I've attached the simulation using 830845, could someone verify it is correct?
As I said, the pro version would be nice to simulate filters but it doesnt like the numbers I'm using, even with auto calculation.
It's in an 80L Box in the simulation.
The space under my table where (I'll post a picture) I'm going to put the enclosure allows 80 approx Liters or so so going to do that, being the centre of the room should aid the omnidirectional-ity.
14Hz is a tad overkill for me I think, even if at 90dB or so doesn't that just cut through concrete?
Low impedance is needed for circuits apparently (like the Linkwitz I may implement), but is 450mV / 530ohm low enough? (this is the spec for DAC I'm using).
Thanks in advance.
As I said, the pro version would be nice to simulate filters but it doesnt like the numbers I'm using, even with auto calculation.
It's in an 80L Box in the simulation.
The space under my table where (I'll post a picture) I'm going to put the enclosure allows 80 approx Liters or so so going to do that, being the centre of the room should aid the omnidirectional-ity.
14Hz is a tad overkill for me I think, even if at 90dB or so doesn't that just cut through concrete?
Low impedance is needed for circuits apparently (like the Linkwitz I may implement), but is 450mV / 530ohm low enough? (this is the spec for DAC I'm using).
Thanks in advance.
There are instructions online for adding drivers to WinISD Pro. It can be a little picky if the parameters don't match up exactly, but if you follow the instructions, you shouldn't have any trouble.
IIRC (and this is worth double-checking), enter in this order...
Mms
Sd
Fs
Qts
Qms
Xmax
Le
Pe
Chris
IIRC (and this is worth double-checking), enter in this order...
Mms
Sd
Fs
Qts
Qms
Xmax
Le
Pe
Chris
Undecided on ported vs sealed, I think ported is a more natural sounding approach involving air, seeing majority of studios at least in the 80s era I think were ported.
It will be for music playback, some more recent tracks in my list go to 28hz or so, I like that 80s funk / hip hop sound too and have alot of up-beat music like house though I think bpm is not an issue if a sub is powered properly.
The room its for is is about 4 by 5m or so, I think XXL400 from bk would do the trick or save up for monolith (overkill it).
If its cheaper a diy kit would be cool if the result is superior.
Thanks for reading
Ported is always better, although you add a level of difficulty as the Bass Reflex (I suppose that is what you mean by "ported") needs to be precisely calibrated (i.e. diameter and length, position on the box etc.) otherwise you run a chance of cancelling the wave.
Sealed offers less problems, as being, theoretically, the best speaker system; a perfect speaker is a speaker with an infinite front panel separating the cone in two sealed sides.
The best box to make a sub would be a cement pipe with the sub a one end the other end buried into a sand pit -or- a heavy & thick box of lead (like a safe) as it is what you would need to reduce resonance to virtually zero. But that would be OTT IMHO as the human hear and body (at these frequencies) feels more than hears and cannot really "feel" the problem if you make good boxes.
High pass filter at 17-20Hz is required to avoid destroying the drivers, in a sense, like someone said, it will/may also create distortion, but at these frequencies it is induction issues more than all else.
A good box made of "at least" 25mm MDF/Chip board (what was in use in almost all good speakers in the 70-80's0 reinforced by inner supports/columns etc. would be ideal, if you can get solid Oak or whatever hard wood that thick that's even better, inners of speakers must be dampened by foam also. Depending on the size, a good 30-50mm or more thick would be good.
Hope this helps
It does not matter (much) where you stand or sit in a room if you have the correct system
I would go for two 23cm or even 30cm cone in two nice mid-sized boxes (50Wx80Hx45D) [mm], then you seal your 6.5 inch in for your meds and a good tweeter for your highs.
All made in a nice hardwood case. Sealed
Thank you chris for your effort , entering in that order worked a treat;
I will be placing box under the table in middle of room to help omnidirectional effect as previously said.
(Not sure if WinISD accounts driver volume...)
Do I really need a physical EQ? Two reasons I ask this;
Firstly I will be using Room EQ at final stage of integration, which is the equivalent to changing the final curve!
Secondly cabin / room gain (12 dB/oct);
My room is 40Hz. (speed sound / (longest dim. x 2)
It would be unwise to implement a Linkwitz Transform when REW will change curve anyway. I notice WinISD has EQ Transfer function graph, so I could copy that curve into software DSP and get net result.
Any thoughts on this?
, entering in that order worked a treat; I will be placing box under the table in middle of room to help omnidirectional effect as previously said.
(Not sure if WinISD accounts driver volume...)
Do I really need a physical EQ? Two reasons I ask this;
Firstly I will be using Room EQ at final stage of integration, which is the equivalent to changing the final curve!
Secondly cabin / room gain (12 dB/oct);
- ESP
My room is 40Hz. (speed sound / (longest dim. x 2)
It would be unwise to implement a Linkwitz Transform when REW will change curve anyway. I notice WinISD has EQ Transfer function graph, so I could copy that curve into software DSP and get net result.
