Great D.O.T.D. @ P.E. TB 5.25 woofer...

[critofur]

This was already the "Value Leader" of Zaph's ~ 5.5" woofer roundup at $25, now, it's on sale for $15 ea!

http://www.parts-express.com/pe/psho...td&orefer=dotd

I'd been planing on buying some for a while now and just hadn't gotten to it. Tonight, I was ready to go "check out", I had some "in my cart" over at Amazon.com 'cause I had some gift certificates to use and when I saw the price I was pleasantly very surprised and thought it must be a pricing glitch or something. I headed over to partsexpress.com to check it out then saw on the front page "deal of the day". So, I ordered four instead of two

Heh, I'm going to be building some great sounding speakers for a total of $25 in parts for each speaker (I got a pile of capacitors and a few nice baltic birch plywood boards as a gift, the tweeters I'll use I got for $10).

[14G-Dutch^]

I looked @ TB's website, the driver changed and is now different, not shielded for one, and the FR is supposedly up to 9K now. I got 8 of them. gonna do a .33 Cf vented, tuned to 60 Hz. I will probably cross them @ 3500 to my Vifa D27TG-05-06 tweeters.

Was screwing around today, and for the fun of it I popped them into a .25 Cf Sealed enclosure. Fairly large output in the bass area, didn't get very low, but these were designed for vented anyways.

Jon

[Jay_WJ]

Originally posted by 14G-Dutch^
I looked @ TB's website, the driver changed and is now different, not shielded for one, and the FR is supposedly up to 9K now. I got 8 of them. gonna do a .33 Cf vented, tuned to 60 Hz. I will probably cross them @ 3500 to my Vifa D27TG-05-06 tweeters.

Was screwing around today, and for the fun of it I popped them into a .25 Cf Sealed enclosure. Fairly large output in the bass area, didn't get very low, but these were designed for vented anyways.

Jon

They should work for both sealed and vented. When used in a sealed box, they will give a perfect bass rolloff to be used with a subwofer at 80 Hz crossover setting on a HT receiver.

.33 cu ft will be a bit less than ideal for this driver. .5 cu ft will be better for vented.

With the Vifa, I'd shoot for 2 k to 2.5 kHz LR4, or 2.5 k to 3 kHz LR2.

[John L]

Jay, is your crossover you published at PE still up to date?

[Jay_WJ]

My xover simulations used Zaph's old data for W5-704S.

But according to the TB's new spec sheet, the 704D's frequency response and impedance curve are very similar to the 704S's. I actually compared the 704D's measured impedance curve to the one I used for modeling. They are very, very close up to 2 kHz. Since I used a Zobel in the xover, minimal differences at higher frequencies won't matter, either. As for the FR, usually TB's published FR is a few dB higher than actual one. The 704D FR on the spec sheet is very similar to Zaph's 704S FR except only 1 to 2 dB higher. So, my simulation should be pretty much in the right ball park.

A major difference between the new and old drivers is in their T/S parameters. The old one was suitable for a sealed design with high Qts, but the new one, according to a few sample measurements, has a bit less Qts making it suitable for both sealed and vented. But a vented design still requires a bit larger volume than people may want for a 6" driver.

-jAy

[14G-Dutch^]

Originally posted by Jay_WJ


They should work for both sealed and vented. When used in a sealed box, they will give a perfect bass rolloff to be used with a subwofer at 80 Hz crossover setting on a HT receiver.

.33 cu ft will be a bit less than ideal for this driver. .5 cu ft will be better for vented.

With the Vifa, I'd shoot for 2 k to 2.5 kHz LR4, or 2.5 k to 3 kHz LR2.

Jay,

Why .5? WinIsd models what looks better to me, admittedly a noob, with .33, which gives an f3 of 61Hz. The .5 seems to give a lower response capability, but to me it looks like I would be losing almost 2 Db between there and gradually less on up to 100Hz.

Would you mind explaining your idea to me?

Also, why would you cross this tweeter that low? It has an Fs of 1000Hz

Vifa tweeter specs

Vifa recommends 3500Hz, and the woofer is pretty clean up till nearly 6k, so I am not seeing a reason to cross that low. Again, I am not well versed on all the ins and outs of design. I am sure you have a good reason for these thoughts, I just can't see them.




Thanks,

Jon

[Jay_WJ]

Originally posted by 14G-Dutch^

Why .5? WinIsd models what looks better to me, admittedly a noob, with .33, which gives an f3 of 61Hz. The .5 seems to give a lower response capability, but to me it looks like I would be losing almost 2 Db between there and gradually less on up to 100Hz.

Would you mind explaining your idea to me?

T/S values on the spec sheet aren't accurate. Take a look at:

http://www.htguide.com/forum/showthr...t=28829&page=1

Find measured T/S parameters in posts #22 and #30. Try to use them in your WinISD sim.

Also, why would you cross this tweeter that low? It has an Fs of 1000Hz

Vifa tweeter specs

Vifa recommends 3500Hz, and the woofer is pretty clean up till nearly 6k, so I am not seeing a reason to cross that low. Again, I am not well versed on all the ins and outs of design. I am sure you have a good reason for these thoughts, I just can't see them.

Again, don't rely on the manufacturer's spec sheet. See Zaph's distortion measurement:

http://www.zaphaudio.com/tweetermishmash/D27SG15-HD.gif

The D27TG05 performs identical to the D27SG15. According to Zaph's HD sweep, this tweeter is a very nice performer. 2.0 kHz LR4 is no problem with it. Fs at 1 kHz won't matter, either, for LR4 application even without a notch filter. You can simply use an L-pad before the tweeter and it will take good care of the resonance. For LR2, you may need a notch filter.

Considering the 6" woofer's beaming and CTC spacing between the drivers, a lower xover point will give a more robust vertical polar response.

[John L]

Jay, is this one still good to go, using the Vifa D26NC55? Or does it need modifications considering the new types?

[Jay_WJ]

Originally posted by John L
Jay, is this one still good to go, using the Vifa D26NC55? Or does it need modifications considering the new types?

Strictly speaking, I can't be 100% sure till I see a FR measurement of the new 704D. But I'm pretty confident that it is good to go with tweaking only the R9 value to adjust the tweeter level.

[John L]

thanks. This is the one I am going to go with. I like that idea of the TB tweeter, but the sticky surface is a turnoff, as John K mentioned.