A good tweeter match for Usher 8945s - AVS Forum
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post #1 of 18 Old 11-24-2013, 04:19 PM - Thread Starter
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I have been doing a little research in speaker building in the last two or three weeks and I'm not much better off. I had to dump 6 months of childhood memories so I could somewhat absorb the first chapter in the Dickason LDC 7 book. TMI ! I decided to go with a proven arrangment, but that is not so easy either. I mentioned before that I was considering the Vifa XT25 "60" tweeter to go with two Usher 8945a woofers. I decided on building a two way MTM sealed floor standing speaker pair. I had some unfavorable responses about this speaker combo and I would like to bring it up for discussion. It seems that alot of folks use and like this setup but on the other hand just as many folks dont like it. Can someone help me with why this may not work well? Without spending a lot more cash, what other tweeter options do yall suggest might be a better fit for the Ushers. I'm pretty well set on the 8945s because they seem to be a really good speaker especially for the price. I'm also concidering an active X Over plate amplifier but have not committed to it yet. They will be used for music mostly. I'm ready to purchase the drivers now, but I need more confidence. Thanks again Mike D.
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post #2 of 18 Old 11-25-2013, 03:10 AM
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Can you give us some more info on the Usher mid-range driver? Size? Crossover frequency? Sensitivity?

It will be hard to suggest a tweeter without some additional information.
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post #3 of 18 Old 11-25-2013, 10:21 AM
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If you don't know how to design a speaker I would suggest building Paul Kittinger's Marcato using the Usher 8945P (I think the A is a drop in though, you could ask him over at partsexpress forum) and BG Neo3 planar tweeter. Paul is the guy who did the transmission line designs for Salk and Dennis Murphy.

If you are deadset on doing it yourself, I would suggest the Scanspeak 2608/9130 HDS or Dayton RS28A. Both sound very good, the Scan a bit more spacious and natural, but the Dayton is better behaved and can be pushed lower. Try either on a waveguide from http://pellegreneacoustics.com/waveguides.htm.

~Brandon


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post #4 of 18 Old 11-25-2013, 01:32 PM - Thread Starter
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Usher 8945 a

Nominal Diameter 7"Power Handling (RMS)80 Watts
Power Handling (max)90 WattsImpedance8 ohms
Frequency Response35 to 8,000 HzSensitivity87 dB 2.83V/1m
Voice Coil Diameter1.625"
THIELE-SMALL PARAMETERS
Resonant Frequency (Fs)35 HzDC Resistance (Re)5.8 ohms
Voice Coil Inductance (Le)0.46 mHMechanical Q (Qms)1.96
Electromagnetic Q (Qes)0.37Total Q (Qts)0.31
Compliance Equivalent Volume (Vas)1.21 ft.³Maximum Linear Excursion (Xmax)6 mm

I've heard that the Vifa XT 25 works well with active X Overs but not so good with passive. I dont mind spending more for the tweeter, I just want a good match for the Ushers with passive X Overs. I dont mind copying a previous design if I can find one close to what I want. I like the "Marcato" speaker. I'm not sure about the planar tweeter, I've never actually seen or heard one. And what exactly is a "transmission line speaker".
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post #5 of 18 Old 11-25-2013, 01:58 PM
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All three of the tweeters I mentioned are clearly a step above a Vifa XT25. Transmission lines are an alternative to a conventional vented box. Supposedly smoother and more refined bass. The reason I like them though is the stuffed tapered line often helps damp the backwave and improve the midrange too.

~Brandon


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post #6 of 18 Old 11-25-2013, 02:22 PM - Thread Starter
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The more I look at the Marcato speaker above, the more I like it. That is real close to what I'm looking to build. I was originaly looking for a sealed enclosure but I'm not committed to that. What kind of music would you guys say that a "transmission line" type speaker is best for? I want a speaker that plays loud and has a good punch to it. "70s - 80s" rock mostly. I'm not sure if I like the cosmetics of the enclosure. If I match the inside dimentions and build from 3/4" or 1" MDF would it be the same sounding speaker?
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post #7 of 18 Old 11-25-2013, 02:31 PM
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Yes match the dimensions and you can do whatever you want aesthetically. I think the TL will do fine with anything, as good as any other type of alignment at least. Also Dan Neubecker did the the crossover work, he's probably the best DIY'er you've never heard of. He consistently places at the top of more DIY events than any other designer I can think of, including Dennis Murphy. But most of his designs are omnidirectional, and maybe a little too far out for most people, and so you just don't see many people build his stuff. But clearly he has the skillz judging from the DIY competitions.If you do decide to build them, the partsexpress forum would probably be a good resource since Paul K is an active member there.

