Speaker cab / combo project: driver choice

[Lia_G]

Hey folks,

I'm embarking on a bit of a project. I have the box from an Eden CXC110 combo:
[Invalid or Expired Link Removed]

It weighs 50 pounds with the WT330 head, not the 39 pounds that they advertise. I'm planning on making a lightweight combo out of this, using a different head and speaker. The Eden coax speaker is blown, plus it's a boat anchor ... it must weigh 15 or 16 pounds or so. Once the WT330 and the speaker are out, it's fairly lightweight. I'll add a Markbass LMII, or one of the upcoming Genz Benz Shuttle heads, and a neo 10 or 12, and I should have a combo that weighs in around the 30 to 35 pound range total.

I calculated the internal volume (42 litres), and plugged the parameters for a couple of Eminence Deltalite II drivers into WinISD. Here's an SPL chart, 1W/1M, with the 2512 in blue or purple and the 2510 in green or yellow (I'm colorblind, hence my uncertainty of the exact colors involved!). Both are with a port tuning of 40 hz:

As you can see, the 2512 has the characteristic midrange hump that shows the volume is quite a bit under the 'ideal' cab volume. The 2510 has a smoother curve, since 42 litres isn't that far under the ideal for the driver parameters (I think ideal was somewhere in the 50's). I'm sort of trying to decide which driver to use. The 12 would be a pretty loud little cab that would cut pretty well. The 10 would be quieter, but smoother, and also has the advantage of not making me do any cutting on the cab to mount it.

Having two ports already there helps. I need to exactly measure the stock ports on the cab tonight and see how close to a 40 hz tuning they get me without needing modification.

If this works well, I might just look for a used Eden CX110 cab and make a matching lightweight extension cab.

This is my first real attempt at messing with something like this. Any thoughts or advice anyone has is very welcome!

Cheers

 

[billfitzmaurice]

Ignore the shape of the curve. Every extra dB you get with the 12 is a free dB. Take them all. Also, SPL is only 1/3 the story. The really important charts are maximum power and maximum SPL, which you should find quite interesting. But I don't get the same result with the 2512, so you might want to check those specs again. And go with 50 Hz tuning, it works much better.

 

[Lia_G]

Thanks very much, Bill!

I didn't see a problem with the TS params, but re-entered them just to be safe.
Here's my driver entry for the 2512 in WinISD:

And here's the new spl plot for the 2512 with a 50 hz tuning:

Thanks again!!!

Cheers

 

[Passinwind]

And here's the new spl plot for the 2512 with a 50 hz tuning:

Hey Liam, you could make those plots bolder and easier for us to see if you feel like it. Go the the "plot" frame and bump up the width to 3 or 4.

Best of luck with the project, BTW.

 

[Lia_G]

Hey, thanks Charlie! I don't see how to do what you're saying, though. If I right-click in the plot window, I don't see an option for width??

Cheers

 

[Passinwind]

Hey, thanks Charlie! I don't see how to do what you're saying, though. If I right-click in the plot window, I don't see an option for width??

Does this clear it up?

Link Removed

best,

---------CE

 

[Lia_G]

Oh, absolutely. Thanks!!!!! I re-did the last plot (DeltaliteII 2512 with 50hz tuning). Thanks!

Cheers

 

[joegeezer]

I also found the Eden combo too heavy for it's size. I just sawed it off carefully, and made a head/cab combination out of it. Now it's the way Eden should have made it. I have 4 of the CX110 cabs, and my head was upgraded to the 405, so I can run 2 ohms at 600 watts with the 4cabs, or whatever I need for cabs. Makes it much easier to handle as a cab-head rig. If you look close, you'll see that the top head part, is just glued on the top of a CX110 cab. Makes it easy to follow the line to saw it off the cab.

 

[Lia_G]

Yep, I saw your thread on that. Very cool idea, and cool job you did with it!

I really like combos, though ... I play a lot of gigs on upright, with 5 minute changeover between artists. I really don't have time to wrangle with a head and cab, plus the upright, on those gigs. A lightweight combo amp is the ticket there, which is what I'm after here. Just using the CXC110 airhead cab because it's laying around gathering dust with a blown speaker!

Again though: what you did with yours is amazingly cool.

Cheers

 

[joegeezer]

That box is about perfect for a DeltaliteII2510. Why don't you save the hassle and just bolt one of those in it? Thats what I plan to do, if I blow any of the stock Eden drivers in mine. I would think that you would keep a better low end and just about as good of SPL sticking with the 2510.
Opening up the hole to fit a 12 in there, is not an easy job. I've done that type of thing several times, but without the right tools, it's not an easy thing to do.
The stock tuning of that box, with the twin ports is at 64hz, by the way.

Do a search for what fdeck did with making and tuning his small box 2512. May be some pointers for you in that thread too. He's a pretty sharp dude too.

 

[Lia_G]

Hey, thanks so much for the info and advice! I appreciate it a ton.

I have a couple of other 1x10 projects lying around, and a 2510 wouldn't go to waste if I decided to go for the 2512 later, so I might just try the 10".

Plus I've been very tempted to try building one of Bill Fitzmaurice's Omni 10.5 cabs, and the 2510 is perfect for that.

Thanks again!

Cheers

 

[billfitzmaurice]

Thanks very much, Bill!

