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Multi-Way Conventional loudspeakers with crossovers

May my problem be diffraction?
May my problem be diffraction?
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Old 9th March 2020, 06:15 PM   #11
silverprout is offline silverprout  France
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Quote:
Originally Posted by celef View Post
that could be an issue, but in my experience with dried ferrofluids makes the tweeter sensitivity drop like a stone (in a pond)
I'm not the designer of the loudspeaker unit, and i don't know if the viscosity of the fluid have a effect on the dome damping, but i can imagine that some dust agglomerated with dryed fluid residues can touch the coil, perhaps.
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Last edited by silverprout; 9th March 2020 at 06:20 PM.
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Old 9th March 2020, 07:17 PM   #12
schiirrn is offline schiirrn  Germany
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Quote:
Originally Posted by system7 View Post
What he is telling us is the speaker cabinet is no different from the room. Pure genius, IMO. You might line the inside of your cabinet with damping. Steen says you might as well line your room or the outside of the cabinet!

How good is that?

Sometimes I'm a bit slow. You're being sarcastic/ironic, right?
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Old 9th March 2020, 10:08 PM   #13
andreaemme is offline andreaemme  Italy
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All I'd want to understand is if this situation:

03_D2905_baffle_100cm.png

of my SS D2905-9500 on a baffle 16.5 cm large and 27.0 cm tall in asymmetric position and mic at 100 cm has to be considered 'normal' or really there's something of strongly wrong in something that I can't understand (I don't think it can be missing ferrofluid because the near-field response is quite good).

Let's try to see problem by another point of view. Supposing I won't be able to fight completely harshness and sybilance for a baffle problem or other, what makes a tweeter sound in the opposite manner than harshness, that is 'sweetly' and 'warmly'? What's the cross topology that gives tweeter more those footprints than others, if it can be possible to say so?

For a tweeter exists many different approaches, and I'd want to understand if their difference is due only and just to match with lower conterminous driver or is due also to give a certain character to sound output.
I've seen, for example, that major differences stay often in the 'position' of attenuation series resistor, some use it before the entire filter, some after just near driver; another thing I think related to this is the Q of the main cell, some use a Q near to theoretical, some use a more resonant Q united with a resistor of the 'before filter' type.

For example, Dennis Murphy in New Vifa Tower for the same SS D2905-9500 uses a 8 uF cap, a 0.3 mH inductor and a 3 ohm series resistor 'after' filter:

NVT.PNG

NVT_response.PNG
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Another big project-maker as Zaph Audio in his ZA-SR71 project uses for the Vifa 27TDFC (moreover very very similar to SS D2905-9500 for its specs and response) a totally different approach, a strongly resonant cell with a big 12 uF cap and a little 0.15 mH inductor, and a 4 ohm series resistor 'before':

SR71-crossover.gif

Zaph response.PNG
Why a similar solution, what's the effects on timber?

Zaph response_.PNG
(this is what it would be if resistor was put 'after')
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What of these two solutions' output timber is 'warmer' and 'sweeter', more safe from harshness?
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Old 10th March 2020, 04:36 AM   #14
YSDR is offline YSDR  Hungary
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You really making the graph overlays with Microsoft paint or similar software? There is a graph overlay option in ARTA.

People put resistors in the circuit where they get the response (frequency and impedance either) they want.

Anyway, a harmonic distortion, waterfall (cumulative spectral decay) and off-axis response may would be helpful to see.
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Old 10th March 2020, 07:29 AM   #15
ScottG is offline ScottG  United States
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Quote:
Originally Posted by andreaemme View Post

SS on baffle:
Attachment 823431

..and there is the problem right there - I can see it plainly. (..and it will get worse with an increase in spl.)

The lack of baffle round-over is also a bit of a problem.

