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Old 30th October 2008, 08:01 PM   #1
FlipC is offline FlipC  United States
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Default Hornresp Class

So I want to have a better more solid understanding of Hornresp.
I have read the help files and the 2 "manuals" but still need more info. So I thought what better way than through example using a TH design. So all you Hornresp experts chime in on what I think I understand correctly and those that I don't at all.
(reference the help file and DIYAUDIO Hornresp manual )

Ang = the place of usage. Simple. Most should be done in 1 Pi as most speakers will be sitting on a floor in the center-esk of a room.
Eg = Amplifier voltage. 2.83 is 1w@1m but for testing you can change.
Rg = the working OHM output of an Amplifier. IE your using an 8 ohm driver. Though doesn't this change based on freq. range being produced? How does this effect outcome ?
Fta = horn mouth flare angle (see figure 1 part A) So you can see changes when you adjust the angle of the speaker. (?) Seems that higher/steeper angles give better top end response where as lower/flatter gives better low end roll off.

If you already have a driver you want
to use skip to the bottom portion.

Sd, CMS, Mmd, Re, Bl, Rms, Le are all speaker specifications.
Look up your speaker or use a tester like WT3 Speaker Tester
The part after Le is for what type of horn you are making. In this case click on it till it reads TH

Back to top section.
S1 = Horn segment throat area. IE the hole the speaker fires into.
This is a direct correlation to the Sd of the speaker you are using. The difference between the 2 is the compression ratio. IE if your speaker has an Sd of 800 and you want a 1:2 ratio then S1 is 400.
Or 1/2 of 800. If you want a 1:4 ratio then S1 would be 200. The compression ratio can do allot in terms of limiting cone excursion since the rear fires into space. ( correct ?)

Next is S2. This is S2a area squared cm + S2b area squared cm (red lines)
S3 and S4 are S3 + S2b | S4 + S3 respectively.


Now the part which is the L12/L23 etc in the help file.
For a TH the L12/L23 becomes CON (conical) as in the design in Figure 1 is a CON build. Exp would be the horn schematic in Hornresp. So for the 4 segment horn we have illustrated we will have CON inputs for S2, S3, and S4.
Now one thing I am unsure of is if we measure from the S (IE S2a) lines straight or is it supposed to be on the same angle of the horn segment to which you are measuring? Though would be only slight difference ?

Bottom Section of Hornresp. I have some questions about these:
Vrc, Lrc, aren't used for TH's as the rear of the driver is not enclosed.
Ap and Lpt represent the Throat Chamber
(where the driver fires into)
AP states "Chamber port cross-sectional area (cm sq). I thought this would be the same as S1 IE the area the driver fires through.
Lpt states "Chamber Port Tube length" Is this the length of the first segment (see diagram) or would it be the distance from the driver to the first segment? (thickness of the wood)
Now we have VTC. Now this would be the cubic area in segment 1 of our diagram measured in liters?
Atc = ?

Quote:
"Offset driver and tapped horn systems can now have a connecting port between the throat chamber and the entry point into the horn"
I assume that means the AP and Lpt being transferred from rear chamber to throat (front) chamber for TH's. But again what is the difference between this and S1 ?

Also how do you change where in the mouth the driver is located ?
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File Type: jpg hornresp-example.jpg (31.3 KB, 797 views)
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Old 31st October 2008, 02:56 PM   #2
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Location: Rotterdam, NL
You might wanna read the wiki again, that should short your problems with Vtc (volume throat chamber) and Atc (area throat chamber). Vtc is in cm^3, 1000 cm^3 is one litre.

Ap (area port) and Lpt (length port tube) are to specify the dimensions of the Helmholz -resonator (or port) to be mounted into the Vrc (volume rear chamber), if wanted.

Rg is the amp's internal resistance, you might want to add the resistance from the cable between the loudspeaker and amp aswell. Usually this together is (fairly) below one Ohm.

Also you might not be aware that for tapped and offset horns S2 instead of S1 sets the compression ratio.

Based upon some of your question I get the idea that you should just simulate a lot more. Most question will answer themself within the first day's / week.

Regards
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Old 31st October 2008, 09:27 PM   #3
FlipC is offline FlipC  United States
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Join Date: Aug 2008
Rademakers
Thank you for replying but you missed the translation and/or you yourself seem to have a few misunderstandings of Hornresp.
My statements and questions are only for a TH. Nothing else.
Reason being is some things change in Hornresp. Like Ap/Lpt.
They no longer represent the REAR chamber but rather the FRONT.

How can S2 represent the compression ratio ?
Other people have stated that S1 represents the compression ratio.
Which makes since SINCE you take the drivers cone area (Sd) and fire it through S1. So if S1 is half the size of Sd then you have a 1:2 compression ratio.


Quote:
Rg is the amp's internal resistance, you might want to add the resistance from the cable between the loudspeaker and amp as well. Usually this together is (fairly) below one Ohm.
Why would it say "output" in the Help file?
IF it is indeed the amps internal resistance, what would this effect in terms of speaker box estimations as you would have to have specifics about the particular amplifier you were going to use.
Even if it is not the amps internal but rather the external resistance put upon the amp, isn't this covered with the Re input?

