My Dual Tang Band 8x12 Tapped Horn Project - Page 8 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #71 of 99 Old 04-07-10, 11:00 AM
Elite Shackster
 
Ricci's Avatar
Josh
 
Join Date: May 2007
Location: Louisville, KY
Posts: 2,431
Re: My Dual Tang Band 8x12 Tapped Horn Project

Quote:
mwmkravchenko wrote: View Post
Seven cubic feet bigger
Ouch


Mark
That's sort of what I was thinking. I'm not sure how the side panels and internal panels could take up an extra 7cu ft (200L)? Maybe it's bigger than 650L internal?

That is one big sub...
Ricci is offline  
Sponsored Links
Advertisement
 
post #72 of 99 Old 04-07-10, 11:31 AM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

Don't forget 852L is the external dimensions, using 3/4" plywood throughout, and the 650L figure is before any materials. I just double checked everything - the math all comes out the same. In fact, the mouth on the final product is actually measuring a bit smaller because I took some wood off the one panel to eliminate a gap.

The original design was only 609 liters, or around there. Decided to make it deeper just to ease up on the compression ratio, and because it made the most out of the wood I had on hand. Maybe I should have just left it alone

I am so glad right now it's still not so deep it can't fit behind the projector screen, and not so tall I can't get it out of the basement for painting on a future day. Also very glad I bought casters for it.
Oklahoma Wolf is offline  
post #73 of 99 Old 04-08-10, 09:52 PM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

After taking a day off to let my foot heal up and get some other stuff done, I went at it again today. As it stands right now, it's all over but the rumbling. The box is built, and will be ready for the woofers once the PL cures.

It didn't take long to finish off my initial can of PL - I got four of six braces installed with it. So frustrated was I with the CDX plywood I used for bracing, I decided not to install the side to side dowel bracing at all. Will have to see what effect that has, but this 3/4" shop birch is so stable I should be ok. Used the pocket screw idea to install the bracing - some of those screws didn't go where they were supposed to, and wouldn't come back out. So I PL'd over them... that'll show 'em.

The top panel was, as expected, the hardest part of the whole thing. I went nuts on the PL to insure all gaps were filled - I cut the spout on the new tube as far down as the gun would cut it. The tops of all the interior panels got so much of the stuff, the second tube is now almost empty. This resulted in making the top panel extra hard to line up, but I managed somehow. Used #10 screws to fasten the interior panels, and the rest of the #6's on the edges. No leaks that I can find.



This is when I had to stop to change PL tubes.



All bracing in, ready to start drilling the screw holes for the top panel. Measured very carefully to insure I was hitting the interior baffles in the middle for those #10's. Some didn't quite hit the middle, but they all found the baffles.



There is no bracing in the throat whatsoever - I wanted to keep compression ratio as low as possible. So, I PL'd and screwed in this mini brace on the other side of that panel.



The throat and the first two folds got a very thin layer of polyfill. The remaining folds have nothing.



All done. It took some doing to find the best alignment for the top panel, but I managed.

Thus concludes the most difficult subwoofer build I have ever attempted. I'm expecting this to rumble to life sometime on Saturday or Sunday - I want that PL cured before I fire it up.
Oklahoma Wolf is offline  
 
post #74 of 99 Old 04-09-10, 08:17 AM
Elite Shackster
 
Ricci's Avatar
Josh
 
Join Date: May 2007
Location: Louisville, KY
Posts: 2,431
Re: My Dual Tang Band 8x12 Tapped Horn Project

I'm glad I don't have to move that thing! That's one big horn.
Ricci is offline  
post #75 of 99 Old 04-09-10, 08:44 AM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

Heh - the decision to go get casters was made shortly after cutting the panels and realizing this thing was easily big enough to give me nightmares about moving it

It's still not too bad for weight - I can get one end off the ground one-handed. MDF would have given me serious problems I'm sure.

At one time I was considering handles for it - still not sure that was a bad idea.
Oklahoma Wolf is offline  
post #76 of 99 Old 04-09-10, 07:26 PM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

I couldn't wait any longer...



Got it all up and running now. Before I let you in on my initial impressions, some more pics for you.



Me and my pet monster just before caster and driver installation.



Some of the goodies I used for wiring. Had to solder the wire to the small terminals on the TB's - they used a different size for negative than positive. That duct seal is fun to play with - it's like sticky putty.



Wolfhorn II in its temporary new home pointing at the magic corner. Eventually, it will point at it from the other way, behind the screen.

Ok... listening impressions. I strapped the beast to channel 1 of the RMX-1850HD, hooked up the DMM, and went to town. First thing I did was calibrate it for reference according to the SPL meter and the Pioneer test tones. Left the Reckhorn B-2 at its IXL gain level, removed the boost I was using on it, and plugged in my 10Hz test tone.

Already, things got interesting. Anytime the Pioneer went above -10dB, the horn started belting out the harmonics. One moment I would hear nothing at all, and then whammo... everything is shaking. I go over to the sub, and the woofers are barely moving. I then set the B-2's SSF to allow no more than 5V at 10Hz to avoid having things come off the walls.