Anyone else?
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Last edited by ScottG; 10th March 2020 at 07:32 AM.
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Old 10th March 2020, 08:11 AM   #16
RobWells is offline RobWells  United Kingdom
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Tweeter face plate looks recessed, not flush. Screws could do with being recessed and having some sort of putty smoothed over. Tweeter almost the same distance from 3 edges. (distances seem to match wavelengths of 5k to 8k)

Maybe try a layer of felt with a cutout for the dome. I think I remember an interesting 'star' shaped cutout to smooth the transition (Planet10 maybe?)

Rob.

Last edited by RobWells; 10th March 2020 at 08:23 AM.
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Old 10th March 2020, 08:34 AM   #17
vacuphile is online now vacuphile  Netherlands
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May my problem be diffraction?
It looks like a diffraction artifact. The wavelength it happens is around 8,5 cm. It may not be a coincidence that you find that same dimension in your loudspeaker (it is half the width of your tweeter enclosure).

Actually, I think the result with the bare tweeter is slightly worse. The dip in the enclosure is deeper, but higher Q (narrower) than that with the tweeter outside the enclosure. High Q peaks and dips are less audible than low Q peaks and dips.

One way to be sure is to take a couple of books of about the same size of your enclosure and use them to broaden it. If you see your dip moving to the left, you found your culprit.
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Old 10th March 2020, 10:50 AM   #18
AllenB is offline AllenB  Australia
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May my problem be diffraction?
Quote:
in baffle-less configuration
This is not how you do it. If you want to remove the baffle you'll want to use a large baffle.
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Old 10th March 2020, 09:54 PM   #19
andreaemme is offline andreaemme  Italy
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Well, thank you very much for your precious suggestions.

Quote:
Originally Posted by AllenB View Post
This is not how you do it. If you want to remove, the baffle you'll want to use a large baffle.
Of course, 'baffle-less' was to be intended 'without' any baffle around. I've been curious about this topology when listened at an audio exposition this simple two way usign a Seas ER18RNX and a Scanspeak D2608-913000 sounding incredibly well..
IMG_20160227_151341_.jpg

And what about high-pass filter topology using high Q cell with a resistor before to tame peak? What's the reason why some filters designer uses this kind of circuitry?
Since I've been convinced to be able to design crossover just with builder's measurements and a good simulator, I've got only strong disappointments. Crossover design is a difficult matter, is enough to see three totally different circuitry obtaining the same 'apparent' response curve:

Zaph's approach matching a SEAS ER18RNX:
Zaph.PNG

Another approach:
non Zaph.PNG

Still another approach:
other.PNG

How is it possible to have the same curve from circuitries with so different values? It's obvious that these system will have strong sonic differences, but from simulation it's impossible to see it before building. How is it possible, if so, to approximately forecast the sonic result from a simulation?

In the end, Michael Chua's Starling approach ever matching the same ER18RNX of the first simulation:
Starling.PNG
On the contrary, even a different curve with another very good sounding solution.

In conclusion, crossover's project equation will never have solution for a beginner like me. Let's add diffraction problems and I'll be able definitively to launch everything out from window..What a sin!

Still hope somebody will reveal magician behind good sounding crossovers.
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Old 10th March 2020, 10:01 PM   #20
ScottG is offline ScottG  United States
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Quote:
Originally Posted by RobWells View Post

Tweeter face plate looks recessed, not flush. Screws could do with being recessed and having some sort of putty smoothed over. Tweeter almost the same distance from 3 edges. (distances seem to match wavelengths of 5k to 8k)

Maybe try a layer of felt with a cutout for the dome. I think I remember an interesting 'star' shaped cutout to smooth the transition (Planet10 maybe?)

Rob.

BINGO!

It's actually better to use soft silicone caulk to push the tweeters into a flat position (relative to the baffle) and "fill" the area around the transition between face-plate and baffle. Basically you just caulk the inside "ring" of the baffle and face-plate connection area for the tweeter and slide it into place. This not only gets rid of the problem, but also lowers vibration from the baffle surface to the tweeter.

The vertical baffle-edge-to-tweeter-face-plate isn't great either with such an abrupt transition.
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Last edited by ScottG; 10th March 2020 at 10:06 PM.
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