In Cabinet Subs Build

markymiles

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At the very early stages of this, but considering literally pushing two FF Sub boxes into my unit.

Unit I have is this:

bm7b.jpg


If I move things around I can have the outside compartments empty which will leave room inside for two boxes. The boxes can be 21" W x 17" H x 19" Deep. I was thinking I could squeeze a 15" driver in each. Volume around 70L net with a bit of polifill should be able to get 80l or so. Not decided completely on drivers yet but do favour the Si HT15's because they should run off my existing amp and also I like what I've read about their characteristics.

Before I really get going with this is there anything inherently wrong with putting subs inside cabinets. I could maybe have them sitting on a little acoustic foam if that would make any difference. I would obviously remove the sliding doors :)

Only bit that I'm not looking forward to is making grilles to cover the drivers as unlike some of you drivers showing is a big no no in my house with the good lady.
 
personally I cant see any real issues as long as the box is very solid, will it be a very tight fit, are the glass doors coming off.

so what where your thought on the q18 then.

also with 2x sub how do you plan to run them off the nu3000.
 
I still very much love my q18 but this solution would be neater and hopefully allow a more even spread around the room. Two over one seems to be the favoured option. I was thinking about one sub off each channel. The HT15's are only rated at 600w but the inuke6000 would probably be the better option so may sell everything I have now as a job lot.

Yes of course the glass doors would come off. The unit is a two and a three, I would need to swap them around so that the outsides where the subs would be would be one set of drawers and one shelves.
 
, im confident that an nu3000 wouldn't run a si 15 of each channel, mine couldn't run my aes and just clipped and popped, so you could get 2x dual 4 ohms drivers and run them of the nu3000 in bridged or get and nu6000 as you said.
 
Yeah scott that was what I meant. I could run a dual 4 ohm driver from each channel on the inuke or all together bridged. Should give me 400w spare for each.

The 6000 would give 1700w or so to each driver, so loads more to spare. Would prefer the 6000 but means taking a bigger hit on my current set up
 
the nu3000 is like 2x 600w rms at 4ohm, so if you got dual 2ohm drivers you couldn't wire both to be used on a bridged nu3000, you need dual 4ohm drivers for that.

if you get and nu6000 you need dual 2 ohm driver.

nope sorry yes get dual 4 ohm drivers and run each sub of a channel of an nu3000 wired for 2 ohms per driver, that will give you 1100wrms so should be ok.(forgot about 2ohm mode)
 
If you go with the SI HT subs then D4 and 1100w each from a channel each should be about the max you could safely use. You would need to work out the internal space each would have and model in WinISD to check excursion and power draw. You could also download REW and put in your room measurements so you can move subs round in the room-response modeller to see where would be best :)

I still personally think a dual opposed in the same position as current (one facing up, one facing down) with something like the top version of the Fi subs (so you can max the power input safely to overcome the small box size) would see you right! :)
 
I'm going to see if I can sell what I've got first for before I go any further. If I am only offered peanuts then the whole thing will be shelved.

The idea behind two is to get better response and with this plan they can come into the room as well and not be stuck in the corner. Memx thanks but no I won't be getting what you mention. I want to limit my losses so Fi are out of the question. I have modelled two siht15's and they look pretty good to me. Jamesvicky is very happy with his pair of siht15's which got me thinking they should be ample.

Yeah ideally I could build another enclosure and have ht18's in each corner but she won't play ball with that idea.

No chance of rew modelling as I don't have a square room unfortunately.
 
No chance of rew modelling as I don't have a square room unfortunately.
This would be v accurate with temporally accurate measurements (not possible with USB mic) but should be doable with a USB mic as the distances look pretty similar. There can be other differences (in the entire signal chain) that make the delays between individual measurements inconsistent (a home OS is not a realtime operating system after all) though so don't take this as gospel unless you use a different mic. If you have an SPL meter then that would also work as you could just do a loopback over your soundcard as exact accuracy in the FR is not that important here, just the nature of the summed response. Anyway...

Move your sub into position A, take a measurement and measure the distance from sub to mic. Repeat for position B. Look at each measurement in the impulse window, you should see each peak aligned to t=0 something like this

snapshot1.png

If the distances are basically identical then the next bit isn't required.... you now need to manually shift one of the measurements to time align them, press the control button and apply the required distance shift to one of the measurements.

snapshot3.png

Now you can combine them by going to the "All SPL" window, click controls, pick the 2 traces, select A + B and then click generate.

snapshot2.png
When you do this REW is correctly summing the 2 signals so the resulting trace will give you an idea of what you can expect from putting 2 subs into those positions.
 
