Zen V4 - Page 2

Stabist · 9th February 2003, 09:26 PM

The hum is mechanical - if I put my ear on the top of chassis - you can hear it quite easely ...

The same hum can be also heard on speakers - just that it is even more loud.
BUT - if one interconect is pulled out - almost nothing - speakers are almost silent ...
So - I guess there is a ground problem - there are few things I'll have to inspect - the first one is - there is no 22kR resistor yet .. Then - mr. Nelson allready sugested to ground RCA inputs ..
But - as said - there hasn't been enough time to play with ... And also momentarily the osciloscope is dead

So ...

The thing is - the chassis is very compact - and it gets quite crowdy inside - so - Kirc and I must have enough time to try some solutions - it shall be a couple hours job ...

till · 9th February 2003, 09:40 PM

OK. In my opinion the only consequent thing you can do against the mechanuical noise i described above.

At the speaker, without a long antenna cable at the input, with normal speakers, you should hear nothing. Zen V2 i hear some hum. Zen V4 - nothing.

Nelson Pass · 9th February 2003, 10:31 PM

Toroids are very susceptible to crap on the AC line,
particularly DC imposed by lamp dimmer circuits and
such.

Try putting a couple of 10,000 uF caps back to back
(series) on the AC line to the primary to block DC and
see if that doesn't help.

Stabist · 9th February 2003, 10:46 PM

mr. Nelson I agree - if there is DC component - trannie can get "overmagnetized" - don't know the expression - I mean - B(H) charachteristic and stuff conected with all that ...

Series of 10.000uf caps between AC power cord and trannie if I understood you right?? Hmm - what about voltage of such capacitors?? 230V is quite high - I'm not sure if there are some 230V/10.000uF caps ... - I mean - am I missing something here or ... ?!?

till · 9th February 2003, 11:03 PM

10000uF / 63V 4 times in series => 2500uF / 250V ??

Stabist · 9th February 2003, 11:15 PM

Quote:

Originally posted by till
10000uF / 63V 4 times in series => 2500uF / 250V ??

Hmm - it can be clearly seen that it has been a long long day - and that I should allready be in bed for at least 2 hours ...
I've mixed up serial and paralel ....

... Silly me ...

Oh ... I feel so

I feel soooooooo stupid ...

miguel2 · 10th February 2003, 08:55 AM

I tried this weekend a DC trap with a 3300uF/25V cap and 4 diodes as in the figure. I noted that when I turned it up it was silent but then the transformer started to hum again.

I am thinking in putting it in a vacuum oven

to get the air trapped inside and then bake it. Does anyone knows the baking temperature for these guys?

Per Nielsen · 10th February 2003, 09:09 AM

I really dont under stand why you have theese kind of problems, its just a question about a big enough trafo and enough capitance, then you will not have theese noise/hum problems
Please correct me if im wrong!!

miguel2 · 10th February 2003, 09:20 AM

I am using a 800VA toroidal.
Caps are 20000uF per channel.

I do believe my transformer is a bit old but toroids are said to be lifetime guaranteed

.

Per Nielsen · 10th February 2003, 09:50 AM

Are you sure it is your transformer that makes the hum?If it is I would not believe in that gaurantee,it could also be the grounding problem or even worse dried out caps!

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9th February 2003, 09:26 PM	#11
Stabist diyAudio Member Join Date: Sep 2002 Location: Slovenia	The hum is mechanical - if I put my ear on the top of chassis - you can hear it quite easely ... The same hum can be also heard on speakers - just that it is even more loud. BUT - if one interconect is pulled out - almost nothing - speakers are almost silent ... So - I guess there is a ground problem - there are few things I'll have to inspect - the first one is - there is no 22kR resistor yet .. Then - mr. Nelson allready sugested to ground RCA inputs .. But - as said - there hasn't been enough time to play with ... And also momentarily the osciloscope is dead So ... The thing is - the chassis is very compact - and it gets quite crowdy inside - so - Kirc and I must have enough time to try some solutions - it shall be a couple hours job ...

9th February 2003, 09:40 PM	#12
till Banned Join Date: Apr 2002 Location: Germany, Clausthal	OK. In my opinion the only consequent thing you can do against the mechanuical noise i described above. At the speaker, without a long antenna cable at the input, with normal speakers, you should hear nothing. Zen V2 i hear some hum. Zen V4 - nothing.

9th February 2003, 10:31 PM	#13
Nelson Pass The one and only Join Date: Mar 2001	Toroids are very susceptible to crap on the AC line, particularly DC imposed by lamp dimmer circuits and such. Try putting a couple of 10,000 uF caps back to back (series) on the AC line to the primary to block DC and see if that doesn't help.

9th February 2003, 10:46 PM	#14
Stabist diyAudio Member Join Date: Sep 2002 Location: Slovenia	mr. Nelson I agree - if there is DC component - trannie can get "overmagnetized" - don't know the expression - I mean - B(H) charachteristic and stuff conected with all that ... Series of 10.000uf caps between AC power cord and trannie if I understood you right?? Hmm - what about voltage of such capacitors?? 230V is quite high - I'm not sure if there are some 230V/10.000uF caps ... - I mean - am I missing something here or ... ?!?

9th February 2003, 11:03 PM	#15
till Banned Join Date: Apr 2002 Location: Germany, Clausthal	10000uF / 63V 4 times in series => 2500uF / 250V ??

10th February 2003, 09:09 AM	#18
Per Nielsen diyAudio Member Join Date: Feb 2003 Location: Aalborg, Denmark	I really dont under stand why you have theese kind of problems, its just a question about a big enough trafo and enough capitance, then you will not have theese noise/hum problems Please correct me if im wrong!!

10th February 2003, 09:20 AM	#19
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I am using a 800VA toroidal. Caps are 20000uF per channel. I do believe my transformer is a bit old but toroids are said to be lifetime guaranteed .

10th February 2003, 09:50 AM	#20
Per Nielsen diyAudio Member Join Date: Feb 2003 Location: Aalborg, Denmark	Are you sure it is your transformer that makes the hum?If it is I would not believe in that gaurantee,it could also be the grounding problem or even worse dried out caps!