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Multi-Way Conventional loudspeakers with crossovers

100Hz two-way synergy project
100Hz two-way synergy project
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Old 21st July 2019, 04:39 PM   #1
mark100 is offline mark100  United States
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Default 100Hz two-way synergy project

Gonna use two 12"s and a bms 4594he CD. So technically not a two-way due to the coax CD, but two-way still seems to be the the best description. Plans are to crossover between 12"s and the CD at 500Hz.

Syn will cross to a sub at 100Hz. That's the crossover point I've been using for all my multiway projects, and with recent straight and CBT line array projects.
I can't see trying to take the synergy lower than 100Hz, because to get a synergy down to 30Hz with authority gets ridiculous in size and weight. So since a sub is needed, I can't see the point in trying to reach much lower than 100Hz.

Going with 60Hx40V. First prototype shown below was set for pattern control at 420Hz.
I plan the final build to control to 290-300Hz, but i wanted to try my hand on a smaller one first, to try to get the learning screwups over while the material costs are smaller. Used BWaslo's excellent spreadsheet...bless you Mr. Waslo...I couldn't be at this point without you.

The measurements are the BMS CD sections at about 1m OA for any interested. Looks like 500Hz should work fine.
I wanted to measure the CD in the horn without the 12" ports to see how response changes when the ports are added.

Speaking of ports...I've been trying out different size holes, with different locations relative to the 12"cones, and with different thickness horn walls/ thicknesses.
I don't mean ports in the horn itself...I mean ports as they pass sound from the drivers mounted in a simple small box....before placed in the horn.
Also tried a bunch of different phase plugs to reduce volume under the driver, and raise freq response.
1/16th steel works best as far as port thickness (just like patent says) but not that dang much better than 1/4" wood...(which i was happy to see.)
Ports liked to be more towards a center axis, which increases distance to apex, but again not that much better than moving them towards driver end for needed tighter spacing.

Anyway, psyched to be back building again...thx for looking
Attached Images
File Type: jpg syn 1.jpg (79.6 KB, 674 views)
File Type: jpg port loc.jpg (168.0 KB, 675 views)
File Type: jpg syn 1 raw hf and vhf OA.JPG (142.5 KB, 676 views)
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Old 22nd July 2019, 07:52 AM   #2
Thijs666 is offline Thijs666  Netherlands
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Very interesting! Is that the Peter Morris design in the first photo? I would be very interested to see how it compares to your Synergy design!

With the CD going down to 500 Hz, I don't think you'll need to do much effort to get the woofers playing high enough. In my project I got them up to about 800 Hz...
Synergy horn for 135 dB+.

I will closely follow your build!

Cheers
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Old 22nd July 2019, 01:46 PM   #3
mark100 is offline mark100  United States
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Thanks so much for linking your project, I had not seen it yet.
Just read the full thread.
Awesome build(s) ! Great discussions.
And your picts really help. The biggest unknowns for me, are figuring out the final box and access plates. Well that, and figuring out the dixie cup extender...bless you and Art of course, for making that clearer..

Yes, the box next to my synergy start is the Peter Morris 90 degree version. It also converts to the 60 degree version. Wonderful design Peter shared. But I must admit, I'm really hoping the synergy effort makes even better sound. A couple of PM90 measurements are below..the box sounds super and gets damn loud

I see you put your 12"s on the narrow angle panels. Right now, I was planning on the wide angle panels, but I've been reconsidering. Logistically, handling wise, and final box construction wise, is there reason to favor one over the other?
Attached Images
File Type: jpg PM90 mag and phase.jpg (81.8 KB, 599 views)
File Type: jpg PM90 impulse.jpg (51.5 KB, 589 views)
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Old 22nd July 2019, 04:54 PM   #4
weltersys is offline weltersys  United States
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Quote:
Originally Posted by mark100 View Post
I see you put your 12"s on the narrow angle panels. Right now, I was planning on the wide angle panels, but I've been reconsidering. Logistically, handling wise, and final box construction wise, is there reason to favor one over the other?
Mark,

On the SynTripP, the inclusion of the adjustable angle pole mount would not have been possible if the speakers were not located L/R on the narrow angle panels. With your larger cabinet, that issue may not be a consideration.
Although cone gravity displacement on a 12" won't be much of an issue, my preference would still favor placing the cones upright in the orientation the cabinet is typically used.

Good luck in your sonic pursuits!

Art
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Old 23rd July 2019, 10:50 AM   #5
Thijs666 is offline Thijs666  Netherlands
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Quote:
Originally Posted by mark100 View Post
Thanks so much for linking your project, I had not seen it yet.
Just read the full thread.
Awesome build(s) ! Great discussions.
And your picts really help. The biggest unknowns for me, are figuring out the final box and access plates. Well that, and figuring out the dixie cup extender...bless you and Art of course, for making that clearer.

Yes, the box next to my synergy start is the Peter Morris 90 degree version. It also converts to the 60 degree version. Wonderful design Peter shared. But I must admit, I'm really hoping the synergy effort makes even better sound. A couple of PM90 measurements are below..the box sounds super and gets damn loud

I see you put your 12"s on the narrow angle panels. Right now, I was planning on the wide angle panels, but I've been reconsidering. Logistically, handling wise, and final box construction wise, is there reason to favor one over the other?
The dixie cup is just to make the box smaller and the horn larger. And it works! Saves a lot of weight and space.

