It’s the SB Acoustic Rosso 65CDN-T.
Hmmm, I don’t know GM, why wouldn’t altering the rear chamber change Fr? Seems like Troy knows what he’s doing and it makes sense to me so I went with it.
Hmmm, I don’t know GM, why wouldn’t altering the rear chamber change Fr? Seems like Troy knows what he’s doing and it makes sense to me so I went with it.
Didn't say/imply anything re Troy, only never seen a true CD (Altec, JBL, EV, etc.) that could be tuned lower this way, though have designed/built quite a few mid, woofer CDs using cone/dome drivers where final tuning was done via its compression chamber and this one's response indicates the same kind of (DIY) design response, so yeah, could tune it quite low with its (much reduced) peak power handling being the limiting factor.
When I saw that Troy had used this CD with the expanded rear cover on the speakers he recently made for Don Sachs, and read what Mr Sachs said about the sound, I figured that was enough of an endorsement to give it a try. It give me the opportunity to see if crossing at 500Hz, even 600, will sound good and keep the Faital in its comfort zone and have more of the mids being handled by the same driver. We'll see, I can always put the original cover back, and I can also play with the crossover point. I have two xover modules coming with the K231, 500Hz and 600. I'll listen and measure. If the 600 is better, I'll order a 700 and compare the two, etc.
This stuff really is not for the impatient, I've learned.
This stuff really is not for the impatient, I've learned.
Hi @ Bryan S.
what crossover point did you settled at? And sort of rear cover modification was done on CD?
I see him offering few 3d files for rear chamber!
what crossover point did you settled at? And sort of rear cover modification was done on CD?
I see him offering few 3d files for rear chamber!
I kept it at 600Hz. Measures really well there and the two drivers blend seamlessly to my ears. Recently swapped in an 800Hz card to the Sublime and the Faital just doesn’t carry that low mid as well as the Rosso/horn combo. I’m really impressed this CD plays so cleanly and full sounding down to 600, it’s beautiful there. It wouldn’t be possible without Troy’s rear covers to exploit what this driver can do. I don’t have the link but as far as I know there’s only one file for the 65CDN-T rear cover. Troy printed them for me as I don’t have a 3d printer.
As far as alignments are concern any minimal phase shift is what I would go too, my old B&W 801's had a 6th order alignment using a flat quasi Butterworth. The extra 12 db filter is applied in the preamp section, where it allows a sharper cut off at Fs, reducing cone movement below Fs, such that you can increase power with out getting distortion (clipping) and add about a half an octave to the response curve. Many bi-amp systems or powered subs do this. On the B&W 801's, the speaker/cabinet alignments were the same as the vented (same enclosure size) such that they didn't need to retool the cabinets, just added the tuned vent and active filter - it became the 801 matrix series. As far as cross overs, it depends if the coaxial tweeters are aligned physically to the woofers voice coil. If it isn't then you would need to use a digital crossover with separate delays . They are now quite a few dsp related crossovers that are quite reasonable in costs that would work well, and being software driven can be easily tweaked
If possible avoid coaxials that have the horn as part of the woofer. They don't sound nearly as well as separated coaxials. Something to do with both the Doppler issues as well as timing delays.
If possible avoid coaxials that have the horn as part of the woofer. They don't sound nearly as well as separated coaxials. Something to do with both the Doppler issues as well as timing delays.
