Doc Sketchy's new analog FREQUENCY SHIFTER!

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Dr. Sketch-n-Etch
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Wed May 19, 2021 11:20 am

Well, I'm up to 42 orders, you sons of bitches!
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Thu May 20, 2021 12:22 pm

***** IMPORTANT ANNOUNCEMENT *****

One customer requested (and was quite insistent about) a black panel. I have made some black panels and they turned out quite nice. I haven't drilled them yet, and in fact I'm off a bit later today to buy a hand punch so I can punch the holes. I will post a picture when I get one mounted on a module.

I have also noted that muffdiver wants a black panel. If anyone else wants one, please send me a PM. Thanks!

Also, I'm still waiting for the confirmatory art file from Metalphoto that they have to send for my approval before they can make my panels. I'm not sure why it is taking so long.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Ras Thavas » Thu May 20, 2021 12:29 pm

Thanks Doc, when you get pictures of the regular panel and the black panel could you post them? That might make it easier to decide which color panel we might want.
Dr. Sketch-n-Etch wrote:
Thu May 20, 2021 12:22 pm
***** IMPORTANT ANNOUNCEMENT *****

One customer requested (and was quite insistent about) a black panel. I have made some black panels and they turned out quite nice. I haven't drilled them yet, and in fact I'm off a bit later today to buy a hand punch so I can punch the holes. I will post a picture when I get one mounted on a module.

I have also noted that muffdiver wants a black panel. If anyone else wants one, please send me a PM. Thanks!

Also, I'm still waiting for the confirmatory art file from Metalphoto that they have to send for my approval before they can make my panels. I'm not sure why it is taking so long.

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dcramer » Fri May 21, 2021 1:19 am

Dr. Sketch-n-Etch wrote:
Wed May 19, 2021 11:20 am
Well, I'm up to 42 orders, you sons of bitches!
:lol: :lol: :lol:

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by BlinkyLights » Fri May 21, 2021 2:05 am

Just silver for #29, please and thanks.

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by emojiseq » Fri May 21, 2021 3:06 am

Is rose gold an option?

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Mon May 24, 2021 5:49 pm

emojiseq wrote:
Fri May 21, 2021 3:06 am
Is rose gold an option?
No
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Mon May 24, 2021 5:53 pm

I'm up to 47 orders today. I guess I know what I'll be doing with all of my spare time for the next month or so.

I've got another module I'm going to start hawking soon called the Delta Quadrant, which is a dual multiplier with squish and limiter circuits (there's a video on YouTube of my 5U build from a couple years ago -- go find it!), another stacked-PCB monstrosity also in 12HP, but I'm not quite ready to start soliciting orders for that yet (even though 4 or 5 wigglers have already more or less placed orders). It's also going to be $300 US + shipping.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by ashbashbeard » Tue May 25, 2021 7:51 am

This needs a BIG knob, as is frequency shift tradition!

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by drewfx1 » Tue May 25, 2021 2:34 pm

ashbashbeard wrote:
Tue May 25, 2021 7:51 am
This needs a BIG knob, as is frequency shift tradition!
But for those doesn't the BIG knob always control the frequency of the internal oscillator? Since this doesn't have an internal oscillator that means you just need one of the external oscs you feed into this to have a BIG knob.

Luckily I have one of these in my rack:

Image

:goo:

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Tue May 25, 2021 3:21 pm

Some of us have big knobs and no oscillator.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Tue Jun 01, 2021 2:05 am

Hey Team, I haven't been on Mod Wiggler for several days. I thought I'd post a brief update.

Today my very huge Tayda order arrived which, along with the huge pile of Dome filter resistors I received from Digi-Key a few days ago, completes the collection of all the stuff I need to complete the rest of the Freak Shift orders, and then some. I'm up to 50 units ordered now, and I'm currently working on units 19 and 20. As of now, six customers want black panels, but I have only made two panels, and I still haven't put any holes in those. I ordered a fancy hand punch tool to make very clean and accurate holes in sheet metal, and that should arrive in a few days. Also, my panel-buddy Ian is on vacation, and the Glowforge laser engraver is in his studio, so I won't be able to make the rest of the panels until next week. However, as soon as I have the rest of the panels in hand and can put the holes in them, those units will go in the mail. If you specified a black panel but have not received an invoice, you will very soon -- some of you will effectively be "jumping the queue."