After that, I ran some 15-20Hz test tones through it. As expected, the corner is juuuust over 16Hz. Didn't get much chance to turn it up good yet, but I can tell already this is going to be fun to listen to.

So what did I do next? War of the Worlds. Street cracking scene. Maybe it's just me not fine tuning the SSF enough, but I was expecting it to outdo the IXL here. SPL meter says it didn't. I saw the amp voltage hit 38V during this scene... max safe voltage as modeled is supposedly 36V. However, I didn't go over to the sub to check on the woofers - I need to do that yet. If they're not approaching Xmax, I'm ok. Given that the SSF is probably set too high to allow this thing to really open up on me, I'm inclined to think I need to do some tweakin' yet.

All that being said, this thing was brutal during that scene. At -24dB on the receiver, it was already coming close to the IXL for SPL. I'll dial it in this evening and run MCACC once there's nobody in the house. Then I'll probably go back and forth between test tones and get the SSF squared away. Then I get to watch Sherlock Holmes.

BTW - the sound is cleaner than the IXL by a fair bit. Good golly - if this is what a homebrew tapped horn sounds like, a Danley must be phenominal.

I'll report back later once things are set up properly.
Oklahoma Wolf is offline  
post #77 of 99 Old 04-09-10, 08:01 PM
Senior Shackster
 
mwmkravchenko's Avatar
Mark
 
Join Date: Jul 2009
Location: Perth Ontario Canada
Posts: 580
Re: My Dual Tang Band 8x12 Tapped Horn Project

Glad to hear it's working Jeremy!

Mark

___________________________________________________________________________ ___________

Mark

Artificial intelligence is no match for natural stupidity.
mwmkravchenko is offline  
post #78 of 99 Old 04-09-10, 08:25 PM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

Things still aren't set up properly, but I have a few more observations. Ran some test tones in 5Hz steps between 20 and 90Hz. The bad news - the 50Hz dip is there. The good news - it's not much of a dip. The 70Hz peak isn't there at all, according to the SPL meter. The horn is surprisingly linear from there to 90Hz... I may have gotten lucky with the bandwidth of this thing.

Also lowered the SSF a bit and ran my DTS copy of The Haunting with the Pioneer at -25dB. At the scene just after Liam Neeson's character arrives, there's a scene with his assistant standing alone in the foyer. This scene has a nice blast of around 20Hz LFE in it. SPL meter hit 100dB at the mouth, 5V in. Wall paneling was already shaking. Drivers didn't even do 8mm of throw, if my eyeballs are right.

I bet the thing was well over 110dB at listening position when WotW was letting the amp put 38V through the sub. I was too busy worrying about the voltage to go check with the SPL meter... the amp is too far from LP to know for sure and that's where the DMM was... by the amp.

Incidentally - 3.25:1 compression ratio is fine for these woofers, it seems. No problems yet, anyway. I think there may be some loose brace or something buzzing in the horn somewhere, but I can't find any air leaks. Might be a loose PL Premium booger vibrating too. Not worried - it's not audible anywhere but right up by the mouth.
Oklahoma Wolf is offline  
post #79 of 99 Old 04-09-10, 09:07 PM Thread Starter
Senior Shackster
Jeremy
 
Join Date: Dec 2009
Location: Eastend, SK, Canada
Posts: 333
Re: My Dual Tang Band 8x12 Tapped Horn Project

OKAY - I am officially glad I built this

After MCACC, the LFE channel is set 3dB cooler than the IXL and 5dB cooler than I had it set. Same input level at the amp, same level at the Reckhorn. SSF seems to be ok bottomed out, but I'll run it at 14Hz for now until I know the sub better.

I re-ran the street cracking scene in WotW and really let 'er rip. Normal listening level of -17dB. This thing easily hit 120dB at the mouth, and the woofers did fine. They maybe hit 9mm of throw. Voltage never even got close to 38V. Sitting there next to it, it was literally shaking my insides.

Not sure I have the headroom I wanted, but it looks like I have my reference level playback at last. For a first time tapped horn build, I'm quite pleased. Maybe I should build another one to stack on top of it... I do have some room between it and the ceiling...
Oklahoma Wolf is offline  
post #80 of 99 Old 04-09-10, 09:12 PM
Senior Shackster
 
mwmkravchenko's Avatar
Mark
 
Join Date: Jul 2009
Location: Perth Ontario Canada
Posts: 580
Re: My Dual Tang Band 8x12 Tapped Horn Project

Quote:
Maybe I should build another one to stack on top of it... I do have some room between it and the ceiling...
Maybe a little to much shaking????

Well what you actually got is a Taped Tapered Quarter Wavelength Resonator. They work well as you have found out. But a true tapped horn it is not. They are evily difficult to make and can be done with only a small handful of drivers.

But nit picking aside you are having fun right?

Hey do you have a peak hold on your meter? Or are you already using that function to measure the peak input voltage?

Mark

___________________________________________________________________________ ___________

Mark

Artificial intelligence is no match for natural stupidity.
mwmkravchenko is offline  
Reply

Bookmarks

Tags
8x12 , band , dual , horn , project , tang , tapped

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may 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 is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome