Usher 9845 2" Midrange

[wigginjs]

Anyone have experience or measurements of this driver? Looks very interesting to me. I'm imagining something like a TMWW with Peerless 810921 and Usher 8945P/A. Would be an awesome 3 or 3.5 way I think. Any comments? Perhaps from Jay_WJ?


http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=276-620

 

[Jay_WJ]

It should be a decent performer though we haven't seen a distortion test.

The flange is a little larger than I'd like. A Duelund 3-way (or 3.5 way) xover should be possible. 8" woofer can take advantage of (and justify) the use of a dome midrange.

Personally, however, I don't see a reason for preferring this midrange to the Dayton RS52.

 

[wigginjs]

I don't see a reason for preferring this midrange to the Dayton RS52

Textile dome? I don't really know if this has any real scientific bearing, but it seems that most people don't like to mix metal and paper / fabric...

Also, what is a "Duelund xover"? Don't they simply manufacture components or is there a "Duelund" topology?

 

[Jay_WJ]

Textile dome? I don't really know if this has any real scientific bearing, but it seems that most people don't like to mix metal and paper / fabric...

Also, what is a "Duelund xover"? Don't they simply manufacture components or is there a "Duelund" topology?

If it is an aesthetic reason, I understand, but the RS52 is one of the lowest distortion 2" domes available to us. According to its harmonic distortion profile, it won't sound metallic at all in its frequency band we use it for.

What I mean by the Duelund xover is a type of 3-way xover, which is a good candidate when two Fc's are close in a 3-way. When Fc's are far enough, it becomes close to LR2 3-way.

 

[wigginjs]

What I mean by the Duelund xover is a type of 3-way xover, which is a good candidate when two Fc's are close in a 3-way.

Hmm... So, which Fc's are close? The mid and the tweeter? The two woofers? Also, what are the characteristics that differentiate a Duelund crossover from an LR2 crossover? Does a Duelund crossover have a particular slope?

 

[Jay_WJ]

Only two Fc's in a 3-way: woofer-midrange and midrange-tweeter. Theoretically, LR2 is only a 2-way filter. When Fc's are far apart in a 3-way, LR2 3-way's intended all-pass property holds good approximately. But when Fc's are close (e.g., 800 Hz and 2 kHz), it doesn't. The Duelund 3-way filter was derived as a 3-way xover (i.e., not just a combination of separate 2-way filters). It is a theoretical generalization of LR4 2-way and (what we call) LR2 3-way. When two Fc's coincide, the Duelund 3-way becomes LR4 2-way with only a single Fc (the need for midrange goes away), and when two Fc's are far apart, it becomes approximately a combination of separate LR2's.

Its slopes of a midrange is 2nd order and the slopes of woofer and tweeter vary depending on how far apart the two Fc's are.

 

[DcibeL]

If you're using the Peerless 810921 and Usher 8945 I don't really see the need for the midrange. If you use the midrange, you can cross at a higher frequency to a cheaper tweeter, and possibly be able to use a larger woofer for deeper bass.

 

[wigginjs]

Ok, I think I see where some confusion might be. I was thinking Fc referred to the resonant frequency of a closed box system. You seem to be using it to refer to a crossover point? Either way, have you ever considered a system using two 8945As a mid dome (RS52, etc.) and the 810921? I suppose this system is actually starting to sound fairly similar to Zaph's ZDT3....

 

[wigginjs]

If you use the midrange, you can cross at a higher frequency to a cheaper tweeter, and possibly be able to use a larger woofer for deeper bass.

Yep I think you're right. Seas 22TAFG seems to have remarkably low distortion above ~2.5KHz and it's only $27. But, with regard to the bass the 8945A seems to have very low distortion, so I believe two of those would work quite well.

 

[Jay_WJ]

Ok, I think I see where some confusion might be. I was thinking Fc referred to the resonant frequency of a closed box system. You seem to be using it to refer to a crossover point? Either way, have you ever considered a system using two 8945As a mid dome (RS52, etc.) and the 810921? I suppose this system is actually starting to sound fairly similar to Zaph's ZDT3....

Yes, I have. But when we use a good dome midrange, the strength of the 8945P/A (low distortion midrange above 500-600 Hz) won't be used. Below this range, the RS180 will do an excellent job, too, and the RS225 will do an even better job.

 

[Jimmy154]

I'm also looking at using the Usher 9845 mid.

I don't know how the distortion compares to the Dayton RS52.

Here are the distortion graphs for the two:

http://www.zaphaudio.com/smalltest/Dayton-RS52-HD.gif

http://www.diymobileaudio.com/forum/showthread.php?t=14

The problem for me is how to compare them. The Usher is playing at 96 db during the test and the Dayton SPL during the test is unknown to me at this time. Also the methods/setup might be different, maybe, I don't know. Both their F1s are hovering roughly around -10 db. I don't know what that means. I assume the F1 is a guide on how to judge the distortion lines, with respect to the F1 of course, but I'm not sure.