Jensen or Mundorf coupling capacitors?

[decooney]

Originally Posted by timm

So... this guy was WRONG!!! haha.... So yes... I am still hovering around the phono stage... But, after the above.... long play time - probably on/off for 80 hrs... fuse blew.... and I found I was getting some low level hum in the speakers (midrange) only when the new phono tubes were in.... The ground has been lifted via a cheater ........ When I Remove phono tubes - hum seems like it has gone.... So, I am going to play like this for awhile... If it plays clean - no hum... no blown fuse .... then I will re-introduce the new phono tubes... If hum comes back - it seems like the issue is the phono stage itself - not the tubes that are connected to it....

Let me ask if anyone knows -- the linestage is direct coupled ... and the phono stage was NOT direct coupled.... Do we think the two can play together nicely this way?

timm,
Gotta dumb question, and it may have come up before. Please disregard if it has. Meant to ask this before. Curious.

1) do you have a phono unit plugged in to your preamp?
2) have you tried the same test with a different phono unit plugged in?

[timm]

Thanks decooney. No. Not a dumb question. Nothing plugged into the phono stage. Occurs without anything connected to phono , cd, etc. and w only the cd input utilized. Only time I don't get it is when tubes are out of phono stage.

I have yet to have an issue with anything with phono tubes out whether it be hum or blown fuse.

Guessing hum is around 250 hz or so since it is my midrange panel. One side has a louder hum than the other and this is with a cheater plug in to avoid any possible ground loops

[decooney]

Originally Posted by timm

Thanks decooney. No. Not a dumb question. Nothing plugged into the phono stage. Occurs without anything connected to phono , cd, etc. and w only the cd input utilized...

does the hum or tone of the noise change when you plug in a phono player to the phono jacks? Have you tested it with the phono plugged in to see if improves?

[timm]

So yes. I did just check this. Same issue. Hum across all inputs. Phono tubes removed - hum be gone.

[decooney]

Originally Posted by timm

So yes. I did just check this. Same issue. Hum across all inputs. Phono tubes removed - hum be gone.

timm,
Is your wall plug power stable - for certain? And, by chance do you have a whole bunch of different audio/video components all connected back to the same wall/plug circuit? Just curious, wondering if there is a ground issue or by adding the tubes just puts that pre/amp over the edge, along with any form of unstable power. Try another location, re-test. I ended up with a Richard Gray power station for these reasons.

[timm]

Only the amp and source - psaudio dac. Pre worked fine for 5 years??? On this electrical. As I said - no other problems with anything. Played on different circuit in house and everything else was different - amp, source, interconnects. Same problem. For it to only happen when the unit has played for at least an hour I thing again points to the unit - not the electrical

[decooney]

Originally Posted by timm

Only the amp and source - psaudio dac. Pre worked fine for 5 years??? On this electrical. As I said - no other problems with anything. Played on different circuit in house and everything else was different - amp, source, interconnects. Same problem. For it to only happen when the unit has played for at least an hour I thing again points to the unit - not the electrical

Something else to consider, some times things can rattle loose during shipping too or maybe a cold solder. Is there someone local who can go through and check all the connection points in that phono circuit vs shipping it all the way back again... you should have seen the wrapping DH did on my Inspire amp recently. Double boxing and more bubble wrap around the amp than I've even seen on any component I've ever received from any manufacturer in the past 40 years. Probably as a result of lessons learned and a lot of experience as I take it. Sh@# happens .

[timm]

so back to cary my slp98p went.... Sent it out yesterday.... Hoping for good results....

I narrowed it down to this -- after about 1 hour or more - (varied) - I would get a low level hum in the speakers - only when the phono tubes were in. This is with multiple sets of phono tubes. When I pulled the tubes and played the unit only thru the linestage - no problem. I had a turntable connected and disconnected while this happened.... At some point the fuse would blow in the power supply....

The hum was way easier to hear on my maggies - since it occurred in the midrange panel (not the bass panel).... On my other speakers (Martin Logan Odysseys) - the hum was actually in the woofer.... So, the hum must be at around 300 Hz or so given the crossover frequency of the Logan... I am not sure what it is exactly on the Maggie 20.7 - but bets are it is around 300hz to the mid panel.

Here are my bets.... Either something came loose as you said in shipping.... and as the solder gets warm the issue occurs.... or, there is an issue with them going direct in the linestage - and using the coupled capacitor approach in the phono stage. But, they didn't think that was an issue - or they wouldn't have done it that way initially.... What I don't want to hear is 'There doesn't seem to be a problem.....'

I am having them fix the remote volume - since that went wonky after I sent it in as well.... Fingers crossed .....

[Formerly YB-2]

timm - what amp(s) are you using to drive your Maggies?
Good luck with your SLP-98P. Thinking about one of those for my system.

[timm]

I have a sunfire signature. I think it does a really nice job. 425@8ohm and doubles down at 4.