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Old 24th March 2010, 01:58 AM   #41
jwmbro is offline jwmbro  United States
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I made a real quick model in sketchup today. Would the following depict the correct way to build a T-TQWT?

Click the image to open in full size.
Click the image to open in full size.

The colored parts aren't depicting actual physical objects, but rather the areas/distances to be measured. Assuming the green area is S1, the blue area is S2, the purple area is S3 and the pink area is S4, the yellow length is L12, the orange length is L23 and the red distance is L34... is this the correct layout for such an enclosure?
The area between the divider and the left end of the enclosure needs to be exactly (S2+S3)/2 , right?

I'm definitely leaning towards building one or two of these, just to see how it works out, simply out of cheap 16 or 19mm MDF.

Meanwhile I'm still waiting on MCM, whose customer service, I must mention, has been very helpful so far.
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Old 24th March 2010, 04:35 AM   #42
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by klankymen View Post
I made a real quick model in sketchup today. Would the following depict the correct way to build a T-TQWT?

Click the image to open in full size.
Click the image to open in full size.

The colored parts aren't depicting actual physical objects, but rather the areas/distances to be measured. Assuming the green area is S1, the blue area is S2, the purple area is S3 and the pink area is S4, the yellow length is L12, the orange length is L23 and the red distance is L34... is this the correct layout for such an enclosure?
The area between the divider and the left end of the enclosure needs to be exactly (S2+S3)/2 , right?

I'm definitely leaning towards building one or two of these, just to see how it works out, simply out of cheap 16 or 19mm MDF.

Meanwhile I'm still waiting on MCM, whose customer service, I must mention, has been very helpful so far.
Hi Klankymen,

Your Sketchup drawings are really good and depict a T-TQWT in better ways than my oversimplified drawings I show here at diyAudio.

Your layouts are correct as far as I can see.

The only comment I have is: The top area of the box is = S2+S3)/2 + the area of the end of the divider, so for your case: The inner depth of the box should increase with 16 mm or 19 mm as you should compensate for the volume occupying by the divider.

b

Last edited by bjorno; 24th March 2010 at 04:38 AM.
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Old 14th April 2010, 02:31 PM   #43
jwmbro is offline jwmbro  United States
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Quick question: Is there any harm in running a subwoofer fullrange (apart from the crappy sound)?

I know that running a tweeter fullrange will damage it, but running a woofer fullrange? Apart from overexcursion below tuning obviously?
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Old 14th April 2010, 02:56 PM   #44
vadi is offline vadi  Austria
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I think your amp won't do it. You need a lot of power for a sub in higher frequencies. Hornresp tells you how much you need too.
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Old 14th April 2010, 04:07 PM   #45
jwmbro is offline jwmbro  United States
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but if I were trying to make a HOLM-Impulse measurement.... Could I just connect Soundcard --> Amp --> Woofer? Without using any lowpass in there, I mean. Will that damage anything?
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Old 14th April 2010, 04:33 PM   #46
vadi is offline vadi  Austria
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I'm no expert, I never measured a woofer but Idoubt you'll damage anything at low power (for measurement).
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Old 14th April 2010, 04:46 PM   #47
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You could band limit your measurement signal in HOLM. That way you don't have to hear the higher frequencies(shouldn't be too bad with a T-TQWT anyway). And you could set the highpass to limit excursion.
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Old 11th July 2010, 03:15 PM   #48
jwmbro is offline jwmbro  United States
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Slow progress going on here, I realize, but I have a minor question I'd like to ask.

I want to put 4 binding posts on each subwoofer, so that I can externally switch between series and parallel connections, without having to open up the whole box. While researching prices, I found that I can obtain one such terminal plate:

Click the image to open in full size.

for less money than the cost of a single pair of bindings posts:

Click the image to open in full size.

of which I would of course require two pairs to offer the same amount of connections as with the plates.

However, as I am currently leaning towards a sealed box design (instead of vented, as originally thought), I am somewhat worried by how good the seal from such a flimsy plastic construction would be.

Do you think I can use one of those plastic plates without worrying about airleaks, or am I better of sticking with the pricier individual binding posts?

The price difference for the whole project would amount to about 25 euros, which is not an insignificant amount (that's more expensive than one driver is!).
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Old 11th July 2010, 05:32 PM   #49
AndrewT is offline AndrewT  Scotland
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a 4pole Speakon would allow all the flexibility you need.
Each of the 4wires feeding the two drivers terminates in the socket.
You can drive them individually, or in parallel, or in series.
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Old 11th July 2010, 10:56 PM   #50
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by AndrewT View Post
a 4pole Speakon would allow all the flexibility you need.
Each of the 4wires feeding the two drivers terminates in the socket.
You can drive them individually, or in parallel, or in series.
But then I'd have to resolder the Speakon connector every time I wish to change something (or recrimp my wires). But the whole point of what I'm trying to do here is to be able to change the circuit layout on the fly, without unscrewing or resoldering anything.
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