R
RFR
Well-known member
Yup, bad filter caps in an amp will produce some noise.
Electric guitar hum and buzz, how did the engineers using tape manage to avoid it?
rob aylestone
Moderator
I have a Fender jazz bass. Sometimes it was silent, some places it hummed like hell! Same amp, same lead, same settings so just susceptible to mains frequency interference. I eventually fitted new pickups and while doing it, I covered the cavities with copper foil and also wrapped the unscreened cables from the pickups with it. It's now silent, everywhere!
E
ecc83
Well-known member
Does the thech' have the secret formula for Strad varnish Al?
Dave.
Dave.
R
RFR
Well-known member
witzendoz
Senior Member
spantini
COO of me, inc.
I thought of this thread earlier this evening - our local public radio station whipped out Led Zeppelin I.. the whole album.
I say album because I could hear the needle, but no buzz or hum.
There is a lot of empty space in that album, music-wise, and it was not filled with noise. How'd they do that?
I say album because I could hear the needle, but no buzz or hum.
There is a lot of empty space in that album, music-wise, and it was not filled with noise. How'd they do that?
R
RFR
Well-known member
Don't know if it was mentioned earlier, but back in the day, there was a lot less 'electrical pollution'. You could record sonewhere and all you had was some juice from the wall. At worst you might have to unplug the fridge to keep the compressor from kicking on.
Now it's everywhere. (Noise)
But there were cases when a Strat and a Marshall would pickup an AM radio broadcast. If I remember correctly, Hendrix had that going on at Woodstock.
But overall we're in a much noisier electrical environment today.
Now it's everywhere. (Noise)
But there were cases when a Strat and a Marshall would pickup an AM radio broadcast. If I remember correctly, Hendrix had that going on at Woodstock.
But overall we're in a much noisier electrical environment today.
witzendoz
Senior Member
miroslav
Cosmic Cowboy
Then you can also have some fresh eggs every day.
Here's some more info on audio interference.
Resolving Interference Problems || Audio-Technica
E
ecc83
Well-known member
Cheeky! What I mean is Alan, taking a power traff out, heating it up and tightening the frame bolts PLUS a coat of varnish CAN often silence one that has a mechanical buzz. But, the varnish is rarely needed and in any case you have to be very careful about solvents in electronics. Some can compromise insulation and only a very few meet flammability criteria.
Dave.
witzendoz
Senior Member
I don't know what he does LOL, it was written on the repair report, he does know what he is doing and the transformer stopped making noise.
Alan.
Alan.
E
ecc83
Well-known member
Right'o, all cool. We had a problem yonks ago with a component in the first colour TVs screaming at 15,625 Hz and the only "gunge" that was safety approved was white PVA glue!
The part was called a "Transductor" clever little bugger that made the horizontal and vertical scan currents "interfere" with each other.
Mind you, it was usually only the Lady of the House that was bovvered!
Dave.
rob aylestone
Moderator
That's the tricky bit - there is so much use nowadays of using the mains supply to control equipment, or pass the internet, or have a baby alarm monitor etc etc that todays's mains power cables provide much of the crud we then fail to get rid of. I'm not sure where you'd get isolated power from at any decent amount of current spec. Transformers are not cheap for large ones, and isolated PSUs for computer powering with battery backup are very limited in capacity. In so many events and stage shows, the audio people demand in the contract - clean power, separated from the dimmer power. Sensible requirement, but as all that is different is that the distribution point feeds dimmers in one direction and sound in the other - As mains power is AC, and interference local to the dimmer can just as easily go back and infect the 'clean' supply. I think nowadays clean power is simply impossible. superimposition of HF and above data streams onto the mains will pass through a transformer unless it's designed with a substantial choke function. They do get reduced going through transformers if the devices are big and chunky, but using a scope to look at AC mains shows that there are far more things going on, other than 50/60Hz sine waves.
E
ecc83
Well-known member
Rob, I cannot speak about big events with kWs of dimmed lighting (except the stuff SHOULD meet EU EM regulations!) but as far as "studio", especially "projjy studio" supplies are concerned there should not be a problem.
IMO audio gear should be made with adequate mains filtering built in. At the very least a 100nF X type cap across the incoming. If a 50Hz transformer is used (especially if it has, Oh! Luxury! An interwinding shield) that will stop as good deal of mains borne crap. Trouble is of course, SO much kit uses SMPSUs and these are not always built to stop mains ***T as well as a good lump of iron and copper does. Can be done. Many don't. Then, you can get switching spikes from Silicon rectifiers and mains get the blame because the bean counters baulked at the cost of 4 1nF ceramics.
The isolator transformer route is one answer IF you have a problem but we are talking lethal voltages here and any such devices must only be installed by a competent sparks who understands the situation. In short, EVERY piece of studio gear must be powered from the iso-traff and I don't know the regs but I would assume the secondary would need its own breaker box and RCD?
"Balanced" mains supplies have been mentioned here before and they do promise very low noise levels but have serious safety implications in a studio where kit comes and goes and could be opened and serviced by persons not fully informed of the mains conditions. Not QUITE so bad when it is only 50ish volts about earth!
Dave.
IMO audio gear should be made with adequate mains filtering built in. At the very least a 100nF X type cap across the incoming. If a 50Hz transformer is used (especially if it has, Oh! Luxury! An interwinding shield) that will stop as good deal of mains borne crap. Trouble is of course, SO much kit uses SMPSUs and these are not always built to stop mains ***T as well as a good lump of iron and copper does. Can be done. Many don't. Then, you can get switching spikes from Silicon rectifiers and mains get the blame because the bean counters baulked at the cost of 4 1nF ceramics.
