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<DIV dir=ltr align=left><SPAN class=817435020-20012022>Hey Todd, there's no need
for an ugly old Lazertran panel. I have shiny, beautiful
Metalphoto-of-Cincinnati panels now. I'm also making Dotcom-format ones
with laser-engraved Dotcom panel blanks. Pictures attached.</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=817435020-20012022></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=817435020-20012022></SPAN> </DIV>
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<DIV dir=ltr align=left><FONT size=2 face=Tahoma><B>From:</B> Todd Sines
[mailto:sines_list@scale.la] <BR><B>Sent:</B> Thursday, January 20, 2022 11:37
AM<BR><B>To:</B> David G Dixon<BR><B>Cc:</B> synth-diy; cheater
cheater<BR><B>Subject:</B> Re: [sdiy] 1-quadrant multiplier with
2164<BR></FONT><BR></DIV>
<DIV></DIV>
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style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: #ffecb3; FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; FONT-FAMILY: Arial, sans-serif; COLOR: #000000; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</FONT></TD></TR></TBODY></TABLE>Ah ha! Found it, can’t say
you made it easy to track down
<DIV><A
href="https://www.modwiggler.com/forum/viewtopic.php?f=16&t=246966">https://www.modwiggler.com/forum/viewtopic.php?f=16&t=246966</A></DIV>
<DIV><BR>
<DIV>Would happily buy one of the Lazertran panel modules from you.</DIV>
<DIV><BR></DIV>
<DIV>I am also building the 185 and 2 285s so you can see I like to get
freaky.</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>Todd</DIV>
<DIV><BR>
<BLOCKQUOTE type="cite">
<DIV>On Jan 20, 2022, at 2:27 51PM, David G Dixon <<A
href="mailto:dixon@mail.ubc.ca">dixon@mail.ubc.ca</A>> wrote:</DIV><BR
class=Apple-interchange-newline>
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<DIV dir=ltr align=left><SPAN class=652112119-20012022>There are now 87 Freak
Shifts out in the wild all over the world, and everyone seems to
be impressed with their performance. Plus, the price is a
measly US $300, which is a fraction of what other Bode frequency shifters
cost. (Bear in mind that I build each one by hand, and each
one takes me about 5 hours, so they are not mass produced.)</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=652112119-20012022></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=652112119-20012022>Hence, not to put too
fine a point on it, but I would say that the Freak Shift is the analogue
design to beat.</SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Todd Sines [<A
href="mailto:sines_list@scale.la">mailto:sines_list@scale.la</A>]
<BR><B>Sent:</B> Thursday, January 20, 2022 10:32 AM<BR><B>To:</B>
synth-diy<BR><B>Cc:</B> David G Dixon; cheater cheater<BR><B>Subject:</B> Re:
[sdiy] 1-quadrant multiplier with 2164<BR></FONT><BR></DIV>
<DIV></DIV>
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style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: rgb(255,236,179); FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; FONT-FAMILY: Arial, sans-serif; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</FONT></TD></TR></TBODY></TABLE>I’m not very dialed in with the
math, but I would say that Harald’s analogue design is the one to beat, and
Don’s was more of a quasi-kludged modular building block that had mixed
results. The math was right but the sound was a bit different, from what I can
tell.
