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2 custom built DIY ported Fi 18" subs on the way.

22K views 131 replies 6 participants last post by  sunnyhd 
#1 ·
This week I am going to be helping a friend remodel his front setup. He sold his commercial sub, and is replacing it with 2 new DIY ones with some help from me :D

Basically, he has a timber frame built at the front which houses his screen, speakers, and now we are going to build these 2 subs in there as well. I have added some images below so you can get a better idea of how this is going to work. Any thoughts on the design are welcomed, the final design isnt set in stone yet, but I dont think it will be far from this at all.

My main thoughts are concerning the location of the drivers, and the ports. As the images reveal, the drivers will be in a front left and right position, while the ports will likely end up in a centrally located position, right net to each other. Any thoughts on how this will affect performance is greatly welcomed.

The drivers will be Fi Q18's. The cab is 230 litres, and will be tuned to 19hz (note: The final design used 250 litres and was tuned to 18hz). I think a HPF at 10hz is worth using, and they will be powered with a Crown K2. EQ will be provided by the SVS AS-EQ1. The image shows one sub (the left one) and the other will be the same but obviously the other way around. The port is 400mm x 100mm and is around 1250mm long IIRC.
 

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#30 ·
After using titebond wood glue, I wouldn't use anything else now. Its easy to clean off and sands really easily. The bond and seal stuff Dan mentioned is great stuff but very messy and a pain to sand down.

Looking forward to the results on this Dan. Keep up the good work mate. :T

As Dan mentioned the EQ.2 cost me about £100 ($150) delivered. Great Device but I think I like the idea off the Behringer mic2200 so I may look at one off those in the future.


cheers

Graham
 
#34 ·
Im in the ventilation trade, so gasket is something I can get all I want of for free. I'll be using a sticky backed foam gasket used in the installation of ductwork ventilation systems. The cabinet will simply be raw MDF, as once its installed there is a kind of velvet black material going across the front of the room to hide it all. I also have access to pyrosorb (a kind of acoustic foam used in the construction of attenuators), which I can use to kill any resonances if required.
 
#37 ·
Just spoke to DV247.com and The gentleman over the phone thinks Behringer MIC2200 Ultragain Pro 2 Channel Tube Mic Preamp is NO GOOD for Sub HPF What I need is this.... DBX 234XL Stereo Crossover or DBX 223XL Stereo 2 Way / Mono 3-Way Crossover
Any Thoughts ?????
 
#39 ·
Will do :R also They don't have it in stock
Since You guys are so sure I will find someone who has it..
Just one more thing.... Does this go between SVS EQ and K2 or between Onkyo 5507 and SVS EQ?

if any of you have this Could you let me know what Cables are best?
I will be using as it is at the moment 5507 with XLR to Phono in SVS EQ and from Phono from SVS EQ to XLR in Crown K2 and from K2 Sub we are using a Speaker cable..
I want to order the right cable with The behringer so its here on tuesday with everything.
Many thanks
 
#40 ·
Put it after the SVS, otherwise it will be trying to boost out the frequencies the HPF cuts out which is kinda pointless, and potentially a waist of filters, effectively reducing filter resolution. I dont know enough about the device myself to comment on it directly, other than what you can read about it on the net yourself.
 
#41 ·
#42 ·
Just managed to make another box today, It was much easier this time as I copied the box previously made by Dan. Now the best part is cutting the hole and slot. Which I am leaving it to Dan.












My Subs arrived with 12 metre cable..
Also HPS filter, Behringer MIC2200 Ultragain Pro 2 with two XLR cables

So I am all ready now to get this finished by tomorrow evening. Hope you are up for it Dan :D

James
 
#44 ·
No pics of the drivers :eek: :D

Did you put plenty of glue on, I see there doesnt seem to be as much oozing out with your box, but then maybe your just neater then I :p. It all looks good though, so tomorrow we will fit the braces, and do the cutouts on the front baffle. Hopefully we can et these running y the end of play tomorrow :T
 
#47 ·
The ports only needed to be 850mm long for a 19hz tune. The design did change slightly from the very first model after I visited Sunny and took some measurements of his room. We were able to slightly increase the cab volume and we reduced the size of the port from 400 x 100 to 400 x 75, meaning we could shorten the port, increase the resonance and increase the cabinet volume slightly further still.

We still have the required 11 inches depth once the front panel is fitted and the driver mounted into it.
 
#49 · (Edited)
Hi Graham, its Moon on Sunny's computer, we've just sat down after a very busy day - phew :sweat:

You'll be pleased to hear the boxes the boxes are built now, installed, and the drivers are in. There is still plenty to do, but we couldnt resist quick listen. These drivers have no vent on the rear, which I was surprised at to be honest, but it obviously means the proximity of the rear of the drivers to the back of the cab is a non issue.

Pictures will follow when James uploads them. First impressions are pretty good. There is some cleaning up to do as they dont sound as tight to me as I'm sure they will, but boy these things ooze power and just deliver the bass without any effort. I think they could sound deeper, but I'm sure some eq and running in will deliver that, and you can really feel the suckers in this room. Music so far is pretty promising, and any concerns I may have had with the ports being noisy has vanished, there isnt even a gentle breeze coming from them.

