Hi Bacon665,
Yes the Mylar did shrink when I used hot air on it. I used 6 micron Mylar.
Wachara C.
Yes the Mylar did shrink when I used hot air on it. I used 6 micron Mylar.
Wachara C.
Hi,
did You actually measure 3.6kV? And where? Air rarely allows for more than 1.5KV/mm to 1.8kV/mm. Higher values result in audible noise.
jauu
Calvin
The manual reads " In bed with Chinsettawong"
....
... and it explains those whitish stains on the diaphragm
(no I haven´t said that....no no)
did You actually measure 3.6kV? And where? Air rarely allows for more than 1.5KV/mm to 1.8kV/mm. Higher values result in audible noise.
jauu
Calvin
The manual reads " In bed with Chinsettawong"
....... and it explains those whitish stains on the diaphragm
(no I haven´t said that....no no)
Hi Calvin,
Well, I don't have a good enough meter to measure. But I'm sure the voltage should be around at that region.
The picture shows the very first time when I tried to bias the diaphragm with 2 mm spacer with around 4.8KV. It was my first try and I had a few problems. Later I changed to use 1.5 mm double sided tape as spacer and bias voltage was reduced to 3.6KV.
Wachara C.
P.S. For your information, I haven't been naughty.
😀
Well, I don't have a good enough meter to measure. But I'm sure the voltage should be around at that region.
The picture shows the very first time when I tried to bias the diaphragm with 2 mm spacer with around 4.8KV. It was my first try and I had a few problems. Later I changed to use 1.5 mm double sided tape as spacer and bias voltage was reduced to 3.6KV.
Wachara C.
P.S. For your information, I haven't been naughty.
😀I have some Acoustat 2+2's that get beamy.
There are separate trannies for the lows and highs
that combine on the outputs and drive each 8 inch wide
panel full range. Would it be possibly more appropriate
to build a narrow panel and stick them between the
8 inch wide panels and feed the panels by the appropriate
tranny? Any idea of the size and spacing to use for high
range panel and if bias should be different?
There are separate trannies for the lows and highs
that combine on the outputs and drive each 8 inch wide
panel full range. Would it be possibly more appropriate
to build a narrow panel and stick them between the
8 inch wide panels and feed the panels by the appropriate
tranny? Any idea of the size and spacing to use for high
range panel and if bias should be different?
Hi Coloradosound,
I have not seen or listened to an Acoustat before. Let's hear from other people.
Wachara C.
I have not seen or listened to an Acoustat before. Let's hear from other people.
Wachara C.
bacon665 said:
Hi Bacon665,
I'm not sure what you meant by switchmode power supply. I just connect to the voltage at any stage that I want to.
Wachara C.
A switch mode uses a step up tranformer to raise voltage (at the cost of current) and then its rectified into dc but this leaves you with pulsed dc so theres a butt load of caps to even out the power supply.
Only thing is i see the caps behind the rectifier...
Only thing is i see the caps behind the rectifier...
Last night I played with a spectrum analyzer software. It's called Audacity. It's a free software running on Mac OSX. I generated a sine wave from 20Hz-20KHz and tried to see how the speakers performed. I tested only the right side speaker and I placed a microphone at around 1 meter away from the speaker. This is one of the results I get. Does it look OK? Please help, because I don't really know what I'm doing here.
Wachara C.
Wachara C.
Hi,
@bacon665
the supply is a simple HV-cascade running on 50Hz (or 60Hz, depending on the power line frequency)
Switch mode power supplies (SMPS) are very different to this.
There are different types of SMPS but basically it works like this:
The power line voltage (230V/50Hz or 115V/60Hz) is rectified and smoothed. Then this dc-voltage is chopped with high frequency by a transistor circuit into small pieces. These pulses pass a transformer that can be much smaller in size than a conventional transformer, because of the high frequency switching. The output voltage is then rectified and smoothed. Depending on the complexity, there can be regultated output voltage(s), protection and overload circuitry, etc. etc.
@coloradosound
There´s no clear yes or no. The two transformer interface is just a smart solution that presents the driving amplifier a more constant load. The radiation pattern though depends on the physical dimensions of the panel, or better on the frequency dependant driven dimensions of the membrane. As Acoustat uses wire stators , it should be rather easy to segment the panels with series resistors similar to the Audiostatic panels. With this technique You reduce the active membrane area with increasing frequency and as such You can control the dispersion and widen it up.
Using a thin strip does basically the same, but You have to cross over the thing and the dispersion pattern shows rather a step than a smooth transition (same problem occurs when crossing over dynamic loudspeaker drivers of different size like 7" bassmid to a 1" dome)
@Chinsettawong
sorry, but You didn´t measure the panel´s frequency response. It rather looks as if You measured the response of Your soundcard.
jauu
Calvin
@bacon665
the supply is a simple HV-cascade running on 50Hz (or 60Hz, depending on the power line frequency)
Switch mode power supplies (SMPS) are very different to this.
