Hi Jer,
I'm curious about my speakers' impedance too, since I have no way to measure it and I don't know how to calculate it. My Carver amps drive them with no problem but I'd still like to know their impedance. Anyway, I'm using the same tranny setup as Mavric: Tandem 230v/2x6v toroids wired backwards with inputs parallel and outputs in series to give a theoretical 76:1 step-up; although I'm told the step up is somewhat less in praxis (68:1). My panels are 12x48 inches with 1/16" d/s spacing. Also, I have a 1 ohm resistor in front of the trannys, just to be safe.
okay.hears the formula,first you caculate the area 12"(l)*48"(h)*.51(percent open area)=293.76 sq. inches and (1/16"d/s*2) .0625*2=.125 then you enter these values into (search) "capcitance calculator" with dielectric constant of 1 for air you get 528.2978 pico farads, then you (search) "reactance calculator) and enter 528.297pf (or rounded if you wish) and enter highest freq. of 20khz and you get 15.063kilo ohms,your turns ratio is 230/6=38.3*2(because the secondary is in series)=76.6:1, final impedence is 15063ohms (capcitive reactance)/5867.56(turns ratio 76.6 squared)=2.567ohms+1ohm(resistor)=3.567 ohms final impedence mileage may and be lower, as i didnt acount for the stator coating ,but thats basicaly it 3.56 ohms at 20 khz which also means 35.6ohms at 2 khz, and 356 ohms at 200hz.don't be alarm by the higher impedences as at doesn't bother todays ampilfiers but as you know the lower ones are the critical ones that cause exessesive current draw ,instabilities and failure.hope that helps. jerr
hey guys, just got home @12.00 est. time. I am familiar with impiendece rise, but this is all new to me, thats why Charlie and chose an an electonic crossover and go hybrid,
I do not have the exact deminsions of the panels that we will building, but that is very usefull info.
Charlie, is providing his inovative diaghpram, when ever and as soon as possable, i will bring him that mylar type diagphram so that someone more experienced than me can check it out, i thought it might me a good substite as we throw the stuff away.
let me explain a little better, im tired and sleepy.
the mylar is the very thin film that is attatched to window tint, like a protective barrier, so you wont scratch the as you shape it for a window, which means that you can shrink and mold it with a heat gun or hair dryer, the downside is that is non porus, and I think the coating may not stick, so i will leave that to the professionals here.
I had no idea this would be what it is, me building something of this nature, like i said, i look for ready available materials and ask questions.
other wise, Charlie has what i want and anticapate a very nice ESL.
Sleepy, thanks Charlie and Jer, i will have to read that formula again when I have some rest, 12 hrs straigt is tough. and have only 5 hrs sleep for friday, another 10 hrs. thanks and take care. later
I do not have the exact deminsions of the panels that we will building, but that is very usefull info.
Charlie, is providing his inovative diaghpram, when ever and as soon as possable, i will bring him that mylar type diagphram so that someone more experienced than me can check it out, i thought it might me a good substite as we throw the stuff away.
let me explain a little better, im tired and sleepy.
the mylar is the very thin film that is attatched to window tint, like a protective barrier, so you wont scratch the as you shape it for a window, which means that you can shrink and mold it with a heat gun or hair dryer, the downside is that is non porus, and I think the coating may not stick, so i will leave that to the professionals here.
I had no idea this would be what it is, me building something of this nature, like i said, i look for ready available materials and ask questions.
other wise, Charlie has what i want and anticapate a very nice ESL.
Sleepy, thanks Charlie and Jer, i will have to read that formula again when I have some rest, 12 hrs straigt is tough. and have only 5 hrs sleep for friday, another 10 hrs. thanks and take care. later
Thanks Jer for explaining the impedance calculation!
I'm still struggling to understand how an amp reacts to such a varying load, as I would think that a typical music signal over a given short time frame would be a mix of frequencies as opposed to a constant frequency/constant load of significant duration (what's a "significant duration" to an amp?)-- anyway, pondering that and trying to understand the actual risk to the amp...
