Low buzzing through speaks

Once I got the Sim back and connected it, buzz/hiss gone.

Looking at the rear panel of the Marantz AV8802A, I can’t help but notice that the iec power outlet is only 2 prongs; meaning the unit is technically not seeing an earth ground, until maybe a piece of equipment is plugged into it, *giving it* an earth ground. Really, trying to hook up equipment in the home audio world can be confusing sometimes, because you really have to take into consideration what is grounded, and what isn’t, and these manufacturers don’t make it easy. Not to be condescending, but it sometimes takes some knowledge trying to figure out grounds, and ground loops.

I mix both balanced and unbalanced analog equipment in my home system(s), and you have to know when the time is right to ground, lift shields, or transformer isolate. I admit, it took me years to learn all about this stuff.

I used to live on a very busy street in the days of kids cruising the highway with CB radio’s (man am I dating myself). Believe it or not, they were still heavily using CB’s in the early to mid 90’s (so maybe we’re not going back that far 😉). I was even then routing audio through my townhouse (at the time) using balanced audio, but even still, when they would drive past, their CB signal would many times blare through my system. Well, even at that point in time, I still hadn’t learned all I needed to know about balanced analog audio. So it too took me time to learn about shielding, and grounds, etc. etc. My former neighbor across the alley from me lived across the street from a ham operator, and she used to get so frustrated because his broadcasts many times blared through her TV speaker(s). Now that type of interference is tough to get rid of. Working at the radio stations, I used to get a lot of complaints from neighbors when our signals also permeated their home electronics. Not always easy trying to solve those problems.

It’s very possible attenuators might be needed in kingbr’s case. I’ve used them in broadcast studios, but I think it’s unfair to make homeowners research the need for them in a home audio system environment. One thing that bothers me about the Sim amp is that it doesn’t have any gain controls, so to put it one way, it’s wide open. IMO, that means that any little bit of noise on the interconnects will be magnified more than it needs to be (screwing up your S/N ratio). That’s one of the main reasons why I will never purchase a power amp without gain controls on it. It’s very possible that is what’s taking place here, but again, I think it’s unfair to put a home audio system owner through this frustration when purchasing expensive audio gear.

I thought maybe somehow going from the 2 prong Marantz to the 3 prong Mac may have had something to do with it. I had no idea how or why that would have an affect but it was something I thought could be playing a role…

I thought maybe somehow going from the 2 prong Marantz to the 3 prong Mac may have had something to do with it.

Yes, it’s possible that eliminated the possibility of a ground loop. My continued thought here is this is all ground related, but I’m also concerned about 29 dB of wide open uncontrolled gain on the Sim. Correct me if I’m wrong @kingbr there’s no remote control with the Sim, correct? And there’s no volume control of any sort on it, yes?

Hi @dpop!

No, no volume, no remote with the Sim...

OK thank you kingbr for confirming.

I know that some of these cable manufacturers charge an arm and a leg for some of their cables (which I will never pay for), but the construction of each, between manufacturers, is not always the same. Where one might put more emphasis on their shields, another may put more emphasis on the conductors carrying the signal (in balanced mode). Unless the cable manufacturer posts pictures of inner cable construction, you really never know what you’re getting until you try them, and how they will perform in your environment. Having already dealt with so much interference in the past (CB’ers, radio station RF, neighborhood ham operators, etc), I know that a well made shielded cable (like a Gotham), and a low impedance star ground system is always what’s needed in my audio systems, and audio systems that I build for others. For me, shielding takes top priority. Next on my list is (low) capacitance. I’ve already found that when I upgrade to a lower capacitance cable, I can almost immediately hear the improvement. I am also fortunate and thankful that I can make my own cables.