hum through my speakers - advice appreciated

[avg_audio_guy]

Hey everyone, could use some advice on how to deal with what I think is a ground loop hum pretty audible through my speakers--annoyingly audible at low listening levels.

Equipment:
Marantz SR7011 receiver
Aragon 4044 mkii amp
Willsenton R800i 845
Oppo UDP203 blue ray player
Roku HD one
LG TV
Tekton DIs
La Scala AL5s

When I was running the Marantz with the Aragon (pre-out for the R/L speakers) and the DIs, I didn't have a very audible hum (it was there, just very slight and not distracting from the listening position). But I have been starting to upgrade my system and bought the La Scalas and most recently the Willsenton.

I first got the LA Scalas and when I used them with the Aragon amp, no problem. When I got the Willsenton I replaced the Aragin with it. Initially I'm not sure I heard a hum (I think I only the Oppo connected). But since I hooked up the Willsenton to the pre-out of the Marantz, I get the hum.

The hum sounds like a 60Hz ground loop hum. It does not increase in volume if I adjust the volume on the amp nor the receiver. I've tried various power plug positions and made sure they're all on the same circuit. The hum mostly goes away (but not completely) without the Marantz plugged in. But I can plug in the Marantz to the Willsenton with the DIs and the hum is much less audible (maybe the efficiency of the La Scalas is amplifying the hum?).

I was thinking of buying a couple of the following items to remove the hum. Not sure if that is the best idea, any advice?
Jensen Transformers CI-1RR Audio Hum/Noise/Buzz Eliminator/ Ground Isolator

Not sure what I can do, nothing seems to work.

 

[lovinthehd]

Tracking down the actual cause of the ground loop hum and dealing with it would be ideal. What have you done to narrow down its origin?

Have you tried simply lifting the ground with a cheater plug to test if that's what it is on the Wilsenton? No hum without that amp?

ps An article on the general subject https://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

 

[TLS Guy]

Hey everyone, could use some advice on how to deal with what I think is a ground loop hum pretty audible through my speakers--annoyingly audible at low listening levels.

Equipment:
Marantz SR7011 receiver
Aragon 4044 mkii amp
Willsenton R800i 845
Oppo UDP203 blue ray player
Roku HD one
LG TV
Tekton DIs
La Scala AL5s

When I was running the Marantz with the Aragon (pre-out for the R/L speakers) and the DIs, I didn't have a very audible hum (it was there, just very slight and not distracting from the listening position). But I have been starting to upgrade my system and bought the La Scalas and most recently the Willsenton.

I first got the LA Scalas and when I used them with the Aragon amp, no problem. When I got the Willsenton I replaced the Aragin with it. Initially I'm not sure I heard a hum (I think I only the Oppo connected). But since I hooked up the Willsenton to the pre-out of the Marantz, I get the hum.

The hum sounds like a 60Hz ground loop hum. It does not increase in volume if I adjust the volume on the amp nor the receiver. I've tried various power plug positions and made sure they're all on the same circuit. The hum mostly goes away (but not completely) without the Marantz plugged in. But I can plug in the Marantz to the Willsenton with the DIs and the hum is much less audible (maybe the efficiency of the La Scalas is amplifying the hum?).

I was thinking of buying a couple of the following items to remove the hum. Not sure if that is the best idea, any advice?
Jensen Transformers CI-1RR Audio Hum/Noise/Buzz Eliminator/ Ground Isolator

Not sure what I can do, nothing seems to work.

What you need to do is unplug everything except the receiver and amps, but make sure only one is grounded. Now add the peripheral circuits one by one, and note which one or ones create the ground loop. Cable systems and Ethernet connections, are particular offenders where ground loops are concerned.

The trick is to identify connections that are not at true ground, which are completing the ground loop.

 

[OHMisback]

I've use the yo yo method too. Raise the cables up and down and see if it changes. It's a ground loop or a routing issue.. Sometimes placement of a new piece of gear disturbs the cable location with regards to AC cables, and ICs. The orientation of a piece sometimes causes issues with power supplies / transformers / speaker and IC cables.

