Input impedance for Adcom GFA 555?


I’ve owned a pair of these amps since I bought them in the late 80s and now I’m adding a Vandersteen 2WQ subwoofer and to set the crossover I need to know the input impedance of the power amps. A couple Google searches lead me to an impass because I see both 100K ohms and 22K ohms listed. Note this is the original GFA555. Can anyone out there help me confirm the actual value? Thank you.

cantarkus

Thanks guys! Adcom is definitely still in business so that is a sound recommendation. As far as main speakers, I have Vandersteen 3A’s.

OP: Ok, sealed then!

You might also want to look at the AM Acoustics room mode simulator.  Try to keep your speakers, subs and listening location out of the way of the bottom most room modes.

Hey guys, I have a system up and running and so far I’m very pleased! Lots of tweaking left to do but I have a question right out of the shoot: I  have a grounding issue because I’m getting home from the sub. Step one in the owners manual is to ground the sub to either the main amp or preamp. Since I am I am bi-amping, I will ground it to the preamp. So…where is this the grounding connection on the 2WQ??I guess I’m being overly cautious - there is only one connection whose use is not clearly labeled so by process of elimination that must be it, but I’m just not sure. I would attach a photo but it’s not clear how to do that.

Well, egg on my face, after getting down on my hands and knees and peering underneath what I called the RCA jack is actually just a binding post and there is a grounding symbol underneath it. Mystery solved!