Archive | Cold Hard Facts

Big Muff Tone Control Alternative

I haven’t posted much in a while, mostly because I have been very busy building pedals and introducing new products.  So here’s a little snippet I’ve been working with for a while.  The Electro Harmonix Big Muff Pi uses a very simple tone control to mix between a high pass and a low pass filter.   This arrangement of filters lets you get a wide range of EQ curves from flat to scooped depending on the values use, and allows the pot to function as a tilt control.  It cuts bass as it adds treble and vice versa.

This style of control has been used on lots of other effects as well, such as the Boss DS-1 for example.  While toying with it, I realized that in some circuits, I prefer the bass response of the tone at Noon and would rather have it not cut bass when adding treble.  By adding 1 resistor and shorting pins 1 and 2 of the pot you can do just this.

Big Muff Alt

In the alternative configuration, R4 controls the fixed mix of the low pass path.  A good starting point would be to make R4 half of the original tone pot value.  Reducing the value of the tone pot will increase the amount of treble in the lowest setting, but leave the maximum fixed (when pin 2 is shorted to pin 3).  R4 could be made a trimpot internally to tweak the bass mix as well.


Boutique vs Premium


I have to say, I hate the “boutique” name used for music gear.  In today’s market, if you’re not mass-produced, then you must be boutique.  Boutique has come to include everyone from the most fantastic, start up designers putting out quality gear at competitive prices to the overpriced, under-constructed klones that flood the market.  It’s so unfortunate that most of the latter are so poorly constructed, they simply aren’t worth the the asking price.  They’re not built to last, they’re not built and marketed with integrity and that’s a shame.

Be wary.  Hand-wired does not not always mean Cornish quality.  More often than you would like, hand-wired means fragile.  This is not to say these “boutique” pedals don’t sound great.  Some of them certainly do, but is it really worth your money if its so fragile?

How it should be done.

Now I’m not going to name any names here.  I’ll leave that to the independent bloggers and reviewers to shed light on, and I think they should.  Musician’s should know what their hard-earned money is going towards, especially if its not worth what they are paying.

Alternately, I suggest we carve a new class of pedals out of all this.  One worthy of buyer’s confidence, built to last with integrity and uniquely designed, not just uniquely marketed.  For lack of a better term, I propose we make the distinction between the Boutique and the Premium, because here’s the thing.  If you building products with integrity, you aren’t afraid to show the insides to back up your claims about wiring, and construction.  You’ll take the time to explain and demonstrate how bulletproof your manufacturing process is, and you’ll back that shit up with a worthy warranty.

Of the current manufacturers, I see at least the following as the Premium class of effects , and worthy of your hard earned money.  I’ll to update this list as I discover others.

  • Caroline Guitar Company
  • VFE Pedals
  • Mr. Black Pedals
  • Dr. Scientist
  • Subdecay Studios
  • Catalinbread
  • Earthquaker Devices
  • Strymon
  • Neunaber Technology
  • MI Effects
  • Blackout Effectors
  • Spaceman
  • Eventide
  • Empress


Batteries = Yuck

9v-batteryYou’ve heard this before.  If you want the cleanest power possible, batteries are the way to go.  They are isolated, clean DC power, but they’re also bad for the environment.  Anything that is thrown away is just a bad idea.  For all effects pedals, I recommend using some sort of multi-power DC supply.  Recently, Mr. Black Pedals has taken a stance on different types of DC supplies, and I think its a great argument.

All I want to say here is that batteries are just a bad idea for more than one reason, and that’s why I don’t bother putting room for them in our pedals.  Batteries are,

  • Bad for the Environment
  • More Expensive in the long run
  • Less Reliable & Easily Drained if Left Connected
  • Always in a state of Partially Drained
  • Gig-Nightmares
  • So, so uncool.

And so, instead of leaving room for a dying power source (get it? dying…battery!) in our products, we’ve left that space open for adding features in the future as the part of the Soft-Touch Bypass board that is in every effect we make.  Future products will have effects loops, expression controls and remote I/O.


