on tours. And when the backup for your backup dies lol. Just wanna die

Anyhoo blah blah

Sound and tone and everything seemed much more consistent with just master/slave head. And 16 matching drivers. That was the point.
If I wanted to do a different head / different EQ thing. I'd probably still just use same 2 cabs for both , all same drivers

 

I'd say not worry to much about " deep" bass.
Smaller club shows it was amazing.
But for the most part, the super bass I did hoax outta it. Was just fun for me on stage.

In a metal/ industrial band
Up against real drums, sampled drums and bass heavy synth parts

Only thing that put me in the mix was just not using pedal distortion. And racking the heads into a grind.

But I almost miss running one head clean.
Then the other head I slightly shifted the mid settings. And got a evil growl with a Maestro Bass Brass Master.
That's what put me in the mix, likewise just 2 grindy heads slaved.

 

I own and use a 1540he paired with an SVT-VR and the 15 inch does put out more low end; you can feel it. The top portion is the same sealed 4x10 as either top or bottom of an 8x10, but the bottom is ported and can go as low as 28hz whereas the 8x10’s usable is 40 hz as they advertise. Believe me, you can hear and feel it, especially further away from the stage. Bottom line, you wouldn’t have to change the 15 to get really low end.