Low buzzing through speaks

Just wondering...am I correct in understanding that when all XLR’s are unplugged between the Sim and Mac, there is no buzzing? If that is the case, if you reconnect just 1 of the 5 XLR cables, does the buzzing return? If so, in all speakers?

Just for the heck of it, I would also trying connecting the grounds on the rear, between the the Sim and Mac (with any piece of wire you have laying around), and see if that changes anything. Try this with and without the XLR's connected. 

I see that both the Sim and Mac have 3 prong AC plugs. I don't think anyone has suggested it yet, but another suggestion is to temporarily (just for test purposes) lift a ground on one of the units (either the Sim or Mac), with the XLR connectors connected, and listen for the buzz. You can accomplish this by using a 3 prong to 2 prong AC adapter (hopefully you have one laying around, otherwise Home Depot or any hardware store has them). For this test, the only two units connected (with any inputs or outputs connected) should be the Sim and Mac, and nothing else. 

@kingbr

How would I connect a wire between the grounds on the amp and Mac? I don’t really see anywhere on either to connect a wire?

Looking at the on-line manuals, there’s a GND screw/connection on the back of each of the units. Connect a wire to each (from one to the other).

So just like a normal speaker wire between the 2?

Correct, but I'm still very interested in hearing the results of the other tests I mentioned.

Whilst I didn’t try the cheater plug specially, the fact that the Hum-X didn’t work leads me to believe the cheater wouldn’t have any effect. 

Sorry, I can't agree with that @kingbr  - two different concepts. If it were me, I'd still try the cheater plug. You really have to eliminate all options here. I think they're only like $3.  

@kingbr

One thing my amp is a C19 20 amp connection, I’m thinking trying the cheater on that would not be a good idea?

I did notice that in the manual diagram (that it had a 20 amp IEC connector on the rear), but it didn’t sink in. Thanks for pointing that out. Is the wall plug also a 20 amp plug (with one of the flat blades turned 90 degrees)? I’m just trying to eliminate either the Mac or Sim from an earth connection, so yes, applying it to the Mac should accomplish this.

@kingbr

So I just tried the cheater on the Mac and buzz still there

OK, good to know. Still waiting to hear if 1) buzz is in all speakers with just one XLR cable connected 2) any difference when ground wire is connected between GND terminals on Mac & Sim, with and without XLR cables connected.

Ok, so you're saying that the buzz *did* take place when the first XLR cable was connected, but you just didn't hear because it was a rear speaker, yes?

@kingbr

I disconnected the first 4 XLR’s from the Mac leaving just 1 XLR between Mac and amp connected and buzz is gone???

Very interesting. OK, let’s stay on this path for a moment. From my understanding, and just so I’m 100% sure here, you’re saying with one XLR cable connected, there’s no buzz in any of the speakers, yes? If that’s the case, I would also try using that exact same cable, and plug it into all of the inputs and outputs you use when connecting the Mac to the Sim. When doing this, does this produce the same result(s) - no buzz? I would also recommend trying that same scenario with each cable, one at a time (I know this is probably a lot of work, but what we’re doing is seeing if all cables produce the same result). It might not be a bad idea to help identify which cables are which. Maybe a sticky-note (or something like it) could temporarily be affixed to each cable for identification purposes.

I’m also wondering if as each XLR cable is reconnected (when using all of them), does the buzz increase a little bit more in volume level as each cable is plugged in (or when the buzz is heard, it always remains at one volume level)? Also, is it safe to say that when the buzz is heard again, as each cable is plugged in, the buzz is directly attributed to the corresponding channel and speaker only?

Sorry for all of the questions, but this is the only way I can diagnose this, without physically being there.

The cables are all less than 2 years old and they are Transparent Plus so they’re not cheaply made, they’re solid…

I get it. I hear what you're saying. I'm not saying it's the fault of the cables yet. 

You wouldn't by any chance live near the NH area would you? Be happy to pay for your services to come out, LOL!

I do not. Sorry. That would make things a little easier wouldn't it. 😄 OK, so no spare XLR cables. Noted. Regarding the speaker wire that you have, we really only need to use one side (like either a plus or minus). Can you easily attach that to those ground terminals? Even if you just hold the wires against the ground terminals for a moment, while hearing the buzz, does it change the sound of the buzz at all?

So just wondering if you have any kind of wire stripper? Have you ever stripped the jacket off a wire? We’re definitely not going to take apart those nice XLR cables, but I’m wondering, before we go any further, what your skill level is here, so I know how to further direct you?

I will do the wire first thing tomorrow and report right back as soon as the experiment is completed

Not a problem. We’ll take it from there. One other thing, I think you mentioned that your XLR cables were intertwined with other cables? Was that correct? Were any of those ethernet cables? Also, if they’re still intertwined, would it be possible to physically separate at least one of the XLR cables from all other cables, and connect it (all by itself), and see if any buzzing exists?

