4B SST grounding issue?

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brucek

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Re: 4B SST grounding issue?
« Reply #20 on: 25 May 2008, 07:46 pm »


Quote
Although the grounding scheme is slightly different from the the ST series it would be informative to know if this modification could be the cause
of the induced hum I'm now experiencing which did not exist with my 3BST.

I'd say likely not, given the following quotes from yourself through this thread:

........Tried a cheater plug as a temporary solution on the BP25 and then the 4B and ......no luck.

........I’ve tried lifting the ground of the amp and preamp individually without positive results

Once you lift the safety ground with a cheater, the scheme used to connect AC and signal ground is inconsequential.

If I was experiencing your situation, I would take my preamp and amp to a friends house (who has a dedicated and properly wired circuit), and do a test to see if perhaps the new amp is at fault.

When I read the statements below, I simply wouldn't trust anything that's happening. You need to establish if the amp is OK...

......I just checked all of the outlets and some are not grounded at all

.......I’ve started testing all the outlets in the apartment, some are not grounded and some are wired in reverse

brucek

rob80b

Re: 4B SST grounding issue?
« Reply #21 on: 26 May 2008, 01:10 am »

Once you lift the safety ground with a cheater, the scheme used to connect AC and signal ground is inconsequential.

If I was experiencing your situation, I would take my preamp and amp to a friends house (who has a dedicated and properly wired circuit), and do a test to see if perhaps the new amp is at fault.

brucek

Hi Brucek

I thought the same thing about lifting the safety ground but there may be residual noise on the line itself.
Spent the better part of this morning testing and correcting all the outlets, still getting the hum/buzz but at a slightly lower level I think.
Getting the amp to another location is easier said than done, it's a 60 pound beast plus being a small business owner being busy 6 1/2 days a week makes it difficult.

Robert

Bassmann

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Re: 4B SST grounding issue?
« Reply #22 on: 26 May 2008, 04:38 pm »
Hi Rob
I have a 4BSST which I've owned from new. I find mine ok with regards to the hum/buzz that you seem to be experiencing.I find that if the amps are on with no music playing and all is quiet in my room that I can hear a faint humming coming from the power amp transformers. I think this is normal though considering the electrical power reserves that it has. I live in a small village in England with not so many houses and just a few small engineering businesses, Im also quiet close to the sub station as well I think.

Is there a lot of industry near where you live that would be drawing large currents off the same supply?, also do you know what speakers the amp was driving before, ie has it had a hard life.

rob80b

Re: 4B SST grounding issue?
« Reply #23 on: 26 May 2008, 07:28 pm »
Ok, for those who are curious here's where I'm at.

I've now discovered that if only one interconnect is plugged into the 4BSST , left or right channel, with everything plugged in, connected and powered up there is no hum on either channel. Repeat the procedure for the other channel, same thing dead quiet.
Now, to figure out why with both channels plugged it causes the buzz/hum.

Robert
« Last Edit: 26 May 2008, 08:30 pm by rob80b »

rob80b

Re: 4B SST grounding issue?
« Reply #24 on: 26 May 2008, 09:49 pm »
Next brilliant idea! ; Made up an interconnect with the ground disconnected, therefore the sleeve does not ground to the in jack, thinking that maybe there is a conflict with the ground on the inputs.
Powered everything up, now I get a louder hum/buzz only on the left channel with the modified cable, but the other channel is quiet no hum-buzz. Played some audio, both channels are audible Reversed the procedure, reversed the results
Powered down the amp, swapped cables, now I’m back where I started, buzz/hum on both channels.
So is it a ground loop problem from the mains or the 4BSST itself, there must be an obvious piece to the puzzle that I’m missing.
The saga continues.

smerlas

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Re: 4B SST grounding issue?
« Reply #25 on: 28 May 2008, 12:13 am »
OK ........... silly question time. :?  Do you still have the 3B you upgraded?  If you do, what happens if you put it back in the system, does the problem go away?

