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It's been a while...  Hope all's well with everyone.  I'm somewhere between "still building" and "retired", with no good idea of what "retired" might actually mean...

Thought I'd share an easy mod with you.  I discovered it by putting the wrong size of capacitor in a build and ended up with something very different that I liked better than the correct circuit.  Maybe some of y'all will enjoy it, too. 

In the Foxx Tone Machine / Wolfshirt, there is a 1n capacitor between the base of Q1 and emitter of Q2 (C3 in the Wolfshirt schematic).  Instead of 1n, make it 100n.  The result doesn't really remind me of any other pedal circuit I can think of off the top of my head.  Dark and nasty OD with an octave?  I only tried it with single coils, not humbuckers yet.  It might get pretty heavy with humbuckers.  I have it on a switch to go between the original 1n or adding the 100n in parallel to it.  Probably the easiest way to try it is to temporarily tack the 100n onto the back of the 1n to give you 101n.  To really do it right, perhaps the tone control should be tweaked a bit, but it's OK enough as it is that I've lost a couple afternoons with nothing much to show for it other than a smile.  "Beware of the dark side."

I have no affiliation with them other than being a happy customer for several years, but Kinman pickups out of Australia are really good.  They started with a variety of noiseless strat and tele pickups years ago when I first started buying them.  Now they have humbuckers, bass, P-90s, etc.  They also provide a variety of no-soldering wiring harnesses with the correct pots, switches, caps, pickup covers, pickguards, etc.  They are really helpful with pickup/harness selection, as well as all facets of installation and adjustment.  Their website can come across a bit "hype-y", but the products really are that great.  I've tried several of their strat and tele pickups and have been extremely happy with all of them.  I initially found them because I like single coil sound but had a serious noise problem.  They took care of my noise problem, but also sound great.  I haven't tried their humbuckers yet - can't get past the single coils.  Would love to try their P-90s.  I'm thinking of buying another guitar just to put some of their P-90s in it.  That's how happy I've been with their tele and strat pickups.  Even if you don't purchase from them, their website has loads of great information to check out.

Sorry for the slow response.  I forgot to turn Notify on for my posting...

Just my opinion, the API 500 design might be a good starting point.  But it didn't match up for what I wanted to do, or perhaps more accurately, how I wanted to do it. 

An effects chain often has more than just a straight-thru path.  There are loops, ABYs, amp selectors, order swappers, stereo effects, etc, all of which complicate the routing of the signal.  If you are using a bus-based approach, you can manage all that with bus controllers, addressing, routing, etc – through software.  Although I'm a software professional of a few decades, I'm going through my "tech rebellion" years now – I didn't want any programming or tech complications.  My design is just simple analog plug and play for the signal path(s), power, and switching, with a physical structure to hold it all together. 

You can definitely have a bus/backplane type of solution, but it'll probably be digital and require a good amount of software development, requiring an operating environment and central control module.  Aside from the old debate about digital vs analog, there's nothing wrong with going that way.  It's just a different approach with different problems requiring different tools.  I expect there are chunks of design and software buried in those digital multi-effect units that do pretty much all of that already - sort of an existence proof that it can be done.  At the conceptual level you might just be substituting digitally controlled effect cards/modules for software models of those effects.  You could probably even make the cards/modules analog, but you'd have to figure out a power and switching design to go with it.  If you wanted to do all that with the API 500 hardware specifically, then you would be starting with hardware constraints on your overall design already in place.  I don't know enough details about the API 500 to guess if that would be a great jumpstart, something you'd be constantly battling with, or something in between.  I also don't know if it is an open design or something you'd have to figure out, or any intellectual property issues (patents) you might have to avoid.  If I were going that direction in the future, I'd look more closely at API 500, multi-effects units, modelers, synthesizer technology, and everything else I could think of like that to get some ideas, see what works well/poorly, and then design my own specifically for this purpose.   But that's the software guy in me peeking out, and we're notoriously infected with the "not invented here" disease and always assume we can do a better design !!!  In general, I think there's space for analog effects with digital control, although it might take a while (and $$$) to pull it all together in a systematic way with digital switching.

Funny thing is that some people take a quick glance at my stuff and think it is API 500 series gear, some other "studio stuff", surplus NASA equipment, or an old missile control system left over from the Cold War days.  This is especially true at the guitar shows I've attended because I take a big pile of modules to those shows for people to try, and that can look intimidating.  It's the rough equivalent of maybe 15-20 normal pedalboards.  There are some pictures of that "Big Stack" of almost 200 modules on my Facebook page "GerltTechnologies".  It does work fine in a studio, and looks a little like API 500 series or other studio gear, but they have nothing in common beyond the first-glance appearance and general "racked audio components" concept.  Even all the metalwork is my own custom design and fab.

