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Old 26th May 2011, 08:13 PM   #21
DrDyna is offline DrDyna  United States
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Or this one with a window O_O
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Old 26th May 2011, 09:47 PM   #22
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Hi,

Great pictures, looks good,you really got it right now!

I have only glued square frames of 3/4" x 1" of hardwood(Oak) to mount a frontally placed access lid on, never tested a side lid or rear for a T_TQWT due to the possibility for air leaks as the pressure is high immediately behind the drivers.

b
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Old 27th May 2011, 12:17 PM   #23
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by bjorno View Post
Hi,

Great pictures, looks good,you really got it right now!

I have only glued square frames of 3/4" x 1" of hardwood(Oak) to mount a frontally placed access lid on, never tested a side lid or rear for a T_TQWT due to the possibility for air leaks as the pressure is high immediately behind the drivers.

b
Yeah, I've discussed it with she who must be obeyed and it seems the general consensus is we prefer the ones that don't have a window, and in the end, I'll probably beef up that area around the access door in the front to more than 1cm of lip. I may just double-layer the front.

Thank you for all your help! I just wish you were closer by so you could come by and have a beer when I get them done and give them a listen!
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Old 29th May 2011, 12:41 PM   #24
DrDyna is offline DrDyna  United States
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I've grabbed some 3/4 Birch ply and it seems to be of decent quality. It's pretty solid compared to the MDF that I'm used to working with and it looks nice enough to stain. I'll post some pictures up once I get a chance to make a few more cuts later this afternoon.

One big thing that I'm curious about is stuffing. In your opinion, do you think polyfill would work? How far up the tube should I try to use it?

I've heard a few people say "stuff to taste". I think I might leave one side unglued temporarily so I can experiment with different stuffing or fiberglass lining. What do you think?
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Old 30th May 2011, 12:21 PM   #25
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Quote:
Originally Posted by DrDyna View Post
I've grabbed some 3/4 Birch ply and it seems to be of decent quality. It's pretty solid compared to the MDF that I'm used to working with and it looks nice enough to stain. I'll post some pictures up once I get a chance to make a few more cuts later this afternoon.

One big thing that I'm curious about is stuffing. In your opinion, do you think polyfill would work? How far up the tube should I try to use it?

I've heard a few people say "stuff to taste". I think I might leave one side unglued temporarily so I can experiment with different stuffing or fiberglass lining. What do you think?
Hi,

Polyfill should work or any longhair polyester fiber: See the links here-below, though you should start filling you box with ~ recommended average density and weight.

'Stuff to taste' is not reliable unless checked with real measurements.(See the first MJK simulation(1.511 lb/ 0.5 lb/ft^3)

Essentially you want to use a material with a linear absorption factor versus frequency.

You can also partly fill the enclosure, IME the best method to stuff an TH (compression ratios at or below 3:1) and instead of using itching fiberglass:

See the Technicon acoustics links where block-strips can be cut and inserted with ~2-3” air spaces between each block to form a path that isn't entirely filled but lets the air easily flow through.

Hints and reading:

http://documents.jordan-usa.com/Famo...mped-Pipes.pdf

Damping material - big differences in poly fill types

Suitable Polyester fiber:

Acoustic Wadding Material | LS00385 | Distributed By MCM

Polyester fiber in
Tech Bulletins | Technicon Acoustics - Technicon Acoustics


2" thick polyester fiber:
http://www.techniconacoustics.com/si...2-80-00-00.pdf

Added a few new simulations showing the effect of using damping material in a T-TQWT . The passband FR is as for the earlier HR plots but above ~80 Hz the MJK simulations are more reliable and shows the impact on off-band FR and the resulting superior IR that comes with introducing damping material in the air path,IMO: always necessary for any Hi-Fi quality speaker.

b

Last edited by bjorno; 30th May 2011 at 12:26 PM.
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Old 31st May 2011, 01:13 PM   #26
DrDyna is offline DrDyna  United States
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Awesome. I'll check out all of this and make some adjustments over the next few days. For the moment, they have a small amount of stuffing in the chamber behind the drivers that goes about 1/4th of the way up, and they seem to sound very good right now, but I'm sure it can only get better!

When I first brought them upstairs, I placed them next to my main speakers out in the middle of the room. It seemed that the response rolled off very sharply after about 40hz. It was quite funny. I think the first thing I said was "F---, these are tuned low!" Tracks like "Grandaddy - He's Simple, He's Dumb, He's The Pilot" had almost no bass at all except for the lowest 2 notes.

