Ground question

[Joe6v6]

I am building a Deluxe Lite From Sluckeys Layout & schematic. I have been using the same ground scheme for some time now and it has been a long while since I have had any issues with ground induced humm. I always ground the filter caps for the power section together on the power end of the amp & any caps that supply the preamp are grounded near the input jack along with the preamp cathodes & any grounds coming from the controls. I have a 40-20-20-20 cap can that would work very nice in this amp but it would only have one ground, so are there any opinions as to weather this may be an issue in this particular amp. If so I will use separate caps as usual.  .  .   Joe 

[st]

All your favourite Fender amps have the can cap, and it worked fine for them. Internet wisdom, on the other hand, has it that it's not a good idea... To a certain extent, it's a question of belief...

In my experience, an amp with a can cap, good layout (!) and decent wire dress (!) can be as quiet as any...

[punkykatt]

I have built at least a half dozen of so Fender style amps with the cap can you describe and never had an issue with hum.

[Joe6v6]

In my experience, an amp with a can cap, good layout (!) and decent wire dress (!) can be as quiet as any...

I have built at least a half dozen of so Fender style amps with the cap can you describe and never had an issue with hum.

Sounds good to me, Im sure there are plenty of others who agree also, so I will be moving forward with the can - -   -    Thanks : Joe

[sluckey]

I think that JJ can is perfect for this little amp, especially if building with a small chassis.

[Papa Jim]

I've started building that same amp and plan on using a JJ can cap. I've used twice before with great low noise and hum results.

[sluckey]

All your favourite Fender amps have the can cap, and it worked fine for them.

I've only seen cap cans in the Champ series and Princeton series amps. All of my favorite Fender amps use axial caps. Sure, the caps are located together and covered with a "dog house" which I suppose you could call a can but it's not the same and you know that ain't what Joe is talking about.

[tubeswell]

Cap cans are less of an issue in uncomplicated circuits. But if in doubt, use a separate cap for the pre-amp - its only a couple of bucks

[st]

All your favourite Fender amps have the can cap, and it worked fine for them.

I've only seen cap cans in the Champ series and Princeton series amps. All of my favorite Fender amps use axial caps. Sure, the caps are located together and covered with a "dog house" which I suppose you could call a can but it's not the same and you know that ain't what Joe is talking about.

True. I typed quicker than I could think. Guess I should have said "my favourite Fender amps". Even so, whether in the dog house or on the board, as in the tweed amps, all Fenders have poor power cap grounding schemes that are very similar (yet not the same) to the grounding scheme that a can cap necessarily has. None of them has the star/multiple star ground that the Internet tells builders to use.

[sluckey]

all Fenders have poor power cap grounding schemes that are very similar (yet not the same) to the grounding scheme that a can cap necessarily has. None of them has the star/multiple star ground that the Internet tells builders to use.

So what? More than one way to skin a cat. If you look at a Fender layout with a dog house you'll see two grounds wires coming out. One is the power ground and heads toward the PT HT center tap chassis ground. The other is a preamp ground headed toward that brass plate behind the front panel. That's the basis for the grounding scheme that I and many others use. The difference is the brass plate. It's been replaced with a buss wire that connects to chassis near the input jacks. The key is keeping the poorly filtered, nasty power amp currents close to the PT and far away from the preamp grounds. Doing that is much more important than how you do it or what inet name you want to call it.

Fender did alright. Lot better than most. Even that brass plate served well for 30 years but became a bit of a curse in later life. There are still a lot of old Fenders kicking around. I expect to see them still ticking and being cloned even after I'm gone.

[Joe6v6]

Grounding, even thought it seems simple, can be confusing & frustrating to those who are new to building amps. I still remember the uncertainty when I first started just because there were so many answers to the same question, very confusing. ive seen pictures of someone running a separate wire for every grounded component in an amp to a single point. Everyone has their own way & when you have to deviate from that its cause for concern. I know in the past ive built amps that had the power caps & preamp caps grounded together that turned out fine, but like I said its been a long time since ive done it that way and I know from experience that some amps will tolerate it just fine & others will not.   .   .     Joe   

[st]

Fender did alright. Lot better than most.

I agree. We agree. I was just emphasizing the fact that Fenders are okay despite not complying to generally-approved grounding schemes. Merlin Blencowe writes "The only 'proper' way to ground an audio amplifier is by the multi-star ground scheme", a statement that is probably right in theory. Others advocate single-star or bus grounding schemes. Not a single Fender that I know of complies with any of these schemes, and still they are excellent amps.

Grounding, even thought it seems simple, can be confusing & frustrating to those who are new to building amps.

Thus, my point was that grounding should not be your primary concern. Bad board design/components layout and poor wire dress are also (as?) bad for noise and in my experience almost always harder to remediate than a ground loop or other ground related problem.

(I definitely wasn't talking about the Deluxe Lite layout, as haven't even studied it and have no reason to doubt it is good).