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Hi matt, bit confused, isn't what you have just posted after I have the subs. Perhaps I wasn't being clear when I said no chance for rew modelling, I meant using the room sim, which I think needs square/rectangular rooms to work.
 
Hi matt, bit confused, isn't what you have just posted after I have the subs. Perhaps I wasn't being clear when I said no chance for rew modelling, I meant using the room sim, which I think needs square/rectangular rooms to work.
You can use your current subs to get an idea. You just have to move them around into place
 
Ahh got you, that's a big job. Hadn't thought to try using my sub, just assumed they would be quite different. Will involve a lot of cable, cabinet moving. But would be useful to have a rough idea prior to changing anything. Might be a fruitless mission and you woulnd't know until too late.

That's for taking the time on your post. The subs would be fairly equidistant from the mlp. I did plan on cheating and just use the onkyo to measure the distance to each sub separately and then work out the delay needed to add to the nearest sub using the inuke. Your method is obviously more accurate.
 
Guessing your too far away for a listen then mate?
 
Sorry mate lots going on, meant to reply. Yeah I'm in surrey
 
So looks like my sub is sold. So it's full steam ahead .

I read on here from Dan I think that the si ht15 needs a much bigger box than the fi q. I'm a bit confused as I modelled both on win isd and I get Qtc of 0.707 with 75 l on the si and fairly similar on the fi q. Is this right could someone please double check. I'm obviously limited on space and 70l without polifill is my absolute max which seems ideal to me with polifill giving 25% or so extra volume.

I am tempted to wait for the new ae drivers but no idea on pricing so could easily be as expensive as the Fi drivers which I can't really afford. Then there's also the si hst to consider. Although I am gonna be subless for a bit don't want to rush into any decisions right now. Cost wise the si ht are top of my list obviously.

Looking like Inuke 6000dsp will be my amp at least that is a pretty easy decision. Although for another 100 could get a cv2800 and mini Dsp.
 
70l will be fine, and that's from experience :)
 
Thanks James, is that roughly what your's were. You didn't do a build thread did you, had a quick look couldn't find anything. Honestly the cheek of it building your own subs and not putting it all on here lol.
 
So little bit of modelling on win isd. Am I right I just double everything ie box size, no. of drivers and power to get simulated two boxes solution. Or is it assuming they are in one enclosure, not sure if that makes any difference. I have put in the max rms they can handle. There is a suggestion that the SI are conservative and can handle a bit more than 600W. If they reached the 2 x FI Q line then I would be very happy. Otherwise it looks like I won't be gaining any extension over my single Q18, which would be a little disappointing although obviously that isn't the main reason for the project.

Just trying to get a feel for what I might achieve. Q18 (current) is orange, 2 x SI HT15 is yellow. 2 x Fi Q15 is red.

SPL Charts.jpg
 
I think that may give you an overly optimistic view by a few dB, i.e. colocating (subs positioned within 1/4 wavelength of the crossover of each other, aka ~3.5-4' for an 80Hz XO) gives you +6dB whereas non colocated means more like +3dB
 
I think that may give you an overly optimistic view by a few dB, i.e. colocating (subs positioned within 1/4 wavelength of the crossover of each other, aka ~3.5-4' for an 80Hz XO) gives you +6dB whereas non colocated means more like +3dB
matt my subs are positioned 17ft apart and give a 6db increase.
 
So going for the worst case scenario I would only just about get the same output with two q15's as my q18. The Si's unless very lucky would be down on my q18. Hmmm.

At least I have 5 holes in the cabinet where the subs could fit. Gives me the chance to pick the best two combined.

Wonder where the new ae's will fit, above or below the q's output
 
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So going for the worst case scenario I would only just about get the same output with two q15's as my q18. The Si's unless very lucky would be down on my q18. Hmmm.

At least I have 5 holes in the cabinet where the subs could fit. Gives me the chance to pick the best two combined.

Wonder where the new ae's will fit, above or below the q's output
the q is why are you changing? if it's for a smoother response, and you get it, then surely a few dB headroom here or there is basically irrelevant unless you're already really caning it
 
I know what you mean, but it's a bit psychological, never downgrade!! Well try not to anyway.

It is mostly about aesthetics in the room and hopefully a more even response. But ideally I wouldn't lose headroom doing it either.
 
well you're about 2dB down in the area where room modes are probably giving you the most free boost (don't know your room size but average UK size rooms produce 1st modes in the 30-40Hz region) so I doubt the 2dB would be at all noticeable
 

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