I'm still struggling to understand how an amp reacts to such a varying load, as I would think that a typical music signal over a given short time frame would be a mix of frequencies as opposed to a constant frequency/constant load of significant duration (what's a "significant duration" to an amp?)-- anyway, pondering that and trying to understand the actual risk to the amp...
see if this helps,charlie, are you familar with op amps (short for the term, operational amplifier)? a power amp is but nothing mor than a great big op amp capable of producing a larger amount of voltage and current swings than a 8 pin i.c. can, but the principle is the same.negitive feed back forces the the circuit to drive more or less current to the load regardless of the output resistance to achieve the the voltage required which is determined by input voltage times the gain of the amplifier.for instance if your your amp has a gain of 30,then with a 1v input it's suposed to produce a 30v output ,ac or dc,now if you have let say a 1000 ohm load across the output, ohms law says v/r=i so then your amp only has to provide .030 amps (or 30 milliamps) of current to produce 30v across the load.now if you were to put a 1 ohm load across it's output, due to ohms law the amp will be required to produce 30 amps of current to get 30v across the laod and acording to ohms law power =volts squared divided by resistance so 30*30/1=900 watts .your average amplifier cannot produce that much current and this is were clipping occurs and this is why amps fail when such a low impedence load is hooked to them ,and why high power amps have so many output devices per channel.that is to deliver massive amounts current when need.which the reason i'm very sceptical about car amps as i'm sure that there are some that actualy produce that kind of power but i find it very hard to believe that the cheaper ones do and do it cleanly.but thats an arguement i wish not to start,at least not here.i hope that helps you understand. jer
Thanks again, Jer. You explained that very well and I now have a better idea of the relationship between the load impedance and current draw. Since an ESL's impedance is frequency-dependent, I would assume the frequencies and amplitudes present in most music would result in some pretty wild dips and peaks in impedance and current draw. If that's so, it seems to me the questions then become how much of the music resides in the "low-impedance" region and how well amp handles (or doesn't handle) the impedance dips.
Since my Carver amps have been driving my ESL's for almost two years now and they never get more than luke warm (Carvers never get hot) and the VU meters are nowhere near pegged when playing really loud, I'm not too concerned about my amps. I'm picking your brain to get a better idea of how well Mavric's 100w/ch Adcoms will fare driving ESL's similar to mine.
I guess we won't know for sure until we wire em' up and let her rip!
Since my Carver amps have been driving my ESL's for almost two years now and they never get more than luke warm (Carvers never get hot) and the VU meters are nowhere near pegged when playing really loud, I'm not too concerned about my amps. I'm picking your brain to get a better idea of how well Mavric's 100w/ch Adcoms will fare driving ESL's similar to mine.
I guess we won't know for sure until we wire em' up and let her rip!
my amps are Adcom gfa-gfa-545 with roman # 2 beside it, rated at 100*2@ 8 ohm and 200*2 @ 4 ohm, both are the same and have instant clipping alerts per channel built into the front. I even had an old friend test the alerts with his scope, he does or did repair work, and told me there dead on when a square wave was present, so thats were my crossover somes in, i guess like Charlie had mentioned, better safe than blowing up your amp. I hope that makes sence, i have to be a liitle brief as my wife is well, what wifes do when you are the computer. Bi@#$.
i will look it up,i thought you had the gfa-555 so i was reading the manual and reviews on that one. while i was looking it up i found this, http://www.sanderssoundsystems.com/index.php?option=com_content&task=view&id=55&Itemid=134 the guru has done it again,im so jealous. i have the utmost respect that man,roger sanders.i'll always cherish the moments that i had conversations with him and how he was kind enough to help me a little pee on diy'er and give me some insights on his methods,views and technologies. thank you roger, thank you. jer
I feel the same way about Mr. Sanders; although I've not had the fortune to communicate with him personally. I got the basic idea for my beam splitter TL from his "cookbook" (radically modified, of course) but if had had seen the speakers he's building now, I might have taken a different path with mine-- I really like his compact TL configuration. Unfortunately, it looks like his new ultra-stat panels would not easily lend themselves to DIY.
