The three
pedals pictured above are an original 1970s MXR Distortion (Left), JN
Modified Distortion (Middle) and JN Vintage Distortion (Right).
These were
the first attempts to make effect pedals from scratch. The PCB was drawn
by hand with a Dalo etch resist pen then etched using Ferric Chloride.
All parts were bought from a local electronics retailer.
The 70s MXR
Distortion was bought 24 years ago (second hand) for £22, it has
survived countless gigs and practices. It produces a smooth warm distortion.
The track layout and components were the basis for the other two pedals.
I had a schematic
from the internet but the layout was different from the MXR, so I copied
the MXR tracks and matched the components to a list from the web.
Modified
Distortion
It has twice the amount of old style diodes in series, which produce more
cleaner increased output, but still give a mild, smooth overdrive, an
increased value output pot, a newer IC which gives a clearer signal with
less hiss and an increased input and an increased value Capacitor which
filters less bass frequency giving a fatter sound.
Overall the sound is very good it has more output, more sustain and better
clarity / response than the original MXR. This was constructed in a Die
Cast case.
Vintage
MXR
Is based on the same components as the original and it sounds very much
the same.
This now belongs to my son who wanted a red transparent case and knobs
off a Telecaster. Not very Vintage looking but has the Vintage sound.
Test Pedal
(Not shown)
Is a copy of the modified one but with Silicon diodes which give more
distortion but sounds harsh and scratchy, it has a lot more fizz.
This may be converted to the modified spec above as a backup/spare.
Technical
Spec
|
MXR
/ Vintage
|
Modified
1 |
Modified
2 |
Diodes |
2
x 1N4148 |
2
x 1N4148 |
4
x 1N914 |
IC |
LM741 |
TL071 |
TL071 |
Pot
(Volume) |
10
Ohms |
47k
Ohms |
100k
Ohms |
Pot
(Distortion) |
1
Meg |
470k
Ohms |
1
Meg |
Input
Capacitor |
10k |
47k |
47k |
|