Yes yours.
You said: "Sure enough at the 1st bass drum hits, right speaker shuts off and the voltage meter on my Pass xa 30.5 swings wildly to the right. "
Sounds exactly like the protection circuit kicked in. There are two protection circuits on the 2805's, the main one is a set of three diode bridges with zeners across them that forms an AC clamp circuit set for about 7KV peak to peak. When that one is active, it sounds like an amplifier mildly clipping. What you are describing is the sound of the Triac based antenna sensing clamp circuit which is triggered when a panel arc's. When that circuit triggers, the input is clamped for a second or so, and possibly longer if the polyfuse has to cool back down.
The power meter swung wildly to the right because the amp was sourcing power into a nearly dead short. The amp can handle the normal load of the quads just fine, but it rightly struggles when the clamp circuit is engaged.
I can't speak to your room damping issues, other than to say less is more with the quads.
Sheldon
quadesl.com
It's a protection circuit, designed to prevent permanent damage. If they're still playing, you should have many years of service to enjoy.
Sheldon has years of practical experience, so consider his advice.
http://quad.hifihaven.com/model/ESL-63/article:Quad-ESL-63-trouble-shooting
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Sheldon has years of practical experience, so consider his advice.
http://quad.hifihaven.com/model/ESL-63/article:Quad-ESL-63-trouble-shooting
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Thank you. I really appreciate everyone's comments here. I researched arcing online. I sat in the dark last night and listened at normal levels, even a little higher sometimes, around 87db to 90 for short times. No blue or any kind of flashing lights. No clipping and bass seems fine. I may have dodged this one bullet, I hope. Assuming that I haven't destroyed the so called clamp. Funny thing is that the living room upstairs is natural wood floors and not carpeted like the man cave.... Ummmm
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The 63's and newer are a whole lot more forgiving of arcing than the 57's.
The 57's have a lot of design "uniqueness" that Quad abandoned ASAP. One of the side effects of the 57 treble panel design is that the conductive portion of the stators is on the inside and about 25 thousandths of an inch away from the diaphragm. So if there is an arc, there is a very good chance that any carbon buildup from that arc will short the diaphragm to one (or both) of the stators. That effectively shorts out and ruins the panel.
The 63's and newer are a much more robust design. An arc will burn a hole in the diaphragm but that is about all. Given how much diaphragm area you lost, you'll never know it or be able to measure it.
The antenna based clamp circuit is designed not to prevent an arc, but to shut the speaker down after the start of the arc to prevent the arc from setting the diaphragm on fire and eventually your apartment.
As a note, you can also damage the protection circuits if they are hit extra hard, the symptoms are vastly reduced sound level in the speaker. Don't worry about the arc, but try to keep the volume below where either protection circuit kicks in. The quads are a scalpel, not a chainsaw.
Hope that helps,
Sheldon
quadesl.com
The 57's have a lot of design "uniqueness" that Quad abandoned ASAP. One of the side effects of the 57 treble panel design is that the conductive portion of the stators is on the inside and about 25 thousandths of an inch away from the diaphragm. So if there is an arc, there is a very good chance that any carbon buildup from that arc will short the diaphragm to one (or both) of the stators. That effectively shorts out and ruins the panel.
The 63's and newer are a much more robust design. An arc will burn a hole in the diaphragm but that is about all. Given how much diaphragm area you lost, you'll never know it or be able to measure it.
The antenna based clamp circuit is designed not to prevent an arc, but to shut the speaker down after the start of the arc to prevent the arc from setting the diaphragm on fire and eventually your apartment.
As a note, you can also damage the protection circuits if they are hit extra hard, the symptoms are vastly reduced sound level in the speaker. Don't worry about the arc, but try to keep the volume below where either protection circuit kicks in. The quads are a scalpel, not a chainsaw.
Hope that helps,
Sheldon
quadesl.com
Well, today I sat down for a few minutes for a test, I now notice that the bias meter on the pass 30.5 is a couple of notches to the right side of dead center. It used to always rest a couple of notches to the LEFT of 12 o'clock. I wonder if the speakers are loading or what have you. I have a show tonight, but I will look into it tomorrow. Sound is good but I am getting random artifacts and some protection intervention at around 87 to a 90 db, not reliably or consistently. I want to try my rogue class D amp tomorrow to see what happens. I am also getting the subwoofer tomorrow. Busy day!
