midrand enclouse design, help?

[Mike E]

I am playing with this online box calculator for sealed boxes. the driver im looking at and messing with in this box calculator has a FS or 160. according to it with a .707 QTC the F3 is 435hz. i know i should be using winisd but i didnt want to enter in all that info yet. since im still unsure if i want to buy the driver and mess with it.

The idea was to go with min parts in the XO for the TB W2-748SG. If i use the QTC .707 and use the suggested .001cuft box with a F3 of 435hz. im tring to figure out how to use a first order XO with the boxes natural roll off to make a 2nd order xo. the other option i came up with was a QTC .584 making the VB .002cu ft with a F3 450hz. the problem is a QTC of .54 thru .65 yeild the same VB but different F3. if i want a target F3 of 450hz to use in same region with the xo how would it be possible. maybe i need to switch to winisd to see what happens.

any thoughts guys?

For wolf its the TB i was asking you about. you pointed me to a different one but im stuck on the over looks for the speaker it self, lol.

[LouC]

If it's truly a midrange, and you cross it a bit higher than the box resonance, the box size/qts becomes effectively irrelevant. The "air spring" effect for sealed boxes will only help control the bottom end. If the driver is calling for that small a box, it probably has limited excursion and power handling. You might be safer to cross it higher and let the electrics control the slope.

If you do want an easy way to make small chambers, short lengths of pvc or abs pipe sealed at the back are pretty easy. Hot melt, silicone or construction adhesive will compensate for any irregularities in cutting the pipe.

[Æ]

Back in Speaker Builder Magazine year 2000, Jim Moriyasu did a series of articles entitled "A Study of Midrange Enclosures."
Supported by plenty of response curves, waterfall plots etc.

His conclusion: Now it starts to appear that size of the enclosure, rather than its shape, has a greater effect on the response. Not only was a larger rectangular enclosure better than a smaller one. . . .

Bigger is better.

[Chris Roemer]

Back in Speaker Builder Magazine year 2000, Jim Moriyasu did a series of articles entitled "A Study of Midrange Enclosures."
Supported by plenty of response curves, waterfall plots etc.

His conclusion: Now it starts to appear that size of the enclosure, rather than its shape, has a greater effect on the response. Not only was a larger rectangular enclosure better than a smaller one. . . .

Bigger is better.

I use BOTH WinISDs, all the time. Alpha (Pro) tells you a lot more, but I like beta for a quick look (all you have to enter is Vas, Qts, and Fs, and for box modelling, you can pick ANY driver - even a 12" - and just type right over its parameters) AND its nifty box dimensions calculator (which the Pro version just never got).

It shows an F3 of 440 Hz in a 2.2 cu. INCH box, with a Q of 0.70.

Chris

[Mike E]

If it's truly a midrange, and you cross it a bit higher than the box resonance, the box size/qts becomes effectively irrelevant. The "air spring" effect for sealed boxes will only help control the bottom end. If the driver is calling for that small a box, it probably has limited excursion and power handling. You might be safer to cross it higher and let the electrics control the slope.

If you do want an easy way to make small chambers, short lengths of pvc or abs pipe sealed at the back are pretty easy. Hot melt, silicone or construction adhesive will compensate for any irregularities in cutting the pipe.

right the TB W2-748SG only has 10watt RMS and a .75mm Xmax.

Back in Speaker Builder Magazine year 2000, Jim Moriyasu did a series of articles entitled "A Study of Midrange Enclosures."
Supported by plenty of response curves, waterfall plots etc.

His conclusion: Now it starts to appear that size of the enclosure, rather than its shape, has a greater effect on the response. Not only was a larger rectangular enclosure better than a smaller one. . . .

Bigger is better.

hmm interesting, well i am looking to adjust box size. since it is so small and effects the natural roll off and F3 of the driver. kinda why i would like to use the natural roll off with a first order to achieve a 2nd order. though i need to look into the ND105-4 driver im looking to use for the rest of the bottom end. right now im just thinking off the top my head... i have weird driver combo's or so i think but never able to build anything. was suprised to finally see someone build my TB 704d/XT25 two way even if a MTM. Yea i thought about that driver combo when the 704D came out.

I use BOTH WinISDs, all the time. Alpha (Pro) tells you a lot more, but I like beta for a quick look (all you have to enter is Vas, Qts, and Fs, and for box modelling, you can pick ANY driver - even a 12" - and just type right over its parameters) AND its nifty box dimensions calculator (which the Pro version just never got).

It shows an F3 of 440 Hz in a 2.2 cu. INCH box, with a Q of 0.70.

Chris

i could go with a .0024 cu ft for a F3 of 462hz or .0022 cu ft for F3 of 457hz or even .002 for a F3 of 451hz. i guess i need to grab/find that XO spread sheet and start playing around..

[DanP]

The natural roll off should already be 2nd order, but you're definitely going to want at least a cap on it to reduce excursion. As far as your enclosure size goes, feel free to experiment, but the changes in F3 that you're talking about are on the order of 1% - I don't think you are going to hear much of a difference. Err a little on the large side and call it good.

Dan

[Mike E]

The natural roll off should already be 2nd order, but you're definitely going to want at least a cap on it to reduce excursion. As far as your enclosure size goes, feel free to experiment, but the changes in F3 that you're talking about are on the order of 1% - I don't think you are going to hear much of a difference. Err a little on the large side and call it good.

Dan

even at 1% wouldn't the slight difference allow for different phase alignments as well. in regards to trying to phase align with the ND105-4 in the xo? im not realy worried about hearing much difference more then being able to a good phase alignment with the two drivers.

if there is a 2nd order xo around the 400-460hz range. i thought the excursion would already be limited in that way.