~Brandon


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post #8 of 18 Old 11-27-2013, 05:04 AM - Thread Starter
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Thanks augerpro for the Marcato specs. I decided to give it a try. I got in touch with Paul Kittinger (nice guy by the way), and he seems willing to help me if I need it. I looked at some of his other projects. I like his designs and choice of drivers and the neat way he builds his crossovers into the base of the speaker. Good stuff.
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post #9 of 18 Old 11-27-2013, 05:13 PM
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You'll love them! Contact Dan Neubecker also and make sure there won't be any problem using the A versus P usher woofer.

~Brandon


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post #10 of 18 Old 11-27-2013, 05:26 PM - Thread Starter
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Quote:
Originally Posted by augerpro View Post

You'll love them! Contact Dan Neubecker also and make sure there won't be any problem using the A versus P usher woofer.


Good point because I was going to order the "P" model and it seems they have been discontinued. Parts Express are already out of them. How do I get in touch with him?
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post #11 of 18 Old 11-27-2013, 05:44 PM
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he goes by DanN at the partsexpress forum

~Brandon


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post #12 of 18 Old 11-27-2013, 05:58 PM
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The Vifa XT in one of Dave Pellegrene's waveguides might be a nice option. Much better than any flush-mounted tweeter, because the midrange at least will have a chance of sounding right.

I don't know of other dome-tweeter waveguide options in the US. Visaton offers a pretty good one, but I've not seen them for sale in the US.

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"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait

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post #13 of 18 Old 11-28-2013, 09:25 AM - Thread Starter
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I need help with this. I have to put this out there. I was getting ready to order the drivers and parts for building Paul Kittingers "Marcato" speaker system (The link is in augerpro's post above). Well it seems that the Usher 8945 "P" speaker is no longer availible. They do still offer the 8945 "A" which is almost the same woofer. I need some experienced opinions on whether or not I should use the "A" speaker in the place of the "P" speaker. I need to know if I need to scrap the project and find something else or proceed. I know that nobody knows for sure, I just want some opinions on what yall would do. I posted the differences below. Thanks Mike D.

Usher 8945"P" -- Usher 8945"A"

Le: 0.24mH -- Le: 0.46mH
34-5000 Hz -- 35-8000 Hz
Fs: 34 Hz -- Fs: 35 Hz
SPL: 86dB-- SPL: 87dB
Vas: 1.32-- Vas: 1.21
Qms: 2.44-- Qms: 1.96
Qes: 0.39-- Qes: 0.37
Qts: 0.33-- Qts: 0.31
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post #14 of 18 Old 11-28-2013, 01:57 PM
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Paul K simmed it and said the TL performance is nearly identical. So you are good there. My concern is the crossover, they are nearly identical woofer but the Le is just a bit higher on the A, which *may* mean a slight change to component values to get the roll off in the crossover region back to where it should be. We'd all just be guessing if it would or not, but Dan Neubecker can determine if it will make a difference since he has the crossover model.

~Brandon


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post #15 of 18 Old 11-28-2013, 02:12 PM - Thread Starter
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Quote:
Originally Posted by augerpro View Post

Paul K simmed it and said the TL performance is nearly identical. So you are good there. My concern is the crossover, they are nearly identical woofer but the Le is just a bit higher on the A, which *may* mean a slight change to component values to get the roll off in the crossover region back to where it should be. We'd all just be guessing if it would or not, but Dan Neubecker can determine if it will make a difference since he has the crossover model.

I'm a member of the PE forum but for some reason I'm not allowed to post or start a thread. It tells me that a moderator has to authorize my account even after two attepts tp join. So I cant ask Dan N. there.
Parts Express is having a 10% off sale on everything if you buy by tommorrow. I planned on ordering the drivers and XOver parts then. I would really like to decide by tommorrow. Thats some bad luck too. Parts Express offered the "P" woofers deeply discounted a couple of weeks ago and I missed it.
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post #16 of 18 Old 11-28-2013, 04:04 PM
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The frequency response up to about 2k is similar. Above 2k the P version has more output in the breakup region as well as being different in the impedance especially at higher frequencies. I would think this would require some crossover changes. Also the off axis response will likely be different due to the phase plug and could impact the power response which could also require some XO changes, even if just for voicing.
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post #17 of 18 Old 11-28-2013, 04:51 PM - Thread Starter
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Originally Posted by djarchow View Post

The frequency response up to about 2k is similar. Above 2k the P version has more output in the breakup region as well as being different in the impedance especially at higher frequencies. I would think this would require some crossover changes. Also the off axis response will likely be different due to the phase plug and could impact the power response which could also require some XO changes, even if just for voicing.

Am I correct to assume that any crossover changes will have to determined by measuring equiptment and experience and not by calculations alone?
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post #18 of 18 Old 11-29-2013, 05:27 AM - Thread Starter
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I finally got in touch with Dan Neubecker. He looked over the spec differences of the two drivers and recommended no crossover change. So I'm going to move forward with it and order the parts today to take advantage of PE's Black Friday Sale! 10% off Yee-hah!
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