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500 rack hum testing
Old 14th April 2019
  #1
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500 rack hum testing

Have a BAE 11 space and Daking 500 pre. Have hum with the Daking, but no hum from the empty BAE. Which is the culprit? I don’t have another unit to check and I’m hesitant to buy one as I’m worried I’d find out it also has a hum with the BAE.

I had this problem a few years ago with a 73jr and a bento rack and found it was the pairing. The pre worked fine in another rack and no other module had a hum in the bento.

I really wanted to fill the BAE rack up, but now I’m thinking return the rack, sell the daking and steer clear of 500 series, but I love the idea a of less space.

Any suggestions?
Old 15th April 2019
  #2
member no 666
 
Fletcher's Avatar
It depends on the hum... is it a straight hum at your local voltage? Under your name it say you're from Taipei City, if I remember correctly, Taiwan is all 110v from the wall. Is the hum you're hearing at 110Hz, 220Hz, 330Hz?... or is it more of a higher frequency "buzz" [there are a LOT of different hums... sometimes its just easier to teach the damn thing the words ].

If its a grounding thing [as in two or more paths to ground that have potential energy between them], then you just have to hunt down the grounding thing [there are only 6 combinations to try lifting one or two of... audio input, audio output, electricity from the wall].

If its a higher frequency "buzz" that opens up a whole new can of worms... as it could very well be "air born"... as in "stray field" related... which can come from damn near anywhere... transformers in the room, light switch dimmers, machinery in the neighborhood [especially if there are large printing presses... they're a nightmare].

Do you live by a river or a lake? Those can act as incredible 'ground planes' for random radio frequency signals [though if you're not hearing a radio station or TV station, chances are good that its not RFI related, only "stray field" related... which is none the less a nightmare [at times, not all the time].

Have you tried the unit in different slots in the frame? Have you tried moving the frame to another part of the room? Do you have the ability to buy or make "ground lift barrel connectors" [which is a male XLR on one side, and a female XLR on the other side, that has no attachment from pin 1 to pin 1... which lifts the ground... hence why its called a "ground lift barrel connector"].

Both the BAE and the Daking have been around for decades... chances are great that neither unit is the problem, and that the problem exists in the larger facility [which means it will absolutely be in your best interest to find the SOURCE of the interference and kill it at the source, rather than sending back units].

As always, YMMV

Peace
Old 15th April 2019
  #3
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Quote:
Originally Posted by Fletcher View Post
It depends on the hum... is it a straight hum at your local voltage? Under your name it say you're from Taipei City, if I remember correctly, Taiwan is all 110v from the wall. Is the hum you're hearing at 110Hz, 220Hz, 330Hz?... or is it more of a higher frequency "buzz" [there are a LOT of different hums... sometimes its just easier to teach the damn thing the words ].

If its a grounding thing [as in two or more paths to ground that have potential energy between them], then you just have to hunt down the grounding thing [there are only 6 combinations to try lifting one or two of... audio input, audio output, electricity from the wall].

If its a higher frequency "buzz" that opens up a whole new can of worms... as it could very well be "air born"... as in "stray field" related... which can come from damn near anywhere... transformers in the room, light switch dimmers, machinery in the neighborhood [especially if there are large printing presses... they're a nightmare].

Do you live by a river or a lake? Those can act as incredible 'ground planes' for random radio frequency signals [though if you're not hearing a radio station or TV station, chances are good that its not RFI related, only "stray field" related... which is none the less a nightmare [at times, not all the time].

Have you tried the unit in different slots in the frame? Have you tried moving the frame to another part of the room? Do you have the ability to buy or make "ground lift barrel connectors" [which is a male XLR on one side, and a female XLR on the other side, that has no attachment from pin 1 to pin 1... which lifts the ground... hence why its called a "ground lift barrel connector"].

Both the BAE and the Daking have been around for decades... chances are great that neither unit is the problem, and that the problem exists in the larger facility [which means it will absolutely be in your best interest to find the SOURCE of the interference and kill it at the source, rather than sending back units].

As always, YMMV

Peace
It is a PITA fo sure.

I’m actually back in the US. I’ve just neglected to update my gearslutz profile.

