Can someone comment on my hornresp simulations on the MCM8? - Page 3 - diyAudio
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Old 11th December 2010, 02:26 PM   #21
JLH is offline JLH  United States
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You can't easily use a passive crossover with a tapped horn. I've gone around and around with this using Akabak software. Unlike Hornresponse, Akabak has a means to simulate passive crossover components. The passive components mess up the electro-mechanical tuning of the tapped horn. The best route is to use an active crossover in front of the amplifier.

In addition, the T/S parameters for the MCM 8" are all over the place. They also change quite a bit after break-in. The suspension gets sloppy on these, so Cms changes a lot. To save you some trouble, give those MCM 8's a good break-in period and then measure the T/S parameters yourself. This will give your project the best chance for success.
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Old 11th December 2010, 03:25 PM   #22
jbell is offline jbell  United States
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Originally Posted by JLH View Post
In addition, the T/S parameters for the MCM 8" are all over the place. They also change quite a bit after break-in. The suspension gets sloppy on these, so Cms changes a lot.
I second that motion... been there, done that. The best place for a MCM is a small sealed in car, or in a front loaded horn for PA with a very small sealed rear chamber. The small rear chamber helps control excursion, and consequently helps preserve the spider.

You want something that can hit 120db in car, you kinda need a 'car pa' style for your mcm's. In other words -- a PA FLH style cab with a sloping response, so in car it's flat.

my 2c.
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File Type: jpg 55-2421flh-car.JPG (59.4 KB, 108 views)
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Old 11th December 2010, 08:25 PM   #23
Mark Kravchenko --- www.kravchenko-audio.com
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Bern you have the attention of all the big guns, jbell, JLH and even tb46. How do you do it?

Mark
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Old 12th December 2010, 05:59 PM   #24
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ok cool, so eq works just the same way as with sealed boxes. And when I add a coil, I'd also have to add the resistance.

Now that brings me to wonder, if I was to use a passive high pass filter - as with most of these bass horns a HP is needed - at say, 30Hz, would the caps and coils do anything unexpected to the response? Or would it just apply the designed high pass effect just the same way as it would if used on a sealed box?

That might be a stupid question with a simple answer, but I have to ask, since horns are sooooo different than a sealed box, and I have never used a horn before.
I have measured the effect of a series inductor on a Tang Band W6-1139 tapped horn. It does not behave exactly like a passive crossover per se.

The effect was nearly exactly what the model shows us, the peaks in the passband that correspond to the excursion minimas were damped somewhat, the saddle (excursion maxima) remained unchanged, except for the attenuation due to the additional series resistance.

You only need a single inductor, wire it in series with the drivers. As far as a high-pass, active is a much better idea, the coils and caps involved get rather unwieldy and extremely expensive if you want to have a slope that might actually protect your driver at the end of the day.

Last edited by littlemike; 12th December 2010 at 06:02 PM.
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Old 12th December 2010, 06:00 PM   #25
Mark Kravchenko --- www.kravchenko-audio.com
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dang forgot littleMike.

You are probably 6'2" 240lbs Mike!

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Old 12th December 2010, 06:09 PM   #26
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dang forgot littleMike.

You are probably 6'2" 240lbs Mike!

Mark
Close....6'1". You nailed the 240 part though....

While we're about the same size, Big Mike is a retired Marine. No one there was gonna call him "Old Mike", so he got "Big Mike". I got "Little Mike". My bosses are really creative when it comes to nicknames.

Problem is - we hired another Mike a while back....and he's littler than me - so what do we call him???
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Old 12th December 2010, 06:14 PM   #27
Mark Kravchenko --- www.kravchenko-audio.com
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LOL

I was once in a class in high school where there were 4 Mark's. I was Gus!

I'm close 6', 206lbs lost a whack load since the spring. Never looked back since. Was 238. Happy at 206!

Do you have any actual measurements for the MCM 8" drivers? I would love to simulate using the correct specs. I might get me a bunch of them.

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Old 12th December 2010, 06:57 PM   #28
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Here's what I measured when I did the HornResp Tapped Horn tutorial example build. It has been a little while since I measured these, but they are similar to what I have measured in the past.
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File Type: pdf 55-2421 specs.pdf (19.4 KB, 21 views)
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Old 12th December 2010, 06:59 PM   #29
Mark Kravchenko --- www.kravchenko-audio.com
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Thank's Mike. Muchly appreciated.

Inside today with a bad cold. I'm supposed to be building some tapped horns and FLH subs!

Oh well.

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Old 14th December 2010, 03:59 AM   #30
blamus is offline blamus  United States
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Default TS

Here's my effort - this is before break in.

How do they look?


1

* This data was exported from the Dayton Audio WT3 Woofer Tester
*
* Manufacturer:
* Model:
* Piston Diameter = 161.9 mm
* f(s)= 28.94 Hz
* R(e)= 3.38 Ohms
* Z(max)= 193.70 Ohms
* Q(ms)= 12.370
* Q(es)= 0.219
* Q(ts)= 0.216
* V(as)= 31.240 liters (1.103 cubic feet)
* L(e)= 2.67 mH
* n(0)= 0.33 %
* SPL= 87.27 1W/1m
* M(ms)= 57.64 grams
* C(ms)= 0.52 mm/N
* BL= 12.70
*


2
* Manufacturer:
* Model:
* Piston Diameter = 161.9 mm
* f(s)= 28.94 Hz
* R(e)= 3.33 Ohms
* Z(max)= 179.30 Ohms
* Q(ms)= 11.480
* Q(es)= 0.217
* Q(ts)= 0.213
* V(as)= 31.400 liters (1.109 cubic feet)
* L(e)= 2.63 mH
* n(0)= 0.33 %
* SPL= 87.34 1W/1m
* M(ms)= 57.36 grams
* C(ms)= 0.53 mm/N
* BL= 12.64
*


3
* Manufacturer:
* Model:
* Piston Diameter = 161.9 mm
* f(s)= 29.61 Hz
* R(e)= 3.31 Ohms
* Z(max)= 187.10 Ohms
* Q(ms)= 12.500
* Q(es)= 0.225
* Q(ts)= 0.221
* V(as)= 32.240 liters (1.139 cubic feet)
* L(e)= 2.63 mH
* n(0)= 0.35 %
* SPL= 87.60 1W/1m
* M(ms)= 53.36 grams
* C(ms)= 0.54 mm/N
* BL= 12.08
*


4
Manufacturer:
* Model:
* Piston Diameter = 161.9 mm
* f(s)= 29.61 Hz
* R(e)= 3.32 Ohms
* Z(max)= 179.90 Ohms
* Q(ms)= 11.550
* Q(es)= 0.217
* Q(ts)= 0.213
* V(as)= 32.300 liters (1.141 cubic feet)
* L(e)= 2.59 mH
* n(0)= 0.37 %
* SPL= 87.76 1W/1m
* M(ms)= 53.25 grams
* C(ms)= 0.54 mm/N
* BL= 12.31
*
*
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