If you are lucky, it's your high voltage power supply. But more likely is that you have a panel that has gone bad. Is there any sounds coming from the panels with the amp off but the speaker on? put your ear right up to the grille and move around to listen everywhere. Anything buy dead silence is an indicator of a bad panel.
I'm guessing panel from the age and my experience with the 2805's. But I'd love to be wrong.
Sheldon
I'm guessing panel from the age and my experience with the 2805's. But I'd love to be wrong.
Sheldon
Hi Sheldon. Just tried that, and it is dead silent. Without running a test signal, it appears to be a general lowering of sound level, rather than one particular range of frequencies. I will use a sig gen and listen next to each panel as soon as I can. Remind me, which panels run full range? Is it the two bass panels, with the centre pair only radiating the higher frequencies? Or the other way round?
I have -6dB attenuators on each channel of the preamp, and reducing the opposite channel by the full 6dB almost centres the image again.
And how do I go about checking the HT supply? And they were serviced by One Thing Audio in October 2019.
I have -6dB attenuators on each channel of the preamp, and reducing the opposite channel by the full 6dB almost centres the image again.
And how do I go about checking the HT supply? And they were serviced by One Thing Audio in October 2019.
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From the ESL-63 service manual:
"When applying Steady State input signals to the loudspeaker these should not exceed 10 V rms."
From the resonance checks section that uses 8 V rms:
"Gradually sweep up and down the frequency range. The loudspeaker response should be pure and free from rattles at all frequencies except at approximately 50 Hz where diaphragm resonance occurs."
"When applying Steady State input signals to the loudspeaker these should not exceed 10 V rms."
From the resonance checks section that uses 8 V rms:
"Gradually sweep up and down the frequency range. The loudspeaker response should be pure and free from rattles at all frequencies except at approximately 50 Hz where diaphragm resonance occurs."
I would keep the volume very low if I used the sig gen. But a sweep with REW should tell me if the FR is even, especially compared to the other speaker.
I have been looking at the 63 schematic (can't find the 2805 for now) and the 8 HF diodes appear to be GP02-30. And the bridge is a DF02M. If they are the same in the 2805 then RS have them cheaply;. I just need to work out where they fit, as I don't have a picture of the pcb. If I am lucky, that will be the solution.
I have been looking at the 63 schematic (can't find the 2805 for now) and the 8 HF diodes appear to be GP02-30. And the bridge is a DF02M. If they are the same in the 2805 then RS have them cheaply;. I just need to work out where they fit, as I don't have a picture of the pcb. If I am lucky, that will be the solution.
If they sound normal, but low, I'd put my money on the power supply. Yes, they are GP02-30's I'll be glad to walk you through it.
If you look at this picture: http://quadesl.com/photos/esl2805electronics.jpg
The HV diodes are nestled in amongst the blue disk caps. At the bottom right of the PCB.
As was mentioned earlier, you should look at the neon bulb (by the curly power wire in my pic). If it looks like it's on solid, or blinking rapidly, that indicates that you have a panel problem that is pulling the power supply down. This is typically accompanied by some sort of sound from the panels (squealing, hissing, etc). If you have a problem with the power supply the neon bulb will not blink or blink at a much slower rate than the other speaker.
The power supply in that speaker is essantially the same as the newest 63's and everything after it.
Here's a good schematic to use. Keep in mind that there is a 1.5uF cap missing that normally lives across the input transformer primaries. but that's not the part of the schematic that you care about at the moment.
Sheldon
If you look at this picture: http://quadesl.com/photos/esl2805electronics.jpg
The HV diodes are nestled in amongst the blue disk caps. At the bottom right of the PCB.
As was mentioned earlier, you should look at the neon bulb (by the curly power wire in my pic). If it looks like it's on solid, or blinking rapidly, that indicates that you have a panel problem that is pulling the power supply down. This is typically accompanied by some sort of sound from the panels (squealing, hissing, etc). If you have a problem with the power supply the neon bulb will not blink or blink at a much slower rate than the other speaker.
