How small can you go with the 2512-II ?

4Mal · #1 02-21-2011, 02:20 PM

Looking to do a winebar cab using an extended xmax 2512, combined with. Faital 6.5 mid. This is acoustic support work so the db requirement is pretty low. My 300 watts of GK micro should be more than enough.

I'm hoping to trade efficiency for small size and reasonably deep response for a 4 string bass under archtop jazz guitar, mandolin, dreadnaught... That sort of thing.

So how small can I go and what would the porting look like?

My carpentry skills generally outweigh my winisd skills ...

This will eventually have a passive cross but will start off as a biamp cab until I figure out what point to cross at - then I'll come on back begging for crossover advice

fdeck · #2 02-21-2011, 06:03 PM

I've got a brief article on a small box with the 2512-ii driver in it, at my web page.

4Mal · #3 02-21-2011, 07:16 PM

Sweet - I downloaded it for a little couch time absorption.

dug dog · #4 02-21-2011, 09:12 PM

A very informative read, indeed. I read it many months ago, but still got a great deal out of reading it again tonight.

4Mal · #5 02-22-2011, 11:49 AM

le Bump
in the hopes that maybe Duke will chime in ...

dug dog · #6 02-22-2011, 12:58 PM

In the meantime, a pretty picture for your viewing pleasure.

That's the 2512 II in 3 different sized boxes all tuned to approximately 47 Hz. The yellow is 1 cubic foot, pink is 1.5 and green is 2.

I think you'd probably rule out the 1 cubic footer, due to the mid bass bump of over 2.5 dB and the F3 at around 83 Hz. However, maybe some creative EQ could make it viable.

Both the 1.5 and 2 cubic foot options look reasonable to me and depending on how hard you're gonna rock the wine bah, you could probably get by with a single round vent somewhere between 4 and 8 inches long with a 4 inch diameter.

Passinwind · #7 02-22-2011, 01:33 PM

Mal is pile-drivingly heavy, don't let him fool you.

dug dog · #8 02-22-2011, 01:35 PM

Every time I see that pic of Schultz, I have to laugh...

billfitzmaurice · #9 02-22-2011, 02:01 PM

Quote:

Originally Posted by dug dog

In the meantime, a pretty picture for your viewing pleasure.

Informative as those charts are what really matters is maximum SPL.
You'll get a lot better result from the smaller boxes with lower tuning.
If you want a really small box there's no substitute for the 3012HO.
I get very different results, making me think there are some errors in your driver database. Or is that WinISD Beta? If so that's the problem, as it's not very accurate.

dug dog · #10 02-22-2011, 02:16 PM

I'm using the Alpha version of Winisd. The 2512 data that was in the original database doesn't match what's shown on the Eminence site. I'm wondering if the "II" in the driver name suggests that there was a revision to the original driver. The file I used is one that I scooped from Greenboy's site some time ago and it matches the Eminence site.

billfitzmaurice · #11 02-22-2011, 02:30 PM

Quote:

Originally Posted by dug dog

I'm using the Alpha version of Winisd. The 2512 data that was in the original database doesn't match what's shown on the Eminence site. I'm wondering if the "II" in the driver name suggests that there was a revision to the original driver. The file I used is one that I scooped from Greenboy's site some time ago and it matches the Eminence site.

Whatever you've got there is incorrect. The DLII 2512 in 1 cu ft with 47Hz Fb only has a 2dB hump, while f3 is at 82 Hz.
Your chart scale makes things look more severe than they are. Lose above 300Hz, as accurate modeling results don't go higher than that, and expand your vertical scale; plus 12dB to minus 30dB works well.

dug dog · #12 02-22-2011, 02:52 PM

I see what you mean about the chart scales making things look worse than they are. I set the vertical scale that way hoping the numbers would be bigger and easier to read for old guys like me.

I'm not sure what's up with our graphs not matching. I just re-entered the data from the Eminence website and Winisd spit out the same thing.

Oh well....

