Collaborative Tapped horn project - Page 29 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th April 2007, 07:12 PM   #281
MaVo is offline MaVo  Germany
diyAudio Member
 
Join Date: Jan 2006
Quote:
Originally posted by freddi
I must have messed it up - got "system kywoord" error and cursor dropped to

Driver 'D1' Node=2=0=100=101 Def='Lab12'
If you make a new script, the only thing written in it is

System 'S1'

I forgot to mention, you have to copy my script and paste it <<after>> the words System 'S1' in the new script. If you delete those words or paste my script before them, it wont work.

You could also change the frequency values in the F5 menu to something like 10-500 to skip the not so interesting high frequencies.
  Reply With Quote
Old 29th April 2007, 08:09 PM   #282
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
thanks - that does look interesting - how do you think it compares to the other models?

http://img66.imageshack.us/img66/6193/thwg1ok3.gif
  Reply With Quote
Old 29th April 2007, 08:39 PM   #283
diyAudio Member
 
Join Date: Mar 2006
Location: Home
Well I will have to say the sound quality at the moment varies with spl and frequency, as I didn't brace the cab internaly as agressively as I should have but the spl performance should be close to what was graphed but it buzzes in some spots.

As far as, My listening and measuring seem to confirm that there is a bit more 2nd harmonic distortion (subjectively not objectionable sounding) around 20dB down, 3rd Harmonic distortion apears to be stupid low I think I measured something like 40 or 50dB down.

It definately sounds the best between 21-60Hz. The prototype makes a little noise in the 60-70Hz range which is due to lack of bracing. Its hard for me to judge the full qualilty of the sound as It is currently in a warehouse full of tools and shelves of things that rattle and buzz. And the little blue sky moitor speakers that I have are up stairs in a loft to monitor some of my source material.

From up there the quality of the LF is pretty nice, I can feel every LF tone through the loft, and most of the buzzning and rattling can't be heard.

From my own observation, I think my BS-212's that I built (A pair of 12cu' cabs housing 2 lab 12's each mounted push pull) Have much lower 2nd harmonic distortion, which makes some of the 20-30Hz tones seem more transparent. And I can get more clean SPL out of them at 20Hz (until vent velocity gets to high) than I can out of this TH prototype.

Mind you the pair of BS-212's can't do what the TH can do SPL wise from 22Hz on up without at least 2kW. The TH has an 800watt driver in it now.

Also I think my sealed quad lab 12 sub did pretty good down to and bellow 20Hz with lots of EQ, quite a lot of impact but can't compete with either the BS-212 or TH for SPL until about 50Hz.

I won't give a conclusion on over all sound quality until I get it well alligned and balanced with some full range boxes. Listening to the sub by it self doesn't really give any clear indication of SQ other than I didn't brace it good enough. Though I probably wouldn't ever need to use it that loud in a home environment so its not a total loss as a prototype.

I susspect that people will find it more "Musical" than a speaker with less 2nd harmonic distortion, and It does hit pretty hard probably due to the boost in sensitivity in the 70's.

I'm excited I have enough head room available that I can develop some sort of equal loudness curve EQ for the bottom end.

I like it, I think it would be great in almost any audio application that the space is available in.

Though my experience in small houses with lots of sub bass is, dishes rattling and studs vibrating apear louder than some of the low fundamental tones that are causing the disturbance.

Anyhow-

I give it thumbs up. I just want to push that knee down a bit more. I like to hit my 20 with authority.

Antone-
  Reply With Quote
Old 29th April 2007, 09:15 PM   #284
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
hi Antone - was the high H2 due to the driver? what power levels produced that high of 2nd harmonic? That might make it too "phat" -- H2 30 or more dB down would be much better.

(btw -MaVo's LAB12 TH script with DIYMA12 looks poor - I'd like to see his schematic vs enclosure sketch for the simplified script)

DIYMA in same enclouse - I think
http://img47.imageshack.us/img47/502...diyma12kq7.gif

Freddy
  Reply With Quote
Old 29th April 2007, 11:57 PM   #285
diyAudio Member
 
Join Date: Mar 2006
Location: Home
I recomend changing your view window.

