popping noise on OD switch

[dude]

I know this has been answered before, I searched but couldn't a related tread.

first stage cathode is on a switch on the amp, when the overdrive is switched, a pop same when turned off.
I believe I once solve this in another amp with a small cap but totally forgot what value and where.

al

[VMS]

Are you switching the cathode capacitor or the cathode resistor?

If capacitor, then put 100k resistor across the switch.

[dude]

Are you switching the cathode capacitor or the cathode resistor?

If capacitor, then put 100k resistor across the switch.

Both, from a 2.2k alone to a 1k with a 22uf/25v cap in parallel. On/off single pole switch mounted to amp chassis has three lugs, ctr to tube cathode.

Thanks in advance,

al

[VMS]

I think there is always a slight pop when you change the bias of the tube.

I would use the switch (with the 100k resistor) to cut the ground connection of the 1k resistor and the 22uF cap.

[dude]

I would use the switch (with the 100k resistor) to cut the ground connection of the 1k resistor and the 22uF cap.

Switched the ground on the cathodes with 100K across the 1K/22ufcap to ground ,still pops rather loud?

[VMS]

I still think it pops because the bias of the tube changes, but the pop is a good way to inform the audience that they are about to experience an epic guitar solo. 


Is this your setup right now?

Does it pop if you remove the 1k resistor?

[dude]

Yes exactly and the same values, pops loudly.

I remember I had a popping on the standby switch of a reissue  Ampeg amp once and solve it by using a filter off the standy bot the voltage was the B+.

Any way a small filter somewhere in that circuit would help?

I see other schematics from Trinity Amps wired as your schematic with no 100K or any filter cap to ground off the second stage of the cathode??? But mind pops loudly according to volume setting.

Mine is on the first stage cathode of the pre-amp and I'm using a 6eu7 same gain as an 12ax7 just different pin out.

Here's the schematic that I'm dealing with, I had another thread going on some problems with this amp. Converted to 6L6's and it sounds great, very clean but with the setup as your diagram that extra OD is perfect.

I took the 2 input out, just cut the 100K input grid and put the switch there.

Sure would like to get that loud pop out. A lot of the resistors are CC's that wouldn't cause the loud popping?

Thanks in advance, I appreciate all the advice, I've learned a lot the pass 6 months on this forum. I'm actually startling to understand what I'm doing, ha. Great forum.

al

 

[dude]

If I cut out the 1K only pops the first time then no pop.

But the distortion is not as good as with the 1K in series with the 2.2k.

I've seen other boosts set ups wired the same with two 2.2K and the cap like your schematic so I guess you get about 1K when on in parallel.

Still changes the bias, the cap alone doesn't.

Something there's no fix for?

I'll just take the r out and just switch the cap maybe lower the cathode r to 1K5.

al  

[jjasilli]

Would it help to put a 1M resistor across the SW?

[dude]

Yeah, I did that with the resistor it still pops.

Just the cap and a 100K good to go without the 100K it only pops on the first time. I guess once the voltage goes across that cap the 100K does it's job. The 1 meg, probably is even better.

The cap doesn't change the tubes bias, the resistor does. I think it will always pop.

Maybe a small cap from the switch to ground? But with a 1K5 and the cap switched it's a pretty good difference.

Thanks, for all you're advice.

al 

[PRR]

> the distortion is not as good as with the 1K

Then it is gonna pop.

Put a volt-meter on that tube's plate. Watch what happens as you flip the switch. I dunno your circuit, but I'll guess 200V switch open and 150V switch closed. You are changing the tube's bias. That's probably the different distortion flavor you favor. But you can't switch a (SE) tube's bias without a pop, not without some much more complicated trickery.

[Shrapnel]

The other thread about MOSFETs and MOSFET Follies suggested looking up MOSFET Follies on Google for more uses.

There's one that uses a MOSFET as the actual switch on the cathode of the output tubes.

SOURCE: http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm  Gonna need to scroll down to it, about most of the way down.

I'd Consider attaching the image itself here, but with words like "No permission for serving from web sites other than http://www.geofex.com." attached, I don't want to get anyone in trouble.