If you are in the Dallas area, I'll have a booth at the Dallas International Guitar Festival in Market Hall on May 1 - 3.  Stop by to say "Hi" and check it out.

Thanks for taking a look guys, and especially for the well wishes.  I know if it "only" took an idea, dedication, and a lot of hard work plenty of people would be making it in the effects business, even with a very loose definition of what "making it" might mean :^) 

Since I don't have a pretty face, rock star connections, or rich relatives, I'll gratefully take every bit of good luck sent my way.  Thanks!

Hi, everyone. 

I used to hang out here in a small way some years ago, but got really busy and haven't had much spare time to drop in for a long time.  This is a great group and one of the best forums anywhere on the 'net, so I hope to be able to spend more time here as I come up for air after being really, really busy for a long time.  The purpose of my post is to make it clear that I now have an affiliation to disclose.

Many of you know that building pedals can go, well, shall we just say "beyond what you first intended".  Perhaps even beyond that.  That's what has been keeping me busy for some time now.  Somewhere along the way, I had an idea about building pedals that grew and morphed into something bigger than I originally planned.  I'm now in the early stages of launching that idea as a business.  What makes what I'm doing a bit different from most others is that I'm only developing rack effects, no pedals.  You can check it out at www.gerlttechnologies.com.  I know I don't need to explain it to this group – you'll get it right away, everyone does.  I've taken my gear to a few guitar shows to get early feedback, and am happy that the feedback has been overwhelmingly positive from players, about both the idea and the sound.  Would love to hear your comments as I begin to spread the word.  The website needs work, but basic info is there, except product videos – still have to get going on those. 

Anyway, that's it.  I hope you find it interesting.  This is one of my first public postings about what I'm doing, and it seems only natural to do it here where my effects-building interest began to develop into a serious condition that probably needs some sort of treatment, if it is not already too late.  If any of you are in the Dallas area, I'll probably be at the Dallas International Guitar Festival again this year in May, although I have some scheduling issues to sort out first.  If you're there, stop by the booth to check it out in person and say "hi".  I have some pics from the shows I've attended at my Facebook page "Gerlt Technologies".  I don't know what's in store for me, but I've really been enjoying what I'm doing, and being able to share it with others.

Cheers,

Bill

Your first comment got me thinking about something separate, but related...

You said I might have left the gain trimmer connected to ground instead of power.  Since I don't have a gain trimmer, I'm guessing that refers to the gain trimmer in the earlier DEM models (v1 – v3 at Metzger's site).  If I built that version, would I still want to add the pullup resistor to V+ on the output pins and the NPN buffer, followed by the gain trimmer connected to ground to get a nice bias level for the opamp?  Or skip the buffer and hook the gain trimmer to V+ for pullup on the output pins?

Yup, 2N5089. 

Thanks for quickly kicking me out of my rut.  In a previous life, I was a software engineer.  Debugging software and electronics often benefit from some of the same skills and approaches, but once in a while "software thinking" simply doesn't work in the world of electrons.  Like this time.  And when you're thinking the wrong way, it doesn't really matter how hard you think :^)

OK - so that's my first problem.  I'm testing the wrong way with my output pins floating right now.  Now I have to 'fess up about what started me down that path.  When I moved some stuff around on the layout of the new board, I reconnected to bias power instead of V+ after the resistor on my output pins, plus I was trying to remove my mods after that point from the problem by not populating that part and introducing unknowns. 

So now I'm guessing that my only problem is that incorrect connection to bias instead of V+ (which I disconnected since it was wrong).  Then I inadvertently created an insurmountable fake problem since all subsequent measurements were taken with no V+ on the output pins    I'll never get anywhere that way, right?  I tricked myself into thinking the problem was before the output pins, not after.

For the record, barring the errant V+ connection, my MN3007 is implemented as it is in Current Lover, except I tied the output pins together and used a single resistor on the combined output.  My other mods are optional things which I can jump through or around to get things going.

If that's correct, then I'll see if I can hack my board to get to V+ instead of bias power in an ugly way.  If that clears the problem, then I'll get new boards with that fixed.

Does that sound about right?

Oops - I think I hit a "tab" key or something while I was trying to make that more readable and it prematurely posted on me.  Other than messy formatting I think the info is OK.

Hi Scruffie, and thanks for having a look.

The DEM in question is the late 90's v5.  Here's a link to the schematic I used (except the LFO) at Ralf Metzger's Electric Mistress site: 

http://www.metzgerralf.de/elekt/stomp/mistress/images/deluxe-electric-mistress-v5-schematic.gif

The only differences I have from the front end of this are: 
using 15V regulator on 18V power feed for about 14.5V instead of 12V, and instead of the (2) 1M resistors to the bias voltage on the input, I have a 100K going to my bias voltage trimmer that lets me adjust from 0V to 14.5V.  Component values all the same.  The output of the second opamp stage goes directly to the input pin on the MN3007.  This is what works on my previous builds on my original boards. In my new board I added the 100n cap and bias setup like Current Lover has on the input to the BBD, but it doesn't change my problem if I jumper that cap and remove the bias. 

