It was indeed "sound" reasoning. 🙂
John has built a number of OB speakers with dome tweeters. My favorite was a set that used 2 pro 18" per side, with a Beta 12LTA for the midrange crossed to a dome tweeter. Great speakers.
And then there were the "Jokes" with the same 18" woofer (1 per side) and a dome tweeter. Yes, a 2-way with a pro 18 and a dome tweeter. It worked!
John liked the Peerless woofer, and at the time it was not too $$$. So naturally he made a not too hard, not too expensive OB with it. The Seas 27TDFC tweeter was a natural choice. Good tweeter, good price, could almost play loud enough. And John probably had a few lying around. A simple 4 element crossover was built and Voila! The Manzanita was born. That was 8 years ago. You can see the originals in post number 12.
I liked it, but never thought the 27TDFC really had the cajones to keep up with the woofer. At least not as far down as we were forcing it to play. So on my speakers I swapped in the Monster Truck of tweeters, the Scanspeak D3806/8200. Superb driver, been around for years, not cheap. For me the D3806 worked great and matched up with the woofer much better than the 27TDFC.
But at the time the D3806 had gotten hard to find and was still expensive. $175 each, these days.
John and I talked a lot about finding a cone tweeter that could play low enough to cross well with the Peerless woofer yet still go up high. We couldn't find anything. Four years into the project, John surprised us with the Vifa TC9FD18-08. Don't know where he came up with that one, but it stuck. And it fills the bill.
You really DO need to adjust the crossover, tho. When I first built them I found John's crossover too rolled off at the top for my room. The Vifa response really gets bright at the top, but John had tamed it too much for my room. I had to change the trap inductor and resistor some. Tweak that inductor!
There you have it. The Peerles woofer remains the heart of the speaker in the original version. It was the quest to find a mid/tweeter to match it that led us to the Vifa.
John has built a number of OB speakers with dome tweeters. My favorite was a set that used 2 pro 18" per side, with a Beta 12LTA for the midrange crossed to a dome tweeter. Great speakers.
And then there were the "Jokes" with the same 18" woofer (1 per side) and a dome tweeter. Yes, a 2-way with a pro 18 and a dome tweeter. It worked!
John liked the Peerless woofer, and at the time it was not too $$$. So naturally he made a not too hard, not too expensive OB with it. The Seas 27TDFC tweeter was a natural choice. Good tweeter, good price, could almost play loud enough. And John probably had a few lying around. A simple 4 element crossover was built and Voila! The Manzanita was born. That was 8 years ago. You can see the originals in post number 12.
I liked it, but never thought the 27TDFC really had the cajones to keep up with the woofer. At least not as far down as we were forcing it to play. So on my speakers I swapped in the Monster Truck of tweeters, the Scanspeak D3806/8200. Superb driver, been around for years, not cheap. For me the D3806 worked great and matched up with the woofer much better than the 27TDFC.
But at the time the D3806 had gotten hard to find and was still expensive. $175 each, these days.
John and I talked a lot about finding a cone tweeter that could play low enough to cross well with the Peerless woofer yet still go up high. We couldn't find anything. Four years into the project, John surprised us with the Vifa TC9FD18-08. Don't know where he came up with that one, but it stuck. And it fills the bill.
You really DO need to adjust the crossover, tho. When I first built them I found John's crossover too rolled off at the top for my room. The Vifa response really gets bright at the top, but John had tamed it too much for my room. I had to change the trap inductor and resistor some. Tweak that inductor!
There you have it. The Peerles woofer remains the heart of the speaker in the original version. It was the quest to find a mid/tweeter to match it that led us to the Vifa.
Thanks for that! I've been going back through the thread looking for that change! I'll remember to tweak! I have seen a few posts here and on
'The best OB speaker I've heard" thread on the Circles forum concerning the top end tweaking.
Russellc
'The best OB speaker I've heard" thread on the Circles forum concerning the top end tweaking.
Russellc
A question concerning the Woofer trap John discussed, does this post (#1059 ) show it correctly?
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-22.html#post3931863
I was a little confused about the response in John's next post ( #1060 )
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-22.html#post3933056
" I do add in the crossover series resistances in the formula showing the speaker impedance to be about 8.8 ohms. And we save a $5.00 resistor doing it this way".
