A request for critics before starting to cut mdf...
Here's the TL I came with for the Vifa P17WJ. I used MJK's worksheets and the specs for the Vifa P17WJ given by Zaph ( http://www.diyaudio.com/forums/showthread.php?s=&threadid=28673 ).
- The best simulations results were for a tapered TL with a ratio of 6:1, tuned at 40Hz. The length of the pipe is at 137cm and the driver is offset at 1/5 of the pipe. (see attached picture. At the bottom of the pic, the results for a "classical TL").
- The pipe is folded once and the port is at the back (inspiration comes from the FTA2000 of Bob Brines). Outside dimensions are : 930mm (H)- 244mm (W) - 384mm (D). 22mm mdf used.
- I still have to play with the location of the tweeter.
Here's the TL I came with for the Vifa P17WJ. I used MJK's worksheets and the specs for the Vifa P17WJ given by Zaph ( http://www.diyaudio.com/forums/showthread.php?s=&threadid=28673 ).
- The best simulations results were for a tapered TL with a ratio of 6:1, tuned at 40Hz. The length of the pipe is at 137cm and the driver is offset at 1/5 of the pipe. (see attached picture. At the bottom of the pic, the results for a "classical TL").
- The pipe is folded once and the port is at the back (inspiration comes from the FTA2000 of Bob Brines). Outside dimensions are : 930mm (H)- 244mm (W) - 384mm (D). 22mm mdf used.
- I still have to play with the location of the tweeter.
Attachments
Ben,
The design looks good, I like tapered TL enclosures. The only concern I have would be how you plan to handle the baffle step issue. The second set of calculations in the worksheets should help determine how the frequency response will look. Have you run those calculations and can you post the SPL response?
The design looks good, I like tapered TL enclosures. The only concern I have would be how you plan to handle the baffle step issue. The second set of calculations in the worksheets should help determine how the frequency response will look. Have you run those calculations and can you post the SPL response?
To be fully honnest, I intended to use a serie crossover developped for the same drivers but for a double BR enclosure, with the same baffle width. The BR enclosure is just slightly less deep and high. The design is well known and tested on french boards. http://audioclone.free.fr/new baby.gif
I am not sure, I don't know much about series crossovers, but it may be that the 6.8 ohm and 30 uF leg in parallel with the drivers and crossover provides the baffle step function. But the bottom line really is if it is already a designed and tested crossover for these drivers you should be all set.
00940 said:
He he he what a coincidence, I have built the ASA Baby clone over the last month, with the parallel crossover. It sounds surprisingly good. Unfortunately I have no idea what Vifa model "HT 270" is and googling it yielded no clues so I used the D27-35.
http://audioclone.free.fr/asababy.html
Not being sure if the driver I'm using is the one the crossover was designed for bugs me a bit though. Id there any way of finding out what the model numbers Vifa uses in France and the Netherlands (those are the countries with alternative model numbers that I'm aware of, there are probably more) correspond to in, say, the Solen and Madisound catalogs?
MJK : thanks. I'll let you know how this thing ends 
Willitwork : John Kreskovsky published a crossover for the P17WJ and the D27TG : http://www.audiodiycentral.com/sd200_johnk.shtml
I prefer to use the serie crossover from Aldo (audioclone.free.fr) as it was designed for and tested on a bigger box, with a baffle more similar to mine.
Willitwork : John Kreskovsky published a crossover for the P17WJ and the D27TG : http://www.audiodiycentral.com/sd200_johnk.shtml
I prefer to use the serie crossover from Aldo (audioclone.free.fr) as it was designed for and tested on a bigger box, with a baffle more similar to mine.
00940 said:
Thanks, John K's crossover was the first one I tried on the Baby (with D27 mod), I built the speakers that crossover was designed for some time back so I already had the crossovers on hand. They work great in the sealed boxes but not so good with the vented Baby, imaging wasn't as accurate and bass would cut off pretty steeply below 70Hz. Using the parallel crossover from the French site fixed these problems.
I know and respect John K's prowess with crossovers but one of his stated goals with the sealed box was that the project should cost no more than $200.00 and this constraint may not have allowed him to build a crossover as accurate as he would have done on a beefier budget.
Sadly the French designer of the crossover for the Baby (Aldo) has left a few days ago to work in Dakkar (Senegal). He's a bit hard to contact right now.
What kind of P17 do you have ? If they're P17WG, there's a detailled project here : http://raymondaudio.nl/
What kind of P17 do you have ? If they're P17WG, there's a detailled project here : http://raymondaudio.nl/
00940 said:
I have P17WJ's, 8-ohm version. Unfortunately the differences with WG are quite major and would preclude my using of the WJ in a project designed for the WG I presume? Judging from the smaller magnet and higher Vas the WG was designed to perform best at lower frequencies...
EDIT I noticed that Raymond's published T/S specs for the WG are much closer to the WJ than the official spec sheet. Perhaps this could work after all, with some tweaking (less damping). I like his design a lot. Thanks for the link
Yes, I had seen those pipes. It was one of the many designs I've been busy simulating last week. Compared to the one I settled on, they're apparently way more efficient but the expected -3dB point is at least 20hz higher. No big deal as I will be using solid state amps.
I confess I've not tried seriously to model TQWT's to see if the frequency response could be improved, as I followed Bob Brines' article on TL design, in which he states that he "finds no reason to use the TQWT taper unless a customer demands it. The straight and conventional taper always give better results. Also, drivers with a Qts < 0.35 tend to work best in a straight TL, while drivers with Qts > .040 work best in a tapered TL."
For WAF issues, they probably could be easily folded btw.
I confess I've not tried seriously to model TQWT's to see if the frequency response could be improved, as I followed Bob Brines' article on TL design, in which he states that he "finds no reason to use the TQWT taper unless a customer demands it. The straight and conventional taper always give better results. Also, drivers with a Qts < 0.35 tend to work best in a straight TL, while drivers with Qts > .040 work best in a tapered TL."
For WAF issues, they probably could be easily folded btw.
I'm awfully conventional. I like "boxes". My favorite speakers (as far as design is concerned) are the Totem floorstanders, such as the Forest.
I like "boxes". My favorite speakers (as far as design is concerned) are the Totem floorstanders, such as the Forest.An externally hosted image should be here but it was not working when we last tested it.
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