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back to ask again long sorry

If you recognize the user-ID, then you know the problem I'm about to describe because I've been yapping about it in these forums, on and off, for *years*. I'm only in here to try again because everything I've done so far to try to fix it has resulted in just more credit-card bills.

The sound is perfect for the first twenty or thirty minutes -- always has been, and I always think I've fixed whatever's wrong -- and then, gradually, the sound becomes reedy and increasingly sibilant in the upper midrange and apparently "over-modulated" right around the midrange-tweeter crossover.

If I shut everything off and reconnect everything, the problem often goes away for another twenty or thirty minutes, but not always.

It can't be a problem with components or speakers because everything in the chain has been repeatedly replaced, and many configurations have been sent off for service and returned with clean bills of health.

I don't think it's RF pollution because I've encountered the problem at a friend's house, and fixed it doing the same thing, over there: reconnected everything and had great sound for... twenty minutes.

I don't think it's a cracked RCA input socket because the problem has spanned several configurations of equipment.

I don't think it's a bad interconnect because the problem has spanned several configurations of cabling.

I don't think I'm delusional because non-audiophile listeners have commented on both the unpleasantness of the sound before reconnection, and the improvement afterward.

At all events, something seems to be "building up" in the signal path, somewhere, and the act of severing all the connections seems to cause whatever that build-up is, to be dissipated.

Lately I've been trying to fix this by... well... *reading* -- about everything from PS-Audio Humbusters to Audience Adept Response power conditioners and back to the XDC power filters by Channel Islands Audio. Trouble is, I'm cleaned-out financially and I just really don't feel like spending any more money before knowing with a bit more certainty that more dollars spent will point me more definitively toward getting to the bottom of this. Are there professionals who can help to diagnose the problem, and who are then also knowledgeable enough about the industry to recommend the proper fix?

Current system configuration: (many, many others have been tried!)

McCormack MAP-1 and DNA-HT5, connected directly to dedicated AC circuit via Signal Cable power cords

Arcam FMJ-CD23 connected directly to nearby, undedicated AC circuit, via signal cable digital power cord

Sony BDP-S550 blu-ray player and Panasonic TX50 plasma TV, connected to APC H-15 power supply, which is in turn connected to the undedicated AC circuit via Harmony power cord

Salk Songtower QWT speakers, front L and R, Linn Trikan center channel, Totem Mite-T rear L and R.

signal cable interconnects, element cable cross-connected speaker cables.

Thanks again, everybody.

Dave O'Gorman
Gainesville, Florida
dog_or_man
almarg's avatar
almarg
8,673 posts
 
Whoa! So the whole system (chassis ground and signal ground of all components, as well as all interconnect shields) are completely floating relative to ac hot and ac neutral.

Seems to me that that is your problem!!

And beyond that, I wonder if ac neutral is connected to a true earth ground near the breaker box and the ac inlet to the house. If not, as you said you may potentially (no pun intended) have worse problems than with your audio system. Such as no safe path to ground for lightning that may hit the power lines. Your electrician friend definitely has some things to check out.

Assuming this more serious potential problem is ok, as far as the audio problem is concerned I would try (as a temporary experimental fix, pending getting the wiring redone) simply connecting a wire from the chassis of one and only one component (probably the preamp) to a known earth ground (such as a cold water pipe, a copper stake driven into the ground, etc). That could very well resolve the problem, it seems to me.

Regards,
-- Al
jea48
2,944 posts
 
.....connecting a wire from the chassis of one and only one component (probably the preamp) to a known earth ground (such as a cold water pipe, a copper stake driven into the ground, etc). That could very well resolve the problem, it seems to me.
Careful there Al.... That may not be good advice. We have no way of knowing when the house was built. We only know at this point it was around 1949 from the info given for the Square D panel. And we do not even know that for sure because the house could of been updated in 1949.

The power company's 120/240V overhead lateral service drop is triplex attached to an eye bolt connected to the service entrance conductors via way of the weather head. Though the service is old looking it still looks at least late 50s or newer to me. Kind of hard to tell from just looking at the pictures.... I can't quite figure out why the main breaker is a 3 pole 60 instead of a 2 pole 60 though. That is if that is the main.

I am sure at some point the main service entrance neutral conductor was connected to earth. That has been the norm for many many years. Also for many years if the incoming domestic water line is metallic then that shall be the earth connection for the service neutral conductor. At this point we can only assume the neutral is still connected to earth.

Just guessing from looking at the pictures the last picture is the main panel. Again only guessing. If this is indeed the main panel then the neutral bonding to the enclosure as well the connection to earth ground was done here..... If the electrician ran a new dedicated line from this panel, which is how I read Dog_or_mans post he should have an equipment ground at the receptacle. I can't imagine an electrician installing a branch circuit today with out an equipment grounding conductor. Who knows.....

What I do know the safety equipment grounding conductor needs go back to the panel the branch circuit is fed from and connected to ground there. If a ground is not present at that panel then the grounding conductor should be extended and connected in the panel where service entrance neutral is bonded, connected, to earth.

03-20-09: Dog_or_man
The main electrical system of the house has no safety ground whatsoever ("the third pin on these outlets is just for show, Dave")
Old house wiring Branch circuits with out equipment grounding conductors is nothing new. And yes many a home owner have replaced old worn out 2 wire receptacles with new 3 wire type. Legal to do so? No.....

At any rate because there is not an equipment grounding conductor present at an outlet that does not mean the main electrical AC service is not bonded, connected, to earth.
If the service entrance neutral conductor is no longer connected to earth for what ever reason I can't imagine any electrician would leave it that way.
almarg's avatar
almarg
8,673 posts
 
OK, thanks Jim. Perhaps I misinterpreted Dave's post, and maybe he meant that the dedicated line does have a safety ground, and one which has a proper complete path back to earth, while it is just in the rest of the house that there are some 3-wire outlets with the safety ground not connected. We'll await Dave's confirmation that that is what he meant.

Regards,
-- Al
dog_or_man OP
68 posts
 
The dedicated line has a safety ground.
jea48
2,944 posts
 
03-20-09: Dog_or_man
The dedicated line has a safety ground.

Dog_or_man,

If I could make a couple of suggestions.
First it appears part of your equipment is plugged into an old 2 wire branch circuit fed from the old Square D panel. The new 120V 3wire dedicated branch circuit is fed from the other GE electrical panel, which I assume is the main electrical panel. I personally would not feed an audio system connected together by ics from two different panels. Plug all your equipment just into the new dedicated branch circuit......

After you connect everything to the new dedicated circuit I would like you to try an experiment.

Power up your system put on some music and set the volume level to a moderate listening level. Then leave room go do something else for at least 30 minutes. After 30 minutes has past return to the room. Adjust the volume level to where you normally listen to your music. Then sit down and listen......

What is your first impression? Does everything sound ok?
After 20 or 30 minutes of listening does everything still sound the same way or worse as you have experienced in the past.

Post back your results.
Jim
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