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Old 24th November 2010, 10:25 PM   #1461
jwmbro is offline jwmbro  United States
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Hi, first of many thanks to David, for making this amazingly powerful program, which I am only beginning to understand.

I originally just downloaded it, because all the Tapped Horn designs in the Subwoofer section had HornResp parameters included, so it was an easy way for me to vary the input power into their designs and see how they simmed. However, after reading some tutorials, and getting to know the programm a bit better, I realized that it was capable of so much more than (Tapped) Horns, and I'm slowly beginning to replace WinISD with HornResp for closed and vented boxes.

Anyways, what I'm trying to do, is simulate a Linkwitz style Dipole Woofer, and I'm not sure if I'm entering my parameters correctly. Can somebody take a quick look at my Parameters vs. my Schematic, and tell me if I'm going in the right direction with this.

Click the image to open in full size.
Click the image to open in full size.

The bend on the far right is supposed to represent the 25mm where the side walls of the enclosure continue, but the dividers are gone. Ideally I would have wanted to make a similar section on the left side, but there's no option to add two segments behind the woofer. I'm not sure how important these sections are though, ie how much effect they'd have on the sim. Edit: I resimmed without the right expansion section, instead making L12 2.5cm longer, and the only changes were some minor differences outside of passband (intended xover around 80~100Hz).

The other thing I'm unsure of is how long I should simulate L12 & L56 as. I used the distance from the back wall to the front wall (ie 238mm) However, perhaps I should be measuring from the center of the driver to the opening, which would be only about half that length. Hope somebody more knowledgeable about these kind of sims can shed some light. Edit2: changing this to 14cm doesn't change too much below 100Hz (even shorter and you start to lose output in the bass region). So is it safe to conclude that this simply doesn't matter?

Also, I have a further question. The Woofer I'm using is a Dual Voicecoil (DVC) design, so I simply used Re/2 and Le/2 to indicate a parallel connection of the voicecoils. Obviously Sd is invariant, regardless of how the coils are wired. However I'm a bit unsure about the other 4 parameters (Cms, Mmd, Bl, Rms), especially considering Bl apparently has something to do with the voice coil length. Do I need to change any of those as well?

Thanks in advance for the guidance!
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Last edited by jwmbro; 24th November 2010 at 10:34 PM.
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Old 25th November 2010, 01:14 AM   #1462
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by jwmbro View Post
...Hi, first of many thanks to David, for making this amazingly powerful program, which I am only beginning to understand...
Hi, FYI: Just a test and a template to be copied:

b
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File Type: jpg 2xMCM-552185-H-frame-test.JPG (203.1 KB, 640 views)
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Old 25th November 2010, 04:59 PM   #1463
tb46 is offline tb46  United States
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Default PPSL

PPSL in Hornresp

Hi David,

I'm trying to model a PPSL, e.g.:

Klipsch Horn Woofer designs.....

Obviously, I could just model it as a BR, but that does not account for the front chamber (plenum). The OD horn looks like it may be the better choice, but when I read the help file I get the impression, that the rear chamber vent may be returned into the horn at the horn throat, which I guess would be S1.

It is nice to be able to model the front chamber of the PPSL as an OD (driver entry point at S2), and it would be great if the rear could be vented like a BR, or-even better-like a CH using the fourth horn section.


Regards,
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Old 26th November 2010, 06:42 AM   #1464
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Quote:
Originally Posted by tb46 View Post
The OD horn looks like it may be the better choice, but when I read the help file I get the impression, that the rear chamber vent may be returned into the horn at the horn throat, which I guess would be S1.
Hi Oliver,

I'm not sure that I understand the PPSL design correctly, but in an attempt to clarify the Hornresp OD horn options:

1. Add a new record using the default record as the parent.
2. Double-click Nd to select OD.
3. Double-click Fr to select Ap and note the message in the status bar panel at the bottom of the input screen - Ap and Lpt specify the port tube in a vented rear chamber. See also the red description in the first screenprint attached (Ap.png).
4. Double-click Ap to select Ap1 and note the message in the status bar panel at the bottom of the input screen - Ap1 and Lpt specify the port opening between a throat chamber and the entry into the horn at S2. See also the red description in the second screenprint attached (Ap1.png).

In other words, Ap is not the same as Ap1 :-).

Hope this helps.

Kind regards,

David
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File Type: png Ap.png (18.1 KB, 587 views)
File Type: png Ap1.png (18.1 KB, 145 views)
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Old 26th November 2010, 04:35 PM   #1465
tb46 is offline tb46  United States
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Default PPSL and Rear Chamber Vent

Hi David,

Thank you for the explanation. Looks like I got it correct to begin with, I just didn't want to pass along information while I still had questions.

I had not noted the difference between Ap and Ap1. That adds another option, nice.

Thanks again, Regards,
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Old 27th November 2010, 01:50 AM   #1466
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by bjorno View Post
Hi, FYI: Just a test and a template to be copied:

b
Hi, thanks for the help, also thanks for correcting my Sd, not sure where I picked up the wrong value.