Noisy Compressors & Downward Expansion

Compressors have been around a long time and they can do some wonderful things.  You can gently limit spikey peaks, or even out your overall dynamics, or you can squash the hell out of your signal for some really funky, punchy stabs and single lines.  Compression is a great tool.  But its also a noisy bitch.

All that squashing and pumping gets applied to the noise as well.  Compressors work by lowering the volume on loud passages and raising it on quiet ones.  When you stop playing, all the background noise of your guitar and previous pedals is amplified way more than it should be.

So what’s the solution?

A compressor with in-built noise gate.  The as-of-yet unnamed compressor from Coldcraft Effects actually has two thresholds for dynamics control.  One for Compression and one for Downward Expansion.

Downward Dog-errr WHat?

Downward Expansion is a process where all signals below a set threshold are reduced in gain.  This means there is a minimum level at which the guitar signal is let through with full force, and below that, all signals and noise are made progressively quieter and quieter.  Genius?  No.  Really f*ckin’ Awesome?  Yes.  Yes indeed.

Compression Preamp


Audio Myths & Marketing Tricks: Burn In

The topic of “Burn In” concerning guitar and hi-fi audio equipment has been discussed over and over again.  Unfortunately, its still as cloudy as a good Hefeweizen when it comes to actually making sense.

Many manufacturers and even dealers will give you a “burn-in” claim on a bunch of different components or products, that they require X amount of hours of being on, or running signal before they start to sound good.  For most components this is complete rubbish.  Capacitors polarize within seconds of applying voltage.  Beyond that, I dare them to explain what will change in an opamp, cable or PCB as the result of applied voltage and signal.  Rubbish.

Isn’t it ironic that the quoted “Burn In” time is just long enough for you to forget how it sounded in the first place?

There are two places where burn in has some truth.  Speakers & New Tubes.  Obviously Speakers are mechanical and thus can have some settling after use, but I am not an expert on speakers so I will refer you to an article.  As for newly installed tubes, it can take minutes or hours for the bias to settle for the first time.  I don’t pretend to be an expert on this either.  None of this applies to solid state devices, and especially not passive components.

So where did this hogwash come from anyway?

The one thing that can happen is “Burn Out”.  Components can fail over time.  OpAmps, transistors, you name it.  The myth surrounding “Burn In” of these devices is most likely taken from the factory specs.  Traditionally, most devices will either fail right away, or towards the end of their specified life of operation.  Back when quality control was more difficult, components would be tested at the factory for a short time to insure that the “duds” were removed before they went out into the world.

So the next time that high end upgrade, recap or premium cable comes with a burn in clause, be wary and ask yourself one question,

Why didn’t they burn the damn thing in at the factory?


Pickup Wiring “Tap Link”

Another wiring mod I’ve stumbled across is called a “Tap Link” and works for guitars with dual humbuckers.  Basically, you can link the mid-point of the two humbuckers together, so that when you activate just the neck (or bridge), there is 1 coil from the unselected pickup wired in parallel.

I find it easier to understand if we say that 2 humbuckers = 4 coils.  Using the “tap link” activates 3 of the 4 coils.

I’ve taken the previously shared “4way 3 knob Tele” wiring for 2 humbuckers and changed 1 connection to achieve a slightly different set of options that includes a tap link setting.  Can you find the change?

4way Tele Tap Link

If you guess the L2 (Bridge) to Pin 5 connection of the switch, you are correct!  The lower end of L2 now connects to the upper end of L1, which means, that the bridge is always active, always in series humbucking mode.  In position 2, the switch actual shorts L2, instead of leaving it dangling.

I also dropped the bass control, just for simplicity.  I left the “Sweet Switch” in, which is the additional treble roll off using C4 in the Bridge Setting only.

So the single change from the previous diagram affects the function of positions 3 and 4.  3 was previously 1 single coil from each humbucker (neck and bridge), in parallel, a traditional tele setting.  It is now both humbuckers in parallel.

