DIY software

**Exocer** · **04-26-06, 11:33 PM**

Hey guys. I would like to ask everyone which is their favorite program to model their drivers in? Right now, my favorite program is Unibox (actually, a cool excel file). It seems hella accurate and is more than helpful, with a very simple user interface. Currently Unibox is aiding in the designing of my 2nd enclosure for a Rythmik Audio DirectServo kit. This one will be a vented enclosure tuned to 20hz. Check out the graph thus far

**Exocer** · **04-26-06, 11:54 PM**

I accidentily deleted the rest of that post...at it was Long too

Ah well, Just wanted to mention if anyone needs help using unibox I am here to try and help. It'll take a little while to understand the graphs, and to understand how to convert from the metric system to ours and vice versa. But with help from google's conversion feature you will be suprised how fast you can design speakers

**Sonnie** · **04-27-06, 12:00 AM**

Gee, I'm glad you understand all those lines... they make me drunk.

**JCD** · **04-27-06, 12:06 PM**

If I remember correctly, Unibox is for designing subs?

One quick question (note -- I'm a rank amateur at speaker design)
How can you come up with a SPL for leaks? Wouldn't you assume leaks=0?

Also, what other programs have you tried? The only one I've really played with was WinISD.

JCD

**Exocer** · **04-27-06, 04:51 PM**

Sonie, LOL.
Jcd,I haven't tried any other programs.Well I did open winisd and it confused the poo out of me. Probably chose a bad time to try and understand the user interface. But I definitely know Unibox can be used to design more than just subs. I've actually modeled up an MTM speaker with two dayton da 175 7" drivers (Some dude was generous enough to send me two for free) and things looks pretty good with a 3" port.

There are three choices of leak options in unibox to simulate output in situations where there will be: no leaks, minimal, or minor leaks. The program derives the output for leaks automatically based on variables I don't even know and which option of the three i mentioned previously you've chosen. It is nothing more than theoretical data that accounts for little or barely any change in the overall frequency response in most cases.

Jcd, you're a rank amateur at speaker design...maybe you can give me a few tips?

**bobgpsr** · **04-27-06, 06:34 PM**

I started out last Feb with UniBox and modeled this:

But I added a lot more bracing thereby cutting down the internal volume. Still got a good listening position plot (using a LinearX M31 cal mike with TrueRTA software) of the result:

The top trace was the result of smoothing to 1/6 octave and shifted up 10 dB.

The Tumult sub was tuned (as measured with close mike) to 15 Hz:

This is my downstairs basement system and I do not have a BFD there. Thankfully it is fairly flat, but I want to get the new BFD that Sonnie is pushing for to use with this. Then I will use REW and MIDI like I did upstairs with the PC-Ultra and old BFD.

Bob

**Exocer** · **04-27-06, 06:51 PM**

That tumult is a monster. Puts my Rythmik driver to shame. How big is your listening space bob?

**Sonnie** · **04-27-06, 07:07 PM**

I just thought I was drunk... I think it's past that.

I might (read "might") learn a little something from you guys.

I've heard of people using that Tumult in there cars before... totally awesome sub.

**bobgpsr** · **04-27-06, 08:12 PM**

Quote:

Exocer wrote:

How big is your listening space bob?

Around 7000 ft^3 now. It is a full basement room. I knew I needed something extreme to try to fill it with decent SPL. That is why I went with the 15" Tumult plus two 18" PRs. I drive it with a Mackie M1400 pro amp that gives 1400 watts bridged into 4 ohms. Got up to 110 dB SPL using a 30 Hz sine before the circuit feeding the Mackie popped.

The nice thing about the Tumult is its very low distortion of 2% @ 13Hz 102 dB SPL as measured with this:

Just a bit of a SWAG looking at the second and third harmonics and the table in the TrueRTA help file.

Bob

**Exocer** · **05-01-06, 07:08 PM**

Awesome job bob! For me to move that much air, I would need about 2.5 Rythmik servo kits ****. Somewhere down the line when my listening space is larger than 10'x13' i'll upgrade to a second Rythmik kit. I haven't really decided if ported is my cup of tea yet...may go with PR's like you. How is transient response effected by a PR allignment? Would you say it is an improvement over ported but not quite as good as a sealed allignment?