i don't for see any problems using your gfa-545's for normal listening levels,but if your any thing like me my listening levels are not normal(ha ha ha).seriously though ,i don't really forsee any problems driving your panels with reference to load impedence unless you plan drive them hard,in which case of course you just get a bigger amp.all of the reviews i have read none of them were bad.i almost got a set of adcoms back in the mid to late 80's to power some infinity sm-150's, but i had a big ol maranzt 70 or 90 watt that did the job quite well. those were some rockin speakers 300 watt rms at 101db sensitivity, loud and clean, yea ,thats the way i like it!what kind of loads have you tried since you said they don't like anything less than 4 ohms?just wondering, because i once had a sansui g-9000 (biggest receiver ever made 160 wpc it was in mint condition that i got in a pawn shop for $200)that blew up when i had 3 speakers (2.6ohm load)hooked to it. needless to say it was stolen after that (ha ha ha ha ), ironicaly just last week i found the service manual online for free, now i'm p.oed all over again.becuase if i didn't or couldn't repair it i would have had it done! jer p.s he explains this in his new white paper
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I feel the same way about Mr. Sanders; although I've not had the fortune to communicate with him personally. I got the basic idea for my beam splitter TL from his "cookbook" (radically modified, of course) but if had had seen the speakers he's building now, I might have taken a different path with mine-- I really like his compact TL configuration. Unfortunately, it looks like his new ultra-stat panels would not easily lend themselves to DIY.
Jer, i have had these amps for quiet sometime. I used one to run four 8" carbon mid bass w/passive x-over for at least 10 yeras, the other was for surround on small rear speakers. 6/1/2 nothing special. these amps are very heavy, the power supply takes up most of the room. but as mentioned, i have never tried anything below 4 ohm on these amps. they are fused in i think, four different places, and unfortunatly as i have grown older, the fuse rating is probally what should NOT be there. That will be addessed as well as the build, like Charlie, i allways have a back up amp. the same of course.
there is another question Jer, are you telling me that i can run my stats without any issue? or should i be precautious and use the cross over? From what i have read, the impeidence will rise at high freqency, but not drop below low???? I guess i need some more sleep, 60hrs, and still tomorrow.
there is another question Jer, are you telling me that i can run my stats without any issue? or should i be precautious and use the cross over? From what i have read, the impeidence will rise at high freqency, but not drop below low???? I guess i need some more sleep, 60hrs, and still tomorrow.
yes, your amps will be fine the amp i used was a (don't laugh) lxi from sears (now you can laugh) that was rated at 100 wpc ,but only did like 35 wpc clean and a aiwa cd unit thats supposed to do 80 wpc, but it don't and they worked okay,loud enough to enjoy though.thats my problem i don't have any way to properly drive them right now and i only have one tube output transformer to work with right now.your amp is rated at 150wpc at 4 ohms and pretty sure 3 ohms wont hurt them as they are professional high quality amps,however 2 ohms might be pushing it, as with all amps.yes you can run without a crossover it won't hurt them but if your using a d/s of 1/16" then there is the possibility of the diagphram hitting the stator making a slapping sound like woofers do on the low notes when they bottom out.it sounds awlful but it is not going to damage the diagphram.on ocasion the mylar might stick to one of the stators in which case you turn off the bias let it discharge and then power it back up again.you will be amazed at the sound when running fullrange (no crossover),you may even prefer it.it is suggested that you use a larger d/s spacing if decide to go that route i used 3/32"on mine which coresponds the 1:100 spacing vs width (.090"/9") ratio for 12" wide panel i would consider 1/8" but i would start with 3/32".anyway i am assuming your going to use a woofer,so 1/16" spacing is best for a nice high efficiancy panel remember high efficiancy is what were after anyhow,quality comes with nature of the beast.i hope this help,let me know if you don't understand and i will do my best to explain. jer
Hi,
the low resistive impedance value at elevated frequencies is usually not the point of problem with typical amps featuring global feedback. Its rather the complex load of the panel, i.e the required additional complex current part that stresses the amplifier over due and the phase shift that eventually makes an oscillator out of the amplfier. Try the search function to find infos. That´s the reason why transformer coupled amps (tubes) and global feedback free amps typically have less problems driving ESLs.
"Unfortunately, it looks like his new ultra-stat panels would not easily lend themselves to DIY."