<DIV><BR></DIV>
<DIV>The 185 is basically a dual mixer that combines 2 phase shifters and a
ring modulator that are hard wired as a hopped up ring modulator. </DIV>
<DIV>Daniel (LA67) himself mentions that the Bode / Haible design is an
“easier, flexible, and more modern" route to go.</DIV>
<DIV><A
href="https://modwiggler.com/forum/viewtopic.php?t=211951">https://modwiggler.com/forum/viewtopic.php?t=211951</A></DIV>
<DIV><BR></DIV>
<DIV>As you can see even a smaller clone can be quite costly.</DIV>
<DIV><A
href="https://reverb.com/item/3590031-analogue-systems-rs-240-bode-frequency-shifter">https://reverb.com/item/3590031-analogue-systems-rs-240-bode-frequency-shifter</A></DIV>
<DIV><A
href="http://www.cluboftheknobs.com/pro_c1630.html">http://www.cluboftheknobs.com/pro_c1630.html</A>
[970€]</DIV>
<DIV><BR></DIV>
<DIV>The 285 rev 2, all analogue, does all of the above but puts all of the
above components accessible on the panel to utilize the sections on their
own.<BR>
<DIV><A
href="https://modwiggler.com/forum/viewtopic.php?t=194345">https://modwiggler.com/forum/viewtopic.php?t=194345</A></DIV>
<DIV><BR></DIV>
<DIV>The 285 rev 1 design, based on a Spin FV1 DSP IC is “reasonable”
according to Dave Brown</DIV>
<DIV><A
href="https://modularsynthesis.com/roman/buchla285_fv1/buchla285_fv1.htm">https://modularsynthesis.com/roman/buchla285_fv1/buchla285_fv1.htm</A></DIV>
<DIV>"<SPAN
style="BACKGROUND-COLOR: rgb(255,255,255); FONT-FAMILY: georgia, 'Times New Roman', Times; caret-color: rgb(0, 0, 0)">While
not as good as the original all-analog frequency shifter, the performance is
reasonable and the sound qualities are quite nice."</SPAN></DIV>
<DIV><BR></DIV>
<DIV>Haible’s design is still available, somehow, for sale at Random
Source.</DIV>
<DIV><A
href="https://randomsource.net/haible/vintage">https://randomsource.net/haible/vintage</A></DIV>
<DIV><A
href="http://jhaible.com/legacy/frequency_shifter_fs1a/fs1a">http://jhaible.com/legacy/frequency_shifter_fs1a/fs1a</A></DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>Todd</DIV>
<DIV><BR>
<BLOCKQUOTE type="cite">
<DIV>On Jan 20, 2022, at 1:02 29PM, David G Dixon via Synth-diy <<A
href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</A>>
wrote:</DIV><BR class=Apple-interchange-newline>
<DIV>
<DIV>I suppose that anything is possible, cheater. However, not really
with a<BR>Bode frequency shifter, which is what the Freak Shift
is.<BR><BR>In case y'all didn't know, the Bode frequency shifter is really
just a<BR>trigonometric engine. It realizes the so-called angle sum
and difference<BR>identities, and this gives the frequency shifting.
It will shift the<BR>frequencies accurately over whatever frequency
range that the Dome filters<BR>give accurate 90-degree phase shift, and will
give inaccurate shifting<BR>outside of that
range.<BR><BR><BR><BR>-----Original Message-----<BR>From: cheater cheater
[<A
href="mailto:cheater00social@gmail.com">mailto:cheater00social@gmail.com</A>]
<BR>Sent: Thursday, January 20, 2022 7:25 AM<BR>To: David G Dixon<BR>Cc:
Neil Johnson; synth-diy<BR>Subject: Re: [sdiy] 1-quadrant multiplier with
2164<BR><BR>[CAUTION: Non-UBC Email]<BR><BR>I wonder if it's possible to
build a frequency shifter that shifts higher<BR>harmonics more than lower
harmonics.<BR><BR>On Wed, Jan 19, 2022 at 6:48 PM David G Dixon <<A
href="mailto:dixon@mail.ubc.ca">dixon@mail.ubc.ca</A>> wrote:<BR>
<BLOCKQUOTE type="cite"><BR>I must confess that I've lost the thread of
this argument just a little<BR></BLOCKQUOTE>bit.<BR>
<BLOCKQUOTE type="cite">However, what I like about my approach (which I
have used many times <BR>in many different contexts) is that, in order to
build a nice linear <BR>VCA from 2164, you really need to have a clean 5V
source anyway. I <BR>keep a pile of LM336Z5 for just this purpose,
and use two opamps to <BR>buffer and invert this to get
low-output-impedance +5V and -5V <BR>references on all my multipliers.
