Wow. Now this will surprise a few....I have Sanders 10C speakers (nice, like, really nice). They are Hybrid ESLs crossed over at 172hz, and woofer on everything under 172hz. The single 10" (Transmission line) woofers are powered by an Icepower 1000ASP, and the panels are run off my Krell KSA-50 Clone (+/-34vdc rails).
I ran both test tones at 220hz (to test ESL panel), and 120hz (to test the woofer).
Set the volume at a nice loud setting off a Jack Johnson song (Posters on Brushfire Fairytales CD). I then played the test tones. This is what I got off the speaker terminals
220hz - Woofer - .5 VAC ESL - 26 VAC
120hz - Woofer - 6.2 VAC ESL - 2.2 VAC
After shaking my head in disbelief, I tested again, and got same numbers. This gives Peak Voltage of 104 V, and 73 VRMS on the panels. The woofers seem normal....
In conversing with Roger (just earlier today) about a suitable amp for the ESL panels, he indicated an amp that would do 60V RMS would be the MINIMUM he recommends on the ESL panels, as the impedance drops dramatically as you get closer to 20khz. With my quick calc, that's around 900 wpc @ 4 ohms... I thought that was crazy, until I did this test...
I have attached the link to Roger's White paper from Sanders Sound Systems:
Sanders Sound Systems ESL Amp Whitepaper written by Roger Sanders.
Just bought one of his ESL amps that are designed for tough ESLs like his. Around 78v rails and 56V RMS, and they should do a much better job than my Krell Clone, which is likely clipping badly at this voltage....
I ran both test tones at 220hz (to test ESL panel), and 120hz (to test the woofer).
Set the volume at a nice loud setting off a Jack Johnson song (Posters on Brushfire Fairytales CD). I then played the test tones. This is what I got off the speaker terminals
220hz - Woofer - .5 VAC ESL - 26 VAC
120hz - Woofer - 6.2 VAC ESL - 2.2 VAC
After shaking my head in disbelief, I tested again, and got same numbers. This gives Peak Voltage of 104 V, and 73 VRMS on the panels. The woofers seem normal....
In conversing with Roger (just earlier today) about a suitable amp for the ESL panels, he indicated an amp that would do 60V RMS would be the MINIMUM he recommends on the ESL panels, as the impedance drops dramatically as you get closer to 20khz. With my quick calc, that's around 900 wpc @ 4 ohms... I thought that was crazy, until I did this test...
I have attached the link to Roger's White paper from Sanders Sound Systems:
Sanders Sound Systems ESL Amp Whitepaper written by Roger Sanders.
Just bought one of his ESL amps that are designed for tough ESLs like his. Around 78v rails and 56V RMS, and they should do a much better job than my Krell Clone, which is likely clipping badly at this voltage....
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Thanks for posting your numbers, John.
The 26V is out of the amp, right? Not stepped up thru a transformer for the panel?
Just beware that Brushfire Fairytales is mastered a little hot, the RMS level of Posters is about -14dB. So on that song your average voltage would be about 2dB lower than your 26V measured. Peaks will still hit 105V or more - that's the important thing. A more dynamic CD might need more.
You need an amp that can supply an RMS voltage of at least 73V (hopefully more) into the ESL panels. To me that means an amp rated at about 650 WPC into 8 ohms, and capable of driving the low impedance load. Yeah, that's a lot of amp!
You might try to borrow or rent a pro amp just to hear how the extra headroom plays on the panels. Will they actually handle that much power?
The 26V is out of the amp, right? Not stepped up thru a transformer for the panel?
Just beware that Brushfire Fairytales is mastered a little hot, the RMS level of Posters is about -14dB. So on that song your average voltage would be about 2dB lower than your 26V measured. Peaks will still hit 105V or more - that's the important thing. A more dynamic CD might need more.
You need an amp that can supply an RMS voltage of at least 73V (hopefully more) into the ESL panels. To me that means an amp rated at about 650 WPC into 8 ohms, and capable of driving the low impedance load. Yeah, that's a lot of amp!
You might try to borrow or rent a pro amp just to hear how the extra headroom plays on the panels. Will they actually handle that much power?
I thought your voltages were not super high, but you need a lot of current for your 1 ohm speakers. Do I recall correctly?Lol, thought Mine was bad huh .....
Yes, it was at the amp. not the step up.
