[mschlack]

I get a low level hum or buzz from my speakers when my Stratos is on that I can't seem to eliminate. After much troubleshooting, here's the story:

With all audio and video devices unplugged from the wall and my pre, and with the Stratos plugged into a dedicated power line I get a hum when the amp is connected to my pre, even when a)the pre is unplugged and b)no sources are plugged into it. Removing ONE interconnect kills the hum in both speakers.

I normally run MIT AVT1 cables, but have tried Kimber (no grounded shield) and several others. No difference. I have tried with and without ground pin on the power cable.

The hum varies in volume and sometimes is not that noticeable but other times drives me baty. I have a redboard model.


Looking for ideas on taming this.

[avahifi]

Does either or both your amp and preamp have three wire ac power plugs?

Frank Van Alstine

[lazydays]

I get a low level hum or buzz from my speakers when my Stratos is on that I can't seem to eliminate. After much troubleshooting, here's the story:

With all audio and video devices unplugged from the wall and my pre, and with the Stratos plugged into a dedicated power line I get a hum when the amp is connected to my pre, even when a)the pre is unplugged and b)no sources are plugged into it. Removing ONE interconnect kills the hum in both speakers.

I normally run MIT AVT1 cables, but have tried Kimber (no grounded shield) and several others. No difference. I have tried with and without ground pin on the power cable.

The hum varies in volume and sometimes is not that noticeable but other times drives me baty. I have a redboard model.


Looking for ideas on taming this.

I had a similar hum a few years back, and it ended up being a bad solderiing joint on one of the interconnects.
gary

[mschlack]

Does either or both your amp and preamp have three wire ac power plugs?

Frank Van Alstine

Yes, both do. But I have tried removing the ground lug connection (used an extension chord with no third prong). And I should stresss that I get this problem with the pre off and unplugged, as long as both interconnects are connected between the pre and the amp.

[avahifi]

Did you use separate no three wire AC connections on both units at the same time or were they both plugged into the same AC power cord?

Frank

[mschlack]

Did you use separate no three wire AC connections on both units at the same time or were they both plugged into the same AC power cord?

Frank

I tried removing the third wire on the amp while connected to the pre completely unplugged. I haven't tried it with both pre and amp connected with two-wires -- not sure how that would be different than having the pre unpluged.

[Niteshade]

You should contact the manufacturer. It sounds like the amp's chassis has EMI "hot spots" and one channel is clear of them while the other is not. When both cables are plugged into the pre, you're distributing the noise to the other channel's ground system. This only happens if both channels are plugged into the pre, even if the pre is unplugged form the power source. Does that sound like what's happening?

Grounds are funny beasts: In a schematic they can appear to be connected to the same buss, but in reality they are not and noise can freely roam on a ground buss, inch by inch.

[mschlack]

You should contact the manufacturer. It sounds like the amp's chassis has EMI "hot spots" and one channel is clear of them while the other is not. When both cables are plugged into the pre, you're distributing the noise to the other channel's ground system. This only happens if both channels are plugged into the pre, even if the pre is unplugged form the power source. Does that sound like what's happening?

Grounds are funny beasts: In a schematic they can appear to be connected to the same buss, but in reality they are not and noise can freely roam on a ground buss, inch by inch.

Yes, that sounds like it -- quite plausible. If you know, what would I be asking the manufacturer to do? In other words, is this a bad solder joint (or some other mfg. issue) or a bad design? And what would be some of the remedies for that?

[Niteshade]

This is a rather abstract issue since it deals with the flow of ground currents through solid metal. It's almost like fish swimming in a pond. I have a feeling that it's a simpler issue (hopefully) and due to a poor internal ground connection. Sometimes when this happens, the poorly grounded area "reroutes" through other things and picks up noise. An engineer there might know what's going on quickly (it might be a known weakness, something that happens from time to time). I would imagine most of their amps don't do this and you just happen to get lucky, so I don't believe it's an inherent design flaw.

[Nicholas Bedworth]

I've had a similar experience with Stratos Glass Ceiling unit.

With NO audio cabling attached to the amp, there is a faint, rapid, click-like buzz in the tweeter, almost like the noise from Triac light dimmers (which I have in the house, but they're all, in theory, turned off).

