Hi Thanks for reading Would an 8" driver be okay to get down to 300hz in an open baffle design
I have an active sub, highest crossover frequency it allows is 120hz @ 12db/octave. With the fall off i can probably get up to 300hz, then use open baffle for everything above that
Also a qts of 0.7 is usually recomended for OB, would higher qts make a driver more suitable for OB, I've seen drivers with qts of 1.2
I have an active sub, highest crossover frequency it allows is 120hz @ 12db/octave. With the fall off i can probably get up to 300hz, then use open baffle for everything above that
Also a qts of 0.7 is usually recomended for OB, would higher qts make a driver more suitable for OB, I've seen drivers with qts of 1.2
It depends on the required output and baffle width (and xmax). I would guess it is fine.
A high Qts reduces the amount of equalization that is required. As you would probably need equalization anyway, the value Qts is not that important.
A high Qts reduces the amount of equalization that is required. As you would probably need equalization anyway, the value Qts is not that important.
Thanks. I'll go with an 8" driver if you feel that is okay for 300hz. Can you give me any recommendations for this driver. I have a budget of £200 per driver, will need to be 4 ohms.
You need a high qts driver for that, maybe a Visaton WS20E or a Monacor SPP200 may fit your needs. But i have no experience with both of them.
This kind of drivers are not made a lot because not many use them. They are a very one trick pony. A high qts makes it very hard to make a box for them, so only usefull in OB or open back speakers. They do give bass in that cocnfig, they don't need a cabinet for that. But don't expect a high volume as xmax is limited with this kind of drivers.
This kind of drivers are not made a lot because not many use them. They are a very one trick pony. A high qts makes it very hard to make a box for them, so only usefull in OB or open back speakers. They do give bass in that cocnfig, they don't need a cabinet for that. But don't expect a high volume as xmax is limited with this kind of drivers.
I use an Eminence Beta 8a as an open baffle mid. I cross it a bit higher, but it should reach 300 Hz fine. Here's my understanding:
The Qt of the Beta is of little relevance for my (or probably your) application, as 300 Hz is a couple of octaves above the drivers Fs. Qt only affects the driver's output as you approach resonance. As long as the Fs is well below the crossover frequency the driver rolloff is determined almost entirely by the baffle. Qt is mostly important for the lowest driver in the system when you are trying for the deepest bass possible from a dipole driver.
Enlarging the baffle would extend the low range of the driver, at the expense of also lowering the dipole peak and thus lowering the useful upper crossover frequency of the driver. That passes the buck to whatever driver is above it. In my case I use the Beta baffleless, to allow it to play as high as possible making the crossover to the HF driver (an ESS Heil) comfortable. If you are crossing to, say, a 1" dome tweeter thing could get difficult. If you have a 4-5" cone upper mid plus a tweeter above the 8" you can afford a bigger baffle for the 8" to gain some low end.
The lower you want the 8" to play, the less efficient it will be because of the baffle rolloff, and the lower the maximum output will be. I'm driving the Beta with a fairly low powered amp (Modulus 86). By crossing it at 400 Hz, I need less EQ and retain as much efficiency as possible which improves the system headroom. If I had more power I could push it lower, up to the driver's excursion limit.
I find that the free program Basta! is very useful for modeling OB driver LF behavior. You can also overlay your projected OB driver response with that of your sub and get some idea whether they can actually mate well. I suspect you are a bit optimistic there, but that's another story.
So, what driver to use? Since Qt is not an important measure, I would look for:
1) Enough efficiency, excursion and power handling to meet your needs for volume and peak headroom with your given amplifier
2) Smooth, extended behavior at the HF end of the driver's range
You have a pretty healthy budget, but high-efficiency 4 Ohm offerings are limited. Maybe something like a B&C 8NW51 would work? 4 ohm domestic drivers are more common, but depending on your demands for volume you may run into power handling or excursion limits. Modeling the drivers will help guide you decide.
Bill
The Qt of the Beta is of little relevance for my (or probably your) application, as 300 Hz is a couple of octaves above the drivers Fs. Qt only affects the driver's output as you approach resonance. As long as the Fs is well below the crossover frequency the driver rolloff is determined almost entirely by the baffle. Qt is mostly important for the lowest driver in the system when you are trying for the deepest bass possible from a dipole driver.
Enlarging the baffle would extend the low range of the driver, at the expense of also lowering the dipole peak and thus lowering the useful upper crossover frequency of the driver. That passes the buck to whatever driver is above it. In my case I use the Beta baffleless, to allow it to play as high as possible making the crossover to the HF driver (an ESS Heil) comfortable. If you are crossing to, say, a 1" dome tweeter thing could get difficult. If you have a 4-5" cone upper mid plus a tweeter above the 8" you can afford a bigger baffle for the 8" to gain some low end.
