[rob80b]

Regarding this thread, from what I understand the issue was just a minor wire dressing inside this 4B and has been taken care of by Bryton.
The trouble shooting which could be applied in another situation I find superfluous in this situation, so as not to give the wrong impression on another wise excellent amp I have asked James to delete or truncate this tread.

Robert

Original post.
Having just added a 4B SST to replace my 3B ST I am now experiencing hum and buzzing easily audible from a foot or two away from the speakers when the BP25P is plugged into the amp, balanced or single ended.
The 3B ST was dead quite from the speakers, nothing has changed in the set-up as I just disconnected the 3B and hooked up the 4B in the exact same manner.
Comparing the two amps so far the 3BST is the smoother of the two, contrary to what I’ve read from the majority of reviews.
The 4BSST has more energy in the highs (as if the EQ was slightly tilted up) but the grounding issue (buzzing) may most likely be the culprit interfering with the overall presentation. 

I’ve tried a few things, unplugging all devices, power cords and interconnects, bypassing the Veleodyne, change of interconnects still no luck, any ideas.

[James Tanner]

Hi Rob,

The GAIN and Bandwidth of the 4B and 3B are the same so there is no tilting up of frequency. Make sure the sensitivity switch on the back of the 4B is in the proper position to match the gain of your 3B ST.

'Hum' is usually ground loops, 'buzz' is generally RF. Try working backards from the amp -plug in just the amp and the speakers - does it hum?  plug in the preamp only does it hum?

Once it starts to hum let me know.

james

[rob80b]

Hi Rob,

The GAIN and Bandwidth of the 4B and 3B are the same so there is no tilting up of frequency. Make sure the sensitivity switch on the back of the 4B is in the proper position to match the gain of your 3B ST.

'Hum' is usually ground loops, 'buzz' is generally RF. Try working backards from the amp -plug in just the amp and the speakers - does it hum?  plug in the preamp only does it hum?

Once it starts to hum let me know.

james

Hi James,

You’re way too dedicated to be answering question first thing in the morning.
Anyway, I believe I have the gain set properly, 1 volt setting for the unbalanced and 2 v for the balanced input to match the 3BST.

Regarding the highs, I should have said on “some “ recordings, the 4B SST may be just too revealing for some discs having a slightly more open top end than the 3B ST, which is just a touch warmer.
Although the overall presentation of both amps is very similar the 4B SST , how can I say has a slight “savoir-faire” over the ST.

As for the hum/buzz, I’ll do a bit more trouble shooting if I have time this evening.
With just the speakers hooked up there is no hum, I should also mention that the hum does not increase with the volume and is present on all source selections even if everything else is powered down including the BP25.
In defining it’s characteristics, if I put my ear directly to the 4B a similar very small buzz can also be heard from the amp, which I think is normal without getting anal.

Robert

[James Tanner]

Bryston publishes a grounding trouble-shooting discussion, which I include here.  In 99 cases out of 100, this information serves to locate and eliminate the problem.  You can pass it along to the customer:


It is possible you have a 'ground loop' due to one or more of a number of possible causes:

One of these is the presence of more than one 3-prong line cord in your overall system. That could produce conflicting grounds between components in the system. 
The solution, if that is the case, is to make sure all 3-prong line cords return to a single plug-in location.

Another possibility is the connection of Video Cable from your Cable provider, to your sound system.  The outside Cable has a ground of its own, which often is not in agreement with the ground in your system.  The way to test this is to disconnect the Cable temporarily.  If the hum disappears, the Cable was the cause.  There are two possible solutions here:  One is to obtain a 'ground- breaker' HF transformer link for your Cable connection. 

Another is to contact the Cable company and have them reconnect their ground to agree with your house's wiring. In most jurisdictions, it is legally mandated for them to do so on your request.

A third possibility is hum picked up on the interconnects. This can happen if the input cables are longer than 10 feet, or if they are in close proximity to power connections.  The solution is to shorten and/or reposition the interconnect cables, or to use balanced XLR connections between your components where possible.

