[mlawson66]

Hi,

I've recently upgraded my system. I replaced my old Sherwood Newcastle P-965 with a Bryston SP2. I've got 5 Reference 9's in my system, a pair for the surrounds, a pair for the rears, and one for the center. I leave them on all the time. They are arranged in a stack, with 1 inch spacers beneath the feet, for better ventilation.

After upgrading to the Bryston SP2, when I turn off the pre/pro, I get white noise coming out of the rear speakers.  I'm being told that somehow, the RF generated by the Reference 9s is being fed back into the system and causing this. It seems strange that this only happens on the 2 rear speakers.

Also, I've been cautioned by someone else, that I should turn off the Reference 9's when I turn off my HT pre/pro. I didn't think this was necessary. It seems like a sensible precaution, so I thought I should get the official statement on this. It is a little difficult to get to the back of my little Pyramid of Power to turn off each of the 5 amps individually. I guess I could get a power strip for this purpose.

So, for the record:

1) Should the Reference 9's be turned off when the preamp that they are connected to is turned off?
   a) Is there any danger of over heating?
   b) Is there any fire danger?

2) Is there any way that RF generated in the power module of the Reference 9 could cause white noise or static in my system?
   a) Is it possible that the RF generated in the PWM could be fed back out of the system via RCA unbalanced input?
   b) Should there be some sort of special shielding to keep this RF from the rest of the components in my system?


If it turns out that we should be shutting down our Reference 9's when the preamp that they are connected to is turned off, shouldn't there be a remote trigger relay on the amp, or maybe the power switch should be on the front?

Thanks!

By the way, the new Reference 9's Rock!  I've been very happy with them. I don't think that there are any problems with them. I just want to get the straight story on these issues.

[nuforce-casey]

After upgrading to the Bryston SP2, when I turn off the pre/pro, I get white noise coming out of the rear speakers.  I'm being told that somehow, the RF generated by the Reference 9s is being fed back into the system and causing this. It seems strange that this only happens on the 2 rear speakers.

Please send email to support and describe in detail how the white noise is behaving: (1) noise when Pre/Pro is off and the Ref9 is on, then it's the residual from the Pre/Pro; or (2) white noise when turning off Ref9 while Pre/Pro is on?

In a 7.1 pre/pro, the rear channels are actually mono, it could be the treatment of the signal layout that causes the rear mono channels to behave differently than the other discrete channels. 

Also, I've been cautioned by someone else, that I should turn off the Reference 9's when I turn off my HT pre/pro. I didn't think this was necessary. It seems like a sensible precaution, so I thought I should get the official statement on this. It is a little difficult to get to the back of my little Pyramid of Power to turn off each of the 5 amps individually. I guess I could get a power strip for this purpose.

We recommend this approach because an unterminated and long antenna can pick up and inject environment noise into Ref9, which could have enough energy to cause damages while unattended.   The Ref9 comes with safe guard to prevent overheating and short-circuit, there will be no hazzard.  However, a scenario such as '70Khz noise being amplified and driving the ribbon tweeter', thought not audible, is still not a good thing to have.

2) Is there any way that RF generated in the power module of the Reference 9 could cause white noise or static in my system?
   a) Is it possible that the RF generated in the PWM could be fed back out of the system via RCA unbalanced input?
   b) Should there be some sort of special shielding to keep this RF from the rest of the components in my system?

It is possible, but we haven't seen it.  The best safeguard is a robust ground that captures all noise.

If it turns out that we should be shutting down our Reference 9's when the preamp that they are connected to is turned off, shouldn't there be a remote trigger relay on the amp, or maybe the power switch should be on the front?

We have a special Monster Cable product for $190 that can do all these.  Or, just leave the Pre/Pro on all the time? 

[mlawson66]

After upgrading to the Bryston SP2, when I turn off the pre/pro, I get white noise coming out of the rear speakers.  I'm being told that somehow, the RF generated by the Reference 9s is being fed back into the system and causing this. It seems strange that this only happens on the 2 rear speakers.

Please send email to support and describe in detail how the white noise is behaving: (1) noise when Pre/Pro is off and the Ref9 is on, then it's the residual from the Pre/Pro; or (2) white noise when turning off Ref9 while Pre/Pro is on?

