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Multi-Way Conventional loudspeakers with crossovers

SNR-1 : Mundorf / Scanspeak 2 Way
SNR-1 : Mundorf / Scanspeak 2 Way
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Old 27th December 2017, 01:02 AM   #21
Bill poster is offline Bill poster  Thailand
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I'm guessing Troels is unhappy with what he perceived to a colouration just under the crossover point of his design, rather than the frequency response. Hence why he designed a 3 way with the 2" accuton. I think its a matter of taste, some may like the 'lush' sound of a paper cone being used in that region. I've heard similar critique about the satori 6.5" when crossed above a certain point.
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Old 27th December 2017, 08:49 AM   #22
Mario Pankov is offline Mario Pankov  Europe
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If the baffle were curved a la magico, wd that help? I'm guessing the baffle plays a role with that rise above baffle step
Download something like Edge and play with it In short - it depends. It might be a contribution of the loudspeaker driver itself or a baffle step effect. If it is the second, yes, a roundover/chamfer do the trick with the second being somewhat cheaper to implement (bits are cheaper) but for best results 2 or 3 consecutive chamfers (creating a curved like surface) are needed. Small roundovers of 1/2" or so have very little effect (but have some). At about an inch you`re floating, better if they`re 2" or bigger. Another trick is to offset the drivers but it is not as visually appealing to some as centered drivers. Third aproach which works for small drivers only is a very narrow baffle where you could push the first baffle diffraction bump and consecutive dip above the crossover frequency. I`ve never been able to do this with drivers bigger than 5" or so. Problem is, what is somewhat doable is a roundover of about 1 1/4" at most and that would require your router ot be put on a table, the bits are really big and scary when they rotate even at 10k rpm. Bigger roundovers I believe would need a slice based structure, so either a CNC router and a large amount of MDF sheets or to have a steel template cut by a CNC and then use it with a quality router and a bearing cutter (I saw the idea from a forum member on here, Wesayso, so redit to him) are the options. That means lots of cutting so router must be of good quality and you`d spend some good money on bits.

Last edited by Mario Pankov; 27th December 2017 at 08:52 AM.
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Old 27th December 2017, 09:09 AM   #23
Bill poster is offline Bill poster  Thailand
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Quote:
Originally Posted by Mario Pankov View Post
Download something like Edge and play with it In short - it depends. It might be a contribution of the loudspeaker driver itself or a baffle step effect. If it is the second, yes, a roundover/chamfer do the trick with the second being somewhat cheaper to implement (bits are cheaper) but for best results 2 or 3 consecutive chamfers (creating a curved like surface) are needed. Small roundovers of 1/2" or so have very little effect (but have some). At about an inch you`re floating, better if they`re 2" or bigger. Another trick is to offset the drivers but it is not as visually appealing to some as centered drivers. Third aproach which works for small drivers only is a very narrow baffle where you could push the first baffle diffraction bump and consecutive dip above the crossover frequency. I`ve never been able to do this with drivers bigger than 5" or so. Problem is, what is somewhat doable is a roundover of about 1 1/4" at most and that would require your router ot be put on a table, the bits are really big and scary when they rotate even at 10k rpm. Bigger roundovers I believe would need a slice based structure, so either a CNC router and a large amount of MDF sheets or to have a steel template cut by a CNC and then use it with a quality router and a bearing cutter (I saw the idea from a forum member on here, Wesayso, so redit to him) are the options. That means lots of cutting so router must be of good quality and you`d spend some good money on bits.
Cheers for all.info! The stepped baffle is such an ugly thing, but i like the way Raidho get around this, with a shallow waveguide and an ingenious angled baffle
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Old 27th December 2017, 09:12 AM   #24
andy2 is offline andy2  United States
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Cheers for all.info! The stepped baffle is such an ugly thing, but i like the way Raidho get around this, with a shallow waveguide and an ingenious angled baffle
Well Raidho has the resource to try out all sort of baffles. I don't have that much wood and time. If I use slanted baffle, I probably go with a fix 7.5 degree and see what happens.
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Old 27th December 2017, 09:16 AM   #25
Bill poster is offline Bill poster  Thailand
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Originally Posted by andy2 View Post
Well Raidho has the resource to try out all sort of baffles. I don't have that much wood and time. If I use slanted baffle, I probably go with a fix 7.5 degree and see what happens.
Sorry Andy didnt realise we were continuing a discussion.
cad it up quickly and get it cnc'd. V easy, cheap and saves lots of time.
As there was really no excuse not to, I learnt basic cad just for speaker building.
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Old 27th December 2017, 11:41 AM   #26
Mario Pankov is offline Mario Pankov  Europe
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The stepped baffle is such an ugly thing
Sorry, I might have misunderstood your question, my post concerned edge diffraction (also applicable to the physical Z-dimension offset created with an extra piece of MDF for the woofer). The problem with the latest build of TG in terms of offseting is this massive edge in close proximity to the tweeter. I have done it and it creates a substantial ripple, so went for a slanted design. Not sure why it was done this way, in the majority of his other designs it was slanted. I suspect the reason to be a desire to mount the drivers closer to each other. With a small waveguide like in the Raidho example, you will control the tweeter beam to a certain frequency, a 17cm waveguide (around 6.5") would loose control somewhere below 2Khz where the wavelength becomes too long so you will still get this diffraction. But here`s the catch - if you go for a shallow 16-20cm waveguide like the Monacor WG300 or the newer Visaton WG148 which was used with great effect in Zvu`s project somewhere on the forum, the waveguide is deep enough to provide the physical offset alone so no need for any extra work. I`m still not sure why popularity of waveguides is so low with commercial designs, they solve a lot of problems.