Right now on the board I don't have anything populated past the BBD output pins, so it is just the front end and MN3007 - no mixer, output, gain trimmer, feedback, etc.  Just the two opamp stages feeding the MN3007.  Trying to keep it simple and isolated.  Connections to the BBD are as described above.  I think the LFO is the same as the Current Lover.  I think you and I traded messages about Electric Mistress LFO's a long while back and I settled on that one.  I've used it successfully ever since.

I'm guessing I've done something bad when I added the ground planes to the board, since that is the only change from the working board to the partially populated, non-working board.  I have also tried populating everything after the BBD, and that works as well as it can without wet signal coming out of the BBD.

Hey, flanger and MN3007 experts out there.  I've goofed something up and am stuck trying to find the fix.  I'm looking for any hints on where to go next.

I have been debugging on this for days, so I have tried many, many things and have a lot of interesting notes and details I could share.  But I keep ending up stuck at the same place, so I need to get kicked out of my rut.  I'll try to leave out as much as possible here but the specific details I'm providing are all a part of my problem.  Feel free to ask anything else.  I will not be offended - embarrassed quite possibly, thankful most definitely, but not offended :^)

First, I'm building a Deluxe Electric Mistress.  I have my own boards.  The LFO is on a separate board from the main FX circuit.  I have built a few of these recently, and they all worked first time.  Then I made some board changes to try some mods in the mixing and output section.  While I was at it, I switched from using a single bias trimmer for opamps and BBD to separate ones, adding the requisite bias resistor, dc blocking cap, etc.  I also added ground plane pours on both sides of the board.  Now, when I build the board, I get no MN3007 output no matter how I try to bias it.  I also built a new LFO board to go with the new FX board.  All I did on the new LFO board was add a CLR and blinking LED, and ground plane pours on both sides of the board.  Those are the only changes between the working and non-working boards.

Since I have working versions using earlier versions of the board, I can try out MN3007 chips.  I am using known good MN3007 chips that work fine on other boards.  I can also switch to one of my earlier known good LFO boards, to eliminate the entire new LFO as a problem.  However, my new LFO board does work fine with an earlier FX board.  An earlier known good LFO board does NOT make my new FX board work.  Just FYI, the LFO is used by some Electric Mistress or Deluxe Electric Mistress, I can't remember which.  It is very similar to the one in Current Lover, and has the CD4049 on the end to drive the BBD.  And the timing cap is adjusted to get the speeds I want for my MN3007.  Anyway, because of this info, I believe I can say that neither the LFO or MN3007 are the problem.   

Here's the data that has me stuck.  These are the measurements taken directly on the pins of the MN3007 in my non-working board.

                pin 1 (ground):                  14.50V 
                pin 2 (clock 1):                   aprox 8.0 – 9.5V as the LFO varies, with Filter Matrix switched to manual, I get 30KHz at the extreme slow end and 340K at the extreme fast end (sometimes I go as wide as 25-440K).  I can hear the clock throbbing.
                pin 3 (input):                      my bias lets me adjust from 0v to 14V (I measured it).  I have clear, strong audio signal at this pin
                pin 4 (Vgg):                         goes to a 10uF cap to ground (oriented correctly), and usually has about 1.0 – 1.5V, sometimes as low as a few 100 mV if I've been measuring it and discharging the cap
                pin 5 (V+):                           0V
                pin 6 (clock 2):                   identical to pin in all measurements
                pin 7 (output):                   0V
                pin 8 (output):                   0V

When I search for output signal while adjusting the bias, once in a great while I get a little heavily distorted clock noise when the bias is somewhere near 4.5V.  But it goes away very quickly, like it is being drained to ground or fading out somehow.  I cannot make it happen twice.  Once it stops, then I can't get it back until "later" – letting it sit, power cycling, something will eventually "reset" it and I'll hear it again briefly.

This always reminds me of the new ground planes I added.  I've gone back and visually followed every trace and hole looking for ground plane issues on the FX board (new unpopulated one).  I've even done continuity checks on every single hole.  All seems well.  On my board, there is a trace connecting pins 7 and 8, which then goes on to the rest of my circuit through a cap.  Not only is there no sound at pins 7/8, there is nothing at or past the cap (taking all my new board mods out of play except for the biasing and ground plane changes).  Right now I am testing a board that has nothing populated past that cap. 

Being suspicious of a bad ground plane connection, I tried 2 things.  First, I removed the MN3007 completely and put a jumper from pin 3 (input) to (pin 7).  I get audio at pin 7 and after the cap.  The board is not grounding it out.

