Hum (Ground Loop?) at Speakers
Comments
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@KennethSwauger - when you say reestablish preamp/power amp connections, do you mean put the jumpers back on the "pre-amp" & "main in" RCAs?
Here's a picture of what the back of my Carver looks like.
This is my lack of electronic experience showing... I assume you mean connect the Carver to the amp from the Tape Out on the carver to the R/L RCA inputs on the amp, making sure the jumpers are back on the Pre Out/Main In RCAs, correct? If not, I may need a little clarification! -
@KennethSwauger - when you say reestablish preamp/power amp connections, do you mean put the jumpers back on the "pre-amp" & "main in" RCAs?
yes I believe that is what Ken is asking.
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Yes, that is correct.
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That's what I thought! Just wanted to be 100%. I'll try this later and report back.
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I didn't see anywhere above, but do you have a cable/dish box connected to the receiver? I had a ground loop similar to what you're describing when my cable box was connected to my receiver.PS Audio Stellar Gain Cell DAC/Preamp
Denon DVD 2910
Quad 12L Active Monitors
Marin Logan Dynamo 700W -
No, this is a stand-alone 2 channel system. Comcast Cable is connected in the HT.
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-- but you do get the hum/buzz without the cable connected, correct?
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Correct - the buzz is there without cable or anything else connected to it. Just the amp and pre amp.
This is an entirely new and separate 2 channel system. There is no cable nor will there ever be cable connected to it. -
Try turning off the auto eq if it’s on.Oh, Listen here mister. We got no way of understandin' this world. But we got as much sense of this bird flyin in the sky. Now there is a lot that bird don't know, but it don't change the fact that the world is happening to him all the same. What I am tryin to say is, is that the course of your life, well its changing, and you don't even see it- Forest Bondurant
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I didn’t catch what your using as a source, but I know that both my tablet and my laptop have EQ presets in them, and some of them on both produce a very loud hum. Just a thought.
EDIT: Oh nevermind that isn’t relevant found where you listed your gear
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Do you have continuity from the center ground IEC pin to any of the outer shields of the RCA terminals?
I checked continuity from the center hole to the outer shields on the RCA terminals for the pre outs. No continuity.
Ken - I put the jumpers back in the pre-out/main in and ran RCAs from the Tape our to the amp - NO BUZZING! I do get a faint hissing, as I would expect since the volume is not controllable. I connected my phone to try and it played fine.
So, no buzzing using Tape Out to the amp.
I reconnected using the pre-outs again and toggled through all sources as well as Tape Monitor on/off. Buzzing all the time. -
Jeremy - there is no EQ on this receiver. There is Sonic Holography, but I don’t think it works anymore. I toggled it on and off and no change.
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Do you have continuity from the center ground IEC pin to any of the outer shields of the RCA terminals?
I checked continuity from the center hole to the outer shields on the RCA terminals for the pre outs. No continuity.
Ken - I put the jumpers back in the pre-out/main in and ran RCAs from the Tape our to the amp - NO BUZZING! I do get a faint hissing, as I would expect since the volume is not controllable. I connected my phone to try and it played fine.
So, no buzzing using Tape Out to the amp.
I reconnected using the pre-outs again and toggled through all sources as well as Tape Monitor on/off. Buzzing all the time.
So what does this mean in layman's terms? -
In all likelihood you'll have to make the connections using a "Y" cable with a male plug on the base and a male plug on one of the branches and a female connector on the remaining branch. Then use the "Y" cable to make the original connections between the preamp out and power amp input. This will give the remaining female connection to provide a connection to the external amp.
There is a second possible solution. You might have to run a separate ground wire from the preamp (use the phono ground connection) to a grounding point on the amp (usually a chassis screw). -
OK, tried one more thing.
I moved the amp and Carver into the Theater, and reconnected. As expected, I still had the buzzing...
BUT, I then tried using my Marantz AV7702 as the pre. I connected to the amp using the same RCAs. Buzzing all but gone! It’s very faint (I mean you have to literally put your ear right against the mid driver). Whereas the buzzing with the Denon and Carver was clearly audible even in another room.
So, it looks like the pre amps without grounded plugs (Denon and Carver) cause the buzzing. The Marantz (with the 3-prong grounded power cable) is practically silent.
