I recently purchased another users Eastern Electric Minimax DAC. It sounded fine at his house. He ran it strictly solid-state, no tube even installed. Also, he had aftermarket op amps. We reinstalled the default op amps and off I went.
At home I installed a Sylvania tube, plug it in, and now have a hum. I also bought one of Triode Pete's 12gauge power cords in the hope that might help, it arrived today, but no change with the hum. So, what to do?
I assume the first step is to remove the tube, and run it solid-state. If that's not it, then plug into a completely different outlet. Right now it runs into a PS Audio quintet with everything else except amp. The amp goes direct to wall outlet, a Leviton hospital grade, and Quintet goes to same outlet.
My fear is that after all the triage, if it still hums, could the problem be the reinstallation of the default op amps? Has anyone ever heard of this as a problem?
I'm feeding the DAC via the Duet receiver, using an AR optical cable.
And the hum is universal, it doesn't matter which source I select at the preamp, it just hums. The only way to terminate the hum, is to unplug the power cord from the DAC.
The one positive so far, well, after the overall improvement in sound the dac does make-has been the addition of Pete's power cord! :-P
So far all I've done is run Internet station through the dac, Radio Paradise, at 192 bits, but it's obvious the sound is up another notch. I'm in complete agreement with the following statement made about Pete's power cords in a different thread as follows;
"After installing Pete's cord, everything got a lovely warm glow to it, round and beautiful.. yet forceful. Some transient attack edginess was missing and replaced with more subtle transitions. It did make for a more musical sound overall. The mids seemed thick and rich which I liked. It wasn't mushy, just rounded."
I won't be able to speak to the loss of transient attack until I start running flacs through it which won't be for a few days, but I can already tell this is a keeper.
Thanks Pete!
We reinstalled the default op amps and off I went.
Hmmmm. Did you listen before or after?
Did you test the tube? Sounds like a bad tube. Does it hum when the SS output is used and tube still in the DAC.
Pull the tube out and run it thru the SS output.
Roy called me today and claimed no op-amps were rolled or that he never tried pulling the tube and only ran it in tube mode. Hmmmm.
Ground issue?
Congrats on your new DAC Gene, nice choice. Since the DAC plays music OK, then the opamps were installed correctly.
The tube should not cause any trouble, but pull it just to remove the variable. Once you find the quiet then you can start adding things back.
If this is EE DAC version 1 with volume control, connect the DAC directly to the amp. If it is version 2 use Duet to turn down the volume digitally, then connect to amp. By removing the preamp, if the hum is gone you exonerate the DAC and amp.
Hum is usually caused by resistance in the ground circuit. Ground is not absolute zero volts. Silent ground need only be the same ground voltage everywhere, but not necessarily zero volts. Resistance on ground connections causes voltage to vary in the ground circuit, causing current to flow and make the hum. Your mission, if you choose to accept it, is to find the source of resistance.
Most components do connect the signal and chassis grounds together inside the component, so that's how loops form between signal and power sides, they are both part of the ground circuit. The total ground circuit includes the whole system and the house wiring, not just the grounding inside one component. Their grounds all connect together so it is one big circuit. There is always voltage on a ground circuit, but if it's the same everywhere then it's silent. A few mV is common. But if there is any abnormally high resistance anywhere in the ground circuit then current will flow across that resistance and this current is the hum. It hums like AC because AC power supply is always grounded for safety. But even battery powered components can be a source of hum when connected by IC to an AC powered component.
Clean tight wires is first thing to check. Usually the resistance comes from temporary connections. These can be obvious, like dirty RCA plugs and jacks, or hidden, like two outlets with separate grounds. One outlet ground runs back to service box with dedicated ground wire. The other outlet is a shared circuit with wire stabbed outlets and a ceiling lamp with twisted connections. All those mechanical connections increase resistance, causing a ground loop in the house wiring when those two outlets are used simultaneously in a audio system that is interconnected with signal wires. Moving your ground testing system to one outlet cures this.
Any kind of antenna, cable or satellite cables will usually cause hum. Also think of whatever other changes may have happened in addition to the new DAC. Moving things around, changing plugs, etc. Often several changes are made at the same time that we don't realize. Simplifying the system to basic components removes those variables.
Rich,
That is by far the best definition of how ground loops are caused. You da man :thumb:
I really do think it is the tube though as Roy said he never had any problems with the DAC..
