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Multi-Way Conventional loudspeakers with crossovers

Will this horn work in a 2-way Synergy?
Will this horn work in a 2-way Synergy?
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Old 12th January 2019, 05:33 AM   #1
StabMe is offline StabMe
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Default Will this horn work in a 2-way Synergy?

Hey!

This is my first attempt at building Synergy horn. And first attempt at modelling it as well

Initially, i was going to replicate the xBush build. but couldn't find the parts the guys used in the build including the horn. So i decided to find the one with similar specs.

P-audio PH-642 seems like a good candidate. It will fit into a box the size of which i am going to tolerate and is of similar dimensions to 18 Sounds or Faital horn from the original design:

Click the image to open in full size.

I decided to go with pro drivers in this design. Mids are Beyma 8G40 and for the widebander i am going to use Faital 3FE25. For some reason, the acoustic response in Hornresp shows a rather steep high frequency roll off:

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Am i doing something wrong? Or is this a clear indication that this horn is not good for this kind of setup?

I then toyed with the Synergy Calc Excel spreadsheet, generated parameters for Hornresp for the horn of similar size/length and it produced similar results.
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Old 12th January 2019, 06:34 AM   #2
cowanaudio is offline cowanaudio  Australia
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Will this horn work in a 2-way Synergy?
I've tried at length to get decent response from small full range drivers in a 2" throat horn with no luck. Your response will likely be more extended than modelled but will have large response aberrations that change with angle, making them impossible to eq out.
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Old 12th January 2019, 07:00 AM   #3
David McBean is offline David McBean  Australia
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Quote:
Originally Posted by StabMe View Post
For some reason, the acoustic response in Hornresp shows a rather steep high frequency roll off
That's because you are looking at the Nd record power response, not the pressure response. To get some idea of the pressure response for the Nd record in isolation, delete the second segment and change the segment 1 inputs to S1 = 20.00, S2 = 495.75 and L12 (Con) = 19.00. The attachment shows the resulting on-axis pressure response (dark trace) compared to the power response (light trace).

When looking at the performance of the complete 2-way Synergy system using the Multiple Entry Horn Wizard, only the power response is shown because multiple segments are used, and the Hornresp directivity tools are not applicable in this case.
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Old 12th January 2019, 07:23 AM   #4
StabMe is offline StabMe
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Hm. Interesting.

If the response your attachment remotely mirrors what i am going to get, than this is not really that ice looking Maybe i should use a CD instead.

How did you derive S2 = 495.75 and L12 (Con) = 19.00? Is it an average approximation to get two segment horn data?

Tried modelling MEH with the wizzard. This is what i get.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Still doesn't quite resemble your graph.
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Old 12th January 2019, 07:26 AM   #5
StabMe is offline StabMe
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Hm.... Interesting.

Still doesn't look like a decent response. A lot of HF are lost. Maybe i should use a CD that goes to 500-600Hz instead.

How did you derive S1 = 20.00, S2 = 495.75 and L12 (Con) = 19.00?
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Old 12th January 2019, 08:09 AM   #6
David McBean is offline David McBean  Australia
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Quote:
Originally Posted by StabMe View Post
A lot of HF are lost.
As indicated in my previous post, the MEH Wizard only shows the power response, which is why the HF seems to fall away.

Quote:
Originally Posted by StabMe View Post
How did you derive S1 = 20.00, S2 = 495.75 and L12 (Con) = 19.00?
I used the Horn Segment Wizard to extend the conical segment to the full 19 cm length of the original two-segment horn system, while retaining the original conical horn flare tangent angle of 27.85 degrees - see attachment. The two segments were replaced with one segment so that the Directivity tool could be used to give some idea of the HF performance that could be expected to be seen in practice.
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Old 12th January 2019, 08:42 AM   #7
chris661 is online now chris661  United Kingdom
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Quote:
Originally Posted by David McBean View Post
As indicated in my previous post, the MEH Wizard only shows the power response, which is why the HF seems to fall away.
A little more clarification here:
The power response is the output of the speaker taken over a full sphere. ie, the total power that the speaker is radiating into the environment.
Since horns introduce some directivity (usually moreso above 1kHz), we need to check what's happening in front of the horn to see what we're really going to get in the kHz range.

Chris
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Old 12th January 2019, 09:31 AM   #8
StabMe is offline StabMe
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This is how AkAbak models the script exported from HornResp:

Click the image to open in full size.

Does it look more like what i am going to hear in the real life?
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Old 12th January 2019, 07:14 PM   #9
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by cowanaudio View Post
I've tried at length to get decent response from small full range drivers in a 2" throat horn with no luck. Your response will likely be more extended than modelled but will have large response aberrations that change with angle, making them impossible to eq out.
I found out the hard way that most don't work. (I bought a LOT of different ones.)

Click the image to open in full size.

The SB Acoustics 2.5" is special. The dustcap is a soft dome, and the glue is designed so that the dustcap 'decouples' from the cone at high frequency.

Click the image to open in full size.

You can see this in the measurements. At 20khz, the SB65 is 10dB louder than at 10khz! Basically you have a fixed amount of motor force operating on a lower mass (because it decoupled) so you get this rise in the response at high frequency. To improve things even further, the SB65 has a shorting ring to lower inductance.

Click the image to open in full size.

Click the image to open in full size.

The Faital isn't terrible by any means, but the high frequencies are nowhere near as nice as the SB Acoustics. The Faital has a conventional paper cone, it has no shorting ring, there's nothing special about the cone's construction. Comparing the Faital to the SB65 is like comparing a paper cone tweeter from the 70s to a modern soft dome tweeter.

Click the image to open in full size.
On paper, about the only thing that give the SB65 a run for it's money is the AudioFrog GB25. I'd love to try these out but I'm too cheap.

Last edited by Patrick Bateman; 12th January 2019 at 07:18 PM.
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Old 12th January 2019, 11:08 PM   #10
StabMe is offline StabMe
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SB65 isn't near as sensitive as 3FE22/25 to couple with two pro woofers in my design (Beyma 8G40).

I was considering this Peerless driver, but its sensitivity is low as well.

Maybe, after a bit of experimentation, i will decide to use SB65 and compromise sensitivity or will go with a CD that must be crossed at about 600Hz. Been contemplating on buying a pair of P.Audio BM-D740. The response curve on the graph looks kinda good:

Click the image to open in full size.

But will probabaly start with Faital
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