owlexifry
Well-known member
the MXR phase 90 build i did few weeks ago was my first phaser experience.
wasn’t expecting to enjoy phasers this much.
and then @jimilee dropped anecdotes of stacking phasers and notes of leslie / rotary sounds… (gish is absolutely my favourite SP album)
so i knew i had to try and build something else…
-vero layout-
just looking at this layout got me all excited before i even knew what this was, sounded like, or had even heard of a Mu-Tron..
never done a circuit with LDRs before.
35 jumpers. 70 track cuts. 6 ICs. (well, x7 if you include the chargepump...)
heck. this is the biggest vero board i’ve ever done.
bit of a squeeze...
(ran out of dymo strip last night, still yet to apply 'in' and 'out' labels...)
first power up:
- genuine tayda-sourced ICL7660S: - hi freq noise
- swapped for a TC1044SCPA - hi freq. noise gone
- then i noticed i was getting some ticking.
i was almost okay with this, but then i noticed it was ticking in bypass as well!!
for me, noise in bypass is absolutely not acceptable.
pondered this for a bit. had done all the right things, used a low current IC for the LFO (TL082) etc.
then i had a lightbulb "guess what, when you use cliff jacks, none of the ground circuit (or any jack sleeve) has any continuity to the enclosure (= no shielding)"
so i loosened up the input jack, stripped a wire end, snuck it in there, so that the wire makes contact with the bare surface of the drilled hole, tightened up the jack, wire secured firmly. then soldered the other end to the star ground (at the input jack).
result - all noise completely gone
- then i actually got to play the thing...
at first, when playing a slow rate, my impression was that the phasing pattern was weird/wrong/'lop-sided', and perhaps i had poorly selected the LDRs, or the LFO was 'off'.
i twiddled with those trimmers for quite some time, and i just couldn't get it sound like what i thought was 'correct'.
in my mind, the phasing pattern appeared to sound like this:
(my perception was that the "downward" phasing was moving at a much shorter/quicker duration than the "upward" phase)
as i pondered, i thought "ohh maybe it's the LFO", "maybe that 470n cap (which actually measured at 490n) isn't close enough to the target value"
- so changed the '490n' cap to a piggybacked pair of 390n+82n that i had on hand (measured 475n).
of course this changed bugger all.
i then felt even sillier after confirming this with a very useful link/tool provided by @Chuck D. Bones on his LFO thread:
LFO triangle wave generator
then i spent a lot of time reading every "Phase II" thread on this forum, and threads with the 'LDR' in the subject line, in an attempt to understand them a little bit more.
- so last night i pulled out all the LDRs and re-measured my batch of 12.
- essentially selected the closest group of 6 by measuring resistances of each LDR under same conditions, and then varying the lighting at each stage of selection (bright, warm, low light).
Unsure if this actually did anything significant.
Confirmation bias would have me believe that the phasing sounds more 'balanced' now. I really don't know.
anyway, here's a quick demo I did last night before dinner:
(starts off real slow, then fast, then medium at the end)
wasn’t expecting to enjoy phasers this much.
and then @jimilee dropped anecdotes of stacking phasers and notes of leslie / rotary sounds… (gish is absolutely my favourite SP album)
so i knew i had to try and build something else…
-vero layout-
just looking at this layout got me all excited before i even knew what this was, sounded like, or had even heard of a Mu-Tron..
never done a circuit with LDRs before.
35 jumpers. 70 track cuts. 6 ICs. (well, x7 if you include the chargepump...)
heck. this is the biggest vero board i’ve ever done.
bit of a squeeze...
(ran out of dymo strip last night, still yet to apply 'in' and 'out' labels...)
first power up:
- genuine tayda-sourced ICL7660S: - hi freq noise
- swapped for a TC1044SCPA - hi freq. noise gone
- then i noticed i was getting some ticking.
i was almost okay with this, but then i noticed it was ticking in bypass as well!!
for me, noise in bypass is absolutely not acceptable.
pondered this for a bit. had done all the right things, used a low current IC for the LFO (TL082) etc.
then i had a lightbulb "guess what, when you use cliff jacks, none of the ground circuit (or any jack sleeve) has any continuity to the enclosure (= no shielding)"
so i loosened up the input jack, stripped a wire end, snuck it in there, so that the wire makes contact with the bare surface of the drilled hole, tightened up the jack, wire secured firmly. then soldered the other end to the star ground (at the input jack).
result - all noise completely gone
- then i actually got to play the thing...
at first, when playing a slow rate, my impression was that the phasing pattern was weird/wrong/'lop-sided', and perhaps i had poorly selected the LDRs, or the LFO was 'off'.
i twiddled with those trimmers for quite some time, and i just couldn't get it sound like what i thought was 'correct'.
in my mind, the phasing pattern appeared to sound like this:
(my perception was that the "downward" phasing was moving at a much shorter/quicker duration than the "upward" phase)
as i pondered, i thought "ohh maybe it's the LFO", "maybe that 470n cap (which actually measured at 490n) isn't close enough to the target value"
- so changed the '490n' cap to a piggybacked pair of 390n+82n that i had on hand (measured 475n).
of course this changed bugger all.
i then felt even sillier after confirming this with a very useful link/tool provided by @Chuck D. Bones on his LFO thread:
LFO triangle wave generator
then i spent a lot of time reading every "Phase II" thread on this forum, and threads with the 'LDR' in the subject line, in an attempt to understand them a little bit more.
- so last night i pulled out all the LDRs and re-measured my batch of 12.
- essentially selected the closest group of 6 by measuring resistances of each LDR under same conditions, and then varying the lighting at each stage of selection (bright, warm, low light).
Unsure if this actually did anything significant.
Confirmation bias would have me believe that the phasing sounds more 'balanced' now. I really don't know.
anyway, here's a quick demo I did last night before dinner:
(starts off real slow, then fast, then medium at the end)
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