The IAG company is even more cautious and rates the newer ESL 2905 at a continuous voltage of 10V, program peak level for undistorted output at 40V, and the permitted peak at 55V.
Wrt the sensitivity, I should have made clear that the 82dB-83dB was my estimate based on measurements (larger measurement uncertainty for a large panel) and subjective comparison to other loudspeakers with a sensitivity of ~86dB. So it's more a mix, sort of "perceived" sensitivity. 😉
I have to check, but could the 1.5 microbar/V figure be calculated from Walker/Baxandell's equations considering the dimensions/voltages and distribution characteristics?
Those voltage levels are exactly the same as those on page 8 of the ESL-63 manual.
Could the directivity lead to a lower perceived sensitivity? For a given on-axis sensitivity, a dipole radiates 4.77 dB less power integrated over all directions than an omnidirectional speaker, if I'm not mistaken, so the reverberance will be weaker.
Could the directivity lead to a lower perceived sensitivity? For a given on-axis sensitivity, a dipole radiates 4.77 dB less power integrated over all directions than an omnidirectional speaker, if I'm not mistaken, so the reverberance will be weaker.
I have designed a couple of DC speaker protect systems.
One used an 8 pin PIC micro and relay. Simple AC detect using voltage divider into PIC pins. DC for 500ms and relay shuts off. Also had 4 second power up delay.
The other used an 8 pin PIC micro and a discrete solid state mosfet relay.
Both worked very well.
I also designed one with mains fail detect and over current detect as well.
One used an 8 pin PIC micro and relay. Simple AC detect using voltage divider into PIC pins. DC for 500ms and relay shuts off. Also had 4 second power up delay.
The other used an 8 pin PIC micro and a discrete solid state mosfet relay.
Both worked very well.
I also designed one with mains fail detect and over current detect as well.
Luckily, all my amplifiers are transformer coupled except for the SE MOSFET amp I made which is capacitor coupled.
My "protection" relay is wired so the bias supply turns on B+ so if there's a bias failure, the main B+ power is cut instead of blowing fuses/resistors or redplating tubes.
My "protection" relay is wired so the bias supply turns on B+ so if there's a bias failure, the main B+ power is cut instead of blowing fuses/resistors or redplating tubes.
Those amplifiers would have a hard time to damage speakers with DC at all. Most want good bass, that is why DC coupled was more or less invented.
I've bottomed out my share of speakers on them... They make excellent bass but then again I don't use small cheap transformers and the PSU has capacity and less than 10R in it.
OT
Could be, but the other speakers weren't Omnis, just the usual mix over the audio band.
Maybe, I was fooling myself (the way lower distortion in the ESLs might provoke to hear at a higher level) but, besides the measured difference, the volume pot position constantly indicated a higher level.
The steel frames used for the professional version of the Quad 63s were probably cat-proofed and even improved the sound as well.
Could be, but the other speakers weren't Omnis, just the usual mix over the audio band.
Maybe, I was fooling myself (the way lower distortion in the ESLs might provoke to hear at a higher level) but, besides the measured difference, the volume pot position constantly indicated a higher level.
The steel frames used for the professional version of the Quad 63s were probably cat-proofed and even improved the sound as well.
Koda...
I wired it that way on purpose.
In case a child plays with the volume control, and you don't notice it when turning the amp on.
On power up, if it senses if DC or a loud volume level, it prevents connecting the speakers.
If volume is at a reasonable level (adjusted by the pot) then the relay closes, (after 5 second delay) and removes volume sensing, and allows normal operation even full volume.
So if you turn on the amp with no relay action going on, simply lower the volume momentarily.
And yes, this is designed for cap-coupled outputs, single-supply, and transformer/tube amps.
And for those cap-coupled amps, it eliminates the POP noise when they charge to the half/v state.
So it's latching? Because it looks like as soon as it turns on the speakers, it can't detect input voltages anymore unless I'm missing something.
This seems more complete:
This seems more complete:
In addition, should the need arise.....
The addition of another transistor can include a minus DC voltage sense issue like in bi-voltage direct coupled amps.
Although I didn't include that in this current version.
The addition of another transistor can include a minus DC voltage sense issue like in bi-voltage direct coupled amps.
Although I didn't include that in this current version.
Basically, yes.
If it senses an issue before the relay kicks in, it simply won't trigger it.
The DC voltage across the 47uF cap must be zero to allow the 100uF to charge during the delay.
Here's an open source speaker protection board on Open Source Hardware Lab.
https://oshwlab.com/cmircea2006/soft-start-and-spacker-protection
https://oshwlab.com/cmircea2006/soft-start-and-spacker-protection
Would the mentioned Amplimo relay also work well in a line level application?
Inrush would be nor more than 20 Amps. From the data sheet I´d say yes ,but I am no relay expert.
many thanks
Inrush would be nor more than 20 Amps. From the data sheet I´d say yes ,but I am no relay expert.
many thanks
No it makes no sense to do so for line level applications but what line level application should endure 20A? That is heavy muting 😉
BTW the relays are 16A rated.
BTW the relays are 16A rated.
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