ET,
By chance do you have another 12au7 you can try in the DAC?
Did you listen before or after?
After, when I got it home.
Does it hum when the SS output is used and tube still in the DAC?
Yes. (Sorry, don't know who Roy is, you may be thinking of someone else)
Rich - great response - as for other wires, this is dedicated 2-channel, no other cables/wires.
To rest, thanks for insight, I will recheck/reseat all wiring, and I have 2 boxes of 12au7s, I just started with the Sylvania as it was the tube I started with in my Purity One pre.
Going to a 'how to pay for college conference tonight', on my return I'll try this 1st;
'Pull the tube out and run it thru the SS output.'
oops,sorry,I was confusing you with somebody else. :duh
'Pull the tube out and run it thru the SS output.'
Nope, no change like this.
Guess it's tims to get behind the rack and start re-wiring.
does the DAC have a three prong plug ?? If so try lifting the ground. Are you using one circuit for all components ? If using two different circuits a possible ground loop.
The EE DAC in my system would not lock until we flipped the CD ground switch. Hummed as well. It was not the tube in my case. Good luck.
charles
While playing with powercords this weekend I also pulled the dac far enough away from my rack o that I could plug it into an outlet on a different wall, 90% of the hum gone.
I tried a ground lift, but TWL makes it's ground prong so big I couldn't get it into the ground lift plug, and didn't want to force it.
Glad you found a good clue Gene. Sounds to me like bad connection(s) in the house wiring in that circuit.
To fix it, first determine what outlets, switches and ceiling lights or anything else is on the breaker of the audio outlet you want to use. With the breaker open, open up each of those junctions and improve all of the connections. If any wires are back stabbers, moved those to the side screws. If they are already screwed, then tighten them very tightly. If there are wire nuts, open them up and make sure all wire ends are even and all are twisted together and tight when capped. You will probably find some connections that need improvement, hopefully some of those will improve your ground and reduce the hum.
A dedicated line eliminates these wiring problems and their associated resistance (increased even when the connections are perfect.)
One loose connection on neutral or earth anywhere in the shared circuit can cause the problem you had. Because it went away with a different outlet it's probably not the audio gear cause. Maybe the other outlet is on a different circuit, or it is closer to the breaker and ahead of the bad connection. Use a voltmeter to check every outlet before you open it, and be careful. Consider upgrading the audio outlet with a Jena Labs duplex while you have it open.
I talked to Gene about a dedicated line. It will be a little work as his panel is in the garage but I think when can get it done. I looked and he has plenty of open spaces............Bill
That's awesome! Have fun guys.
Use 10ga romex instead of 12ga to reduce resistance, especially on a long run. 10ga is used for 20A circuit, but upgrading the breaker to 20A is optional, you probably won't need it and you could do that later. Better to spend on a nice outlet.
If by chance you end up doing two dedicated runs, they should be on the same leg, so all audio is using the same phase AC.
If you are going through the trouble of doing the labor yourself I would certainly put in two home run circuits, it's really not that much extra work. I always keep my power amps on their own breaker to make sure they don't interfere with any of the lower level equipment. (Although I do acknowledge that my amps are a bit more power hungry that most with the tube amp being 200 wpc and the two solid state amps being 500 wpc each. At least I only use one at a time in each system. :roll: )
And I agree with Rich, put in 20 amp circuits. They will perform better and you never know when you will come across a piece of equipment that requires one. For example the ARC VT-200 Mk II power amp comes equipped with a 20A IEC socket and cord even though the max rated current draw on th4 amp is about 12 amps. I can only assume they want more copper in the PC but the fact is if you brought one of these home and only had a 15A receptacle available you would be out of luck. The incremental cost of running 20 vs 15A circuits is very small in the grand scheme of things and it can easily save you from some future headaches.
Quote from: richidoo on May 20, 2012, 07:47:46 PM
That's awesome! Have fun guys.
Use 10ga romex instead of 12ga to reduce resistance, especially on a long run. 10ga is used for 20A circuit, but upgrading the breaker to 20A is optional, you probably won't need it and you could do that later. Better to spend on a nice outlet.
If by chance you end up doing two dedicated runs, they should be on the same leg, so all audio is using the same phase AC.
