[chadh]

I have a little problem, and I don't know exactly what it is.  I was hoping that somebody might have some insight.

A few months ago, I was happily listening to music using a stock SB2, a 6sn7 tubed preamp, Channel Islands VMB1 chip-amp monos and some VSA VR1 monitors.  Things sounded nice, and I hoped for even better things once my SB2 had been modded by Wayne at Bolder Cables.

I had the SB2 modded while I moved house, and eventually managed to set up the system with the newly modded SB2.  In the process I broke a spade off on of my speaker cables.  So as a temporary measure, I hooked up a crappy pair of monster speaker cables.

I discovered a problem:  every now and again, I'd get a nasty amount of static/noise coming through the speakers.

I contacted Wayne at Bolder Cables, and he suggested it may have been a problem with the SB2 display putting out some kind of interference.  There's a history of SBs doing this, but the interference tends to be close to the noise floor, concenrated in the right channel, and tends to disappear when one dims the display.  None of these things were true of what I was experiencing.  However, some of the noise generated seemed to be synchronised with the pulsing of the SB2 display.

Well, Wayne recommended that I send the SB2 back for some additional ERS paper treatment around the display.  Before I did this, I wanted to get another SB to play music for me. But in the meantime, I took the pre-amp out of the system.  This seemed to help, initially.  But the static was still there.  Sometimes.

Once I secured a stock SB2 to serve music for me, I sent the modded SB2 off to Wayne.  The stock SB2 slipped into the system, without the pre-amp, and seemed to work well.  But yesterday I added the pre-amp back in and had terrible static problems again. This made me suspect the pre-amp was at fault.

This morning, I swapped tubes in the pre-amp, and things were much better.  This made me think that the pre-amp was not at fault, but perhaps something was wrong with the tubes.  But by the afternoon, the static was back (although not particulary badly).

So now I don't know what's to blame.

1.  It's certainly not something peculiar to the modded SB2, since I get the same problems with a stock SB2.

2.  It's probably not the tubes themselves as the problems seem to resurface with different tubes.  But maybe the tubes become particularly sensivtive to interference from something like the SB2 display.

3.  Maybe it's the pre-amp.  But why would things have worked without a probelm prior to my move, but suddenly generate problems?

4.  Maybe it's the speaker cables that I'm using (just until Wayne sends back repaired speaker cable with the ERS'ed SB2).

Any suggestions?  I worry especially that it's a problem with the tubed pre-amp,since this is my first peice of tubed equipment, and I don't really know what can go wrong (e.g. what a bad tube sounds like).  I'm hoping, though, that it's all to do with the speaker cable.

Chad

[DSK]

Hi Chad,
This is weird but I have the reverse situation to you  .... kind of.

I bought my SB2 online and had it shipped directly to Wayne for the analog & digital mods. I also bought the Deluxe PS. When they arrived here (Australia), I initially ran the SB2 directly into my solid state power amp (AKSA 100 N+) and subwoofer (using RCA Y-adaptors). Every now and again I would get a low volume static noise from the right channel, kind of like when you get momentary interference on a radio station. It was only low volume and each burst only lasted from half a second to 2 seconds so I didn't worry about it. Six months later, I put my tube hybrid pre-amp (AKSA GK-1) back into the system and used it to drive the power amp and subwoofer. I haven't heard the static since, not even once. That was several months ago and no other changes were made to the system. Also, the sonic performance improved with the pre-amp back in the system. Better dynamics, palpability and the noise floor seemed to have dropped. My SB2 has been wireless (to a Netgear WPN824 RangeMax wireless router) the whole time.

So, my belief is that the problem does originate at the SB2.

[jermmd]

Chad,

I never had a problem of any kind with that SB2; definitely no static using the analog out into my receiver. I think it's highly unlikely to be a problem with the SB2. Have you tried other sources with the preamp? Is there a loose connection somewhere?

