After reading this, I've been thinking, how much does the recording mic alter the original performance? We have no control of it, but would it be worth studying in terms of phase equalization?
Soon, there are some recordings where i am pretty sure phase is correct. Mostly they are single point recordings from the likes of Chesky and MA recordings or for classical some Denons. In a multi mic setup you never know. What i know is that my Microtech Gefell Condenser Lab Mic reverses phase and the Microtech people knew about that.
I promissed to publish the measurement of the Scan wideband in a tube. Sorry for the delay. I was out of the house for some time so i could not make the measurements until now. I have now put the driver in a tube, in this case a simple mineral water bottle. Unfortunately results are not very encouraging. When i want to do a 3 way i have no choice to use a sphere. How i solve the remaining problems where Michael takes about has to be seen. I also decided to use the OX tweeter. It is better behaving as the unmodified VIVA 19mm ceramic tweeter. I could cut back the frontplate but i decided to use it for anther project and i am at the moment not prepared to destroy it.
I promissed to publish the measurement of the Scan wideband in a tube. Sorry for the delay. I was out of the house for some time so i could not make the measurements until now. I have now put the driver in a tube, in this case a simple mineral water bottle. Unfortunately results are not very encouraging. When i want to do a 3 way i have no choice to use a sphere. How i solve the remaining problems where Michael takes about has to be seen. I also decided to use the OX tweeter. It is better behaving as the unmodified VIVA 19mm ceramic tweeter. I could cut back the frontplate but i decided to use it for anther project and i am at the moment not prepared to destroy it.
Attachments
Joachim, based on an article in a Honk Kong magazine many years ago, it seems that having the non-inverting polarity is about 50% chance from brand to brand based on the author's collection of a few thousand CDs. However, I am not referring to polarity, but flattening the phase response of a mic using digital methods as I have done with the speakers. I am curious what difference in recording we would hear if someone did that on the recxording mics.
The mic i am most measuring with is the Girardin mic and that comes with a correction file. The new B&K lab mics also come with a correction file. They could be used for recrding too. I think your idea to use digital equalisation for recording microphones is a good one. Microtech makes a digital microphone ( not really, it is an analog mic with an inbuild AD converter ) and i could ask them if it includes some compensation.
It is definitely above the stop point I use in the UE. I decided to EQ the tweeter only up to 20K. I had gone higher than that, but the DXT is too much to EQ since the breakup changes so quickly off-axis. I felt that the polar response with the uncorrected 20K+ area would likely be better than flat on-axis with the over-equalized off-axis that would occur.
I also have used either 1/6th or 1/12th octave smoothing of the measurements that feed the UE for the same reason, not using excessive on-axis EQ to the detriment in the off-axis. Either one means that the UE EQ of the tweeter will not completely correct the tweeter on-axis, 20K limit or not.
Dave
The offer for the premiminary version expired on the 1st of January. You will have to wait unfil the official release and then decide if you want to purchase the UE.
The crossover that worked best for my case (target) is LR8. I did not maintain the impulse responses from a set of polar measurements I made and I dont' recall how they compared to on-axis, but I do have the polar measurements of the dipole system. To me, the off-axis FR response is good. The drivers are close to being aligned on the design axis, LR8 @1200Hz.
Non-normalized plots:
The tweeter response has been improved and smoother than shown here. These were from 1/6 octave smoothed data. The earlier screen shot from HOLM used only 1/12 smoothing and some additional felt for the 5-10K region.
I could understand how an offset could cause pre-ringing with an Fc with directionality not matching up between drivers in the crossover area, but in the case shown and through listening, the LR8 holds up rather well, IMO.
It may be the case that since the UE corrects amplitude and phase of each driver individually that the overall response off-axis is an improvement over previous DSP implementations. Just some speculation on my part.
Dave
Last edited:
The crossover that worked best for my case (target) is LR8. I did not maintain the impulse responses from a set of polar measurements I made and I dont' recall how they compared to on-axis, but I do have the polar measurements of the dipole system. To me, the off-axis FR response is good. The drivers are close to being aligned on the design axis, LR8 @1200Hz.
Non-normalized plots:
The tweeter response has been improved and smoother than shown here. These were from 1/6 octave smoothed data. The earlier screen shot from HOLM used only 1/12 smoothing and some additional felt for the 5-10K region.
I could understand how an offset could cause pre-ringing with an Fc with directionality not matching up between drivers in the crossover area, but in the case shown and through listening, the LR8 holds up rather well, IMO.
It may be the case that since the UE corrects amplitude and phase of each driver individually that the overall response off-axis is an improvement over previous DSP implementations. Just some speculation on my part.
Dave
High Dave,
If the crossover is of the LR type it makes no difference if the phase linearization is done on the individual band passes or on the system. Fo a Butterwoth crossover the linearization must be done on the entire system. I such a case the system will have linear phase but the individual band passes will not.
In the current state of development the UE olny has the capability to linearize each band pass imdividually, thus only LR targets can be used.
It will be no different for the breakup as it is for any other non-linearity in FR. If it's equalized flat, the CSD will be as one would expect for flat FR.
The problem with doing such an EQ is that you should consider what that EQ does to the off-axis response. But for a tweeter above 20K, I'm of the opinion that it doesn't matter much one way or the other for most folks. I doubt that most of us would or could hear the difference above 20K.
Dave
Improving a breakup mode over 20KHz improved the sound quality for Domingo singing. The harshness that occur only at certain notes were greatly reduced. That is my experience. Good thing you don't need to do it.
Note as discussed earlier in this thread, certain EQ methods improve the stored energy situation. Joachim first mentioned his experience, and provided data that shows it. I also showed it using UE. The only issue of the last measurement I did is that I did not go high enough in the measurements to more convincingly reveal whether the breakup mode situation is further improved or not. I think I will just play some more Domingo to at least find out what I hear before I measure again.My concern would be, if I don't hear it, but lots of other people do, then I'm in deep trouble if I cannot find proper measurable way to relate it with what they hear. If I hear it but others don't, then I'm safe.
Maybe with a 20KHz polar like this would be safe to equalize.
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
In Essex we simply used a 44Khz sampling rate so the oil can resonance of the used metal dome tweeter was not exited. Ultra sonic resonances can fold down into the audible range
after a certain amount of time is passed so it is better to avoid them or not exite them i think. Yes, originally this thread was about a passive speaker but the interest in digital equalisation is so high that i think now about a digital equalised version too. Feel free to post about that option too.
after a certain amount of time is passed so it is better to avoid them or not exite them i think. Yes, originally this thread was about a passive speaker but the interest in digital equalisation is so high that i think now about a digital equalised version too. Feel free to post about that option too.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.