Author Topic: Tremolo like sound from NPN boost  (Read 11753 times)

nimdawg

Tremolo like sound from NPN boost
« on: April 29, 2009, 09:12:34 AM »
Hello,

I'm new here but I've built the NPN boost with the help of the Forum. It worked first time, no soldering problems and stuff though this is my first project. I'm using it with an adaptor on my pedalboard and noticed that besides giving me a boosted signal, it seems to make the volume waver. After listening to it for a while, it's like having a fast tremelo effect on.
What can be causing this (some bad grounding or contacts)? Has it got something to do with the 9v adaptor and if so, is there anything to stabilize this?
PLS help  ???

aron

Re: Tremolo like sound from NPN boost
« Reply #1 on: April 29, 2009, 12:21:31 PM »
I think it's the adapter. You want to use a regulated adapter like the One Spot.

The French connection

Re: Tremolo like sound from NPN boost
« Reply #2 on: April 29, 2009, 12:38:39 PM »
« Last Edit: April 29, 2009, 12:43:27 PM by The French connection »
I know, but the pedal i built does not boost...it just increases volume!
My picture files:
http://www.aronnelson.com/gallery/main.php/v/French+connection/
http://s193.photobucket.com/albums/z4/letournd/Pedal/

nimdawg

Re: Tremolo like sound from NPN boost
« Reply #3 on: April 30, 2009, 02:27:26 AM »
I think it's the adapter. You want to use a regulated adapter like the One Spot.

I'm using it with a 1 spot ans the enclosure is a hammond aluminum type.
I'll try check the wiring again.

The French connection

Re: Tremolo like sound from NPN boost
« Reply #4 on: April 30, 2009, 09:34:18 AM »
Is the ''tremoloop'' speed change when you turn the volume pot? I've got this problem too with the boost in a plastic box; move it to a metal one and the ''tremolo thing'' stops. So i've concluded that was the box shielding. Try disconnecting your LED for the kicks? ???

Dan
I know, but the pedal i built does not boost...it just increases volume!
My picture files:
http://www.aronnelson.com/gallery/main.php/v/French+connection/
http://s193.photobucket.com/albums/z4/letournd/Pedal/

earthtonesaudio

Re: Tremolo like sound from NPN boost
« Reply #5 on: April 30, 2009, 10:15:48 AM »
More info on the problem might help.   

I'd recommend the normal "debugging" procedure, then if (and ONLY if) that doesn't find the problem, answer this question:

Does the "tremolo" sound stop at max boost?
If yes: replace or temporarily remove the bootstrap capacitor.  A leaky cap might cause oscillation and bias troubles.
If no: maybe a big BIG cap across the supply rails, as close to the circuit as possible.  If your power/ground lines are long, that can sometimes cause a problem.

aron

Re: Tremolo like sound from NPN boost
« Reply #6 on: April 30, 2009, 06:18:12 PM »
What if you run it off of a battery? By itself?

nimdawg

Re: Tremolo like sound from NPN boost
« Reply #7 on: May 02, 2009, 12:32:02 PM »
Thanks for all the advice!

I rewired the DC jack and added some insulation between the circuit and the DC jack. I also rewired the ground connections between the input/output jacks.
After this, the tremelo sound disappeared - problem solved! Can't put my finger on what it was but I suspect the DC jack was touchng something and possibly affected the supply voltage to the circuit (maybe causing a flactuating voltage which caused the tremelo).

Anyway, thanks for everything - a great build which I managed to put in a Hammond 1590A
See picture:
2009_01_05 016.jpg

nimdawg

Re: Tremolo like sound from NPN boost
« Reply #8 on: May 02, 2009, 01:24:06 PM »
More pictures

Inside the NPN boost (tight fit in Hammond 1590A)



Circuit on Veroboard - small and compact


Small footprint of NPN miniboost


On my pedalboard sitting next to an OCD and ready for action

Voodoo Blues

Re: Tremolo like sound from NPN boost
« Reply #9 on: July 25, 2009, 12:56:03 AM »
I'd recommend the normal "debugging" procedure

What is the normal debugging procedure?
Who put a fog machine in my pedal?

earthtonesaudio


Ben N

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Re: Tremolo like sound from NPN boost
« Reply #11 on: September 09, 2009, 09:37:24 AM »
I just want to add my recent observation about this phenomenon. I built the NPN boost in an unshielded plastic enclosure, and found that it had the tremolo effect depending on location/proximity to various other stuff, like transformers, etc. So I shielded the enclosure with foil and tested, and the problem was gone--or so I thought.