Any thoughts on this?
This is blatantly untrue.
Ported boxes do weird things in the time domain: it takes half a cycle for the output to build to full-strength, as the first half-cycle is from the front of the driver alone. Not everyone is sensitive to these delays, but those that are will have to use sealed boxes or similar.
Ported boxes are also larger than sealed boxes.
Giro,
You only need to EQ once. If you're already doing some EQ elsewhere, there's no need to implement a Linkwitz Transform.
Rooms are very weird in low frequencies: there may well be a net gain at LF, but I can guarantee there'll be some deep notches too. Room gain isn't something to bank on having when it comes to ensuring headroom, but it is to be taken as welcome if it means you can reduce the power input at certain frequencies.
Also note the assumptions made when the ESP article says there's 12dB/octave. I bet your room meets exactly none of them.
Is it perfectly sealed?
Are all walls, floor, and ceiling perfectly rigid?
That still doesn't look like WinISD Pro...
LinearTeam
Chris
My description is how a ported box works. Done right or not, the low frequency output of a ported box will have time delays when compared to a sealed box. Therefore, we cannot say that a ported box is definitely better.
I think this might be getting off-topic, so feel free to start a thread about ported vs sealed cabinets.
Chris
I think this might be getting off-topic, so feel free to start a thread about ported vs sealed cabinets.
Chris
"It takes half a cycle to build to full strength"
What is this non-sense? First off "half a cycle" is one full compression wave, peaking at !/4 a cycle & going down from there. Time delays would seem to be a non-issue as the cycles of compression & rarefaction are of Thirty-Two foot waves traveling the space.
Port location even at six feet from the driver make a fraction of the distance when 32 feet is in play.
Do you have documentation on this effect? Any double blind listening tests as to this effect?
____________________________________________________Rick........
What is this non-sense? First off "half a cycle" is one full compression wave, peaking at !/4 a cycle & going down from there. Time delays would seem to be a non-issue as the cycles of compression & rarefaction are of Thirty-Two foot waves traveling the space.
Port location even at six feet from the driver make a fraction of the distance when 32 feet is in play.
Do you have documentation on this effect? Any double blind listening tests as to this effect?
____________________________________________________Rick........
Rick,
Cone moves forward, creating a wave of positive pressure that propagates. Inside the cabinet, there is negative pressure.
In order to make use of the negative pressure, its effectively delayed by half a cycle.
When that half a cycle has passed, the cone is moving in the other direction, creating negative pressure. The negative pressure within the cabinet is finally released, and adds to the output from the front of the cone.
I see no reason you've involved wavelengths: Helmholtz resonance doesn't care if its 100Hz or 20Hz.
Chris
Back again ...
Using WinISd calculator as a guide, i'm now looking at parts for HPF.
What did you use to make your filter out of curiosity chris?
I started with 0.1uF caps, which I can find on maplin (LCR Audio-Grade Polypropylene Axial 630V 0.1uF Capacitor)
and "72.343ohm" resistors.
Not sure what OpAmp to use, Wisd suggest "UA741".
Thanks
Using WinISd calculator as a guide, i'm now looking at parts for HPF.
What did you use to make your filter out of curiosity chris?
I started with 0.1uF caps, which I can find on maplin (LCR Audio-Grade Polypropylene Axial 630V 0.1uF Capacitor)
and "72.343ohm" resistors.
Not sure what OpAmp to use, Wisd suggest "UA741".
Thanks
I actually used a Behringer 31-band graphic eq. I dialled in the Linkwitz Transform and used the swept high-pass filter to take out anything below ~15Hz. These days I have a DCX2496, but I'm keeping the graphic around to eliminate mic feedback when I'm using my stereo as a PA system.
TL071, TL072, or TL074 are pretty much the go-to op-amps people use around here. Its possible to better them specs-wise, but not by much, and certainly not at that sort of price.
For components, try cpc.farnell.com
Free next day delivery, and makes Maplin look hideously expensive ('cause it is...).
Chris
PS - you can make that resistor up with a variety of other resistors. Round off to the nearest ohm, and go from there. Its worth buying far more than you need, and using a meter to pick the closest ones. The components are literally pennies, and they'll come in handy the next time you want to do something.
TL071, TL072, or TL074 are pretty much the go-to op-amps people use around here. Its possible to better them specs-wise, but not by much, and certainly not at that sort of price.
For components, try cpc.farnell.com
Free next day delivery, and makes Maplin look hideously expensive ('cause it is...).
Chris
PS - you can make that resistor up with a variety of other resistors. Round off to the nearest ohm, and go from there. Its worth buying far more than you need, and using a meter to pick the closest ones. The components are literally pennies, and they'll come in handy the next time you want to do something.
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