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Connecting class D amp to high level input on subwoofer

I purchased 2 used Von Schweikert VR-s/1 subs. I would like to run them using the high level inputs off of my Bel Canto REF500m monblocks which are class D amps. Rel has videos on this, but they are using a speakeron cable and there is some issue with the ground and class D amps. The VR-S/1 subs have standard speaker connections for the high level input.

I talked to John Stronczer, founder of Bel Canto Designs he said the outputs have ground potential but are operating in a balanced bridge.  He suggested I contact Von Schweikert to see if that would work with the subs. Talked to someone at VS, he said probably would work, he was running a VR-S/1 off of a balanced amp with no problem, but couldn't guarantee I would do no damage to amp or sub. 

As in much of life nothing is simple. Scouring the web only muddies the water.  Any advice would be welcomed.  A long shot to think someone has my exact subs and amps, but perhaps a similar set up. Thanks.
limbonner

Showing 3 responses by musicaddict

musicaddict
382 posts
 
There is something different going on with a class D and a normal class A/AB amp. I run a W4S STI-1000 with an REL B1 sub and use the speakon connectors but you must do as Bel Canto's diagram years ago suggested and use the special cable with capacitor. You can do damage if not careful.

Bel Canto put out info on this showing the use of one 10uF 100V Bipolar film or electrolytic capacitor in the amp's + output leg to the sub's + input terminal. This was for the e.One amplifiers with balanced bridged operation.  They say NO to hooking a sub's ground (-) connection if it is actually a real ground.

With the three lead Speakon plug I wired one of those capacitors to each of the amp's positive terminals left and right. I have a ground from teh amp's chassis attached to the ground leg of the Speakon 3-wire cable.There is NO sub connection coming from either - speaker terminal on the amp, left or right. This has worked fine for years.

It was tricky at first. Good luck.


musicaddict
382 posts
 

I apologize for not checking out your VR subs first. Based on having both R and L connections with + and – legs (full speaker connections) I’d suggest looking at, or checking about using the specified capacitors between your bel canto + speaker output terminals (they’re not hard to wire or solder, or find and buy) and the two + speaker inputs on the VR subs.

If this holds, you’d attach a chassis ground from your amp to the – speaker inputs (L&R) on the sub. (Nothing from the Bel Canto’s negative – speaker outputs either channel.) Not positive but this seems the same as I use. Other help?


musicaddict
382 posts
 
Glad to hear you got the information you needed. Hope my post didn't hurt.
EJ is great. Having an STI-1000 I have talked to him on the phone a few times as well as at shows. Not surprised he could help!
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