1986 sounds wonderful, but many problems

[whitewave]

Hi,

in the last weeks I had many problems with this build, and finally I solved them using a double pole power switch, to switch both cables from main.
I had the chance to play it just at medium/low volumes, and it's very clean and organic, almost no crunch at all. I love how it sounds on ch 2, both with strat and Les Paul. It's too woofy on ch 1, but I knew that.

Anyway, I have some problems to solve.

1. If I'm playing and switch off the standby switch, the sound becomes lo-fi and scratchy, as it should. The problem is that it lasts forever, the volume doesn't die as it is supposed to do. Even if I turn volume to zero, something it's still audible.
If I switch power switch to off position, the sound come back at full volume for something like 5 seconds, then it dies suddenly with a pop noise.

2. If I turn the three tone pots and presence to 0 it loses much volume. This is normal?

3. Presence pot is only one being a little bit scratchy.

4. if I'm playing on ch 2 and turn volume on ch 1, where nothing is plugged into, I get a very muffled sound. Is it normal that ch1 volume interacts with ch1?
4.b the same happens if I'm plugged into ch2 and turn ch1 volume.

Amps is basically stock. It has a couple of F+T 50+50 filter caps, 33+33 on board. 150uF on first cathode. A split/shared cathode switch (the loud pop if I change it is normal?).

Thanks.

[neikeel]

Funny things you have been doing to create these noises

May I suggest you post some clear high res pics. Odd that it sounds 'woofy' on channel 1 that should be the brightest and sharpest of the two channels, oh and try a 10uF or max 25uF cap on V1.

Wonder if you have mixed channels with your shared/split cathode switch (you do not say what your other cathode values are?). Yes a pop is quite normal. You can put a 1meg R to ground, that might help. But usually avoid switching when you are playing.

Will wait for pics

[Reeltarded]

1. As it should, except for the residual forever scratch in stby, and the pop at the end of the volume ramp when turning off.

Hmm.. You have something going on in the area of the treble cap/slope area... You built a Fender!

Heh

[whitewave]

sorry for delay, some photos of internal wiring.
I followed Ceriatone's layout.

photo 1

photo 2

photo 3

photo 4

photo 5

[Reeltarded]

OMG you used purple bus wire!

I see the problem. Your PPIMV is not hooked up.

Just kidding. I go look now.

[Reeltarded]

Good news. It all works as it should.

Bad practice all around the dress from the .. from everything. You need to get your input wires down to the deck instead of that stylish waving thing that is half a loop around and over. Look at one of George's amps (or Neil's) for perfection in dress.

All the lead from the pots should dive straight to the deck, route to where they go, then straight up to the junction. Anywhere you have a loop in a power creates a transmitter, any loops in signal are antennas.

The channels do affect each other. Your's will crosstalk more because of lead dress. With the tones at 0 you have around 12db average cut on signal, ballpark.

I'll give it another look when I get a few minutes here, but looks fair as I see it.

[whitewave]

You made me laugh with the stylish waving thing.

I've a folder in my computer with many guts shot of various plexi, mostly by "boutique" builders. Some are works of art, some don't look that good.
This is the third amp I build, the other two being a couple of SLO, where I had to pay attention to noise since they're high gain
I could do this plexi better than it is, with shorter and straighter leads, but I decided not to just after looking at all this gut shots.
Do you think I have to cut them shorter? The fact that I have no noise or hum isn't a sign that general wiring isn't bad at all?

What about the standby behaviour?

thanks a lot.

[Reeltarded]

No need to cut, for the most part just use a tool to push the wires to the chassis. Things like that input loopish thing are asking for a parasite. I think somewhere later in the circuit is where signal is jumping in standby and creating the "ecccchhhhh" when you bash on the guitar inmthat mode. Gotta be.

[toner]

1. If I'm playing and switch off the standby switch, the sound becomes lo-fi and scratchy, as it should. The problem is that it lasts forever, the volume doesn't die as it is supposed to do. Even if I turn volume to zero, something it's still audible.

This is caused by the resistor you added across the standby switch. Is that resistor 10k? Are you trying to simulate lower voltage for a "brown sound" there? (if so, that's not a good way to do it)

I'm not sure what you are attempting to do there but if you are trying to maintain some plate voltage to prevent "cathode poisoning" when in standby, you need a much larger resistor to reduce the delay in the "scratchy" sound and have no sound once the voltage drops (100k or higher, 2 Watts+).

If I switch power switch to off position, the sound come back at full volume for something like 5 seconds, then it dies suddenly with a pop noise.

Some volume rise and a pop noise is typical when switching power off while in play mode (not in standby).

2. If I turn the three tone pots and presence to 0 it loses much volume. This is normal?

Some volume loss is natural, especially with the treble pot, but if you lose all volume, something isn't wired correctly (for a Marshall).

3. Presence pot is only one being a little bit scratchy.

That's normal for the type of presence pot you have.

4. if I'm playing on ch 2 and turn volume on ch 1, where nothing is plugged into, I get a very muffled sound. Is it normal that ch1 volume interacts with ch1?
4.b the same happens if I'm plugged into ch2 and turn ch1 volume.

Not normal!!! The unused channel's volume pot will affect gain and frequency response a little but you shouldn't get a "muffled sound".

A split/shared cathode switch (the loud pop if I change it is normal?).

Loud pop noise is typical with that switch. (I'm not sure how to fix it but Neil's suggestion may work.) Turn the volumes down before switching.

Lift your preamp and PI grid wires (V1-V3, pins 2 and 7) up away from other wires, especially the heaters to reduce noise.

Last, but not least.... purple wire is known to cause serious problems... Good luck!

[Reeltarded]

LOL told ya!

I am thinking dress is more than one of he issues, one of those being the crosstalk, no toner? Jist imagining what is there.

[toner]

...I am thinking dress is more than one of he issues, one of those being the crosstalk, no toner? Jist imagining what is there.

The input jack wiring doesn't look that bad, but yeah, who knows what's going on under the board.

[whitewave]

nothing in particular under the board, the wire just come out of the board the way you see them