Don’t know if there’s a temporary resolution or not. It is my ultimate intention to eventually upgrade to a tubed or hybrid pre amp down the road. Just hoping to resolve the annoying buzz in the meantime. -
KennethSwauger wrote: »In all likelihood you'll have to make the connections using a "Y" cable with a male plug on the base and a male plug on one of the branches and a female connector on the remaining branch. Then use the "Y" cable to make the original connections between the preamp out and power amp input. This will give the remaining female connection to provide a connection to the external amp.
There is a second possible solution. You might have to run a separate ground wire from the preamp (use the phono ground connection) to a grounding point on the amp (usually a chassis screw).
Thanks Ken! I don’t have any Y cables configured that way... I could try a grounding wire. I did try clip leads from the phono ground screw on the pre amp to the case of the amp, and it didn’t help. It’s possible it wasn’t a good grounding point on the amp... I did NOT connect to a chassis screw, but did touch the lead to different metal parts of the amp. What would be considered a “chassis screw” and hence a definite grounding point on the amp? -
Well, it certainly LOOKS nice...
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Usually any metal screw near the back panel is a ground point, but each component can be different. Also the outer grounding part of the RCA socket should be ground. However it sounds like you've already tried this.
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FWIW, the B&K PT3 pre I used to run with each 125.2/200.2 didn't have a three prong plug. I think Ken is hitting it...Remember, when you're running from something, you're running to something...-me
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I checked continuity from the center hole to the outer shields on the RCA terminals for the pre outs. No continuity.
I don't know the schematic of that preamp, but you may want to check the inside for a loose or broken ground wire. Maybe someone else can chime in on the lack of continuity there.
Let me edit, I'm not referring to the center hole of the rca, but the ground of the preamp...doesn't appear to have a 3-prong IEC. -
Ken - I have only tried grounding the pre to the amp by clipping the lead to the ground nut on the pre and basically touching the other end of the lead to various metal parts on the amp. That didn't seem to eliminate the buzz.
It looks like my only remaining option is to try the Y splitter. However, I can't even find a splitter that is 1 male to male/female (i.e. male at the base of the Y and 1 male / 1 female at each 'branch' of the Y). Granted, I just did a quick google search and Amazon search.
Am I correct in the following? Take the male base of the Y splitter and plug into the "pre-out" on the pre; plug the male from the top of the Y and plug into the "main in" on the pre; connect a standard RCA cable to the last female end on the top of the Y to the RCA in on the amp. Repeat for L&R channels. I assume a standard (1 female to 2 male) would not work, correct? -
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That makes more sense, LOL! I misread your original recommendation - should have re-read...I don't know the schematic of that preamp, but you may want to check the inside for a loose or broken ground wire. Maybe someone else can chime in on the lack of continuity there.
Let me edit, I'm not referring to the center hole of the rca, but the ground of the preamp...doesn't appear to have a 3-prong IEC.
I just saw "center...to any of the outer shields of the RCA terminals". I missed the part about the ground IEC pin. It was a long day yesterday...Do you have continuity from the center ground IEC pin to any of the outer shields of the RCA terminals?
I'll double check this evening. -
The one female to 2 male will work just fine. Regardless of how the signal looks like it should flow, all the center pins are connected & all the outer shields are connected. I do something similar in one of my boy's set-ups to run a powered sub. Male to the pre-out, male to the amp-in, & female to another cable going to the sub.
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Thanks Dave. I'll try this. I think I have some splitters at home to at least give it a try.
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Tried a couple more things. I checked continuity from the outer shields of the RCA terminals to ground and there IS continuity.
I also tried an RCA splitter from the pre out to main in and connected the tail to the amp. That, unfortunately, did NOT eliminate the buzzing...
Not sure what more to try. -
Another amp?
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You probably should telephone the Jensen Transformer company: (818) 374-5857
and describe what you've experienced. It might require a line level ground loop isolation device. -
Mike - I tried another amp with the Denon and Carver pre-amps and get the same buzz. With my Marantz pre-amp (with a three prong plug) I get no buzz.
A pre-amp upgrade is next on the list, so hopefully it resolves the issue. Just looking for a temporary resolution.
Ken - I’ll give Jenson a call and see if they can help in the interim.
Thanks to everyone for all the help and suggestions. -
Are you able to measure any DC voltages between the ground side of the preamp and the ground of the amp when an RCA connection is made? Or between the ground of the preamp and the chassis of the amp? Really just between either the phono ground and any place else on either chassis with an RCA cable joining them?
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... or AC.
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