PassAleph 3 power amp with hum noise, please help

[Pass lover]

Hi every body,

Could you please let me know how to deal with the hum noise which com from the speaker driven by PassAleph 3 power amp?

Even though the amp was warm enough, I still heard the hum noise from the RIGHT speaker. the left one also made a hum noise but rather smaller (when you put your ear very close to it).

Of course, when the amp is cool (just turned on) the hum noise from both channel is very clear ( special the right channel)

Especially, there is absolutely no noise from the PassAleph3 even though you put your ear very near to it.

I was wondering if it is the nature of the amp. If not, please let me know how to deal with it.



Any body who are using the PassAleph3, please let me know.

My speaker is B&W P6 which did not make any hum noise when being connected to Bryston power amp

Please

I am looking forward to your reply

Thank you inadvance for your time and reading

 

[Nelson Pass]

Often hum is due to ground loops. I suggest you devise a
pair of RCA (male) shorting plugs (hot to ground), put them
into the inputs, and see what kind of noise you get. In this
way you can eliminate the possibility of external connections
creating ground loops and see what the amp does by itself.

 

[Pass lover]

Thank you very much Nelson Pass

But I could not make any head or tail of what you suggest. Could you please show me how to do in detail.

"hot to ground" means that I will solder possitive polar of the RCA ( often Male one) to a seperate wire, then connect the wire to where? where is the ground in this case

Please

 

[Zen Mod]

Thank you very much Nelson Pass

But I could not make any head or tail of what you suggest. Could you please show me how to do in detail.

"hot to ground" means that I will solder possitive polar of the RCA ( often Male one) to a seperate wire, then connect the wire to where? where is the ground in this case

Please

take two RCA naked jacks
solder (or connect with clips) live (center) and ground (outer) on each of them;
plug them both in L and R of your Aleph , so-in that way you GROUNDED or SHORTED (not yelling ) inputs.
power up aleph

if you still have hum or whatever from your spks,then Aleph is broken and you can send that lousy amp to me for proper disposal

 

[steenoe]

But I could not make any head or tail of what you suggest.

Mastertech, Lineup, Pass lover, isnt that the same?? How could I know??? Dont worry, I have THE crystalball.
And I am on the lookout

Steen
Dont even try to **** with me, you will be doomed

 

[Zen Mod]

Mastertech, Lineup, Pass lover, isnt that the same?? How could I know??? Dont worry, I have THE crystalball.
And I am on the lookout

Steen
Dont even try to **** with me, you will be doomed

 

[MEGA_amp]

Well he does spell correctly and uses punctuation, so it couldn’t be good ole george.

 

[Babowana]

Mastertech, Lineup, Pass lover, isnt that the same??

Is it?

 

[Pass lover]

Thank you very much ZenMod


There are 4 RCA connectors: 2 RCA plugged in the pre-amp, 2 RCA plugged in the power-amp

All I have to do is: to take 2 RCA (from the power amp) then short them: solder the live(center) to the ground(outer). Is it true?

Final question, there is only hum noise from the right channel, so I just ground only one right RCA interconnect?

A bit stupid, but I would like to make sure and clear before doing. I think there is no harm to ask, isnt it?

I am looking forward to your reply

 

[Netlist]

Mastertech, Lineup, Pass lover, isnt that the same??

No.

/Hugo

 

[Netlist]

Imagine a wire between the two white clips.
Don't pay attention to the resistor in the picture.
Connect as shown.
Now your one input is shorted to ground.
Short the humming channel, then the other, then both and listen if you hear any difference.

/Hugo

 

[Nelson Pass]

Final question, there is only hum noise from the right channel, so I just ground only one right RCA interconnect?

Yes, you can do this one channel at a time. The point is to
evaluate the noise not connected to a source. At the same time,
an open input will pick up stray noise, and so is shorted to ground
to avoid that.

 

[mercc]

Hi,

I have the same problem, lots of hum from right channel and smaller amount from left channel. When I short rca inputs, very small portion of hum disappears, I would say the grainy part but big smooth remaining part of hum stays. So which components have to be replaced to lower the hum?
Also I read that inner noise of the amplifier can be lowered by lowering the output gain by 6 db, how can this be done?

Thanks

 

[mercc]

From audio analyzer output, the hum seems to have peak mostly at 100 Hz, lower peaks are around 200, 150, 300 and 50 Hz.

 

[mercc]

After shorting rca inputs, the hum peaks seems to be (in descending order): little over 150Hz, then 250, 100, 50 and 550 Hz.

 

[mercc]

After removing cables and shorting rca inputs with short wire has the hum peak at 100Hz and lower peak at 200 Hz. Measurement of zener diodes with digital multimeter show values 780 for left and 782 (mv?) for right channel. So maybe replacing the diodes will lower the hum.

 

[cfcubed]

If the noise came about w/no other changes to setup, and is confirmed not in source or due to faulty cable, I'd be inclined to think PS cap. Especially if the caps are 10/15 yrs older or more, live in a hot box and rated 85 deg.

Just my thoughts as a place to start if thinking component failure.
But others that know far than I have spoken & I'm speaking from quite limited experience.

Edit: And if its a design that has a series of large power supply caps in parallel per rail, it might be easy to see if one is faulty... Possibly pull one at a time, test for hum, then replace it & pull another one.
Not sure if that's a sanctioned form of testing, but...
In a NAD w/this problem I was able to confirm it was indeed PS caps by pulling the pair & replacing with a set w/equal (or higher) voltage rating. IIRC, the test replacement caps were only 1000uf, where origs where 4700uf, but the test was good enough to confirm them the culprit.

 

[mercc]

Thank you for your response. Can you tell me why there is more hum in the right channel? Somewhere i read that its design property of Aleph, but the wiring seems to be symmetrical for both channels. And capacitors are likey to wear out evenly for both channels in time.

 

[cfcubed]

Thank you for your response. Can you tell me why there is more hum in the right channel?

No, I know nothing about this design in particular. But if the design has a PS common to both channels, this would work against the PS cap at fault idea.

And capacitors are likey to wear out evenly for both channels in time. [/B]

I'd be surprised if this were the case. Of the 1000s of hours the caps are rated for, having 2 or more go in the same week would not seem likely to me. BUT if I found any caps at fault in a section I'd replace them all of course.

Although it seems an idea that's easy to try, if problem is only in 1 channel & design does not have fully independent PSs/channel, perhaps not the thing to try.