Simple Tapped Horn Tutorial using Hornresp - Page 3 - AVS Forum
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post #61 of 114 Old 01-18-2010, 09:44 PM
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Quote:
Originally Posted by Ricci View Post

ARTA

You can use the demo version free. Been trying to get acquainted with it myself. There's also HolmImpulse.

+1 on ARTA. Tons of post-processing options once you get the impulse. The included LIMP program does everything WT does and STEPS does distortion tests up to 6th order. Way cheap for what you get. It's like 90% of Praxis ($1K) at 10% the price.

Dennis H
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post #62 of 114 Old 01-18-2010, 10:52 PM - Thread Starter
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Thanks for the tips. I've been looking at ARTA, but sort of lost interest when I found REW. Once I got that working, I just stuck with it. Guess I'd better check for an update to REW. Seemed like I installed it just yesterday (actually more like a year ago...).

Anyhow - here is phase from the Woofer Tester 2 sweep.



Sorry - I only have a Woofer Tester 2 (but I use it a lot...), I wish I had the Speaker Tester or Woofer Tester Pro.
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post #63 of 114 Old 01-19-2010, 08:32 AM
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That actually tracks better than I thought it would. Hornresp really seems to miss on accounting for the complete interaction from the driver back wave. The peaks and dips are in the correct general positions though.

This is where AkAbak pulls away, but it overshoots slightly here like everywhere else.
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post #64 of 114 Old 01-19-2010, 11:02 AM
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Before I get too much flack about my phase primmer earlier... gotta love PMs.

People seem to be misunderstanding the application here, which means I didn't explain it well enough.

The info is in post 12, 13, and the often overlooked 16.

This is the quick/simple way to use the HR phase response graph to minimize phase shift.

The key mess up seems to be the use of the term "passband" instead of "total system usable bandwidth." I am sorry.

The thing is, you have to figure out the quarter wavelength of your horn, and this is the low limit. The upper limit is how high the driver could be used in the horn. IE, if the Fr doesn't begin to roll off until ~200Hz use 200Hz. When in doubt 120-150Hz will work.

If you use lilmike's posted HR inputs from post 42 you get a 414cm horn. This gives you an ~21Hz QW length. The FR graph seems to roll of ~200Hz, so you need to focus on the phase difference from ~21Hz-~200Hz. This will show around a 120deg phase difference total from peaks and dips. This lines up pretty well with the measured and AkAbak simulations. This isn't super exact, but it seems to always hold up.

Hope that clears it up a little.
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post #65 of 114 Old 01-19-2010, 11:13 AM
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I went back and added the high corners to post 12 & 13. Maybe it will make more sense now to everyone.
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post #66 of 114 Old 01-23-2010, 07:07 PM - Thread Starter
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OK, so I drug the example tapped horn into the living room this afternoon, set up the measuring gear, and recorded some in-room THD measurements. My method was to position the sub for a decent in-room response (have a huge dip in-room at 70 Hz), then set the mic at the listening position, and set up for some THD measurements using REW. I set the drive level for approx 90 dB at the listening position, which was approximately 3.3 volts drive to an 8 ohm load.

I used the REW generator and settings maxmercy and soho54 suggested, then stepped from 20 Hz to 120 Hz by 5Hz increments and recorded THD, THD+N, and 2nd-5th harmonics for each frequency. I have not plotted it up yet, but suffice to say, I could set the max for the axis at 10% and I wouldn't get close to the limit. I was pleasantly surprised.

So pleasantly surprised, I patched it into the system, grabbed a beer, and started playing music through it.

As it is an 8-ohm sub, I had to adjust the gain on the sub amp to match levels, but other than that - no Audyssey or anything like that - just as built - no tweaks, no nothing. It sounds great, and it plays plenty low (for a pair of cheap 8's).

I played a little bit of everything - Metallica to Junior Brown to Techmaster P.E.B. I heard a little complaint (though I couldn't duplicate it) when I was playing Mickey Hart's Umasha Strawberry Swamp Fever Remix at 105 dB (at the couch). Bass guitar sounds nice. Synth bass sounds incredible, and there is plenty of kick and chest resonance.

In a nutshell, I like it. My house sounds far worse than the sub. Everything rattles.

I'll get the THD and distortion components plotted up tomorrow. I just wanted to provide an update.
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post #67 of 114 Old 01-23-2010, 08:29 PM
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Very nice - wish I could drop by to hear it
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post #68 of 114 Old 01-23-2010, 09:05 PM
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Can't wait to see the THD results, thanks for doing this....I'm going to be starting my front-loaded horn build and horn tutorial very soon as well...I'll also be doing some THD measures....

JSS
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post #69 of 114 Old 01-23-2010, 09:39 PM
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Quote:
Originally Posted by lilmike View Post


Beautiful picture!
I wish I lived near there.
Well, maybe not too close.
After all, I see what you're building and I know it is going to shake some foundations and rattle some windows.
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post #70 of 114 Old 01-23-2010, 10:39 PM - Thread Starter
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Well, for what it is, it performs very well.

