Hi,
the frequency resolution depends on the sampling frequency and the FFT-Length.
Most measurement systems allow to choose multiple values of both, but typically one rather chooses a different sampling frequency.
The relationship is: Fs/2N with Fs= sampling frequency and N=number of FFT.
If You sample at say 4kHz the highest frequency content can be up to 2kHz.
If You now choose a FFT length of 4096 the frequency resolution is 4000/4096, hence 0.9765Hz.
Raising the Fs to 48kHz would increase the frequency resolution to 11.718Hz.
Changing the FFT number to 16384 refines the frequency resolution to 2.929Hz
Since lowering Fs as well as increasing N increases the measurement time interval, one needs to make a sensitive compromise between ´measurement speed´ and frequency resolution.
jauu
Calvin
the frequency resolution depends on the sampling frequency and the FFT-Length.
Most measurement systems allow to choose multiple values of both, but typically one rather chooses a different sampling frequency.
The relationship is: Fs/2N with Fs= sampling frequency and N=number of FFT.
If You sample at say 4kHz the highest frequency content can be up to 2kHz.
If You now choose a FFT length of 4096 the frequency resolution is 4000/4096, hence 0.9765Hz.
Raising the Fs to 48kHz would increase the frequency resolution to 11.718Hz.
Changing the FFT number to 16384 refines the frequency resolution to 2.929Hz
Since lowering Fs as well as increasing N increases the measurement time interval, one needs to make a sensitive compromise between ´measurement speed´ and frequency resolution.
jauu
Calvin
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Thanks for all your reactions!
And thanks Calvin for your comments, it is always helpful to get feedback. I already had some doubts about reliability of my measurements as for instance I don't now how much the mic is contributing to the distortion compared to the loudspeaker.
I have to dig further into this measurement topic as I lack knowledge. I would like to find out about distortion contribution of my mic (UMIK-1) and if I can "subtract" this from the measurement.
Regards
And thanks Calvin for your comments, it is always helpful to get feedback. I already had some doubts about reliability of my measurements as for instance I don't now how much the mic is contributing to the distortion compared to the loudspeaker.
I have to dig further into this measurement topic as I lack knowledge. I would like to find out about distortion contribution of my mic (UMIK-1) and if I can "subtract" this from the measurement.
Regards
The trick is to use good methods such as A-B comparisons rather than relying on the perfection of your tools for absolute readings. Or, seeing if there is a knee in the curve, noting if distortion rises dramatically at some point, and so on. Always good to double-check as much of your measurement system as possible by seeing how a looped-back signals fares.
All the sort of lab procedures you may never learn in school.
B.
Please mind the proximity effect when measuring flat-panel electrostatic loudspeakers from a short distance; when the far-field response is flat, the response at a finite distance will rise with 20 dB per decade below the frequency at which the distance is 1/(2 pi) wavelengths.
Great looking speakers and great looking measurements...bravo!
I'm about to embark on mine as a winter project, I'll be building a set just slightly smaller than your large ones here, so thank you for all of the useful information..
Thank you! That sounds interesing - I would love to see some pictures if they are finished.
Thanks for your kind words. They are not constructed by CNC although I considered this option, that would definitely have saved me time and would have looked better.
I wanted to keep it cheap but in the end it wasn't much cheaper than outsourcing / CNC routing the stators. There are 60 horizontal laths in total (MDF) and these laths have 2 "raw" surfaces that suck a lot of paint. So it took al lot of both time and paint. But the result is aesthetically pleasing, at least to me. But it still has a distinct DIY look.
Thanks again for the information Bolserst, I didn't notice the gap in the Audiostatic transformer
I'm considering to build a (magnetic) woofer to supplement for low frequencies (below 100 Hz). I think it will be a sealed or transmission line woofer. Still not sure, but to me it sounds interesting. I'm wondering if those lower frequencies will add valuable musical information to the overall sound?
An externally hosted image should be here but it was not working when we last tested it.
comparing the Final 0.3 hybrid stats to the new DIY panels (white stat in middle was not connected)
Great looking ESL panels! Yes, no doubt, dynamic woofers will provide information that is not available from the panels alone. Not only for deep bass but also more foundation for, for example, male voices.
Hi thanks for your compliments. These are some photos I made. I used duckttape to stretch the mylar, by drawing a rectangle on both the stretching table (an old door in my case) and on the mylar itself you can measure how it stretches. I think there are also tension measuring devices available that have a hook attached. You can attach a surface and tape the mylar to the surface to measure tension. I didn't built a stretching jig as it takes a lot of time to build. The only limitation of the method I used is limited maximum tension.
The frame is built of MDF, I used +/- 1100 meters of 1,15 mm stator wire.
If you need any specific data or pictures I can post them here.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Just want to say thanks for this post. The above post is one stop shopping for understanding bass quality/response.
Passive crossovers have been a pet peave of mine ever since I built active ones and swapped them out with my super high quality deluxe passive ones (which I also built from a design by Dan Wiggins).