Rich that I didn't think off. We had talked about 10 ga wire and 20 amp circuits and while I wouldn't call it a long run it surely isn't next to the panel.
Could we use 10/3 wire or would it be better to run 2 separate wires. Are 2 neutrals wires a plus ??
Hi Bill,
By same leg, I mean same buss and same phase. There are two hot buss bars inside the service panel, each one carries 120V in opposite phase.
(http://0.tqn.com/d/homerepair/1/5/D/0/-/-/bus_bar.jpg)
A double pole circuit breaker takes up two breaker positions in the panel and connects to both busses, adding together the two legs, giving you 240V on the line.
A single pole breaker only connects to one hot buss, only takes one (or half) position and only provides 120V service. A single pole breaker can use either buss, but not both. Since the two busses are opposite phase, two separate 120V lines could be either in phase or opposite phase depending on the panel position of the circuit breakers. The two opposite phases should not be mixed together in the audio system. Choose breaker positions so that both circuits use the same buss and have the same phase.
Breakers alternate phase through vertical positions in the service panel, while breakers on the same horizontal row are the same phase.
Quote from: pumpkinman on May 21, 2012, 03:59:57 AM
Could we use 10/3 wire or would it be better to run 2 separate wires. Are 2 neutrals wires a plus ??
You must run two separate lines for two separate circuits. 10/3 is just for complex wiring like multiple switches, switched half outlet on one circuit. It's not meant to carry two separate circuits. Use two runs of 10/2, one for each breaker.
Neutrals sense a fault and trip the breaker, so you don't want to do anything weird with them. Each circuit gets one breaker, one hot, one neutral and one ground.
I assume you know what you're doing Bill, but in case you are new to this remember you can do most of the work of pulling the wires under the house and then have an electrician hook up to the panel for <$100.
You cannot get a better explanation than what has been provided by Richidoo.
The benifit of dedicated circuits and say Jena or Hubbel Cryoed duplex receptacables is going to make you real happy.
Using one for the digital and the other for the amps and Pre.
If and when completed try an Uberbuss. Others here are using the Uber and are very pleased with the outcome. Have fun trying.
charles
Quote from: richidoo on May 21, 2012, 05:29:14 AM
Quote from: pumpkinman on May 21, 2012, 03:59:57 AM
Could we use 10/3 wire or would it be better to run 2 separate wires. Are 2 neutrals wires a plus ??
You must run two separate lines for two separate circuits. 10/3 is just for complex wiring like multiple switches, switched half outlet on one circuit. It's not meant to carry two separate circuits. Use two runs of 10/2, one for each breaker.
Neutrals sense a fault and trip the breaker, so you don't want to do anything weird with them. Each circuit gets one breaker, one hot, one neutral and one ground.
I assume you know what you're doing Bill, but in case you are new to this remember you can do most of the work of pulling the wires under the house and then have an electrician hook up to the panel for <$100.
I know how to run and wire to the breakers and outlets. I assumed that you would need 2 runs. I have a outlet tester to check things when I'm finished
(http://1510365blog.files.wordpress.com/2008/01/how-to-check-electrical-receptacle-polarity-2.jpg)
Thanks Charles!
Bill I figured you knew what you're doing and just using your creative thinking to save Gene some money on wire. :thumb:
Sharing two separate circuits on one 10/3 wire run doesn't meet code because the single wire can't handle the heat of two 15A circuits at full tilt inside one wire jacket. It would melt the insulation and short. Maybe not now with small audio loads, but maybe later with vacuum cleaner and space heater running, or when Gene hits the jackpot and upgrades to Melody 100W 845 monoblocks. :thumb:
Quote from: richidoo on May 21, 2012, 10:34:28 AM
Thanks Charles!
Bill I figured you knew what you're doing and just using your creative thinking to save Gene some money on wire. :thumb:
Yes I was, 250 ft of 10/2 is $228 at Home Depot :shock:
Yeah, that's a long run. Mine is only 60 feet, but I thought that was long... Cost me $75 installed when I built the house in '05. Now I wish I got two! But in honesty, one is all I've ever needed. Two would be more convenient, but I never needed more power.
Just make a single dedicated run to two duplexes in a double box, or make a shared circuit with just the two outlets spaced apart. If the connections between the two outlets are good it will make no difference. Or go crazy and not cut the wire, just strip insulation and bend around the screws, then carry on to the next outlet. A lot more work, but if you're cuckoo this is what is required. :rofl:
I'm thinking each run would be about 75'. So 2 ~100 ft rolls would do.Not sure if they sell 150 ft rolls.