I played around, and no matter how big or small I make the baffle, also when I compare your method of modelling to mine, the simulation below 100Hz seems to remain exactly the same.

Perhaps I'd need Edge to simulate this properly, or does it really not make a difference at all? I can hardly believe that....

What however does make a huge difference (unless I'm modeling this wrong), which surprised me, is switching from series-parallel to parallel-series connection (using two dual voice coil drivers). Is this really such a huge change due to the different inductance of the different wiring configurations? I would have thought it would give 0 net change (as the total inductance seen by the amp remains the same), but perhaps I would have thought wrong?

Click the image to open in full size.

Would the other parameters perhaps somehow measure thus differently when measured with the voicecoils in series, that the simulation would end up exactly the same again?
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Last edited by jwmbro; 27th November 2010 at 02:15 AM.
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Old 27th November 2010, 02:26 AM   #1467
soho54 is offline soho54  United States
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Just input the single driver specs using the voice coils as measured, and select series/parallel in HR. If you want to use a different voice coil setup, you will have to adjust the other parameters. More than Re and Le are altered when making this switch.

Last edited by soho54; 27th November 2010 at 02:29 AM.
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Old 27th November 2010, 02:35 AM   #1468
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by soho54 View Post
Just input the single driver specs using the voice coils as measured, and select series/parallel in HR. If you want to use a different voice coil setup, you will have to adjust the other parameters. More than Re and Le are altered when making this switch.
Thanks, I figured as much.

So that begs the question - would the two options simulate the exact same? Or would there really be differnces (though not as big as my incorrect simulation would indicate)?
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Old 27th November 2010, 01:02 PM   #1469
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by jwmbro View Post
Thanks, I figured as much.

So that begs the question - would the two options simulate the exact same? Or would there really be differnces (though not as big as my incorrect simulation would indicate)?
----------------------------
Hi James,

Answer for the question above: Yes, but levels/load would of course be different if not also changing the wiring:
See my new comparison that only uses different coil hook ups but not changing the wirings as should be done to be correct.

post# 1466:

Quote:
I played around, and no matter how big or small I make the baffle, also when I compare your method of modelling to mine, the simulation below 100Hz seems to remain exactly the same.
The reason why you get the same response is you are only modeling the drivers into IB, i.e. the rear of the drivers are terminated into an infinite(closed) volume. To sum both rear and front contributions: you must after pressing the 'Calculate' button and choose 'SPL' response also click on the 'Tools' menu and press the 'Combined' response and enter the path difference, too.

Quote:
Perhaps I'd need Edge to simulate this properly, or does it really not make a difference at all? I can hardly believe that....
The 'Edge' program cannot model your enclosure including the specific drivers in use.

Quote:
What however does make a huge difference (unless I'm modeling this wrong), which surprised me, is switching from series-parallel to parallel-series connection (using two dual voice coil drivers). Is this really such a huge change due to the different inductance of the different wiring configurations? I would have thought it would give 0 net change (as the total inductance seen by the amp remains the same), but perhaps I would have thought wrong?..Would the other parameters perhaps somehow measure thus differently when measured with the voicecoils in series, that the simulation would end up exactly the same again?..
There should be no difference(but the relative levels) when if 'switching from series-parallel to parallel-series connection' but a small difference in the entered TS parameters due to program round up effects.

To change from paralleled coils to series connected:
Click Sd and save the information of the calculated primary TS parameters, then double the BL value , Le and Re should also be quadrupled.
Click on Cms and enter the saved Vas value:
Click on Rms and enter saved fs and Qms.
Last:Check Mmd by entering fs again.
Compare the saved primary TS parameters by clicking on the Sd again,there should be no difference.

Note: In reality when using measured series/parallel connected coils:
All parameters are slightly off the theoretical as used here above, but if used, should return almost identical plotted graphs in HR,only very small (benign)deviations should be presented.

b

PS: If you seriously really believe in this type of enclosure for use as sub enclosures:
I urge you to invest in MJK:s programs that would model this type of enclosures at another more useful level by including room effects, active/passive filters and enclosure damping and so on...and complement the outcome from HR with the features not found in MJK:s program.
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Old 27th November 2010, 09:51 PM   #1470
jwmbro is offline jwmbro  United States
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Thanks, I've been planning to get the MJK sheets for some time ($25 is not really the issue), however obtaining a MathCad program has thus far hindered me. But that's not really for this thread I guess.

One more thing though: You are of course right, running in Series-Series-configuration will give a 6dB level shift vs Series-Parallel. But that wasn't quite what I was talking about. I was talking about using a Parallel-Series-configuration instead of Series-Parallel. ie keeping the net impedance at 8Ω, and not bumping it up to 32Ω. ie. on the right image it should read Nd: 2P.
I take it in that case the output must be identical then, if I'm now finally simming correctly.

For what it's worth, I'm not really considering pursuing the ripole style option with these drivers, but I was thinking, depending on how they sim, no harm in building a cheap mdf/particle board test cab.
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Last edited by jwmbro; 27th November 2010 at 10:01 PM.
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