Moreplay - Hum in the input-chanel with phono preamp, left chanel cracks[solved]

[mail@jenspussel.de]

Hi everybody.

I finished my Moreplay some days ago and I am absolutely in love with it. but the romantic part is over now, and I need some practical help with 2, maybe 3 issues. I don´t know if they all belong to the Moreplay, or if they are problems in the rest of the chain.

I didn´t have problems with my system before I switched the preamps to the moreplay.

1. I turn my system on and I have a general light hum in the system, that is volume independent. Its not terrible, but I hear it from my seat.
2. If I use my Denfrips Ares/Limetree Bridge as a source, there is just this light hum, that doesn´t get louder with more volume. If I connect my Ifi zen phone/project evo carbon debut, there is a very loud hum and it gets even louder with rising volume. If I connect a ground wire frome the Ifi zen phono to the Moreplay, the loud hum without any volume goes away, but if I turn some volume up, a big hum is coming.
3. The left chanel starts cracking after prox. 5 minutes, its not super loud, but you can here it and it gets louder with rising volume. I changed the input-chanels, the output-chanels and the tubes, but the cracking remains on the left side. I checked all soldering and it seems ok, but I will look again.

I checked the forum for similar problems and there were similar problems, but they didn´t help to solve my problems.

It would be great if somebody would have ideas. I read something about shorting jacks, and I will figure out how to make them...

thanks in advance.
cheers
Jens

 

[Doc B]

You most likely need to reflow your solder joints. You can't tell if they are good just by looking at them, as the continuity problem can be beneath the surface of the solder.  Start with ground connections since you have a hum issue and then go over the left channel tube socket connections to try to resolve the crackle in that channel. Just heat the solder joint to reflow it, and maybe add a TINY bit more solder if necessary.

 

[mail@jenspussel.de]

Thank you Doctor B for your fast reply!
I have reheated all of the soldering positions, except the switch, I didn't messure it after, because I didn't change anything and connected it to the poweramp. There was a little puff on the left speaker (where the cracks were before) and than the left tube stopped glowing. But the Tube is not broken, I put it in the other socket and it lit up. I measured everything now and there are some strange things happening with the numbers. So, on Terminal 4, where it should be 620 Ohm, there is now -9, on Terminal 9, where it should be 10kOhm, there was noting, on 14 where it should be 620Ohm, there is 90 Ohm now. Terminal 25 is  - 40 ohm now, Terminal 31 is - 80 now. Tube Terminal: A1 is 90 ohm,  A2 is -14 Ohm,  A7 is -14, A8 is 90 ohm. B1 is -9 Ohm, B2 is -14 Ohm, B7 is -14 Ohm, B8 is changing around 10 Ohm...

I have unfortunately no experience with electronic stuff. I am very grateful for any help
Tank you

 

[Paul Birkeland]

There was a little puff on the left speaker (where the cracks were before) and than the left tube stopped glowing.

That is very much a soldering problem. If you post a picture of the inside of your build, I can draw some arrows to the joints you need to resolder to get that socket back up and running.

 

[mail@jenspussel.de]

Hi Paul

thank you for your kind offer! I really appreciate it! I thought I can avoid posting a photograph of my soldering, because I am not experienced at all, but here we go...
I do love the sound of the Moreplay and I realized how much, when I connected my old one back into the system.

regards
Jens

 

[Paul Birkeland]

The H terminals and the 3 ohm resistors make the tubes glow.  There's something not connected or not properly positioned there.  The shielded twisted pair wiring should not be up against the terminal strips, but rather it should come off the back and as much of the wiring should be pushed against the chassis as possible.

You also have a black wire that's just floating in the air not connected to anything.

 

[mail@jenspussel.de]

Hi Paul

you were absolutly right with the H-terminals! the red wire on H3 was just cut off for some reasons? I replaced it because when I dismanteled it I cut to deep with the cutterknife. The black wire is connected, it just looks disconnected. And the twisted wire doesn´t touch the terminal, its just a bit long I guess and not very good laid. But both tubes are glowing and the music plays just as beautiful as before!  I still have the grounding problem, that I mentioned in my first post. But for now I am very happy and grateful for your and Dr. B´s help!!!

thanks
Jens

 

[Karl5150]

I didn't see if this had been mentioned earlier in the thread, or know if it is related, but the cap (?) to ground on the inboard, left ch RCA input looks damaged.
Karl

 

[mail@jenspussel.de]

Hey Karl

wow, I didn´t even see that, but you are also absolutely right! Could this (broken) resistor cause the hum? You mean the little yello one on the RCA´s that has a crack? should I just replace it?

Thanks
Jens

 

[Karl5150]

They looked kind of like the yellow ceramic caps from the Eros, but yes that is what I was referring to. Again I don't know if that is a possible cause, Doc or the Pauls would know. BTW, the top plate and tranny bell finish/color look great.
Karl

 

[Paul Birkeland]

Those little yellow caps are a preventative component and even if that one was completely shorted, it would only potentially cause some noise problems on that specific input.

 

[mail@jenspussel.de]

Thank you for your hints and ideas and of cause for your feedback about the finish! I will try some thing to get rid of the hum and I will research about the ifi zen phono if other ppl have a similar problem. have a lovly sunday!

Jens

 

[mail@jenspussel.de]

hello again,

I couldn´t find anything about the Ifi Zen phonopreamp in the internet that could help, but I found out that only if I connect the Denafrips to the Moreplay via rca there is no hum. if I connect the Wiim mini, with 3,5 jack into the Wiim and rca into the Moreplay there is hum. the same with the Ifi Zen phonopreamp also rca. I always tried it with all 3 imputs, just the denafrips was silient. the moment I connect the rca between the Moreplay and the denafrips the hum desappears. If I don´t connect anything to the Moreplay there is hum in all of the 3 inputchanels. its the same hum that the Ifi Zen or the Wiim mini create, when they are connected.

And unfortunately my left chanel ist still cracking from time to time.

I am grateful for any ideas.

thanks
Jens

 

[Paul Birkeland]

Have you connected the black wire that's just floating around and not going anywhere in your build?

 

[mail@jenspussel.de]

Hi Paul

if you mean the black cable that is going over the left tube socket, that is actually connected. It is just a little to long and for that reason it looks disconnected.

 

[Paul Birkeland]

When I have run into the problem you're describing, frequently the source of the issue is that earth ground, the chassis, and audio ground are in a state of relative disagreement with each other.  I just debugged an amp with this same problem the other day, and I had to scrape off some coating on a panel that was preventing the audio ground and chassis from connecting properly.  In your preamp, I would look carefully at the tinned buss wire around the IEC power entry module and be sure all your hardware is tight.  When you are connecting the Denafrips, it is temporarily restoring whatever is missing.

 

[Deluk]

Where is that black wire connected to? Its counterpart on the other valve looks to go to the adjacent tag strip and the "spare" wire doesn't look to go anywhere near the left one. Photo?

 

[mail@jenspussel.de]

Hi Everybody!

Many Thanks to everybody and especially to those who helped me figuring out the problems!!! It is solved and you where again
absolutely right, I soldered the black cable to the tubesocket for some reasons??? I changed it and now there is no hum at all and it sounds
absolutely devine!

Thank to everybody!
Great Forum!

Jens