Tag Archives | relay

Introducing Limelight True Power Bypass

Coldcraft Effects is proud to announce our latest update to the exceptionally clever True Power™ Bypass system: Limelight™ Bypass

The Limelight™ system simultaneously allows momentary bypass and standard latching bypass without the need to switch between exclusive modes.  Operation is simple and intuitive.  If the footswitch is held for 1 second or longer when enabling the effect, it responds as a momentary switch, turning off upon release.  Otherwise it is latching.

Other key features include:

  • True Power™ bypass – should the pedal lose power, it reverts to true bypass.  This includes the EchoVerberator, which has a buffered bypass with trails when powered.
  • Quiet, reliable relay bypass –
  • Opto-FET muting – silent
  • π-filtered power – no noise gets in, or out.
  • Sophisticated Reverse and AC Power Protection

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Anatomy of a Coldcraft Product

As I was building up the first batch of Cascade MkII Overdrives, I took some quick pictures along the way to demonstrate what goes into the construction of each of our products.  Every Coldcraft product sold after January 2013 features the new soft-touch relay bypass.  The Bypass system was designed by Peter of VFE Pedals, and Jack of Jack Deville Electronics aka Mr Black Pedals.  Hows that for some heavy hitters?

DSC_0020Now here’s the skinny.  All our our 2013 products are built using 2 independent circuit boards.  The main effect board is unique to each product and features board-mounted Pots (knobs), trimmers and switches.   This board (dark purple) holds all the circuitry needed for the effect, save for some power filtering and bias voltages.

The 2nd board is the Bypass/IO/Power board (light purple).  This holds the board mount jacks, relay, micro-controller and power filtering and is common to all of our products.  Certain aspects of the board can be customized to provide for different power requirements of some effects.

DSC_0021Here’s a batch of Cascade MkII enclosures about to be assembled.  Starting from the pre-populated PCBs above, the main effect board is first mounted into the enclosure.  The LED is added (and mounted into the Lens), and ribbon cables are soldered to the main effect board.

Lens?  What’s a lens for?

If you look closely at our products, you can see that we aren’t using those big, chrome bezels for our LEDs.  I’ve used them in the past and I just find them to be bulky, expensive and a bit primative.  What I’ve opted for instead is called a LED lens.  This nearly flat plastic piece is inserted in the LED hole, secured with a little hot glue and the LED is firmly locked into it before being soldered to its board.  This lens actually spreads out the light from the LED whereas the bezels tend to reflect and focus it upwards.  I like them.  It also lets us use white LEDs and color lenses if we wanted to.

No back to that ribbon cable.  What’s that about?

DSC_0022As you can see in this next picture the main effect PCB has been installed.  The board is held in by the three 16mm board mount pots, and the alignment is fixed with the LED, and additional 3 trimmers/switches.  There’s also those little ribbon cables sticking up.  Those ribbon connections carry the input/output, LED, 9v, Bias and ground connections between the two boards.  By mounting them first to the main effect board, subsequent assembly is made so much easier.

DSC_0023From here, the Bypass board is attached, upside down, to the ribbon cables.  This allows the 2nd board to simply be “folded over” into place, and secured using the audio jack nut things.  Yes, I said nut things.  Not really sure what to call them.

You may notice the 2 orange wires already soldered to the Bypass board.  These are the only two wires that must be stripped and soldered in this entire pedal.  Stripping and soldering wires is a huge time killer when assembly compact guitar pedals.  It is also the number one area where mistakes are made during production.

DSC_0024Previously, Coldcraft products were made using 3PDT mechanical switches and wiring boards.  The boards minimized wiring mistakes, but they are just as time consuming as wiring without them.  With the dual board system, final assembly is a breeze.  Tonight, I took 8 pedals from empty to fully assembled in less than 90 mins, including break time.  The finished products are ready for testing, numbering (inside back cover) and knobs!

So there you have it.  This batch of Cascade MkII Dual Stage Overdrives will be exclusively available at Chicago Music Exchange in, you guess it, Chicago, IL.  Check them out!

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The Case Against True Bypass – Revisited

You’ve seen this argument many, many times.  Hopefully, my peers who have written about this before me have convinced you that the revered 3PDT stomp switch, the “True Bypass with LED” savior is really just a bad idea.  Mechanical parts fail, and they fail way before electronic components.  Things wear out and its just how it works.  When it comes to signal switching in electronics, electronically controlled relays present a much more robust solution than simple mechanical stomps.

