Good news. I'll have pleanty of power to drive these. The woofer panels will be driven by a QSC PLX2502 amp that is rated at 675 watts into 4 ohms and 1250 watts into 2 ohms. The mid/tweeter panels will be driven by a QSC RMX1450 amp rated at 400 watts into 4 ohms and 700 watts into 2. I'll be using a Beheringer Ultra Drive Pro DCX2496 for the crossover.
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Sweet !!!
They are gonna rock !!!!
Just consider how important the stator coating is otherwise you will never reach there full potential with that kind power behind them.
I know I already mentioned this but I had some where's about 25Kv p-p across the stators with a .075" D/S and no arc through.
This was enough to push the diagphram in to 5% to 10% clipping as measured with a microphone with no amplifier distortion.
That was when I ran them for over an hour like that at about 1% distortion (just starting to flat top) when the panel exploded.he,he,he
It was when I pushed the amplifier as far is it could go and was clipping a little bit at 120V P-P with a 1:256 transformation ratio when it finally gave in.
jer
They are gonna rock !!!!
Just consider how important the stator coating is otherwise you will never reach there full potential with that kind power behind them.
I know I already mentioned this but I had some where's about 25Kv p-p across the stators with a .075" D/S and no arc through.
This was enough to push the diagphram in to 5% to 10% clipping as measured with a microphone with no amplifier distortion.
That was when I ran them for over an hour like that at about 1% distortion (just starting to flat top) when the panel exploded.he,he,he
It was when I pushed the amplifier as far is it could go and was clipping a little bit at 120V P-P with a 1:256 transformation ratio when it finally gave in.
jer
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Qsc Amps Do vare good on the Martinlogans .....CLS...SL3...An the Ascents...I have sead there is match made some where.....ML shoud give them with there speakers....an the sound is sweet....strong amps, i have a old 20years 200ch....gives the Krell a run for it money....With the ESLs.....but the fan...to noise for me, but yours Mybe newer....goodluck
I tested the insulation on the stators using the high voltage module shown in the earlier post. 6800 volts and no arcing, so the powder coating is good. Thats the good news.
I'm still waiting for the .5 mil mylar to arrive for the woofer panels, but I decided to make up the two mid/tweeter panels this morning. I stretched the mylar on my inner tube jig to 1.5% and mounted both of the stator panels onto the mylar. Rubbed the edges with the foam tape along the perimeter and cut the mylar with a razor blade. Flipped the panels over to admire my work, and what do I see, wrinkles. The mylar didn't totally bond to the tape and the tension was released in some spots. So either I got some old 3M tape or I didn't rub down on the panels hard enough before cutting them from the mylar. Thoughts anyone?
I'm still waiting for the .5 mil mylar to arrive for the woofer panels, but I decided to make up the two mid/tweeter panels this morning. I stretched the mylar on my inner tube jig to 1.5% and mounted both of the stator panels onto the mylar. Rubbed the edges with the foam tape along the perimeter and cut the mylar with a razor blade. Flipped the panels over to admire my work, and what do I see, wrinkles
. The mylar didn't totally bond to the tape and the tension was released in some spots. So either I got some old 3M tape or I didn't rub down on the panels hard enough before cutting them from the mylar. Thoughts anyone?
ML panels
What ML dose....There panels a not flat an there are 48 L"x12 W....thay pull from 48"L the top, to the bottem 48"L...Then thay cut the sides...Then put the front panel on...An at the top an bottem thay flip over The panel an tape down 1" on the back side....ML Mylar is coted all over...i had a panel that would not hold a charge an i keep looking an fond the 1" fold of mylar on the back was leaking to the back feed from Setup tranfourmer...cut the Maylar on the back ner the feed
came on works great.....You may have seen these... but for me i need all the help i can get... every pix tells a story...keep up the good work
What ML dose....There panels a not flat an there are 48 L"x12 W....thay pull from 48"L the top, to the bottem 48"L...Then thay cut the sides...Then put the front panel on...An at the top an bottem thay flip over The panel an tape down 1" on the back side....ML Mylar is coted all over...i had a panel that would not hold a charge an i keep looking an fond the 1" fold of mylar on the back was leaking to the back feed from Setup tranfourmer...cut the Maylar on the back ner the feed
came on works great.....You may have seen these... but for me i need all the help i can get... every pix tells a story...keep up the good work
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You might be able to touch them up with a little heat.
Did you wipe down the mylar with solvent to remove any oils before you attached it to the stators?
I use denatured alcohol for this especially before you apply your coating to the Diagphram as well.
jer
No I didn't wipe them down but I will next time. Also, My workshop was only 60*F. Next time I'll run the heat gun around the tape before I lay it on the mylar. Do you think that might help?
Yes, That might work, I had always thought about doing that as well if I ever get the chance to use it.
Right now I like the idea of being able take my panels apart and re-assembling them again.
They do make some super sticky stuff,Maybe Charlie can pop in with the model numbers and where to source it from,as we had researched this last year.
jer
Right now I like the idea of being able take my panels apart and re-assembling them again.
They do make some super sticky stuff,Maybe Charlie can pop in with the model numbers and where to source it from,as we had researched this last year.
jer
On my second attempt, I was successful in streching and bonding the Mylar to my midrange/tweeter panels. But I've decided to make some changes to my plans. I'm now going to go with .120" DS spacing for the midrange/tweeters and I'm going to build a new strecher jig just for the these panels. The streched I'm curently using was built to build two woofer panels at a time and there is way to much waste using it for the two tweeters. With a step up of about 140:1 with 4 toroids, and 6000 to 7000 volts of bias, I should be able to drive the .120" DS spacing to loud enough levels. I just ordered the 3M tape from McMaster-Carr, item number 75935A662.
