Effect Chain Hum/Feedback

[Insomnia_Junkie]

I have gone through the topic archives but haven't found anything to help me out. I cant quite seem to get the hum/feedback out of my effects chain. Whenever I activate my Sansamp Programmable Bass Driver DI I get a steady, loud hum. The other effects seem to be alright. The only way I can get rid of the hum is to turn down the Sansamps treble knob practically to zero or turn it off entirely. I also use the 9-spot pedal connector if that helps at all.

Bass --> Boss Tuner --> Crybaby Wah --> Sansamp Programmable Bass Driver DI --> Big Muff Pi Distortion --> Bass Ballz --> Amp

Is it something in my chain that's causing this, or it's order? I was thinking of getting the Boss NS-2 but do I really need it in this situation?

[bassbrad]

Originally Posted by Insomnia_Junkie

I have gone through the topic archives but haven't found anything to help me out. I cant quite seem to get the hum/feedback out of my effects chain. Whenever I activate my Sansamp Programmable Bass Driver DI I get a steady, loud hum. The other effects seem to be alright. The only way I can get rid of the hum is to turn down the Sansamps treble knob practically to zero or turn it off entirely. I also use the 9-spot pedal connector if that helps at all.

Bass --> Boss Tuner --> Crybaby Wah --> Sansamp Programmable Bass Driver DI --> Big Muff Pi Distortion --> Bass Ballz --> Amp

Is it something in my chain that's causing this, or it's order? I was thinking of getting the Boss NS-2 but do I really need it in this situation?

I'd suggest movin the SAPBDI to the end of your chain, it may be overloading the lower impedence EHX effects causing that horrible hum ot it may also be a phasing issue that also might be corrected by the move.

[Insomnia_Junkie]

Originally Posted by bassbrad

I'd suggest movin the SAPBDI to the end of your chain, it may be overloading the lower impedence EHX effects causing that horrible hum ot it may also be a phasing issue that also might be corrected by the move.

Unfortunately it does the same, I tried dialing my tones on the sansamp differently to limit the hum (which it did) while still keeping the same tone but I don't wanna even use it if it hums as much as it does on a completely different tone I don't like. Unless everyone who uses F/X get hums and just drowns it out while playing? I'm still looking at the Boss Noise Reducer but I don't want to get it if there is some way around this, you know what I'm saying?

[niftydog]

Treble knob? For hum? Can you try to expand on the description of the sound a bit?

First thing I'd recommend is an isolated power supply like the Voodoo Labs PPII.

But, before you do that, consider taking some time to make sure you're not overloading your power supply.

...but before you do that, make sure all your pedals work properly individually. Test each pedal by itself one at a time, then add two together, test, add a third, test etc etc.

[Insomnia_Junkie]

Originally Posted by niftydog

Treble knob? For hum? Can you try to expand on the description of the sound a bit?

First thing I'd recommend is an isolated power supply like the Voodoo Labs PPII.

But, before you do that, consider taking some time to make sure you're not overloading your power supply.

...but before you do that, make sure all your pedals work properly individually. Test each pedal by itself one at a time, then add two together, test, add a third, test etc etc.

I've already tested all my pedals and its just the Sansamp. How would it be overloading the power supply if its just one pedal that does it? The hum goes away when I drop the treble down the just about 0 but I have no hihg end.

[niftydog]

Well, that wasn't clear from your posts - hence why I suggested you strip down your rig to one pedal! So, just the sansamp by itself does it. Well, it can only be two things.

• The power supply and the sansamp have an undesireable interaction - this doesn't necessarily mean either are faulty, but they might be incompatible.
• The sansamp is faulty.

Tried it with batteries?

Again, the word "hum" implies a very low frequency noise - like 50-120hz. Is that what you're hearing? And it goes away when you turn the treble knob? That is rather unusual!

[Insomnia_Junkie]

Originally Posted by niftydog

Well, that wasn't clear from your posts - hence why I suggested you strip down your rig to one pedal! So, just the sansamp by itself does it. Well, it can only be two things.

• The power supply and the sansamp have an undesireable interaction - this doesn't necessarily mean either are faulty, but they might be incompatible.
• The sansamp is faulty.

Tried it with batteries?

Again, the word "hum" implies a very low frequency noise - like 50-120hz. Is that what you're hearing? And it goes away when you turn the treble knob? That is rather unusual!

hmm I dunno, I should probably clarify I don't think it's much of a hum as it is a constant hiss, like when you jack your volume up all the way. I figured it was that at first and adjusted all my volume knobs accordingly, problem was that when I would use the pedal or just the dry amp one would be really low or the other really high. I even played with the treble and got varying, disappointing results. So is this more of a problem with my EQ, do I just need to spend forever trying to get everything perfectly balanced the way I like the tone, treble, etc... hiss free or does this happen with other pedal users?

[niftydog]

Hiss is often an indicator of a bad gain structure - usually too much gain has been applied at one stage and is being compensated for by the following stages actually attenuating the signal back down to where it should be.

You should be aiming for unity gain (input volume = output volume) from everything in the signal path (except for boosters, of course.) All the gain for amplification purposes should, IMO, come from the preamp and power amp.

BTW, I'm talking gain in the engineering sense, not in terms of distortion "gain".

Bear in mind that EQ controls are gain controls, just with a limited bandwidth. So don't boost EQ excessively at any point, but in particular try to avoid boosting it early in the signal path.

Proper gain structuring is hard to describe, but essentially you want to start with the strongest signal you can muster without overloading the first signal processing stage. Now, that doesn't mean you should dime every knob on your active bass!

From then on you want each input stage to operate at it's optimal point, which is usually roughly around 85% of the way to the point where clipping starts. Then, adjust the output volume control so that it gives the same volume as when the device is bypassed. Repeat throughout - compensating for EQ adjustments when you make them.