I'm not claiming to be an expert, but I believe the reason is to negate the need for Baffle-Step Compensation (BSC). BSC is required because while higher frequencies are directional and project mostly forward from the speaker box, lower frequencies are omni-directional and project both forward and back (start to wrap around the box), meaning that a listener sitting in front of the speakers only hears a proportion of the lower frequencies.
In order to counteract this a baffle-step correction network is used to decrease the high frequencies so that they match up with the low frequencies.
Using a second driver on the back of the speaker box means that as the sound from the front driver decreases in frequency and begins to wrap more around the speaker box, the same is happening from the back driver meaning that they compensate for each other and mean that the overall level of the lower frequencies matches with the upper frequencies.
I am prefectly happy to be corrected if this is badly describes, ill-informed or just plain wrong!!
In order to counteract this a baffle-step correction network is used to decrease the high frequencies so that they match up with the low frequencies.
Using a second driver on the back of the speaker box means that as the sound from the front driver decreases in frequency and begins to wrap more around the speaker box, the same is happening from the back driver meaning that they compensate for each other and mean that the overall level of the lower frequencies matches with the upper frequencies.
I am prefectly happy to be corrected if this is badly describes, ill-informed or just plain wrong!!
Sounds about right, though I never considered that to be the primary intention.
I always thought that is was to created a more omni-directional sound, by reflecting sound to the listener, too (many instruments are fairly omni). With treble that beams a little, having extra treble being reflected would give a more spacious sound.
I always thought that is was to created a more omni-directional sound, by reflecting sound to the listener, too (many instruments are fairly omni). With treble that beams a little, having extra treble being reflected would give a more spacious sound.
another option that eliminates some of the placement issues that a bipole (or dipole for that matter) can create (i.e. relative to rear wall / boundary) is to place second driver on top or side of enclosures
there are numerous examples of commercial and DIY designs with such feature - having build a few of the latter as well as more conventional bipoles, there are many advantages to not having to worry about rear-facing wide-bandwidth drivers.
there are numerous examples of commercial and DIY designs with such feature - having build a few of the latter as well as more conventional bipoles, there are many advantages to not having to worry about rear-facing wide-bandwidth drivers.
double horns
Hello ,
i do it with my double horns:
explained in the middle at:
about what
i did a few constructions all more or less
physically the same:
Saxophon
Trombone
Posaune
Kornett
RDH20
look at my HP, with measurements, feedback, plans
Cornet and RDH20 one of my best constructions.
Hello ,
i do it with my double horns:
explained in the middle at:
about what
i did a few constructions all more or less
physically the same:
Saxophon
Trombone
Posaune
Kornett
RDH20
look at my HP, with measurements, feedback, plans
Cornet and RDH20 one of my best constructions.
I think these questions are pretty much on topic.
Whenever I see a bipolar speaker build one point that is often mentioned is that they sound best when pulled out a bit into the room.
Well I have a very small primary listening room. It's my computer room and all speakers end up there eventually, always in a less than optimal configuration, because of WMA files and internet radio.
I've thought of doubling up my sealed HiVi B3's in a front / top set up so that I can keep them closer to the wall while gaining +3db in volume (driven by an SI T-amp).
If I was to do that, should I .5 one of the drivers?
If so, which one?
R/
Jim
Whenever I see a bipolar speaker build one point that is often mentioned is that they sound best when pulled out a bit into the room.
Well I have a very small primary listening room. It's my computer room and all speakers end up there eventually, always in a less than optimal configuration, because of WMA files and internet radio.
I've thought of doubling up my sealed HiVi B3's in a front / top set up so that I can keep them closer to the wall while gaining +3db in volume (driven by an SI T-amp).
If I was to do that, should I .5 one of the drivers?
If so, which one?
R/
Jim
Be pretty easy to find out what works best once you make them. On ours (that Chris' wife has) they work well with no filters
dave
Quick question...
People seem to always use the same driver for bipoles, thus increasing the cost significantly if one was to use expensive drivers. Double CHR 70s or EL 70s in the Lotus 2 or Metronomes respectively for example.
My question was that if one was to make a speaker with for example an Alpair 10, would it be reasonable to add a upward or rearward firing cheaper driver for ambience such as the aforementioned CHR 70 or EL 70?
Taz.
People seem to always use the same driver for bipoles, thus increasing the cost significantly if one was to use expensive drivers. Double CHR 70s or EL 70s in the Lotus 2 or Metronomes respectively for example.
My question was that if one was to make a speaker with for example an Alpair 10, would it be reasonable to add a upward or rearward firing cheaper driver for ambience such as the aforementioned CHR 70 or EL 70?
Taz.
The system that Dave cites is certainly another example of synergy (or lack thereof) between FR drivers and amp - for the best part of the first year these were driven by a generic Sony stereo receiver (25-30WPC?) and sounded pleasant enough.
But on a whim a few months ago over a long weekend, I dragged a couple of my tube amps (neither with more than approx 1/8th the power of the Sony) into the system, and while I could anticipate the results, my wife's reaction was the big surprise - "oh, honey that's much fuller - you can leave it in" (how often does one hear that after 37yrs together?
)The EL70 certainly has a warmth and texture to its lower mid bass that I personally find missing from the CHR70, and in this particular configuration (second driver upfiring) we found no need for any BSC/EQ or other filtering.
The system that Dave cites is certainly another example of synergy (or lack thereof) between FR drivers and amp - for the best part of the first year these were driven by a generic Sony stereo receiver (25-30WPC?) and sounded pleasant enough.
But on a whim a few months ago over a long weekend, I dragged a couple of my tube amps (neither with more than approx 1/8th the power of the Sony) into the system, and while I could anticipate the results, my wife's reaction was the big surprise - "oh, honey that's much fuller - you can leave it in" (how often does one hear that after 37yrs together?
The EL70 certainly has a warmth and texture to its lower mid bass that I personally find missing from the CHR70, and in this particular configuration (second driver upfiring) we found no need for any BSC/EQ or other filtering.
Uh, wait, did you mean to say the sound was different due to using 4 speakers instead of 2 or because you used a tube amp?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.