The isolator transformer route is one answer IF you have a problem but we are talking lethal voltages here and any such devices must only be installed by a competent sparks who understands the situation. In short, EVERY piece of studio gear must be powered from the iso-traff and I don't know the regs but I would assume the secondary would need its own breaker box and RCD?
"Balanced" mains supplies have been mentioned here before and they do promise very low noise levels but have serious safety implications in a studio where kit comes and goes and could be opened and serviced by persons not fully informed of the mains conditions. Not QUITE so bad when it is only 50ish volts about earth!
Dave.
rob aylestone
Moderator
I had some real issues a month back - a batch of dodgy LED lights GU50's that I'd stuck in the studio - and they caused all sorts of problems until I worked out what it was - a nasty buzz, and as I never use the studio with the lights out, it didn't click why it was suddenly there. Re: the switch mode PSUs - the one on my external hard drive was simply awful, and the USB took the interference back to the computer - where it spread to the interface!
Grrrrr
Grrrrr
witzendoz
Senior Member
I did replace the Energy saving globes around the studio with halogen globes, this did reduce the noise for guitars with single pole pickups. My control room developed a clicking / crackling sound in the monitors one day, eventually after I had given up to go home and turned everything off I noticed our security Fluorescent tube over the front door had began to flash on and off during the day (I leave it on 24hours). Switched it off went back inside and fired up the control room again no noise. Replaced the tube all good. Bloody Fluorescent tube was not even on the control room circuit 
Just shows the things that can act up.
Alan
Just shows the things that can act up.
Alan
miroslav
Cosmic Cowboy
I did replace the Energy saving globes around the studio with halogen globes, this did reduce the noise for guitars with single pole pickups. My control room developed a clicking / crackling sound in the monitors one day, eventually after I had given up to go home and turned everything off I noticed our security Fluorescent tube over the front door had began to flash on and off during the day (I leave it on 24hours). Switched it off went back inside and fired up the control room again no noise. Replaced the tube all good. Bloody Fluorescent tube was not even on the control room circuit
Just shows the things that can act up.
Alan
About 10 years back, maybe even a bit longer...before the new light bulb rules went into effect here in the USA, I thought I would try some low-wattage, energy saving bulbs...the ones that fit in a normal incandescent bulb socket, where they had some sort of small transformer circuit built into the base of each bulb.
I was just going to used them for my outdoor porch/deck/door lights, since I would just turn those on overnight, and I figured the energy savings would help with the electric bill.
Well...they worked OK...and everything seemed to be fine.
I had not done any work in my studio for several days following, so finally one evening I went into the studio, turned on my gear...and there was this weird buzz coming from the studio monitors.
*sigh*....I thought something was going bad in one of my audio pieces...so OK, let's start the elimination process.
After a couple of hours...I gave up...couldn't narrow it down to anything in the studio...so I figured I would let it ride and maybe it was just a one time fluke...something weird with the electric supply...etc.
Next day I went in during the afternoon...no buzz.
I think I then took a dinner break...came back...there's that $#@!*& buzz again!
So...for the next few days, this went on, and I kept looking for the cause, trying this and that, always assuming it was my gear...or the electric...
...and then a light bulb went on in my head...
...and I put 2+2 together and realized that it was those stupid "energy saver" bulbs.Went and removed all of them and put back normal incandescing bulbs...no more buzzing.
Those bulbs weren't even on the same line...I have dedicated lines to the studio...and they still caused noise.
I don't use any energy saver bulbs that have built in transformers or whatever they use. I have fluorescent bulbs in my shed, but they only go on when I'm in the shed...so they don't cause any problems.
witzendoz
Senior Member
There was a studio in the city once that had a strange clicking sound that appeared every afternoon at around 4pm and stopped at 6pm, they tried everything to fix it. One day they realised it was the flashing no left turn signal on the traffic lights on the intersection outside the studio 
E
ecc83
Well-known member
Yes, there are sources of noise that we did not have 40yrs ago but there is a big difference today in the education level of studio personnel.
Things such as thermostat clicks (thumps bangs!) were tackled AT SOURCE. That is WE made up mans filters for the offending gear and fitted it close to the fridge etc. For a noisy lighting circuit we would have put filters in the feeds to the fittings and possibly at the consumer unit (fuse box for our colonial brothers)
The actual equipment was modified, you could not rely on manufctrs to fit RFI filters. The coming of the Silicon transistor cause all sorts of problems for me living as I do not many clicks as the RF carrier flies, from both Rugby and Daventry!
Most "hobby" studio people today cannot make up a simple guitar cable leave alone diagnose an RFI problem and fit the filters.
Dave.
Things such as thermostat clicks (thumps bangs!) were tackled AT SOURCE. That is WE made up mans filters for the offending gear and fitted it close to the fridge etc. For a noisy lighting circuit we would have put filters in the feeds to the fittings and possibly at the consumer unit (fuse box for our colonial brothers)
The actual equipment was modified, you could not rely on manufctrs to fit RFI filters. The coming of the Silicon transistor cause all sorts of problems for me living as I do not many clicks as the RF carrier flies, from both Rugby and Daventry!
Most "hobby" studio people today cannot make up a simple guitar cable leave alone diagnose an RFI problem and fit the filters.
Dave.