Polk Legend l800 amp
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Polkrt3000
Posts: 52
I have two sets of speakers in my living room one set is the Polk l800 and the other is the Goldenear one.r triton. The Polks didn’t like the normal connection to the Adcom 5802 and created a I screeching sound so I immediately turn off amp and disconnected the amp and put the Adcom 55ll onto it and put the Adcom 5802 back on the GE, seems to work fine. However I wanted to use the more power for the Polks but it must have issues with ground or SDA connections. I read somewhere you can run a wire to the two negative terminals and it will work, not sure if I want to risk it again as I feel I could have blown something. If it would work maybe I would try this but can’t seem to get a definitive answer online. Maybe I should just leave it as maybe it’s enough power for them. If it worked I would consider switching I do feel the extra wattage cleared up the GE it didn’t sound bad just better and a little louder. I know I could go with a Parasound amp but out of my price range at the moment. I had Adcom for the past 30 years and seem to like them. I use a sunfire preamp. I could maybe swing for another 5802 if I find a decent deal. Just wondering First if it is possible to use the 5802 or going to like a 585 older one not sure if that is enough of a change. 200-250 watts 8 ohms can’t remember what the 4 ohm would be for the polks.
Comments
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Sorry Adcom 555ll to be clear is being used for the polks currently
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Normally when an amplifier that is not a common ground design is connected to the L800 the only problem is that the SDA signal is reduced, not that a squealing sound is produced. This is because the L800 uses an AC coupled SDA connection as opposed to a DC coupled connection as the older SDA speaker had. The squealing isn't a symptom of a DC short, it is a reactive high-frequency stability failure triggered because the GFA-5802's high-bandwidth HEXFET design cannot handle the cross-channel AC interaction introduced by the SDA cable. Inside the GFA-5802, the negative speaker terminals are not tied directly to a shared chassis ground, instead, each channel references its own power supply ground through low-value isolation resistors.
When the AC-coupled SDA array allows alternating current to cross over, it creates an alternate path for the signal to find ground through the opposite channel's circuit. This fluctuates the reference voltage of the input stages. Because the GFA-5802's front-end is a highly sensitive, single-ended Class A circuit, any sudden fluctuation or "bouncing" of the local ground references instantly manifests as high-gain signal feedback, resulting in that squeal.
It is the unique design of the Adcom that doesn't work with the L800 unlike the majority of other amps.
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So even if I put the negatives tied together with a wire on the amp it will be an issue then as what you are saying.
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Yes, they are not compatible.
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Ok thanks
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Would a 5500 or 5800 or 585 work or would it not matter that much vs 555ll
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In looking at the GFA5500 the schematic shows the negative speaker terminal connected to ground, so it would work. Here is the schematic:
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The GFA5800 looks good also, here is the schematic:
It's upside down, but you can see the negative speaker output is connected to ground. -
It's hard to tell with the GFA585, the schematic is pretty confusing, sorry.
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Would I notice much difference, in switching amps for bass and treble and mids
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With the 5500 or 5800
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It’s good to know the 5500 and 5800 would work just not the 5802, not sure on 585 it’s about the same watts as 5800 like 250 8 ohms