So dig this, the more complicated the mechanical switch, the more moving parts it has, and the lower the mechanical life expectancy should be.  The best of the best Single-Pole Carling Switches are rated at 100,000 cycles.  You can bet your ass that a run-of-the mill triple-pole switch comes doesn’t even come close.  Possibly within factor of 5, maybe 10 of that, meaning 10,000 cycles. Total shit.  And that’s a statistical figure, with a BIG spread because in the real world, shit breaks, a lot.

Now dig, the Panasonic TQ2-5V relay used in Coldcraft products, and by many colleagues in the music business is rated at 10^8 to (10^7 minimum) cycles.  That’s 10,000,000 activations, MINIMUM.  The MOMENTARY single-pole switch used to activate the relay will wear out before the relay gives up on you.  Unfortunately, relays can still cause switch POP, or audible clicking when used, but luckily, the same logic controls that switch the relay can be used to silence or quiet the switching action.  This is the basis of our bypass system and others including the Jack Deville-designed “Clickless True Bypass” now available at Mammoth Electronics.

Now the problem of reliability has been solved, dare I say its been obliterated.  However, there’s one more thing to consider, and that is Contact Voltage.

What the F is Contact Voltage?

Well, anytime there is a mechanical connection, there is a resistance present because the connection is imperfect.  Maybe the surfaces are rough, possibly oxidized, corroded or just don’t make great contact.  When a voltage is applied across the contact (AKA your guitar signal), the resistance creates a voltage drop across it, known as the Contact Voltage.  We already know that relays are sealed from the outside dirty world (read: your dirty shoes, beer-soaked bar floors, and worse).  The contacts inside the Panasonic relays are made of Ag and Au (Silver and Copper), two of the most conductive metals in town.  Contact Voltages inside a relay will be very, very small, but what else is involved?

Jacks.

Yes, every pedal has 2 jacks, and requires 2 plugs.  So lets say you have a modest pedalboard of 10 true bypass pedals.  If you were in the know, and purchased effects from VFE Pedals, Dr Scientist Sounds, and the like (that includes Coldcraft…), your pedals have relay-based bypass.  Minimal contact voltages inside the relays.  Ok, so back to the MATH.  2 Jacks, 2 Plugs, 1 DPDT bypass connection (2 contacts), 10 pedals.  That’s 80 contacts using a mechanical stomp switch!

80!

What I am getting at here is that’s an awful lot of places where your signal can degrade.  80!  It really only takes one faulty, dirty or otherwise weak connection to wreak havoc on a passive guitar signal.  So lets do some more MATH.  Suppose a typical mechanical connection is 10 ohms of contact resistance.  10 ohms is tiny, minuscule.  No one even uses a 10 ohm resistor when building pedals because its basically a jumper.

Now dig, 80 mechanical connections X 10 ohms = 800 ohms!  800 ohms is basically 1K ohm, and that can be a big deal on a passive guitar signal.  And this is all assuming there are no problem children, err, dirty, broken, intermittent contacts.  And don’t even get me started if you’re using one of those fancy programmable switchers.  You should just give it another factor of 2-4x.

Now for the punchline.  Say you have a buffer.  Doesn’t really matter if its an Op-Amp or Discrete, you just have one.  A buffer is any preamp/active element that presents the guitar with an ideal input impedance (resistance) and provides a lower, more ideal output impedance for driving heavier loads.  Put that buffer after the guitar, (or some where in the middle of the pedals even).  The output of that buffer will have no problem handling an extra 1k ohm on its output.  Hell, it was designed to do this.

Here’s a nice, tidy example of an Op-Amp based buffer.  This is my Micro Buffer/Splitter design that I have been selling for almost two years as a pre-built mono buffer, or a DIY project.  Personally, I think this buffer sound best AFTER all drive and fuzz pedals, but before any modulation or time-based effects.  That’s just my opinion anyway, your ears may tell you otherwise.  It can be configured as a splitter, mono or stereo buffer depending on how you populate the jumpers (J1, J2, etc). Micro Buffer Schematic

There are many other interesting products out there such as the Cornish LD-2 which is a discrete, bootstrapped design, as well as the Visual Sound Pure Tone, which is another Op Amp buffer.  You can read an argument from Pete Cornish against True Bypass here, and another here from Andrew Barta of Tech 21 NYC.

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