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Old 20th February 2012, 03:08 PM   #71
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Yep...Adding lining or stuffing can dramatically cut efficiency if too much is used. For Pro audio or high output cabs, heavy use is a no go. Some amount used minimally can also make a large improvement in cleaning up cabinet resonances though. IMHO this is the best use of it. Large cabs always have resonances in the bass range due to the long dimensions involved and they can ring or honk and color the sound in a noticeable and bad way. A moderate amount of damping or stuffing can make a big improvement cleaning these up with only a very modest sacrifice in efficiency. Unfortunately really the only way to determine the right amount to use is through measurements and trial and error.

As usual YMMV.
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Old 20th February 2012, 03:46 PM   #72
tb46 is offline tb46  United States
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Hi,

"...the only way to determine the right amount to use is through measurements and trial and error."

That's why it is so important to get the removable access panels right.

Regards,
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Old 20th February 2012, 05:42 PM   #73
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Quote:
Originally Posted by tb46 View Post
Hi,

Yes, you are correct (5.680" [14.4cm]). I'll change the location of the dimension in the drawing.

Regards,
Ok I will glue the other end at 5.68in (interior) later on this afternoon
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Old 20th February 2012, 05:45 PM   #74
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Quote:
Originally Posted by tb46 View Post
Hi,

"...the only way to determine the right amount to use is through measurements and trial and error."

That's why it is so important to get the removable access panels right.

Regards,
I cut access panels on both sides of the box yesterday. I got a new rabbit bit for the router so I could make 1/2 inch lips.

Any recommendations on a mic that I can use for tuning the flattest response? Is this one a decent one to get? Dayton Audio OmniMic Precision Measurement System 390-790 I will use it for tuning everything, not just bass.
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Old 20th February 2012, 06:04 PM   #75
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Originally Posted by 2MuchRiceMakesMeSick View Post
Any recommendations on a mic that I can use for tuning the flattest response? Is this one a decent one to get? Dayton Audio OmniMic Precision Measurement System 390-790 I will use it for tuning everything, not just bass.
Looks like a decent system for a fair price, and the calibration availability is a great thing.
There are far cheaper mics available, but without calibration you don't really know if the mic is accurate- I spent weeks of frustration thinking my designs were anemic, only to find the mic response (on a $1500 test set ) was rolled off in the bottom end, 6 dB down at 35 Hz, 10 dB down at 20 Hz..

You would not have that problem with the above system.

Art
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Old 20th February 2012, 08:56 PM   #76
bjorno is offline bjorno  Sweden
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Thumbs down EQ instead of properly damping a Quarter-Wave design for home use?

Quote:
Originally Posted by 2MuchRiceMakesMeSick View Post
My entire system uses active xover and equal at the preamp level if that helps any.
Why adding a chain of electronics that do more harm than enhancing the SQ already built in:

You are ...not... designing a traditional TL that MJK:s pictures depict,i.e. almost completely stuffed to allow a use up until a kHz.

You are designing a T-TQWT sub that needs to be stuffed as previously suggested for home use and not a second should for this purpose should SPL be traded from a smooth BW(IMO).

Damping(The Main delayed Pulse) should always be applied where the place of origin is(are) in a quarter-wave design like this is.

The Pre-Pulse that is that is added to the Main-Pulse has almost a near blameless FR,needs no damping or EQ at all.

Tweak one and the other will suffer with almost reciprocal FR dips and peaks as they are separated in time..

IMO your T-TQWT will have blameless FR errors in the pass-band but if your room play havoc with the stationary FR I recommend you to use more subs i.e. no EQ:s at all.

Follow TB46 advises instead...+ just use an ordinary (plate) amp with built in HPF and LPF and you are all set...

b
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Old 21st February 2012, 03:12 PM   #77
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Hello, I have two questions this morning.

First question is, The center board (baffle?) is about 0.70 inches too short. The way this came about is I put a full 19 x 12.56 for the board that has the mouth/terminus. I will route the mouth with a follower bit for a perfect cut. The reason for this is because I did like the three inch gaps on each side, not a big deal and its easily fixed
The problem is, when I went to make the baffle 0.70 shorter I took it from the opposite end of the speaker.

The way it sits in the box the board is the correct size. What is not right the woofer holes are not all the way up against the corner. Instead they are 0.70" from the corner of the box.

Im not one to half way to anything and if this will affect the sound, i will gladly cut a new board to make it EXACT. I have not glued this board and whatever you decide will be done across all 4 boxes. Its easy to fix now.

So will this affect the sound?

Last edited by 2MuchRiceMakesMeSick; 21st February 2012 at 03:15 PM.
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Old 21st February 2012, 03:24 PM   #78
tb46 is offline tb46  United States
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Hi 2MuchRiceMakesMeSick,

"...the woofer holes are not all the way up against the corner. Instead they are 0.70" from the corner of the box."

I'm not sure that I get what you mean, there is a 0.742" gap between the frame of the woofer and S1 in the drawing. Moving the drivers 0.7" closer to the mouth-or further away-should not make an audible difference.

Regards,
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Old 21st February 2012, 03:27 PM   #79
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Quote:
Originally Posted by tb46 View Post
Hi 2MuchRiceMakesMeSick,

"...the woofer holes are not all the way up against the corner. Instead they are 0.70" from the corner of the box."

I'm not sure that I get what you mean, there is a 0.742" gap between the frame of the woofer and S1 in the drawing. Moving the drivers 0.7" closer to the mouth-or further away-should not make an audible difference.

Regards,
I'd agree, sounds like a filler piece should be glued in and some sealant applied and no one but us will know the difference.
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Old 21st February 2012, 03:40 PM   #80
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Please excuse my drawings, I am not an artist.

Your drawing called for this arrangement.

Click the image to open in full size.


Instead my baffle looks like this.
Click the image to open in full size.


When I went to make the side board (terminus) and made it all one peice I had to shorten it one board length so it maintained the 57.403 measurement. Instead of cutting the red from the board, i cut the green which moved the woofers 0.7 inches closer to the fold
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