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Old 2nd September 2013, 03:14 PM   #21
DrBoar is offline DrBoar  Sweden
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I was refering to your simulations and my measurements. I phrased that oddly I know. A more natural way would be "my measured curves is in close agreement with the model". But from scientific point that is nonsense, IRL is what it is, then a model can be in agreement with reality, not the other way around. Frequency response is measured with Dayton Omnimic.

Also with the IMF modeling it looks good but it seems that the pipe contributions are exaggerated. If you could lower the pipe output by 5 dB or so?
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Old 2nd September 2013, 03:24 PM   #22
xrk971 is offline xrk971  United States
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OK, understood. I can't lower the pipe output - it is turned on by selecting the output switch to show sound pressure at the radiator face (the plane of the pipe where it exits into the room). Is your mic measurement at the exit plane of the pipe?

I am not sure what I am doing wrong but the single-fold case is not agreeing at all. Are your dimensions in the sketch correct because I get the main bass peak at about 75 Hz with the dimensions you provide (see below). ?
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Old 2nd September 2013, 03:48 PM   #23
DrBoar is offline DrBoar  Sweden
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75 Hz is less than 1 m pipe length? Please note that the internal hight is 0.82 m so the geometric length of the pipe must be more than 1.5 m and with 5:1 taper that should be well below 50 Hz. My guess that is a for a pipe of 0.82 meter in lenght not internal hight.

I'm off to battle that middle age spread
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Old 2nd September 2013, 09:49 PM   #24
xrk971 is offline xrk971  United States
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Default Sim of DaLine - again

I found a typo in my earlier sim's geometry - sorry about that. I think the three harmonic peaks have similar amplitudes now, but the fundamental freq is higher at 50 Hz.

Here is the measurement:

Click the image to open in full size.

This is the sim with the T/S params as measured:

Click the image to open in full size.

This one is too far off - must be something wrong in the sim still. I will look at it again later when I have some time.
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Last edited by xrk971; 2nd September 2013 at 10:15 PM.
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Old 2nd September 2013, 09:54 PM   #25
xrk971 is offline xrk971  United States
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Default Sim of 1-Fold TL

I found the same typo in the 1-Fold geometry so here is the simulation again.

This is the measurement:

Click the image to open in full size.

And here is the sim with the measured T/S params:

Click the image to open in full size.
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Old 2nd September 2013, 09:59 PM   #26
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Okay guys, explaing to me again what are the red and black traces?
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Old 2nd September 2013, 10:11 PM   #27
xrk971 is offline xrk971  United States
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Black is direct radiation from driver and red is vent radiation - at the plane of cone or vent. Green is combined output 1 m away. Note that this color convention is for purposes of comparing with Dr Boar's plots. Usually I have red as direct driver radiation and green as vent, and black as combined in all my other sims posted elsewhere.
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Old 2nd September 2013, 10:42 PM   #28
pkitt is offline pkitt  United States
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I calculate the 1/4-wavelength resonant frequency for a pipe length of 1.64 meters and tapered at 5:1 to be ~37 Hz.
Paul

Quote:
Originally Posted by DrBoar View Post
75 Hz is less than 1 m pipe length? Please note that the internal hight is 0.82 m so the geometric length of the pipe must be more than 1.5 m and with 5:1 taper that should be well below 50 Hz. My guess that is a for a pipe of 0.82 meter in lenght not internal hight.

I'm off to battle that middle age spread
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Old 2nd September 2013, 11:33 PM   #29
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by pkitt View Post
I calculate the 1/4-wavelength resonant frequency for a pipe length of 1.64 meters and tapered at 5:1 to be ~37 Hz.
Paul
The revised sim in post 25 has 37 Hz right on.
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Old 3rd September 2013, 03:26 AM   #30
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Took your specs, mixed with the peerless specs and modeled this. Problem is the driver only has an Xmax of 2mm. This is easily exceeded with a few watts without a high pass which defeats the point of going TL. Even then, this looks to more suited for use as a midrange than a midbass and would be better suited for a sealed box.
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