I don't think you want to be concerned with much above 100-160Hz

1Khz is a little far out of the subwoofer passband

Antone
  Reply With Quote
Old 30th April 2007, 02:47 PM   #286
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
yeah - that's a bit optimistic too.

ya know, regarding high H2, can't find graph yet, but according to an old post my 11.2 cubic foot Yorkville UCS1 pipehorn at 20vrms & 50Hz had 10dB higher H2 than a 103g mms Eminence 18" with qt=0.26 in an 8 cubic foot Karlson box. AT 50Hz the K had a bit more ouput for same voltage drive. (UCS1's input Z was higher)

at 34Hz and small signal neither box is usable--the pipehorn had 15dB higher H3. It sounds "phat" and I won't use it. A vented box could be cleaner at home levels. Edgar's monolith with Dayton 295-070 is fairly clean to its nominal 40Hz cutoff. The Karlson seems to damp cone motion.

did you measure H2 outdoors?

Freddy
  Reply With Quote
Old 30th April 2007, 05:08 PM   #287
MaVo is offline MaVo  Germany
diyAudio Member
 
Join Date: Jan 2006
I included two 90 degree bends in the model and cleared it up a bit. To use it, copy it in an new akabak script after the System 'S1' line. Since the manual isnt very usefull concerning the accoustic mass, i am rather guessing what could be right. But then again, changing the acoustic mass only changes the high frequency response shape and the overall efficiency of the box. The model represents the geometry of the TH made by for example William Cowan. Tapping the driver into the horn is not supported (for this, use my first model posted some pages earlier)
You can play with the input data in Def_Const or the Def_Driver data.

Def_Driver 'Lab12'
dD=25.2cm |Piston
fs=33Hz Mms=146g Qms=13.32
Bl=15Tm Re=4.29ohm Le=1.48mH ExpoLe=0.618

Def_Const | all sizes in centimeters
{
| Input Data
DriverSize = 26e-2; | The outer driver diameter
Hornlength = 400e-2; | The overall length of the horn including the ducts around the driver
Box_z = 32e-2; | The depth of the box (z is constant - x & y get bigger from throat to mouth)
Throat_x = 10e-2; | Throat Area = Box_z * Throat_x
Mouth_x = 30e-2; | Mouth Area = Box_z * Mouth_x
| Experimental Data
Mass = 1.85/(Throat_x+((Mouth_x-Throat_x)/2));
Mass2 = 1.85/Box_z; | I dont know which dimension fits the accoustic mass of the bend. One can try both, "Mass" will be used in the calculation, "Mass2" will be ignored.
}
| Horn Modell
System 'Tapped Horn'
Driver 'D' Node=2=0=100=105 Def='Lab12'
Duct 'D1' Node=100 WD={Throat_x} HD={Box_z} Len={Driversize/2}
Duct 'D2' Node=100=101 WD={Throat_x} HD={Box_z} Len={Driversize/2}
Waveguide 'W1' Node=101=102 WTh={Throat_x} HTh={Box_z} WMo={Throat_x+((Mouth_x-Throat_x)/2)} HMo={Box_z} Len={(Hornlength/2)-DriverSize} Conical
AcouMass 'Bend1' Node=102=103 Ma={Mass}
AcouMass 'Bend2' Node=103=104 Ma={Mass}
Waveguide 'W2' Node=104=105 WTh={Throat_x+((Mouth_x-Throat_x)/2)} HTh={Box_z} WMo={Mouth_x} HMo={Box_z} Len={(Hornlength/2)-DriverSize} Conical
Duct 'D3' Node=105=106 WD={Mouth_x} HD={Box_z} Len={DriverSize}
Radiator 'Rad1' Node=106 WD={Mouth_x} HD={Box_z}
  Reply With Quote
Old 30th April 2007, 05:11 PM   #288
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
re: new model - maybe Cowan would run a mathcad to compare and help pick how much complexity on akabak is really needed to do 20-200Hz?

re: distortion - found the graph - ucs1 pipehorn had >20dB worse H2 than my smaller and lighther karlson with 18" at 20vrms/50Hz

20vrms-50Hz commercial pipehorn vs Karlson
http://img80.imageshack.us/img80/862...1820v50yg5.jpg

would the waveguide model work for these mutual load cases?
Click the image to open in full size.
  Reply With Quote
Old 30th April 2007, 07:00 PM   #289
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
hey MaVo - I forgot to ask - how close do your last two models come to Cowan's 30Hz tapped horn measured results with Peerless 830500 and 830515? (under what conditions did William make those graphs? - outdoors?)

Freddy
  Reply With Quote
Old 30th April 2007, 07:24 PM   #290
diyAudio Member
 
Join Date: Mar 2006
Location: Home
Fredii H2 was measured from in almost inside of the mouth of the TH.

I can post it if you wish to see it.


Mavo
Accoustic mass can cause most significant changes especially if its a large equivalent accoustic mass caused by a sudden expansion or contraction, it should lower tuning.

Antone-
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 03:00 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2