@winoguy17 , that's a good thought. My SS amp has high gain and was boosting the noise level previously on a shared dedicated line. Since I moved my system to a subpanel with a line dedicated to analogue, the noise floor has been greatly reduced.
As a test, I hooked up an old Kenwood amp with much lower power and the noise from the mains was still present.
@yakbob , I tried a Jensen transformer between preamp and amp, but I have an Atma-Sphere OTL pre and the transformer ruined the sonics. I've seen some comments by Ralph(atmasphere) where he says putting a transformer inline with an OTL device can have unpredictable or negative results.
@lak , I like the concept of the iso transformers and looked at how you've implemented them. That type of setup would work in my basement, but cost is a consideration. I will ask my electrician about it and show him your pics, thanks.
|
You may be right, gdnrbob. I think the surge/ noise reduction unit was about $700, but I have found some online for less. I get the feeling the electrician will only install the brands that his company uses. He had a binder showing the different units available.
However, he was fine with me providing the Romex and Hubbells for the installation.
@lak , I'm in Philly, PA (a row home). How did you determine the rating of the transformer (5 KVA) for your needs?
@don_c55 , thanks, but I've got a limited budget and I've already invested in Blue Circle and Brickwall PC's plus some Blue Circle line filters.
|
Thanks @ivan_nosnibor , I'll look him up.
I don't believe it's component related, but tomorrow I plan on removing all power conditioning and surge protectors to eliminate extra circuits and cables.
I swapped the SS with a tube amp tonight and the same amount of noise was audible.
|
Lowrider, my understanding is that a sub-panel should have hot, neutral, and safety ground all wired back to the main service panel
Al, that's what I thought. I asked the electrician about code, and he said it meets code and this is how he wired his house for a high-end HT system. He said not having a ground wire back to my circuit box containing old, poor quality wiring would cut down on noise. I thought, finally I found an electrician who appreciates good audio. One issue about my main circuit box is that it is a mix of new, updated wiring and old wire and breakers from the previous owners. Maybe @jea48 can weigh in regarding adding a subpanel. I'll try using only one line, that's a good idea. This is an upgrade for me and I wanted to get it right. I used Romex 12/2 with Hubbell 20A brass duplex receptacles grounded (not self-grounded). Romex was run from subpanel taking separate routes to the receptacles, same length. |
I assume neutral and safety ground are not connected together at the
sub-panel, which would be a definite code violation and would create
numerous potential safety hazards, and possibly noise problems as well.
Given that assumption, the main purpose of a safety ground is defeated
by the approach you've described. Especially if there is a significant
distance between the ground rods of the two panels, and/or the soil in
between them is dry. @almarg , Now I'm confused and will call the electrician tomorrow. As I understand it, the hot for the subpanel is connected to the main circuit panel. The neutral and safety ground are connected to the subpanel. The main panel has a 8' grounding rod into the earth, the subpanel has a ground rod into earth about 3 feet away. Here's what I can confirm; using only the amp and preamp plugged into the same dedicated line, I get loud 60Hz hum when I power on the Atma-Sphere UV-1 preamp. When using a cheater-plug, I hear low-level hum. This happens on both receptacles/dedicated lines. I have also used cheater-plugs on both components. BTW, no sources or power conditioners are being used. I checked for continuity with a multimeter between chassis and IEC connector safety-ground pin and connection is OK. Performed this on both the amp and preamp. This SE preamp has always caused hum with every amp I own. This is the noise/hum that I've been hearing. |
@jea48 , Thank you so much for taking the time to share what I consider expert advise and knowledge.
I'm going to email your information to the electrician and we'll find out what is really going on. (I'm hoping that I'm wrong about how the subpanel is wired).
And @almarg , you're always a key resource for any audio issues I have.
What do you fellas think is the issue with the Atma-Sphere preamp (single ended)? It has always caused hum in my system.
It is designed with star-grounding and I confirmed that the safety ground is tied to the chassis. (also confirmed the grounding on the amp). This hum (which sounds like a ground-loop) has been constant even during the time I had the original dedicated line. Before that, I had a Rogue pre with no issues.
Your thoughts?
|
did you get construction permits for this project? Was the work inspected by your town's electrical inspector? @cleeds , I just noticed your post. In Philadelphia, a permit is not required for an electrical addition or upgrade in a residence. The law states that an inspection is required at the time a house is being sold. |
@almarg ... Thanks, Al. Can always count on you. I thought about using shorting plugs a while back, but now I can't remember if they can be used on the UV-1. I'll reach out to Ralph next. What if Lowrider57 has lost a power supply cap or has a cracked solder joint in one of his component's Yes, it's possible that there is an internal problem. I did use a Jensen, following your recommendation, on the preamp output and the sonics were so terrible I quickly removed it. Ralph has stated many times how adding a transformer inline with an OTL component can have a negative effect, and wow, he was not kidding. So I can't remember if it corrected the ground loop. The Jensen did perform well on the source which was involved in the ground-loop in my system. If you recall, my Sunfire amp was designed with the signal and the safety ground tied together, which threw a wrench into the entire system. I now have a tube amp, properly grounded, so there should be no ground-loop. I can't confirm that, of course, until the electrician verifies that his wiring is correct. Many thanks to you and Jea48, Jim |
Cleeds, that's interesting. The company that I use has about 20 electricians on staff. They come to the house to give a free estimate, then return about a week later to do the work. Perhaps they get the necessary permit before starting the job. Maybe someone in their office does this.
