Hi everyone!
I'm looking for a schematic for an easy to build hum eliminator. Ebtech makes one and i've noticed ART has come out with one. Whats the technology?
Perhaps a transformer of some kind?
isolation transformers.
should be some good info if you search around here a bit.
ta-dah! (http://www.jeffrowland.com/tectalk1.htm)
hey, looking there I found this link
http://www.jensen-transformers.com/as/as032.pdf
Is this a good testing for stompboxes and homebrew amps?
Hum can come from a lot of places, and transformers are only the solution to some of those sources. Sometimes, hum is addressed by ridiculously steep 60hz notch filters.
The isolator trick shown in the "Hum Free Splitter" at GEO works nicely with one output as well. It uses an opamp to drive a cheap transformer to get accurate frequency response across the range of 62Hz to 20kHz out of a $2.75 Mouser transformer.
It's a a way to not use $50 Jensen transformers, although Jensen makes great transformers if you have the $.
WOW! Thanks guys!
I did a search here and only found the hum canceler/splitter. I may investigate that. I had a quiet effects rack until I added one last unit. Now I have I buzz. Seems to be in the higher freq's. It goes away when I unplug one of the vintage tube amps from the last stereo processor. I will experiment with isolating the last unit from the rack. Haven't tried that yet. Thought I might try the Ebtech "hum eliminator" or better yet,build one.I was looking for schematics,if anyone can help.
Could it be the power supply?
The jensen link doesn't seem to work. :(
The jensen link doesn't seem to work. :(
yes, power supply ripple may cause hum in audio circuits.
I've traced the noise to a ground loop from the rack rails. I will isolate the offending unit. Thanks for your help!
QuoteI've traced the noise to a ground loop from the rack rails. I will isolate the offending unit. Thanks for your help!
Lonnie would be proud ;)...
Sorry, wrong forum :mrgreen:!
???
6 years after any of you guys know how to build one of this? schem, pictures, anything :icon_question:
cheers.
http://www.beavisaudio.com/Projects/Huminator/
Shabam.
Quote from: Craiz on April 21, 2012, 01:58:02 PM
http://www.beavisaudio.com/Projects/Huminator/
Shabam.
I already know that proyect, but if you notice the hum eliminator is not another filter phase for a power sypply it worck with 1/4" plugs, so you can connect it to your chain of pedal or maybe in the conection between cabinet and head.
Like Mark Hammer said, hum has many causes and there are many devices that address them. The Ebtech Hum Exterminator plugs into the mains socket (I guess it filters and/or isolates power). Others filter the audio signal or isolate devices through transformers, and as such need to be in the signal chain.
QuoteWhats the technology?
- Ground loop breakers (including isolation transformers)
- Extra filtering for power supplies
- high Q notch filter @ hum frequency
Pick your poison. Only the last one can be fitted to the signal path with conventional methods and instead of cause of the hum will remove hum that is already in the signal.
QuoteI already know that proyect, but if you notice the hum eliminator is not another filter phase for a power sypply it worck with 1/4" plugs, so you can connect it to your chain of pedal or maybe in the conection between cabinet and head.
You are wrong. Check again.
I think we are focussing a bit too much on hum from the wall. I do most of my pedal testing using a battery-powered amp, and use batteries for the pedals. So there shouldn't be any hum, right?
Wrong. My office/workshop has fluorescent fixtures, and most of my guitars use non humbucking pickups.
I can assure you that even if I use the very best power supply designed by RG and his hotsy-totsy EE buddies, my guitar WILL hum when I'm sitting under those lights.
A true hum eliminator is one that is designed to take out 60hz (orwhatever the wall AC is where you live) signal and its byproducts, no matter where they come from or where they show up in the signal chain.
by the way I'm talkin about this thing
Hum Eliminator http://cachepe.zzounds.com/media/quality,85/brand,zzounds/he-2_left_bottom-45f2c7549b6a89413c0fa68748190ac9.jpg
and this
hum X http://www.long-mcquade.com/files/5565/lg_humx.jpg
seems like the conversation is going two different ways... hum from ground loops and just hum at your pickups.
just thought i'd throw this one into the mix for fun too:
http://www.muzique.com/schem/silencer.jpg (http://www.muzique.com/schem/silencer.jpg)
http://freecircuitdiagram.com/wp-content/uploads/2008/08/hum_filter.gif
Quote from: pantufla on April 21, 2012, 05:38:02 PM
Quote from: Craiz on April 21, 2012, 01:58:02 PM
http://www.beavisaudio.com/Projects/Huminator/
Shabam.
I already know that proyect, but if you notice the hum eliminator is not another filter phase for a power sypply it worck with 1/4" plugs, so you can connect it to your chain of pedal or maybe in the conection between cabinet and head.
Quote from: pantufla on April 23, 2012, 07:42:40 AM
by the way I'm talkin about this thing
Hum Eliminator http://cachepe.zzounds.com/media/quality,85/brand,zzounds/he-2_left_bottom-45f2c7549b6a89413c0fa68748190ac9.jpg
I have one of those. It is a passive ground loop eliminator that uses isolation transformers. There are two variations on that theme at GEO - but they are active designs:
http://www.geofex.com/FX_images/splitter.gif
http://www.geofex.com/FX_images/spltr2.gif
These will get rid of ground loop hum only. They won't help you with mains hum, cheap power supply hum, single-coil pickup hum, fluorescent light hum, or any other type of hum including Windsor Hum (http://www.cbc.ca/news/canada/toronto/story/2012/04/21/windsor-hum-dechert.html).
Early or mid 80´s Elektor magazine and "300 circuits" series books had such narrow notch filter, was done with op amps and it had two filters in series, one for 50 Hz and second for 100 Hz (few guitar amps go down to 50 hz)
There is a problem with filtering hum out. 50H, 60Hz and their first few harmonics fall close to musical notes.
For instance: 60Hz is below the low E of a guitar at 82.4Hz. If you want to suppress the 60Hz by 40db (1/100 the power and about 1/4 the volume) then you need to have a filter that's not noticeably losing signal at 82Hz and is 40db down half an octave a way. That's a (roughly, not doing the math precisely) 80db/octave filter, which is INSANELY difficult to do by analog means. Cauer and elliptical filters can be done to put a suppression notch in the stop band right over the desired frequency, but just the necessary precision of parts will make this very, very difficult to do reliably. The slopes on the sides of a suppression notch are necessarily steep, so if you miss the exact frequency just a ...little... bit, it not only doesn't remove the hum, it removes something else that you may want.
Worse, 120 Hz power supply ripple and fluorescent light bulb buzz is only 3.46Hz from Bb at 116.54Hz and B at 123.47Hz. Removing 120Hz with a notch and leaving both Bb and B alone is essentially impossible by analog means. It ain't easy in digital. CBS tried to do a copy protection scheme with very tight notches in the recorded material which would be detected as "protected". Seems it was obscenely audible, and they finally gave up before perverting the recorded music world even more than it is already.
Hum is in some ways like Ebola virus: it is by far better to stop it from getting in to start with than trying to eradicate it once it's already there.