Hum with aleph P

rbe43164 · 13th September 2006, 05:54 PM

My aleph P1.7 is more or less finished and sound marvellous but I have a humm with this.

I use a attenuator boards made using relays and precision resistors in balanced mode and when I increase the volume the hum increase.

I use board from PCB design and dantimax attenuator.

I have connected 1 ground to each channel to the chassis from the main board of Aleph p1.7 and only one ground goes between the 1.7 to the board attenuator. I think that I can’t have a ground loop with this configuration.

Do you have any suggestion?

Best regard’s

rbe43164 · 13th September 2006, 05:57 PM

picture

rbe43164 · 13th September 2006, 06:07 PM

one more for the pleasure
Aleph 5 and aleph P1.7

Incredible couple.
aleph 5 4x47000uf with 500va, matched mosfet 0.001volt??? with fluke p189, all precision resistor 0.1% +matched.
All cases made by my self. I'm happy and pround but the humm is unacceptable

tze-hao yen · 14th September 2006, 01:38 AM

ok
i had the some problem in the past too but what i find out it that if you put 4 resistor on the output will divid the nois out may be you can try it say like 4x 4.7k will work put then in the out put please try it first

AndrewT · 15th September 2006, 08:39 AM

Hi,
why have you connected audio ground to safety earth?

Do you take orders for chassis panels?
Well done.

rbe43164 · 15th September 2006, 06:44 PM

ANDREW

I don't understand your question. Could you explain me more. What do you mean with safety earth? Where do you want I connect my ground audio?

Best regards.

AndrewT · 15th September 2006, 07:04 PM

Hi,
mains powered equipment with exposed conductive parts must have a safety earth. This safety earth connects the conductive parts back to the electrical distribution board.

A fault current to safety earth will blow the fuse and isolate the faulty equipment from the mains Live input.

If this is new to you, then give up building mains powered equipment until you have been trained to stop killing yourself.

rbe43164 · 15th September 2006, 08:54 PM

Andrew

Sorry for my bad english but I know what is a safety earth and for proof you I can always reply to you

You have not understand my question and it's normal because sometime I speek like a spanish cow.
Meanwhile I have finded a part of the problem.
I continue but I feel that i will have maybe some help from you.
Best regards.

wayne325 · 16th September 2006, 03:42 AM

hmmmmmmmmmmm............

wayne325 · 16th September 2006, 03:49 AM

OK OK enough joking around. Lets see. You have a lot of hum and
it gets louder when the pre volume is turned up.

Do you have any hum from the power amps alone with no input
connected? It should be very quiet even when you put your ear
right by the speaker cone. Or at least you should be able to hear
nothing if your ear is a foot away from the speaker cones.

If the hum is only when preamp connected, try to disconnect all inputs
to the preamp. Do you still have hum? If not, then there is a ground
loop between the pre and the source component. If there is hum with
the pre inputs disconnected, then there is a ground problem between
the pre and the power amp.

I had a similar thing... on my power amps I had the + and G connections
reversed. Not good. I'd say look for the same sort of thing. Either the
pre output has an error or the cable has an error (are they DIY cables??)
or the power amp input has an error in the connections. THey are
all balanced connections, no?

If they are balanced, it should be so quiet it's spooky. Don't give up
til you find your problem.

One more thing - you did separate your signal ground from chassis
ground with a thermistor as in the schematics didn't you?

W.

13th September 2006, 05:54 PM	#1
rbe43164 diyAudio Member Join Date: Nov 2004 Location: near bruxelles	Hum with aleph P My aleph P1.7 is more or less finished and sound marvellous but I have a humm with this. I use a attenuator boards made using relays and precision resistors in balanced mode and when I increase the volume the hum increase. I use board from PCB design and dantimax attenuator. I have connected 1 ground to each channel to the chassis from the main board of Aleph p1.7 and only one ground goes between the 1.7 to the board attenuator. I think that I can’t have a ground loop with this configuration. Do you have any suggestion? Best regard’s

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14th September 2006, 01:38 AM	#4
tze-hao yen diyAudio Member Join Date: Jul 2004 Location: brooklyn	ok i had the some problem in the past too but what i find out it that if you put 4 resistor on the output will divid the nois out may be you can try it say like 4x 4.7k will work put then in the out put please try it first

15th September 2006, 08:39 AM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, why have you connected audio ground to safety earth? Do you take orders for chassis panels? Well done.

15th September 2006, 06:44 PM	#6
rbe43164 diyAudio Member Join Date: Nov 2004 Location: near bruxelles	ANDREW I don't understand your question. Could you explain me more. What do you mean with safety earth? Where do you want I connect my ground audio? Best regards.

15th September 2006, 07:04 PM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, mains powered equipment with exposed conductive parts must have a safety earth. This safety earth connects the conductive parts back to the electrical distribution board. A fault current to safety earth will blow the fuse and isolate the faulty equipment from the mains Live input. If this is new to you, then give up building mains powered equipment until you have been trained to stop killing yourself.

15th September 2006, 08:54 PM	#8
rbe43164 diyAudio Member Join Date: Nov 2004 Location: near bruxelles	Andrew Sorry for my bad english but I know what is a safety earth and for proof you I can always reply to you You have not understand my question and it's normal because sometime I speek like a spanish cow. Meanwhile I have finded a part of the problem. I continue but I feel that i will have maybe some help from you. Best regards.

16th September 2006, 03:42 AM	#9
wayne325 diyAudio Member Join Date: Jun 2005 Location: Dallas, Texas	hmmmmmmmmmmm............

16th September 2006, 03:49 AM	#10
wayne325 diyAudio Member Join Date: Jun 2005 Location: Dallas, Texas	OK OK enough joking around. Lets see. You have a lot of hum and it gets louder when the pre volume is turned up. Do you have any hum from the power amps alone with no input connected? It should be very quiet even when you put your ear right by the speaker cone. Or at least you should be able to hear nothing if your ear is a foot away from the speaker cones. If the hum is only when preamp connected, try to disconnect all inputs to the preamp. Do you still have hum? If not, then there is a ground loop between the pre and the source component. If there is hum with the pre inputs disconnected, then there is a ground problem between the pre and the power amp. I had a similar thing... on my power amps I had the + and G connections reversed. Not good. I'd say look for the same sort of thing. Either the pre output has an error or the cable has an error (are they DIY cables??) or the power amp input has an error in the connections. THey are all balanced connections, no? If they are balanced, it should be so quiet it's spooky. Don't give up til you find your problem. One more thing - you did separate your signal ground from chassis ground with a thermistor as in the schematics didn't you? W.