AARGH! Need help for Dynaudio Aries Diy Project modification

[francorovereto]

Hi all,
I need a little help from the diy-gurus http://www.diyaudio.com/forums/images/icons/icon12.gif here in this forums...

I'm beginning to build a Dynaudio diy project I found on the web. The Aries. I've heard them and I really love the way they sings.
This is the link to project:

http://www.gattiweb.com/images/dynaudio/aries_2.pdf
http://www.gattiweb.com/images/dynaudio/aries_3.pdf
http://www.gattiweb.com/images/dynaudio/aries_4.pdf

Sadly The original drivers is no more avaiable and I can't find the woofer used. I've found a pair of esotec d260 tweeter and two variovent, fortunately.
I have a pair of Dynaudio esotec mw172 (car) woofer ( http://www.gattiweb.com/images/dynaudio/MW172.pdf ) I bought for a few bucks, and wish use these driver in replacement to the original esotec 20W75 ( http://www.gattiweb.com/images/dynau...sotec_data.pdf ).

T/S parameters are a bit different, but the drivers shares the same cone and a lot of particulars. Maybe with a few modifications for the box volumes (an aperiodic double-chamber design) and for the xover (i'm not sure) it may work in a similar manner. I'll say you...
Unfortunatly I don't have powerful software to make fine calculations and the skills to use these appropriately, and the info about variovents and aperiodic vents are very empyrical... only a few indication on northcreek's site. ( North Creek Music's new MAPD driver loading )
So, if you can give me some good advices it would be immensely appreciated.

Principally my doubts are:

1)Box internal volume for first and second chamber: the Qts,qms, etc and vas of the woofers are different. Maybe I could mantain the proportions following the Vas differences..but I'm not sure cause the different divers qts's could drive to different qtc anyway. And i would mantain the original qtc value or approx. it.
I can't understand the principles of construction of ARIES project in relation with the original 20W75 woofer parameters.
(nb:Winisd calculations give me the best responses with mw172 at 28-32 litres in a sealed, poorly stuffed box.)

2) Could the crossover work fine with my drivers? Same tweeter, but the woofer has different parameters. Fortunately, is a first order Xover and only an inductance should vary.

For zobel network, could I simply replace with the values that Dynaudio give in the datasheet of MW172?

Maybe i'll change R1 too, but tweeter level is one of the last tweek i will do.

Thanks a lot for your help.

An appassionate newbie.

ciao

[PeteMcK]

The original box appears to nothing more than a heavily stuffed closed cabinet.
From Unibox sims, your replacement driver will have a slightly higher F3 in the same cab - 63Hz vs 58. If you vent, for a more shallow LF roll off, you will get an F3 of ~ 48Hz.
I think this driver would do well in a slightly larger box, say ~ 70L tuned to 30Hz.
The 2 drivers appear to have a similar impedance around 2 Khz, so even though I'm not sure of the xover freq, you may be able to use the original xover...

[francorovereto]

thank for your answer!

I don't want to go with vent cause I have tried the woofer in a couple old (cr**py) cabinet, vented and sealed, and the vented one sound a bit muddy, slow and boomy. To much bass. The sealed one sound tight clear and nervous, and I like it even with a higher F3.

More than a heavy stuffed enclosure, it should be a two-chamber aperiodic enclosure. Sealed but with two chamber that communicate trough a flow resistor.
I think that the variovent will vary the q of the driver in the midrange (little chamber work) vs low range (little+bigger ch. work). I don't find very much on the web.

I hope the crossover will work. Teorically the freq of the xover should not shift very much, but without precision measuring tools it's difficult to say..

[PeteMcK]

re:'I have tried the woofer in a couple old (cr**py) cabinet' - what size cab did you use?
if it was too small that may account for the boomy result; Your woofers seems to be OK in about the same size cab for both sealed & vented, so you could vent, & if you don't like it, seal off the vent... (a vent at 30Hz is well out of the way of most musical info too, I'm sure a lot of the problems people have with vented cabs is that the vent freq is too high...)

[francorovereto]

One was 25 lt, one 44 lt. I tried both vented (with dummy tubes external to box) and closed (sealing the vent + adding damping stuff) and ever prefer the sealed bass. More punchy. Far more controlled and clean. Reflex bass is MORE but not so clear and fast.
With a qts of 0.51 seems to my that this driver is suited for both loading but don't will do a marvellous work in reflex load. Just work. I' m sot sure anyway.
I'd like to try aperiodic loading instead. One plus benefit would be the size of the box.
Since waf is really an issue, i'd prefer a little box.. 70 litres are a bit on the big side!
Thanks for your answer!

[francorovereto]

ps: i'll try with a 30 hz vent anyway. The old vent was 41-42 hz I think (approx. in winisd box calculator)

[francorovereto]

I'd like to have others opinions about this project. A good beginning anyway!

[francorovereto]

Still have a doubt: qts=0.51, reflex loading @ 30hz 60l ..... maybe it will be a quantitative bass, but not tight and controlled. Isn't?

[francorovereto]

I tried.
Still prefer sealed sound. The duobt remains the same: how to vary inner dimension of the original project? On North Creek music site they consider right this ratio:
1 chamber: Vas/3
2 chamber: Vas
(using S.S. flow resistor, not variovent)
Any advice?