McMaster-Carr
Lets see how this goes.
McMaster-Carr
Lets see how this goes.
I largest D/S I have used so far is 3/32" and seems to me that all that was required to match the efficiency of a 1/16" D/S was to up the bias voltage.
Although I didn't get to do a complete controlled affirmation on this but at the time I was using an SPL meter and a good ear.
This was back when I first built my larger panels and I would swap out frames of different thicknesses,But I was distracted from the coating not being able to handle the higher voltages too good and I was using some very small 6V6 OPT's at the time and their performance wasn't so great either.
One of them eventually broke down and could not hold the bias voltage anymore.
Soon I will have my little panels up and running again.
Once I get back to square one ,I will build some thicker frames out of some .093 stock as the ones that they have now is .050 in order to check this theory again.
As I can now measure the exact voltages and have two Identical channels (except for the panels) and monitor the signal levels using my mixer.
I didn't have the mixer or amps stuff setup in 2003 yet.
jer
Although I didn't get to do a complete controlled affirmation on this but at the time I was using an SPL meter and a good ear.
This was back when I first built my larger panels and I would swap out frames of different thicknesses,But I was distracted from the coating not being able to handle the higher voltages too good and I was using some very small 6V6 OPT's at the time and their performance wasn't so great either.
One of them eventually broke down and could not hold the bias voltage anymore.
Soon I will have my little panels up and running again.
Once I get back to square one ,I will build some thicker frames out of some .093 stock as the ones that they have now is .050 in order to check this theory again.
As I can now measure the exact voltages and have two Identical channels (except for the panels) and monitor the signal levels using my mixer.
I didn't have the mixer or amps stuff setup in 2003 yet.
jer
Remember for constant charge ESLs:
SPL is proportional to ===> (Vbias x Vsignal) / (D/S)^2
So, if you double the D/S spacing and want the same SPL you will need to double the Vbias, AND double the step-up ratio to get it.
If you only double Vbias, keeping the same step-up ratio(and thus Vsignal), SPL will be -6dB.
If you keep both Vbias & step-up ratio the same, SPL will be -12dB.
Hi,
fperra, a stator stator distance of 0.12" would be more than sufficient for a mid-high panel. A DS of 0.12" is the dimension for a Fullranger.
Calculate the required excursion demand for the desired frequency range and You´ll see that the excursion demand for freqs >>100Hz becomes very small.
Increasing D/S more than required spoils much more than You could ever gain from it. It requires more drive power, reduces dynamic range, reduces bandwidth, requires more complex transformers and simply sounds less good.
jauu
Calvin
fperra, a stator stator distance of 0.12" would be more than sufficient for a mid-high panel. A DS of 0.12" is the dimension for a Fullranger.
Calculate the required excursion demand for the desired frequency range and You´ll see that the excursion demand for freqs >>100Hz becomes very small.
Increasing D/S more than required spoils much more than You could ever gain from it. It requires more drive power, reduces dynamic range, reduces bandwidth, requires more complex transformers and simply sounds less good.
jauu
Calvin
I can't think of any advantage to heat shrinking before stretching.
As far as heating after stretching, you will probably find the tension will actually be reduced not increased.
Diaphragms that use mechanical tensioning, tend to lose some of their tension over time,
slowly stabilizing at some value lower than the original mechanical tension.
According to Calvin, heating the diaphragm after mechanical tensioning will quickly bring the tension to this equilibrium point,
and little if any further drift will be seen. I have yet to give this a try myself.
http://www.diyaudio.com/forums/planars-exotics/103362-diaphragm-heat-treatment-3.html#post2457607
For woofer panels where the low end of the bandwidth is defined by the diaphragm resonance,
I would think heat shrinking to stabilize the diaphragm resonance frequency would be a good idea.
For mid/tweeter panels where diaphragm resonance is well below the crossover point,
I don't think it really matters one way or the other.
I heat treat the Mylar before stretching for just the reasons decribed by bolserst!
My theory is that I can get a more acurate tension of the film that will last longer this way. By heat treating the film I get a "harder" plastic with "built in tension" as the polymer chains are tighter from the start. (hope you understad that expenation)
I have not had time to do proper tests to verify this yet!
Roger
My theory is that I can get a more acurate tension of the film that will last longer this way. By heat treating the film I get a "harder" plastic with "built in tension" as the polymer chains are tighter from the start. (hope you understad that expenation)
I have not had time to do proper tests to verify this yet!
Roger
That`s a nice theory perhaps you can experiment both ways and find out for sure. I do not think that the heating process adds anywhere near enough energy to the film to enhance cross linking. I had a bunch of mylar film crosslinked (they told me I was the first to ever do so DuPont even contacted me after asking if I had any objections to them trying it). Point is the company who did the crosslinking for me had to just about melt the film to get it to work so I don`t believe that a bake in a warm oven is going to do what you think it will. I would simply stretch the film. If you stretch to near bursting point say 75 - 80% you wont have any room left for the film to continue stretching as your travel will use up most of that so the film ought to stay stable and not break. That`s just my take on it. Best regards Moray James.
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