Boutique coupling and decoupling caps are a prime source for noise too. They are put in backwards without regard for the trailing end of the cap wrap. It need to be pointing away from the positive, for noise rejection. They work just fine but are a nightmare in some audio racks, because of location..

Plug everything in several times, double and triple check if you're using any terminal ends (RCAs) with a twist to make them tighter. THAT is a biggie. They have to be tight. They will make noise because of it.. TIGHT is good, loose is bad..

Lifting the ground or jumper cables from piece to piece can tell you something too. A noisy LED is fun too.

SPS, laptop PS and cable wall warts can be noisy? GL suppressor will fix that or a separate dirty plug. I use 3 TripLite 2400s too. A maintainer and cleaner are never a bad idea. Unless you pay a fortune for one, that's on you, you sure don't need to. It's always the first thing I do. I protect my investment.

Vintage gear. 110vac on the button I always use a Variac and a maintainer for the Variac. New gear 120 or 220/240 on the button.

The wifes Jenson Imperials are 103 sensitivity at 16 ohms. No noise, tubes everywhere. Zero floor noise.. Routing!! is usually the trick for me unless a valve goes south.. They can drive you bonkers too.. I have a sniffer for the really tough ones, like DIY builds someone else built..

Carlson's Lab. Great designer and repairman.

I can get the schematic for one if you like.. It will find the stray noise no mater where it's at.

 

[PENG]

I first got the LA Scalas and when I used them with the Aragon amp, no problem. When I got the Willsenton I replaced the Aragin with it. Initially I'm not sure I heard a hum (I think I only the Oppo connected). But since I hooked up the Willsenton to the pre-out of the Marantz, I get the hum.

In your case, I think it would be very difficult to eliminate ground loop completely. Assuming it is not by itself a serious issue, then you should consider the following factors:

1) The Aragon amp's gain is about 25 to 26 dB, calculated according to published input sensitivity specs.

2) The Willsenton R800i 300B 845 amp has the following input sensitivity specs:

Product parameters:
Rated output power: 23W + 23W (RMS)
Machine frequency response: 12Hz ~ 35kHz (-1.5dB)
Input sensitivity: 280mV
Balance input: 280mV

Assuming that's the spec of the power amp section and that you are using it as a power amp only, then the calculated gain would be about 33.7.

If that's true, then it's gain is at about 8 dB higher and that could be one of the main reasons you are getting much higher noise.

3)The Klipsch's high sensitivity factor (you seem to know that well already)

The hum mostly goes away (but not completely) without the Marantz plugged in. But I can plug in the Marantz to the Willsenton with the DIs and the hum is much less audible (maybe the efficiency of the La Scalas is amplifying the hum?).

The La Scalas AL5 apparently has very high sensitivity, 105 dB, not sure if that's for per W or at 2.83V, but either way, anything that has sensitivity > say 93 dB could be considered higher than average.

So the 3 factors combined should explain why it would not be a good match between the SR7011, the R800i 300B 845 and the La Scala in terms of audible noise. You said hum, but I am sure you will hear hiss too if stay close enough to the speakers.

I was thinking of buying a couple of the following items to remove the hum. Not sure if that is the best idea, any advice?
Jensen Transformers CI-1RR Audio Hum/Noise/Buzz Eliminator/ Ground Isolator

If the hum is due to ground loop only, then it should work, but once that's gone you will likely hear hiss though that may not bother you if you sit far enough from the speakers.

Not sure what I can do, nothing seems to work.

You can also try a cheap solution too using the power amp's balanced inputs, assuming the balanced inputs of the Willsenton amp are wired according to good practice. If it doesn't help you can return it at no cost to you (I assume that (I could be wrong) if you buy from Amazon):

Amazon.com: Monoprice XLR Male to RCA Male Cable - 6 Feet - Black With E21Gold Plated Connectors | 16AWG Shielded Twisted Pair Oxygen-Free Copper Braid Conductors - Premier Series, 104777 : Everything Else

In theory, this cable should help lower ground loop hum to some extent thought not totally because the sending end (SR7011) is not balanced.