When I put it into my pedalboard, the tremolo was back. WTF? I left it for a while, but I just unpacked my pedals after a move and reloaded my board, and lo and behold, the problem has to do with my Echo Park. When the booster takes its signal from the EP, it tremolos. Interestingly, whether the EP is on or bypassed makes no difference, and the speed of the tremolo is constant and unaffected by the repeat setting. When I switch them (which I did not want to do because I don't want to overload the EP) so the booster feeds the EP, the problem is gone. I did not change the location of the booster or its power connection (the whole board is fed by a single 1-Spot)--the only difference is the EP. The good news is it works, and I haven't noticed any obnoxious distortion from the EP input being saturated.

Anybody have a similar experience, or an explanation?

The French connection

Re: Tremolo like sound from NPN boost
« Reply #12 on: September 09, 2009, 10:01:13 AM »
I just want to add my recent observation about this phenomenon. I built the NPN boost in an unshielded plastic enclosure, and found that it had the tremolo effect depending on location/proximity to various other stuff, like transformers, etc. So I shielded the enclosure with foil and tested, and the problem was gone--or so I thought.

When I put it into my pedalboard, the tremolo was back. WTF? I left it for a while, but I just unpacked my pedals after a move and reloaded my board, and lo and behold, the problem has to do with my Echo Park. When the booster takes its signal from the EP, it tremolos. Interestingly, whether the EP is on or bypassed makes no difference, and the speed of the tremolo is constant and unaffected by the repeat setting. When I switch them (which I did not want to do because I don't want to overload the EP) so the booster feeds the EP, the problem is gone. I did not change the location of the booster or its power connection (the whole board is fed by a single 1-Spot)--the only difference is the EP. The good news is it works, and I haven't noticed any obnoxious distortion from the EP input being saturated.

Anybody have a similar experience, or an explanation?

Got the same problem...or almost. Weird!  ???

http://www.diystompboxes.com/smfforum/index.php?topic=78029.msg641881#msg641881

http://www.diystompboxes.com/smfforum/index.php?topic=1056.msg637664#msg637664
I know, but the pedal i built does not boost...it just increases volume!
My picture files:
http://www.aronnelson.com/gallery/main.php/v/French+connection/
http://s193.photobucket.com/albums/z4/letournd/Pedal/

Ben N

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  • Posts: 4280
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  • Ben N. - really! Now Israel, once Baltimore
Re: Tremolo like sound from NPN boost
« Reply #13 on: September 09, 2009, 01:02:54 PM »
Yeah, Dan, I remember your other posts. Mine is at the end of my fx chain--just before the Echo Park. So it is ok following some other effects, just not all.

aron

Re: Tremolo like sound from NPN boost
« Reply #14 on: September 09, 2009, 05:38:06 PM »
Is your Echo Park and Booster on different power supplies?

Ben N

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Re: Tremolo like sound from NPN boost
« Reply #15 on: September 10, 2009, 12:33:46 AM »
Nope--everything is on the 1-Spot. I haven't tried it with separate supplies, although I guess I should (for the sake of science).

earthtonesaudio

Re: Tremolo like sound from NPN boost
« Reply #16 on: September 10, 2009, 10:24:42 AM »
The fact that it was "cured" earlier by re-flowing the solder joints, plus the recent move, makes me wonder whether it's still a physical connection problem.  It might have been bumped around during the move enough to loosen whatever connection was problematic before.


If it turns out to be a purely electronic problem, I'm betting some resistance in series with the input would cure it.  Maybe even a different length of cable between the Echo Park and the booster.


But I'm still curious whether you can change the rate/depth or any parameter of the tremolo effect by adjusting the boost control.

aron

Re: Tremolo like sound from NPN boost
« Reply #17 on: September 10, 2009, 06:22:58 PM »
Ben,

I had numerous problems with the Echo Park and the One Spot. Now I run it alone with a real Line 6 adapter and everything's fine.