Roger does not recommend Class D on his panels, otherwise I could just put the ICEpowers on the panels and put something else on the woofers, as they clearly don't need that much power...I may try it anyway...if I remember correctly, my Acoustat Model 3 did give the ICEpower 1000ASP a bit of a hard time as it went into protection on a few tests. The Krell had no issues on the Acoustat...
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I had the ICEPower 1000ASP for a while, as well as some of the smaller modules. I quite liked them. The 1000 is very strong! Not sure how it or the panels would handle the RF carrier of Class-D. FWIW, the ICEPower amps had about the cleanest output in the RF spectrum of any Class-D I've looked at.
I have Posters by Jack Johnson, and verified with Logic Pro that RMS level is -10dB.
As a sanity check, I played that track, set the reference levels, and measured about 3V.
When playing that track, your Sanders 10C's panels register over 26V (676W RMS into 8 ohms).
The claimed sensitivity is 94dB. Probably not rated at 2.83V
As a sanity check, I played that track, set the reference levels, and measured about 3V.
When playing that track, your Sanders 10C's panels register over 26V (676W RMS into 8 ohms).
The claimed sensitivity is 94dB. Probably not rated at 2.83V
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Interesting. Every piece of software I try reports different RMS levels on music. Sine wave, they report the same (one would hope!). My software tells me Posters has an average level of -15.2dB on the left track, -13.8 on the right. Nice to have the Pro Tools report.
I must clarify a few things. I rarely have my amp turned up this loud, but it happens now and then. I don't NEED to play this loud in the same way I don't NEED 200 HP engine in my car, but every now and then it's fun. Also, I am fully aware that sound levels this high is HIGHLY damaging to your hearing.
I will do some more measuring when I get back from work tonight.
I am convinced that people who says that 2V is "arena/stadium level loud" have never been to a concert.
I also think this was a great idea. It gives a little perspective and shows that for most applications low watt amps work just fine. You seldom need that 1kW mono block.
Ok, here is my honest update. I played one of my favorite songs on a level I would describe as fairly loud but in no way uncomfortable. I switched CD to my test CD without moving the volume control and ran the -10dB 200Hz test tone again. The multimeter read 15V. So there you have it... I may have been a bit too loud on the first run, but 15V at -10dB would probably still set me in the 10-20V camp.
Years ago used a Yamaha P2200 to drive high impedance headphones.
The amp had nice big peak reading VU meters, calibrated with a watt reading for 8 ohms.
We were quite surprised to see full scale "350 watt" peak readings at loud (milliwatt) headphone levels.
Amps designed for a nominal 2-8 ohm loads often don't cut it driving a high impedance load.
Haha planars of course, Acoustat, SoundLab?
Don´t be fooled if you have a speaker like that.
My room is 10 x 4 x 2.6 metres and I´ll get by with 25 Volts for a pretty decent SPL at full distance not the 1 meter standard rating.
It´s the large radiating area that does the trick and the SPL seems the increase with greater distance (within reason of course).
So even with the amps I´m running at this moment which can only put out 17 Volts max (also in 1 Ohm) the SPL is still adequate enough in my room.
on the 200mv setting on my DMM playing Shirley Bassey 'Light My Fire' at volumes I reserve for 1 track only thrashes, I peaked at 21.4 millivolts
Amps is Nelsons ACA and speakers are P10's Emkens (Eminence 12 LTA 97dB/w/m with a Fostex FT17H super tweet at 8k)
So I guess thats 21.4 millivolts??? That aint much at all.......vol on a clock face starts at 6 and I got to 10 for this test
Even allowing for small English rooms and efficient speakers I must have screwed up
Amps is Nelsons ACA and speakers are P10's Emkens (Eminence 12 LTA 97dB/w/m with a Fostex FT17H super tweet at 8k)
So I guess thats 21.4 millivolts??? That aint much at all.......vol on a clock face starts at 6 and I got to 10 for this test
Even allowing for small English rooms and efficient speakers I must have screwed up
on the 200mv setting on my DMM playing Shirley Bassey 'Light My Fire' at volumes I reserve for 1 track only thrashes, I peaked at 21.4 millivolts
Amps is Nelsons ACA and speakers are P10's Emkens (Eminence 12 LTA 97dB/w/m with a Fostex FT17H super tweet at 8k)
So I guess thats 21.4 millivolts??? That aint much at all.......vol on a clock face starts at 6 and I got to 10 for this test
Even allowing for small English rooms and efficient speakers I must have screwed up
you have to measure the test signal, not the music. read again the instructions.