|
Home | Forums | Rules | Articles | diyAudio Store | Blogs | Gallery | Wiki | Register | Donations | FAQ | Calendar | Mark Forums Read |
Multi-Way Conventional loudspeakers with crossovers |
|
Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving |
![]() |
|
Thread Tools |
![]() |
#31 |
diyAudio Member
Join Date: Jun 2003
Location: Chamblee, Ga.
|
![]() ![]()
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents. |
![]() |
![]() |
#32 |
diyAudio Member
Join Date: Jun 2003
Location: Chamblee, Ga.
|
Good to know, thanks!
GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents. |
![]() |
![]() |
#33 |
diyAudio Member
Join Date: Oct 2006
Location: San Diego
|
Mazama Unity Horn Thanksgiving 2020 - YouTube
Here's a video of Mazama 2.0 playing. On YouTube it doesn't sound particularly great, I hear a lot of mp3 compression artifacts and doppler distortion. But you get a general idea about how it sounds. |
![]() |
![]() |
#34 |
diyAudio Member
Join Date: Oct 2006
Location: San Diego
|
I'll probably sell a few of these, if I can get it to work.
In the event of that, if you're buying one, you'll need to pay attention to this post to build the speaker. ![]() ![]() ![]() ![]() Mazama 2.0 uses an HDF mounting plate for the MCM midranges. The mounting plate measures 5.25" / 13.3cm in diameter. The midrange tap is drilled right through the center of the mounting plate. The midrange tap is 1.125" / 2.9cm in diameter. In order to glue the mounting plates to the waveguide, I used "Loctite Tite Foam." The mounting plates are basically mounted so that the midrange tap is right at the edge of the waveguide. If you look at the pics you can get the general idea of where it's mounted. Obviously, the midbasses are not mounted on the center of the horn. This is by design, to improve the polar response. ![]() ![]() ![]() ![]() Here's some more pics that show how the midbasses are mounted. |
![]() |
![]() |
#35 |
Overly Enthusiastic
diyAudio Member
|
what is the model number for the mcm midrange?
It could perhaps be pushed higher with a small sealed rear chamber and an asymmetric tap closer to the throat? (although this would make low frequency operation impossible) The N151M tweeter is great but it looks like it should be crossed at 1.8kHz due to the strongly rising distortion below that. I get that its not an issue at low levels but I worry about it quickly becoming an issue for me
__________________
CHR-70+Subs (2011?). ART CLEANBox Pro Low freq modification. 3 way, MEH, PA tops. Isobaric reflex 30Hz subs. Quiet PA AMPS? |
![]() |
![]() |
#36 |
diyAudio Member
Join Date: Oct 2006
Location: San Diego
|
![]() Here's the frequency response and distortion measurement. Pretty good I think. The compression driver has lower distortion than the midrange array, but what do you expect from $13 woofers? https://www.newark.com/mcm-audio-sel...one/dp/39C2182 ![]() Here's the phase response. I can improve on this, but I intentionally refused to use DSP delay here. I can flatten out the phase by manipulating the crossover slope or by adding delay. Having said that, this phase response is still pretty good I think. There's about 180 degrees of phase shift at the crossover point. I can improve on that by tweaking the crossover slopes, or adding DSP delay if necessary. Right now, the crossover slopes on the tweeter and the midbass are symmetrical, and due to that, there's some delay between the tweeter and the midbass. (Because the midbass is about three inches ahead of the tweeter.) ![]() Here's the polar response. This is pretty darned good I think. I've been building speakers for over 20 years and this polar response is Top Ten I think, among my designs. Keep in mind, these measurements are very early. The speaker is mounted on a cardboard baffle and I invested a grand total of about 30 minutes tweaking the crossover. IE, these results will improve. |
![]() |
![]() |
#37 |
diyAudio Member
Join Date: Oct 2006
Location: San Diego
|
To me, the Gold Standard is generally Genelec. From the measurements published at audiosciencereview and Princeton.edu, their directivity is about as good as it gets.
![]() Here's my speaker And attached are the polars of the $6000 Genelec 8351A The parts cost on my speaker is about $500 per pair. |
![]() |
![]() |
#38 | |
diyAudio Member
Join Date: Jan 2004
Location: Toronto, ON, Canada
|
Quote:
|
|
![]() |
![]() |
#39 |
diyAudio Member
Join Date: Nov 2012
|
These results look really good. I look forward to seeing some crossover optimization if you don't end up throwing these away.
![]() So is the 2 * FS / QES idea for a synergy midrange driver out the window? This MCM's 2 * FS / QES, if it's listed specs are to be believed, is 215hz? Yet this configuration works up to 1500hz? Is the 'Suitable midrange cone, for bandpass mid in Unity horn' thread just outdated or should it be deleted? How does one REALLY select a suitable midrange cone, for bandpass mid in Unity horn? Is that a new thread? |
![]() |
![]() |
#40 | |
diyAudio Member
Join Date: Oct 2006
Location: San Diego
|
Quote:
This has honestly been the culmination of at least a dozen projects. In particular, I spent most of the holidays of 2019 making phase plugs for tweeters. That taught me a lot about how to extend the high frequency output of a driver. If you crunch the numbers on a tweeter, you'll find that it should run out of steam at about 3-4khz on a horn, based on the formula of "2 * FS / QES." Due to this, the 'trick' to getting it to play out to 20khz is: 1) Smaller is better. Way easier to get a 3/4" tweeter to play to 20khz than a 1" tweeter. 2) Pathlength is king. Even a difference of a millimeter makes a difference at 20khz. So I applied some of that here. In particular, using a single tap instead of two, in order to guarantee that the pathlengths are as close to equal as possible. If I'd 3D printed the entire thing I would've used a phase plug with slits, like a compression driver. But since this one was going to be combined with a commercial waveguide, I went with a straight hole. I think I could extend the bandwidth even higher if I put some polyfill inside of the chamber. The idea would be to acoustically attenuate the radiation from the cone, while leaving the radiation from the dustcap untouched. Basically the idea is that the sound radiated from the cone will be around two inches out of phase with the dustcap, due to the longer pathlength through the midrange tap (aka phase plug.) A difference of two inches equates to a dip at 3375Hz, because the radiated by the dustcap is 180 degrees out-of-phase with the sound radiated by the loudspeaker cone. The "PDR" versions of the Bohlender Graebner drivers work on a similar principle. The stuff felt on the edges, sacrificing maxium output to increase high frequency extension. But that last part is admittedly overkill and hopefully unnecessary here. Side note: I need another project like I need another hole in my head, but one of the original variations on this project, was to use a bunch of 3" drivers. The Fountek FE85 in particular. Two of these won't generate much output, but if you stuffed six onto the horn you could get some real output. Similar in concept to how a 3" midbass won't be HiFi, but if you cram eight or sixteen of them into an array, it can really get loud. With a carefully designed phase plug, I'll bet the FE85 could reach as high as 2khz. Last edited by Patrick Bateman; 25th November 2020 at 12:32 AM. |
|
![]() |
![]() |
Thread Tools | |
|
|
New To Site? | Need Help? |