3-way project idea with bipole bass.
Hi folks,
I'm highly tempted to try a bipole bass speaker, due to the following benefits:
1. If frames of the bass speakers get mechanically coupled, little force will get transmitted to the enclosure, so less box coloration.
2. Higher, +6dB sensitivity within the bass range due to the removal of BSC correction network.
Now, my first sequence of priorities at first sight seems to be the following.
1. Choosing side-firing bipole topology instead of front-rear to avoid the "bipole" dip.
2. Back and forth looking for a suitable midrange driver to match the BSC-less bipole bass sensitivity, as well as matching the crossover cut points, where the bass driver's directivity at 90 deg needs to be taken into account. How much headroom, will probably depend of the crossover order. What about time alignment, as the woofers will be farther than the midrange/tweeter configuration?
3. Midrange enclosure. At first I was tempted for an open baffle, but I'm uncertain how a dipole and bipole would match. If you discourage me from the OB way, I'd choose a sealed or dampened closed TL as enclosure.
4. For time alignment perhaps building the midrange/tweeter and bass sections in independent enclosures, then sliding the midrange/tweeter section to the rear. Of course that would bring reflection issues of protruding top edge of the bass section reflecting the midrange waves, but that could be treated with felt or perhaps, designed at 45 degrees?
Hi folks,
I'm highly tempted to try a bipole bass speaker, due to the following benefits:
1. If frames of the bass speakers get mechanically coupled, little force will get transmitted to the enclosure, so less box coloration.
2. Higher, +6dB sensitivity within the bass range due to the removal of BSC correction network.
Now, my first sequence of priorities at first sight seems to be the following.
1. Choosing side-firing bipole topology instead of front-rear to avoid the "bipole" dip.
2. Back and forth looking for a suitable midrange driver to match the BSC-less bipole bass sensitivity, as well as matching the crossover cut points, where the bass driver's directivity at 90 deg needs to be taken into account. How much headroom, will probably depend of the crossover order. What about time alignment, as the woofers will be farther than the midrange/tweeter configuration?
3. Midrange enclosure. At first I was tempted for an open baffle, but I'm uncertain how a dipole and bipole would match. If you discourage me from the OB way, I'd choose a sealed or dampened closed TL as enclosure.
4. For time alignment perhaps building the midrange/tweeter and bass sections in independent enclosures, then sliding the midrange/tweeter section to the rear. Of course that would bring reflection issues of protruding top edge of the bass section reflecting the midrange waves, but that could be treated with felt or perhaps, designed at 45 degrees?
Only if woofers wired in parallel, +3dB from doubling the woofers, +3dB from halving the impedance and ths doubling power delivered.
Not a concern if you cross low enuff.
Keep bass withon a quarter wavelength at the XO and it then all comes down to the XO.
dave
Bipole bass radiation pattern is actually omni, until interference cancellation hits, perhaps at 400Hz.
Omni bass crossed to dipole will be cardioid in xo-range (smoothly 1-2 octaves depending on xo)
So, crossing 150-300Hz LR should work well if yor dipole mid can tolerate it
https://musicanddesign.speakerdesign.net/VariabDF.html
Omni bass crossed to dipole will be cardioid in xo-range (smoothly 1-2 octaves depending on xo)
So, crossing 150-300Hz LR should work well if yor dipole mid can tolerate it
https://musicanddesign.speakerdesign.net/VariabDF.html
Thank you for bumping the thread. I'm still considering on the enclosure type, perhaps an ML-TL bass section is my choice for the moment.
As a midrange driver I'm thinking about a Fostex Fe138-ESR fullrange kept in storage. It has a rated sensitivity of 91.5dB average and can be crossed low enough if necessary Also, the speakers will be designed active, with two amplifier sections. One for the bipole, and another for the midrange - tweeter combo, separated passively.
What have your preference folk for bass ?
open H frame ? up to 200 hz ?
U Frame ? same a little less low end but better impulse response. Good to 200 hz as well ?
Dipole ? Need a huge plan, better impulse response. Good up to ... ?
Ripole ? Cardioid behavior at lower frequency than the above ? Needs eleptical filter and lower cut off ... 100 hz ?
open back folded horn ? Huge....
Sealed, but what about the famous articulation of box less for the higher bass range, circa 60 hz to 150 hz and the lower room mode they give ?
open H frame ? up to 200 hz ?
U Frame ? same a little less low end but better impulse response. Good to 200 hz as well ?
Dipole ? Need a huge plan, better impulse response. Good up to ... ?
Ripole ? Cardioid behavior at lower frequency than the above ? Needs eleptical filter and lower cut off ... 100 hz ?
open back folded horn ? Huge....
Sealed, but what about the famous articulation of box less for the higher bass range, circa 60 hz to 150 hz and the lower room mode they give ?