Another "build a pair of subs" thread

MaxeII

Active Member
So the drivers have a thin gasket strip already stuck on. Is it adequate? Or should I also apply a thin strip to the MDF before mounting? If so, what are others using?
Not that I am anywhere near that stage. But I want to get everything ordered.
 

MemX

Well-known Member
So the drivers have a thin gasket strip already stuck on. Is it adequate? Or should I also apply a thin strip to the MDF before mounting? If so, what are others using?
Not that I am anywhere near that stage. But I want to get everything ordered.
Ummm... pass?!

I would think (hope) the supplied one would work if the manufacturer is providing it!

Could be worth dropping them a line.
 

markymiles

Distinguished Member
I used some of this, works great. Not convinced you need it if your driver is making a good seal, but you know we over do things just to be sure!!

 

MaxeII

Active Member
So I'm looking at wood glue now.

I'm not entirely confident in my cuts, but I don't like the sound of the expanding stuff. Plus I'm thinking about gluing and screwing rather than clamping, as I don't own large clamps and this is likely to be a one off use.

After going through various sites, I'm seeing Gorilla (PVA) and Titebond Original or Ultimate seem to be the most common. I'm fairly set (pun) on Gorilla PVA as it has a bit more working time and being a bit cheaper. Any thoughts or experiences to suggest otherwise?

The question then is how much am I likely to need for 2 enclosures?

It'll be something like 680mm x 540mm x 380mm but I'm still tinkering with that. I may build a single wall box initially and give it a test before deciding on going double wall or just adding the 2nd baffle wall. Is 2 litres likely to be enough if I do go double wall and triple baffle?
 
Last edited:

MaxeII

Active Member
Can someone please help me understand the possibilities with DSP and EQ'ing. I'll have a Behringer with DSP and DIRAC for the final calibration.
Looking at the attached graph. Am I right in thinking that I will be able to flatten the response from 10Hz to 120Hz at 105dB?
I know there will be some dips and spikes in the real response, but am I right otherwise? I feel daft asking, but I just want to be sure I've got it right.
 

Attachments

  • Image4.jpg
    Image4.jpg
    70.5 KB · Views: 30
Last edited:

john01707

Active Member
The titebond is superb, I am a carpenter and this is what i would use. Also i would go with a double baffle, and i did a double layer of 3/4" and 1/2" mdf all round on my build. I used valchromat mdf which is very dense but a bit pricey. Maybe a bit excessive but they are super solid. 1 litre of the titebond will do you. you can check out my build thread if you like.
 

john01707

Active Member
p.s If your not very confident cutting the material you could get the whole lot cut on a cnc machine, (not expensive)
 

MaxeII

Active Member
Thanks. I've looked at your build thread a few times now. Very impressive.

I did take note of your previous comment here, so I had it at the top of my list when I started looking. But I meant to ask you if you were referring to the Titebond Original?

My concern with the Original is the open time being 4-6 minutes, but Gorilla Glue is at least double that. Being my first attempt at building a subwoofer, I thought I might need more time?

I already have the MDF and no way to get it anywhere to cut it. I have a circular saw, which is going to have to do.

The titebond is superb, I am a carpenter and this is what i would use. Also i would go with a double baffle, and i did a double layer of 3/4" and 1/2" mdf all round on my build. I used valchromat mdf which is very dense but a bit pricey. Maybe a bit excessive but they are super solid. 1 litre of the titebond will do you. you can check out my build thread if you like.
p.s If your not very confident cutting the material you could get the whole lot cut on a cnc machine, (not expensive)
 
Last edited:

john01707

Active Member
Ahh yes the original. i'm sure youll be fine. Put it together dry first so you feel comfortable, make sure you have plenty of cramps etc . have all the screw holes pre drilled and countersunk and of you go!
 

