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Old 12th June 2012, 07:43 AM   #2701
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Quote:
Originally Posted by AndrewT View Post
What is the "best" data entry order?
Hi Andrew,

The only time that data entry order becomes important is when you wish to convert driver Thiele-Small parameter values to their electro-mechanical equivalents. In this case, the correct sequence for entering the driver T-S parameters is Sd, Cms, Mmd, Re, Bl, Rms. Use the Tab key or Enter key to automatically achieve this order.

Kind regards,

David
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Old 12th June 2012, 08:26 AM   #2702
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Specs were from this thread Advice required for low frequency bass.

Click the image to open in full size.

I converted the RMS 8.29 g/s to equal .83 newton.sec/m that Hornresp uses. I did a search to see what the conversion was and it said /10 so thats what I did not really knowing if that was the right conversion.

Hence my suggestion for a simple converter in the program for when the specs aren't provided in the same units, and not sure of the right conversion.

Why Rg = 4 not sure the amps I have are capable of a 4ohm load.
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Old 12th June 2012, 08:51 AM   #2703
Kolbrek is offline Kolbrek  Norway
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Quote:
Originally Posted by Silent Screamer View Post
Why Rg = 4 not sure the amps I have are capable of a 4ohm load.
Rg is the output impedance of the amplifier, not what the amplifier is designed to drive. Tube amps can have high output impedances, but usually not more than a couple of ohms. For transistor amps, you can set Rg=0.

Bjørn
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Old 12th June 2012, 09:04 AM   #2704
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Thanks guys for the help... slowly getting something that looks like a sub in Hornresp.
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Old 13th June 2012, 07:15 AM   #2705
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Originally Posted by Silent Screamer View Post
Hence my suggestion for a simple converter in the program for when the specs aren't provided in the same units, and not sure of the right conversion.
Hi Silent Screamer,

The existing Hornresp Calculate Parameter tool can be used to find the value of Rms as follows:

1. Set Cms = 3.10E-04 m/N as given in the specifications sheet.
2. Double-click on the Rms value in Edit mode.
3. Enter fs = 24.4 Hz as given in the specifications sheet.
4. Enter Qms = 2.54 as given in the specifications sheet.

The value of Rms is calculated by Hornresp to be 8.28 N.s/m. Note that this is very close to the numerical value given in the specifications sheet, but with entirely different units. The internationally accepted standard unit for mechanical resistance is newton.second/metre - I have no idea where g/s comes from.

Kind regards,

David
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Old 13th June 2012, 08:05 AM   #2706
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Hi David if someone like you doesn't know what hope does a newbie like me have

Funny but I kind of fell over that conclusion when I double clicked on one of the other boxes and it started asking me questions, and then it popped up 8.28, so I figured the conversion I found online must have been wrong or I interpreted it wrong.

Tried to find the website that I found previously and can't, but I did find this in my travels... Lowther PM6A In Back-Loaded Horns

5. RMS, Nm/s

So far the most confusing. Newton * sec / meter, or NS/M
For starters, many sources provide RMS in KG/S.

1 kg/s = 1000 g/s

assuming N = G * M / S^2, we get 1 G/S = 1 N * S^2 / M * S = N * S / M.
Thus, 1 kg/s = 1000 Ns/m

But this is not all yet, as some sources provide Rms in Kg/s and some - Rme in N*s/m, and these do differ, yet not by the factor of 1000. Various sources claim Lowther RMS as .4 to .5 KG/S. What to do? when RMS = 400 entered in hornresp, SPL curve is clearly bad.

So if 1 kg/s = 1000 g/s and 1 kg/s = 1000 Ns/m, then they are the same unit of measure.
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Old 14th June 2012, 07:46 AM   #2707
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Originally Posted by Silent Screamer View Post
Hi David if someone like you doesn't know what hope does a newbie like me have
Hi Silent Screamer,

I was a bit careless with my wording - I should perhaps have said "I have no idea where the value of g/s comes from" rather than "I have no idea where g/s comes from" :-).

The unit derivation itself is quite straightforward - but not quite as you have shown.

Rms = N * s / m

N = kg * m / (s ^ 2)

Therefore Rms = [ kg * m / ( s ^ 2) ] * [ s / m ]

Which can be simplified to Rms = kg / s by cancelling out m and s as appropriate.

Note that 1 kg / s = 1 N * s / m not 1000 N * s / m

It would seem that the specification sheet is in error - the 8.29 value given for Rms should be in units of kg/s, not g/s.

Kind regards,

David
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Old 14th June 2012, 08:11 AM   #2708
NEO Dan is offline NEO Dan  United States
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It might be nice to have motor force displayed at the bottom of the screen when you hover over bl and re, I think it's BL squared /Re. From there force per area and acceleration are easy... Force per area and compression ratio could/would be an interesting metric to observe.
You have throat pressure already though.
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Old 14th June 2012, 10:22 AM   #2709
Mark Kravchenko --- www.kravchenko-audio.com
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Hey throat pressure is your friend. Very useful when designing near the bleeding edge of efficiency.
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Old 15th June 2012, 06:19 AM   #2710
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Originally Posted by NEO Dan View Post
It might be nice to have motor force displayed at the bottom of the screen when you hover over bl and re, I think it's BL squared /Re. From there force per area and acceleration are easy... Force per area and compression ratio could/would be an interesting metric to observe.
You have throat pressure already though.
Hi Dan,

Making throat sound pressure data available is about as far as I am prepared to go :-). Diaphragm peak velocity and acceleration values are included in the diaphragm displacement chart sample results.

Kind regards,

David
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