And there is a faint 120 Hz hum in the woofers (the speakers being Be-718s).

The Stratos is on its own 20 Amp circuit, no other gear attached. And I've tried running with a cheater plug to no avail.

Also, on rare occasions, there is a mechanical humming from the chassis, which doesn't increase or decrease the  speaker noise.

[drphoto]

I have the original green board Stratos Monos (in fact there very ones in the web photos, as I took those pics) I found I could get hum issues if the input cables were not insert in 'just a certain way'. I found I could poke around on the cable and position it 'just so' and the hum would go away. I suspect there maybe in issue w/ the inputs, at least on mine. It doesn't seem to be specific to the cables, as I've tried a couple of different ones. I'm considering sending the amps back for a checkup. I've got a somewhat flaky power switch on one amp too. I'm not implying that there is a systemic issue with the inputs, but I seem to have something odd. The good thing is Odyssey stands behind it's products. Any mechano/electical device can have problems.

[pfradale]

With NO audio cabling attached to the amp, there is a faint, rapid, click-like buzz in the tweeter, almost like the noise from Triac light dimmers (which I have in the house, but they're all, in theory, turned off).  And there is a faint 120 Hz hum in the woofers.

I've that exact issue with my mono extremes.

[NekoAudio]

You'll want to talk to manufacturers of both your preamp and amp to see if there would be an undesirable side effects, but you may be able to eliminate/reduce the hum by lifting ground on only one of the channel interconnects. You'd need to purchase a ground lift adapter for this. Hopefully ground would be correctly referenced on both channels via one interconnect.

Another option that may help is to wire the chassis of the preamp and amp together. Some insulated copper wire between screws of the two chassis (screws that make contact with the internal chassis ground) will work. Make sure everything is unplugged when you do this, obviously.

Since, as Niteshade explained, ground isn't really a voltage value but instead just another path in the circuit, there is current flowing through the "ground bus" and where there's current there's voltage differentials between different points on that path.

[geowak]

I had many problems with hum and buzz with 3 Odyssey pieces.

I had the Stratos, Tempest and Candela. After countless experiments with cabling and troubleshooting, many conversations with Klaus, and a few shipments back and forth, I found no resolve and got rid of my Odyssey gear. It was a very frustrating experience.

IMHO I came to the conclusion they were using bad parts, or redesigned (re-engineered)? the Symphonic Line in a poor fashion.

I did not have any luck using the gear and eventually spent too much money on electronics that were not worth the price at all.

[FullRangeMan]

I get a low level hum or buzz from my speakers when my Stratos is on that I can't seem to eliminate. After much troubleshooting, here's the story:

With all audio and video devices unplugged from the wall and my pre, and with the Stratos plugged into a dedicated power line I get a hum when the amp is connected to my pre, even when a)the pre is unplugged and b)no sources are plugged into it. Removing ONE interconnect kills the hum in both speakers.

I normally run MIT AVT1 cables, but have tried Kimber (no grounded shield) and several others. No difference. I have tried with and without ground pin on the power cable.

The hum varies in volume and sometimes is not that noticeable but other times drives me baty. I have a redboard model.


Looking for ideas on taming this.

Hello Mschlack,
Iam impressed with your Stratos problem. Obviusly Stratos circuit is very musical because it have large freq range, is detailed and sensitive to interferences, this is not a defect, but a consequence of the good Stratos circuit design.

I will give you an idea that may or may not solve your problem. But it will no make any harm if well implemented. It is the following:
>> You must remove the Toroidal Transformers for an external metal box, you will need a longer cable between the transformer and the circuit of the amp, if you can not made it Odyssey may help you, I think. A good Toroidal transformer bed and top hat must have a thick layer of rubber or felt to reduce Transformer vibrations.

I do not like the usual Stereo and Monos amps cause the Transformer is always near and in the same chassis than the circuit amp, I prefer the two channels(Stereo) amp circuit in a chassis and the two power supplies in a separate box, as used in the very expensive integrated amp ASR Emitter.

Maybe Mr.Klaus may create a new STRATOS Stereo version with two outboard Transformers, this is a wonderful refinament.
Cheers, Gustavo