MaxeII

Active Member
Ahh yes the original. i'm sure youll be fine. Put it together dry first so you feel comfortable, make sure you have plenty of cramps etc . have all the screw holes pre drilled and countersunk and of you go!
I don't have clamps big enough, so was intending to glue and screw.
 

john01707

Active Member
Thats fine, you can also go round the sub with ratchet straps. this gives you an equal ammount of pressure on all 4 corners, if you do this just put some protection on the corners to protect the mdf.
 

MaxeII

Active Member
Thats fine, you can also go round the sub with ratchet straps. this gives you an equal ammount of pressure on all 4 corners, if you do this just put some protection on the corners to protect the mdf.
I thought that by screwing, I could avoid the cost of buying longer clamps or straps, as I don't think I'm likely to need them ever again. So if I use clamps or straps do I really need to bother with screws?

Would these be good enough?

Or am I better off just getting some longer clamps?
 
Last edited:

MaxeII

Active Member
Can someone please help me understand the possibilities with DSP and EQ'ing. I'll have a Behringer with DSP and DIRAC for the final calibration.
Looking at the attached graph. Am I right in thinking that I will be able to flatten the response from 10Hz to 120Hz at 105dB?
I know there will be some dips and spikes in the real response, but am I right otherwise? I feel daft asking, but I just want to be sure I've got it right.
Can anyone help with this please? As I'm having second thoughts about my whole plan.
 

simonb3665

Active Member
The Behringer has enough filters to shape the response as desired. The only issue is it only goes down to 20hz but you could put a wide q filter on at 20 or a low pass filter which will effectively boost frequencies sub 20. Your in-room response will not look like the graph, it will be shaped by the room as much as the type of subwoofer. The theory is the response should be flatter with 2 subs rather than one. Do you get a flatish response with your current sub?
 

MemX

Well-known Member
I can't comment on the technical side of things as I've yet to brave EQing mine properly (bar Audyssey doing its stuff!) but don't forget you should get room gain at the lower end, which should lift the curve and hopefully mean you can EQ to a level higher than 105dB across the range.

As mentioned above, the room plays a big part so I wouldn't stress until its in and running!
 

MaxeII

Active Member
The Behringer has enough filters to shape the response as desired. The only issue is it only goes down to 20hz but you could put a wide q filter on at 20 or a low pass filter which will effectively boost frequencies sub 20. Your in-room response will not look like the graph, it will be shaped by the room as much as the type of subwoofer. The theory is the response should be flatter with 2 subs rather than one. Do you get a flatish response with your current sub?
So I can do either of those with the NX3000D? As I've never had to apply filters manually before.
I do understand that the in-room measurement will dip and spike. DIRAC usually takes care of most of that.

I thought it was a all fine until I read this:

I thought I was doing the right thing by aiming to produce a response which I will cut and try not to boost, but it seems like I might be buggered either way. I'm currently between a decision of having roughly 12dB to cut for 2 subwoofers or roughly 24dB for 4 subwoofers.
 

MaxeII

Active Member
I can't comment on the technical side of things as I've yet to brave EQing mine properly (bar Audyssey doing its stuff!) but don't forget you should get room gain at the lower end, which should lift the curve and hopefully mean you can EQ to a level higher than 105dB across the range.

As mentioned above, the room plays a big part so I wouldn't stress until its in and running!
I've added a filter in WinISD to account for room gain and multiple subwoofers.
There is something I really need to work out now, before I go any further.
Which is, will I be content with the red line or is that green line where I need to be?
 

Attachments

  • 2or4.jpg
    2or4.jpg
    72.5 KB · Views: 19

MemX

Well-known Member
IIRC 'Reference' for the subwoofer channel on Dolby(?) film levels should allow 120dB (perhaps a bit more?) reproduction - I am totally hazy now on where I read that but I recall bossobass on either AVS or Data-bass saying the dragon crash in How to Train Your Dragon called for something like 126dB at low single-digit Hz :eek: lol

Anyway, I think my point is that 105dB is perhaps a bit light if going for full-on Reference capability, if that is your aim?