I have tried the rack in a different outlet but no dice. Haven’t moved the rack to another side of the room yet. I think the hum is in the lower frequencies. I looked at the logic eq plug and it looked like the hum was around 40/50 hz but that was just according to the visual of the plug.

No lakes or tv/radio towers...I don’t think. Do you have a thread or any links to help my adventure into exploring the grounding possibilities?
I’m sure that’s not easy to explain. I also have no experience soldering and dabbling in electronics.

In case it helps, I have heritage elite pre/eq’s that don’t have the hum.

Thanks again, Fletcher
Old 15th April 2019
  #4
member no 666
 
Fletcher's Avatar
110vac is 110vac... doesn't matter where its made Taipei or Jackson, Mississippi... so long as you don't have any hash on the line [usually caused by local industry], its all the same.

If the hum is in the lower frequencies, then you're going to want to try lifting the ground on the audio input or output [trial and error style] with the round pin on the Edison [wall AC] connector either tied or lifted [there are six combinations... list them, and log them so you don't end up chasing your tail around in circles].

This is a link for a $1.87 barrel connector... you open it up, clip the wire that runs from Pin one to Pin one and you now have a "ground lift". XLR Male/Male barrel Coupler | Shop Quality AV Cables, Connectors, and Accessories You might want to get a few of them so you can do things like make "polarity reverse" connectors [Pin 2 on one end goes to Pin 3 on the other and vice versa... comes in VERY handy with some older microphones]... you may have to learn how to solder... but that's never a bad skill to have.

This is a link for an 80¢ AC ground lift... Eaton 419GY AC 3-Prong Ground Lift Grounding Plug Adapter with Lug

If those don't work, I have a Sescom "IL-19 Extreme Hum Fighter" that was a leftover from another project... PM me your address and I'll mail it to you. Will it work in your applications? DAMIFIKNOW

Best of luck with it

Peace
Old 15th April 2019
  #5
Lives for gear
 

Thanks, Fletcher.

I’ll check that out this week.

On another note, I think I received the wrong PSU from Vintage King. I looked on BAE website and their racks come with a 1 XLR PSU. Mine is the 2 XLR PSU for single and duall 19” rackmount 312 I think. That would make it 1.6 amp to 2 XLR, but it should be 2.1 amp on 1 XLR. Pics below

I hope that’s the problem. I’ve contacted them. If you know whether or not that could be the culprit, pls let me know.

Thanks again
Attached Thumbnails
500 rack hum testing-a453e53f-a76f-4336-9973-591717a2dc97.jpg   500 rack hum testing-16197879-28a0-4bbb-b2ee-f6dd7d4a59f6.jpg  
Old 16th April 2019
  #6
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Reached out to BAE and VK. Power supply is probably correct but an older model. VK suggested taking out module and seeing what happens. Hum actually goes away if the Daking is out of it and xlr connection are kept in.

It may be the Daking. Have another module on the way to test. If I get a hum with this different one, I’ll check out the outlets like Fletcher suggested.

On another note, I’m probably the most annoying customer.

Old 16th April 2019
  #7
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nosebleedaudio's Avatar
 

Where is the power supply located? On top of unit? On floor?
Also, is this a new place you are using? If so it could be a AC outlet problem..
How are you monitoring this? Console?
One of the most useful cables I have is a XLRF to 1/4" jack, so I can plug straight into a mic pre ect output and straight to phones...

Last edited by nosebleedaudio; 16th April 2019 at 03:22 PM..
Old 16th April 2019
  #8
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Quote:
Originally Posted by nosebleedaudio View Post
Where is the power supply located? On top of unit? On floor?
Also, is this a new place you are using? If so it could be a AC outlet problem..
I’ve put the power supply on both table top and the floor in various areas. Never on the rack itself. That doesn’t seem like a good place. The Daking always generates the same level and frequency of hum.

Not sure what you mean by “new place”, but the house is old although recently renovated. No other equipment generates this hum. When the BAE is unloaded, the hum is absent.