I also reseated the MN3007, but with pins 7 and 8 bent out so they did not seat in the socket.  Then I tried to bias.  Almost, but not quite, the same thing happened as before.  I actually got audio on the output pins very briefly as I turned the bias voltage down toward 4.5 – 5V.  But it faded away just like the "distorted clock noise" did with those pins fully socketed.  Could be a fluke, or it could be that whatever is happening just happens a little faster when those 2 pins are socketed.  I expect the "heavily distorted clock noise" is really faint, heavily distorted audio.

I also replaced the 10uF cap from Vgg to ground with a jumper.  Since I've done that, I haven't heard even the little bit of fading clock/signal noise that I used to have.  But I didn't always have that noise before, so this may not mean much.  The only difference I noticed after this change is that instead of 0V on the output pins, I have around 150mV.  But that may be coincidental.  I think I've seen tiny voltages like that from time to time, which keeps me thinking that I'm somehow draining to ground somewhere.  But that somewhere seems to be between pin 3 and pin 7/8...

I also backed out my biasing change.  I took out the resistor on the input line to my bias trimmer and replaced the DC blocking cap I had added with a jumper.  My bias is now coming in on the output from an opamp, as it does in my working board.  No difference at all, other than which biasing trimmer I use to search for signal.

Also, note that all my MN3007 measurements (except the missing output on pin 7 and pin are identical to measurements I've taken from one of my working builds on the previous board version.

I've built a lot of pedals, so I'm careful and reasonably proficient, but still have much to learn.  I've checked all my usual methods of goofing up, many times, carefully.  I've removed/replaced components, reflowed solder, looked for bridges/bad joints, and lots and lots of debugging.  I've even built multiple of these non-functioning boards to further reduce the chances of soldering errors and bad components.  I'm only populating the minimum part of the circuit needed to test for MN3007 output.  Everywhere I have probed or tested, I seem to have good/expected values with the exception of those two output pins.  This is true for each board and experiment I've tried.  I haven't found anything wrong anywhere.  That just means I'm overlooking or misunderstanding something, of course.  I've even been suspicious of my probe, and tested it :^)

So that's the hole I'm stuck in.  Everything seems good for my known good MN3007, yet I can't get it to give me any output.  Everything feels like some sort of grounding problem, or just a lack of effort on the part of my MN3007 :^)  I'm sure there is something I'm not measuring that matters on the MN3007 pins.  What could I look for there that would shed light on why the MN3007 refuses to pass signal?

Note that the makers of the DCA55 and DCA75 apparently thought it would be a good idea if they used different transistor test parameters for those two units.  The DCA55 results are more comparable to other methods and will give you results in line with the rules of thumb for hfe and leakage in various fuzz circuits, etc.  The DCA75 tests with higher parameters that will generally give you higher HFE and higher leakage results.  But you cannot extrapolate forward or backward between DCA55 and DCA75 hfe or leakage results.  It depends on the range of HFE and leakage of the transistor under test, transistor model, etc.  With the DCA75, you can change the test parameters and graph the results, which is cool.  But you have to be hooked to a PC and take the extra time.  Maybe not what you want to do when you are grading a batch of transistors or trying to pick some for a build. 

I bought a DCA75, not realizing that.  I had problems when I would buy graded transistors, and when I was doing builds.  Once I figured out what was going on, I switched to a DCA55 and things are better now.  Of course neither are measuring at the circuit levels, but then the methods used to devise the rules of thumb we have probably don't either.  It's all just guidelines to get you in the ballpark.  But the DCA75 results are less compatible.

I contacted Peak Atlas about this oddity that their meters give different answers, by design.  Also made several suggestions on how to easily make the DCA75 more compatible.  They were polite, perhaps interested, but that was months ago and I haven't heard from them again.

I use my DCA all the time for diodes and transistors.  Never have to look up or remember pinouts!

I use an LCR meter for measuring resistors and caps, not my DCA.

If you qualify for student pricing, then this might get close to your price range:  http://store.digilentinc.com/analog-discovery-100msps-usb-oscilloscope-logic-analyzer/. 

I'm a scope noob myself, and infrequent user, but this one works pretty well for me.  Plus I didn't have to also buy a signal generator I was looking for at the time.  I run it on my laptop.

I'm not a whiz on BBD stuff, so I might be in the weeds on my parallel thinking.

If you put them in parallel, they would probably be just a tiny bit off from each other.  I thought that might make it a little more "lush" or "swirly" when you put them together.  Could take one clock output from one and the other clock output from the other one (maybe this is the electric mistress way), or just mash all 4 channels together.

Yeah, been beating on this one for a while now.  I was already thinking of switching to the one used in the Deluxe, which seems to be about the same as the one in Current Lover.  Plus I'll have a clock trimmer and the world will seem more normal 

Have you tried a parallel MN3007?