This the third time they have done work for me; an upgrade with new breakers, lines and receptacles, then my first dedicated line after I entered this hobby, and the latest work 2 weeks ago. |
who performs an inspection of the property on behalf of the buyer. If the inspector determines that work was done without proper permits and inspections, it's a huge red flag that can not only delay a sale, but require that permits and inspections be done after the fact. Was electrical work done behind Sheetrock that's now been sealed and painted? The electrical inspector can insist that the wall be cut open to reveal the work and prove that it was done in compliance with code.
This part is true in my city. The difference is that the inspector is hired by the buyer and his real estate agent. As I stated earlier, I hope I'm wrong about how the subpanel was wired. I asked him at the end of the job, maybe I misunderstood. One thing I do remember is that he said new code requires 2 grounding rods. The name of the company is Generation 3 aka GEN 3 in Philly. Started out as a son, father, grandfather business with very affordable rates. Not so anymore. I will report back with my findings. |
Oh, and @jea48 , I have a 2 phase panel with 60A service (small row home and still meets code). Electrician installed a 60A Double-pole breaker in the main panel, then ran wire in a conduit to the subpanel.
It's about 5" to the side of the main.
|
I heard from my electrician and all is good. I copied the instructions posted by @jea48 and @almarg and sent an email. He said that the additional wiring of the new panel matches jea48's information. One exception is that he believes the 2nd grounding rod should come from the subpanel, rather than 2 rods from the main circuit box. (new code requires 2 ground rods per residence). So, Jea and Al, thank you again for the time you spent dealing with this issue. @cleeds , the project wasn't inspected by a city official before it was put into use. Inspection is done at the time a house is being sold during the closing process; Title search, Home Inspection, and Pest Inspection are required. The buyer may use an attorney or a realtor for the closing process and must hire the certified building inspector. As far as permits, I saw the law that you posted, and I know it applies to construction or an addition to a residence, but my neighbor and I both have had electrical and plumbing work performed without a permit from a licensed contractor. |
Many thanks, @whart . I agree that @jea48 has the knowledge that crosses that boundary between electrician and electronics. All that and I bet he can cook.
|
Question for @jea48 or @almarg ... The sub panel feeder Hot/s, neutral, and safety equipment ground conductor are all fed from the same main panel.
The sub panel feeder neutral conductor/neutral bar can not be bonded, connected to the sub panel metal enclosure or the equipment ground bar. The feeder neutral bar must be left isolated/insulated from the metal sub panel enclosure. (Green bonding screw or neutral bonding strap that came with the panel discarded.)
If the the feeder neutral conductor/neutral bar is bonded to the enclosure/equipment grounding conductor/equipment ground bar then the equipment grounding conductor will be connected in parallel with the feeder neutral conductor. What happens then is the equipment grounding conductor will carry neutral current back to the main electrical panel, or where the service neutral is bonded, connected to the enclose, equipment ground, and earth.
Not good for the equipment grounding conductor to carry neutral current. If the subpanel (containing breakers for 2 lines) takes a feed of hot, neutral, and safety ground from the main panel, are these 2 new lines truly dedicated? IOW, by tying in to the main panel (which may have shared neutrals and grounds), is there a chance of causing a ground-loop in the new lines originating from the subpanel? |
Tying the neutral and grounds together at the main panel is required by code and helps prevent ground loops. Thanks, fellas. Good to know that this helps prevent ground-loops. Also relieved that my electrician confirmed his work conforms to code and matches Jea's instructions. BTW, each dedicated line travels separately to a receptacle with the ground wire attached to the outlet...not self-grounded. |
@falconquest , I've been following the balanced power threads and it seems like the way to go. I don't have the funds to do it now, but I see it in my future. Would be much better than using filters and grounding blocks.
Thanks.
|
After much troubleshooting I can confirm that both dedicated lines are extremely quiet. My preamp is emitting a low-level hum (even through a power transformer). Swapping preamps proved that the mains had no noise to speak of.
So I will address this issue with the manufacturer, then hopefully move on to some "black-background" listening sessions.
Thanks again to all.
|
Yeah, he's a good guy. When he saw that I bought the Romex at Lowes, he said "save your money and return it, I'll use my wire n/c.
|
@falconquest , a couple of questions...
Can an analogue device plus digital be plugged into a balanced power conditioner w/o any digital noise transfer? Example, I know for a fact that my PSA Perfectwave bleeds digital noise back to the mains.
Secondly, what happens if an amp on a separate AC line is tied to the preamp in the balanced power unit?
|
