I'm still finishing my 2-way MTM project but I'm aldready planning my next project, which would be my first 3-way system.
I've been thinking of a using a open baffle midrange unit in this project. I've never made any ob speakers so I need some help and advices on this one.
I have something like this in my mind:
http://koti.mbnet.fi/twisted-/3way/model.gif
The front baffle would be tilted to compansate the acoustic center differences. I would use a 8" woofer probably in a reflex box. The midrange would be in an open baffle, the lighter gray in the picture is meant to be just a possible side brace (like a small U-frame).
At this moment actual issues would be to choose drivers, think appropriate placements for them in the baffle and chooce approximate xo point.
The woofer and tweeter are the easier ones, the midrange is more difficult. As a woofer I've been thinking maybe Peerless 830868 or 830884. I haven't had much thought with the tweeter, but ScanSpeak D2010 has been in my mind as an option.
I'd like to cross the midrange pretty high, somewhere around 3-5Khz, and midrange/woofer xo point would be around 400-500Hz.
Here's a simulation of Seas MCA15RCY in a baffle described above (without the side braces) as a possible midrange driver:
http://koti.mbnet.fi/twisted-/3way/response.gif
The Qts value is quite low, but if the xo point is around 400-500Hz this wouldn't be a problem, right?
Now questions about the OB that is unclear to me: How does it affect the driver sensitivity? Is the point where the frequency response starts to go down the same point where baffle step happens in a sealed box? above this point, is the sensitivity with OB and sealed box driver the same? If a driver would be set off axis (like in my scetch above) it would cause lobing to other side, is the effect similar with ob driver setup?
Why I've been thinking to cross the woofer/midrange around 400-500Hz is that this is the point where the midrange driver response starts to go down because of the OB. Is this a good idea?
Now about the midrange driver. Above I said that I'd like to cross the midrange/tweeter pretty high. I like the idea that one driver covers most of the midrange. The thing I've been thinking is the off axis response. Now let's take this driver as an example: Seas MCA15RCY. Let's say I would cross this driver at 4Khz. The on axis response is smooth, but the off axis responses are at lower level at this frequency. How does this affect in a open baffle design? Should I choose a driver and xo point where the response is smooth even measured from an angle (in an infinite baffle) or does this make a difference in a ob? If I would use the Seas driver mentioned, would it be more wise to cross it where the off axis is more at the same level, for example 3Khz?
All help, ideas and thoughts are appreciated.
I've been thinking of a using a open baffle midrange unit in this project. I've never made any ob speakers so I need some help and advices on this one.
I have something like this in my mind:
http://koti.mbnet.fi/twisted-/3way/model.gif
The front baffle would be tilted to compansate the acoustic center differences. I would use a 8" woofer probably in a reflex box. The midrange would be in an open baffle, the lighter gray in the picture is meant to be just a possible side brace (like a small U-frame).
At this moment actual issues would be to choose drivers, think appropriate placements for them in the baffle and chooce approximate xo point.
The woofer and tweeter are the easier ones, the midrange is more difficult. As a woofer I've been thinking maybe Peerless 830868 or 830884. I haven't had much thought with the tweeter, but ScanSpeak D2010 has been in my mind as an option.
I'd like to cross the midrange pretty high, somewhere around 3-5Khz, and midrange/woofer xo point would be around 400-500Hz.
Here's a simulation of Seas MCA15RCY in a baffle described above (without the side braces) as a possible midrange driver:
http://koti.mbnet.fi/twisted-/3way/response.gif
The Qts value is quite low, but if the xo point is around 400-500Hz this wouldn't be a problem, right?
Now questions about the OB that is unclear to me: How does it affect the driver sensitivity? Is the point where the frequency response starts to go down the same point where baffle step happens in a sealed box? above this point, is the sensitivity with OB and sealed box driver the same? If a driver would be set off axis (like in my scetch above) it would cause lobing to other side, is the effect similar with ob driver setup?
Why I've been thinking to cross the woofer/midrange around 400-500Hz is that this is the point where the midrange driver response starts to go down because of the OB. Is this a good idea?
Now about the midrange driver. Above I said that I'd like to cross the midrange/tweeter pretty high. I like the idea that one driver covers most of the midrange. The thing I've been thinking is the off axis response. Now let's take this driver as an example: Seas MCA15RCY. Let's say I would cross this driver at 4Khz. The on axis response is smooth, but the off axis responses are at lower level at this frequency. How does this affect in a open baffle design? Should I choose a driver and xo point where the response is smooth even measured from an angle (in an infinite baffle) or does this make a difference in a ob? If I would use the Seas driver mentioned, would it be more wise to cross it where the off axis is more at the same level, for example 3Khz?
All help, ideas and thoughts are appreciated.