HOWEVER, before you all start asking for black panels, the professionally made natural aluminum panels are scheduled to ship from the manufacturer this Friday, so they will also be arriving soon -- maybe sooner then I get the rest of the black ones made. Of course, as soon as they arrive, I will start getting Freak Shifts in the mail. I have all my boxes and packing shit ready to go -- this is like a proper business, I tell ya!

Lastnight and this morning I Sketched-n-Etched 11 Freak Shift board sets -- that's 55 boards! Gawd, was that ever tedious -- I don't think I'll be doing that again -- I'd rather just make them one or two sets at a time. So, over the next few days I'll be drilling them and installing jumpers and resistors. Tonight I've been sorting my massive haul of Dome filter capacitors (about 2000 capacitors, which all have to be measured and sorted into little baggies in 0.2% increments). I did 500 1-nF capacitors tonight -- I can only do one value at a time, because it is SO tedious, and it kinda does my back in sitting there doing it. Hence, it will take a few days before I can install any Dome filter capacitors, but no worries, because I have a lot of boards to drill, jumpers to cut, and resistors to install. If I can get, on average, two units done per day, then I'll be up to 31 complete Freak Shifts by the end of the weekend.

My goal is to have all of these orders filled within about the next three weeks, so I'll be sending out the rest of the invoices over the next few days. If you still haven't given me your email address and/or full name and/or mailing address, please do so via PM.

Now I think I'm going to quit for the night and go to bed. It's after midnight.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by ashbashbeard » Tue Jun 01, 2021 4:19 am

drewfx1 wrote:
Tue May 25, 2021 2:34 pm
ashbashbeard wrote:
Tue May 25, 2021 7:51 am
This needs a BIG knob, as is frequency shift tradition!
But for those doesn't the BIG knob always control the frequency of the internal oscillator? Since this doesn't have an internal oscillator that means you just need one of the external oscs you feed into this to have a BIG knob.

Luckily I have one of these in my rack:

Image

:goo:
Apologies, I misread the part that it lacks an internal oscillator.

I just like big knobs. :despair:

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by BenB » Tue Jun 01, 2021 4:23 am

Sorry if this is a dumb q or if it's been covered elsewhere, but what are the sum and diff outputs - how do they compare or relate to the signal at the input, and the signal from the main output? And how are they affected by the sum / diff pot?

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Tue Jun 01, 2021 2:03 pm

BenB wrote:
Tue Jun 01, 2021 4:23 am
Sorry if this is a dumb q or if it's been covered elsewhere, but what are the sum and diff outputs - how do they compare or relate to the signal at the input, and the signal from the main output? And how are they affected by the sum / diff pot?
The SUM and DIFF outputs are the two outputs of the Freak Shift. A frequency shifter generates single sidebands -- one shifted above the signal frequency and one shifted below the signal frequency. The SUM output is the down-shifted one, and the DIFF output is the up-shifted one. Here's a diagram of the mathematics of a Bode frequency shifter to demonstrate the concept:
BodeFS.png
SUM it the top output, and DIFF is the bottom output.

The OUT output is the buffered output of the manual crossfader (SUM/DIFF).

Note that the Freak Shift does not have a Quadrature Oscillator, but instead has a second 90 deg PDN (Dome filter) to convert any audio or LFO signal into a quadrature pair.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Tue Jun 01, 2021 2:10 pm

UPDATE: I have sent Paypal invoices to the first 40 people in the queue, with the exception of chvad (No. 3) who never gave me his (or her) email address.

If your queue position is 30 or below, then you can expect a Freak Shift around the middle of June. If your queue position is between 30 and 40, then you can expect a Freak Shift around the end of June. If your queue position is higher than 40, then I have not sent you a Paypal invoice yet, but you can expect a Freak Shift around the middle of July.

I have all of the boards made for the first 30 units, and I have the first 18 units completed (but no panels), units 19 and 20 half done, and units 21 to 30 are just undrilled boards. I will complete units 19 and 20 today, and I expect to have all 30 units complete by the time the panels come, which should be late next week. Also, next week I will make the rest of the black panels (at least, that's the plan).
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by zengomi » Tue Jun 01, 2021 5:07 pm

Thanks for yet another update, Doc.