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That sounds like a panel problem. With the speakers powered up, but the amplifier off (or disconnected), do you hear anything when you put your ear up to the speaker? Put your ear up next to each panel and listen.
That's too low for the protection circuit to be kicking in. That's just a couple of watts. I'm assuming that when you say "protection intervention", you mean the one that mutes the speaker for a second or so?
Sheldon
quadesl.com
I didn't like the sound using the internal crossover, so I went with playing the speakers full range and 43hz support from sw, controlling the volume. A little rudimentary but managed to get a nice balance on music that I know well and have played for years on many other systems. The bias meter on the amp was back to 11 o'clock and I manage to listen to stuff with heavy bass content at 87 to 93db levels without incident. I'm happy with that for now. Sounds loud enough and the sw fills enough that there's no need to raise the volume so much. Haydn symphonies, Bach cantatas and solo piano sound natural and unaffected. Organ music, pink Floyd and electronica, on the other hand, are impressive. I definitely have to work on the resonances around 32hz and others. The sw offers eq per frequency. I need to stop obsessing about this hobby.
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Hi all, a big thanks for your help and expertise. I wanted to give you a final report on my case with the 2805s and the Pass 30.5. My conclusion is that the Pass is basically clipping during complex orchestral passages, I guess, something to be expected from a 30w amp trying to drive the crazy ESL impedance Rollercoaster. I know this because switching to the old Rogue Pharaoh, there isn't a hint of danger, shrillness or instability. This hybrid behemoth actually plays them to the point that they get too loud. Now, the very few instances of the speakers protection circuit intervening are manifested by a gentle reduction in volume and no drama. The bass is strong and I find myself not using the subwoofer at all. I am now convinced that the speakers were never really damaged, it was the amp clipping and triggering the protection. I also replaced the 12ax7 in the rogues preamp section for nos German telefunkens. Curiously, it has a lot more gain. Of course, the rogue doesn't have the sophistication of the Pass, but at this juncture, there is a lot to be said for functionality. I can attest that in terms of simbiosis, the rogue pharaoh and my Quads are a marriage made in heaven. The only potential issue is that this is a very powerful amp (180wpc) and so accidents have to be avoided at all cost. I will continue to enjoy the music and forget about the gear for now. Hope it lasts!
Hi pedrobe.
Nice to hear that it sounds good.
I see on your picture that the speakers are very close to the back wall (3-4 feet)
My advice to everyone using full range dipole speakers is to have at least 3 meters (10 feet) air behind the speakers.
Another rule of thumb is to place the speakers 2/3 of the room length. This prevents standing waves in the low frequency region.
My room is 10 meter long 33 feet.
I have 6,7 meters behind the speakers and I'm sitting 2,6 meters from the speakers and 0,7 meter behind me to the wall.
First reflection from the sidewalls roof and floor is damped/diffused.
Anyway..
More air behind the speakers makes the sing!
Nice to hear that it sounds good.
I see on your picture that the speakers are very close to the back wall (3-4 feet)
My advice to everyone using full range dipole speakers is to have at least 3 meters (10 feet) air behind the speakers.
Another rule of thumb is to place the speakers 2/3 of the room length. This prevents standing waves in the low frequency region.
My room is 10 meter long 33 feet.
I have 6,7 meters behind the speakers and I'm sitting 2,6 meters from the speakers and 0,7 meter behind me to the wall.
First reflection from the sidewalls roof and floor is damped/diffused.
Anyway..
More air behind the speakers makes the sing!
I used this, and ended up with a 'toe-in' position with the panels angled toward my chair.
http://www.cardas.com/room_setup_calculators.php
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http://www.cardas.com/room_setup_calculators.php
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I was told that with my Quads, the impedance can go quite high during high demand low frequency episodes. In that case, my 30 watt amp would be helpless. Low impedance is not a problem for a massive class A amplifier like any Pass Labs.There inpefance is rather amp frendly to be honest , I think it won't even dip under 3,5?ohms . A decent amp should not have a problem but 30 watts is on the very low side of things
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