[rob80b]

Bryston publishes a grounding trouble-shooting discussion, which I include here.  In 99 cases out of 100, this information serves to locate and eliminate the problem.  You can pass it along to the customer:


It is possible you have a 'ground loop' due to one or more of a number of possible causes:

One of these is the presence of more than one 3-prong line cord in your overall system. That could produce conflicting grounds between components in the system. 
The solution, if that is the case, is to make sure all 3-prong line cords return to a single plug-in location.

Another possibility is the connection of Video Cable from your Cable provider, to your sound system.  The outside Cable has a ground of its own, which often is not in agreement with the ground in your system.  The way to test this is to disconnect the Cable temporarily.  If the hum disappears, the Cable was the cause.  There are two possible solutions here:  One is to obtain a 'ground- breaker' HF transformer link for your Cable connection. 

Another is to contact the Cable company and have them reconnect their ground to agree with your house's wiring. In most jurisdictions, it is legally mandated for them to do so on your request.

A third possibility is hum picked up on the interconnects. This can happen if the input cables are longer than 10 feet, or if they are in close proximity to power connections.  The solution is to shorten and/or reposition the interconnect cables, or to use balanced XLR connections between your components where possible.

Hi James,

I've covered all of of these issues; later, contrary to normal procedures I'll run an industrial extension from another outlet and try different combinations, and if I can find it I have a cheater plug around somewhere.

Not having this problem with the the 3B I'm a bit baffled.

Robert

[brucek]

Not having this problem with the the 3B I'm a bit baffled.

I do believe when Bryston changed from the ST to SST models they modified the ground lift circuit.

It used to be a simple 10 ohm power resistor that was quite effective in removing ground loops, but the SST models employ galvanic isolation instead by installing a high current bridge for this purpose. Perhaps tighter standards put forth by the CSA or whatever was the reason? It may not be quite as effective as the old switch and resistor method. James can comment on that.

Anyway, there was a change in the isolation between AC and DC ground that would account for the difference in the two amps....

brucek

[James Tanner]

Not having this problem with the the 3B I'm a bit baffled.

I do believe when Bryston changed from the ST to SST models they modified the ground lift circuit.

It used to be a simple 10 ohm power resistor that was quite effective in removing ground loops, but the SST models employ galvanic isolation instead by installing a high current bridge for this purpose. Perhaps tighter standards put forth by the CSA or whatever was the reason? It may not be quite as effective as the old switch and resistor method. James can comment on that.

Anyway, there was a change in the isolation between AC and DC ground that would account for the difference in the two amps....

brucek

Hi James;
 
The grounding system we use at present still has the 10-Ohm resistor between AC and signal grounds.  The only difference is that there is now a high-current bridge in parallel with the resistor.  It allows a maximum of 1.2 Volts of difference between those grounds.

If there is a higher Voltage difference present in the grounds, that could account for the fact that there is now hum in the system, but it would also mean that there is a rather serious potential problem in the grounds of the house, perhaps with the Cable.  I would recommend investigating why there is so much ground difference Voltage floating around and correct it.
 
cwr

[rob80b]

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

Robert

[jethro]

Robert,

Have you tried the 3B-ST back into your system to rule out accidental damage to the cabling ?

I had problems a while ago with using cheap halogen lights which caused my 4B-ST to make awful noises.
The lights were on a different circuit but it still caused problems somehow. Do you have halogen lights ?

[rob80b]

Robert,

Have you tried the 3B-ST back into your system to rule out accidental damage to the cabling ?

Yes,  I just found my Tripp Lite tester so I'll check everything tonight, some of these older buildings hold surprises.

[James Tanner]

Robert,

Have you tried the 3B-ST back into your system to rule out accidental damage to the cabling ?

Yes,  I just found my Tripp Lite tester so I'll check everything tonight, some of these older buildings hold surprises.

Maybe a Torus is in your future?

james

[NewBuyer]

Perhaps the source component is picking up interference emitting from the 4B (e.g. from the 4B's internal transformer, etc) that was somehow not present from the 3B?

I once had a DAC that would pick up hum from certain components when placed in close proximity, and putting more distance between them eliminated the hum.

How close is your source to your amp - are they right next to each other, can you try increasing the distance?