There are different types of SMPS but basically it works like this:
The power line voltage (230V/50Hz or 115V/60Hz) is rectified and smoothed. Then this dc-voltage is chopped with high frequency by a transistor circuit into small pieces. These pulses pass a transformer that can be much smaller in size than a conventional transformer, because of the high frequency switching. The output voltage is then rectified and smoothed. Depending on the complexity, there can be regultated output voltage(s), protection and overload circuitry, etc. etc.
@coloradosound
There´s no clear yes or no. The two transformer interface is just a smart solution that presents the driving amplifier a more constant load. The radiation pattern though depends on the physical dimensions of the panel, or better on the frequency dependant driven dimensions of the membrane. As Acoustat uses wire stators , it should be rather easy to segment the panels with series resistors similar to the Audiostatic panels. With this technique You reduce the active membrane area with increasing frequency and as such You can control the dispersion and widen it up.
Using a thin strip does basically the same, but You have to cross over the thing and the dispersion pattern shows rather a step than a smooth transition (same problem occurs when crossing over dynamic loudspeaker drivers of different size like 7" bassmid to a 1" dome)
@Chinsettawong
sorry, but You didn´t measure the panel´s frequency response. It rather looks as if You measured the response of Your soundcard.
jauu
Calvin
Hi Wachara,
I have no idea what you have been measureing, but it's not a speaker response that's for sure. Can you run the program 'ARTA' on a Mac? It's for windows but perhaps you have a emulator/compatibility mode or something? Don't know if that would work.
I have no experience with Audacity but from the short look that I had it does not seem to be capable of doing anything useful regarding speaker measurements. There probably is something usable for the Mac, maybe you can ask in the loudspeakers/loudspeakers forum.
I have no idea what you have been measureing, but it's not a speaker response that's for sure. Can you run the program 'ARTA' on a Mac? It's for windows but perhaps you have a emulator/compatibility mode or something? Don't know if that would work.
I have no experience with Audacity but from the short look that I had it does not seem to be capable of doing anything useful regarding speaker measurements. There probably is something usable for the Mac, maybe you can ask in the loudspeakers/loudspeakers forum.
Hi Calvin and Arend-jan,
I will try to find some other programs that might work. Thanks for your comments.
Wachara C.
I will try to find some other programs that might work. Thanks for your comments.
Wachara C.
Apple & unsupported program
Wachara, setup in the computer the virtual machine for Apple.
In the virtual machine on your computer setup Windows XP or Vista and in Windows XP or Vista setup "SpectraLab" also enjoy.
I can help with search and setup programs in yours Apple
If we shall overcome my linguistic problems 🙂
Yield me yours email
Wachara, setup in the computer the virtual machine for Apple.
In the virtual machine on your computer setup Windows XP or Vista and in Windows XP or Vista setup "SpectraLab" also enjoy.
I can help with search and setup programs in yours Apple
If we shall overcome my linguistic problems 🙂
Yield me yours email
Re: Apple & unsupported program
Hi Kontra,
Thank you very much for your offer to help. I'm trying to understand how to do the measurement, but I have no idea what I'm doing. Anyway, I'll keep trying and if I should need your help, I will let you know.
Wachara C.
Hi Kontra,
Thank you very much for your offer to help. I'm trying to understand how to do the measurement, but I have no idea what I'm doing. Anyway, I'll keep trying and if I should need your help, I will let you know.
Wachara C.
Hi Arend-Jan,
I have just downloaded and installed Arta. I try to a lot of things but I do not seem to be able to get the similar curve you get from measuring the headphone. If you can, please guide me step by step.
Wachara C.
I have just downloaded and installed Arta. I try to a lot of things but I do not seem to be able to get the similar curve you get from measuring the headphone. If you can, please guide me step by step.
Wachara C.
In that image above if he did a frequency sweep and measure the speakers output with a mic then wouldnt that be represent the speakers output curve?
I used Arta to make 2 measurements. The first one is when the microphone is aiming at the 120x25 cm panel.
The second one is when the microphone is aiming at the smaller panel.
Do they make any sense?
Wachara C.
The second one is when the microphone is aiming at the smaller panel.
Do they make any sense?
Wachara C.
Hi Wachara,
Try to put the mic at a distance of 10cm or so, in the middle of the panel you want to measure.
Try to put the mic at a distance of 10cm or so, in the middle of the panel you want to measure.
Ok, here are two more pictures. The measuring distance is at around 10 cm.
The first one is the small one.
Here is the big one.
Wachara C.
The first one is the small one.
Here is the big one.
Wachara C.
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