You seam to have gotten away from the original question regarding the differences in the previous line of amps and the SST series and if a difference in the amplifier series would be causing the hum.

If you had the electrical problems before they should have presented the same effect.  I wonder if switching the amp has just brought to the forefront a problem you had before.

If you have it you may want to put it back in the system before dragging equipment all over the place or a complete remodel of the place ............ sounds like you have a good start on that one.  :lol:

You may have damaged an interconnect in swapping out the amp.

Oh yeah .............. forgot to mention I have the 4BSST and it is eerily quite .............. the volume can be at 1/2 level and a CD has ended and there is NO and I mean NO noise.

rob80b

Re: 4B SST grounding issue?
« Reply #26 on: 28 May 2008, 02:41 am »
Hi Smerles,

I've reconnected the 3BST a number of times just to check on each configuration and now have it reinstalled, no noise from the the speakers  it's dead quiet with my ear to the drivers.
Interconnects I checked and swapped over and over, ran current from different outlets and cut the breakers for every socket just to be sure.
After connecting the 4B I checked all the outlets for polarity and grounding, some were actually incorrectly wired, which I corrected but never affected the 3BST as they were. Tried lifting the grounds, still to no avail. I've also have headphone amps and a number of high end headphones which never showed up any grounding problems.

As I mentioned yesterday, I made the discovery (which escaped at the beginning) that by disconnecting one interconnect from the 4B even when everything is connected and powered up the system was dead quite.I reversed the procedure for the other channel, same results.
Logic leaves me to believe that there must be a grounding problem between the dual mono configuration of this 4B, I spent over 20 years doing Electro-acoustic music production and sometimes dealt with hundreds of cables, which of course became a nightmare in tracking down a ground loop so this simple set up has me scratching my head, (ok, pulling out my hair).

Bottom line is, with the 3B installed in the exact configuration there is no hum-buzz, just silence, that is until I hit the play button. 
With the 4B the noise from the speakers is audible from the listening position or anywhere in the room.
I should also mention that the reverse is true for the mechanical noise, the 3BST is much louder than the 4BSST which for an amp that size is almost dead quiet even with your ear to the chassis.

"I wonder if switching the amp has just brought to the forefront a problem you had before."
I've given this aspect a serious consideration and hope this is not the case as it would entail redoing the wiring (not practical as I'm currently renting, sold the house) or investing in something like a Torus which could get a bit pricing for a problem that did not surface before.

So I've gone ahead and boxed up the 4B to send to Bryston, if the unit is 100% then I'll will probably resell it, tryout a 3BSST (with my fingers crossed) or  keep it in storage till I relocate, but I must say that I really  appreciate the help from Bryston and the feedback in trying to solve this problem. Even with the noise problem I'm still able to hear the improvements Bryston implicated in the SST series and would be sad to see it go.
If Bryston do ascertain that there is indeed a problem with the unit I'll be happy and be able to just sit back and enjoy the music, that is after I pickup my BCD-1 next month though.

Robert

rob80b

Re: 4B SST grounding issue?
« Reply #27 on: 28 May 2008, 03:20 am »
One more thing I forgot to mention, in case someone brings it up, is that I tried an unbalanced and a  fully balanced setup from source to amp.

vegasdave

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Re: 4B SST grounding issue?
« Reply #28 on: 29 May 2008, 01:09 am »
Oh yeah .............. forgot to mention I have the 4BSST and it is eerily quite .............. the volume can be at 1/2 level and a CD has ended and there is NO and I mean NO noise.

Same here. No problems whatsoever...I'd say it'll be a long time before it goes back to the factory for a check-up.

rob80b

Re: 4B SST grounding issue?
« Reply #29 on: 29 May 2008, 03:37 pm »
Oh yeah .............. forgot to mention I have the 4BSST and it is eerily quite .............. the volume can be at 1/2 level and a CD has ended and there is NO and I mean NO noise.

Same here. No problems whatsoever...I'd say it'll be a long time before it goes back to the factory for a check-up.

