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ARC Ref 3 Main Output Impedance Question

I need some advice on how to hook my ARC Ref 3 pre up to my self-powered Paradigm Signature Servo subwoofer. As further explained below, ARC recommends that I use a crossover/connector tdevice hat has a higher input impedance than the one I currently use and is set up for balanced operation.

The Servo's input impedance is 25KOhms in SE mode and 20KOhms in balanced mode. I use the Servo for low frequencies (10hz to 35hz) in mono mode. To do this, I sum the L/R outputs of the Ref 3 by using a Paradigm X-30 crossover unit. The X-30 has an input impedance of 20KOhms in SE mode. There is no provision for balanced interconnect.

My Ref 3 is connected to the rest of the system as follows. Main 1 outputs are connected directly to my ARC VS-115 in balanced mode. The VS-115 has an input impedance of 300KOhms in balanced mode. Main 2 L/R channels are connected to the X-30 unit in SE mode. The X-30 sums the channels into mono and connects to the Servo is SE mode.

Based on a call with ARC, I was advised that my current subwoofer set-up is compromising the sound quality of the Ref 3 because (a) the X-30 input impedance of 20KOhm is the bare bones minimum that is recommended and (b) I am running one Main output in balanced mode and the other Main output in SE mode. Further, I was told that the current set up is making the Ref 3 work harder than it should.

ARC recommend that I use a crossover/connector device that operates in balanced mode and has a higher impedance than 20KOhm. If I recall correctly, something north of 40-50KOhm would be much better.

Any suggestions would be appreciated. Thanks
bifwynne
bifwynne OP
2,206 posts
 
Vmk & Atmasphere:

Thank you very much for the suggestions. I called Tom Tutay and discussed the problem with him. Tom will build a custom connector box having stereo SE and balanced inputs and a mono SE and balanced output. The inputs will have a 300KOhm impedance, which should match well with the ARC Ref 3 Main 2 output. As stated in the OP, the Main 1 balanced output is also loaded at 300KOhms into the VS-115 balanced input, so the Ref 3 Main 1 and Main 2 balanced outputs will see the same load.

The price was very reasonable, especially since the device will be custom built to my spec. Tom was very knowledgeable and seems like a real gentleman. I'll report back when I get the unit and try it out. Tom said that it will take a couple of weeks to build.

Thanks again for the help!
hifigeek1
770 posts
 
Bifwynne, Tom is a great guy. I have had quite a few nice conversations with him...
bifwynne OP
2,206 posts
 
Hifigeek, agreed 100%. I should get the connector device in about 7 to 10 days. Tom is loading the balanced input at 330KOhms, which is close to the input load of my ARC VS-115, which is 300KOhms balanced. Does that seem good to you?

BTW, as crazy as this may sound, Tom does not use a PC, does not advertise on the net, nor does he subscribe to A'gon or other similar forums. So, he relies entirely on hand out ads and word of mouth.

I look forward to receiving the connector so I can objectively review it. Tom comes with such high recommendations, I can only assume I will be 120% satisfied. So . . . after I get the device and review it, I would like to help Tom out by posting something a little more conspicuous than a forum thread. I'll figure something out.

BTW btw, another A'goner just raised a very similar question to the one on this OP. It goes to show you that this issue does arise from time to time.

Be well and regards.
no_money
638 posts
 
hmmm.... never looked at this. I have a REF2 connected SE to a Velodyne. Am I working the pre to hard?
bifwynne OP
2,206 posts
 
No_money, I don't know. Call Cal at ARC. He'll want to know how you hooked up the Ref 2 to your amp and sub, i.e., balanced and/or SE, and what the impedance loads of each application are.

In my case, I had a double problem: (1) the imput impedance of my pre was too low; and (2) the Ref 3 was asymetrically loaded, i.e., Main 1 to the amp was balanced and Main 2 to the sub was SE. Not a good set up. Cal explained that as a result, I was prematurely aging the tubes AND potentially denigrating sonic performance.

If Cal thinks you need a buffer device to increase the impedance loading of your Ref 2 and sum the channels into mono for the sub, call Tom Tutay at Transition Audio Design. His number is listed above. The other posters above say he is solid. He's currently building an impedance/channel summing custom buffer for me.
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