Brown note popping sound when switching from overdrive to clean

[samtech60]

I get an occasional pop when engaging and disengaged overdrive from clean to dirty not all the time ? Seems like some kind of voltage inrush issue with relays? Checked all grounds and all tests fine?

Also debugging presence non functioning issue? This is the old layout from the version I built any suggestions ?1 I tested and checked every connection I checked NFB loop all the way through also ?

These were a few small problems I wanted to finish up the amp sounds good also I feel it's a bit bright ? Any recommendations to darken up abit? Want abit more mids and lows ?

[Stevem]

I would suggest that you post a schematic or at least some good photos if you want folks to take the time to help ya out.

[samtech60]

This exact layout

[samtech60]

Thanks for any input I thought I might try and add some .01 ceramic caps across the relay diodes? I also can't get any presence out of this either checked the NFB and all components ? Potentiometer , 1mf cap and all wiring? Other than that it sounds great! I used a Hot rod deluxe output transformer and older heavy duty power supply .

[R.G.]

(1) Can you post a schematic, not just a wiring diagram? It enable us to do much more to help you.
(2) A pop in an audio circuit is always (except when it's actually part of the signal itself!) a sudden change in DC level.
... If it happens when you're switching something, you're switching between two different DC levels.
... If it only happens sometimes, then sometimes the two levels are not far enough apart to cause an audible pop.
... If the pop is worse the longer you wait between the switching incidences, it's probably a leaky capacitor or wandering bias point.
(3) relays can couple pops into the signal itself by
... the sudden change in voltage across the coil gets coupled through capacitance to the signal contacts; this is "the pop is in the signal itself" case then.
... the coil voltage change get coupled to a nearby grid wire; this is then "the pop is in the signal itself".
These will happen every time or every other time the relay is activated or deactivated, not being only sometimes.
(4) So - when, and what else is happening when the pops do occur? Always at relay activation, but only sometimes?
(5) It's not likely to be a voltage inrush on the relay itself, unless it's capacitive coupling, per (2)

[samtech60]

It only pops sometimes when switching between normal and overdrive ? Its definitely only when switching and not all the time .. Bias is at 34ma I'm running 6L6s ? It's an interesting problem I appreciate your time thanks

[samtech60]

I will check every capacitor

[samtech60]

As far as I recall, Brown Note never provided schematics - only layouts

[FUCHSAUDIO]

I would add a 1-M cap to the output of the V1b coupling cap to ground.
I would put 10-Meg resistors from the swinger to the nc and no contacts on the relay(s).
I would add a 1uf electrolytic to the relay diode.

that should clean things up...imho of-course.

[R.G.]

Not bad advice at all. Anywhere there's a coupling capacitor switched to "open", it has the potential (!) to cause pops when it's reconnected.

I spent a couple of hours trying to draw out a schematic from the wiring diagram. It's not done yet, but when I get to connecting up stages through the relays that ought to give a better view of what is and isn't a likely source of popping. I have some gripes with the wiring diagram (of course... ). The grounding scheme is one of those that was presumably tinkered into quietness and uses the chassis as all of signal ground, shield ground, safety ground, rectifier return, and sewer ground. This can be made to work, of course, but is hard to tell from a layout. Some of the component connections are incomplete, but there are reasonable guesses that can be made, some component values are unreadable (to me at least) but that won't account for popping issues.

I'll get some more done later.

[samtech60]

Thanks RG and Andy ! Andy sounds like some excellent suppression techniques will do! RG are you the guy that has the diy effects geofex pedals page? I was on your site alot 20 plus years ago? You have some fun circuits and thanks for your time

[R.G.]

samtech, can you look over the layout versus how you actually have the amp wired? The wiring to the relays doesn't seem to allow the signal flows that have to happen so the amp will work. Especially the relay closest to the input jack, but could you check them both?

Edit: forgot - yeah, I'm that R.G. Glad it was some help to you!

[samtech60]

I can tell you my overdrive enable and clean , and boost which just pulls tonestack out are working and my tonestack is also working. I just get these pops when switching from clean to overdrive. Thanks RG and appreciate your help

[R.G.]

Glad I could help.

The schematic is largely complete according to the layout. However, if the amp is really wired that way, I don't think it would be working as expected. It is always possible that I do not understand the way it works, or that I am misreading the layout, of course. I hate to think I just don't understand it, because then I will have to go go learn some more, and that always hurts.

So I wondered if perhaps I'm not reading the wire layout correctly. There are a couple of places where the wire lines are a little hard to read and I had to guess about where the connections are. These are mostly in the topmost relay area.
Specifically, referring to the magnified view:
The upper right turret carries signal from the second triode stage plate to the relay for switching between clean and overdrive. There is a fuzzy black line on the layout that goes from the turret at upper right (where the orange wire comes in) across the upper right pin of the relay to the second pin down on the left side of the relay.
> does the wire from the most upper-right turret, where the orange wire comes in, connect to the upper right pin of the relay, as shown by the green line I put in?
> does the wire from the turret with the orange wire coming in connect to the second pin down on the left side of the relay as shown by the added black line I put in?
To my failing eyes (and blowing the picture up by software...) I can't tell if it connects to one of these relay pins or both of them. I also can't tell if there is any connection to the upper-right relay pin at all, only a fuzzy black line going over it to the left row of pins on the relay.
I was hoping you could tell me how you actually connected the wires.

[samtech60]

Well, RG we have definitely confirmed that the Amp Garage has a different layout than mine original. They must of had some debugging revisions along the way think
I downloaded directly from Brown Note site in 2006 this one of mine has a few errors bass pot red wire from wiper pot to outer leg but, it's definitely operable.

I never bothered looking too much at the relay circuit on the one from Amp Garage because mine was already built and because I had my own layout? Here is your exact analysis which caught error brilliant RG ☺