2 X 11 cu ft Q18 slot ported subs build - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #21 of 237 Old 01-27-10, 06:48 PM
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Re: 2 X 11 cu ft Q18 slot ported subs build

I usually router the port before I assemble.
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post #22 of 237 Old 01-27-10, 11:40 PM Thread Starter
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Re: 2 X 11 cu ft Q18 slot ported subs build

Ryan,

The reason I have left it like that is because I may add an extra baffle on the front or extend the front of the port ( a bit like the ED A7-900 ) and then put the grill underneath. I am going to see what port noise I might get from it as it is first and then decide.

cheers

Graham
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post #23 of 237 Old 01-28-10, 12:13 AM
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Ryan
 
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Re: 2 X 11 cu ft Q18 slot ported subs build

gotcha! I'm excited... these are the 2 Q 18's we were talkin about for a while, right? Youre trying/hoping to get more low end?
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post #24 of 237 Old 01-28-10, 12:23 AM Thread Starter
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Re: 2 X 11 cu ft Q18 slot ported subs build

Ryan,

Sure are matey. Yep I am hoping for more low end. It will be my first ported sub/s so as with the sealed sub its a big learning curve for me and I am taking a few risks with the spec of these subs with regards to port velocity, port resonance but hey that is what makes it interesting.

Hopefully fingers crossed it should work out ok. I will find out tomorrow.

cheers
Graham
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post #25 of 237 Old 01-28-10, 12:39 AM
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Re: 2 X 11 cu ft Q18 slot ported subs build

well I've been dealing with port velocity myself, and I've always wondered about port resonance... I just don't see it as a problem, yet.... I got mine crossed for ya too!
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post #26 of 237 Old 01-28-10, 12:50 AM Thread Starter
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Re: 2 X 11 cu ft Q18 slot ported subs build

Ryan

Ive read so many threads debating on this subject and whether having a low port resonance is audible or not and so on. I think from reading sub junkies sub, his 1st port resonance is about 100hz I think and he's never mentioned any issues. Not sure what he is crossing his sub at.

My main problem was to get a higher 1st port resonance of say 200 or above it made the tuning quite high when modelling the Q drivers which I didn't want.

My 1st port resonance is about 138hz. According to MikeP if I cross the sub at 80hz I should be fine.

My port velocity without a hpf is 30 m/s at 11.5hz which is the max excursion on my 13.5hz tune and only 17 m/s at 15hz. With a hpf it is only 20 m/s max.


I should finish the sub today. Just got to sort out the speaker wire/plate, egg crate foam and just the bottom and its done. I will probably leave it overnight tonight to dry completely and test it tomorrow.

cheers

Graham
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post #27 of 237 Old 01-28-10, 08:17 AM Thread Starter
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Re: 2 X 11 cu ft Q18 slot ported subs build

A little update......

I have now put the bottom on and filled/sanded all the holes. I need to sand and fill again once that has dried. I will then sand down everything again to smooth off for when I add the wood veneer.

I have put the speaker plate on and cable tied the speaker wire ready for when the driver goes in.

Tomorrow morning I will add the egg crate foam (need to buy some adhesive spray) and just put the side on, then fill and sand. Job done ish!

I emailed the european seller for the reckhorn B2 and got a quote of 59 euros plus 15 euros for delivery just in case I need one. If I do get any port noise then adding the reckhorn will reduce the velocity alot.

The bracing is really solid. More solid than I thought it would be especially as it only has a 1.5" frame.

Probably used more screws than I was going to but Im just not confident enough to use just glue.
Maybe in the future I may do one with normal wood glue to see the difference.

cheers

Graham
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post #28 of 237 Old 01-28-10, 06:22 PM
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Re: 2 X 11 cu ft Q18 slot ported subs build

Wow. I like how you have the wires running. It looks really clean.

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post #29 of 237 Old 01-28-10, 06:28 PM Thread Starter
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Re: 2 X 11 cu ft Q18 slot ported subs build

Dylan,

Just the egg crate to add and put on the side and Im done. Fill and sand the side and I can start testing. I have just looked at the application notes on the tempest x2 drivers and the difference between what is measure at 1m (in winisd too) is alot lower than in room response so am I to think there will be a fair bit of gain on top of what my graph in winisd is showing in the real world.

cheers

Graham
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post #30 of 237 Old 01-28-10, 07:44 PM
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Re: 2 X 11 cu ft Q18 slot ported subs build

Great work Graham, this will be one great subwoofer. And to think there will be 2 of these beast's.

The slotted ports are the way to go I think they help to finish the box off nicely.
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