The power supply in that speaker is essantially the same as the newest 63's and everything after it.
Here's a good schematic to use. Keep in mind that there is a 1.5uF cap missing that normally lives across the input transformer primaries. but that's not the part of the schematic that you care about at the moment.
Sheldon
I've just run an impedance sweep on the DATS V3.
Does that look reasonable? They are closer than my Tannoy MG12s!
I also ran a sig gen sweep, and after tilting the balance about 9dB, the sound seemed fairly central across the audio band, with no farts or rattles. And now playing a CD (with +9dB to the low speaker) the image again sits pretty central.*
I'm hoping that's consistent with a low HT supply.
* Using a £5 Philips DVD player from a charity shop, and a Tangent AMP50 which cost me 50p! Who needs more?
Does that look reasonable? They are closer than my Tannoy MG12s!
I also ran a sig gen sweep, and after tilting the balance about 9dB, the sound seemed fairly central across the audio band, with no farts or rattles. And now playing a CD (with +9dB to the low speaker) the image again sits pretty central.*
I'm hoping that's consistent with a low HT supply.
* Using a £5 Philips DVD player from a charity shop, and a Tangent AMP50 which cost me 50p! Who needs more?
"The peak in the bass is related to the diaphragm's fundamental "drumskin" resonance; unusually, the height of this peak will depend on the drive level; the impedance in this region increases with increasing level."
The Stereophile's interpretation is false: the 50 Hz peak is simple L-C resonance, not "drumskin"-like effect. The 50 Hz is coincidence. The drive level dependence is caused by transformer core.
The Stereophile's interpretation is false: the 50 Hz peak is simple L-C resonance, not "drumskin"-like effect. The 50 Hz is coincidence. The drive level dependence is caused by transformer core.
As the service manual
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wout31; do you have access to the full service manual? I have looked for one and couldn't find it. But then, I am pretty useless with computers.
I have just run a sweep with REW, starting at 50Hz (it didn't like 10Hz!).
I roughly levelled the two channels by ear first, and smoothed them a bit.
Interestingly, the levels above about 800Hz are similar, but below that the low speaker has more lower frequencies. Or rather less higher frequencies. I didn't bother moving the speakers, just the mic, so the room has interacted differently with each one, but I didn't think that would matter too much. This was just to test for gross variations.
Blue trace is the low output speaker. So what does this indicate? Is it just an effect of low HT, or something else
EDIT; I applied around 9dB of balance correction on the amp.
I have just run a sweep with REW, starting at 50Hz (it didn't like 10Hz!).
I roughly levelled the two channels by ear first, and smoothed them a bit.
Interestingly, the levels above about 800Hz are similar, but below that the low speaker has more lower frequencies. Or rather less higher frequencies. I didn't bother moving the speakers, just the mic, so the room has interacted differently with each one, but I didn't think that would matter too much. This was just to test for gross variations.
Blue trace is the low output speaker. So what does this indicate? Is it just an effect of low HT, or something else
EDIT; I applied around 9dB of balance correction on the amp.
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You can find it on Sheldon's homepage.
SDS Audio Labs - Modern Quad Electrostatic Loudspeaker Info
Scroll down a bit and you will find links.
Mogens
SDS Audio Labs - Modern Quad Electrostatic Loudspeaker Info
Scroll down a bit and you will find links.
Mogens
I always remove the support bar first, but you can leave the side panels and the grilles in place. I'm almost always headed for panel repairs so it's pretty rare that I need to get to the electronics only.
Sheldon
I've taken the cover off. And replaced it, plus wrapping the panels to protect them from the blasted kitten. Everything is for playing with in his world!
Before I remove the pcb to replace the diodes, what do I do about the wax(?) coating on it. Does it just melt off when I desolder? Does it need replacing afterwards, and with what?
Before I remove the pcb to replace the diodes, what do I do about the wax(?) coating on it. Does it just melt off when I desolder? Does it need replacing afterwards, and with what?