Qtc and amp questions - AVS Forum
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post #1 of 11 Old 08-29-2013, 03:07 PM - Thread Starter
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I've built my sealed subs with a Qtc of .7, which seems to always be recommended, but I've always been curious what it would sound like with a lower or higher Q. Can I change the Q electronically or is this mostly a function of the size of the box?

I was thinking about buying the Rythmic amp, not sure if this is good without a Rythmic sub but it has PEQ, Delay/phase, low pass slope setting, rumble filter, damping filter, etc.
Could I get the same settings using the Behringer or minidsp?


Thanks.
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post #2 of 11 Old 08-29-2013, 03:13 PM
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I've built my sealed subs with a Qtc of .7, which seems to always be recommended, but I've always been curious what it would sound like with a lower or higher Q.
Lower Q will extend frequency response lower, at the cost of overall sensitivity.
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Can I change the Q electronically or is this mostly a function of the size of the box?
The size of the box and/or the amount of damping material in it.

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post #3 of 11 Old 08-29-2013, 06:28 PM - Thread Starter
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Thank you. So it's a waste to purchase any other electronics and I should just try different cabinet sizes and stuffing?
I have read different descriptions of higher and lower Q, but like most things it's better to experience it and decide for yourself what you like.
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post #4 of 11 Old 08-29-2013, 07:16 PM
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So it's a waste to purchase any other electronics and I should just try different cabinet sizes and stuffing?
No, because different cab sizes and stuffing can't correct in-room response.

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post #5 of 11 Old 08-29-2013, 08:13 PM - Thread Starter
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What would you recommend if I would like to test differences in Q values? Build a new box, add/ remove stuffing, add an external Dsp? I'm trying to learn about Q values right now. I just don't correlate other people's descriptions with my own experiences. That's why I want to experiment.
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post #6 of 11 Old 08-29-2013, 08:35 PM - Thread Starter
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I do a lot of furniture building so I built this down firing sub. I learned about wood working by trial and error, not by what one person said was the best. And that is what I'm trying to do here with subs. So forgive me if I'm not asking the right questions. But this hobby is a lot more expensive than buying different types of wood and trying different ways to join wood. By adjusting different values, I can then learn what's important to me.
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post #7 of 11 Old 08-29-2013, 09:33 PM
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it is easy to change the q of an enclosure by simply putting something like wood blocks inside of it.

the smaller the enclosure, the higher the q.

others have performed a similar test. a search may pull up some results.

the frequency response changes, so applying eq to bring it back to baseline is also something to experiment with.

some argue that once you adjust the frequency response back, the q of the unadjusted system is irrelevant. others say, it still matters but only a bit. others say it is a night and day difference.

:-)

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post #8 of 11 Old 08-29-2013, 09:34 PM
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also, there is a method to change the q of the system electronically, but I don't know how that is done or where to point you.

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post #9 of 11 Old 08-30-2013, 05:31 AM
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Quote:
Originally Posted by DustinF View Post

What would you recommend if I would like to test differences in Q values? Build a new box, add/ remove stuffing, add an external Dsp? I'm trying to learn about Q values right now. I just don't correlate other people's descriptions with my own experiences. That's why I want to experiment.
You can use EQ to emulate the result of different Q values, then incorporate those results into the modeling process.

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post #10 of 11 Old 08-30-2013, 07:26 AM
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Quote:
Originally Posted by DustinF View Post



I do a lot of furniture building so I built this down firing sub. I learned about wood working by trial and error, not by what one person said was the best. And that is what I'm trying to do here with subs. So forgive me if I'm not asking the right questions. But this hobby is a lot more expensive than buying different types of wood and trying different ways to join wood. By adjusting different values, I can then learn what's important to me.
That's an awesome cabinet, stealth! biggrin.gif
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post #11 of 11 Old 08-30-2013, 11:24 AM - Thread Starter
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Thank you. It's actually really easy because I'm not creating any structural joints, and the door and drawer are false.
Each piece of the hardwood is just glued to the mdf. Just in a couple of spots so to allow expansion and contraction of the wood.

And thank you LTD02 and Bill. I think I will try a minidsp, as it seems to offer the same or more than the behringer or the rythmic amp.
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