Hope I can get to the bottom of this with out electrical work. I really hopes it’s just gear related
Old 16th April 2019
  #9
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Quote:
Originally Posted by nosebleedaudio View Post
Where is the power supply located? On top of unit? On floor?
Also, is this a new place you are using? If so it could be a AC outlet problem..
How are you monitoring this? Console?
One of the most useful cables I have is a XLRF to 1/4" jack, so I can plug straight into a mic pre ect output and straight to phones...
Monitoring through phones on my Apollo x8. Rack goes right into it line level.
Old 16th April 2019
  #10
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nosebleedaudio's Avatar
 

Quote:
Originally Posted by Ox Han View Post
I’ve put the power supply on both table top and the floor in various areas. Never on the rack itself. That doesn’t seem like a good place. The Daking always generates the same level and frequency of hum.

Not sure what you mean by “new place”, but the house is old although recently renovated. No other equipment generates this hum. When the BAE is unloaded, the hum is absent.

Hope I can get to the bottom of this with out electrical work. I really hopes it’s just gear related
New place, I should have said New location..
Old 17th April 2019
  #11
Gear Addict
 
withintheflux's Avatar
...also having a hum issue coming out of a Retro Doublewide via my brand new BAE 11 space rack. It doesn't happen via the much cheaper Lindell 610 rack. Following the thread.
Old 20th April 2019
  #12
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Quote:
Originally Posted by withintheflux View Post
...also having a hum issue coming out of a Retro Doublewide via my brand new BAE 11 space rack. It doesn't happen via the much cheaper Lindell 610 rack. Following the thread.
That’s weird. I’m sure someone could chime in as to why the cheaper one works. Maybe keep the cheap one and return the BAE. Or, if you needed more space, buy a larger, cheap 500 rack.

Here’s the best I can offer from my experience and the tech support at VK. Cheaper supplies usually use a “switching” power supply. I couldn’t tell you what that means, but most switching units are well filtered and power comes out really clean.

Expensive racks, like the BAE, have linear power supplies. Again, couldn’t tell you what that means, but better and more stable supplies.

Sometimes both types just don’t play nice with a particular unit I guess. My problem with the noise is that it increases with gain and I’m told that is not a ground loop issue. The 73jr I have temporarily is better, but still has that noise. Much less though and useable. However, it’s not mine and I only own the Daking.

Not sure how to go about my plan to go mostly 500 series or if I should go about with Fletchers method. I might try a cheaper rack or and API 5b and see if that’s the same. The lack of experience and the amount of time I’d spend using Fletchers method would leave me really disappointed if I still had that issue.

Good luck with your situation.
Old 20th April 2019
  #13
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nosebleedaudio's Avatar
 

Quote:
Originally Posted by withintheflux View Post
...also having a hum issue coming out of a Retro Doublewide via my brand new BAE 11 space rack. It doesn't happen via the much cheaper Lindell 610 rack. Following the thread.
How many slots are filled?
Or does it hum with ONLY the Retro installed?
Old 20th April 2019
  #14
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withintheflux's Avatar
Quote:
Originally Posted by nosebleedaudio View Post
How many slots are filled?
Or does it hum with ONLY the Retro installed?

10 out of 11 were filled. I haven't tried it with the Doublewide only but I have tried it after removing 4 of the adjacent modules...same noise.

Actually been chatting with Phil at retro who is going to take a look at the doublewide to make sure its working correctly. If so, maybe the BAE doesn't play nice with it. we'll see.

These types of scenarios are definitely arguments in favor of 19" gear.. where power supplies are designed for the device alone.
Blake
Old 20th April 2019
  #15
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nosebleedaudio's Avatar
 

Quote:
Originally Posted by withintheflux View Post
10 out of 11 were filled. I haven't tried it with the Doublewide only but I have tried it after removing 4 of the adjacent modules...same noise.

Actually been chatting with Phil at retro who is going to take a look at the doublewide to make sure its working correctly. If so, maybe the BAE doesn't play nice with it. we'll see.

These types of scenarios are definitely arguments in favor of 19" gear.. where power supplies are designed for the device alone.
Blake
I would try it with IT alone JUST to see...
I did notice that the doublewide does not use both edge connectors for power, not knowing the basics of Both BAE & the Retro makes it impossible to know what IS the problem...Interesting...
IM curious if the BAE has current limiting on the edge connectors..

There some aspects of the 500 series that is NOT ideal...IMHO
Some treat it like it was a like a console which has several power supply's to drive all the different circuits, +-18V, +24V, +5V for example...
But blaming the SET IN STONE 500 series is NOT the answer, IMHO...
I LOVE the 500 series for most gear...

