strange MASTER VOLUME noise (FIXED)

[talbany]

1W resistor is better than 1/2W of same value to decrease noise into grid

It's called shot noise
T

[Structo]

Tony, not to argue but I always thought shot noise was from current in semi-conductors?

As in Schottky noise.

[richon]

On the grid is no current (or súper little) so I still Believe is a was resistor

4 of the same Batch I tried were super noisy , like antennas

[Structo]

I use 1 watt resistors pretty much all through my amps.

Less noise and physically bigger = easier to work with.

Are you using metal film, carbon film resistors or carbon composition resistors?

[richon]

METAL OX 3W in the filters
Carbon Film 1W con plates
Carbon Film 1/2W everywhere else



I was thinking of going 1W for everything before my amp, but I had no patience and started with what I allready had at hand


Right now the amp is HAPPY and SILENT when not strumming on the guitar

F****** resistor

[Structo]

Yeah, sometimes you just gotta do with what you got.

BTW Dumble used Vishay/ Dale RND65 mil-spec metal film resistors on the plate loads for a period in the early to mid 1980's.
They are rated at .5 amps but since they are mil-spec they are more equivalent to 1 w resistors.

I like them too.

The rest in the preamp are carbon film in a lot of amps although you can find just about anything in some of them.

Some say he just used what was available to him.

I am not sure how available parts are for you.
Do you buy online or do you have a local electronics shop nearby?

Here are the Dale RN65D:

http://goo.gl/bN08h

Another thing is the plate voltages on the preamp.
It helps the tone to have it in the ranges listed below.

Shoot for ~190 on V1, ~200 on V2 and ~280-300 on V3 (phase inverter)

As for grid voltages, they aren't supposed to be very high.

I have 1.59vdc on V1 and 1.69vdc on V2.

Here is a semi recent voltage chart.

The B+ voltages may be different for since you probably didn't use the same power transformer as I did.

Also, do you have the FET preamp installed?
If not many recommend that you put a 150K 3w resistor at the end of your dropping string to ground to simulate the FET load.

Hope this helps you.

[richon]

191 on V1(a/b)
200 on V2a And 330 on v2b (cathode follower)
335 on PI
458 for B+ in the first filter

No FET And 150k installed

[Structo]

You are looking good but I think the PI is a bit high.

Personally I wouldn't go over 300v.

[richon]

Why?

I have 82k/100k instead of the 100k/trimer/110k

My resistor for high voltage are 2.2k,22k,2.2k

[Structo]

Well the reason I said that is due to what has been observed on real Dumble amps.

If you want that tone then you have to abide by the "rules".

But, if you want a higher gain amp then you can bend the rules.

Having the PI voltages higher will increase gain and take a bit away from the sweet tone.

By the way, is this a Overdrive Special clone?
If so what #?

What value resistor do you have on the input grid of V1?

[richon]

Its a blues master preamp, with a "RIPPER"ish Overdrive , with one tube reverb into a classic power stage with 6L6

[Structo]

Ah, so different values on the PI.

EL34?

[richon]

6L6