1) The noise, something between bacon sizzling, and the sound of the sea, happens about 15 seconds after turning off the pre/pro. It ramps up over the last 5 seconds. It sounds very much like it comes on as a power supply capacitor in the pre/pro discharges.

2) The noise goes away when the pre/pro is turned on.

In a 7.1 pre/pro, the rear channels are actually mono, it could be the treatment of the signal layout that causes the rear mono channels to behave differently than the other discrete channels. 

The folks at Bryston indicated that several of the surround processing modes, the rear channels on the SP2 are not mono. From observation, it seems like there is a chorus or some similar sort of effect in play on the rear channels.

Also, I've been cautioned by someone else, that I should turn off the Reference 9's when I turn off my HT pre/pro. I didn't think this was necessary. It seems like a sensible precaution, so I thought I should get the official statement on this. It is a little difficult to get to the back of my little Pyramid of Power to turn off each of the 5 amps individually. I guess I could get a power strip for this purpose.

We recommend this approach because an unterminated and long antenna can pick up and inject environment noise into Ref9, which could have enough energy to cause damages while unattended.   

In my case, this "long antenna" is a 3 foot, very well shielded, RCA cable. It doesn't seem like much of an antenna. I suspect that there is a semiconductor junction in the preamp that looks like a diode when the system is powered down. This could look like a simple detector circuit. Later this weekend, I'll try an "analog"  amp in this circuit to see of the problem persists.

If it is suggested that the amps be turned off when their source component is turned off, isn't it a poor design to put the power switch in the rear? Wouldn't it be even better to include a power relay that could be triggered by the preamp? I've got several other amps in my system that don't pick up noise when the preamp is turned off. It would be optimal to be able to leave the amps on all the time, like the amps in the rest of my system.

Also, since this only happens with the 2 rear speakers, what is the official word? Turn off the 2 rears, and leave the other 3 on, or turn them all off?

The Ref9 comes with safe guard to prevent overheating and short-circuit, there will be no hazard.  However, a scenario such as '70Khz noise being amplified and driving the ribbon tweeter', thought not audible, is still not a good thing to have.

I have it on good authority, that someone just had 2 boards fry, after the source device, an NHT xover in this case, automatically shut down. If boards are still frying, I'm concerned that there may be a fire hazard issue.

2) Is there any way that RF generated in the power module of the Reference 9 could cause white noise or static in my system?
   a) Is it possible that the RF generated in the PWM could be fed back out of the system via RCA unbalanced input?
   b) Should there be some sort of special shielding to keep this RF from the rest of the components in my system?

It is possible, but we haven't seen it.  The best safeguard is a robust ground that captures all noise.

I'm pretty sure that this isn't an issue. I just wanted to know if you folks had any documented cases of this being an issue.

If it turns out that we should be shutting down our Reference 9's when the preamp that they are connected to is turned off, shouldn't there be a remote trigger relay on the amp, or maybe the power switch should be on the front?

We have a special Monster Cable product for $190 that can do all these.  Or, just leave the Pre/Pro on all the time? 

1) I don't think the weird whistle and pop that these amps make when they are shut down is very good for the speakers, so I really don't want to be turning them off all the time.

2) I've got too many remotes already! I think my wife would divorce me if I added 1 more!  If this Monster Cable product does accept a remote trigger, well I guess this is safer than fried boards, damaged speakers, or possibly a burnt house! It is apparent that these amps were not designed to be turned off often. If we are supposed to turn them off with our source components now, having the power switch in back is a major design flaw. I've got 5 of these now. Turning them off 1 at a time requires moving equipment around to get at the power switches. If you guys are going to charge me $190 for your design flaw, I'm going to get a little grumpy!

3) Leaving the preamp on all the time sounds like a good idea. Unfortunately, every preamp that I've owned stays off after a power outage. I live near Seattle. We lose power here on the order of 10 to 20 times a year. Sure, I leave the preamp on, muted, all the time for now. I'm trusting that if the power goes off, I'll wake up when it comes back on, and turn my preamp back on. Otherwise, I could wake up to a fried amp, damaged speakers, or worst of all, a fire! This could happen at work, and I wouldn't even know about it until I got a call from the fire department!