SKYLINER build - inspired by ODS #124 and #060

[Stephen1966]

Hummed and ahed about the footpedal - was thinking I would make an intricate design in mahogany, then thought stuff it! There has to be a nice enclosure...!

There is; the Hammond 1455L2202BK. Wide enough (220mm), not too deep and just tall enough to fit the Alpha switches.

First off, the amp isn't finished yet, I have a lot of work and little time, but it's getting there. I'm working on a revised schematic and included in there is the updated schematic of the footpedal. After trying it out I've decided to go with the simpler version of the pedal, i.e. without the switch to cut the FET in OD. I figure, I just won't need it. It simplified the design and after testing, it all worked as planned.

Here's the enclosure detail:

Footswitch version 2.pdf

And a couple of pictures to give you an idea:

IMG_20220402_183916.jpg

IMG_20220402_183927.jpg

IMG_20220402_183325.jpg

[Stephen1966]

More fun and games over here

I was curious to see what my pickups were putting out voltage wise. It occurred to me that if I could establish a baseline voltage for the audio generator I could use this for testing the signal and PI trimming in the amp. I don't know if it makes an enormous difference to the voicing of the amp, I've still to try it out. What I have so far, is sounding very good as it is and I don't see myself making any real significant changes to the set up but this could be really useful. Not just for setting up the amp and voicing it generically, but for setting it up for the intended guitar. I guess if you have a collection of gtrs with vastly different pickups you would go for some kind of middle ground, representing the cross section of the collection.

I'm using a pair of SD Hot Rails in mine and the bridge pickup is the hot version. For this test, I engaged both and used the scope to measure the Vpp and Vrms with the coils in Series and Parallel; each pickup is individually switchable between series and parallel. I was interested in seeing the maximum output so all controls were set to max and I used a fairly aggressive strum across open strings. For a more finely tuned approach we might try playing a few standards (whatever you are into) and looking for the baseline in those. It was the Vrms I was interested in, because this is the level I will be using to calibrate the signal generator.

As you can see from the pics below, the output of the pickups in series is much hotter.

SDS00031.jpg

SDS00035.jpg

The average max Vrms of the Parallel pickups was just over 330mV (rms), the Series pickups gave out an average 807mV (rms) which seems close to the recommended 1V I've seen elsewhere.

Maybe it's not worth reading too much into these figures, 1Vrms for the signal generator works fine, but I have some more testing to do now and I will try dialing it back to 800mVrms to see how that figures. We don't need a scope to find the output of the pickups either, it's just that when I connected up both the DMM and the scope probe together, my voltage readings on the DMM were about 60% of what the scope was picking up. A voltage divider effect possibly. Anyway, the two traces above were taken with only the scope hooked up.

Stephen