[rob80b]

Ok, I’ve continued with some more troubleshooting..
Here’s the synopsis so far, with everything disconnected and unplugged except the speakers and the amp no noise, if I only the BP25 is connected to the 4B I get the hum and if I insert just an interconnect into the 4B regardless of length without attaching it to anything I get the hum back, balanced interconnects do reduce the problem but only marginally.
I’ve tried four different interconnects, from AudioQuest, JP Labs, Canare and Bluejeans so I’ve ruled out the interconnect, and I’ve switched power cords
I’ve tried lifting the ground of the amp and preamp individually without positive results.
Last, running an industrial extension from a different outlet, not on the same line, gave the same results.
Anything I’ve missed?

Robert

[James Tanner]

Hi Rob,

Sounds like you exhausted the options.  What about the ground potential differences Chris mentioned.
What dealer did you get the 4B from - is there a chance they could try it in their store and see if they get the same results?

james

[georgev]

Hi Robert,

My TV cable caused hum in my speakers.  I had to unplug the TV cable before listening to music.  Hope this helps you.

George.

[Phil A]

Ok, I’ve continued with some more troubleshooting..
Here’s the synopsis so far, with everything disconnected and unplugged except the speakers and the amp no noise, if I only the BP25 is connected to the 4B I get the hum and if I insert just an interconnect into the 4B regardless of length without attaching it to anything I get the hum back, balanced interconnects do reduce the problem but only marginally.
I’ve tried four different interconnects, from AudioQuest, JP Labs, Canare and Bluejeans so I’ve ruled out the interconnect, and I’ve switched power cords
I’ve tried lifting the ground of the amp and preamp individually without positive results.
Last, running an industrial extension from a different outlet, not on the same line, gave the same results.
Anything I’ve missed?

Robert

As noted in the prior post, a cable box if on and even if not connected (to the equipment) can cause a ground loop issue.  See this for more info:

http://www.audioholics.com/tweaks/connecting-your-system/ground-loops-eliminating-system-hum-and-buzz

[rob80b]

Hi Rob,

Sounds like you exhausted the options.  What about the ground potential differences Chris mentioned.
What dealer did you get the 4B from - is there a chance they could try it in their store and see if they get the same results?

james

"Hi James;
 
The grounding system we use at present still has the 10-Ohm resistor between AC and signal grounds.  The only difference is that there is now a high-current bridge in parallel with the resistor.  It allows a maximum of 1.2 Volts of difference between those grounds.

If there is a higher Voltage difference present in the grounds, that could account for the fact that there is now hum in the system, but it would also mean that there is a rather serious potential problem in the grounds of the house, perhaps with the Cable.  I would recommend investigating why there is so much ground difference Voltage floating around and correct it.
 
cwr"


Hi James

This could indeed be the problem as I just checked all of the outlets and some are not grounded at all. I’m currently renting as we’ve just sold the house so rewiring may be out of the question.
Although I do find it a bit odd having the 4B emitting a hum/buzz through the speakers when none existed with the 3BST.
The 4B was purchased used (could not resist) but originally came from Kennedy Hi-Fi in Markham, the previous owner has gone to a 9BSST for HT. I’ll email him to see if he ever noticed any problems
If I get a chance I’ll it run out to Rexdale or get Bay Bloor to check it next month when I order in my BCD-1.

And once again thanks for yours and Bryston’s continual commitment and dedication in helping out the end users.

Robert

[rob80b]

As a footnote; I’ve just sat down listened to Dave Holland’s “Emerald Tears” on vinyl before retiring for the evening and it’s hard to imagine getting a clearer in-sight into the recording, even with my current grounding issue.

[rob80b]

Continuing with this saga, I’ve started testing all the outlets in the apartment, some are not grounded and some are wired in reverse, these will throw the ground to hot, but this will only show up if a devise with a ground plug is inserted, fun stuff ehh.
So once I correct all the polarities and level the playing field I’ll report back with the results, it may take me a few days though as I'm just going to relax and listen to some music.

[rob80b]

Found this, which I'll go through tomorrow  when I have time.
http://www.iso-max.com/an/an004.pdf

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.
The other issue may just be the fact that the 4BSST being a more powerful amp is only showing up a problem that already existed in my ac lines.

I would also like to know if anyone has ever tried to run a separate ground independent of the house current, therefore defeating the main ground from the outlet and attaching it to a new earth ground.

Robert