Dynalab sale speaks at Parts Express

PE has got some 8" Dyanlab 4 ohm woofers, Part # 299-4004, for sale for less than $10 each and some 1" Mylar 8 ohm dome tweets, Part # 299-4006, for $3.88 each. For s*#ts and giggles I bought 4 of the woofers and 2 of the tweeters. I was thinking of putting 2 woofs and a tweet in each of a pair of repurposed boxes that are 1.3 cubic feet net, with a Dayton audio 3500 hz, 12 db/oct crossover. MTM Sealed box. Probably will need a BSC circuit. I don't expect "Ultrafi." They are for a stepson whose current music maker is one of those godawful Bluetooth gadgets. I'm gonna try to have them done for Christmas. Suggestions?
 
Hi,
perplexity arises when seeing the 3.5 kHz crossover; a 1 kHz tone is already 'high' and when played by two voices ( the woofers one next to one) it would produce some irregularities...
The obvious answer would be to add a midrange to overcome the issue.
Or choose a tweeter that plays as low.
I made a nice sounding speaker with a 8" plus a 2" with a 8" waveguide crossed at about 1 kHz. The coil used for LP was 3.5 mH ( 8 Ω load ) and that included BSC. The waveguide is a broken speaker, just the cone.
See also Improving the Linkwitz Phoenix? for double 8"+ tweeter
 

Lojzek

Member
2012-02-10 12:12 pm
Croatia
PE has got some 8" Dyanlab 4 ohm woofers, Part # 299-4004, for sale for less than $10 each and some 1" Mylar 8 ohm dome tweets, Part # 299-4006, for $3.88 each...Suggestions?

Great stuff for the fun of DIYing. If you had a usb measurement mic and a simple impedance measuring jig, this could potentially play quite alright. If you were to prepare frd's and zma's as described by J.Bagby in his white paper, and present these here, anyone could load files to a simulator and help you with crossover. You would purchase bits after succesfully simulating it.
 
See, as I was mentioning in another thread about my old Infinities RS 4001, some things remained, like the rheostats and some coils, and
The coil used for LP was 3.5 mH ( 8 Ω load ) and that included BSC.
those were the coils for LP at 500 Hz ( by the datasheet) on 4 Ω load.
So it must be 1 kHz for 8 Ω load, right?
:rolleyes:

1 kHz crossover point for a Vifa 8“, 6 dB/Oct
Meet approximately* the directivity index at 1 kHz to make a specular/inverse slope for the tweeter and make it 2nd second order for ...>same as BSC:razz:

*also approximatively

This I call the right design technique which necessarily comes before the need to play with .fzr & .zma numbers :D:eek:
 
1 kHz crossover point for a Vifa 8“, 6 dB/Oct
Meet approximately* the directivity index at 1 kHz to make a specular/inverse slope for the tweeter and make it 2nd second order for ...>same as BSC:razz:

*also approximatively
The only (mid) tweeter that seems to work, is a monacor SPX-20 ( 21 is 8Ω and allows some less 'abuse' IIRC ) which is 4 Ω
which is also the faultyness of this project, because of the low power -relatively- supportation ( but compared to the 50W woofer is not that much)
and the low Z above 1 kHz which causes stress for the amp. My vintage amps (used to ) get ridicously hot :eek::flame:

Another stress is the waveguide with a 2" throat but nowadays there's the 3D printer :p but you're still costrained ( a little bit - approximately :eek: ) by the CTC between the two sources - you would want three but (AND/OR) MTM (Ultra-fi) has MORE conditions to satisfy ;)
 
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