4 channel 50 Watt winter project. about 30% done.

[nandrewjackson]

https://drive.google.com/open?id=1HECvI2ZzaxjVsQHH5sZtkN2GSTMdG0EL
https://drive.google.com/open?id=1achKz5c3ICXfuWiR4q3KSQxAhiLVnBFm
https://drive.google.com/open?id=1HAjf5pPVO9OWGkqgkHfO3W1O4g1tqI0X
https://drive.google.com/open?id=1HP_CwREEX0JrFoTqXXdjV0p3KzG1uAwI
https://drive.google.com/open?id=1XzhznkpL7UMNdAvumxP71H8k-vxnZar8
https://drive.google.com/open?id=1FQ4Raw6WQMxQvB-MOdd9fLmr--VQ2CT1


 Preamp up until the FX loop send CF is all wired up.

 
Ch 1 I’m calling “vintage clean” it’s one triode then to the FX loop send.

 
Ch 2 I’m calling “modern Clean” it’s two triodes, then to the FX loop send.  Ch 2 started off as the Soldano SLO clean channel, then I toned it down with negative feedback on the 2^nd triode. Last year I built the Soldano SLO circuit, then started modding it. The SLO clean gain control had to be at 25% or lower to really be clean, above 25% it starts gritting up with overdrive, hence the negative feedback, now that gain control can go to 50% and higher without overdriving.

 
Ch 3 I’m calling “vintage distortion”, Its basically a JCM 800 2204 – style circuit.

 
Ch 4 I’m calling “modern distortion”, It started off as the Soldano SLO / Mesa rectifier / style preamp, but after several prior builds of the circuit, I’ve switched to much smaller value coupling caps in the first few stages.  From the stock 0.02uF, down to 0.0068uF coupling caps.  I’ve seen Bogner high gain circuits that use these, and the Carvin Legacy also uses much smaller coupling caps in the preamp stages.  I think it’s a really neat circuit.  It gets rid of the floppy, muddy, bouncy, however you’d like to describe, Low end.

 
Last year, I built a 2 channel amp, with the “modern clean” and “modern distortion” channels that are going into this one.  I like the sound of both channels, but the smaller coupling caps simply don’t allow some sounds to come out of the amplifier.

 
The switching is a circuit using three integrated circuits to control the on/off states of “vactrols”.  I found some good light dependent resistors, they go from about 50K to 5M.  I rolled my own with LED’s.

 
The channels can be switched on the front panel with small momentary pushbuttons, and also by footswitch with momentary footswitch buttons.  I’ll be using a DIN 8 pin cable to run the footswitch. The front panel will have LED indicators for each channel, as will the footswitch.  I’m having to use all white LED’s with different colored lens mounting clips.  On last year’s build, I used different colored LED’s and found out the hard way about different LED voltage drop / current draw.  Since the LED’s for illumination and LED’s in the “Vactrols” are all in parallel, some will be brighter than others if they aren’t matched by their voltage drop / current draw specs.

 
I’m using a set of Classic Tone Transformers, 18105 Output transformer (40-50 watt) for 2 6L6/EL34 output.  18107 Power transformer.  It has taps for all kinds of input voltage, negative bias tap, and taps for tube rectifier, but I’m gonna simply use diode rectification. It’ll have negative bias voltage, and of course, 1 Ohm resistors on the output tube cathodes for easy biasing.

 

 
AND THE ELEPHANT IN THE ROOM

 
turret strip + point to point construction !!!!!!!!!!!!

 
yes, it’s a mess, but this is my preferred build method, other than a PCB, It’s the only way to get this much circuit into this style chassis. 

 
I suppose I could learn some computer program for PCB layout, but I’m not going to unless I find the motivation to do so, which I don’t see happening any time soon.