Position 4 was 1 single coil from the bridge in SERIES with 1 from the neck, the usual 4way Tele mod.  A very nice, punchy humbucking tone.  After the change, the 4th position is now the full bridge humbucker, with 1 coil from the neck in parallel with the upper bridge pickup.  Kind of a series/parallel combo.  It should be somewhat hum canceling, but not entirely.  It would sound like the bridge humbucker, with a little bit of single coil neck mixed in.

It would be simple enough to use a push-pull volume pot to combine this new mod with the original 4way dual humbucker scheme to get the best of both.  I wonder how this would sound using some kind of split-coil humbucker where each coil only covers 3 strings?


4-Way ‘bucker Tele Wiring with Sweet Switch

I came up with an interesting mod to the 4-way Tele wiring I posted previously.  I’m really a big fan of the 4-way switch option.  Maybe 4 is my magic number and 5 is just to complicated for me, I don’t know.

Anyway, what I’ve done here is take the Custom 4-Way wiring and add a Master Bass Roll Off, similar to what I put in the 4-way Strat wiring.  This type of bass control comes from the G&L Legacy.  I would recommend using dual stacked pots.  Unfortunately, I don’t think you’re going to find a 250k/1MC pot, but you can definitely find dual 250k as well as 250k/500k.  I haven’t evaluated how awkward or inconvenient it might be to stack the tone with the volume, leaving the bass by itself, but it’s here for your information.  You can always drop the bass control by shorting out its connections.

As shown, the wiring is humbucking in all positions,

  • Full Bridge Humbucker
  • Half Bridge/Half Neck in Parallel
  • Full Neck Humbucker with extra bass roll off (C3)
  • Half Bridge/Half Neck in Series

The 2nd thing I’ve done is to replace the bridge-activated tone control with a fixed “sweet spot” tone roll off that is paired with a traditional tone control.  What this does is allow for some extra roll off when using the bridge position, but also let the master tone do its thang.  C4 is the fixed “sweet” cap and will usually be a smaller value than C1.   You’ll have to experiment for find the right setting for you.  R2 should be 1M Ω.


I’ve also left on the 500kA Volume pot.  This will brighten the guitar in all positions, giving the tone switch and control more signal on which to work the magic.  Last but not least, I’ve added 2 coils to the setup, representing the additional options when using humbucking pickups in the neck and bridge.  Shorting L2 and L4 will return the diagram to the 4-way single coil wiring.


Buffers and what they’re really doing.

There’s a lot of information around the internet on buffers, their use and placement.  The following is my professional opinion on buffers as they apply to guitar signal.  Just a warning to the reader, I am going to be using the term “Impedance” quite a lot.  Impedance is just the technical term for the measure of the opposition that a circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current (AC) circuit.  I took that last bit from  You can think of impedance as the resistance of a circuit to an AC signal.

While buffers really can’t hurt your signal, there is such thing as over use or “less than optimal use”.  Buffers come in many different varieties such as discrete transistor, JFET, MOSFET or OpAmp types.  Different types of buffers have different ideal uses, but all perform the following 2 duties,

  1. Present the Guitar (or input signal) with a fixed input impedance.
  2. Provide the signal with a fixed output impedance.

JHS Prestige, one of many
MOSFET-based Buffer
& Sparkle Boosts

A few things to note.  You may have noticed that I did not write “high” input impedance.  Some buffers are designed to give the guitar a very, very high input impedance, much higher than that of an amplifier.  This has the effect of adding “Sparkle” to the guitar signal.  The thing to understand is that, when you plug your guitar straight into an amplifier, some high frequencies are being rolled off.  This is just how a passive guitar (read: not low output impedance) is affected by the input impedance “seen” at the amp input.  By using a buffer with a very high input impedance, you are giving the guitar a much stiffer load, and so the highest treble frequencies that were previously rolled off at the amp are preserved at by the buffer.

This is the function of many “sparkle boosts” such as the Zvex Super Hard-On, JHS Prestige & discontinued Mr. Magic Boosts.  “Sparkle Boosts” are usually designed around a discrete MOSFET transistor for its very high input impedance.  Actual input impedance is fixed by resistors to be anywhere from 2.2MΩ to 10MΩ.  A typical tube amp has an input impedance of 1MΩ.

