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I thought out of polarity was the same as out of phase? Am I having a senior moment?:huh:
Yes, I think you're having a moment but the evidence is inconclusive. :)


Two drivers parallel in phase:


-------(-)----(-)
-------(+)----(+)



Two drivers in parallel out of phase:


-------(-)----(+)
-------(+)----(-)
 

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Yes, I think you're having a moment but the evidence is inconclusive. :)


Two drivers parallel in phase:


-------(-)----(-)
-------(+)----(+)



Two drivers in parallel out of phase:


-------(-)----(+)
-------(+)----(-)
Out of polarity. Out of phase would mean that the drivers would move in opposite direction. One driver moving out and the other moving in at the same time. They're mounted as one driver cone facing in and the other cone facing in to the back of the horn in the throat. If you wire them parallel in correct polarity + to + then - to - it would be out of phase.

Phase (waves)
 

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OK, I guess I worded my question wrong. I should have said if you change the polarity then you change the phase and so when you said +to+ and --to-- I didn't realise that the drivers were physically mounted out of phase with eachother. Makes more sense when I regained conscionsness.:doh:
 

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I was supposed to get mine yesterday but it didn't happen.:rolleyesno: I was all set for a weekend project to. Oh well, next weekend I guess.
 

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Discussion Starter #166
It's been a while since I've updated things here. I've been really busy. :sweat:


There has been a lot of activity concerning using damping to cut down the resonances out of the DTS10's intended range and how to address the cabinet resonances apparent in the DTS10 design. The main ones are at 54hz and another at about 100hz.


I went all around the driver baffle and on both of the driver hatches. I also did the chamber below the angled driver and up under the other driver. I also did all around the mouth area. Here are the close mic results. It cut into the response above 95hz a lot. I'm not very concerned with this as I don't plan to use the cab up above that point. Seems to lose a bit around 30hz as well but it's only a db or so. The 54hz spike is reduced by 3-4db. I used straight up egg crate foam. I probably went overboard with it but I figured that was the best way to see what the difference would be.

Gray is close mic'd, no xover, before.



The waterfalls of before and after.











I have pushed my DTS10 really hard (probably harder than anyone else) and while I had the drivers out I noticed that the 2nd driver that is mounted with the cone towards the center brace had apparently made contact with the "G" brace. This may have been what I heard on very heavy sine waves. It appears as if there is only about 0.625" of clearance before the surround / cone contact the brace. There was a clear white mark on the cone and surround evidencing the contact. I took the liberty of using a dremel tool to grind out another 1/2" of clearance so that this won't happen when driven hard with low freq. You may want to look into modifying the "G" piece with the kit to give an extra clearance for the driver excursion. It's the piece that goes underneath the inverse mounted driver. Tom has replied that the piece will be altered on future kits and enclosures to clear the driver during high excursions. Many people are also doubling up on the gasket for that driver to give additional clearance as well.

 

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Discussion Starter #168
From Tom Danley,

"Mike has taken the measurements according to the CEA 2010 criteria, like Illkka used except Mike measured at 2 meters for the values listed and we used a steady state sine wave instead of a tone burst..

These are steady state sine wave values (which is unavoidably harsh but we have not found an easy way yet to do it with a tone burst, with the test equipment we have.).
This is a pain in the rear too and we will re-visit this when we find an easier way to do it, but the weighted harmonic approach makes sense relative to perceptual masking..

So, anyway as of now, using a sine wave, one DTS-10 in half space, at two meters, reaches the following levels;
CEA 2010 Max RMS Output @ 2mtrs.
12Hz 102dB
16Hz 108dB
20Hz 109dB
25Hz 111dB
31.5 114dB
40Hz 114dB
50Hz 117dB
63Hz 115dB
80Hz 127 dB
Ultra low AVG 20-31.5Hz
111.3dB
Low Bass 40-63Hz
114.3
20Hz-80Hz AVG
115dB
I am keen to see how different two are, with our other Tapped horns there is a large improvement in the curve when you have two vs one.
Initially I had thought it would take two in a dedicated room, or four in a large room to reach the right fear factor.
When we can we will measure a pair the same way in half space, this will be significantly higher and produce a flatter response curve too..
Anyway, for those who were waiting for some comparable numbers, here are some to start with.
Best and happy listening.
Tom Danley"
 

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Discussion Starter #169
From Tom Danley,

"Mike has taken the measurements according to the CEA 2010 criteria, like Illkka used except Mike measured at 2 meters for the values listed and we used a steady state sine wave instead of a tone burst..

These are steady state sine wave values (which is unavoidably harsh but we have not found an easy way yet to do it with a tone burst, with the test equipment we have.).
This is a pain in the rear too and we will re-visit this when we find an easier way to do it, but the weighted harmonic approach makes sense relative to perceptual masking..