Remember my comment about these cabinets needing a high-pass? I meant it. Without a proper high pass, I did bottom the drivers on a few of the explosion scenes in Batman Begins.

I kind of expected that, as I had the movie turned up pretty loud, and I'm pretty sure the bass is still a bit hotter than the mains, I'll RTA things tomorrow to see.
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post #71 of 114 Old 01-23-2010, 10:44 PM - Thread Starter
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Quote:
Originally Posted by PassingInterest View Post

Beautiful picture!
I wish I lived near there.
Well, maybe not too close.
After all, I see what you're building and I know it is going to shake some foundations and rattle some windows.

Thanks. One of the benefits of living on a hilltop in the Puget Sound region. There is something great to look at in most directions.

Thankfully - the neighbors are not that close. My poor house was rattling and shaking quite a bit tonight.

This one is just a prelude, honest. Proper drivers are ordered, and proper subs are in the works. Assuming these drivers test similar to the published specs, this is gonna get fun.
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post #72 of 114 Old 01-23-2010, 10:47 PM - Thread Starter
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Quote:
Originally Posted by maxmercy View Post

Can't wait to see the THD results, thanks for doing this....I'm going to be starting my front-loaded horn build and horn tutorial very soon as well...I'll also be doing some THD measures....

JSS

Honestly - I don't exactly know if I did the THD right. I'm still trying to figure out how to present it all on one graph, I have a few ideas. I'll post what I have once I get it all plotted up and let everyone pick it apart.

Looking forward to the results of your build as well. I'll second the recommendation for the W8-740P, though the MCM 55-2421 is no slouch in a front-loaded horn.
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post #73 of 114 Old 01-23-2010, 11:55 PM - Thread Starter
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OK, so I couldn't wait.

Hopefully this effort was meaningful. If I've not done something properly, please chime in.

SPL and THD were measured at the listening position, approximately 10 feet from the corner the mouth of the sub was loaded into. Drive voltage (measured at 60 Hz with an 8-ohm resistor) was 3.38 V, about a watt and a half, which yielded an average SPL of 89 dB at the couch.

My house rattles. A lot. I'm sure the house rattles are part of the THD+N.

Once done with the measurements, I plotted up the SPL and then added a bar-chart showing my measured THD, THD+N, and the 2nd 3rd, 4th and 5th harmonics as determined by REW using the settings maxmercy suggested.

Anyhow - here's the chart. Hope the presentation is OK.



I also attached it as a pdf so the resolution is a bit better.

As you can see, my room is not at all sub-friendly (at least with only one). No EQ was applied and the amp gain remained constant. The amp used for the measurements is flat to below 20 (modified BASH 500). I used a different amp for the listening tests (and I still did not have enough of a high-pass in place...)

 

In room THD.pdf 8.173828125k . file
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post #74 of 114 Old 01-25-2010, 09:31 PM
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Very impressive at 25Hz!! This is some good output for the Voltage in. Great graph.....Interested to see what it will do with more power in...

So, what are the plans for the 'proper driver' sub? Driver? Tuning freq?

I have the 6.5" TangBand on order, should be getting down to business on it soon...

I also modeled the TB W8740P in a 20Hz horn....a dual-driver, 225 liter box should push the envelope of small, loud and low....but that is for later...

This weekend I'll have time to do the folding tutorial and get it posted up.


JSS
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post #75 of 114 Old 01-25-2010, 09:43 PM
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Max , I would like to see your sims with the TB W8

If at first you dont succeed , get a bigger hammer !
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post #76 of 114 Old 01-25-2010, 09:58 PM
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Quote:
Originally Posted by Rightbrained View Post

Max , I would like to see your sims with the TB W8

+1... I just cannot seem to get that driver to model well. Maybe I'm just trying too hard to make these easy to fold.
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post #77 of 114 Old 01-25-2010, 10:07 PM
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I havent had the time to try to learn hornresp so I havent modeled anything.

If at first you dont succeed , get a bigger hammer !
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post #78 of 114 Old 02-01-2010, 12:59 PM
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Lilmike. Having read your posts on appropriate drivers for a tapped horn, I'm wondering if you have looked at the AE TD12-H. It seems to have the qualities you described.
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post #79 of 114 Old 02-01-2010, 01:37 PM
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AE TD12-H

It models pretty well for me, though it tends to lose control of the excursion below the corner. Lets me use a nice, safe compression ratio too
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post #80 of 114 Old 02-01-2010, 01:49 PM - Thread Starter
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It models pretty well for me, though it tends to lose control of the excursion below the corner. Lets me use a nice, safe compression ratio too

Very true. Note how the low corner drops even further when you make S2 larger (approx 280)? This driver behaves pretty well in a tapped horn, though the excursion does blow up with the real low stuff.

The box is pretty big,though that is to be expected with anything that has any sort of efficiency at 15 Hz. If you do one, be sure to use a good highpass with it.
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post #81 of 114 Old 02-01-2010, 01:53 PM
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Quote:
Originally Posted by lilmike View Post

Very true. Note how the low corner drops even further when you make S2 larger (approx 280)?

