Could someone model these drivers for me?

[DJNUBZ]

I already have built this speaker using the plans on the site and they sound great. The problem is there is no bass at all. The t/s was not orig on the site because the designer wanted an outside company from the driver builders to test them. The web site is

http://www.parkeraudio.net/prod03.htm

If you also have the time could you model these driver for the enclosure designs on the site already and see if it is a good match?

[planet10]

Given the numbers on that web page. my modeler comes up with something quite strange.

dave

[DJNUBZ]

could you tell me what each line color means?

[planet10]

black is the frequency response, blue is the impedance, and magenta the group delay...

looking at the graph i'd guess that the bottom on these speakers has some problems, this is the kind of alignment i'd just toss out as unsuitable -- are there any tricks he is doing that would invalidate the sim?

dave

[DJNUBZ]

I don't think he was givin correct t/s when he had the drivers made. He recently had them tested by a third party and these are the specs he got back. They have a great midrange but the speakers have little to no bass and sound pretty thin. I am sure there is a more suitable enclosure then the one he designed but I don't have the s/w to design one. Personaly I was thinking about a TL or a back loaded horn but I don't have the tools to see if they would work.

[planet10]

The Q is low enuff that a back-loaded horn might work... tricky to design thou.

The Vas given is very low for a 6.5" driver, i'd really question that number

dave

[DJNUBZ]

these speakers are pretty stiff.

[Nappylady]

I'm not sure that modelling is incorrect; the huge hump in output at ~64hz could be intentional. That way, when you play the live version of "Hotel California," the listener hears that big *THUMP* and feels it in his chest, and says, "wow that's a lot of bass! These speakers are very good!"

What he doesn't realize is that it may be a lot of bass, but it's not actually very good bass.

[johninCR]

Dave,

I think you converted the .78 Vas to cuft as if it started as liters, but I'm pretty sure it must be cuft. I tried Martin's TQWP worksheet and got what seem to be pretty good results. I do have a question about the inputs. Since this is 2 drivers, is the Vas doubled or cut in half ? I only got good results doubling Vas, so I hope it is correct. The only input changes I made were for Re, Sd, and Vas to account for there being 2 drivers. Do any other T/S parameters change with dual drivers? I came up with a 60" pipe, 56cm top (25% of Sd), 904cm bottom (4xSd), drivers centered at 50% and a 4"dia 8" port. I was trying to get a pipe that looked pretty good with the Parkers and an FE206E, so I can use a changeable baffle.

Also, I couldn't find any examples of folding a TQWP with an MTM set of drivers. I'm guessing that the tweeter will need to go on top, but I'm unsure of that effect since this is a crossoverless MTM design. Can it be folded and achieve the same result as a straight pipe using 2 drivers? It would be nice to avoid a 60" tall speaker.

I bought these things to get high efficiency and low impedance for my Decware amp, but the recommended BR models silly with no bass below 90hz or so. Any suggestions for alignment would be greatly appreciated. Right now I'm leaning toward a TQWP due to the simplicity in build, GM mentioned that 2 drivers is beneficial, and a number of people like their 206's in a pipe, so with the higher Qts and slightly higher Sd, I think these will be even better.

[GM]

Greets!

Right, Vas, Sd doubles, Re, Le halves for parallel wired. BL changes only a tiny fraction so can be ignored. T/S max flat assuming Vas is in ft^3 and ~no series R: ~10.366L, ~111Hz F3, ~92Hz Fb.

I didn't see any dims for the cab other than a too large ~35L net Vb/61Hz Fb, so can't comment on the FR beyond that if driven with an SS amp they are only capable of 'one note' bass centered around ~61Hz.

I assume though that the Zen has significant output impedance so the effective Qts will rise, 'filling' the cab up to some extent, but may not be enough so some series R may still be required to flatten it enough if the XO and cab width doesn't account for any/enough BSC. At a glance it looks like Qts = 0.376 is required.

Anyway, once dialed in, my SWAG is that based on the limited driver specs then a much more 'solid' 40Hz alignment than this one can be had from this kit, though the XO may need to be tweaked.

GM