The MemX DIY procrastination thread - 4 SI18s in 11 cubic feet?

I had thought about that - the antimode only really applies cuts, doesn't it? So the MiniDSP would be better? Or am I going mad?? :eek: lol

I guess the other option might be a Bassis but they're not very cheap (although about the same secondhand as the MiniDSP is new, I think??) and they look hard to set up!!

To start with I may just see how it sounds with the 818's XT32 and room gain (fingers crossed) but it would be nice to see how flat and how low I can get it (although I will need to sort out a laptop and REW if I do that).
 
If you want do apply an LT then a mini DSP is the obvious choice

Linkwitz Transform | MiniDSP

There is an excel spreadsheet that calculates the values to plug in for you so it should be pretty easy to do (assuming you have rew going). If you want to measure that low though you will need a decent calibrated mic.
 
Oh, cool, cheers! :)

I fear I am going to have to shell out for a mic and laptop so I can tweak... :facepalm: lol
 
Oh, cool, cheers! :)

I fear I am going to have to shell out for a mic and laptop so I can tweak... :facepalm: lol

I've got a Umik-1 sat here gathering dust. Don't want to sell it, but welcome to borrow it when the time comes.
 
That's a very kind offer, thank you! :thumbsup:
 
Right, well, yet more procrastination from me... ;) :laugh:


There was a recent post on here that linked through to a couple of posts on AVS that brought up the potential for fried drivers using around the rated power, which has re-raised my worries around using the full 5000w of the amp, which would be double the rated power into each!

(The tests that killed them were crazy <5Hz test tracks for sustained periods, but there was a post a little later from someone saying that others had told him they'd killed them on 'normal' audio material.)


Rather than running two off each channel (so 1250w each) I could instead run all four drivers off one channel, which would give them 625w each (the same as carp on AVS, I think).

The difference in output would be around 3dB less as it's half the power, but would I notice that 3db??


Going from the graphs above (because the lower power graphs are on the other computer and I can't upload them from here), output would be 106dB at 10Hz and 118dB at 20Hz, excluding any room gain. My room is 20ft long, which I think means room gain starts around 28Hz, so I should be getting some reasonable room gain by that point.

Even excluding room gain, would those figures be enough?? Would 109dB at 10Hz and 121dB at 20Hz really make that much difference?

:eek:
 
it will be enough im sure :)
 
just use them and you will be fine, even at reference volume you will be fine there should be no issues of over driving these drivers, don't worry about burning them out, the only people that do this are people using sine waves or ported boxes with no hpf.
 
Thanks for the words of comfort, chaps :)

As you say, I'm sure all will be fine, I'm just worried about watching something at reference like Olympus Has Fallen with 20-30 seconds of sub-10Hz content - it might be a bit much if I'm running them with 1250w each!

I will need to work out if I could wire them so they can be one box per channel or have both boxes daisy-chained onto one channel.... I guess I could have one 'in' speakon and one 'out' speakon!
 
Don't worry about it mate your worrying about nothing.
and regards the power the way the driver is designed it will resist the load of the amp so you will be fine.
This is why some driver offer upgrade options like fi do and they will take an extra 500w RMS.

I had One of my drivers the other day running of my amp in bridged mode which is 2800w RMS just to see if it would give anymore than running unbridged 900w RMS and there was no difference and I played at reference volume with the big bass hitter like clover field and war of and more.
 
Did you have the same setting on the amp in bridged mode and using the one channel , around the 10oclock mk.
 
I left the gain at 9 and it set the sub trim at - 6.

Compared to normal
9 and -2
 
So bridge gives slightly more output.
It's hard to say because remember the dial on the front is gain so if I put say sp4 15 on it in my box it would give the max RMS it can do in bridged.

The be ringer nu3000 was set at 2 and 0 on the trim in bridged mode.
 
Do you think that's down to a power difference having more power or a sensitivity between amps issue.
 
Well the cv2800 has more power bridged for sure. It could be sensitivity of the amp, also are the gain structure could be different and also some amps have selectable voltage inputs.

So I think there's a few things it could be.

It's like I had my as driver on the nu3000 and if I left it all the same and just changed my driver over to my audiobahn the SPL would be the same and I could turn it up to the same volume, the thing is my as needs 750w and the audiobahn only 150w.
 
Don't worry about it mate your worrying about nothing.
and regards the power the way the driver is designed it will resist the load of the amp so you will be fine.
This is why some driver offer upgrade options like fi do and they will take an extra 500w RMS.

I had One of my drivers the other day running of my amp in bridged mode which is 2800w RMS just to see if it would give anymore than running unbridged 900w RMS and there was no difference and I played at reference volume with the big bass hitter like clover field and war of and more.
Brave! lol :D

I will spend some time thinking about speaker wiring options and take it from there :)
 
Brave! lol :D

I will spend some time thinking about speaker wiring options and take it from there :)
it started with my issues of not having enough power from other amps first, I had the nu1000 which was suppose to be 800wrms but when I pushed the as driver hard it caused bad clipping and the driver popped, and running my audiobahn on it was not no better than my 150w RMS plate amp,

As I said I have no hpf of nothing on mine and I push them hard, russel said with his pair he could run them +6hot at reference volume and the amp would just start to clip.

So I'm sure with yours you will be fine.

The octagon set up at gecko must be about 105db at 4hz in room.
Mine will do 105db to 10hz.
 
Rather than running two off each channel (so 1250w each) I could instead run all four drivers off one channel, which would give them 625w each (the same as carp on AVS, I think).

The difference in output would be around 3dB less as it's half the power, but would I notice that 3db??


Going from the graphs above (because the lower power graphs are on the other computer and I can't upload them from here), output would be 106dB at 10Hz and 118dB at 20Hz, excluding any room gain. My room is 20ft long, which I think means room gain starts around 28Hz, so I should be getting some reasonable room gain by that point.

Even excluding room gain, would those figures be enough?? Would 109dB at 10Hz and 121dB at 20Hz really make that much difference?

:eek:
Well, I realised I am an idiot - I can't wire four D2 drivers to show 2Ohm to a single amp channel, only 4Ohm or 0.25Ohm, if I'm correct! :facepalm: :laugh:

And the 4Ohm stereo output per channel of the CV5000 is 1800wRMS IIRC, so I'd only give them 450wRMS each, which wouldn't really be enough, so I will have to go with two drivers per channel to show 2Ohm and sort out the LT as planned!

I'm such a muppet :laugh: lol

I think my brain has shut down for Christmas!
 
So you have 4 dual 2 ohm driver's which will wire as 4 ohm and use in bridged 4 ohm mode.
 
Well, I realised I am an idiot - I can't wire four D2 drivers to show 2Ohm to a single amp channel, only 4Ohm or 0.25Ohm, if I'm correct! :facepalm: :laugh:

And the 4Ohm stereo output per channel of the CV5000 is 1800wRMS IIRC, so I'd only give them 450wRMS each, which wouldn't really be enough, so I will have to go with two drivers per channel to show 2Ohm and sort out the LT as planned!

I'm such a muppet :laugh: lol

I think my brain has shut down for Christmas!

Are the D2 2ohm each or 1ohm? If 2ohm each then I think you could do it:

If you wire two D2 in series which will give 4ohms and repeat, then wire the two lots of 4ohms in parallel to give you 2ohms. Like this If it makes sense:

D2(1)+D2(2)

D2(3)+D2(4)
 

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