So, anyway as of now, using a sine wave, one DTS-10 in half space, at two meters, reaches the following levels;
CEA 2010 Max RMS Output @ 2mtrs.
12Hz 102dB
16Hz 108dB
20Hz 109dB
25Hz 111dB
31.5 114dB
40Hz 114dB
50Hz 117dB
63Hz 115dB
80Hz 127 dB
Ultra low AVG 20-31.5Hz
111.3dB
Low Bass 40-63Hz
114.3
20Hz-80Hz AVG
115dB
I am keen to see how different two are, with our other Tapped horns there is a large improvement in the curve when you have two vs one.
Initially I had thought it would take two in a dedicated room, or four in a large room to reach the right fear factor.
When we can we will measure a pair the same way in half space, this will be significantly higher and produce a flatter response curve too..
Anyway, for those who were waiting for some comparable numbers, here are some to start with.
Best and happy listening.
Tom Danley"



There has been a considerable amount of speculation about these results as they are not nearly as high as expected in the range between 20 and 63hz. One thing to note is that it appears that the drivers got damaged during the tests because DSL used sine waves and cooked the coils. Illka's tests used a 6.5cycle short burst, which does not heat the vc's nearly as much and cause thermal compression as bad. There is speculation as to how much power was used as well, but it must have been significant and of long duration to have cooked the pair of drivers coils. Apparently the sinewaves were often on for more than 30secs to get the distortion reading. DSL is going to get a set-up for burst testing more comparable to Illka's and repeat the test to see how that affects the results. One thing that i can tell you is that the #'s measured don't seem representative of what I am experiencing with mine compared to 2 sub systems that I own that are basically the same as his #2 and #3 all time output champs. (sealed LMS and dual 15" SDX). Further investigation needed.


I've went back to looking at Illka's tests again for the billionth time and I noticed something which may, or may not be of interest. The top 4 subs that he tested for CEA2010 output 20-80hz average were the 2 different LMS 18 based diy, the dual SDX15 diy, and I believe the SVS PB13 Ultra. Here is what struck me as curious. If you look at the maximum output graphs before serious compression sets in it is significantly lower than the CEA2010 THD limited output using a 6.5 cycle burst for all 4 of the top systems and I'm sure many others too. The maximum output is using a very long 30sec sine wave sweep, while the distortion tests are a short burst. The distortion limited output is significantly higher than the long term maximum output. Note that he also has distortion plotted for the maximum output sweeps and it exceeds the CEA2010 allowable levels in many cases at the much lower volumes. See where I'm going here?

It seems like you could make a case that a short duration burst can indeed net quite a few extra DB before distortion gets out of hand as compared to a long duration sine wave.

I also noted a few other things like the fact that the PR LMS system's low end actually expands during the compression sweeps. You put 5 db in and get 6db out. I don't doubt that he measured that as I've seen something similar myself before. I never really bothered to think about the cause though. Anybody?
 

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I am thinking that the numbers are off. If they are running single frequency sine wave measurments and turning up till distortion sets in by the time they get to a higher level there may have already been damage. To me it SEEMS that they started with the 80 hz tone then went down in frequency repeating every time. There is a 12 db drop from 80 to 63 hz and if I recall that's at least 2 db more than what he got on the freq response graph. I believe when the tests are duplicated to illka standards will will see a whole new ball game.
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Discussion Starter #171
I'm thinking the same thing because it just doesn't jive with what people are hearing. We will see.

How's your kit doing BTW. Did you put some damping in there?
 

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Discussion Starter #172
Yesterday I tried to mix the DTS10 with a pair of sealed subs and I couldn't get them to play nice enough to use them together. I had a big V shaped cancellation between 18-23hz and even though I could get it to move around by adjusting the relative phases I couldn't get it eliminated enough to work for me. YMMV. Other people seem to be pulling it off.
 

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I'm thinking the same thing because it just doesn't jive with what people are hearing. We will see.

How's your kit doing BTW. Did you put some damping in there?
Damping is on my list. All I have for damping is what was provided though and I don't think that has very much of an effect at all. Where did you get your egg crate foam and how much was it?
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Discussion Starter #174
All of mine was free. It's just laying around at one of my buddies jobs and he gets good amounts of it free.
 

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I thought out of polarity was the same as out of phase? Am I having a senior moment?:huh:
Phase and polarity are not the same thing-but are very often confused with each other.

Phase dictates a freq and a time component. Polarity does not.

Two loudspeakers could be IN polarity and out of phase at the same time. It depends on the freq and spot/time on the "phase curve" involved.

If they are in or out of polarity-they are so at all freq.

You can check polarity with a battery-but you have to measure phase with a measurement system-since a battery is DC and has no "frequency".

I am a proud member of the "phase police".
 

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Excellent thread.
Wish I had the space. WAF is way to low for this to work for me! (Getting my 18" mal x in was an achievement!)
A question from an outside observer: Why did these take so long to gain such huge (almost viral?) popularity? If you look at threads from a few years ago, horn loaded subs were WAY in the background. It really is not a new technology, just took till now to gain a foothold and kick butt.
 

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Excellent thread.
Wish I had the space. WAF is way to low for this to work for me! (Getting my 18" mal x in was an achievement!)
A question from an outside observer: Why did these take so long to gain such huge (almost viral?) popularity? If you look at threads from a few years ago, horn loaded subs were WAY in the background. It really is not a new technology, just took till now to gain a foothold and kick butt.
I believe it is because this is the first time a kit has been offered at a price point that is available to more people.
 

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Excellent thread.
Wish I had the space. WAF is way to low for this to work for me! (Getting my 18" mal x in was an achievement!)
A question from an outside observer: Why did these take so long to gain such huge (almost viral?) popularity? If you look at threads from a few years ago, horn loaded subs were WAY in the background. It really is not a new technology, just took till now to gain a foothold and kick butt.
The reason horns have not been more popular for home use is that untill recently the only way to get "moderate bass" (30hz for example was to have HUGE horns that would not fit into normal rooms.

With the advent of the Tapped horn-we are now able to get deep bass in a "not so big" enclosure. At least as compared to years past.

One of the biggest advantages the Tapped horn offers over regular horns is the ability to get smooth low freq with a small mouth area. Normal horns require large mouth areas to get low and smooth.

There have also been lots of horns that are not built/designed properly and sound bad.
 
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