After a little moving around, I settled on them near the corners, with the mouth facing out. They are very pleasant in this position. The response seems wonderful all the way up to my crossover point 80hz @ 12db.

I'm very pleased already and I'm sure I'll be even more happy with them once I get the stuffing correct.
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Old 4th June 2011, 03:16 PM   #27
DrDyna is offline DrDyna  United States
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After a few days of listening and trying various amounts of acousta-stuff, I've settled on a fairly light stuff that goes about 30-40% of the way up from behind the drivers to a little past the first brace.

I am very much in love with this design. I can't thank you enough for all the help Bjorno, I had no idea these drivers had this level of smoothness and power in them.

Now I'm thinking about making another pair for the 2 singular drivers I have left that were in my corner loaders!

You've created a monster!
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Old 27th June 2011, 07:16 PM   #28
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Bjorno, if you're still tracking this thread, I've come up with a couple of additional questions if you have a minute

Now that I've had a chance to live with these for a little while and today I have some spare time again where I can do some moving around and tweaking, I've noticed that they seem to sound the best firmly wedged in the corner, placed on a thin piece of wood. I've tried them higher (with the mouth almost at ear level) and at various placed in between, but it seems like this is the position that I'm happy with, as they seem the most efficient.

Could you confirm that this is the ideal placement? I don't have a measurement microphone yet (I'm planning on getting an inexpensive one in the future) but I just want to pick your brain on placement.

Lastly, what effect, if any, would there be if I put a chamfer on the front of the mouth with a round-over bit?

Pictures are their current positions, corners left and right with the wood base.
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Old 15th July 2011, 07:34 PM   #29
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by DrDyna View Post
Bjorno, if you're still tracking this thread, I've come up with a couple of additional questions if you have a minute

Now that I've had a chance to live with these for a little while and today I have some spare time again where I can do some moving around and tweaking, I've noticed that they seem to sound the best firmly wedged in the corner, placed on a thin piece of wood. I've tried them higher (with the mouth almost at ear level) and at various placed in between, but it seems like this is the position that I'm happy with, as they seem the most efficient.

Could you confirm that this is the ideal placement? I don't have a measurement microphone yet (I'm planning on getting an inexpensive one in the future) but I just want to pick your brain on placement.

Lastly, what effect, if any, would there be if I put a chamfer on the front of the mouth with a round-over bit?

Pictures are their current positions, corners left and right with the wood base.
Hi DrDyna,

Thank you for posting pictures of your now two subs?

I would too agree that a corner placement is near ideal for a T-TQWT at least if used as a main sub operating below 80 Hz /12 dB HPF filter.

I always chamfer my ports if the port is smaller than a third of Sd but if wider, I find no reason to do as the port acoustic mass in operation is confined in a much larger volume,i.e, the volume of internal and external correction factors lengths result in a much larger volume compared to the wood thickness times the port diameter.

Smoothing/chamfering a small radius using a medium coarse is IMO enough.

Submitting a new simulation using only one driver:

b
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Old 15th July 2011, 08:05 PM   #30
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by bjorno View Post
Hi DrDyna,

Thank you for posting pictures of your now two subs?
Yeah, I was always planning to make 2, one is left one is right For clarity, I have 2 drivers in each one of the tubes and I have 2 more to use up, so I have a total of 6...well, 7 if you count the one that's in my center channel sub, but I'm happy with that one

Quote:
I would too agree that a corner placement is near ideal for a T-TQWT at least if used as a main sub operating below 80 Hz /12 dB HPF filter.
Awesome. I just wanted to make sure that what I was hearing was correct and I didn't have some room effect happening. They are indeed crossed over around 80hz @12db. My hpf is a single series cap for the mains.

Quote:
I always chamfer my ports if the port is smaller than a third of Sd but if wider, I find no reason to do as the port acoustic mass in operation is confined in a much larger volume,i.e, the volume of internal and external correction factors lengths result in a much larger volume compared to the wood thickness times the port diameter.

Smoothing/chamfering a small radius using a medium coarse is IMO enough.
For me, it's purely aesthetic. I was thinking that if I rounded the edges it might make the port look bigger! If there is no ill effect, I'll give it a try.
Quote:
Submitting a new simulation using only one driver:

b
Thank you very much!
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