Still getting buzz with D'Lite build on OD setting. Ideas?

[markmalin]

... all that said, back in the day when I'd play through a 50w Marshall half stack up so loud that I had to learn to art of turning my guitar to keep it from squeeling, I should be able to deal with a little hum.

I guess the bottom line is, I've never built one of these designs before, and have never even played through one before. I have no basis of comparison other than Fender styles that I've either built or have repaired. If it's the "nature of the beast", fine, but if it's something I can change w/in the amp, I'd like to try.

Thanks for the input, guys. Much appreciated. As always, I'm learning a lot.

Mark.

[greiswig]

4.) If I touch either the bright cap or the 500 pf cap on V1, it gets REALLY loud (presumably because I become the antenna).

Why do you think this represents any kind of problem in the amp?

I guess the fact that if I touch either cap the thing buzzes. Yah, it sure points to the Strat. I'm just having a hard time reconciling having to deal with so much noise. I thought if there was some way I could shield things better I could keep the single coils from buzzing so much, but you're right... it points to the guitar / high gain amp combination.

But why doesn't my 5E3 with an overdrive pedal do this? Is that because it's high gain input, rather than high gain w/in the amp? Isn't both scenarios amplifying a 60hz hum?

Mark

Are you comparing apples to apples? When you're testing this on your 5E3, do you have the chassis open? Are you standing right next to it like you might be on your D'Lite when you're tweaking?

There are ways to reduce hum from a SC guitar: I have a Tele with Bill Lawrence pickups in it that I like very much, and they are low noise. Purists will scoff at me, but I think they are a remarkable PU for the money. (PS - I have a set of Lindy Fralin's from that guitar FS...make an offer!)

[greiswig]

well mine does`t go away with humbuckers:-)
I guess i have to follow up Dobbhill`s advice.
I tried everything else i could think of.
Pity because i have to completely dismantle the entire relay section.
My chassis is a bit smaller;i even had to saw off most of the sides from the relayboard to make it fit between the turretboard and the front switches.But if most of the hum goes away this way it will be worth it.

Ed...I'm curious: I get a 60Hz hum (actually sounds like it is an octave up from that, but I wouldn't swear to it) when I have nothing plugged in and the OD switch on. It is faint, and certainly not something that prohibits me from using the amp. But it goes away entirely when I engage the PAB switch. Does yours do the same?

[Ed de Jager]

No,actually i have the same untill i switch on the OD then i find the hum annoying.
Do you have the relays energized when PAB/OD on or in the clean mode.

[greiswig]

No,actually i have the same untill i switch on the OD then i find the hum annoying.
Do you have the relays energized when PAB/OD on or in the clean mode.

Relays in my unit are normally NOT energized...so theoretically if this is an issue I should be getting it with the PAB engaged, too, unless the leads are somehow reversed so that the hum is self-cancelling?

[Ed de Jager]

Mine are not too.
I am going to try and reverse the PAB tomorrow and see what will happen.
It must be in the relay section.
I was not sure but i listened to some tapes from before i put the relays in a few minutes ago and did not hear the hum in the OD mode.

[greiswig]

Mine are not too.
I am going to try and reverse the PAB tomorrow and see what will happen.
It must be in the relay section.
I was not sure but i listened to some tapes from before i put the relays in a few minutes ago and did not hear the hum in the OD mode.

Interesting...it is hard for me to tell. I just noticed the hum after some tweaks, but I can't rule out that it was there before. The relays were installed from the beginning. I tried putting a 1uF cap across the coil while it was humming, and it had no effect at all on the hum. If that were the problem area for me, I would have expected to hear some drop in hum as the ripple was filtered out. But maybe I need to try a larger cap.

Good luck, Ed!

[Ed de Jager]

Because i wasn`t that happy with the OD sound and to get the hum out i descited to start from scratch and take out all of the switching(both relays and front)and hardwire the amp in OD mode so i can fully concentrate on that.
There is very little noise now and i will try and get it as quiet as possible h changing the leaddress but the humm is gone.
After that i will put in some alligator clips on the turrets for the caps and put in trimmers for the resistors.
Should be fun.

Ed

[markmalin]

Because i wasn`t that happy with the OD sound and to get the hum out i descited to start from scratch and take out all of the switching(both relays and front)and hardwire the amp in OD mode so i can fully concentrate on that.
There is very little noise now and i will try and get it as quiet as possible h changing the leaddress but the humm is gone.
After that i will put in some alligator clips on the turrets for the caps and put in trimmers for the resistors.
Should be fun.

Ed

Ed, Please keep us posted on this. It's very interesting that all the hum is gone with the OD hard-wired. If it was an issue with relays, I wonder if you could try shielding the relay board (i.e. cover it with a metal shield, grounded to the chassis) to see if that helps?

Anyhow, let us know how this turns out.

Mark.

[Ed de Jager]

The hum is gone... at last.
I put the kathode grounds to the bolt next to the volume ala #124 and completely rewired the relays,paid close attention to lead dress.
Also i put the wires to the bass and treble pots above the post and to the middle pot below.And i changed the 500pF ceramic cap on V1-7 to a polyester one.
At bandpractice the amp was all open under a big fluorecent light and it was surprisingly quiet.
O.k.there was some noise with the volume full open but not annoying like it used to be.Sound was great but off course not perfect.
Glad i have a soldering iron:-)

Ed

[markmalin]

Ed. Great news! Can you post pictures of your lead dress and how you wired the relays?? I'm curious to see how you did it.

Thanks!
Mark.

[Ed de Jager]

Sorry i haven`t got a digital camera.
I"ll see if there is someone with a camphone.

Ed

[markmalin]

...snip...
Also i put the wires to the bass and treble pots above the post and to the middle pot below.And i changed the 500pF ceramic cap on V1-7 to a polyester one.
Ed

Ed, can you explain what you mean "wires ... above the post". Did you mean above the "pots"?

I usually route things like Fender did, where the tone stack wires to the pots are along the chassis, then split them off and run them up to the individual pots. What I'm wondering is, if you ran the bass and treble wires "above the pots", do you mean the whole length of the front of the chassis? What route do they take from where they exit the board?

Were you specifically trying to keep the treble and bass wires away from the mid. wires??

Thanks,
Mark.

[Ed de Jager]

Yes,sorry,above the pots.From the caps to the pots.
I don`t know if this helps but the amp is quiet.
I am thinking that the cathode grounds did the most,then the cleaner wiring to and from the relays and maybe the wires to the pots also helped.
Wish i had a camera but i don`t know if that would of any help as i used blue wire only throughout the amp.
Bought a 100 meter spool a while ago for 9 Euros.
I am building on a,what you can call,low budget.

Ed

[markmalin]

I am building on a,what you can call,low budget.

Ed

Anch'io! Me, too. Thanks for the information -- I think I may try moving the cathode grounds as you did. I had been thinking that the fact that these are grounded to the buss wire, which is grounded through the input jack (as it connects to the aluminum chassis) and also grounded through where the buss wire connects to that ground lug makes for multiple paths to ground, and possibly a ground loop.

Anyhow, thanks for the information!
Mark.