This part of that post is beautiful:
"An inductor consists of a long, thin piece of wire wound into a coil. It has significant resistance. So it will always degrade the damping factor of the system.
This is one of the major reasons that passive crossovers should not even be considered for high performance speakers. Electronic crossovers are far superior because their amplifiers are directly connected to their drivers without any intervening inductors or resistors that ruin the damping factor.
As an aside, I always get a bit of a chuckle when I hear how adamant some audiophiles are about using huge, low-resistance speaker cables when used with passive crossovers. They think they are helping the situation by using a very low resistance cable, but they simply don't realize that they are connecting it to tens of feet of tiny magnet wire that forms an inductor. This eliminates any beneficial effect the large speaker cable might have offered. "
It dose look like the passive crossovers would not work well....but I got say the Electronic Crossovers adds it sound to the setup...ESL are vary unforgiveing...as are full rang Ribbon speakers, like Apogee... after years of trying every setup I could get....ARC tube ,Krell,Apogee Electronic crossovers ....I allways end up back likeing the sound of a passive crossver....
To day I have been reworking a pr of ML CLS esl panels....I got say one res. an one cap..gives some of the best sound I have ever had in 40 years...
Same with wire... what ever one mans thinking is... about it..we cant live with out it.
thanks for your input an findings....
good luck have fun with Audio....
To day I have been reworking a pr of ML CLS esl panels....I got say one res. an one cap..gives some of the best sound I have ever had in 40 years...
Same with wire... what ever one mans thinking is... about it..we cant live with out it.
thanks for your input an findings....
good luck have fun with Audio....
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Unless the speakers on both sides of the crossover are - entirely by accident - within two dB's or so of one another in loudness*, there is no way for a passive crossover to match the two "shelves". If you have good speakers that are pretty flat already, shelving is not something you can readily adjust with DSP/EQ. You need separate amps.
Ben
*OK, nonsense to talk about the loudness of a speaker as if a single number (say, "87dB/1 watt") meant much. But my larger point is that you have to get the two shelves where you want them by ear**, whether or not that corresponds to their spec'ed loudness. Shelf adjustment an't be done, except by lucky chance, without two amps.
**"Gosh, my tweeter seems a bit bright in my room and with my favourite recordings...."
Ben
*OK, nonsense to talk about the loudness of a speaker as if a single number (say, "87dB/1 watt") meant much. But my larger point is that you have to get the two shelves where you want them by ear**, whether or not that corresponds to their spec'ed loudness. Shelf adjustment an't be done, except by lucky chance, without two amps.
**"Gosh, my tweeter seems a bit bright in my room and with my favourite recordings...."
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Thanks for the link to Roger Sanders' comments; very insightful and the man is a great educator.
One question remains for me for which I have never gotten a satisfying answer: what about the resistance of the voice coil in relation to damping?
We discuss damping in terms of speaker cable and amplifier output impedance, and we implicitly consider the back emf source as a voltage source, that is quenched or shorted in varying degrees by the output impedance of the amp in series with the speaker cable impedance. But that back-emf source also has an internal impedance (the voice coil also 'consists of a long, thin piece of wire wound into a coil') and the damping current also must flow through the voice coil. So should we not consider the voice coil impedance in series with the speaker cable and the amp output impedance for the purpose of damping?
Jan
Hi,
the copper resistance of the voice coil has to be taken into the calculation.
It can be summed to the inductor´s, cable´s and amp´s resistance to calculate the ´true´ damping factor, which is the relationship of that sum over the nominal impedance value.
It then quickly becomes obvious that high damping factors of amplifiers are totally irrelevant ... anything beyond a value of 20 is more or less negligable.
A 8R speaker is allowed a minimum impdance of 6.4R (impedance -20%).
So even if any external-to-the-voicecoil resistance were infinitely small the true damping factor couldn´t exceed 1.25
The only parameter where the amp´s and/or a inductor´s resistance counts is amplitude response due to voltage divider action.
Still though imho ESL sound best when properly crossed over with an active Xover.
Passive Xovers waste considerable power since the complete equalisation can only be achieved by attenuation.
This can cost by up to 15dB and also costs on dynamic range.
jauu
Calvin
the copper resistance of the voice coil has to be taken into the calculation.
It can be summed to the inductor´s, cable´s and amp´s resistance to calculate the ´true´ damping factor, which is the relationship of that sum over the nominal impedance value.
It then quickly becomes obvious that high damping factors of amplifiers are totally irrelevant ... anything beyond a value of 20 is more or less negligable.
A 8R speaker is allowed a minimum impdance of 6.4R (impedance -20%).
So even if any external-to-the-voicecoil resistance were infinitely small the true damping factor couldn´t exceed 1.25
The only parameter where the amp´s and/or a inductor´s resistance counts is amplitude response due to voltage divider action.
Still though imho ESL sound best when properly crossed over with an active Xover.
Passive Xovers waste considerable power since the complete equalisation can only be achieved by attenuation.
This can cost by up to 15dB and also costs on dynamic range.
jauu
Calvin
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