I have stripped the jacket off of a wire before but I’m already over my head as soon as we get past connecting stuff

Thank you for being honest and admitting that. There’s only two more things I can think of at the moment that I’d like to try, and one requires a different XLR connecting cable (which removes the shield connection - pin 1 - on one end). I can actually make them myself, but let me see if I can find something on the internet for you. The other is I’d still like to hear if there’s any buzz with that ground wire connected between the two rear panel ground screws. Is there any small cable laying around (like a small extension cord) you could butcher and sacrifice? If you don’t have a wire stripper, with a little guidance, a scissors could probably perform the same function.

Do you own any other XLR cables? If so, have you tried them to see if they produce the same buzz as the Transparent's do? 

This would be an example of a device that lifts the shield on one end of the XLR cable. 

Female to XLR Male Ground Lift

If willing, it would be interesting to see if this connector would produce any different buzz sound results when plugged in using just one XLR cable.  

I did separate the XLR cables from any power cables and used a zip tie to keep them from separating and touching any power cables

Do you remember if that made any difference at all in the buzzing (even the slightest amount)?

do you just plug the XLR cable into that and then plug the whole thing into the Mac?

Correct, but of course I just recommend purchasing qty. 1 first. If you purchase from Amazon, you should be able to return it if it doesn’t eliminate the buzz (if you feel like going through the hassle). If it doesn’t work, it’s still a nice tool to have around in the future.

Like if it worked would I need 5 of those on each XLR cable I have?

Yes, if you still want to use the Transparent’s.

Just out of curiosity, roughly how long are the Transparent XLR cables? If you decide to purchase one of the ground lifter devices, I also wonder, just for comparison sake, if you should also purchase a cheap single XLR cable the same length as one of the Transparent Plus’, to see if just by chance a different cable design has an influence here (if by chance a friend doesn’t have a spare they could borrow you).

I’ll try connecting the wire for the ground between the Mac and Sim…

I’m not expecting this to change anything, as there should be no difference in ground planes between the two pieces of equipment, since they’re plugged into the same outlet, but you never know, and it’s still worth a try.

If we’re actually able to eliminate the buzz between the Sim and the Mac, it’ll be interesting to see what buzzes or hums pop up when reconnecting your pieces of equipment to the Mac, but let’s cross that bridge...

@russ69 I will admit, some people can describe hiss as buzzing, and confuse the two. So without me sticking my ear against kingbr’s speaker, I can only go on what he’s describing - that he hears a buzz.

what if I tried disconnecting the XLR’s and try RCA (I do have some of those Transparent as well actually though lower end of their line). Why not right?

GREAT idea!

Guess I could also order an el cheapo XLR too, because again why not?!

I would recommend it if you don’t mind.

I actually contacted Hosa the company and spoke with a gentleman in their tech support and ran this by him. He didn’t think their ground lift XLR would help as they are designed for microphones, but he admitted he did not know very much about home audio/HT.

It really depends on who you talk to. Some guys know where I'm going with this, and some don't.

I think the common denominator here is Revel speakers.

That may be, but kingbr already stated that there’s no buzz when disconnecting the XLR cables, with the amp on. I’m assuming the amp is not being trigger ON by audio. I hope that’s not the case. That would be absurd (and thankfully I don’t see that mode of operation option mentioned in the Sim manual).

I keep my Kismet amp on 24-7, my Hegel preamp as well. When I’m not going to be listening to music during most of the week. (I mostly listen Thursday through Sunday) I detach one of the XLRs. no buzz.

IMO, if you’re spending thousands of dollars on components and interconnects, you shouldn’t have to tolerate any type of noise or buzz. Isn’t that why you’re spending those big bucks in the first place? I’m sure kingbr could do the same (as what you’re doing), but I support his not wanting to, and I’m doing my best to try and help him out.

For over 3 decades I was a Chief Engineer for numerous radio stations. I learned the hard way how to eliminate hums and buzzes, of all kinds. Try connecting hundreds of pieces of broadcast equipment together (both balanced and unbalanced analog) in 14 studios (in one building), and see how many buzzes and hums you encounter (spoiler alert; there will be a lot). And if I do say so myself, there was rarely ever a buzz or hum I couldn't get rid of. 

If it were me, there’s no way I would tolerate a buzz, when spending thousands on home audio equipment. From looking at the manuals on line for the Sim and Mac that are involved here, the XLR outputs are of low impedance, and the balanced XLR inputs are of high impedance - exactly the way it should be, but that’s a very simple way of looking at this, as there’s so much more that goes into a decently designed piece of audio equipment. I’m having a hard time understanding why these two pieces of equipment can’t be happy (with no buzzing) playing nicely together (such technical talk).

@kingbr

Darn it, I just noticed this in one of the reviews of the Hosa ground lifter. The thought of this occurring just hit my brain, and only then did I dig a little deeper and realize someone else had the same concern as I. From a review of the Hosa:

I am VERY disappointed with this product. I bought two of these to use for my studio monitors when trying to debug ground loops, and discovered way too many problems for such a simple product:

== Wired incorrectly ==
First and foremost, this "ground lift" adapter doesn’t even lift the ground... The metal housing is electrically connected to the housing of each each end via the screws on either side. This would be less of a problem if it weren’t for the fact that the connector housing ground is connected to the ground *pin* on both sides. What does that mean? This is just a M to F XLR coupler. Which XLR cables never need.