**bobgpsr** · **05-01-06, 08:25 PM**

Actually transient and group delay response is supposed to be worst for PRs over normal ported. But once you tune well below 20 Hz, say 15 Hz, I can't see how it matters for music. You don't hear it anymore, just FEEL its effects.

The big advantage to my mind, of PRs is the very low tune with absolutely no port resonances, no port noise or port distortion. Of course you have to stay well within the linear Xmax of the PRs to keep distortion down.

Bob

**Exocer** · **05-01-06, 08:35 PM**

Got it! So PR's must be for all out HT buffs looking for nothing but the best extension without all the downsides of ports. Sounds like your project is comming along smoothly, or is it already complete??

**bobgpsr** · **05-01-06, 09:11 PM**

Quote:

Exocer wrote:

...or is it already complete??

Well

it is glued and working. But not outside finished (kind of a Jack Gilvey look

).
Been enjoying it anyway since it is in an unfinished basement since I verified its mechanical and electrical performance. Thinking about testing it outside with Ground Plane (GP) measurements. Need to line up a laptop (from my son) and adequate electrical power for the pro amp (I think I need a 20 amp service and extension cords).

Future plans are to pull the PRs and driver to sink the bolts properly through the outer part of the included rubber gaskets. Doing a proper lining of the enclosure interior wall with dampening fiber (may not be able to tell if that really helps), doubling up the 12 gauge wire inside. Doing a roundover on the Baltic Birch corners with the router. Sanding, staining and sealing. Lots of little things to do. Fortunately no rush.

Bob

**Exocer** · **05-01-06, 09:17 PM**

No rush here either! my first enclosure is far from done. Last I've done is glue everything up and go over the edges with a flush trim bit. I still have to paint it and am thinking about gluing some interior re-inforcement for the rear part of the enclosure. The rear seems to fail the knuckle rap test while the front doesn't. It's only 1 measly layer of MDF, while my front is 2.25" thick..I may glue some small MDF slices to connect the rear wall with the closest circle brace in a few places. Hopefully that helps...

**Danny** · **05-04-06, 04:51 AM**

http://www.diysubwoofers.org/prt/ Is an excel spreadsheet with many features if anyone finds it helpful. Give me a yell if you need help with it

**Exocer** · **05-04-06, 07:33 AM**

Danny, cool. I'll check it out.
When/if you get and chance swing on over to the member introduction, let us know a little bit more about you

Welcome aboard!

**Exocer** · **05-06-06, 12:25 PM**

bob, my enclosure edges are sorta "rounded" because of sanding. Would it be possible to still apply veneer or is painting my only route now?

**bobgpsr** · **05-06-06, 12:39 PM**

Quote:

Exocer wrote:

bob, my enclosure edges are sorta "rounded" because of sanding. Would it be possible to still apply veneer or is painting my only route now?

Hmmm...stiff veneer? Might be a problem IMO but I am not experienced with this. Might best be asked over at HTGuide in the DIY section. steve nn seems to be the expert.

Bob

**Exocer** · **05-07-06, 08:51 PM**

Yeah it'd definitely be a problem. Looks like i'll be buying a can of spray paint...or maybe go with some good Truck Bed Liner. At this point I may nix the vented enclosure Idea. I am enjoying the sub again as is (sealed). Maybe a project for the living room (where no critical listening occures) would be a good place for a vented sub, it'll need the increased output.

ANyway, I am still a bit unclear about how the amount of air a given driver can push @ a given input power will effect the FR of the design. Does a higher Sd x (2(xmax)) value always equate to higher SPL when compared to a driver with similar efficiency fed with the same amount of power?

**Brian Bunge** · **05-07-06, 09:23 PM**

Man, if Steve's an expert at veneering then what does that make me?

I've been veneering for about 5 years or so and have gotten excellent results veneering around rounded corners. You could technically still veneer the cabinet if you actually rounded over the edges with a router and at least a 1/2" roundover bit. That's assuming you only round over the edges running one direction (either all the vertical edges or all the horizontal edges, but not both). Otherwise, you are probably better off just painting the enclosure.

Concerning your question about Vd, if drivers have similar sensitivities but one displaces more air, then it is capable of producing higher SPL's.

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