But subwoofer output is (again, IIRC) boosted by 12dB/Octave below about 40Hz (or wherever one's room starts to see constructive interference (because the length of the waves exceed the length of the room??) so the dips at the bottom end of the output can be offset somewhat in-room :)

(On that basis, I'm not sure the 'room gain' filter you've applied would be correct??)


This is all very fuzzy and I'm having a caffeine-free weekend as well :D so I'd wait for someone better to comfirm! Perhaps @mattkhan!
 

MaxeII

Active Member
My understanding of Reference Level is 85dB with 20dB headroom for speakers and 85dB with 30dB headroom for subwoofers.

I reckon I'm probably 10dB below reference, which is why I was referring to 105dB. But I don't necessarily need flat to 10Hz to be honest.

But I think I may have misunderstood room gain.
 

mattkhan

Distinguished Member
these things are much easier to work out when you have some subs to experiment with in your room so if you don't have any right now, just build a pair and move on from there
 

simonb3665

Active Member
I had a very quick look at the link. I think that's just saying boost is the same as cutting. So if you cut via eq you will turn the gain to the subwoofer as a whole up so end up with the same amount of strain or headroom whichever way you do it. ie use lots of cuts and you just click the gain control on the Behringer up a couple of notches, use a boost and click gain down a few notches.
In my room, subs have measured about 7 db higher at 20hz corner loaded in room (4x5) at the main listening position than the winisd measurement indicated.
Reference for lfe is 115db and if crossing the bass over from the speakers (as you will) then takes it to a theoretical peak burst of over 120.
I think you will be fine. The kk in the measurements you referenced had hit 97 at 20hz in room (at great low distortion though). If that sub was adequate then I wouldn't worry too much about theoretical reference output.
If you already have the amp/drivers and mdf isn't it worth just finishing off? Unless a rethink means you are still able to return it all?
 

MaxeII

Active Member
I've only really got one shot at this and I'm having a major "what if?" moment.

My decision is to either go ahead with the HF drivers or switch to the HO drivers. The HF would be in 82l enclosures and the HO in 45l enclosures.

If I build 2x 82l subs I have nowhere to go from there, unless I completely start over. If I start with 2x 45l subs, at least I have the option to double up and have 2 dual stacks.

I do still wonder if the 2xHF would actually be more than enough, especially as they seem like they are the slightly better driver for lower distortion and detail. By how much remains mystery.

Also, I've realised that an 82l enclosure is going to be quite a weight and I ain't getting any younger!!!

So on the graph, the red line is 2xHF, the blue line is 2xHO and the green line if 4xHO.
(without any estimated room gain)

Will all that in mind, what would you do?
 

Attachments

  • 2or4.jpg
    2or4.jpg
    86.7 KB · Views: 22
Last edited:

simonb3665

Active Member
I was surprised you went for the hf range but that doesn't mean it wasn't the right choice. Drivers optimised for smaller volumes are less efficient which is fine if space is not an issue at all. The ho handles more power to overcome this. I doubt you would have picked the ho in 45l from the hf in 80l in a blind test once eq'd.
Is swapping drivers a possibility? If it's going to be difficult I would be tempted to push on and do a t least one cabinet and see how it sounds.
 

The latest video from AVForums

AVForums Movies Podcast: Which is the best decade for horror movies?
Subscribe to our YouTube channel

Latest News

Hisense TVs get Disney+ on VIDAA smart OS
  • By Andy Bassett
  • Published
Astell&Kern launches entry level SR25 MKII portable music player
  • By Andy Bassett
  • Published
LG rumoured to release 97-inch OLED TV in 2022
  • By Andy Bassett
  • Published
What's new on Blu-ray (UK) for Halloween 2021
  • By Mark Costello
  • Published
AVForums Movies Podcast: 20th October 2021
  • By Phil Hinton
  • Published

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom