Collaborative Tapped horn project - Page 277 - diyAudio
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Old 20th January 2009, 11:03 PM   #2761
djk is offline djk
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http://www.acronymfinder.com/PITA.html

Bookmark this and use it as needed.
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Old 20th January 2009, 11:36 PM   #2762
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Quote:
Originally posted by FlipC
tinitus

A mock diagram would be taking the picture you posted and inputing the HR data points into it. IE labeling S1/S1/Con1/S3?S4/Con2 etc.

Somehow it sounds like you are better at it, as I have no clew about what to do


Very long ago I asked about whether it would be possible to mount a big woofer in the mouth of a very big quaterwave
I had no clew what so ever, but a few people picked it up and started to discuss the Danley patent...so yes, it would really please me to see this Tapped-ACE get somewhere
It may not be different from the ordinare tapped, but offsetting the "V" a bit, like its done in the original quaterwave, may be doing something, maybe
Besides the "compressed" pushpull is inspired by JLH, and I think of his design as a really genious way of making a pushpull at its best, dissplacement doubles and both drivers seem like they are very evenly loaded, tied together
Only this one is really straight forward and less complicated, yet transistion to throath is even smoother still
But I would never have thought of it, havent I seen the JLH

Actually Im known to just toss the wood together making horns from what I feel is right, surely not the proper way, but seems to work ok as I have build horns from I was around 14, but could most like be much better with todays software
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Old 21st January 2009, 03:13 AM   #2763
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Reading a few pages a day, I'm almost all the way through but haven't noticed the following issue addressed yet, or maybe I skimmed right over it.

A tapped horn will have dramatically different frequency response depending on where you put it according to the following models. For example, the first 2 graphs here are the 18sound driver mentioned several times. The first graph is relatively flat (could be flatter still) all the way up past 200 hz, but the second one is not even close. The only difference is the top one is .5 pi, the second is 2 pi.

Click the image to open in full size.

Click the image to open in full size.

For me, this is the probably the final straw, that extra octave or so at the top end is just too tricky. Even if you pick the right driver and model a nice flat bandwidth, it would seem that it's all shot if you put it the wrong spot in the room. The upside of that is if the bandwidth is not needed, it looks like the box can be a whole lot smaller. The following model is the same maw15 from the last model a few posts ago, but now it's only 175L (105L smaller than last time), at the cost of about 1 db and a few hz bandwidth. I'm almost confident enough about design considerations and compromises to pick a design and build, but the drivers are still in the mail.

MAW15 tapped horn, 175L, 800W
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Old 21st January 2009, 04:19 AM   #2764
FlipC is offline FlipC  United States
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This would be the case with any subwoofer.
But why so many in the HT/hiFi world take room measurements and either build to suit or EQ accordingly.


tinitus
Sorry but even though I ahve thought about it I am unsure how you would go about trying to model your layout in HR. I can only assume someone could do it in Akabak but I am just learning that.

The mother would have to be behind the driver
on the left hand side. You would have a compression chamber in between that is ported to the path so what effectively becomes S1. Also in a TH the rear radiation becomes in phase due to the travel it makes back and forth. But since the compression chamber makes it so you have 3 entry points instead of 2 Im clueless.

Someone mock this up !
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Old 21st January 2009, 04:47 AM   #2765
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Quote:
This would be the case with any subwoofer.
No. A sealed or ported box does not exhibit dramatically different modelled frequency response based on changing only .5 pi and 2 pi like that.
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Old 21st January 2009, 07:54 AM   #2766
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"A sealed or ported box does not exhibit dramatically different modelled frequency response based on changing only .5 pi and 2 pi like that."

Says who?

http://www.jblpro.com/catalog/suppor...pe=3&docid=837

http://www.jblpro.com/catalog/suppor...pe=3&docid=626
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Old 21st January 2009, 03:47 PM   #2767
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Quote:
Says who?
That was me, I said it.

Ok, all joking aside, you are both right I guess but missing my point. Frequency response does change for any box in these different environments, but see the enclosed example to see that although frequency response shifts a bit in this closed box when moved from .5 to 2 pi, it stays quite flat. In other words, the frequency response does not suddenly become excessively bumpy just because you moved the box, the whole bandwidth is shifted and slightly different but still very usable. In the tapped horn example posted previously the response becomes unusable (imo) just from moving it out of the corner.

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Old 21st January 2009, 06:52 PM   #2768
FlipC is offline FlipC  United States
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Why I model 1/2 space.

Plus if you noticed I mentioned that mine do not have the perceived spike at that 200 Hz area that HR predicted. Though yours starts at 100 Hz. I would play around and flatten it out a bit more. But I assume that this isn't something you were going to build but rather an example of the statement.
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Old 21st January 2009, 07:02 PM   #2769
tinitus is offline tinitus  Europe
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Quote:
Originally posted by FlipC

tinitus
Sorry but even though I ahve thought about it I am unsure how you would go about trying to model your layout in HR. I can only assume someone could do it in Akabak but I am just learning that.


Its strange, I know
But actually I would think that the 2 split lines ought to be considered as one, and the output from both present summed output...at least I cant see it any other way

So why have they offset the "V" loadline...means it supposed to do something...but what

Could it be that they wanted to spread the unavoidable and unwanted internal ressonances, instead of having two completely alike ressonances summed...I actually think I have heard something like that before

If its not significant one could just do it completely symmetrical, and do with the possible advantage of a mutual compression chamber fore the two drivers, have the optimal pushpull, and still doubled displacement

My only reason for looking at this ACE design is to have the brilliant JLH pushpull chamber, and still being simple and easy to build
Or else the even simpler standard tapped would be preferred

Thanks fore attention
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Old 21st January 2009, 07:28 PM   #2770
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Quote:
Post #2768
Why I model 1/2 space.
Ok, so you design for flat response in halfspace. Move it into a corner and it won't be anywhere close to flat anymore. Then what?

Quote:
Plus if you noticed I mentioned that mine do not have the perceived spike at that 200 Hz area that HR predicted.
I realize there will be differences between modelled and measured performance, and WC and TD are always saying you need to build to confirm, and then build again (and again, and again and again...) until you get the response you want. I'm just trying to gain a basic level of understanding of how this works before spending a fortune on wood and thousands of hours on things that can be sorted out with modelling before advancing to the build and measure and repeat process.
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