Last edited by Mario Pankov; 27th December 2017 at 11:45 AM.
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Old 27th December 2017, 11:52 AM   #27
Bill poster is offline Bill poster  Thailand
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I`m still not sure why popularity of waveguides is so low with commercial designs, they solve a lot of problems.
V true esp in 2 ways
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Old 27th December 2017, 01:27 PM   #28
system7 is offline system7  United Kingdom
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We had a thread a while back about merlinx76' problems with the ZRT 2.5 Zaph design. A poor and overly simplistic and low filter with a difficult 18W8531G00 driver, IMO. And I DO have the FRD and ZMA files for this driver direct from Zaph himself.

Click the image to open in full size.

Erik mercilessly trolled it with his opinion that the 4 ohm 18W4531G00 is great in an MT. It didn't help at all, because that is a very different animal from a poorly implemented 2.5 way.

Now I am having to suffer his gibes that only I and Troels Gravesen find the 18W8531G00 difficult. It actually isn't too hard if you have the right idea. But, TBH, I'm not sure Erik has the right idea at all. 6dB slope with a 4kHz notch? Really? Best you can do?
Attached Images
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File Type: png SNR-1 system7.PNG (16.9 KB, 229 views)
File Type: png Erik SNR-1 18W8531.PNG (21.4 KB, 226 views)
File Type: png system7 SNR-1 18W8531.PNG (21.3 KB, 227 views)
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Old 27th December 2017, 03:28 PM   #29
eriksquires is offline eriksquires  United States
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Steve,

I brought your name up here out of respect and completeness. I really don't feel I have mercilessly trolled you or anyone else. I have been just as stubborn about my opinion as you are of yours, and as I have pointed out, I strongly suspect there has been an undocumented engineering change as the spec sheet and the drivers I have in front of me (sounding great) simply do not match.

As for the 1st order electrical that you point out, that proves my point that this driver is easy as cake to use. If this driver was nearly as difficult as described by others who do not have the drivers in hand such a gentle slope would never have worked.

Best,

E
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Old 27th December 2017, 10:50 PM   #30
system7 is offline system7  United Kingdom
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No, you still aren't listening, Erik.

The Scan woofer might work OK on a 6dB, but actually gets much harder on 12dB or even 18dB. We are, after all, not in the business of building LGWAG speakers. We want to be able to play Mendelssohn's Elijah!

You have also missed a trick with the whole concept. This is how you do $500 ribbons with series wired 4 ohm bass for the tidy higher impedance and good dispersion:

Click the image to open in full size.

Click the image to open in full size.

Happily, I feel confident a 2.5kHz+ crossover is possible here. Impedance takes a beating, but that is what happens with ill-behaved drivers that force you to depart from optimal values. TBH, I think a Peerless 830874 or 830875 would make more sense. The poly dustcap works better than anything paper. More damping, you see.
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