DIY Subwoofer help needed after reading. - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 39 Old 10-26-2015, 04:59 PM
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Quote:
Originally Posted by nanoodhaliwal View Post
Actually I was asking if I should get Amp with dsp now or miniDsp later is better option, till then I will be using my AVR.
You will need the DSP now, to provide a High Pass filter, which protects your subwoofer driver from exploding. The AVR won't do that.

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post #32 of 39 Old 10-26-2015, 05:49 PM
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Originally Posted by nanoodhaliwal View Post
Thanks John. Any specific reason for recommending 460HO over UM18 ? or just because of the box size requirements ?

I have Denon with 2 subwoofer outputs and Audyssey to tune them. I might get miniDsp later. So, question is do I need to get amp with DSP or I should be fine for now ?

Again Thanks for you reply.

the upper bass performance may be a little better on the ho, but the um does have more low end potential.

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post #33 of 39 Old 10-26-2015, 06:45 PM
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Quote:
Originally Posted by Augerhandle View Post
You will need the DSP now, to provide a High Pass filter, which protects your subwoofer driver from exploding. The AVR won't do that.
Would the AVR not provide a high pass filter/crossover if using the subwoofer out port? I would agree if you were trying to send full frequency to the sub could cause a lot of problems. The DSP would provide it with a lot more options and tune ability, but if you were using a decent AVR should it not have a crossover on the sub out outputs?
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post #34 of 39 Old 10-26-2015, 07:29 PM
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Originally Posted by BSHuff View Post
Would the AVR not provide a high pass filter/crossover if using the subwoofer out port? I would agree if you were trying to send full frequency to the sub could cause a lot of problems. The DSP would provide it with a lot more options and tune ability, but if you were using a decent AVR should it not have a crossover on the sub out outputs?

I think you're confusing High Pass with Low Pass.


Low Pass passes everything lower than its setting and attenuates higher frequencies, usually set to roll off somewhere like 60-120 Hz. Your AVR should be able to do that. A High Pass works the other way. It passes everything higher than its setting and attenuates the lower frequencies, usually frequencies below 30 Hz, and in Home Theater setups can work much lower.


A ported subwoofer will unload below its tuning frequency and can be damaged with very little power. If you have a ported box tuned to 25 Hz, you should set a High Pass to attenuate or cut everything below that.

In the first graph, excursion is plotted with a 25 HZ tune. Note that with no High Pass filter in place, excursion shoots upward past Xmax below about 20 Hz. Some movies have content below 20 Hz which can damage the driver.


In the second graph, a High Pass filter set at 22 Hz attenuates the signal below that setting (thereby reducing excursion), and keeps the driver safe below tune (as safe at it would be at any other frequencies, as it can still be damaged by too much power).







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post #35 of 39 Old 10-27-2015, 07:29 AM - Thread Starter
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Originally Posted by LTD02 View Post
the upper bass performance may be a little better on the ho, but the um does have more low end potential.
Thanks John. So UM is better for movies I guess. I went ahead and bought UM18, hope I made the right choice. I will do mini marty for now and upgrade to full marty later.

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Originally Posted by Augerhandle View Post
You will need the DSP now, to provide a High Pass filter, which protects your subwoofer driver from exploding. The AVR won't do that.
Thanks bought iNuke6000DSP
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post #36 of 39 Old 10-27-2015, 09:26 AM
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@Augerhandle yep, was confused. My Navy Electronics instructor is probably shaking his head right now... Been a few decades since I looked at signal filtering.
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post #37 of 39 Old 11-19-2015, 08:01 AM - Thread Starter
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Here is where I am right now, don't get much time so going slow. This is also my first sub build. The front padding is not glued, I have to seal the front baffle before I glue them.
Let me know what you guys think. I might need tuning help after this :P
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post #38 of 39 Old 08-28-2017, 02:52 PM
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Originally Posted by LTD02 View Post
can' really go wrong with any of the suggestions, it just depends on what you are trying to maximize.

i seem to be suggesting the 460ho driver a lot lately, so i'll stick with that.

6000dsp for amp. measured output into 4 ohms is around 1.8kw which is more than is needed.


1250 watts get you this:





two subs pulling together would provide up to about +6db.


revised and updated mini-marty 2015 cabinet.








the same performance can be achieved by changing the dimensions around so long as the port size and length are kept the same and the internal volume is kept the same.


maximum output vs sealed 3.5 cubic feet with same driver and power.

Hi, I already have the wood and i am ready to cut it ans start the building process but now I have 2 different blueprints of the minimarty, 1 with 3 inches port height and this one with 2.5 inches height.

Witch one is right?
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post #39 of 39 Old 08-28-2017, 08:57 PM
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Originally Posted by Jonathan Pacheco Vasquez View Post
Hi, I already have the wood and i am ready to cut it ans start the building process but now I have 2 different blueprints of the minimarty, 1 with 3 inches port height and this one with 2.5 inches height.

Witch one is right?

there have been many marty designs and plans over the years and countless variants. they all work. :-)


if you are shooting for 17hz tuning, the "revised 2015" plan is a good one.


the 3" port, iirc, was slightly longer, had a slightly higher tuning frequency (18-19hz iirc), a slightly lower first port resonance, and slightly lower air velocity.


honestly, you can't go wrong either way.

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