soongsc said:
No problem
but it could seem like fullrange drivers dont like notches too much...or people are doing it wrong
Eva said:
The ring radiator drivers are OK if they are single diaphragm drivers, but the dual diaphragm coaxials are a disaster. The ring radiators do have a lower output capability but otherwise can be a good choice. Anyways, with the proper phase plug the "path length problem" from an concave dome is not really a problem at all, right?
The diaphagm of a ring will still "break-up" by the way. Just not in the same way as a dome.
But, yes, I like the "idea" of a ring fed into the throat through the center as BMS does. Its very ellegant. Its also about 50 years old. I wonder why it never caught on?
If BMS are made like ScanSpeak ringradiators with a fixed centre with a phaseplug, it does make sense to use it with a waveguide
I reckon that another advantage could be that there is no need fore any actual surround, significant or not
On the other hand, it seems to work much like a "bending wave diaphragm" not unlike a Manger, which has its own flaws
I reckon that another advantage could be that there is no need fore any actual surround, significant or not
On the other hand, it seems to work much like a "bending wave diaphragm" not unlike a Manger, which has its own flaws
Hi,
I am curious to know why the BMS coaxials are a disaster. Could you kindly explain? Are there better choices for a large format speaker like the Tannoy VQ?
Thanks,
I am curious to know why the BMS coaxials are a disaster. Could you kindly explain? Are there better choices for a large format speaker like the Tannoy VQ?
Thanks,
Its at the crossover frequency. The wavefronts change in complex ways and the polar responses get pretty bad. This happens at a critical point in frequency for audibility. On a plane wave tube or on axis things are not so bad, but off axis the responses are not at all under control.
The polar response in the crossover region is 100% dependent on how the inherent group delay of each driver plus the group delay from the crossover is handled. If it is not compensated and matched properly, excess lobing arises, and off-axis radiation may easily be stronger than on-axis for some frequencies, which is a very undesirable situation.
This happens with separate midranges and tweeters too but is probably worse with coaxials.
This happens with separate midranges and tweeters too but is probably worse with coaxials.
Eva said:
I'm sorry, but this is simply not true. Your statement implies that the amplitude response has no effect - really!? The crossover problem is one of the complex sum of two sources. Group delay, phase, amplitude they are ALL factors.
The individual amplitude produced by each source does not matter for polar response, only group delay matching does. When you correct group delay you usually end up with the wrong amplitude response, usually with dips, but global equalization can make it flat again without disturbing polar response.
No electrical equalization can correct polar response - this is fundamental. Polar response is a three dimensional problem and electrical EQ is one dimensional. No one dimensional solution can correct a three diimensional problem.
You probably mean that you can't conceive how to do it, but you can even aim the sweet spot of the crossover overlap regions at the listening height (or the nulls at the ceiling and floor) with a few parametric EQs. Remember that parametric EQs with gain introduce positive group delay while the ones with attenuation result in negative group delay. Once there are two sound sources (like a midrange and a tweeter), electrical EQ becomes a two dimensional solution, each driver has its own EQ.
I'm sorry Eva, but you just don't seem to get it.
Lets say that I have a dip on axis from the crossover, but it does not exist off-axis (a perfectly reasonable situation). If I EQ the axial points with any type of EQ at all, the off axis points will become too high and there will now be a peak in the off-axis points and the power response. There is no electrical EQ that can be done that will correct this situation.
Lets say that I have a dip on axis from the crossover, but it does not exist off-axis (a perfectly reasonable situation). If I EQ the axial points with any type of EQ at all, the off axis points will become too high and there will now be a peak in the off-axis points and the power response. There is no electrical EQ that can be done that will correct this situation.
I somehow get a feeling that Eva is talking about two drivers and gedlee is taling about one.
We are all referring to the BMS 4590/2/4/5 coaxial compression drivers of course.
Thank you for your answers - please feel free to add any more 😀
Thank you for your answers - please feel free to add any more 😀
Eva said:
No, obviously not referring to the coax drivers
And they may not be desireable fore the reason Earl has mentioned...less than ideal loading in a waveguide made fore a 2" mid section
Maybe thats the reason fore the ragged response seen on the tweeter section of the coaxes ?
Well, if both are talking about the interaction between two drivers, I think Eva has a valid point even though it might be tricky to do. There are filters that alter group delay in a limited frequency range without changing the amplitude response.