James is going to finish things off tomorrow, including all the aesthetics stuff. On Friday I'm going to come back, and we will hook up the SVS SA EQ-1 and the HPF, do all the eq'ing and even fit in a film if we get time.
 
#50 ·
Dan,

That's great news mate. I found that my drivers took a while to loosen up. Did you run some sinewaves through them first. I ran a mix off 10 and 20hz tones through mine for a few hours with short bursts. Scott at FI told me to get them running at about 1-2" excursion but I was too scared to do that. After I did this it made a massive difference. I am interested to see how your graphs are with a 19hz tune and how much below that you get.

With regards to air velocity, I am not surprised as my current subs with no hpf run at 38 m/s off velocity at 10hz on full power and even at -10db on bassotronics I don't get any chuffing at all, just a slight amount off air. I guess that the higher tune you go the more turbelence you get.

These drivers to take alot off abuse and are very understated as you guys will find out. They will eat an EP4000 each quite easily.

Looking forward to the pics.

cheers

Graham
 
#51 ·
The drivers only landed the day before yesterday, and plugging them in yesterday was the first time they had been run. I'm sure Sunny will stretch their legs a bit though. We plan to get them setup properly on Friday so we will give them a little work out to get them going. I'm gonna take over my laptop on Friday too so we can run REW and see ow things looks, so yeah thats going to be interesting. To me they dont sound quite as deep as my sealed sub, or as quick, but they certainly give a feeling of being much more powerful, as well they should.

The air speed aspect is positive. So far there is very little air movement, so chuffing really isnt going to be a concern. I was more worried we might be able to just hear a little bit of air movement in general, but there really isnt that much so I'm pleasantly surprised there, but we'll see how things go as we crank up the volume and stretch their legs. All in all though, I'm pretty pleased with my first ported build, and Sunny certainly seemed impressed with the initial play :T

One thing I dont get is why you thing theses will eat an EP4000. In a well designed sub you dont want the drivers to 'eat' the amp or vice versa, and in certain configurations you could quite easily get an EP 4000 to kill one of these drivers. You could configure it at the opposite ed of the spectrum, possibly killing the amp, and probably still damaging the drivers. What your after is a balance, and the EP 4000 is more than happy to deliver 1000 watts per channel all day long, which should be plenty for a ported sub. That said though, Sunny is currently running an Crown K2. He was talking about getting an EP4000, but we will see how this amp performs first. One big plus for the K2, and the reason Sunny went for it, is that it doesnt use a fan to cool it. Obviously it runs warmer, but its designed to run like that so all is good as long as its low end performance is upto scratch. We shall see.
 
#53 · (Edited)
Dan,

You know I am a bass head matey. In an ideal world I would love to run 4 off these in my room with two EP4000 amps but that's me.

I have to say these drivers never fail to impress me and I wish I could compare the old ones with the new ones to see how different they sound. In winisd in a 15 cu ft box (my new subs) there is alot less excursion running the same tunes on the new drivers. The new Q's model better in the low end in the same box but this is with twice the power off the old Q's.

Looking forward to the graphs though.

Dan, just saw the pics and the jumper. LOL. Looks really good mate. Are you going to route the exit ports on the outer piece.
Is that the optimum place for the subs in the room.

cheers

Graham
 
#55 ·
Dan, just saw the pics and the jumper. LOL. Looks really good mate. Are you going to route the exit ports on the outer piece.
Is that the optimum place for the subs in the room.

cheers

Graham
We were considering getting rid of the frame round the ports if it was required as the extra in isnt required as part of the ports length. We made those oversized to minimise the effect they would have on the port, again with the view the we could mod them or remove them if required. Sunny wants to keep them on so he can glue the fabric to them an not have any loose material close to the ports. When we first ran the subs, they are working so far within their capabilities that there is only a gentle breeze coming from them even a ref level, so I dont think we need to modify them at all. If we find we need to mod them at any point, the front baffles are removable (did you spot the green foam gasket?) so its not difficult to do so.

As for placement, well we have yet to do any measuring and testing, and the positions were pretty much dictated by Sunny's goals on aesthetics. That said, time and again I have found the placing dual subs up front with the front left and right yields top results. Even so, when you have dual subs, and in Sunny's case an high end dedicated dual sub eq device, placement becomes less of an issue and less of a gamble. Already we have noticed just how much better the room is filled with bass. Based on my ears, I think the in room response is pretty decent for a start, and will only improve.
 
#56 ·
That's great news for Sunny. I found in my room that having front facing subs in the middle sounded light in the bass area when compared to how I have them now which is facing outwards away from the corners but every room is different. I was going to build something like that instead of two singles but changed my mind because of the sound issue.

Looks good though and very imposing on the watching audience.

Cheers

Graham
 
#57 ·
They arent in the middle. The ports are, but the drivers about a quarter of the way in from the edges. We did that on purpose as we didnt want them too close to the edges. We have no issue with the bass sounding weak :T

Sunny should have got the tarting up complete today, as well as the final bits and bobs we couldnt get done yesterday. Once complete I think these will be surprisingly discreet, and his room will be even less filled with subs that it was when he owned the PB13U. Hopefully he will have time to upload the images tonight, I'm looking forward to seeing those myself.
 
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