If I want to add a second driver (the same driver, in series) to a design, would I have to double the effective cabinet volume for the same response? I haven't quite got to grips with designing a cabinet with multiple drivers that share the cabinet volume. Is it simply additive, does one driver bound the others (where there are a mix of ranged drivers) or is there a more complex interaction.
Everything doubles. Imagine 2 enclosures merged together.
And given the drivers are FR, a low pass filter on one may be needed.
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
dave
And given the drivers are FR, a low pass filter on one may be needed.
http://www.planet10-hifi.com/downloads/Dual-Driver-Wiring.pdf
dave
Thanks all. The maths doesn't lie but sometimes there's a serendipitous arrangement that is at odds with the theory and I was kind of hoping for some anecdotal support for it because doubling the volume will be quite difficult to achieve in my case.
@planet10 The link for dual driver wiring is very helpful.
@planet10 The link for dual driver wiring is very helpful.
It's not unusual to see less than double for two. Can you give driver parameters and current volume?
@AllenB This is my first ever design. I've built one pair so far and I'm trying to gauge what improvements I can make:
Mark Audio CHN-50 drivers (pasted from my spreadsheet)
Re 3.4 Ohm
Fs 113.1594 Hz
Sd 0.0028 m2
Vas 1.0965 l
CMS 0.9822 mm/N
MMD 2.002 g
MMS 2.0871 g
Bxl 2.6869 Tm
QMS 2.8318
QES 0.6865
QTS 0.5526
SPL 85.74 dB
Xmax 3.5 mm
Power 7 W
Box volume is 3.4 l
Port length is 74.4mm with an area of 0.8 cm2 (rounded slot)
The reason I started this thread was because I came across some designs based on this driver, one of which is similar in size, but there was a suggestion to stack 2 boxes on top of each other (1 inverted) and wire up the drivers in series.
BTW, these are 3D printed with hollow walls filled with Plaster of Paris mixed with PVA. The front and back are screwed on but there are tenon-type joints to prevent chuffing, and the front & rear panels are stiffened with indents to break up deformation modes. I plan on making some adjustments but one thing I am still really struggling with is the damping material.
Mark Audio CHN-50 drivers (pasted from my spreadsheet)
Re 3.4 Ohm
Fs 113.1594 Hz
Sd 0.0028 m2
Vas 1.0965 l
CMS 0.9822 mm/N
MMD 2.002 g
MMS 2.0871 g
Bxl 2.6869 Tm
QMS 2.8318
QES 0.6865
QTS 0.5526
SPL 85.74 dB
Xmax 3.5 mm
Power 7 W
Box volume is 3.4 l
Port length is 74.4mm with an area of 0.8 cm2 (rounded slot)
The reason I started this thread was because I came across some designs based on this driver, one of which is similar in size, but there was a suggestion to stack 2 boxes on top of each other (1 inverted) and wire up the drivers in series.
BTW, these are 3D printed with hollow walls filled with Plaster of Paris mixed with PVA. The front and back are screwed on but there are tenon-type joints to prevent chuffing, and the front & rear panels are stiffened with indents to break up deformation modes. I plan on making some adjustments but one thing I am still really struggling with is the damping material.
With small full-rangers like these, there are some benefits from running a vertical pair in series - it becomes an 8 ohm load, and you increase the maximum output capability and power handling. The ancestors of the Markaudio drivers - Jordan and Bandor 2" drivers - were often run in vertical pairs. The potential drawback is some combing at high frequencies. You want to minimise that by keeping the drivers as close together as possible. The Markaudio driver frames are large, which makes that tricky.
In many of my designs i can often put the driver in a much smaller box than optimum and still get decent response.
It is all about the compromises you want to make.
Can’t get to my modeler to check your alignment, but i put the CHN-50 into the 2.5 litre miniOnkens as the A52/3.
I would guess that 3.4 litres is too big a box.
As suggested by Ian… 2 series wired with a big cap across 1 (try with and without).
dave
Just playing around (not including box losses), 3.4l might work with 2 drivers.
Whaaaat, have I messed up?! Since I'm stuck with MacOS / Linux, the only tool I could get to work was WinISD and that's the volume that seemed to give the best curve with a small reinforcement at around 85Hz for the port length for 1 driver. I'll have another look but that's an easy print to try although I'll only be able to do one speaker. Could be fun though but I'm all out of the silk purple and I'll have to wait for my big printer to be back in service.
Normally you'd double the area for two drivers. I was aiming for around 90Hz, but these port dimensions are suggesting a low tuning. It wouldn't be a bad thing to double check and to redesign for the best port tuning frequency. With WinISD, check your box losses.
Is it falling before that bump? If yes it is bigger than i’d use.
Allen’s alignmne looks good, i’d tune a bit higher and use a high aspect ratio slot vent to tame the (larger) bump.
dave
If you angle the drivers, either splayed or angled around a vertical axis you'll get better horizontal HF coverage than with one driver.
There is still going to be loping of unpredictable character though, but it might be worth it.
It’s pretty easy to do experiments with two open air drivers playing from 8 Khz and up. Play a constant tone and walk around, preferably outside on a lawn to simulate an anechoic chamber.
There is still going to be loping of unpredictable character though, but it might be worth it.
It’s pretty easy to do experiments with two open air drivers playing from 8 Khz and up. Play a constant tone and walk around, preferably outside on a lawn to simulate an anechoic chamber.