I saw that - it was very nice to see

I modeled a 19Hz design with it that looks to hit 120dB in a corner.
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post #82 of 114 Old 02-01-2010, 02:25 PM
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Hey Mike--how about some more info on those Anarchy TH's!
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post #83 of 114 Old 02-01-2010, 02:51 PM - Thread Starter
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Just got off the phone with Mr Haskins. My Anarchys (and a Shiva X2 ) are on their way to me in the big brown truck as we speak. Since I could drive there (and back) in an afternoon on a single tank of gas, I should have them in hand tomorrow. I need to look at mounting options - the driver is big enough (and the horn is small enough) that I need to take the motor structure into account or it will choke the horn slightly.

I'm generally happy with the design, though I'd like to clean up the impulse a bit more. I have got the phase just about right, and I have nearly got it to the size I wanted. I spent all night trying to get it folded up - and failed. I still suck at sketchup.

I'll keep trying on the folds. Tapped horns are a little more complicated, in that the throat and mouth have to line up, so you have to fold both at once. I'm using the maxmercy approved method, I am just painfully SLOW at it.
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post #84 of 114 Old 02-01-2010, 02:54 PM
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It sounds like it is small--how much folding do you need to do? Can it just be a single fold over on itself? Hmmm still 6 ft. tall

Also, how high does it go before TH-wackiness sets in?
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post #85 of 114 Old 02-01-2010, 02:56 PM
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Quote:
Originally Posted by lilmike View Post

Just got off the phone with Mr Haskins. My Anarchys (and a Shiva X2 ) are on their way to me in the big brown truck as we speak.

That is the coolest thing I've heard all day

Besides the weather forecast, that is. While I'm somewhat lamenting the fact that I didn't win that 21" monster, it's probably for the best. I have enough on my plate already with the tapped horn projects.
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post #86 of 114 Old 02-01-2010, 04:03 PM - Thread Starter
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Quote:
Originally Posted by Fatawan View Post

It sounds like it is small--how much folding do you need to do? Can it just be a single fold over on itself? Hmmm still 6 ft. tall

Also, how high does it go before TH-wackiness sets in?

It is small - like under 2.5 cubic feet small. Not sure what the final dimensions will be - I'm going to let the fold sort of dictate that tonight rather than forcing things the way I have been.

With some damping and a typical plate-amp crossover, it should be usable to over 120 Hz, but no way to know till I build and measure and try a few alternatives. A good EQ might take things a little further.

A tall, skinny cabinet is tough - my L34 is really long. It will likely be rectangular. This one will not win efficiency contests, that is not what it is about.
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post #87 of 114 Old 02-01-2010, 05:01 PM
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Quote:
Originally Posted by Rightbrained View Post

Max , I would like to see your sims with the TB W8

RB,

Sorry, didn't see this before......

The TB W8-740P in a small, 20Hz OD (Offset Driver) FLH (Front Loaded Horn), single driver version in grey, dual in black, 20V in, corner placement:



But the excursion is out of control below 20Hz:



That's why the amp I would choose to power it/them that has a highpass that begins at 20Hz (see the end of the manual for freq response):

http://www.oaudio.com/docs/O_Audio_300W_manual_v1_2.pdf

Or just use a Reckhorn B2, eQ.2, or any other highpass to keep excursion under control below 20Hz....

Realistically, I would run 4 of them in a room w/o a highpass. at 100 liters modeled (approx 4-4.5 cu ft when built), they could be hidden away in ceiling corners and take up zero floor space...

JSS
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post #88 of 114 Old 02-03-2010, 06:44 PM
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try a driver with Qts ~.25, Lower than average VAS and and Fs about 1 octave (possibly 1.5 octaves) above what you want to tune the cab to. A strong cone is not a bad idea either.

just watch the lines on the wizard, what a nice program. Hats of to David
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post #89 of 114 Old 02-16-2010, 11:36 PM - Thread Starter
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Quote:
Originally Posted by Fatawan View Post

Hey Mike--how about some more info on those Anarchy TH's!

Wood is cut - finally!

Each horn takes a full 5X5 of 1/2 baltic birch. I'd originally planned to use MDF, but found good baltic birch for less than $30 a sheet so I went that route.

I'll work on the layout tomorrow, but I won't be gluing anything up till this weekend. Probably won't be done till late next week. I'll do a build thread when I am done with the building and testing.
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post #90 of 114 Old 02-17-2010, 06:04 AM
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Quote:
Originally Posted by lilmike View Post

Wood is cut - finally!

Each horn takes a full 5X5 of 1/2 baltic birch. I'd originally planned to use MDF, but found good baltic birch for less than $30 a sheet so I went that route.

I'll work on the layout tomorrow, but I won't be gluing anything up till this weekend. Probably won't be done till late next week. I'll do a build thread when I am done with the building and testing.

Excellent! Are you using one or two Anarchy's per enclosure?
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