guys, again, I really need your advice.
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/207e_enclrev.pdf
fostex fe207e recommended DBR enclosure scheme does not state whether there is a need to fill the enclosures with acoustic filling, although fostex does explicitly recommend the filling in its other schemes for other drivers.
What would be your advice? Would it be better if I filled fostex fe207e DBR enclosure with acousting filling? If yes, how would you advice to do it:
- putting some filling on the bottom of the ecnlosures?
or
- glue some of the acoustic material to the enclosure walls?
or
- both?
the material used for enclosures - plywood 21mm.
Thank you in advance for your help.
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/207e_enclrev.pdf
fostex fe207e recommended DBR enclosure scheme does not state whether there is a need to fill the enclosures with acoustic filling, although fostex does explicitly recommend the filling in its other schemes for other drivers.
What would be your advice? Would it be better if I filled fostex fe207e DBR enclosure with acousting filling? If yes, how would you advice to do it:
- putting some filling on the bottom of the ecnlosures?
or
- glue some of the acoustic material to the enclosure walls?
or
- both?
the material used for enclosures - plywood 21mm.
Thank you in advance for your help.
BSC ...:/
OK, guys, the speakers are done. And, unfortunately, they seem to be kind of shouty and almost bass-less.
The situation fits perfectly into the description on quarter-wave.com website:
"."Leaving the circuit out of the design will result in recessed bass output and an overpowering midrange response
Obviously, the drivers are not yet completely 'burn-in', but I doubt that the situation will drastically improve in time. And I have no option of putting the speakers in the corners.
Sooo...I will try to experiment with BSC. Therefore, I would like to ask you whether this circuit would be suitable for FE207E in DBR enclosure, bearing in mind that it will be driven by t-amp:
http://www.quarter-wave.com/Project05/BSC_Circuit.pdf
Is there anything I should have in mind when making specifically this BSC?
Again, I would appreciate your help.
p.s. I will certainly post the pictures of the speakers later.
OK, guys, the speakers are done. And, unfortunately, they seem to be kind of shouty and almost bass-less.
The situation fits perfectly into the description on quarter-wave.com website:
"."Leaving the circuit out of the design will result in recessed bass output and an overpowering midrange response
Obviously, the drivers are not yet completely 'burn-in', but I doubt that the situation will drastically improve in time. And I have no option of putting the speakers in the corners.
Sooo...I will try to experiment with BSC. Therefore, I would like to ask you whether this circuit would be suitable for FE207E in DBR enclosure, bearing in mind that it will be driven by t-amp:
http://www.quarter-wave.com/Project05/BSC_Circuit.pdf
Is there anything I should have in mind when making specifically this BSC?
Again, I would appreciate your help.
p.s. I will certainly post the pictures of the speakers later.
Try wall placement and/or series resistance (about three ohms to start with). Both of these ought to even out the frequency response to some degree.
My FE207E sounded good the second I fired them up. Certainly not "bass-less". But they are wall-placed and relatively close to the ground, plus I had simmed the response and added the exactly correct amount of series resistance (2 or 3 ohms IIRC) for "max flat" alignment.
http://i68.photobucket.com/albums/i6/heatherandsteve/Projects/0567e9db.jpg
My FE207E sounded good the second I fired them up. Certainly not "bass-less". But they are wall-placed and relatively close to the ground, plus I had simmed the response and added the exactly correct amount of series resistance (2 or 3 ohms IIRC) for "max flat" alignment.
http://i68.photobucket.com/albums/i6/heatherandsteve/Projects/0567e9db.jpg
How does it raise Qes?
I'm trying to understand it from an electrical point of view. It seems like raising the resistance of a speaker would just cause less current to flow to the speaker as the amplifier sees a greater load. But how does that affect frequency response?
I'm not arguing that it doesn't, just trying to understand how.
I'm trying to understand it from an electrical point of view. It seems like raising the resistance of a speaker would just cause less current to flow to the speaker as the amplifier sees a greater load. But how does that affect frequency response?
I'm not arguing that it doesn't, just trying to understand how.
OK, guys, the speakers are done. And, unfortunately, they seem to be kind of shouty and almost bass-less.
Without a notch filter, thats the result. Added series resistance raises the Qes which in turn raises the Qts which in turn changes the FR curve.
The only other way is to have the alingment boost the LF response( several octaves) to where it blends in with IB slope. Even then it may need some BSC or a larger area baffle dependant on the distance from a wall.
ron
Without a notch filter, thats the result. Added series resistance raises the Qes which in turn raises the Qts which in turn changes the FR curve.
The only other way is to have the alingment boost the LF response( several octaves) to where it blends in with IB slope. Even then it may need some BSC or a larger area baffle dependant on the distance from a wall.
ron
For a full range driver with a high BL and a low Qts, adding a resistor in series to simulate raising Qts causes a voltage division between the added resistor and the driver. At system resonance(s), the driver impedance is so large that the voltage drop across the driver is almost not effected by the additional resistor. Low frequency performance is not changed. In reality Qts, or any other Thiele/Small parameter for the driver, is never changed just the signal seen at the input terminals. At higher frequencies the voltage division takes place reducing the signal to the driver. High frequency response is reduced. Efficiency drops a few dB and the overall system SPL is rebalanced, not a rising response anymore. Works great with full range drivers and SS equipment, no compromises if done correctly. The next refinement of this technique is to design a BSC filter.
The only way to know for sure is to try one combination and see how it sounds. Then adjust the amount of attenuation up or down from that point if needed. I never get it perfect with the first attempt and end up adjusting by ear later. If it is only a one or two ohm adjustment, then the inductor probably does not need to be changed. If it is more than an ohm or two, switching to a new inductor would probably be best.
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