Usher/BG idea

[stinems]

I've had my eye on the Usher 8137a driver for a while now, but haven't seen it used much. Talk about low distortion...

http://www.partsexpress.com/pdf/296-616.pdf

Since the 8137a compares favorably versus even the 8945P (a driver which Zaph recently measured with similar results as shown by mfg specs) in terms of distortion by Usher's spec, I'm guessing Zaph would see the same results.

Difficulty with the 8137a: Qts of .45ish and VAS of 60L make for a largish (tho not inconceivable) vented box. Also, with FR nastiness starting ~1100 hz, conventional crossovers are a pain, and pretty much limits it to 3 way use.

Unless....
You use something like the BG NEO8. Yet another driver I haven't seen used. Not the flattest response, but it opens up all sorts of possibilities being able to cross as low as 600 to 700 hz, especially if you're thinking two way. And being a purely resistive load makes it easy on amps.

Difficulty with BG NEO8 PDR: Not a flat response (requires a notch filter at 12khz), must tune the enclosure right to get the extended midrange response, doesn't have an extended high end.


With these drivers in mind, anybody think its possible to pull off a 2.5 way tower, maybe 100L vented to 32 hz or so, crossed at 900hz? The BG NEO 8 is a big question mark to me. Has anybody actually heard it in action?

I think with some care it could be done. Any thoughts?

~Sam S.

[Rick Craig]

I've had my eye on the Usher 8137a driver for a while now, but haven't seen it used much. Talk about low distortion...

http://www.partsexpress.com/pdf/296-616.pdf

Since the 8137a compares favorably versus even the 8945P (a driver which Zaph recently measured with similar results as shown by mfg specs) in terms of distortion by Usher's spec, I'm guessing Zaph would see the same results.

Difficulty with the 8137a: Qts of .45ish and VAS of 60L make for a largish (tho not inconceivable) vented box. Also, with FR nastiness starting ~1100 hz, conventional crossovers are a pain, and pretty much limits it to 3 way use.

Unless....
You use something like the BG NEO8. Yet another driver I haven't seen used. Not the flattest response, but it opens up all sorts of possibilities being able to cross as low as 600 to 700 hz, especially if you're thinking two way. And being a purely resistive load makes it easy on amps.

Difficulty with BG NEO8 PDR: Not a flat response (requires a notch filter at 12khz), must tune the enclosure right to get the extended midrange response, doesn't have an extended high end.


With these drivers in mind, anybody think its possible to pull off a 2.5 way tower, maybe 100L vented to 32 hz or so, crossed at 900hz? The BG NEO 8 is a big question mark to me. Has anybody actually heard it in action?

I think with some care it could be done. Any thoughts?

~Sam S.

The Neo8 (original or PDR version) is a poor tweeter.

[Feyz]

Difficulty with the 8137a: Qts of .45ish and VAS of 60L make for a largish (tho not inconceivable) vented box. Also, with FR nastiness starting ~1100 hz, conventional crossovers are a pain, and pretty much limits it to 3 way use.

I would try something like 40lt vented box. Sure this gives higher F3 (39Hz vs 27Hz), but for most of the music there is not much bass energy in those regions. I had looked at a couple of classic, jazz, pop CD track songs's peak and average running window spectrum a while ago, and both peak and average bass came out to be higher than 40Hz, most bass energy is around 50-200Hz region. With a smaller 40lt 35Hz tuned vented yields less excursion from 32Hz to 100Hz vs 60lt box, therefore less distortion and more power handling there where it is more important. 35Hz tuning causes some peaking but with some extra damping inside the box this can be reduced, and that will also help with midrange clarity.

The FR of this driver is challenging, but I tend to think it could be mated to a 1" dome, with not much trouble. Only if I had the time and means these days, I would sure try this, since I heard many say this can't won't work, it looks like a challenge to take on

[stinems]

The Neo8 (original or PDR version) is a poor tweeter.

Any particular reason why you think that? I'm groping for a reason NOT to try this! Some compromises would probably have to be made, but it could also have some interesting strengths as well.

I guess I'm not sold on the idea that a flat anechoic, on-axis response is such an imperative. By the time you get a speaker in a real room and worry about dispersion and power response, I believe minor FR flaws can be overlooked. I will concede the NEO8's 12khz monstrosity is definitely something that needs to be addressed

Personally, I can't hear above 16khz anyway.


~Sam S.

[Mudjock]

I've heard of some who were satisified with the Neo8 in dipole configuration as a tweeter. As a monopole, it is much more directional than a conventional tweeter (lower power response up high).

