Middriver selection?

buggsson · 17th January 2008, 01:46 AM

I am still struggling with what kind of a system to build. While I am trying to decide, I know as much as I will build either a sub and a two-way system on top of the sub, or a threeway system, all sealed.

When selecting mids, does the EBP-value (Fs/Qes) still have to be below 50 to be really suitable for a sealed implementation?

I will try to crossover to the tweeter at around 6 kHz, which narrows my search considerably. (I do not want to go lower than 4 kHz, minimum.)

I have the woofers more or less sorted out.

For a threeway system, can you really approach driver selection in a stepwise procedure as I am trying to? If not, can someone please lay out a proper procedure?

And what about polypropylen cones? I have stayed away from these in my subwoofer selection, are they okey as mids?

Caferacer · 17th January 2008, 03:00 PM

You can use a sealed box for pretty much any mid. As long as it goes as low as you need it to go in that sized box. Gives the best power handling too.
As for your upper end, a 4K crossover means 5.25" is about as big as you can go. 6K probably limits you to 4" without off axis problems.
Polypropelene has been used in a lot of good mids. The 5.25" Vifa's come to mind. Many poly mids have a nice rolloff at the top making them easier to cross high like you want to.

Samuli^ · 17th January 2008, 03:18 PM

6kHz wave is about 5.6cm long, so even with a 3" driver you're going to have beaming issues and vertical lobing. How much that is subjectively a problem at those frequencies I don't know, but to me crossing over at 6 kHz doesn't sound practical.

What is your reasoning choosing XO that high? Also, before suggesting
a mid, how high are the woofers good to?

planet10 · 17th January 2008, 07:29 PM

Here is a left field suggestion... i've recently been playing with the Fostex FF85K (not stock mind you) and have really been impressed. I've started thinking of this as a 3/4" tweeter which with its big surround allows XOs as low as 200-350 Hz. It opens up a whole new world of possibilities.

Its one downside is fairly low efficiency (~87 dB once i've done it up)

dave

buggsson · 17th January 2008, 09:14 PM

Well my reasons for wanting to go that high is to avoid crossing over in a region of interest, and I read it on a speaker manufactuers home page, that I trusted to know what he was talking about. I know most folks cross much lower. I guess I might have to rethink that. I see that even crossing over at 4 kHz would only allow me of using a 5.25" driver, I was planning to use primarily a pair of 7" or 8" drivers per channel. As it seems, I will have to comprimise, either in crossover frequency or driver size, or both?

I don't know where I would like to cross the woofers, it depends on the system I will decide on. Presently I am contemplating 3 different systems, and I am trying to find some suitable drivers to put into my software for simulations once I decide on system. For woofers, I have on my list from 10" to 15".

Maybe it would be wiser to first finally decide on the system and then go driver hunting?

Caferacer · 17th January 2008, 09:56 PM

There are compelling reasons for running a midrange high to keep the crossover out of our ears most sensitive region. Heck, check out the fullrange forum. Some people run a small mid "fullrange" and add just a supertweeter at like 10K. However, asking a standard 7" midwoofer to go that high is asking too much. Some are better than others, but they all get ragged and lose dispersion above say 3K.

Samuli^ · 17th January 2008, 10:04 PM

If you're undecided on the woofers, you might want to look at the SLS series from peerless. These are modestly priced, but good quality drivers with okayish xmax (+-8mm) and the 10/12" versions will go happily to 1 Khz or so with good dispersion, allowing you lots of room to use small midrange to help cross high at the tweeter. Downside is these require relatively big boxes.

tinitus · 17th January 2008, 10:27 PM

This seem to be a good 12", not too many of those around

http://www.sbacoustics.com/specprodu...%20SB34NRX75-6

Samuli^ · 18th January 2008, 12:33 AM

Looks like an excellent driver judging from the datasheet! How much does those cost and is there any distortion measurements available?

tinitus · 18th January 2008, 12:50 AM

http://www.madisound.com/catalog/pro...oducts_id=8304

Madisound says 141USD, but sold out...I dont know how and why as they have not been on the market yet...funny that Madisound are the first to announce a "danish" driver, before its even available

Being in EU it might be worth a try to contact SBA directly

17th January 2008, 01:46 AM	#1
buggsson diyAudio Member Join Date: Sep 2005	Middriver selection? I am still struggling with what kind of a system to build. While I am trying to decide, I know as much as I will build either a sub and a two-way system on top of the sub, or a threeway system, all sealed. When selecting mids, does the EBP-value (Fs/Qes) still have to be below 50 to be really suitable for a sealed implementation? I will try to crossover to the tweeter at around 6 kHz, which narrows my search considerably. (I do not want to go lower than 4 kHz, minimum.) I have the woofers more or less sorted out. For a threeway system, can you really approach driver selection in a stepwise procedure as I am trying to? If not, can someone please lay out a proper procedure? And what about polypropylen cones? I have stayed away from these in my subwoofer selection, are they okey as mids?

