I want to use bi-pole woofers on each channel so will be buying four (probably) 15 inch 4 ohm drivers.
But which is the best way to power them? I want to use chip amps so the options seem to be:
A single amp for each driver a la Linkwitz.
Wiring each pair in parallel from one amp. (For an 8 ohm load)
The amp options are 'basic' amp, bridged, parrallel or both.
For simplicity I would prefer the one amp per driver with something like a 3886 chip but welcome any suggestions from those more experienced in these issues.
At present, it looks like the drivers that I will be using have the following T/S parameters:
FS 30Hz
Qts 1.2
Qms 4.55
Qes 1.78
Re 3.8 ohms
But which is the best way to power them? I want to use chip amps so the options seem to be:
A single amp for each driver a la Linkwitz.
Wiring each pair in parallel from one amp. (For an 8 ohm load)
The amp options are 'basic' amp, bridged, parrallel or both.
For simplicity I would prefer the one amp per driver with something like a 3886 chip but welcome any suggestions from those more experienced in these issues.
At present, it looks like the drivers that I will be using have the following T/S parameters:
FS 30Hz
Qts 1.2
Qms 4.55
Qes 1.78
Re 3.8 ohms
Hi Nuuk,
Just a correction. If you wire each pair in parallel you will have a 2 Ohm load not an 8 ohm load, you will have to wire them in series if you want an 8 ohm load.
Regards,
Tony.
Just a correction. If you wire each pair in parallel you will have a 2 Ohm load not an 8 ohm load, you will have to wire them in series if you want an 8 ohm load.
Regards,
Tony.
Thanks Tony - I have been messing around with caps to make up a crossover for the last couple of days and have parallelling caps on the brain. Of course, it should be series to get 8 ohms!
Thanks Dave- just the simple answer that I was hoping for! 🙂 Will the 3886 (well four of them) be up to driving these 15 inch beasties?
Nuuk said:
Should be. I got sufficient levels with a single Shiva and 2x20W out of my NAD 7020... you'll have a lot more gumption than that. I plan of 4 chipamps (~25W each) to drive my 4 Foster 12s in a pr of push-push TLs.
dave
At present the most likely candidates are the 15 inch drivers shown
HERE at CPC
FS 30 Hz, Qts 1.2, and around 34UKP. They are apparently made by Monacor.
how big will be baffle ?????
on floor ?
With a qts like that they should do well.........
I look forward to your progress with this.............
norm
on floor ?
With a qts like that they should do well.........
I look forward to your progress with this.............
norm
Nuuk
These are indeed Monacor drivers but intended for the car use.
You can find them on Monacor website:
15" - SP-382C
12" - SP-302C
10" - SP-252C
All well suitable for open baffle (Qts>0,7 and Fs<40Hz).
The only problem I can see is their 4 ohm nominal impedance.
At least in case of using only one per channel.
Any one has the idea how this driver would behave beeing a part of two way system with 8ohm full range driver for mids and highs.
If the sensitivity is the same in both drivers,would the one be louder becouse it is 4 ohm?
Bartek
These are indeed Monacor drivers but intended for the car use.
You can find them on Monacor website:
15" - SP-382C
12" - SP-302C
10" - SP-252C
All well suitable for open baffle (Qts>0,7 and Fs<40Hz).
The only problem I can see is their 4 ohm nominal impedance.
At least in case of using only one per channel.
Any one has the idea how this driver would behave beeing a part of two way system with 8ohm full range driver for mids and highs.
If the sensitivity is the same in both drivers,would the one be louder becouse it is 4 ohm?
Bartek
Dave,
Maybe you have any idea how connecting 4 ohm driver for the bass with 8 ohm wide range driver for mid /highs would behave?
Bartek
Maybe you have any idea how connecting 4 ohm driver for the bass with 8 ohm wide range driver for mid /highs would behave?
Bartek
zygibajt said:
How high is the XO point... anything below 200 Hz you should be thinking active which makes it a no-care situation.