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Tue Jun 01, 2021 8:49 pm

I just got my 50th order tonight. I think I might be the only "manufacturer" still making modules right now, because all the parts I need for this thing are still available. Evidently, any module requiring a microcontroller is stalled. I just learned that some of the "specialty" opamps used in some modules will be unavailable for the next 9 months. I guess it pays to limit ones BOM to parts that are very common. I've always tried to design everything with the barest minimum of different parts.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by McIntosh » Wed Jun 02, 2021 12:40 am

Could this be an interesting development for synth designers to get creative with what is lying around. I work as a cabinet maker and I have had problems getting material forcing me to get creative..
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dr. Sketch-n-Etch » Wed Jun 02, 2021 2:10 am

It's not so much "what's lying around" as "restricting use of exotic parts." For instance, I have very little patience for comparing one opamp to another, and I refuse to pay a lot of money for fancy chips. I have yet to find an application for an opamp where the humble TL072/4 doesn't perform admirably. I doubt very much that anyone without fancy equipment could tell the difference whether a $1 opamp or a $10 opamp was used in an audio path. If I need a certain spec (such as low input current for sample-and-hold buffers) then I will choose a more appropriate opamp. For modular synth, there is no audio signal that a TL072/4 won't reproduce with more or less absolute fidelity.

For voltage control, I use the 2164 quad VCA. I started out using the LM13700 dual OTA, but fairly quickly abandoned those in favour of the 2164. It works perfectly and does everything I need it to do. The only drawback of using it is that it absolutely must terminate to virtual ground, which can be a bit inconvenient, particularly for some filter designs. However, it hasn't really been a problem, since I've designed about half a dozen filters around it. I also use it as a temperature-compensated exponential converter in VCOs, and my VCOs are some of the most accurate out there. I also use it as a balanced modulator, and I have a clever circuit for getting two complete balanced modulators out of a single 2164 chip (which I have used in the Freak Shift) -- unlike the MC1496, it requires very little trimming (although I do hand-select the resistors in that circuit). In fact, it turns out that the key to accurate single-sideband generation in the Bode frequency shifter is AC-coupling of the quadrature signals going into the multipliers -- they don't talk about that in Electronotes -- I had to discover that little gem myself.

There are literally no other chips in the Freak Shift. The only other semiconductor is a 5V source (LM336Z5). Other than that, it's just a vast pile of resistors and capacitors. For the Dome filter capacitors, I limit myself to power-of-ten values and then customize the resistors to get the desired RC factors.

I figure that with TL072/4, 2164, and one or two other things, I can design just about anything.
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by McIntosh » Wed Jun 02, 2021 5:21 am

Simplicity is beauty, I love this kind of approach.
I agree about exotic parts I have abandoned exotic woods for good quality pine, anyway back to dome filters...
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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Dcramer » Wed Jun 02, 2021 8:43 pm

I love that this thing has become such an underground hit 🙀

I’ve sent a few customers your way Doc, strangely enough some members have are under the illusion that I’m actually smart enough to build these things! :foul:

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by Bernie Hutchins » Wed Jun 02, 2021 8:50 pm

Dr. Sketch-n-Etch » Wed Jun 02, 2021 2:10 am said in part:
“…….it turns out that the key to accurate single-sideband generation in the Bode frequency shifter is AC-coupling of the quadrature signals going into the multipliers -- they don't talk about that in Electronotes -- I had to discover that little gem myself. …….”

Any mention of a need of removing the DC components is OBVIOUS (high school trig), clear to most everyone here, and I suspect we did cover this if one looked carefully. This removal of DC from the quadrature signals can be done by trimming (best) or by AC coupling (which is, after all, HP filtering and subject to the resulting magnitude and transient responses).

I suspect that achieving the best sideband separation is more a matter of addressing differential phase error (which I believe we reported) and/or well-trimmed sum/difference circuitry.

What analysis (like “classical sensitivity”):
http://electronotes.netfirms.com/EN195.pdf
(see pp 4-10) led to your purported discovery?

-Bernie

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by transferpoint » Wed Jun 02, 2021 9:33 pm

Dr. Sketch-n-Etch wrote:
Tue Jun 01, 2021 8:49 pm
I just got my 50th order tonight.
Did you get my order request by chance? Wasn't sure if it actually sent :hihi: haha

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Re: Doc Sketchy's new analog FREQUENCY SHIFTER!

Post by rediris » Wed Jun 02, 2021 11:56 pm

Just sent a PM/email, not sure if you received it. Thank you!

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