2512 Data Sheet

4Mal · #13 02-22-2011, 03:16 PM

Quote:

Originally Posted by Passinwind

Mal is pile-drivingly heavy, don't let him fool you.

oh yeah, for an acoustic support guy I surely am ...

4Mal · #14 02-22-2011, 03:19 PM

Quote:

Originally Posted by billfitzmaurice

Whatever you've got there is incorrect. The DLII 2512 in 1 cu ft with 47Hz Fb only has a 2dB hump, while f3 is at 82 Hz.
Your chart scale makes things look more severe than they are. Lose above 300Hz, as accurate modeling results don't go higher than that, and expand your vertical scale; plus 12dB to minus 30dB works well.

So Bill, what is your take on what is essentially a low volume, small stage mon based on the DL 2512II and a 6.5 mid ? a direct radiating box as opposed to horn sorta thing.

I'm already covered on the (for me) high output rig. So this is about getting to something better than my Mojo Sonic 1x10 ...

billfitzmaurice · #15 02-22-2011, 08:21 PM

Quote:

Originally Posted by 4Mal

So Bill, what is your take on what is essentially a low volume, small stage mon

Use a 2510

DukeLeJeune · #16 02-22-2011, 10:09 PM

Quote:

Originally Posted by 4Mal

le Bump
in the hopes that maybe Duke will chime in ...

Well, I think Fdeck's design pushes the lower limits of box size for the 2512, and he went into it with eyes wide open and made very intelligent tradeoff choices. I'm gonna talk my way around in a circle and end up pretty much right back in Fdeck's camp.

I like to minimize the loudness discrepancy between the first overtones of low-B and low-E (B-0 and E-1). The 2512 isn't the ideal 12 for doing this in a small box, but it's not too bad either. In 1.3 cubic feet tuned to 37 Hz, we're "flat" at 82 Hz and -4 dB at 62 Hz.

Overkill perhaps, but just for fun let's look at the 3012LF in a 1.3 cubic foot box tuned to 49 Hz. Now we're "flat" at 82 Hz and -2.5 dB at 62 Hz, which is quite good. And, a 6" midrange will probably reach down low enough for the 3012LF. Hmmm.... there's something fearfully familiar about this basic configuration...

Now here comes another fly to land in your ointment. You described your 2512 as having an "extended xmax" (cough-cough-Avatar??-cough). Chances are it has slightly different parameters from the stock 2512, and I would expect those different parameters to push things in the wrong direction, as least as far as implementing my low-end-target philosophy in a small box, but you can probably get there by going with a little bit bigger box, like maybe 1.4 cubic feet.

So to sum up in generalities, my suggestion for using the 2512 in a small box is to go with a lower tuning frequency than your normally might. This is what Fdeck did, so I'm hardly breaking new ground here, but I think that's part of the success of his design.

4Mal · #17 02-28-2011, 05:52 PM

Yep. Avatar indeed. Food for thought. Thanks all, well most anyway :-)

Arjank · #18 03-01-2011, 01:10 AM

Quote:

Informative as those charts are what really matters is maximum SPL.
You'll get a lot better result from the smaller boxes with lower tuning.

Use e.g. Boxsim instead of Winisd, that program also shows you the maximum spl you can get from a specific driver in a specific enclosure.

Bill, why do you think that you get higher spl from a smaller box with lower tuning? Maybe I just don't understand you right

The woofers xmax, distortion figures and rms power determine it's max spl in the lower bass. You will need to put more power in it when a woofer is placed in a smaller cab (read: to small) cab tuned to the same frequency as in a bigger cab. So it's sensitivity is lower which means lower spl for the same given power.
When I see the q of this driver(2512 II) the ideal cab would be approx the same as it's Vas which is in this case 5.2 cu ft (147liters!). But you'll be rewarded with a -3dB point of approx 37hz. But, the OP has a 4-string so such a low -3dB point is not necessary. I would put the 2512 in at least 2 cu ft and tune it to approx 45hz or a tad lower else you'll get to much midbass. But, if you like that, why not.....