17th January 2008, 07:29 PM	#4
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	Here is a left field suggestion... i've recently been playing with the Fostex FF85K (not stock mind you) and have really been impressed. I've started thinking of this as a 3/4" tweeter which with its big surround allows XOs as low as 200-350 Hz. It opens up a whole new world of possibilities. Its one downside is fairly low efficiency (~87 dB once i've done it up) dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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17th January 2008, 03:00 PM	#2
Caferacer diyAudio Member Join Date: Apr 2007	You can use a sealed box for pretty much any mid. As long as it goes as low as you need it to go in that sized box. Gives the best power handling too. As for your upper end, a 4K crossover means 5.25" is about as big as you can go. 6K probably limits you to 4" without off axis problems. Polypropelene has been used in a lot of good mids. The 5.25" Vifa's come to mind. Many poly mids have a nice rolloff at the top making them easier to cross high like you want to.

17th January 2008, 03:18 PM	#3
Samuli^ diyAudio Member Join Date: Sep 2005	6kHz wave is about 5.6cm long, so even with a 3" driver you're going to have beaming issues and vertical lobing. How much that is subjectively a problem at those frequencies I don't know, but to me crossing over at 6 kHz doesn't sound practical. What is your reasoning choosing XO that high? Also, before suggesting a mid, how high are the woofers good to?

17th January 2008, 09:14 PM	#5
buggsson diyAudio Member Join Date: Sep 2005	Well my reasons for wanting to go that high is to avoid crossing over in a region of interest, and I read it on a speaker manufactuers home page, that I trusted to know what he was talking about. I know most folks cross much lower. I guess I might have to rethink that. I see that even crossing over at 4 kHz would only allow me of using a 5.25" driver, I was planning to use primarily a pair of 7" or 8" drivers per channel. As it seems, I will have to comprimise, either in crossover frequency or driver size, or both? I don't know where I would like to cross the woofers, it depends on the system I will decide on. Presently I am contemplating 3 different systems, and I am trying to find some suitable drivers to put into my software for simulations once I decide on system. For woofers, I have on my list from 10" to 15". Maybe it would be wiser to first finally decide on the system and then go driver hunting?

17th January 2008, 09:56 PM	#6
Caferacer diyAudio Member Join Date: Apr 2007	There are compelling reasons for running a midrange high to keep the crossover out of our ears most sensitive region. Heck, check out the fullrange forum. Some people run a small mid "fullrange" and add just a supertweeter at like 10K. However, asking a standard 7" midwoofer to go that high is asking too much. Some are better than others, but they all get ragged and lose dispersion above say 3K.

17th January 2008, 10:04 PM	#7
Samuli^ diyAudio Member Join Date: Sep 2005	If you're undecided on the woofers, you might want to look at the SLS series from peerless. These are modestly priced, but good quality drivers with okayish xmax (+-8mm) and the 10/12" versions will go happily to 1 Khz or so with good dispersion, allowing you lots of room to use small midrange to help cross high at the tweeter. Downside is these require relatively big boxes.

17th January 2008, 10:27 PM	#8
tinitus diyAudio Moderator Join Date: Nov 2005	This seem to be a good 12", not too many of those around http://www.sbacoustics.com/specprodu...%20SB34NRX75-6

18th January 2008, 12:33 AM	#9
Samuli^ diyAudio Member Join Date: Sep 2005	Looks like an excellent driver judging from the datasheet! How much does those cost and is there any distortion measurements available?

18th January 2008, 12:50 AM	#10
tinitus diyAudio Moderator Join Date: Nov 2005	http://www.madisound.com/catalog/pro...oducts_id=8304 Madisound says 141USD, but sold out...I dont know how and why as they have not been on the market yet...funny that Madisound are the first to announce a "danish" driver, before its even available Being in EU it might be worth a try to contact SBA directly

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