I fixed this by opening them up, and de-soldering the wire that connects the ground pin to the connector housing. This was not a single mistake; BOTH units had this issue. Unless this is fixed, these are nothing more than a placebo.

I’m really sorry about this. This is frustrating, because I can make exactly what I need in a matter of minutes. I think the Pro Co model is more correct, as it looks like they’re disconnecting one end of the shell from the other (with shrink wrap), which breaks the metal shell ground connection (and pin 1 connection). Sorry, I know this is getting a bit technical now. The problem with the Hosa model, as mentioned above, is a ground connection is still taking place, which rides on the metal outer shell, even though the connection between pins 1 and 1 (on each end of the connector) are disconnected. This was something I was hoping the Hosa model didn’t do. Someone at Hosa designed their product poorly and incorrectly. Yeah, it happens.

Pro Co GLX In-Line XLR Ground Lifter Adapter

Checking stock, it looks like almost everyone on the internet is out of stock on this model (maybe because this one is designed correctly, and actually fixes problems). I’d call Parts Express to see if they can confirm that they actually physically have these on their shelf (the website says they have two in stock). @kingbr private message me with your address, and I’ll make one that I know works, does exactly what I want it too, and I’ll send it to you.

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.

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?

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.

There’s also a Mute Level adjustment (-40 dB, -20 dB). I’d also try adjusting that to see if that makes any difference in this noise you’re hearing.

To clarify, I'd also try turning ON the mute (trying either of the settings), to see if this has any effect on the buzz/hiss you're hearing.

@kingbr 

So the only reason I didn’t hear the buzz with the 1 cable plugged in was because it was the rear and I didn’t listen to that one speaker. As I plugged the 2nd rear in that’s when I caught on that as soon as the XLR cable is plugged back in the buzz comes back in that particular speaker/channel…

I did catch that in a previous mention, but thanks for mentioning it again, so everyone reading this can absorb it, if they missed it.

I have always found Transparent cables to be more “my taste” if you will. I have used several others but there just seems to be something extra once I bring in the Transparents.

...and I can respect that @kingbr. In my discussion of cable construction, I’m just wondering what amount of emphasis Transparent incorporates into their balanced interconnect shielding. Looking at their website, I see no display of it, or they don't boast about it. In your particular situation, it would be interesting to see how different XLR cables affect this noise that you’re hearing (possibly then related to shielding performance). I also can understand what @dilatante is mentioning about output gain from the Mac. It might be greater than your Marantz, which may be the reason behind you now hearing the noise with the Mac, compared to the Marantz.

Might a 20db attenuator be needed?

Keep in mind that these fixed attenuators will act like fixed volume controls. I don’t know how loud you play your system, but for every -dB of attenuation (5, 10, 20, etc.) that is used, you’ll lose that in volume when playing your system, so starting off with a -20 dB attenuator (or pad) might be a little high. Starting off with -10 dB attenuators, like @russ69 suggested, would probably be the better choice. Also, in your situation, and because of this noise, I would place them at the Sim inputs, and not the Mac outputs.

I also notice that there’s a Volume Limit adjustment in the Mac (choices are 60, 70 or 80). I might suggest switching between those (as they might be built in pads), and see if that changes anything. There’s also a Mute Level adjustment (-40 dB, -20 dB). I’d also try adjusting that to see if that makes any difference in this noise you’re hearing. It looks like the Marantz has these same setting adjustments.

Looking at the manual, this is the stated output level of the Mac (but at what volume level?):

Rated Output Voltage
2.5V Unbalanced Outputs (Main Zone)
5.0V Balanced Outputs (Main Zone)

Here’s the stated output for the Marantz:

Rated output: Unbalanced RCA pre-output : 1.2 V Balanced XLR pre-output: 2.4 V

I would hope that both would be 0.0V with no audio playing, or the volume turned all the way down.

What I like about power amps with volume/gain controls is that you can balance a system; not allowing a wide open amp when it’s not needed. I’m almost positive you would not be hearing this noise if the Sim had some sort of volume/gain control incorporated into it.

Don’t forget, we’re still interested in hearing if hooking up the RCA cables changes anything.

Good point @markmoskow. If it already isn't the case @kingbr, try turning off all lighting in your place, and see if this makes a difference. I also agree with @dilatante. There are sometimes trade-offs in the audio world. In your situation, you will probably be *slightly* compromising the performance of the Transparent's when inserting any other device in them (like the attenuators or XLR shield lifters). Only you can decide what you want to live with. If this was my setup, at some point I would have shorted pins 2 & 3 on one of the XLR cables (at the female end, while plugged into the Sim), to see how much of this is being picked up by the cable alone.