Maestro S+H ticking in bypass

[AlexK]

I finally got my S+H filter working and it sounds great.  I used the GGG layout and added the Tonda mods.  One problem I'm still having though is a ticking sound only in the bypass mode.  I'm true bypassing it w/ a 3PDT (LED also) and the clicking is pretty loud. I'm not using a 1044 or anything like that, I just have 2 9VDC jacks and I'm powering it with a Voodoo Labs Pedal Power 2.

I saw a couple suggestions in the archives about beefing up the ground connection directly between the input and output and also adding shielding on the input and output.  I did both and I still have the problem.

Are there any other ideas about how I could stop this ticking.  I think as-is it's unusable for gigs.  Maybe I could make a seperate true-bypass box?  Would that even help?  I've also considered shorting the input to IC5 (the LFO opamp, I think) to ground when it's off to actually disable the LFO.  Does this sound like a good idea?  I'm hesitant to use this b/c I'd need to use the pole that's switching the LED on for this, doing away with the LED.

Thanks for any suggestions,
Alex

[soggybag]

I wonder if you could run the LFO through the by pass LED? If you were using a 3 pole switch it could disconnect the LFO signal when the effect was bypassed and you could tell the speed by looking at the light when it was on.

Of course I have no electronic ability. I went ot art school. I can only make things that look like the picture.

Congrats on getting your working. I'm still working on mine.

[ExpAnonColin]

You could try using a grounded input bypass scheme.

http://www.banzaieffects.com/products/bigpict/switch.gif

The lower one.

Sometimes that helps, although in more cases it helps to stop oscillation.

If the ticking is extremely loud, it's probably nota shielding problem, but rather a problem with the circuit itself...

-Colin

[Dan N]

I wonder what would happen if you isolated the power supply to the lfo chip. On the schematic I am looking at it is IC5. Run the power through a 100ohm resistor then a biggish cap to ground (47 to 100uf) for both the + and - rails.

I once thought I would be brilliant and make a Gristlizer with just a quad and single op amp. You want ticking? Put an lfo in the same chip with the audio signal. And no way to fix it.

Good luck!

[AlexK]

Guys,

Thanks a lot for the good suggestions.

Colin - this was actually the first thing I thought of.  I tried grounding both the effect input and output while in bypass mode and it didn't get rid of the ticking.  Thanks though.

Soggy - great idea!  I'll have to think more about how I'll do this though.  I hadn't even considered it.  There's actually a diode in the negative feedback of the LFO, so maybe I could just replace that diode w/ an LED.

Dan - thanks a lot for the idea.  This might not be too hard to test out...I could just bend the leads of the IC from the socket and put a decoupling network right into the sockets.

I'll report back if anything works  

Thanks again,
Alex

[Paul Perry (Frostwave)]

I once thought I would be brilliant and make a Gristlizer with just a quad and single op amp. You want ticking? Put an lfo in the same chip with the audio signal. And no way to fix it.

Well for a Gristlizer, that would possibly be a 'feature' :wink:

[AlexK]

Well, I tried the supply decoupling for the LFO opamp and it didn't help.  Damn, I was really optimistic about that one too.

Now I have to figure out how I'm going to do the LED thing.

-Alex

[AlexK]

I have an update on my Maestro S+H ticking problems.  I tried disconnecting the output of the LFO opamp from the circuit when in bypass mode and also driving an LED off of this node w/ an opamp buffer driving it (to isolate it from the LFO).  This worked really well in bypass mode, but I then had ticking in the "on" modes.  In both the filter mode and sample and hold mode there was the loud ticking.  So I just traded one problem for another.

I think the problem was that I was sending the LFO signal into the bypass switch and it was coupling through inside the switch.  If I do the same thing, but just hand connect them without going into the switch, everything works fine.  One option I have is putting in a SPDT switch really close to the on/off switch and using that to turn off the LFO.  When I turn it on and off I'll just stomp on both.  This is really the LAST thing I want to do though.

So I'm back at square one.  I'm going back to the beginning and trying to get the tick out of the bypass mode without switching the LFO off.  Is there anything I haven't thought of?

Thanks a lot,
Alex