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Multi-Way Conventional loudspeakers with crossovers

Seas L15RLY/P with Morel DMS30s in Visaton WG148R
Seas L15RLY/P with Morel DMS30s in Visaton WG148R
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Old 13th January 2018, 07:08 PM   #21
eriksquires is offline eriksquires  United States
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Hey Zvu, Very nice looking work!

What were your thoughts in general about measurements vs. intended destination?

Also, what is that 0.25uF C/ 1 Ohm R doing??


Best,

E

(Remvoed reference to BF compensation, the parts I thought were involved are not)
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Last edited by eriksquires; 13th January 2018 at 07:14 PM.
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Old 13th January 2018, 08:00 PM   #22
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by eriksquires View Post
Hey Zvu, Very nice looking work!

What were your thoughts in general about measurements vs. intended destination?
I'm afraid i don't fully understand the question, so i'll answer to the best of my understanding. My goal was to make bookshelf that has good power response, controlled directivity, good phase response, flat frequency response and pass-band free of resonances with as benign impedance as i can - and all that in a conventional packaging with passive crossover.

Visaton waveguide handles edge diffraction higher in frequency, it moves acoustic center of tweeter closer to the midwoofer, it boosts frequency response bellow 10KHz to enable lower crossover point than usual and by that makes power response better without dip at crossover frequency, it lowers distortion. Only thing i could do better than this (that i can remember at this moment) is to use coaxial driver and make vertical off-axis identical to the horizontal.

I took an ordinary metal cone driver and ordinary silk dome tweeter to achieve (what i believe is) extraordinary result. I believe that biggest mistake one could make is to buy some drivers and stop with the design when it is good enough. I've tried to make this as close to perfect as the drivers and my knowledge would let me to, regardless of number of crossover parts or similar mumbo-jumbo. The crossover needs to be as big and complex as it needs, to handle all of the problems on and off axis, in my opinion.

Now that the cone resonance, characteristic for metal cones, is under -45dB (which is domain of harmonic distortion so i would guess quite undetectable) - i think i fulfilled my goal.

Quote:
Originally Posted by eriksquires View Post
...Also, what is that 0.25uF C/ 1 Ohm R doing??
0,25uF with 1 ohm across the midwoofer coil is tank filter - or "not quite bottomless notch" at around 8KHz and serves to suppress the resonance even more than slope would do on its own.
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Last edited by Zvu; 13th January 2018 at 08:29 PM.
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Old 13th January 2018, 09:05 PM   #23
eriksquires is offline eriksquires  United States
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Hi Zvu,

Sorry I wasn't more clear, but your response was still illuminating. I was thinking more about the bass response in the bookshelves. I'm thinking about how you measured them and accounted for boundary reinforcement in the bass so that when you put them in the bookshelves they would be properly balanced.

Ty Re: 8kHz Tank.

Best,

E
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Old 13th January 2018, 09:12 PM   #24
Zvu is offline Zvu  Serbia
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Bookshelf by size not by role. Maybe i should have wrote "standmount". Their place is on the bookshelf only when my little daughter is in the room.

This is a full baffle step design with F3=45Hz and it merges with the room quite nicely. I did recommend (maybe not on this forum) that their placement shouldn't be in the corners but they don't mind being close to rear wall.

Thanks for pointing that out.

Cheers
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Last edited by Zvu; 13th January 2018 at 09:25 PM.
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Old 13th January 2018, 11:01 PM   #25
eriksquires is offline eriksquires  United States
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Ty.

That was NOT a criticism by the way! I think there is a place for stand-mounts and speakers that go onto bookshelves. The use of a waveguide, plus the picture made me (incorrectly) think you had envisioned them as on-bookshelf speakers to begin with, so I wanted to know about optimizations you might have done around that.

I did not mean to suggest the speakers lacked merit!

Best,

E
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Old 14th January 2018, 05:14 PM   #26
Mario Pankov is online now Mario Pankov  Europe
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Seas L15RLY/P with Morel DMS30s in Visaton WG148R
Quote:
Originally Posted by Zvu View Post
If i manage to find a decently priced pair - i'll report back with the results.
Why not buy some cheap aluminium cone woofer and experiment with it? I once thought about this and eyed the Dayton aluminium cone as it is cheap and has a pronounced breakup. I wanted to try the Scanspeak approach - cut slices in the cone and add polypropylene or some highly damping glue but aborted it as I am more keen on putting my cash into another experiment on creating a hard cone.
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Old 15th January 2018, 06:53 AM   #27
Zvu is offline Zvu  Serbia
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We'll see.

Whether it works or not, i definitely want another pair of L15. I really want to design MTM with it. I've read a ton of negative experiences and very few positive ones about MTM but i presume that the reason is (as often happens) poor design.

I've never listened any good implemented MTM such as Gryphon Mojo, Snell Illusion, YG Acoustics Sonja 1.3, anything from Golden Ear or similar. The ones i did listen i consider inadequate to say the least (bad implementation of lousy drivers).
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Last edited by Zvu; 15th January 2018 at 07:04 AM.
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Old 19th January 2018, 06:30 AM   #28
Mario Pankov is online now Mario Pankov  Europe
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Seas L15RLY/P with Morel DMS30s in Visaton WG148R
I think one possibility is the choice of drivers and in some cases - the design flaws. A proper MTM would require a few prerequisites to be met:

1. Very close spacing between the midwoofers which might benefit from
* use nothing bigger than 4" with tiny frames
* small flange tweeter like the SB26STCN or even better without a flange and glue it to the baffle with some low-medium strength silicone so it can be replaced if needed
* offset the tweeter so woofers can be mounted even closer (besides the diffraction benefit)
* Y-dimension curved baffle would definitely help with comb effects (many pro arrays use this approach)

or

1. The use of a waveguide and a tweeter like the SB29RDC or the Monacor DT300 - in a 17-18cm waveguide both can take a 4th order LR down to 1.5Khz which allows 5" midwoofers to be used (I did it and it works, first dip from comb was at around 1.6Khz measured at +/- 30 degrees). I`m not home but can post a pic of the finished loudspeaker later.
2. Addition of supporting woofers, 6-7", to fill the gap but this makes the MTM pretty expensive as it will feature lots of drivers and crossover work will be a challenge
3. Listen to them from 2m or farther

Besides, the steep slopes an MTM usually needs mean higher gd and more crossover nonlinearities when you compare the input to the output signal, maybe another reason why you didn`t like them. I have not heard an MTM I like a lot either (even the one I mentioned above designed and built by me )
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Old 19th January 2018, 07:50 AM   #29
Zvu is offline Zvu  Serbia
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Originally Posted by Mario Pankov View Post
(I did it and it works, first dip from comb was at around 1.6Khz measured at +/- 30 degrees). I`m not home but can post a pic of the finished loudspeaker later...
Please do. I'm always interested in that kind of stuff.

Quote:
Originally Posted by Mario Pankov View Post
...I have not heard an MTM I like a lot either (even the one I mentioned above designed and built by me )


What's the thing you didn't like ?
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Last edited by Zvu; 19th January 2018 at 07:53 AM.
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