[chadh]

The slim devices board has a thread discussing the effects of interference from the display.  It happens on some units and not on others, and seems to correspond to the experience of DSK.  The effect would usually be mitigated by use of a pre-amp as the pre-amp will allow you to operate the SB closer to its maximum volume level.  The interference is invariant to the SB volume level, so this means that the signal-to-noise ratio will be low.  When you attenuate using the pre-amp volume control, this helps to hide the noise.

The thing is, this isn't my experience at all.  But the fact that the noise I get seems synchronised with the way the display pulses makes me think that my experience is at least related to this problem.  It's as though I've got the same low level noise that comes from the display interference, but something else in my system is amplifying it.  And I'm just not sufficiently clued-in to know what that might be.

A loose connection?  All of my cables seem securely connected.  But what if the terminations on my speaker cable were bad?  Might that generate static?  I keep wondering about the speaker cables because they seem to be the only thing that was not in the system before I moved (when I had none of these problems), but have been in the system ever since (while I've had these problems).  Since moving, the SB2s have rotated in the system, and the pre-amp has been in and out.  The amps have been constant, but they were also there prior to the move (along with the ICs and power cords).  The only other variable that is new since the move is the mains power supply.  I might be in a much dirtier distribution area than previously.

Chad

[DSK]

Chad, I hadn't seen that thread bt what you say makes sense. With the SB2 direct to amp, the SB volume was always set between about 10 to 20. With the pre-amp in place, I have been setting its volume as close as possible to the full 40, with the pre-amp volume control (a top notch TKD stepped attenuator) at about 1 o'clock. I had put the lowered noise floor (with pre-amp in system) down to this factor.

You don't say what sort of terminations are on the Monster cable. If the terminations are secure, or you are using bare ends, it seems unlikely that the cable would cause the problem you are having ... unless there is a partial break somewhere along the length of cable. I'm wondering if there could be a weakened connection (solder joint) at one of the connections (eg. one of the RCA's or binding posts inside the amp)?

[jermmd]

Try some zip chord for speaker cable and see if the problem goes away.

[sts9fan]

I have recently started getting static through my tweeters from my SB3. I have changed nothing! I discovered it the other day and since I only have two componets it was pretty easy to find the source. It comes through even when the SB3 is just displaying the time and date. I have an SB2 that I am going to try and switch in tonight and see if that changes anything.

[avta]

chadh:
Not sure if this is relevant for you but I had a static problem when I began using my new Nuforce Ref 9's. I assumed, incorrectly, that it was the amps. since they are known to generate interference in some systems. Nevertheless, I went through my usual steps in trying to diagnose problems. I first switched the preamp inputs and noted that the static, which had been in only one speaker, switched to the other speaker. I suspected that one channel of the pre ( a Norh aca 2b ) was the culprit. I reached down and touched one of the two tubes and heard a loud crackle..then the static disappeared. I've not heard it since.
Guy

[chadh]

Terminations on the monster cable are solderless ratshack banana plugs on one end, and something similar in the other.  I will try to swap the cables out as soon as possible:  hopefully that will make the difference.

But, if it is the speaker cables, I really don't know why this effect should be more noticeable with the pre-amp in the system.

This is very confusing for me...I'll update you when I think it's fixed.

Chad

[avahifi]

Lets simplify to find the source of your problem.

First of all is a two channel identical problem or a one channel problem?  All sources or just one source?  Does the noise level vary with the volume control setting?

Let me know and we can go from there.

Frank Van Alstine

[avahifi]

And, oh yes, does the problem occur only when you are playing music, or does it also or only occur when the system is on but playing nothing?

Frank

[chadh]

Lets simplify to find the source of your problem.

First of all is a two channel identical problem or a one channel problem?  All sources or just one source?  Does the noise level vary with the volume control setting?

Let me know and we can go from there.

Frank Van Alstine

Thanks Frank.  Let's see...

This does not seem to be a two channel identical problem.  Nor is it a single channel problem.  I seem to get different types of noise out of the two channels at different times.  For example, the SB2 display tends to pulse, and I'll get a synchronised pulsing sound through one of the speakers (sort of like helicopter blades whirring).  Meanwhile, I'll have some completely independent crackle/static coming through the other channel.