 

[DigitalDawn]

One of the first things I check is the coaxial cable going into your cable box. Unplug it and see if that gets rid of the hum. If it does, then Jensen Transformers has a solution:

https://www.parts-express.com/Jensen-Iso-Max-VRD-1FF-75-Ohm-Inline-Digital-CATV-Isolator-H-246-0121?utm_source=google&utm_medium=cpc&utm_campaign=12359859757&utm_content=117124193279&utm_term=&gadid=499069947558&gclid=CjwKCAjwquWVBhBrEiwAt1KmwnC8D4WVx4-nA0opHxM24qDxBqC9eeXp8UDMjeAcExSNi-B-5sWSVBoC240QAvD_BwE

 

[highfigh]

Amazon.com: Monoprice XLR Male to RCA Male Cable - 6 Feet - Black With E21Gold Plated Connectors | 16AWG Shielded Twisted Pair Oxygen-Free Copper Braid Conductors - Premier Series, 104777 : Everything Else

View attachment 56665

View attachment 56663

In theory, this cable should help lower ground loop hum to some extent thought not totally because the sending end (SR7011) is not balanced.

I doubt the Marantz is complementary balanced, so the fact that they even put XLR output jacks on it means they were catering to the fad. Their specs should show the output voltage and that should be definitely higher than the typical voltage for an unbalanced preamp output. Also, the Willsenton's preamp input sensitivity isn't shown, only the line in for sources but that's a different issue.

Isolate, separate and add devices as TLS posted and make sure the transformers aren't adjacent to the cables.

 

[highfigh]

One of the first things I check is the coaxial cable going into your cable box. Unplug it and see if that gets rid of the hum. If it does, then Jensen Transformers has a solution:

https://www.parts-express.com/Jensen-Iso-Max-VRD-1FF-75-Ohm-Inline-Digital-CATV-Isolator-H-246-0121?utm_source=google&utm_medium=cpc&utm_campaign=12359859757&utm_content=117124193279&utm_term=&gadid=499069947558&gclid=CjwKCAjwquWVBhBrEiwAt1KmwnC8D4WVx4-nA0opHxM24qDxBqC9eeXp8UDMjeAcExSNi-B-5sWSVBoC240QAvD_BwE

That should have caused hum before the new amp was introduced. OTOH, there aren't many absolutes.

 

[PENG]

I doubt the Marantz is complementary balanced, so the fact that they even put XLR output jacks on it means they were catering to the fad. Their specs should show the output voltage and that should be definitely higher than the typical voltage for an unbalanced preamp output. Also, the Willsenton's preamp input sensitivity isn't shown, only the line in for sources but that's a different issue.

Isolate, separate and add devices as TLS posted and make sure the transformers aren't adjacent to the cables.

No the Marantz SR7011 is not balanced at all! Hypex (I am sure it was Bruno Putzeys at the time) explained why an unbalanced to balanced (RCA to XLR) would still have benefits. The following Hypex article (likely written originally by Bruno Putzeyus has been posted a few times on forums, including Audioholics if I remember right, for you I search and found it for you:

I read the complete thing, along with others that touched on the same, and it makes sense to me:
NC400_04xx (2).pdf

Again as I mentioned, such RCA to XLR cable connections is not going to be as effective as XLR to XLR obviously but it is something the OP can try. If the effect is good enough, it is better than the Jansen gadget, ground lifting is not a good solution either, as Hypex also explained:

AN Dealing with legacy pin 1 problems (hypex.nl)
AN Amplifier signal input wiring (hypex.nl)

 

[avg_audio_guy]

Thanks for the responses everyone.

lovinthehd - I only have two sources plugged into the amp, the Marantz and the Opp. Both create a hum but the Marantz is definitely louder. Eventually I will put the Opp through a DAC with balanced output so I'm less concerned about the Oppo. The Marantz is already a two-prong plug and adding the cheater two-prong to the Willsenton doesn't remove the hum. Checking out the article tonight, thanks for the link.