Hi Guys,

In the last twenty years or more my brother and I have gone through a 2BLP, 3B, 3NRB, 3BST and a 4BST also the .5, .4 and a BP25P pre-amps with no little or no problems. The 3B NRB developed a cracking noise but this 4BSST is the first unit I've experienced a grounding issue with.
Everything else was bought new but with the price of the units todays I felt totally confident in purchasing the 4BSST second hand.
The 4BSST will be off to Bryston so hopefully we will get to the bottom of this one way or another, in the mean time the 3BST is back in it's place to retain the silence.

robert


James Tanner

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Re: 4B SST grounding issue?
« Reply #30 on: 11 Jun 2008, 03:06 pm »
Oh yeah .............. forgot to mention I have the 4BSST and it is eerily quite .............. the volume can be at 1/2 level and a CD has ended and there is NO and I mean NO noise.

Same here. No problems whatsoever...I'd say it'll be a long time before it goes back to the factory for a check-up.

Hi Guys,

In the last twenty years or more my brother and I have gone through a 2BLP, 3B, 3NRB, 3BST and a 4BST also the .5, .4 and a BP25P pre-amps with no little or no problems. The 3B NRB developed a cracking noise but this 4BSST is the first unit I've experienced a grounding issue with.
Everything else was bought new but with the price of the units todays I felt totally confident in purchasing the 4BSST second hand.
The 4BSST will be off to Bryston so hopefully we will get to the bottom of this one way or another, in the mean time the 3BST is back in it's place to retain the silence.

robert



Hi Rob,

Well our apology sir we did find a problem with your 4B SST.  Amp is fixed and on the way back home.

james

rob80b

Re: 4B SST grounding issue?
« Reply #31 on: 11 Jun 2008, 03:42 pm »

Hi Rob,

Well our apology sir we did find a problem with your 4B SST.  Amp is fixed and on the way back home.

james


Hi James,

No apology necessary, these things happen time to time to the best of us.

Robert

rob80b

Re: 4B SST grounding issue?
« Reply #32 on: 11 Jun 2008, 03:59 pm »

Hi Rob,

Well our apology sir we did find a problem with your 4B SST.  Amp is fixed and on the way back home.

james


Hi James,

No apology necessary, these things happen time to time to the best of us.

Robert


Well okay, on second thought after having gone through a week of trouble shooting and then sending the 4B away for a week or more I accept your apology, but just this time.

Robert

rob80b

Re: 4B SST grounding issue?
« Reply #33 on: 17 Jun 2008, 05:44 pm »
Well we got the beast back today from Bryston; noise has been greatly reduced from what I can tell, still there but you need to be about few inches from the drivers to hear it as apposed from across the room.
Interesting though that the same scenario applies, disconnect one cable and all is quiet.
Hopefully I can live with it and not get too neurotic, as this 4B will most likely be my last amp for many years to come if not the last.

Robert

NewBuyer

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Re: 4B SST grounding issue?
« Reply #34 on: 17 Jun 2008, 08:59 pm »
So even after servicing, the noise (although reduced) still presents itself when even one interconnect cable is attached? Weird - I was hoping the issue would have been totally resolved...

rob80b

Re: 4B SST grounding issue?
« Reply #35 on: 17 Jun 2008, 10:03 pm »
So even after servicing, the noise (although reduced) still presents itself when even one interconnect cable is attached? Weird - I was hoping the issue would have been totally resolved...

Actually the other way around, when both cables are connected there is a very sight buzz/hum (and I do mean slight, no where near what it was before) and none when one cable is disconnected.
I've yet to retry my balanced cables, will do that this evening if I have time.

rob80b

Re: 4B SST grounding issue?
« Reply #36 on: 18 Jun 2008, 02:26 am »
Following up with balanced interconnects is that there is no hum or buzz, any noise present is probably residual contamination from upstream components.
And once again with unbalanced my ear has to be next to the drivers to hear it.