ThanksHi there lightwave and interested DBers.
I have built DBs based on the fostex design (127) and used different drivers in them as an experiment, overall the DBs work really well, in fact far better than I thought possible.
I have no program for simming and I don't even have the parameters for the drivers I used, they were cheap, but I managed to get there eventually, there are of course many variables, bottom and top chamber size, internal port length/diameter and the bottom port.
Basically I just experimented with everything in sacrificial boxes, in other words i didn't care how trashed the boxes got as they were just prototypes.
So heres an idea make a basic pair of boxes that are larger than you think you'll need and make sure the divider inside the box is not fixed so you can move it up or down, if you make the fit tight enough it should hold for experimenting.
The bottom chamber can be adjusted by using blocks of wood or other solid regular shaped objects or even sand in known quantities. Ports can be adjusted by using cardbaord tubes that can be cut at will.
Try a top port dia of 65mm or so and 60mm lenght, though you will likely not finish with this and adjust the top chamber until the mids/highs sound right, then adjust the volume of the bottom chamber until you start to get some bass happening with a shortish bottom port tube (say 60mm by 60mm), then you can start tuning port lenghts, but don't tune the top one too low say around 100hz or so.
To make it work you will need a CD with some tone sweeps or test tones on it at everything from 20hz through to say 16khz.
I know none of this sounds really scientific, but it will work if you persevere and you will probably end learning a heap about how port lenght and cab size effects the sound.
OH and there are other things that I imagine most simms don't take into account that you can play with too, like distance from the walls/corners, height from the floor, the resonance of the cabs, the type of stuffing you use in the cab, mods to drivers and much more, all these things can have big time effects on the sound IMHO and are likely hard to predict via programs alone.
Go ahead have a play with some cheap drivers and cabs, you have little to lose and a heap to gain.
Programs would I'm sure help a lot in terms of cutting down the time involved and I really admire the guys who have created them, but in the end I'd say they would land you in the ball park and theres no guarentee you will like the way they sound without fine tuning anyway, after all what you and I think sounds good is pretty personal.
Hope it helps.
I have built DBs based on the fostex design (127) and used different drivers in them as an experiment, overall the DBs work really well, in fact far better than I thought possible.
I have no program for simming and I don't even have the parameters for the drivers I used, they were cheap, but I managed to get there eventually, there are of course many variables, bottom and top chamber size, internal port length/diameter and the bottom port.
Basically I just experimented with everything in sacrificial boxes, in other words i didn't care how trashed the boxes got as they were just prototypes.
So heres an idea make a basic pair of boxes that are larger than you think you'll need and make sure the divider inside the box is not fixed so you can move it up or down, if you make the fit tight enough it should hold for experimenting.
The bottom chamber can be adjusted by using blocks of wood or other solid regular shaped objects or even sand in known quantities. Ports can be adjusted by using cardbaord tubes that can be cut at will.
Try a top port dia of 65mm or so and 60mm lenght, though you will likely not finish with this and adjust the top chamber until the mids/highs sound right, then adjust the volume of the bottom chamber until you start to get some bass happening with a shortish bottom port tube (say 60mm by 60mm), then you can start tuning port lenghts, but don't tune the top one too low say around 100hz or so.
To make it work you will need a CD with some tone sweeps or test tones on it at everything from 20hz through to say 16khz.
I know none of this sounds really scientific, but it will work if you persevere and you will probably end learning a heap about how port lenght and cab size effects the sound.
OH and there are other things that I imagine most simms don't take into account that you can play with too, like distance from the walls/corners, height from the floor, the resonance of the cabs, the type of stuffing you use in the cab, mods to drivers and much more, all these things can have big time effects on the sound IMHO and are likely hard to predict via programs alone.
Go ahead have a play with some cheap drivers and cabs, you have little to lose and a heap to gain.
Programs would I'm sure help a lot in terms of cutting down the time involved and I really admire the guys who have created them, but in the end I'd say they would land you in the ball park and theres no guarentee you will like the way they sound without fine tuning anyway, after all what you and I think sounds good is pretty personal.
Hope it helps.
Hello,
I just now discovered this thread, I am glad that some other members also achived unusaly good bass response with DBR. It seems that I accidently made DBR, increasing the volume of my stock hybrid speaker, last week I posted the topic under the speaker page: Apogee C/M mod – what I ended with
http://www.diyaudio.com/forums/showthread.php?s=&threadid=83867
I am still curious, how astonishing bass performance achived with 6,5 inch driver.
Best regards
I just now discovered this thread, I am glad that some other members also achived unusaly good bass response with DBR. It seems that I accidently made DBR, increasing the volume of my stock hybrid speaker, last week I posted the topic under the speaker page: Apogee C/M mod – what I ended with
http://www.diyaudio.com/forums/showthread.php?s=&threadid=83867
I am still curious, how astonishing bass performance achived with 6,5 inch driver.
Best regards
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