Hornresp Diaphragm Displacement |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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OFC.. Thanks david. Response wise sligly closer to measurments, Impedance further from measured. displacement reduced by couple of mm per hz. |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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if the drivers are facing each other you need several litres of front chamber volume to represent the air inside the speaker cones. has a small effect on response.
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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also, the length of the rear chamber is not 86cm. if you want to model resonances in the rear chamber it should be the average distance from the back of the cone to the wall behind it (in this case the side of the speaker). to model the interaction of the front and rear output I thought you would want the chamber length to be the average distance from the rear of the cone to the centre of the rear vent. this would enable modelling of phase differnces and interference between the horn and vent outputs. However, trying it now, with the 'masked' option selected, the depth of the rear chamber does not seem to have any effect on the combined output implying that the rear path length is not being used to model the combined output.
Perhaps David can clarify how this works? |
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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Edited by mobiele eenheid - 23 January 2018 at 2:42pm |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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yes, but there are two effects. one is the resonances which occur in all speakers with a rear chamber - sealed, FLH etc. the other is the interaction between the front and rear outputs. I thought that the masked option only disabled the first one. |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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Just tried this and found electrical impedance to have increased considerably from 18 sound plot. was infact very similar before at 86. But good to know how it should have been done. Not that I understand why the result is further from real world tho. Edited by SouthwestCNC - 23 January 2018 at 3:00pm |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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revised
-15ltr from VRC for volume taken up by driver. Ignore my last comment regarding impedance, I was looking at this cab simmed as a single in 1. pi, half figures. In this sim the impedance was higher. this down to the half horn do you think? Edited by SouthwestCNC - 23 January 2018 at 3:22pm |
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gen0me
Young Croc Joined: 20 February 2016 Location: UK Status: Offline Points: 999 |
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Second one is "combined output" distance in acoustical power options or patch length in wizard in chamber options. First one is not important in bandpass can show up in bass reflexes as they play higher. Btw do you calculate mmd or put it as mms? |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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I calculated.. should i have used mms? |
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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No, Mms is higher as Mmd, so calculating is the way to go.
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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from the hornresp help file: " The path length from the rear side of the driver diaphragm to the port outlet is assumed to be equal to Lrc plus Lpt, as shown in the schematic diagram. The distance from the port outlet to the listener can be adjusted if necessary using the path length difference parameter. A positive value for path length difference increases the listener distance. The path length difference is the distance from the port outlet to the listener minus the distance from the direct radiator diaphragm to the listener. The difference is positive when the distance from the port outlet to the listener is greater than the distance from the direct radiator diaphragm to the listener." |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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so rear chamber length should be the average distance from the cone to the start of the vent. if there is no vent make the rear chamber length the distance from the cone to the rear wall parallel to the driver. Is that the right way to use Hornresp?
Edited by snowflake - 24 January 2018 at 12:15pm |
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