Someone else want to chime in ?
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Old 31st October 2008, 10:09 PM   #4
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Location: Pacific Northwest
Quote:
How can S2 represent the compression ratio ? Other people have stated that S1 represents the compression ratio. Which makes since SINCE you take the drivers cone area (Sd) and fire it through S1. So if S1 is half the size of Sd then you have a 1:2 compression ratio.
Umm, not exactly.

The horn area opposite the driver in the simplest tapped horn model is represented by S2 at the throat end and S3 at the mouth end. From the Hornresp help file Note 8 on page 16 (WHICH IS HANDS DOWN THE BEST PLACE TO LEARN ANYTHING/EVERYTHING ABOUT HORNRESP):

"Driver entry points are at S2 and S3 for a three segment horn..."

So - "compression ratio" could then be described as Sd/S2. I am one who has used the term on this forum, and probably misused it. Ultimately - I do not even know if it matters all that much for home-use, but I have tried to keep S1 at Sd/4 or larger and S2 at Sd/3 or larger in my designs with generally good results.

Keep at it, you will figure this out. I'm still in the vertical portion of the learning curve too, I can barely keep up with learning all the cool new stuff between software revisions.
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Old 31st October 2008, 11:51 PM   #5
FlipC is offline FlipC  United States
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Ok
So using the diagram I posted (4 segment horn) and dropping the compression ratio question.

1.) Lpt states "Chamber Port Tube length" Is this the length of the first segment (see diagram) or would it be the distance from the driver to the first segment/chamber? (which Ap would be its area total)

2.) If Ap is the area to which the driver fires through to get into the first chamber, what is the difference between it and S1?

3.) Atc... OK someone give me a diagram and explanation on it!
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Old 1st November 2008, 01:30 AM   #6
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Location: Pacific Northwest
You're confusing things a bit.

Question 1 - No and no.

As I understand it (and I may be off base)

Lpt and Apt only come into play when there is an additional chamber (compression chamber) between the throat side of the woofer and the throat side entry into the horn at S2.

Lpt = length of the "port"
Apt = area of the "port"

The volume of this compression chamber is Vtc, the area is Atc.

The throat end of the horn is S1

Question 2 - the speaker fires through a hole, represented by Apt and Lpt, and as stated above, S1 is the area at the throat end of the horn

Sorry - no capability to make pictures with this machine (or my drafting abilities), but jbell did a nice job explaining the basic layout of a tapped horn a few weeks back.

jbell post
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Old 1st November 2008, 11:27 PM   #7
FlipC is offline FlipC  United States
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Join Date: Aug 2008
littlemike
THANKS! You just cleared up a bunch.

So Ap & Lpt would represent a box (chamber) the driver fires into that leads into the first segment of the horn. Giving this pic as an example
Ap/Lpt example. The drivers are firing into what Ap and Lpt represent?

Though what represents the area the speaker fires through?
I thought S1 represented this. But if it not what does? See pic to see area I refer to.


The JBell pics is great
Didnt think of doing a diagram like that. Now I know what S1 actually represents. Which answers the compression ratio mix up I was having.

Seems I had the wrong idea on a few points.
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Old 2nd November 2008, 05:54 AM   #8
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Location: Pacific Northwest
Quote:
So Ap & Lpt would represent a box (chamber) the driver fires into that leads into the first segment of the horn. Giving this pic as an example Ap/Lpt example. The drivers are firing into what Ap and Lpt represent? Though what represents the area the speaker fires through? I thought S1 represented this. But if it not what does? See pic to see area I refer to.
Close, but still not quite there.

As I understand it (bear in mind that I am still learning too)

Ap and Lpt describe the area and length of the "port" from the compression chamber to the throat-side of the horn at S2.

The chamber itself is represented by Vtc (sets the volume) and Atc (sets the area)

Drivers fire into the chamber (if used - not all designs use them)

The chamber is fed to the throat side of the horn through a "port" with area Ap and length Lpt

S1 is the area at the throat end of the horn. S1 has nothing to do with the area at driver entry or the area of the "port", it is simply the area at the throat end of the horn, just as S4 is the mouth of the horn.

Again - not all TH's require compression chambers.
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Old 3rd November 2008, 07:23 PM   #9
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Quote:
My statements and questions are only for a TH. Nothing else.
I understand,

Just bear in mind that Hornresp now has different uses (definitions) for horn parameters dependend if you're working with a "normal', a "tapped' or an "offset' horn. However the horn parameters are still the same, a port will always be a port.

If you know your way "overall' in Hornresp and something changes you only have to compare the change with the overall image of what you already know. That's why I thought that if I would re-define Ap and Lpt you would understand. I was wrong (no offence intended).

Quote:
Why would it say "output" in the Help file?
Synonyms, the next link should help: http://www.transcendentsound.com/amp..._impedance.htm

Quote:
3.) Atc... OK someone give me a diagram and explanation on it!
Hornresp officially models cillindrical horns. A chamber therefore has an volume defined by a lenght and area.

For the best diagram out there simulate two different Atc's (all else equal) and look for the result in the schematic Diagram.

Regards Johan
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