Choice of BD15 for our High-end Hifi project? (BD-Design)

by Jose Hidalgo , Sunday, April 15, 2007, 17:38 (6230 days ago)
edited by unknown, Sunday, April 15, 2007, 18:24

Hello everybody, greetings from France. Please allow me to introcuce myself.

I'm a part of a small team of friends working on a High-end, Home-Hifi, 3/4-way active, DIY speaker project (max SPL about 105dB, source a fine-tuned PC Audio with a Lynx TWO-B card, everything software-EQ'ed with IZotope Ozone, and some of the best lateral-MOSFET DIY amps you can dream of).

We are aiming to find some of the best modern drivers the technology has to offer today, regardless of their cost (well, *almost* regardless of course ! unfortunately we have a budget ). For example, for the mid we will probably work with the Thiel-Accuton C90-T6, which seems to be just one of the best modern mids out there. Now we are aiming to find a bass or mid-bass driver that will go up to 200-250 Hz and catch up very nicely with the Accuton.

We are very cartesian people, so we mainly believe in the technical specs (physics are physics, no miracles), in the optimization process (specs are nothing without a good measuring/optimization phase) and in the final results.

For this, our choices are as follows :
- 12" or 15" : not more than 15" because most 18" drivers will have trouble going up to 200-250 Hz. And not less because subjectively we do not want less than 12".
- Electromechanical specs close to Accuton's ones in order to facilitate a seamless active crossover (this includes a rigid membrane, a high BL but also a quite low Mms, a low Rms, a underhung motor, etc.).

We have searched... a lot. And when I say a lot, I mean... a LOT. We have looked at a bunch of driver manufacturers from all countries. Most of their drivers just don't fit our specifications (BL too low, Mms too high or not rigid enough, Fs too low, Vas too low...). And the very few of them that could eventually fit are either too expensive (Fertin 30EX...) or almost impossible to find (JBL 2220J, 2220B, 1500AL...).

And our search has leaded us... here, to the BD15. Now can the BD15 be THE driver we have long dreamed of ? Maybe... we hope so ! Its T/S parameters are very good indeed. But of course that's just the beginning.

So to begin with, we'd like to have your comments (positive I hope ) on the relevance of the BD15 choice for a High-end Hifi application up to 200-250 Hz, crossing over with an Accuton C90-T6.

After that, we'd like your advice on the best enclosure type for the BD15. For example, most peope today just go bass-reflex without even knowing why. Big sealed enclosures (Qtc = 0,50) have also their advantages (group delay / better impulse response). We do not have a preference here, so we really would like to hear your best BD15 enclosure advices for our application. BR or sealed ? Damped or not damped ? How ? Where ? When ? Etc.

Of course, although we're some very passionate (and crazy) guys, we're not professionals and we can make mistakes. But hey, that's just part of the fun of it don't you think ? :wink:

Thanks in advance and best regards,

Jose

P.S.1 : I have read that the early BD15's needed some coating with glue. I assume all the new BD15's are ready to use and don't need any additional work ?
P.S.2 : Is there a way to lower the BD15's impedance ? WinIsd says it's 20 Ohms, which is very high !! (of course we could put 2 BD15's in //, but that would also double the price ). Wouldn't it possible to have a version of the BD15 with a lower impedance ?

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