DigitalDawn - I tried unplugging the cable and the hum is still there. Also, I do not have a cable box near this equipment, just streaming.

OHMisback - I'll try the cable positions. Not sure what you are offering in terms of a DIY build but I'l look at anything you send me.

highfigh/TLS Guy/PENG - thanks for the education, I'm learning a lot through this thread. Yeah, the Marantz has no balanced connection options. Also, the Willsenton only has one balanced input (I should have paid more attention to that when I bought it). Anyway, I'll probably pick up a RCA/balanced cable like you suggest PENG just to see what it does.

One other thing I think I am going to try is to attach a ground wire to the Marantz "earth terminal". There isn't a water pipe anywhere close (plus it's a finished basement and I don't want to tear into drywall. But there is a window within about 4' of the Marantz and I could run a ground wire outside that window to a copper rod I could sink in the window well area.

 

[Eppie]

One other thing I think I am going to try is to attach a ground wire to the Marantz "earth terminal". There isn't a water pipe anywhere close (plus it's a finished basement and I don't want to tear into drywall. But there is a window within about 4' of the Marantz and I could run a ground wire outside that window to a copper rod I could sink in the window well area.

Don't take the "earth terminal" literally. It's just a chasis ground that can be connected to the ground terminal of another device or receptacle. The center screw that holds the cover plate on a wall outlet also connects to ground and you can put a spade terminal under it (if the screw is not painted). I would caution you to measure for any voltage from that earth ground on the Marantz to ground on a wall outlet using a digital multimeter first. The plug should be polarized even if it's two pronged, but it's a good precaution.

 

[PENG]

Anyway, I'll probably pick up a RCA/balanced cable like you suggest PENG just to see what it does.

Keep in mind not all RCA to XLR interconnects are wired the same. There are the following 3 that I think are wired "correctly" for maximum benefits when used with XLR balanced inputs:

Benchmark RCA to XLRM Adapter Cable for Analog Audio - pin 3 to RCA sh - Benchmark Media Systems
ghentaudio --- A15 Canare L-4E6S RCA to XLR Interconnect Audio Cable
Male XLR to RCA Cable - March Audio

Since it may or may not work, or may only partially fix the hum with such RCA to XLR interconnects, I would suggest you try the Monoprice cable I linked before as it costs less than $25 per pair.

The Benchmark one costs more but still reasonable but they do seem like a better bet. Their website offers the following feature, and how it works:

SPECIAL WIRING TO REDUCE HUM AND INTERFERENCE:

• Back-referenced audio ground - for common-mode rejection
• Star-quad conductors - for magnetic immunity
• Dedicated shield connection - for immunity to ground loop problems
• RCA center pin to star-quad + to XLR pin 2
• RCA ring to star-quad - to XLR pin 3
• RCA ring to shield braid to XLR pin 1

HOW IT WORKS:
This adapter cable extends balanced wiring to the RCA connector using star-quad wire to maximize the effectiveness of the balanced input: One half of the star-quad ties Pin 3 of the XLR to the shield of the RCA connector. The other half of the star-quad ties pin 2 of the XLR to the center pin on the RCA. The braided shield ties pin 1 of the XLR to the shield of the RCA.

Using this special wiring, a ground-loop between the two audio devices will produce a current in the braided shield, but not in the audio signal lines. This keeps ground-loop currents out of the critical signal lines and greatly reduces the potential for interference. The separate connection from the RCA ground to pin 1 of the XLR provides a dedicated path for the audio ground reference. This wiring leverages the common-mode rejection of the balanced XLR input to reduce conducted interference.

To reduce magnetic interference, the audio signal is carried on two twisted pairs arranged in a star-quad configuration. This star-quad configuration provides immunity to hum-inducing magnetic fields produced by nearby electronic devices.

This cable provides the best method for directly interfacing an unbalanced output to a balanced input. Do not confuse this cable with similar-looking RCA to XLR cables and adapters!