At first I thought he meant that he added another resistor, but then comments it saves one?😕
Russellc
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-22.html#post3931863
I was a little confused about the response in John's next post ( #1060 )
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-22.html#post3933056
" I do add in the crossover series resistances in the formula showing the speaker impedance to be about 8.8 ohms. And we save a $5.00 resistor doing it this way".
At first I thought he meant that he added another resistor, but then comments it saves one?😕
Russellc
He means that he takes into account the DCR of the inductor. It acts as a resistor, of course. No need to add that resistance in if it's already there. 🙂
That's all I could figure, but I want to do it right! So the illustration is correct then? I suppose it is or you would have mentioned it here or after that post!
Thanks for the response! I am getting ready to order the last of the crossover parts, and plan to get to building right after the Thanksgiving day Holiday.
Russellc
The TG9 won't give you any SPL advantages compared to the TC9 paper coned Vifa. But it does have advantages in the upper HF response.
TC9 off axis measurements:
TG9 off axis measurements:
P.S. not my own measurements, just some data acquired while researching for my own project. Notice the small difference in sensitivity as well. You'd have to re-check the crossover and see if changes are needed.
The above plot is from the 8 ohm TG9 driver. It isn't terribly expensive and definitely worth a shot. As long as you can still get your hands on it.
Thanks for the plots. The TG does look better controlled up top. I wonder about power handling?
I expect the Vifa's to be quite similar in power handling. The TC9 being only a hair more sensitive than the TG9.
Did you know even a Kevlar coned Vifa exists? Another sibling 🙂.
http://www.diyaudio.com/forums/full-range/282412-tpy03w06o0111-k-oem-black-tg9fd.html
And of coarse the higher grade Scan Speak 10F is also kind of a relative and the one with the best papers, though in spec's it is way different driver than all of the little 3.5" Vifa's.
Did you know even a Kevlar coned Vifa exists? Another sibling 🙂.
http://www.diyaudio.com/forums/full-range/282412-tpy03w06o0111-k-oem-black-tg9fd.html
And of coarse the higher grade Scan Speak 10F is also kind of a relative and the one with the best papers, though in spec's it is way different driver than all of the little 3.5" Vifa's.
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Since apparantly no-one's done it, I decided to give it a go! Drivers are shipped and I'll let you know the results!
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Joined 2009
Paid Member
Exactly! - without a project like this you'd have no excuse to buy a nice router 😀
It will be handy for hundreds of other project ideas yet to come - go for it - make sure you buy a router template thingy that screws to the base of the router and allows you to route holes of different sizes
Hi,
Would it be possible to remove the wings and instead extend the baffle Width the same amount?
I guess it will Work for the bass driver, but will the vifa output be seriously affected?
🙂
Edit: An alternative could also be to have the wings in 45 degree angle?
Would it be possible to remove the wings and instead extend the baffle Width the same amount?
I guess it will Work for the bass driver, but will the vifa output be seriously affected?
🙂
Edit: An alternative could also be to have the wings in 45 degree angle?
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The distance from listener to front and distance to rear of cone are different for the rear pointing wings and the side pointing wings.
It's that distance difference that determines the roll off frequency.
I was told a long while back that there was no EQ needed for this Open Baffle.
But there is and it would need to be changed if the front & back travel distance were altered.
It's that distance difference that determines the roll off frequency.
I was told a long while back that there was no EQ needed for this Open Baffle.
But there is and it would need to be changed if the front & back travel distance were altered.
Correct, the "EQ" is built into the crossover. That will need to be changed is baffle size changes. Jamming mine into the corners of a lava cave meant that the low pass inductor had to be dropped to 4 mH.
I bought a circle jig from PartsExpress a while back for just such an occasion!
Russellc
Well, not having router, I have never tried it out! Been meaning to buy router for some time, amplifier building intruded.
Russellc
Russellc
I like mine... I've cut a lot of holes for drivers in my day. It's a little bit fiddly to find the 'right' radius hole from the back side, but if you're careful, it's just fine. It does make the whole process easier, and cleaner looking.
I have some other suggestions regarding this matter, as another coil in series with the woofer would be problematic (RDC):
#1: Instead of the trap Circuit (15uF//0,4mH), you can try with a Zobel directly accross the woofer terminals: R+C = 6R8+22uF.
This prevents the rising impedance and gives better damping and no extra coil added i series with woofer to degrade performance.
#2: A cheaper alternative would be to make the 20mH coil a part of the trap. This is done by connecting a 330nF capacitor in parallel with the 20mH.
I haven't tested theese yet, but they will be on my to-do-list 🙂