I do agree about power supply's, If I built a tube based unit it would have the typical 12V for the heaters, a HV section 150V and higher for plate voltage as a minimum...(+5V for LED's ect also) So it would be based on a transformer with at least two different winding's, two different regulated or filtered outputs...
Old 3rd May 2019
  #16
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Just an update.

I returned the BAE and VK were as helpful as they could be I think. I’m out of town at the moment, but will get a different rack and see what happens.

Will go for either the API 6B or bento 6s
Thanks for everyone’s input and VK/BAE support.
Old 19th May 2019
  #17
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I was curious what difference another rack would make and wanted a cheap, yet reliable, rack that could be a control for the problematic “hum” mentioned above. I went with the OST 4 space for a temporary solution at the cheapest price.

Result: no hum. Dead silent. Both the Daking and the 73jr.

So, it turned out it was the power supply in the BAE. Whether it was faulty or just didn’t work out in my space I’ll never know. But I’m relieved it wasn’t the wiring or my space.

Thanks, Fletcher for your suggestions though I’m glad I didn’t have to implement them.
Old 19th May 2019
  #18
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toledo3's Avatar
 

When you have something like that happen it can be because of multiple ground potentials, and lifting ground can fix it.

But if it’s because there is a problem with ground connectivity in the first place, then ground lift will not fix it.

You got rid of the PSU already, but in a similar scenario I would figure out where the grounding inside the 500 series module is expecting to resolve, then follow the connection into the PSU, and down the path, making sure there are no problems along the way. Can even be something a stupid as one of the pins not making solid contact.

The other thing that can happen is that the transformer involved in the PSU might be causing some hum to pollute the signal of a given module. Sometimes just reorganizing the rack so that a susceptible module is physically further from the PSU power transformer can be a good idea. PSUs that use toroidal transformers can help too.
Old 20th May 2019
  #19
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Quote:
Originally Posted by toledo3 View Post
When you have something like that happen it can be because of multiple ground potentials, and lifting ground can fix it.

But if it’s because there is a problem with ground connectivity in the first place, then ground lift will not fix it.

You got rid of the PSU already, but in a similar scenario I would figure out where the grounding inside the 500 series module is expecting to resolve, then follow the connection into the PSU, and down the path, making sure there are no problems along the way. Can even be something a stupid as one of the pins not making solid contact.

The other thing that can happen is that the transformer involved in the PSU might be causing some hum to pollute the signal of a given module. Sometimes just reorganizing the rack so that a susceptible module is physically further from the PSU power transformer can be a good idea. PSUs that use toroidal transformers can help too.
But the new rack has zero hum. Wouldn’t that eliminate the possibility of a ground problem in my space? Honestly, I thought it would but I know next to nothing about this level of electricity and engineering.

I did try the Daking in nearly every slot and in just about every possible place in the room. The tech at VK also said he suspected a faulty power supply b/c of the frequency of the hum and that it increased with gain. He said that last point especially eliminated it being a ground hum.

All I know is that the problem is gone and all I did was get a different rack and power supply. I’m very glad I didn’t have to do wiring or install special material in my outlets
Old 20th May 2019
  #20
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toledo3's Avatar
 

Quote:
Originally Posted by Ox Han View Post
But the new rack has zero hum. Wouldn’t that eliminate the possibility of a ground problem in my space? Honestly, I thought it would but I know next to nothing about this level of electricity and engineering.

I did try the Daking in nearly every slot and in just about every possible place in the room. The tech at VK also said he suspected a faulty power supply b/c of the frequency of the hum and that it increased with gain. He said that last point especially eliminated it being a ground hum.

All I know is that the problem is gone and all I did was get a different rack and power supply. I’m very glad I didn’t have to do wiring or install special material in my outlets
Yeah I agree that it eliminates the likelihood of it being ground hum at your place, as far as the wall power goes.

It doesn’t necessarily eliminate the possibility of all of the other points. If the module wasn’t able to find ground from the PSU it was connected to, then I would think the hum *would* increase with gain on the module. That doesn’t mean your place’s grounding is messed up, but it could mean something “wrong” with the ground connection between the module and the PSU. What, not sure because it’s not in front of me.

But that’s not your worry now thankfully. Good luck and glad it got resolved.
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