Hello all.

My 7500 showed up last week, and I'd like to report that it is truly an amazing amp. (Preaching to the choir, I know.) I'm pushing Polk lsi 15's (4 ohm), which are really hard to drive. I upgraded from a Rotel RB-985, which was great, but not quite up to the task. Now, I have more punch and headroom, not to mention clarity and subtlety. And the bass! Wow.

Anyway, I'm having some hum problems, and I'm close to tracking them all down. I ordered a Jensen VRD-1FF Cable ground isolator. I think the cable is 80% of the problem. Unplugging the cable stops MOST of the noise, but there's still a little more to track down.

Here's my question... I had a friend recommend installing an isolated circuit in the room. Has anyone tried doing that? It seems to me that if I can isolate the ground problems from the cable, everything else in that room will then be on the same single ground. Make sense? Or wasted effort?

The 7500 is very sensitive to standing DC on your AC line.
Does the hum come and go with a definite pattern?
I had problems with mine doing this and I finaly purchased a Channel Islands XDC2 AC filter and all of the problems went away immediately.

Hey Monty. Congratulations. And, keep preaching to the choir. Welcome to the club.

I had a short-lived hum issues as well. The hum disappeared after I ran all my components and incoming cable through my Monster PowerCenter.

Hi there, Monty -

I'm a happy new 7500 owner, too. Just like you, I'm driving Polk LSi15s in front, LSif/x in the rear, and a DSW pro 400 sub. Yesterday was the first time I have actually pushed the system to any degree what so ever, and what I heard brought a smile to my face that still hasn't gone away. So far, it's everything I hoped it would be, and I know I still have some tweaking to do.

Good luck to you.

What a friendly bunch here...

Candyman, what model Monster PowerCenter do you have, or what would you recommend?

Chessie, killer system. It's amazing how some good power will really make those Polks sing.

butchgo, I've run across your posts about your XDC2 from various searches. How in the world would I test to see if there's standing DC on the line? I'm assuming that all of my hum is coming from ground loops, which I'm slowly isolating. Can you check for DC on the line with just a multimeter?

Thanks everyone for all the replies.

I would get one of these. They are a GREAT deal right now...

http://store.audioholics.com/product/717/66232/apc-av-h15-1-5kva-h-type-power-conditioner---silver

Awesome, thanks praedet.

Just ordered one.

Take a look at Audioholics special on the APC H-15 for $149. Great little machine and a real good value right now.

Monty, I purchased up a Monster HTS 3500, primarily for surge protection, on close-out a couple years back. I can't say that it did anything to improve the sound, outside the hum isolation. It worth about the $149 or so I paid for it.

The APC H-15 unit that praedet and XenonMan mention looks like a bit of a step up from the Monster HTS 3500. I'd likely order it if I was in the market again.

Rob

I am too a happy new owner of an Outlaw amp. The 7700 arrived two weeks ago and its been a nice improvement to my system. I am still using my Rotel RSX-972 receiver as the pre/pro until the 997 comes out. The 7700 drives my Scan-Speak Ultimate Revelation Kit speakers for the fronts and Totem Mite-T s for the center and the rears (sides are coming). For power, I installed a dedicated line from my breaker to a Belkin PF60 in which I attach all my AV equip except for my LCD display. I receive very little hum speakers and no hum from the amp itself. Only when there is no sound playing I can here alittle bit of hum from the speakers. It is very faint and you have to put your ear to the speakers to notice it but it is there and where the Rotel had non before. However, the 7700 brings fuller sound at higher volumes and fills my HT with a sound that puts a smile on my face.