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SUPPORT FORUMS FOR ZKITS >> ZKIT 1 Support forum >> ZKIT1 Hum
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Message started by Mike B on 06/19/13 at 22:44:38

Title: ZKIT1 Hum
Post by Mike B on 06/19/13 at 22:44:38

Just finished the Zkit1 and it has a 5.5mv hum. I isolated it to the amp, took the input tube out and the hum is gone. Any help with this problem will be appreciated. The amp sounds wonderful but I would like to get this hum below 3mv.

Mike B

Title: Re: ZKIT1 Hum
Post by Lon on 06/19/13 at 23:23:44

Believe me, I am far from an expert, but. . .have you tried another input tube?

Title: Re: ZKIT1 Hum
Post by Mike B on 06/20/13 at 03:18:25

Thanks for the reply, Lon. Yes, I did try serveral input tubes, and also rectifier tubes. Maybe Steve will see this post and give me a suggestion.

Mike B

Title: Re: ZKIT1 Hum
Post by dank on 06/20/13 at 12:14:15

I think the Zkit board has been redone to correct some of the problems found and fixed tin the "Hum Problem" thread:
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1257041114
but you should read through that.

I believe the "Virtual CT for Edcor Heater Wires - WOW!" thread is still producing results:
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1352929896

good luck

Dan

Title: Re: ZKIT1 Hum
Post by Lon on 06/20/13 at 13:27:05

Well Mike, good that you tried some other tubes. I have to say that most of the time I've had hum issues with a Decware component it's been a tube that was responsible.

Title: Re: ZKIT1 Hum
Post by mboxler on 06/20/13 at 14:39:05

Hey Mike

I assume you mean you replaced the output tubes, or did you go with tube rectification instead of the diodes on the board?

I know pictures are a pain, but perhaps one of us can see something.

Mike

Title: Re: ZKIT1 Hum
Post by Mike B on 06/20/13 at 22:29:37

Mike, I replaced the input tube with new ones, no change. I also decided to use tube rectification and tried changing rectifier tubes but there was no change. The hum is not there with the input tube removed.

I built and original zen amp, and there is no hum the AC voltage on the speaker outs is less than 2mv, so the 5.5mv I have now is bothersome.

Since the hum is equal on both side, I'm checking the circuitry around the input tube.

I'll try to post pictures later tonight.

Mike B