Construction technique questions - snubber caps, etc.

[mlp-mx6]

I've asked this of a couple people before, but thought I would open up the topic to the forum - both for the exchange of ideas, and the mutual education that results.

Does it matter if the OD "snubber" caps are on the board, or MUST they be on the socket to achieve the desired result?

I had heard that grid-stopper resistors MUST be mounted on the tube pin to be effective. True? (seems to be, based on HAD's construction techniques)

What constitutes "good" lead dress? "Bad" lead dress?

Any other questions?

[Normster]

I've mounted the snubbers on the board and on the tube socket and really can't hear any difference.

As for grid stoppers, I mount them Dumble style 'cuz it looks cool, but Marshall mounts them on the board. I guess you could mount it on the board and move it to the tube if you pick up too much interference.

I know very little about lead dress, but I never have any problems with hum. I keep wires close to the chassis, twist damn near everything, and minimize parallel runs. When in doubt, I stare at Dumble chassis pics until it makes sense. I think the Trainwreck guys are the real lead dress experts. As I recall, they actually induce a certain amount of oscillation and feedback into the circuit by carefully positioning parallel runs.

My question...Just what are those critical lengths of wire that Dumble uses to tune his amps? Is he adjusting circuit capacitance using shielded cable?

[Bob-I]

I've asked this of a couple people before, but thought I would open up the topic to the forum - both for the exchange of ideas, and the mutual education that results.

Does it matter if the OD "snubber" caps are on the board, or MUST they be on the socket to achieve the desired result?

I'm with Norm on this one. I've done it both ways and can't hear the difference.

I had heard that grid-stopper resistors MUST be mounted on the tube pin to be effective. True? (seems to be, based on HAD's construction techniques)

Not exactly. The issue is that lead dress plays less of a part if the conponent is right at it's termination. If you mount the grid stopper 3" from the socket, that's 3" more that allows the wire to be an antenna and therefore lead dress becomes more critical. I've done it 3 ways, on the input jack, on the board and on the tube socket. All work, the tube socket is the easiest.

What constitutes "good" lead dress? "Bad" lead dress?

Any other questions?

That's a big topic and for another time.

[llemtt]

...
My question...Just what are those critical lengths of wire that Dumble uses to tune his amps? Is he adjusting circuit capacitance using shielded cable?

A better question... what kind of cable did he use?

A shielded cable is also a cap but with very unconventional dielectric material (pvc, teflon,...), who knows how this will perform?

Consider this: what happens if one foot of cable has 50pF capacitance at 1MHz and maybe 300pF at 20kHz?

Capacitance is everything but fixed in a cap it depends at least on:

Temperature
Frequency
Bias (DC) voltage
AC voltage
Pressure

Teo