ANT online has 250' for $155 plus what ever shipping costs
http://www.globalindustrial.com/p/electrical/wire-cable/wire/nmb-cable-with-ground-white-10-2-awg?utm_source=google_pr&utm_medium=cpc&utm_campaign=Wire-google_pr&infoParam.campaignId=T9F&gclid=CPTHjYOxkrACFUdN4AodXkbMpg (http://www.globalindustrial.com/p/electrical/wire-cable/wire/nmb-cable-with-ground-white-10-2-awg?utm_source=google_pr&utm_medium=cpc&utm_campaign=Wire-google_pr&infoParam.campaignId=T9F&gclid=CPTHjYOxkrACFUdN4AodXkbMpg)
I simply love the way you guys are spending my money! :shock:
Quote from: etcarroll on May 21, 2012, 03:19:31 PM
I simply love the way you guys are spending my money! :shock:
What the Fark are friends for Kemosabe
Well, since there seems to be a plan, but not one happening this week, and I'm on the road following 3 weeks, I broke down and put a ground lift plug on the 12 Plus, and reseated it in the Quintet.
Hum 100% gone.
But I'm not comfortable living like this.
Bill, you really don't need two lines. It is overkill.
And before you whip out that AMEX Black Card, be advised that the dedicated line does not guarantee the hum is cured. It is just a likely cure based on how I interpret your symptoms. I could be full of shit (there I said it... :-P) or the loop could be within your system.
Many people run a lifter on the preamp or source permanently, especially with tubes involved. So it is a possible avenue to consider. The safety ground is probably still intact through the interconnects anyway, that's why it hums. But you shouldn't rely on that as a safety ground.
Quote from: richidoo on May 21, 2012, 04:25:54 PM
Bill, you really don't need two lines. It is overkill.
And before you whip out that AMEX Black Card, be advised that the dedicated line does not guarantee the hum is cured. It is just a likely cure based on how I interpret your symptoms. I could be full of shit (there I said it... :-P) or the loop could be within your system.
Many people run a lifter on the preamp or source permanently, especially with tubes involved. So it is a possible avenue to consider. The safety ground is probably still intact through the interconnects anyway, that's why it hums. But you shouldn't rely on that as a safety ground.
Listen being full of shit is my job and if your going to take over
you must ready to be full of it. The final say is up to Gene but a dedicated line could only help matters. I'd be happy to help Gene because he's such hapless fellow :rofl: :rofl:
I guess I'm not ready to take over completely yet. Just wishful thinking by a rank amateur, and I apologize for moving on your territory, Bill.
Yes, dedicated line is very good. But if it still hums, remember, you can always use the ground buster on the dedicated line too.... :rofl:
Bill...
QuoteI'd be happy to help Gene because he's such hapless fellow
Plus....It's his birthday.... :beer:
:duh
Quote from: lonewolfny42 on May 21, 2012, 06:15:13 PM
Bill...
QuoteI'd be happy to help Gene because he's such hapless fellow
Plus....It's his birthday.... :beer:
I treat him no better than my own family. I forget their birthday's too. :duh
Eureka !!!!!!! :D
Richidoo's friend Sol proposed a fix for my hum - and it works!!!
Life is once again good.
Quote from: etcarroll on July 09, 2012, 10:44:49 AM
Eureka !!!!!!! :D
Richidoo's friend Sol proposed a fix for my hum - and it works!!!
Life is once again good.
What was the solution?
Adding 2 small diodes soldered together with a resistor bridging them, then adding that tidy package to the IEC - at the ground line of IEC I believe.
The DAC was silent in my system before mods, so there's nothing wrong with the EE DAC. But there is a loop between Gene's DAC and the preamp wethinks. There are probably other ways to fix it, but this was mentioned as the cheap and easy way based on Gene's description of the problem. The hum is gone with a cheat plug, so Sol designed a simple circuit to go between IEC ground pin and chassis that conducts above 1 volt for safety, but does not conduct below that, to stop the hum in mV range. Quiet and safe, and many big name manufacturers use this circuit. Now Gene's DAC is hum proof in any system!
Nice. Good to know for future reference.