Members Faldoe Posted March 12, 2008 Members Share Posted March 12, 2008 My BSIAB II and my booster lone pop when engaged. I consulted the DIY Stompbox fourm/ wiki page, I tried cleaning the jacks and what not but no luck. What can I do to get rid of that pop? I have resistors on the LEDs but still I got pops..... Link to comment Share on other sites More sharing options...
Members Faldoe Posted March 12, 2008 Author Members Share Posted March 12, 2008 help Link to comment Share on other sites More sharing options...
Members amp_surgeon Posted March 12, 2008 Members Share Posted March 12, 2008 Try disconnecting the LED and see if the pop goes away. If so, then put a larger resistor in series with the LED. It won't be as bright, but you only need to be able to tell it's on. It doesn't need to illuminate your pedalboard. If disconnecting the LED doesn't get rid of the pop, then you have other problems. Did you build from a kit, or did you get your own parts? Any chance one of your "upstream" pedals is putting some DC voltage onto the signal line? Try connecting the pedals direct: guitar -> pedal -> amp. If that stops the pop then one of your other pedals is guilty. Link to comment Share on other sites More sharing options...
Members Faldoe Posted March 12, 2008 Author Members Share Posted March 12, 2008 Cool I'll try both methods. In regards to the second thing the pedals are powered by a PP2+ - individual isolated power sources, so that shouldn't be the case right....??? Link to comment Share on other sites More sharing options...
Members cloudscapes Posted March 12, 2008 Members Share Posted March 12, 2008 google pulldown resistors. put one 1m resistor between ground and after the input capacitor, and one 1m resistor between the output and ground. might not get rid of it completelly but it's a good habit to take and generally helps pop is an issue we struggle with when making true bypass effects Link to comment Share on other sites More sharing options...
Members Faldoe Posted March 12, 2008 Author Members Share Posted March 12, 2008 thanks, love your avatar Link to comment Share on other sites More sharing options...
Members amp_surgeon Posted March 12, 2008 Members Share Posted March 12, 2008 Re. pulldown resistors - what cloudscapes says is generally good advice. Unfortunately, it won't help much with the BSIAB2 because it already has a 1M pulldown on the input, and doesn't really have an input capacitor, other than a parallel 250pf HF filter cap. The output comes off the rotor of a 100K output volume pot, so it's also already pulled down. Anyway, the purpose of the pulldown resistors is give DC voltages some place to go when the effect circuit is switched out. For example, the 2200pf cap in the pi-section RC filter (C14) might still have a small charge on it when you switch off the BSIAB2. Having a path to ground, in this case through the volume pot, gives it a chance to discharge. When I was talking about DC voltages, I wasn't referring to your power supplies. What you usually want coming out of a pedal is a low level AC signal - the sound from your guitar or an upstream pedal. Ideally, this AC signal should alternate equally above and below ground level, giving a 'centerline' of zero volts. If the centerline is above or below zero, then you have a DC offset. When you switch on an effect this sudden change in DC level can cause a spike in the output, which you hear from the amp as a pop. In an indirect way, having too much current drawn from the LED can cause a pop for the same reason. It causes a momentary sag in the +9V line, which cause a brief shift in the DC levels of the circuits, which results in a spike in the audio. Having smooth DC in the power, and no DC in the signal, is the key to keeping out switching pops. I don't know why they didn't see a need for an input coupling cap on the BSIAB2. If you wanted, you could try inserting one between the footswitch and the "I" pad on the PCB. They're using 0.022uf coupling caps in most of the rest of the circuit, so that would be a good value to try. Try the LED first, though. Adding a cap could change the tone slightly. Link to comment Share on other sites More sharing options...
Members Faldoe Posted March 12, 2008 Author Members Share Posted March 12, 2008 thanks Link to comment Share on other sites More sharing options...
Members Sardocasm Posted March 12, 2008 Members Share Posted March 12, 2008 Let's end this unhappiness over a nice... Link to comment Share on other sites More sharing options...
Members Clorox Posted March 12, 2008 Members Share Posted March 12, 2008 I thought the thread title said poops and now I'm sharing that with everyone. Carry on. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.