I didn't see a problem with the TS params, but re-entered them just to be safe.
Here's my driver entry for the 2512 in WinISD:

Cheers

You're missing as many parameters as you have entered, so I'm surprised you get a result at all. Is that WisISD Beta? Beta is OK for a quick look see at SPL, but is totally inadequate for design work. It lacks the ability to do max power and max SPL, or to calculate accurate driver sensitivity from the specs-which, BTW, is 94.3 dB for the 2512. WinISD Alpha is the only way to go.

 

[will33]

When I loaded everything in Alpha curves changed and a lot of f3's moved up 4-5hz, alpha is the better program and is capable of a lot more. It is a pain to load a driver in alpha that isn't already in the database as it will reject it if everything isn't perfect to the nth degree. You may have to let it auto-calculate what it wants to and them change the ones you know to be correct after you've loaded the driver in the database. And yes, if you're doing a combo, get every SPL you can and don't worry about the very bottom end. A hump at the first harmonic makes a small combo sound bassy.

 

[fdeck]

With WinISD alpha, I find that it works when I enter the following parameters, and tab across all of the rest of them. When you enter Sd, a bunch of the previous parameters will fill in automatically, as will Qts.

Qes
Qms
Fs
Vas
Re
Sd (which you can estimate if necessary from similar drivers)
Xmax
Pe

I think that Alpha computes input voltage based on the coil resistance rather than the nominal impedance. Since the output voltage of an amplifier is typically computed based on nominal impedance, there will be a discrepancy.

FWIW, my spreadsheet (click on my sig) uses nominal impedance. As of tonight, I just added a MaxPower graph, both sinewave and "waveform based." The latter is based on my hypothesis that system performance can be computed more realistically based on a model of an actual bass waveform. Use with caution, as this technique has never been vetted by the experts. But it gives more optimistic results for how much power a system can handle. The model still neglects power compression.

About the hump in the 2512 graph, you have to decide if a couple dB is really a big deal in the grand scheme of things.

 

[billfitzmaurice]

The biggest difference is calculated SPL. WinISD Alpha and other programs do so based purely on the cone output. They can't/don't consider the dome as an independant radiator, which, usually having a higher fs/lower mms than the cone, typically gives higher SPL within its bandwidth, and will give a higher figure when its sensitivity is averaged into the result.

 

[fdeck]

Quite true. I don't even attempt to model the speaker above 250 Hz. But at that point, it's no longer box-dependent to any significant degree, so I take the higher frequency stuff directly from the driver datasheet. Granted there are probably more precise ways of doing it, but I claim amateur status here.

 

[Lia_G]

Thanks for the further discussion, Bill, Will and Francis.

Bill, yes, I was using Winisd beta. I had originally entered more parameters, but looked at the WinISD help file, which said that not all were required, so I removed some to see if things changed. The SPL figure I used, obviously incorrectly, was the sensitivity figure from the Eminence datasheet. I'll get the alpha program this weekend and do some more homework.

Thanks to all of you for your time in helping an obvious newbie.

Cheers

 

[billfitzmaurice]

Quite true. I don't even attempt to model the speaker above 250 Hz. But at that point, it's no longer box-dependent to any significant degree, so I take the higher frequency stuff directly from the driver datasheet. Granted there are probably more precise ways of doing it, but I claim amateur status here.

That's as good a method as any, since there is no way to predict response above 300Hz or so from specs alone.

The SPL figure I used, obviously incorrectly, was the sensitivity figure from the Eminence datasheet

That's a broadband averaged figure. Part of that average is 85dB at 50 Hz, part is 106dB at 2.45 kHz. WinISD Beta doesn't know the difference, so it will tell you to expect 5dB more than you'll actually get. WinISD Alpha does know the difference, and will give an accurate result.

 

[Lia_G]

Okay, I got WinISD Alpha, and have run some plots comparing the 2510 and 2512 in this box. Again, 2512 is in blue-ish, and 2510 is in green-ish (remember my colorblindness ... sorry if they're not quite right!).

First, SPL, Max SPL and Max Power with the stock tuning of 64 hz:
SPL:

Max SPL:

Max Power:

Next, altering the ports to tune the box to 50 hz:

SPL:

Finally, I decided that if I try out the 2510, I'd likely just bolt it in without messing with the ports, whereas if I were cutting things to mount the 2512, I might go ahead and alter the ports ... so here are plots of the 2512 with a 50 hz tuning versus the 2510 with the stock 64 hz tuning:

SPL:

Max SPL:

To my extremely inexperienced eye, it looks like the 2512 really has a lot of midbass superiority in this box, in the 70 - 150 hz or so range.

In the stock 64hz port tuning, is the big SPL hump of the 2512 something to worry about?

If I compare the 2512 at 50 hz versus the 2510 at 64 hz, the SPL chart is very similar, and the midbass difference on the Max SPL chart is smaller (but still there). However, there's now a large low bass advantage for the 2512. Hmmm.

I'm tempted to just try the 2510 with the stock tuning and see how I like it, as JoeGeezer suggested above. Then again, that large midbass advantage for the 2512 makes me very curious about it as well. Still no firm decision, I guess.

Thanks again for everyone's input, and for guiding me toward WinISD Alpha ... much better program, and I'm glad to have the extra data that it provides. FDeck, I'll also be trying out your spreadsheet.

Cheers

 

[greenboy]

Something looks wrong there on the max power / cone excursion front. If I recall, max power for both a single 2510 and a single 2512 falls in at about the same place in typical bass cab alignments.