DVC series vs. parallel wiring?

[Brian Bunge]

Hey guys, I've been trying to model the Fi Audio Q18 driver (d2 version) and for some reason I'm getting huge boxes. I have to go 10x Vas just to get a Qtc down in the mid .6 range.

So I remembered that you have to adjust some of the parameters based on whether you're wiring the vc's in series or parallel. But of course I can't remember how to do that. I'm assuming since the Re specs are given as "per coil" that the other specs are as well. I know how to adjust Re based on whether the coils are in series or parallel, just not the rest of them.

Any help you guys could give me would be greatly appreciated!

Brian

[mmoeller]

Not an expert here, but it would seem to me that the Qts of that driver is already .57. Any box will raise that value. I'm not suprized that the Qtc is around .6 even for a 10x Vas setup. I can't remember the factor of increasing Qts at a 10x Vas, but it is still a mutliple just over 1. 1 being no effect from the box (Qts=Qtc). So in a perfect world .57 Qtc would be the best you could hope for. I believe that Thomas-W had mentioned before that Fi Audio was able to make a version with a lower Qts for IB applications requiring a Qtc of closer to .5.

Then again I might not have awnsered the right question. I know you can edit the driver parameters in WinISD to portait series or parallel voice coils, but I have issues with that sometimes too.

[Brian Bunge]

I thought about that too. The Qtc is a bit high compared to many drivers. I'm just scratching me head as to how these would work in the relatively small enclosures of car audio. Of course, I'm used to seeing high Q sealed enclosures for that environment, but we'd be talking about a Q above 1 for anything that'd fit in a car.

I guess my best bet would be to email them and see what's what with the specs.

EDIT: Oh, and actually like the driver as is for IB apps. But then again I'm not really wanting a Q down in the .5 range.

[Scott Simonian]

Brian, there was a thread about the custom Fi Audio Q18 at AVS...

Ah crap. I forgot what the thread was...brb.

[collo]

Here's the conversions between series and parallel coils

[ThomasW]

Scott,

Scott at Fi will custom configure drivers to order. He's done that already for a couple IB sub builders.

[Dennis H]

Hi Collo,

You might want to add a couple of items to your table.

Single - Series - Parallel
Le - 2*Le - Le/2
Bl - 2*Bl - Bl

Of course the problem Brian is having is he doesn't know how the driver is wired for the published specs. Sometimes they even mix and match to make individual specs look favorable.

[jonathanb3478]

Of course the problem Brian is having is he doesn't know how the driver is wired for the published specs. Sometimes they even mix and match to make individual specs look favorable.

I believe it is, as I had problems where the published QES and such were way off when calculated using the Bl they provide. Using the Bl verification process WinISD's help file suggests to help determine series or parallel wiring in DVC (or more than just DVC) by reverse calculating the Bl, the calculated Bl was lower than the spec by ~33% on every driver I entered in multiple driver lines. :M

I gave up. I like the TC-2000 well enough for EBS (my preferred allignment) that I just don't want to invest any more time trying to figure out what is up with the published specs of those Fi drivers.

[cobbpa]

I'm not sure of the formula...could someone tell me the $/liter number for the Q18? Just kinda curious and would like to compare it vs. the list on Ifinitely Baffled.

Xmax: 27mm
Sd: 1210cm^2
Price :$309

I don't know what else is needed? Thanks for whoever plugs this in!

[ThomasW]

Vd= 6.534L

the formula is Sd times Xmax doubled

[cobbpa]

Thanks Thomas! Makes it interesting to compare on that chart...made me realize its displacement / efficiency / value are very similar to the Avalanche 18 in many ways. Different Fs. Hmm. Just interesting..don't wanna turn this into a comparo thread..but thanks for that quick response & calculation!

[collo]

You might want to add a couple of items to your table.

Single - Series - Parallel
Le - 2*Le - Le/2
Bl - 2*Bl - Bl

Thanks for the tip Dennis. - it's done! :T

[cobbpa]

Hey Brian...don't forget to let us know what's up when you hear about the specs :P

[cobbpa]

Ever find out much on this Brian??

[Brian Bunge]

I never got around to emailing them to ask. I'll do that sometime today if my work load isn't too big.

[cobbpa]

In case anyone is still thinking about 18" drivers, as I am ..I'm not certain because I can't remember what the page looked like before...but it looks like the numbers have been cleaned up a bit. Multiple figures are given for each spec and most of them are different. I kinda get some funny graphs when I model it though.