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EQUIPMENT FORUMS >> ZROCK2 >> ZROCK2 hum
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Message started by TK78 on 08/27/19 at 21:13:04

Title: ZROCK2 hum
Post by TK78 on 08/27/19 at 21:13:04

hey Decware folks! I just received my Zrock after a long wait and WOW is it awesome! I run ZU druid Mk V's with a First Watt J2, PArks audio puffin phono stage and Luminous Audio Aciom pass pre. I just never got the bass I wanted until I plugged in the Zrock yesterday. No way would I have thought my speakers were capable of the chest thumping but articulate bass I am now getting. The only issue I have is that I am getting a hum from the Zrock. My system is 100% dead quite especially with the passive pre...even with rolling on the volume, nothing changes, just dead quiet. When I turn the Zrock off standby a noticeable hum occurs. Can anyone shed some light on this? Is it fixable? Should I place the Zrock somewhere else in the chain? This is not a major deal...just something i'm not used to. I know tubes make noise.

Title: Re: ZROCK2 hum
Post by Lon on 08/27/19 at 21:22:22

Congrats on the ZROCK2 and it doesn't surprise me that it is delivering excellent bass.

As for the hum, I would try placing it physically somewhere else in the system (and getting it out of the path of power cords if possible). And it may be the tube as well, if you have another 12AU7 or equivalent roll that in and see what happens.

Title: Re: ZROCK2 hum
Post by TK78 on 08/27/19 at 22:55:31

Thanks! Yes, I am absolutely stunned by the amount of bass I am getting. It's fantastic! As for the hum, I placed it all over the chain but the other two positions don't seem to work as well as between the preamp and power amp. I will try switching out the tubes and see what happens.

Title: Re: ZROCK2 hum
Post by Rivieraranch on 08/28/19 at 02:20:12

What about using shielded interconnect cables?

Title: Re: ZROCK2 hum
Post by TK78 on 08/28/19 at 06:35:25

I’m pretty shielded... I run ZU missions.

Title: Re: ZROCK2 hum
Post by jslateiv on 08/28/19 at 12:56:56

Hook the ZR2 up directly to the amp without a source plugged into the ZR2. You will naturally get a little noise if the inputs are not shorted. This can help tell where the hum is coming from. Did the noise change? If there is less noise now, then there is most likely a ground loop occurring in the chain. I would start by lifting the ground leg (cheater plug) on either the ZR2 or the Phono. It appears the Pre is DC powered and only for remote. Should only have to lift the ground on one piece of equipment not both.

If the noise is still the same (Zr2-no input/amp) as the normal hook up scheme, then it is definitely the ZR2 and could be a tube or the unit itself or the power feeding it. Trying the above configuration will tell you real quick where the source of the problem is though (or at least help you narrow it down greatly).

Also, if you have some spare/blank rca connectors laying around you can make shorting plugs by taking a piece of wire and soldering it between the shield and center pin. Using these on the inputs keeps the 'open' circuit from picking up stray room/eqip. born electrical noise/interference by shorting all the noise to ground. If you want to really know how quiet the ZR2 is (or the tube in it) you need to short the inputs with the ZR2 hooked to the amp. Also, do this before the amp is turned on.. Hope this helps and doesn't cause further confusion.

Title: Re: ZROCK2 hum
Post by TK78 on 08/28/19 at 17:52:42

Thank you for that detailed response! So I did just run the Zrock to the amp and that's where the hum is. So it must be the Zrock? I can look at switching out the tube...I don't have another 12AU7 handy. I might be able to grab one locally somewhere around here today.

Title: Re: ZROCK2 hum
Post by jslateiv on 08/28/19 at 19:00:30

Try lifting the ground if you have a cheater plug laying around. If you don't than any hardware store or Lowes/HomeDepot will have them. I'm almost willing to bet when you lift the ground all goes quiet.

Title: Re: ZROCK2 hum
Post by TK78 on 08/28/19 at 20:45:10

I tried the cheater plug, not that. Actually the hum was quieter without the cheater plug. hmmmm. I have a buddy that has another 12AU7. I will try that in a little bit.

Title: Re: ZROCK2 hum
Post by TK78 on 08/28/19 at 21:38:03

Switched out the tube....still have the hum. :( Again, this has nothing to do when playing music so that's good. But as soon as the album end you can hear it. My system has always been 100% dead quiet so I am not quite sure what to make of this.

Title: Re: ZROCK2 hum
Post by Lon on 08/28/19 at 23:54:36

Well, keep playing it. I think I remember my first ZROCK2 having a hum at first that dissipated with a few weeks of use.

Title: Re: ZROCK2 hum
Post by pursuitofnow on 08/29/19 at 06:21:48

Have you tried calling Steve? I understand not wanting to send it back but after all the troubleshooting you've done, it may be faster at solving the issue.

Title: Re: ZROCK2 hum
Post by jslateiv on 08/29/19 at 17:11:24

Interesting to say the least. I'm running Zu's as well and at their efficiency I have always been able to hear any noise in the system if there is any. I will say that for all purposes my ZR2 is dead quiet expect for a little tube noise/hiss which is normal for any tube (to a degree). This is into a SE84 Anniv. Amp which does not have a sensitive input.

Do you have any other cables you can try running between the ZR2 and amp? Did you try lifting the ground on the amp as opposed to the ZR2? Just a thought all though I don't think it will matter based on what you are saying.

I certainly wouldn't hesitate to call Steve either and let him know the troubleshooting steps you have taken. It's certainly possible something internal 'moved' during shipping and that's causing the hum.

The only other thing I can think of would be with the amps sensitivity. If the amp is overly sensitive to input gain, then it will be more prone to amplifying any self noise coming from predeceasing gear. I have run into this problem before and it really comes down to incompatibility between certain pieces of gear due to their gain sensitivity. Generally this happens between pre's and amps... Hope that's not the case as the ZR2 is awesome but it could be..

Title: Re: ZROCK2 hum
Post by jslateiv on 09/17/19 at 14:39:14

Hey TK78, If you still watching this thread, I'd love to know if you talked to Steve and or figured out what the problem ended up being. Thanks!

Title: Re: ZROCK2 hum
Post by TK78 on 09/20/19 at 18:15:39

So there was some type of internal grounding issue that was causing the buzz or hum. As I said above it was quite dramatic and got much worse over a few days. I sent it back and Steve fixed it and it's pretty much dead quite right now. There other issue of it being a little too hot for my J2 I am still testing. No problems so far though.

Title: Re: ZROCK2 hum
Post by Archie on 09/20/19 at 19:08:32

Wow, that's great. Glad it's resolved. It's never fun but Steve definitely stands behind his work.

Title: Re: ZROCK2 hum
Post by jslateiv on 09/21/19 at 12:53:08

Great to hear. Steve def. takes care of his flock! Thanks for reporting back with the issue and fix. Best!