Actually it is probabely the easiest way, because You need not build anything Yourself. Just send Your PCB manufacturer of choice the layout-data. Every PCB-manufacturer is able to manufacture such a stator after Your fashion only limited by size constraints.
You can achieve similar results with single sided PCB material and the copper side coated with an insulative coating (see Beveridge, see Quad, see Ron Wagner´s book).
jauu
Calvin
the low resistive impedance value at elevated frequencies is usually not the point of problem with typical amps featuring global feedback. Its rather the complex load of the panel, i.e the required additional complex current part that stresses the amplifier over due and the phase shift that eventually makes an oscillator out of the amplfier. Try the search function to find infos. That´s the reason why transformer coupled amps (tubes) and global feedback free amps typically have less problems driving ESLs.
"Unfortunately, it looks like his new ultra-stat panels would not easily lend themselves to DIY."
Actually it is probabely the easiest way, because You need not build anything Yourself. Just send Your PCB manufacturer of choice the layout-data. Every PCB-manufacturer is able to manufacture such a stator after Your fashion only limited by size constraints.
You can achieve similar results with single sided PCB material and the copper side coated with an insulative coating (see Beveridge, see Quad, see Ron Wagner´s book).
jauu
Calvin
Jer, thats exactly why i purchesed a variable crossover, as you said that brand was fantastic. I guess that way, i can turn off the powered subs, attenuate the lower freqency, and see how it sounds at a lower volume of course.
I myself like loud or better said, room filling with no distortion, so if i want to play to play music, say , eating diner or just something to listen to while i do work around around the house, i can lower my cutt off and hopefully not have that slapping sound, if so, raise the cutt off higher and use the subs for the extra oohmph, am i correct on this?
on another note, next weekend, I will try and meet up with Charlie, cut the panels, smooth the edges, well, prep them up to have them sprayed.
I will post the whole process of spraying on you tube, but untill then, i need a name so everyone here will know what to look for when they search it. Do my best of posting pics of prep work as i have seen no one do a "start to finish job here"
SO, Charlie, Jer, Calvin, thank you for your support, as i get some time. i want to crunch the numbers on the amp setup as well as if my amps will handle full range. Charlie has had his for some time now, breathtaking sound, so that is my goal. like a picture is worth a thousand words, Charlie's esls have my up most attention,,Klipsh has nothing on this, BTW, did some home audio, i was the helper, but it was so crazy using seven channels, not mention getting it to sound right, the phase shift will probally be a benifit in my home set up, and difusing will work even better.
Everyone have a great weekend, anniversary tomorrow, work today, everyday, so please dont close this post, I will be gone for a little while.
thanks diy, and everyone here, this site is nice i would NOT recomend it to anyone, only people that are inclined to do something differnt, which is few or none. Take care
I myself like loud or better said, room filling with no distortion, so if i want to play to play music, say , eating diner or just something to listen to while i do work around around the house, i can lower my cutt off and hopefully not have that slapping sound, if so, raise the cutt off higher and use the subs for the extra oohmph, am i correct on this?
on another note, next weekend, I will try and meet up with Charlie, cut the panels, smooth the edges, well, prep them up to have them sprayed.
I will post the whole process of spraying on you tube, but untill then, i need a name so everyone here will know what to look for when they search it. Do my best of posting pics of prep work as i have seen no one do a "start to finish job here"
SO, Charlie, Jer, Calvin, thank you for your support, as i get some time. i want to crunch the numbers on the amp setup as well as if my amps will handle full range. Charlie has had his for some time now, breathtaking sound, so that is my goal. like a picture is worth a thousand words, Charlie's esls have my up most attention,,Klipsh has nothing on this, BTW, did some home audio, i was the helper, but it was so crazy using seven channels, not mention getting it to sound right, the phase shift will probally be a benifit in my home set up, and difusing will work even better.
Everyone have a great weekend, anniversary tomorrow, work today, everyday, so please dont close this post, I will be gone for a little while.
thanks diy, and everyone here, this site is nice i would NOT recomend it to anyone, only people that are inclined to do something differnt, which is few or none. Take care
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