I only have one source, so I can't tell if it's all sources.  I've had this problem with two different squeezeboxes hooked up.  But I haven't tried anything else.  That would be a sensible thing to do, I guess...I could at least hook up a portable CD player.

The noise doesn't vary with changes in the squeezebox digital volume control.  But it does vary with changes in the pre-amp volume control.  So I can get rid of most (but not all) of the noise by turning up the sqeezebox volume and turning down the volume of the pre-amp. 

When the system is on but playing nothing, I get some of the noise.  The helicopter blade beating that is synchronised with the squeezebox display pulsing is often audible.  And if I go and mess with the squeezebox volume control while no music is playing, I certainly get noise through the speakers.

I've also swapped interconnects and speaker cables around to try to whittle down options.  The conclusion I came to was that at least some of the problem is associated with the squeezebox.  That helicopter blade sound, for example, would always be associated with a given squeezebox channel.

I'm an electronics ignoramus.  But if I had to guess what was happening, I'd think that the squeezebox (all squeezeboxes?) put out some small amount of noise which is usually inaudible.  But something else is messed up in my system that amplifies this noise.  I have no idea...maybe the tubes in my pre-amp resonate in sympathy with the squeezebox noise or something.  I worry about the pre-amp, because the problem is so much more pronounced when the pre-amp is in place.

Chad

[Vinnie R.]

Chad,

If you can, I recommend you try connecting your SB to an Ethernet cable instead of wirelessly ("connect to wired network" when you turn on your SB to set this up).

If you connect with an Ethernet cabel to your router, you just need a regular cable, but if you connect directly to your computers Ethernet jack, you need a "nul modem cable" (also called a "crossover cable"). 

I suspect you are picking up wireless noise with your SB.  Running with an Ethernet cable instead of wirelessly shuts off the wireless section in the SB.   

Hope this helps,

Vinnie

[chadh]

Vinnie,

Thanks for the suggestion.  I shall load slimserver onto my laptop and check it out this evening.  I'll be disappointed if this is the problem, though...the computer I use as a server is in the basement, and the SB2 is not.

Chad

[Vinnie R.]

Vinnie,

Thanks for the suggestion.  I shall load slimserver onto my laptop and check it out this evening.  I'll be disappointed if this is the problem, though...the computer I use as a server is in the basement, and the SB2 is not.

Chad

Ok...if you are going to connect your SB2 directly to your laptop, make sure you use a crossover Ethernet cable.   You can buy one at your local Best Buy, Staples, or other store that sells computers and routers...

Based on the details you mentioned about your problem, I'd say it is wireless noise that is being picked up and demodulated down into baseband noise that you are hearing.   

Good luck,

Vinnie

[chadh]

Thanks again Vinnie, especially for your patience.  I wonder how long it would have taken for me to understand that you had already told me to use a crossover cable in this situation.

Chad

[byteme]

I had a similar issue recently - similar setup too!  Tubed preamp, RWA SB3 running wireless from the server in my office upstairs.  Had a very odd but not constant or consistent buzzing sound only in the right channel.  For weeks I couldn't find it, I swapped tubes, cables, bypassed the preamp, everything I could think of.  Turns out the dust cap on the 8545 driver in my right speaker was coming unglued and vibrating against the cone.  I noticed it on one of my many trips behind the speaker to the back of the cabinet, a little flash of the voice coil caught my eye.  I pulled the dust cover off the rest of the way and the problem was solved.

It could be many things!  Hopefully it's not wireless noise - that would really kill a big part of the functionality of the SB.

[avahifi]

Next step, run the preamp and amp with no inputs connected to the preamp, just preamp to amp to speakers.

Any noise now?  Turn on the squeezebox, not connected to the preamp, but near it.  Any noise now?

I suspect from your description that the noise is originating in the squeezebox. Certainly if the amp and preamp are noise free with the squeezebox off and disconnected from the system you have found Mr Mustard with the rope in the kitchen.

Regards,

Frank Van Alstine