Hi DrS.
I'll give a full answer as best I can as this might be helpful for a number of people. If you wanted a "yo dood just buy a..." type of answer I'm afraid you have the wrong guy
. I'm more interested in giving you accurate information for discussion than just single sentence "guru" advice which "everybody knows" is true but which usually ends up in you spending money needlessly. Apologies if you get more than you bargained for but just skip the bits you don't want, but they are all ideas which may all help at some point.
One final thing, if you want more advice please read carefully and, if I have asked a question, please let me know the answer! It infuriates me when I ask clearly and specifically for more information and people just ignore the question and only comment on what I may have said or even something else completely. How do you expect to be helped if you do not feed back in the info which is needed? Anyway... First problem first!
Does this happen with no guitar and no cable plugged into the amp? Interference can be readily introduced via your cable or pickups, they are actually designed to do that job. Their magnetic field is very open to being affected by other surrounding fields as well as by metallic things like strings, and that also means changes in signal output I'm afraid. Pedals and the onboard supplies are also notoriously poor at rejecting this sort of crap, even the ultra expensive "boutique" versions which are often worse, so try without them in the signal path. If it still happens with the cable unplugged at the amp which shorts the input socket out, we know your guitar/pedals/cable are innocent and it is caused later in the chain possibly within the amp itself.
A serious thing to check is your home mains Earth/Ground integrity. If you have a poor ground connection anywhere in the chain or worse, a missing ground connection, then you could be in a very dangerous situation. Swap out your mains lead for another just to test for a broken earth lead inside. Also, wall mains sockets are usually connected via screwed terminals. The mains runs at 50/60Hz depending on whether you are on the good side or the bad side of the ball. Over time the constant mains buzz can actually loosen off those screws if they are not originally made securely enough. This is not a really common phenomenon but it does genuinely happen, ask any domestic electrician. The next piece of advice would let you know this.
Here is a relatively cheap tip which could just save your life and which I cannot get guitarists to take seriously. Always run your own personal equipment, amp + pedals + lights + bubble/smoke machine etc, from its own spur fed from your own dedicated extension/distribution strip plugged into the band line. Fit it with a RCD Safety Breaker as its mains plug, (here is an example:
(RCD Breaker), and a line tester permanently plugged into it in one output, (another example:
(Mains Condition Tester)). In use this poses no problem and will let you know if all three mains lines, Live Neutral and Earth, are connected securely and just as they should be. I first fitted this when I had a salutary experience at a school my band rehearsed in. One night for some reason I had to run my own line from a socket in the next room. I kept getting stinging buzzes from my mic on my lips and, knowing what this could mean, I metered the earth between the two rooms. They were out of step to the tune of 55V showing a serious fault somewhere. And that was at a school not an ancient run down venue! I immediately sourced and fitted both of the devices I linked to. Since then I have never had a problem as I am able to check the correctness of the mains line before I even switch on the amp, and when the amp goes on I know I am protected by the RCD trip. It's worth paying the money to get that if you are gigging in many different locations, some of them very old or a bit sleazy, (the best gigs
).
It would also help to know at what level of Gain you are playing. If you are on the Ultra channel with the Gain up high, even with low Master Volume, this is always going to be a potential problem due to the massively increased sensitivity of the preamp stages where the signal levels are low. And the guitar you use could also be weak in this area. Also, does the noise level change when you use any of the controls? Does the Gain increase it, or the Master Volume? That could tell us where in the chain the signal is sneaking its way in.
So first I would recommend you take the BS200 to a totally different location and check for your buzzing problem there. It sounds to me as though you might have something in the house, or even nearby in your area, which is injecting that buzzing onto your mains supply line or into the air around you for pickup. Many devices can do that, even relatively low powered ones if they are weak in this area. With the description you give of it, every X seconds, an example is a washing machine which rotates one way then the other with a pause in between could cause that if it is nearby electrically. If it does stop when you go to a distant location, (someone else's house or a rehearsal studio), then you know it is due to something in your own locale. That could be heavy industrial machinery in a nearby factory or workshop. It can be a problem, particularly for hifi nuts
, even if the factory or workshop is some distance away if you are both in a fairly remote location with a long feed to both your house and the site. If that is the problem then in extreme cases you can request to be put on a different phase of the mains, (it's usually three phase for industrial and single phase for domestic so you can be on any of those phases), to see if it improves. That might cost you so don't jump to that conclusion too soon, and you are not already aware of this in other electronics items so I wouldn't really expect this to be the issue.
As to your second question, are you playing with pedals at this time? Any digital pedals can be prone to this effect, it could be just digital hash. If you are using one of them then remove them from the signal chain completely, (i.e. unplug them from the signal chain and power supply and check again, don't just say to yourself "naaah, they are true bypass"). What power level have you selected on the back of the amp? I can't see clearly how this could really affect this issue but it may help to try playing with a different level, adjusting the MV to compensate, and see if the noise level changes too.
If the level of this is just "I can hear it if I get my ear up to the amp and play very gently but it isn't really audible when I stand in my usual playing position and play as normal," then I would say that it is probably as you would expect. Any circuitry which is activated when a signal is detected like a noise gate or compressor or which has digital sections in it like a digital chorus could cause this. It could be due to the pedal power supplies or the single multifeed types which are usually better and the more expensive makes are NOT necessarily better in any way than the Chinese cheapies, (one of which I use to drive a line of pedals each individually without any problem at all despite costing only £15 at the time). Another tip here. Consider running your pedal power supply from a battery for PSU noise free playing. I have a Makita power drill battery which I fitted with a USB phone charging cap which I butchered. (
(Makita Battery Cap)). I simply drilled it carefully and connected a DC socket direct to the battery terminals to give an additional 18V output to power my PSU. This runs my pedal supply and my whole board for days - literally! I have tested running it for four consecutive continuous 2hr gigs without recharging it in between and it still showed 3 bars out of 4 on the battery charge indicator. Battery power means no earth loops to worry about and no mains borne crap transferred through to the signal.
Let's be clear, ALL guitar amps have NOISE! Valves are pretty much terrible in this area and solid state designs can be noisy with poor design or inappropriate components. But, you can design a very quiet transistor circuit if you know what you are doing, (note I do not necessarily mean a usual guitar amp circuit here), as the noise contribution of the right transistor or opamp can be much lower than our valves. For example 12AX7 noise=8-12dB, 2SK209 JFET noise=0.9dB, NE5534 opamp noise=0.9dB. Valves do have advantages but so does solid state, which is one reason why H&K have a solid state buffer at the input of most of their amps. The fact that we are running our setup from a high impedance source is also a factor. High impedances are more susceptible to most noise injection processes.
Give us a little more specific info and try the simple tests first and let us know what you find. Hope there is something in this somewhere which helps.
Home