I'm sure that 4594 sounds awesome! It'll do well in a synergy. I must admit that in my synergies the bottom end is a bit 'problematic'. The sensitivity is a bit low compared to the rest of the frequency spectrum. It drops off quickly below ~150 Hz without the hornloading. I've tried to improve it trying different bass reflex tunings, but that only goes so far...

Those measurement curves of your Peter Norris box are really something (even if it is with EQ, it is, right!?).

My reason for putting the twelves on the sides are mostly because of the space they would need, which would make the box quite a bit bigger. And this inner volume isn't really needed if you want to tune the bass reflex ports high. In fact, I had to fill up a lot of space to make the volume even smaller. Polyurethane foam did the trick . But all Art's comments also make a lot of sense.
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Old 23rd July 2019, 02:09 PM   #6
mark100 is offline mark100  United States
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Quote:
Originally Posted by weltersys View Post
Mark,

On the SynTripP, the inclusion of the adjustable angle pole mount would not have been possible if the speakers were not located L/R on the narrow angle panels. With your larger cabinet, that issue may not be a consideration.
Although cone gravity displacement on a 12" won't be much of an issue, my preference would still favor placing the cones upright in the orientation the cabinet is typically used.

Good luck in your sonic pursuits!

Art
Art, this horizontal vs vertical mounting stuff makes me reminiscence to the PPSL sub discussion

And yep, it only makes sense that drivers in upright orientation has to be the default preference.....

I think after I mess up this prototype, I will go to side mounted...if for no other reason than replacing vertical side panel port attempts on a 60x40, will spit out a lot less wood destined for the scrap pile ! (than replacing long horiz panels)

Thx for well wishes re sonic pursuits
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Old 23rd July 2019, 03:16 PM   #7
mark100 is offline mark100  United States
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Originally Posted by Thijs666 View Post
The dixie cup is just to make the box smaller and the horn larger. And it works! Saves a lot of weight and space.

I'm sure that 4594 sounds awesome! It'll do well in a synergy. I must admit that in my synergies the bottom end is a bit 'problematic'. The sensitivity is a bit low compared to the rest of the frequency spectrum. It drops off quickly below ~150 Hz without the hornloading. I've tried to improve it trying different bass reflex tunings, but that only goes so far...

Those measurement curves of your Peter Norris box are really something (even if it is with EQ, it is, right!?).

My reason for putting the twelves on the sides are mostly because of the space they would need, which would make the box quite a bit bigger. And this inner volume isn't really needed if you want to tune the bass reflex ports high. In fact, I had to fill up a lot of space to make the volume even smaller. Polyurethane foam did the trick . But all Art's comments also make a lot of sense.
Yep, the dixie cup idea rocks, especially for portability / PA.
I'm toying with the idea of making it out of thick foam board...

The PM90 measurements we definitely EQed, and used linear phase crossovers. I stuck 'rephase' on their comment field to help folks gather linear phase was involved.

Interesting to hear the bottom end of your synergies is a little problematic...
I've been studying posts on port placement (which mostly talk about mids), and have been trying to incorporate comments about port location needing an appropriate flare rate to reach down low in frequency.
In Hornresp I keep getting that a port location within 1/4WL of a 500Hz crossover, has a pretty high flare cutoff freq.

Sometimes I get the impression that mids used in synergies are as much for the purpose of being able to move the low ports further out the horn, as they are for bridging to the CD...

On thing is for sure ...Gotta get better with hornresp
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Old 25th July 2019, 10:41 AM   #8
Thijs666 is offline Thijs666  Netherlands
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Quote:
Originally Posted by mark100 View Post
Sometimes I get the impression that mids used in synergies are as much for the purpose of being able to move the low ports further out the horn, as they are for bridging to the CD...
Hmm, that might very well be. But why then doesn't Art's SynTripP have mids? Why does his design get away with it?

I have experimented with bigger ports, letting them run further down the mouth, but that didn't seem to help much. Made things worse for the CD response if anything...
The most important thing was getting the ports as close to the CD entry as possible in order to get them to play high enough, but with 500 Hz as a crossover point, that seems a little less important.
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Old 25th July 2019, 04:16 PM   #9
mark100 is offline mark100  United States
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Yeah, I hear you re Art's SyntripP working without mids....
I'm guessing Art's box gets the low end it does due to very well designed BR ports..??
I've been studying your design and Art's quite a bit as I try to make sense of how ports work vs measurements. I've tried a lot of different sizes, shapes (circle vs ribbon vs teardrop), locations (corner vs center), distance from throat, etc.

The only thing I know for certain yet, is that how tight I screw the horn back together makes the biggest difference of anything I try

One big puzzler is that frequency response doesn't really go up as I minimize port to throat distance. I've been getting response to 500Hz almost independent of port location (or size)...from 2.5" to 6.5" (center of ports to throat).
Initial quick attempts at volume reduction under cone have shown more of an effect at raising freq response than port location.

I've pretty much used up the first prototype's ability to handle any more port experiments. Between thin sheet steel used as a port closing guillotine, and foam pugs and duct tape, she's about had it. Off to the junk pile !

Gonna build a 2nd proto now, exact same size 60x40, and will move drivers to the vertical panels (so a 40x60 in BWaslo's calculator, ableit with an 851Hz control freq)
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Old 25th July 2019, 04:26 PM   #10
xrk971 is online now xrk971  United States
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100Hz two-way synergy project
Nice project! I also designed for 100Hz bottom end on the Trynergy. Makes great sense with all the low cost HT subs available to handle that.

Presenting the Trynergy - a full range tractrix synergy.
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