Also, as mentioned in my previous post, not all XLR are wired the same, unfortunately so hopefully your Willsenton is wired correctly. If not then all bets are off. The connection issue has mainly to do with the "Pin 1", you can read the linked article for more info:

Pin 1 Revisited (ranecommercial.com)

One other thing I think I am going to try is to attach a ground wire to the Marantz "earth terminal". There isn't a water pipe anywhere close (plus it's a finished basement and I don't want to tear into drywall. But there is a window within about 4' of the Marantz and I could run a ground wire outside that window to a copper rod I could sink in the window well area.

Such approach rarely work.

 

[highfigh]

Thanks for the responses everyone.

lovinthehd - I only have two sources plugged into the amp, the Marantz and the Opp. Both create a hum but the Marantz is definitely louder. Eventually I will put the Opp through a DAC with balanced output so I'm less concerned about the Oppo. The Marantz is already a two-prong plug and adding the cheater two-prong to the Willsenton doesn't remove the hum. Checking out the article tonight, thanks for the link.

DigitalDawn - I tried unplugging the cable and the hum is still there. Also, I do not have a cable box near this equipment, just streaming.

OHMisback - I'll try the cable positions. Not sure what you are offering in terms of a DIY build but I'l look at anything you send me.

highfigh/TLS Guy/PENG - thanks for the education, I'm learning a lot through this thread. Yeah, the Marantz has no balanced connection options. Also, the Willsenton only has one balanced input (I should have paid more attention to that when I bought it). Anyway, I'll probably pick up a RCA/balanced cable like you suggest PENG just to see what it does.

One other thing I think I am going to try is to attach a ground wire to the Marantz "earth terminal". There isn't a water pipe anywhere close (plus it's a finished basement and I don't want to tear into drywall. But there is a window within about 4' of the Marantz and I could run a ground wire outside that window to a copper rod I could sink in the window well area.

By the original design, Low Impedance (LowZ) Balanced audio and consumer audio as we know it aren't really compatible because not only are the input and output inpedances different, the signal voltage is different. LowZ has much lower impedance and shielded, twisted pair wiring for allowing the placement of power amps where they're needed- close to the speakers. Old speakers, the type that existed when audio equipment began to be designed and implemented, didn't even have permanent magnets and almost all were installed in some kind of horn configuration, especially in commercial/industrial applications. The sources and preamp were located in a place that was practical, the power amps and speakers were placed where they were needed and the distance, again by design, could have been hundreds of feet away. That's very different from the way a consumer system is designed- sources near the preamp, which can be in the same device as the power amp but if not, it's usually not far away. The speakers are usually relatively close, too- if not, the power amp should be located closer to them. This is important because long speaker cable runs are prone to loss of signal and damping, especially in high powered systems like the ones used for concert PA systems.

It takes very little resistance on the ground conductor(s) to create a ground loop type hum- I would recommend disconnecting everything from the Willenton, other than the speakers. If you still hear hum, it's possible that an adjustment is needed or it may have a bad cap/bad solder joint.

Don't use the cheater, it may create a hazardous condition. Some designers don't ground the power supply in the same way as is needed here- if the power supply ground is lifted (which the cheater plug does), the chassis can become electrically 'hot' and if you touch that with one part of your body and something that's electrically grounded with a hand/arm/foot, etc on the other side of your body, it can be lethal.

 

[OHMisback]

The only question after seeing the gain issue is to HOPE Marantz or your amp doesn't comply to AES48 standard. PENG is hitting all issues with XLR to RCA. On paper a RCA XLR works to reduce gain. The next issue is to remove the rest of the floor noise. Personally a little bit of stray noise is WAY to much for me..

The DIY sniffer you have to make. Mine is a 1000 years old. BUT Mr. Carlson (look him up) repairing a pair of SixPacs Carys. He will show the noise detector in action on a stock pair of amps that he quietened down.

