A Collection of #124 Information (Schematics, Layout, etc.)

[David Root]

I'm still trying to get this straight in my mind.

1) Ratio pot precedes Level pot, yes/no?

2) Ratio pot is 100K Lin, yes?

3) Level pot is 250 K Lin, yes? (Or audio taper if you prefer).

[David Root]

I'm still trying to get this straight in my mind.

1) Ratio pot precedes Level pot, yes/no?

2) Ratio pot is 100K Lin, yes?

3) Level pot is 250 K Lin, yes? (Or audio taper if you prefer).

[ChrisM]

The level pot goes after the ratio pot. The level governs the overall signal level.

Ya 100K linear for the ratio.

Level is 250K linear.

Imo both pots should be audio taper. I don't like the feel of the stock tapers in this circuit.


Just a side note when I was trying to understand 124...The PAB footswitch is not hooked up. Stock the footswitch will not switch the PAB on and off.

[David Root]

Thanx Chris. That's what I thought. As it happens I am also using audio taper on both pots., don't have any linear pots that big.

On the PAB, odourboy's schematic indicates that, but it's OK because I haven't tried to add that yet. I must say I like the idea having a frequency selective boost because if you just un-ground the whole tonestack it would mush up the ODS circuit I would think.

[ic-racer]

Hmmm... Agreed. Seems to me the labels on the 'Level' and 'Ratio' pots got switched. The FET board power is messed up also - swapping the cap+ and V1 plate wires with the V2 plate wire on the terminal strip lugs would straighten this out I think.

Good pickup. I don't have the original Layout file, otherwise, I'd change it.

Can the current one be edit, or does anyone else have the original?

talbany did the layout here: http://ampgarage.com/forum/viewtopic.php?t=6774

Realize the flow of information is as follows:

THE AMP ITSELF -> The Pictures -> The Schematic -> The Layout.

Realize 1) the amp was recapped after the pictures and 2) the layout was the last thing to be done, so it may still have an occult error or two.

[criszou]

can any one add line out?? so I can plug in directly to the sound card.

Thanks

[ic-racer]

The layout image on the first post has been updated to fix all known mistakes. Thanks to Talbany!

[Structo]

Thanks guys.

That has to be one of the best looking layouts I have ever seen and I refer to it often.

[martin manning]

The layout image on the first post has been updated to fix all known mistakes. Thanks to Talbany!

Yes, great and thanks again, Tony! =) But, there is still one error to correct- The last filter is wired incorrectly. =( Here's the correct layout from #124 photo.

MPM

[thorgir666]

Hi guys,

I was wondering if anyone did a bom for the latest #124 schematic/layout?
One that is correct? If not please do, as Im a lazy bastard:)

Best regards, Torgeir

[ChrisM]

Still don't think the OD pots are labelled correctly (value and name).

[Structo]

This is what the files show.

[Dino]

Hi dont know if you guys can help me but i have built a 1970's style Dumble and when i take it out of standby it makes weird squieling sound...
I've gone through the diagrams and the circuit but cant find any mistakes..;....;....

HELP

[selloutrr]

sounds like the output transformer wires connected to your power tubes are reversed. try switching them.

[Structo]

To test that, disconnect the wire to your presence pot.
If it stops squealing you know you have your OT secondary leads backwards.
If you cut the wires and now they are too short, you can swap the two wires coming from the phase inverter plates.