The lower you want the 8" to play, the less efficient it will be because of the baffle rolloff, and the lower the maximum output will be. I'm driving the Beta with a fairly low powered amp (Modulus 86). By crossing it at 400 Hz, I need less EQ and retain as much efficiency as possible which improves the system headroom. If I had more power I could push it lower, up to the driver's excursion limit.
I find that the free program Basta! is very useful for modeling OB driver LF behavior. You can also overlay your projected OB driver response with that of your sub and get some idea whether they can actually mate well. I suspect you are a bit optimistic there, but that's another story.
So, what driver to use? Since Qt is not an important measure, I would look for:
1) Enough efficiency, excursion and power handling to meet your needs for volume and peak headroom with your given amplifier
2) Smooth, extended behavior at the HF end of the driver's range
You have a pretty healthy budget, but high-efficiency 4 Ohm offerings are limited. Maybe something like a B&C 8NW51 would work? 4 ohm domestic drivers are more common, but depending on your demands for volume you may run into power handling or excursion limits. Modeling the drivers will help guide you decide.
Bill
Anyone have opinions on the Dayton Audio PS220-8 for open baffle? I'm thinking of using it down to 350hz, so pretty similar to the OP's situation.
https://www.parts-express.com/Dayton-Audio-PS220-8-8-Point-Source-Full-Range-Neo-Driver-295-346?
https://www.parts-express.com/Dayton-Audio-PS220-8-8-Point-Source-Full-Range-Neo-Driver-295-346?
I hope you have a tweeter planned, or the upper treble will suffer without your head in a vise.
I use Visaton for years,never been disappointed with their 8' which goes down to about 30 Hz.No open baffle experience ,though. ..Frank
How about the Eminence 820H for your open baffle application? It is 4 ohms and pretty efficient.
Open baffles give a kind of sound that some people like, because open baffles use reflected sound more than sealed box speakers.
With open baffles the sound bounces off the walls and ceiling giving the impression that the sound is coming from the room, rather than from the speakers, giving a wider kind of sound.
With sealed box the sound more radiates towards the listener so sounds as though the sound is coiming from the speakers themselves
What do you think about placing sealed box speakers on ther backs so that the sound fires up to the ceiling then can bounce around off the walls and mimic the effect of open baffles, or have the speakers inwards facing each other at a 90 degree angle to the listener, again to minic open baffle effect.
Or is this wrong and not how speakers disperse sound
With open baffles the sound bounces off the walls and ceiling giving the impression that the sound is coming from the room, rather than from the speakers, giving a wider kind of sound.
With sealed box the sound more radiates towards the listener so sounds as though the sound is coiming from the speakers themselves
What do you think about placing sealed box speakers on ther backs so that the sound fires up to the ceiling then can bounce around off the walls and mimic the effect of open baffles, or have the speakers inwards facing each other at a 90 degree angle to the listener, again to minic open baffle effect.
Or is this wrong and not how speakers disperse sound
Most of us have opinions.
Mine is that for bass bigger is better and the more of them the better.
Dual 300mm is a good start
Mine is that for bass bigger is better and the more of them the better.
Dual 300mm is a good start
As @lousymusician said, the Q of your 8” is irrelevant because you are using it down to 300Hz not 40Hz.
If you use a 2nd order 300hz high pass on that mid, you can adjust the knee of the curve to get a higher Q (bigger capacitor + smaller inductor) or lower Q (smaller capacitor + bigger inductor) and get whatever rolloff you need. Including a few dB of boost if necessary.
It’s a variation of the same approach I describe here, just with a higher frequency (300hz not 40):
Thread 'Open Baffle Bass Boost: +4 to +7dB w/ Passive Xover, No DSP'
https://www.diyaudio.com/community/...boost-4-to-7db-w-passive-xover-no-dsp.404171/
If you use a 2nd order 300hz high pass on that mid, you can adjust the knee of the curve to get a higher Q (bigger capacitor + smaller inductor) or lower Q (smaller capacitor + bigger inductor) and get whatever rolloff you need. Including a few dB of boost if necessary.
It’s a variation of the same approach I describe here, just with a higher frequency (300hz not 40):
Thread 'Open Baffle Bass Boost: +4 to +7dB w/ Passive Xover, No DSP'
https://www.diyaudio.com/community/...boost-4-to-7db-w-passive-xover-no-dsp.404171/
Thanks ! I was thinking of leaving the mid without a high pass filter, this seems to attenuate the bass response by itself, and being open baffle as well this also seems to attenuate the bass again. What i am thinking about is more of a low pass filter where the upper response of the driver is cut off
Just going back to what i was saying about placing sealed speakers on their backs and facing upwards, which should increase reflected sound, it is doing this but not as good as an open baffle, what i am liking about it is the bass loss does not happen as with open baffle but reflected sound does increase
Just going back to what i was saying about placing sealed speakers on their backs and facing upwards, which should increase reflected sound, it is doing this but not as good as an open baffle, what i am liking about it is the bass loss does not happen as with open baffle but reflected sound does increase