If one uses precisely matched <BR>resistors on the inverter, then
one can get those references within a <BR>mV of each other -- the actual
voltage doesn't matter (and it is <BR>usually around 4.90V), but as long
as they are equal and opposite, <BR>then they can be used for precise
multiplication. This is one of the keys<BR></BLOCKQUOTE>to the
precision of my Freak Shift frequency shifter circuit.<BR>
<BLOCKQUOTE type="cite"><BR>I don't really understand how adding a stable
DC value to a signal <BR>increases the noise of that signal. I must
confess that I also don't <BR>care at all about it. My method is the
simplest. You don't have to <BR>pre-condition the incoming signals
at all. The CV signal is <BR>unchanged, and the DC reference levels
are simply summed to the incoming<BR></BLOCKQUOTE>signal.<BR>
<BLOCKQUOTE type="cite"><BR>If you want to change the actual levels, you
can simply change the <BR>resistor values. I do this all the time.
One of the keys to my <BR>one-VCA four-quadrant-multiplier circuit
(of which there are two in <BR>the Freak Shift, made from a single 2164
chip) is to lift and diminish <BR>the CV such that the zero point of the
multiplier is at +5V and full <BR>+/- unity-gain multiplication occurs
between +2.5V and +7.5V. This <BR>gives lots of headroom<BR>-- it
essentially makes it impossible for the CV in the multiplier to <BR>hit
zero at the 2164 control pin (because the incoming CV signal will
<BR>never be anywhere near 20Vpp), which would give a dead zone on the
<BR>multiplication. I achieve this simply by bringing the CV in
through <BR>200k while using 100k on the reference voltages. Of
course, the <BR>signal is now cut in half as well, so I simply double the
feedback <BR>resistor on the I-V converter. As long as all of these
100k and 200k <BR>resistors are within 0.1% of each other (and the 100k
and 200k <BR>resistors don't need to be in a precise ratio -- they only
need to be <BR>precise within their own values), and all incoming signals
are AC <BR>coupled through big back-to-back electrolytics, then the
four-quadrant<BR></BLOCKQUOTE>multiplication is very tight, which is
important for frequency shifting.<BR>
<BLOCKQUOTE type="cite"><BR><BR><BR>-----Original Message-----<BR>From:
Synth-diy [<A
href="mailto:synth-diy-bounces@synth-diy.org">mailto:synth-diy-bounces@synth-diy.org</A>]
On Behalf Of <BR>cheater cheater via Synth-diy<BR>Sent: Wednesday, January
19, 2022 4:23 AM<BR>To: Neil Johnson<BR>Cc: SDIY List<BR>Subject: Re:
[sdiy] 1-quadrant multiplier with 2164<BR><BR>[CAUTION: Non-UBC
Email]<BR><BR>I wonder if it matters that Dave's version will create
theoretically <BR>more distortion on the positive swing of whatever vs the
negative <BR>swing, whereas my version will apply distortion
(non-linearity) more <BR>or less symmetrically... do the numbers show that
it matters at all? I <BR>bet it would matter with some, let's say, crappy
devices.<BR><BR>On Tue, Jan 18, 2022 at 1:57 PM Neil Johnson via Synth-diy
<BR><<A
href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</A>>
wrote:<BR>
<BLOCKQUOTE type="cite"><BR>
<BLOCKQUOTE type="cite">This is certainly true but note also the
importance of zero when<BR></BLOCKQUOTE></BLOCKQUOTE>multiplying. The zero
signal stays zero no matter what you multiply <BR>by. In Rutger's case
that zero is in fact -5V, so the origin of Neil's <BR>graph should be at
-5V signal and zero control voltage. That is why <BR>the level-shifting
solution is so effective and it is also why I <BR>believe Rutger is
correct to call this a one quadrant multiplier.<BR>
<BLOCKQUOTE type="cite"><BR>Yes, this is just a bit of algebraic
juggling.<BR><BR>If we take Dave's approach:<BR>- convert the bipolar
+/- 5V input to a unipolar 0 to -10V input<BR>- add a -5V offset to the
output _after_ the VCA (so no bearing on <BR>the quadrantiness of the
VCA itself)<BR><BR>With a unipolar CV and a unipolar signal ... a
1-quadrant VCA.<BR>And don't forget that as-drawn the linearised VCA is
inverting.<BR><BR>Cheers,<BR>Neil<BR><BR>_______________________________________________<BR>Synth-diy
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