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Old 31st January 2005, 04:54 PM   #11
AndrewT is offline AndrewT  Scotland
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Hi,
re post 10; how did you manage to achieve that smooth response from Hornresponse? When I change from infinite horn to 0.5PI my response changes to very lumpy. I have tried a variety but it is always bad!
Give us the secret - PLEASE.
regards Andrew T.
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Old 1st February 2005, 07:31 AM   #12
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Quote:
Originally posted by AndrewT
Hi,
re post 10; how did you manage to achieve that smooth response from Hornresponse? When I change from infinite horn to 0.5PI my response changes to very lumpy. I have tried a variety but it is always bad!
Give us the secret - PLEASE.
regards Andrew T.
See the horn response screen shot I made (link given in an earlier thread) and see all parameters, I optimised it using PD184 speaker and my room limitations. Then I discoverd that in a 0.5Pi space a large back volume helps low frequencies.
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Old 1st February 2005, 08:37 AM   #13
AndrewT is offline AndrewT  Scotland
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Hi cordraconis,
tell us how you got Samehorn to look so good (parameters?)
regards andrew T.
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Old 1st February 2005, 10:56 AM   #14
lltnt is offline lltnt  China
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Biiiiiiiig one!!
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Old 1st February 2005, 03:36 PM   #15
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Quote:
Originally posted by AndrewT
Hi cordraconis,
tell us how you got Samehorn to look so good (parameters?)
regards andrew T.
Ok, here are my settings, but with the screenshot vincent mentioned and changing the back volume you could have found it yourself.

http://users.telenet.be/Hellhouse/SameHorn-sett.JPG

I've been reading this: http://www.audioasylum.com/forums/hu...ges/49577.html
for the last days, to try to figure out why my calculated throat area is so small. So far I still haven't found a clue about any errors in the Leach' formula, but I'm still reading ...
I tought I mention this link, just in case it should be of interest for anyone.

As for your horn Vincent, I've taken the settings from the link above, and put a front chamber in it. Leach' says the front chamber can extend the high-frequency responce by matching the air resistance for that upper freqency, to the rest of the system. (Critically damp it.) I've tried a few quick numbers and i came up with this:
VTC is 13500, and ATC is 1300.

The SPL curve shows the upper freq are less, thus acting as a low-pass filter, and the -3dB point is indeed around 300Hz.
As expected, you gain a more even and more efficient (well, ... more sensitive that is) responce between the 2 chosen freq of 38-300Hz.
Please keep in mind that this is only a quick try from me. I haven't tried to actually calculate optimum front chamber volume yet.

There are two questions I have for you:
- Can you still remove the back volumes you have made? I think I've seen you made them out of brick walls.
- Would you like to try (maybe only one of your horns, for comparison ) to make a temporal back-and-front chamber to check my sim? Maybe you can hear the few dB more efficiency from the prediciton.

in your last post you said a larger back chamber extended LF responce. Have you tried to not use a back chamber at all? That room you have should be a LOT bigger than the 99999 liters max you can input in hornresp ... (aldough the sim says the SPLcurve is less flat. Maybe Skramstadt - sorry for typo - knows more.)

@AndrewT:
At my very first try in hornresp, I used a very large backchamber and some arbitrary numbers for the front chamber, as I didn't have a clue about what the different settings did. I ended up with a very small throat area which I essentially used as a lowpass-filter to even responce.
The SPLcurve was rather flat from 20-500hz, but it had a lot of riples every 10Hz or so. (+3dB and -3dB, so 6dB variance in total)
Maybe you have the same problem? Try to make the compression ratio (cone area/throat area) no more than 3, else the driver won't be able to compress the air enough in the throat. (no more piston movement and lots of non-linearities).
Double click on the mouth area and fill in the low-cutoff freq in the popup-window. Let the mouth area be calculated by hornresp.
Maybe the impendance-ripples you get could be from a too small mouth area?
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Old 4th February 2005, 07:37 AM   #16
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Quote:
Originally posted by Cordraconis
There are two questions I have for you:
- Can you still remove the back volumes you have made? I think I've seen you made them out of brick walls.
- Would you like to try (maybe only one of your horns, for comparison ) to make a temporal back-and-front chamber to check my sim? Maybe you can hear the few dB more efficiency from the prediciton.
Yes it is easy to reduce the back volume and it is also possible to make a front volume. The problem when reducing the back volume is the low frequencies extention. I will try that when my room is ready, it is still under construction.
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