[Jed]

How about an usher 8", dome mid and tweeter? Might not be as challenging to design as the usher 8" 2-way, but nice sounding results. I'm impressed with how low distortion the usher mid dome specs are. Too bad it has that gargantuan frame. Limits one to a lowish 3k crossover to the tweeter.

[stinems]

Heh, now we're shifting the idea entirely.

Maybe it IS asking too much for the 8137a to be used in a 2way. I had the chance to hear it Paul O Neal's three way at DIY Iowa this year, passive radiator alignment IIRC, and it had the best sounding bass in the entire event IMHO. Plus it looks badass with the woven kevlar/carbon fibre.

I'd really like to try out the BG planars, and if a 3 way is what is called for, you could get away with using the NEO3, which seems to have gotten more respect than the NEO8.

I'm not sold on the usability of the Usher dome mid. I guess the Dayton RS dome could be a possibilty, tho I have yet to actually hear it. I still think Jim Holtz's old 3 way using the Morel dome mid (with the yellow coned Focal drivers) has some of the best midrange I've ever heard, so that's another option...

Bah, dang midrange, always the most difficult part...

~S

[Jed]

Heh, now we're shifting the idea entirely.

I didn't mean to discourage you at all. In fact, you might page TacoD, since he developed a speaker with that Usher 8". I'm pretty sure he used it in a 2-way. Maybe he can shed some light on this topic with his experiences.

[Rick Craig]

Any particular reason why you think that? I'm groping for a reason NOT to try this! Some compromises would probably have to be made, but it could also have some interesting strengths as well.

I guess I'm not sold on the idea that a flat anechoic, on-axis response is such an imperative. By the time you get a speaker in a real room and worry about dispersion and power response, I believe minor FR flaws can be overlooked. I will concede the NEO8's 12khz monstrosity is definitely something that needs to be addressed

Personally, I can't hear above 16khz anyway.


~Sam S.

There are two problems with the Neo8 as a tweeter. The first one is the resonance peak in the top octave and the other is the poor off-axis response in the top octave. The PDR versions of the 3 and 8 add a resistive fabric to the outer edges to make the radiating area more narrow. With the 3PDR it helps but the top octave off-axis is still performs worse than most 1" domes. If you want to use the Neo8 I would switch to a 3-way.

[TacoD]

I didn't mean to discourage you at all. In fact, you might page TacoD, since he developed a speaker with that Usher 8". I'm pretty sure he used it in a 2-way. Maybe he can shed some light on this topic with his experiences.

I used the 8137K which is listed as a 8" driver. I bought these to use them <200 Hz so I haven't tried a two way. Although my measurements show that this is certainly a possibility. In fact in the german magazin HobbyHifi they designed a 2way with the Usher 8137K and the Usher 9950 tweeter.

At the moment I'm a bit occupied with the more expensive stuff, but maybe in 2007 I will do a two way with the Usher. I've a XT25 and a scan 9800 on the shelf which both can be crossed with the Usher. My main problem is the woodwork, I'm hating it (combination of lack of skill, lack of tools and lack of space).

[stinems]

...With the 3PDR it helps but the top octave off-axis is still performs worse than most 1" domes....

OK Rick, I will admit the NEO8 is probably too snaggletoothed, and probably not worth the drama, especially as a tweeter.

But I'm not seeing bad off axis performance in the NEO3PDR.

http://www.partsexpress.com/pdf/264-716s.pdf

Seems to me, most 1" domes are -10dB at 20khz, 30deg off axis.

The NEO3PDR looks to be -6dB at 20khz, 30 deg off axis. And unlike most domes, 60 deg off axis performance is almost 100% up to 12 khz.

I think what I'll do is use the NEO3PDR in my next project, a computer speaker/satellite project, and see how they behave before tapping them for a reference grade 3 way.

Really appreciate everyone's input!
~Sam

[Rick Craig]

OK Rick, I will admit the NEO8 is probably too snaggletoothed, and probably not worth the drama, especially as a tweeter.

But I'm not seeing bad off axis performance in the NEO3PDR.

http://www.partsexpress.com/pdf/264-716s.pdf

Seems to me, most 1" domes are -10dB at 20khz, 30deg off axis.

The NEO3PDR looks to be -6dB at 20khz, 30 deg off axis. And unlike most domes, 60 deg off axis performance is almost 100% up to 12 khz.

I think what I'll do is use the NEO3PDR in my next project, a computer speaker/satellite project, and see how they behave before tapping them for a reference grade 3 way.

Really appreciate everyone's input!
~Sam

The Neo3PDR is acceptable, just not as good off-axis as what I'm used to with the Fountek ribbon. It will cross lower than the Fountek so in some 2-way designs that can help.