Happy hunting. BE Patient you'll get it. Keep notes if you have to.. Yo Yo the cables and check each piece of gear and its connections. Raise and lower the piece if you can. The sound will YO YO, add as little volume as you can. I work my systems until I can turn the volume to a minimum of 50%, without noise issues. Don't blow on a stylus doing that. Don't be heavy footed either. Finger on the remote so to speak.. LOL

Sure a lot of good information. I'm not use to this.

 

[trivema]

Hope not too late to weigh in here. I bought a Willsenton R800i 845 two years ago. It began to suffer a strong 120 Hz hum after about 9 months of running. I did all the regular hum diagnostics, clearly coming from amp power transformer. Did ground lift, DC on AC mains filter, lower gain 12AT7, 10 dB attenuators on input, still a hum audible from seating 7+ feet from Klipsch Forte IIIs when no audio signal. Also audible with low level listening when music passages go silent and there should be “black” background. Oddly hum louder during daylight hours than late at night. Also have Dennis Had Inspire KT-88 and a Cary 300B SEI LX-20 with no hum driving the Klipsch. Heck, even my cheap Oldchen EL34 into the Klipsch dead silent. Had several email exchanges with ChiniHiFi, basically “some hum characteristic always present with higher power tube amps.”

As fate would have it, my audio gear outlet blew (lightning hit while away?). I took the opportunity to have a dedicated mains line with real earth ground and high-end isolated ground audio outlets installed. Guess what, no more hum!! Not totally silent, there is slight residual hum when my ear is smack up against the mid horn, about equal to the Cary 300B. The Inspire and shockingly the Oldchen are dead black dark silent. But the Willsenton no longer has annoying hum that can be heard in between tracks, or when no signal. So hum problem solved. Back to high gain Telefunken, Amperex and Mullard 12AX7s. The Willsenton now holds its own up against my Cary 300B SEI LX-20 with $1,000 KR 300B XLS tubes designed to output 20+ wpc.

Moral of the story, I guess, is source power does matter and ”dirty power” is real. The dedicated mains only cost $500 to install and the outlet was $50. Cheaper than all the money I’ve spent on tubes and other audio tweaks. Give it a try and see if works for you.

 

[PENG]

Hope not too late to weigh in here. I bought a Willsenton R800i 845 two years ago. It began to suffer a strong 120 Hz hum after about 9 months of running. I did all the regular hum diagnostics, clearly coming from amp power transformer. Did ground lift, DC on AC mains filter, lower gain 12AT7, 10 dB attenuators on input, still a hum audible from seating 7+ feet from Klipsch Forte IIIs when no audio signal. Also audible with low level listening when music passages go silent and there should be “black” background. Oddly hum louder during daylight hours than late at night. Also have Dennis Had Inspire KT-88 and a Cary 300B SEI LX-20 with no hum driving the Klipsch. Heck, even my cheap Oldchen EL34 into the Klipsch dead silent. Had several email exchanges with ChiniHiFi, basically “some hum characteristic always present with higher power tube amps.”

As fate would have it, my audio gear outlet blew (lightning hit while away?). I took the opportunity to have a dedicated mains line with real earth ground and high-end isolated ground audio outlets installed. Guess what, no more hum!! Not totally silent, there is slight residual hum when my ear is smack up against the mid horn, about equal to the Cary 300B. The Inspire and shockingly the Oldchen are dead black dark silent. But the Willsenton no longer has annoying hum that can be heard in between tracks, or when no signal. So hum problem solved. Back to high gain Telefunken, Amperex and Mullard 12AX7s. The Willsenton now holds its own up against my Cary 300B SEI LX-20 with $1,000 KR 300B XLS tubes designed to output 20+ wpc.

Moral of the story, I guess, is source power does matter and ”dirty power” is real. The dedicated mains only cost $500 to install and the outlet was $50. Cheaper than all the money I’ve spent on tubes and other audio tweaks. Give it a try and see if works for you.

If the transformer is the one doing the humming, it will do so with nothing else connected, you plug it in you will hear it. In such cases, you can't do anything about it without either repairing the transformer, but there is not practical to do as it will most likely cost you less to replace it.