If you are XOing passively, how you do it becomes somewhat conditional on hoe your amp' output changes from 8 to 4 ohms -- and even then it isn't that simple since there really is no such thing as a 4 or 8 ohm speaker -- the reality is much more complex.
dave
Nuuk said:
A bi-pole open baffle??? I'm having trouble visualizing that... i can see a push-push OB.
dave
I have two Fostex Fe-204 laying around ,and would like to use them and build some speakers.I'm not into full range and back loaded horns,becouse it doesn't go that low and I don't want to build complex enclosure (at least not for these drivers).
I figured I might try OB at the same time.
The only drivers that I found might fit are:
Caire 250 -this one should match ideally with sensitivity
Monacor car drivers -10,12 and 15 inch.
But all of them are 4 ohm.
The crossover freq. will be somewhere between 200 and 500Hz.
I also played with Thorsten's OB calc.
Caire seems to match witch sensitivity perfectly.
And it seems that two monacors per side (12") would work ,too.
But calculators are theory abd I'm afraid I will buy the drivers and i will turn out that there are much louder then Fostex.If Fostex will be louder I cen L-Pad it.
Bartek
I figured I might try OB at the same time.
The only drivers that I found might fit are:
Caire 250 -this one should match ideally with sensitivity
Monacor car drivers -10,12 and 15 inch.
But all of them are 4 ohm.
The crossover freq. will be somewhere between 200 and 500Hz.
I also played with Thorsten's OB calc.
Caire seems to match witch sensitivity perfectly.
And it seems that two monacors per side (12") would work ,too.
But calculators are theory abd I'm afraid I will buy the drivers and i will turn out that there are much louder then Fostex.If Fostex will be louder I cen L-Pad it.
Bartek
Bipole often used for room independent deep bass
Dipoles and bipoles are often used to reduce room effects. Dipoles can reduce side wall reflections compared to standard box monopole speakers, but have less effect when the dimensions of the room approach the length of the deep bass being reproduced. 20 Hz = 56 ft. Bipoles are sometimes used to reduce room resonances for deep bass in a small room by using mirror symmetry to reduce nulls and peaks.
The Martin Logan Statement added a line array of bipole subwoofers to complement their dipole arrays.
My ears say:
Bipole subwoofers help from 16Hz to ~ 40Hz room short dimension frequency when powerful sub-bass is desired. Bipoles are efficient sound pressure devices.
Dipole best 40Hz - 1.2Khz to cover standard orchestra and human voice. Dipoles used above about 200Hz start to create a fake size soundstage, but changing from dipole to monopole pattern in the human voice range is far worse than extending dipole radiation to 1Khz. Dipole radiation above 1Khz creates a very artificially sized sound stage. Dipoles can be used down to 20Hz but require high power and will not do much to reduce room resonances in small rooms. Dipoles are sound velocity devices.
Monopole 1.2Khz - 20Khz
Dipoles and bipoles are often used to reduce room effects. Dipoles can reduce side wall reflections compared to standard box monopole speakers, but have less effect when the dimensions of the room approach the length of the deep bass being reproduced. 20 Hz = 56 ft. Bipoles are sometimes used to reduce room resonances for deep bass in a small room by using mirror symmetry to reduce nulls and peaks.
The Martin Logan Statement added a line array of bipole subwoofers to complement their dipole arrays.
My ears say:
Bipole subwoofers help from 16Hz to ~ 40Hz room short dimension frequency when powerful sub-bass is desired. Bipoles are efficient sound pressure devices.
Dipole best 40Hz - 1.2Khz to cover standard orchestra and human voice. Dipoles used above about 200Hz start to create a fake size soundstage, but changing from dipole to monopole pattern in the human voice range is far worse than extending dipole radiation to 1Khz. Dipole radiation above 1Khz creates a very artificially sized sound stage. Dipoles can be used down to 20Hz but require high power and will not do much to reduce room resonances in small rooms. Dipoles are sound velocity devices.
Monopole 1.2Khz - 20Khz
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