In the op's case, the hum is through the speakers so it is most likely a ground loop related issue. So, two different cases.

 

[highfigh]

I've use the yo yo method too. Raise the cables up and down and see if it changes. It's a ground loop or a routing issue.. Sometimes placement of a new piece of gear disturbs the cable location with regards to AC cables, and ICs. The orientation of a piece sometimes causes issues with power supplies / transformers / speaker and IC cables.

Boutique coupling and decoupling caps are a prime source for noise too. They are put in backwards without regard for the trailing end of the cap wrap. It need to be pointing away from the positive, for noise rejection. They work just fine but are a nightmare in some audio racks, because of location..

Plug everything in several times, double and triple check if you're using any terminal ends (RCAs) with a twist to make them tighter. THAT is a biggie. They have to be tight. They will make noise because of it.. TIGHT is good, loose is bad..

Lifting the ground or jumper cables from piece to piece can tell you something too. A noisy LED is fun too.

SPS, laptop PS and cable wall warts can be noisy? GL suppressor will fix that or a separate dirty plug. I use 3 TripLite 2400s too. A maintainer and cleaner are never a bad idea. Unless you pay a fortune for one, that's on you, you sure don't need to. It's always the first thing I do. I protect my investment.

Vintage gear. 110vac on the button I always use a Variac and a maintainer for the Variac. New gear 120 or 220/240 on the button.

The wifes Jenson Imperials are 103 sensitivity at 16 ohms. No noise, tubes everywhere. Zero floor noise.. Routing!! is usually the trick for me unless a valve goes south.. They can drive you bonkers too.. I have a sniffer for the really tough ones, like DIY builds someone else built..

Carlson's Lab. Great designer and repairman.

I can get the schematic for one if you like.. It will find the stray noise no mater where it's at.

10VAC won't matter. Power utilities are required to provide 120VAC ± 10% and tube amps aren't that finicky that hum will be caused by slightly higher voltage unless the designer didn't account for variations and that's definitely possible with the OP's amp.

 

[highfigh]

Hope not too late to weigh in here. I bought a Willsenton R800i 845 two years ago. It began to suffer a strong 120 Hz hum after about 9 months of running. I did all the regular hum diagnostics, clearly coming from amp power transformer. Did ground lift, DC on AC mains filter, lower gain 12AT7, 10 dB attenuators on input, still a hum audible from seating 7+ feet from Klipsch Forte IIIs when no audio signal. Also audible with low level listening when music passages go silent and there should be “black” background. Oddly hum louder during daylight hours than late at night. Also have Dennis Had Inspire KT-88 and a Cary 300B SEI LX-20 with no hum driving the Klipsch. Heck, even my cheap Oldchen EL34 into the Klipsch dead silent. Had several email exchanges with ChiniHiFi, basically “some hum characteristic always present with higher power tube amps.”

As fate would have it, my audio gear outlet blew (lightning hit while away?). I took the opportunity to have a dedicated mains line with real earth ground and high-end isolated ground audio outlets installed. Guess what, no more hum!! Not totally silent, there is slight residual hum when my ear is smack up against the mid horn, about equal to the Cary 300B. The Inspire and shockingly the Oldchen are dead black dark silent. But the Willsenton no longer has annoying hum that can be heard in between tracks, or when no signal. So hum problem solved. Back to high gain Telefunken, Amperex and Mullard 12AX7s. The Willsenton now holds its own up against my Cary 300B SEI LX-20 with $1,000 KR 300B XLS tubes designed to output 20+ wpc.

Moral of the story, I guess, is source power does matter and ”dirty power” is real. The dedicated mains only cost $500 to install and the outlet was $50. Cheaper than all the money I’ve spent on tubes and other audio tweaks. Give it a try and see if works for you.

Does "real earth ground" mean that your new circuit was grounded separately from the rest of the building? That's a bad idea and it violates the electrical code because it's likely that the rest of the electrical service's grounding isn't up to par and you could have more problems because of it. Grounding stakes and bonding can degrade, adding hazardous to the list of words that can be used when describing the wiring.