Just a note for comparison, standard JFET stages are usually designed for an input impedance of 1MΩ, whereas simple Bipolar Transistors (read: regular transistors) would have slightly lower input impedance, 100kΩ to 500kΩ.  The quick and dirty explanation for this is that traditional transistors are current-controlled devices and need to draw more current from either the signal source (guitar) or the bias network, resulting in smaller biasing resistors and a lower input impedance.  JFET/MOSFET transistors on the other hand are voltage-controlled devices and draw very little current from their inputs.  For a concise but informative look at different buffer styles, I invite you to have a read over at the AMZ/ writeup by Jack Orman.

On to the 2nd point.  I also stated “fixed output impedance” and not necessarily low output impedance.  Lower is not always better when it comes to interacting with other impedance.  Some fuzz and dirty pedals really want to see the guitar directly, and thus will work best when connected to a medium output impedance, but will seem less dynamic driven by a low impedance, and just fart out completely if driven by a high impedance.   You may have noticed that the run-of-the-mill Dunlop Crybaby Wah will stop its waka-waka magic when driving a vintage style Fuzz Face or similar.  This is because the output of the Wah is unbuffered and on the high side, and the input to the Fuzz is on the low side.  When combined, the fuzz actually loads the wah enough to change its operation, and that’ just a shame.

The FoxRox Electronics Fuzz Wah Retrofit,
a perfect example of an Isolation Buffer.

So what is the fix?  Add a buffer to the output of the Wah so that it always sees a fixed load.  But if said buffer has too low of an output impedance, the fuzz loses its dynamics.  The solution?  Raise the output impedance a bit.  This may seem counter intuitive, because before adding the buffer, the Wah had a high output impedance but this brings us to the actual function of a buffer:

  • A buffer provides impedance isolation between source signal and load

You can see a wonderful example of this isolation buffer in the Foxrox Electronics Wah-Retrofit, a buffer module designed to drop in at the output of a wah, letting it play nice with vintage style fuzzes.  The output impedance of this circuit is higher than your typical/traditional opamp buffer.

This brings up a quick point I’d like to make.  Manufacturers will sometimes tout their design as JFET or BiFET preamp when in actuality it is an OpAmp.  Technically this is correct because OpAmps are in fact made of many internal transistors, including combinations of JFET and Bipolar Transistor (BiFET).  There are even MOSFET-based OpAmps.  This is just something to keep in mind.  Usually the honest manufacturers will only say “Discrete” when it is actually individual transistors, JFETs or MOSFETs.

So it seems like isolation is a pretty good thing to have when you have multiple effects pedals chained together.  What other places will isolation buffers benefit the performance of your gear?  Take this next example.  Some designers are lazy, and don’t put output buffers last in their circuit.  This could mean that the output impedance is not constant and can actually change with the volume control (usually the last control in the signal path).  Sometimes this can affect their performance with other effects down the line.

The MXR Carbon Copy, often blamed
for the poor design of the Fulltone OCD.

A PERFECT example of this poor design is the Fulltone OCD Overdrive paired with an MXR M169 Carbon Copy Analog Delay.  Marketing hype aside, the OCD has one very big flaw that has never been addressed in its 7 (8?) revisions: the Output Impedance is too high and varies with the volume setting.  Many users have complained that the tone of their OCD changes when they activate their Carbon Copy after it.  This is because the Carbon Copy may not have an input impedance replicating that of an Amp, but also because the output impedance of the OCD can reach as high as a few hundred Ω’s.  Not cool.

Now dig, simply by placing a traditional buffer between the two (1MΩ Input/1KΩ Output) you can eliminate this problem.  What this buffer does is isolate the drive pedals from the modulation/time-based effects.  All drive pedals will see a constan 1MΩ load and all time based effects will see a constant 1kΩ signal source.

This is where I usually encourage users to try out the Coldcraft Micro Buffer, as its specifications were designed specifically for this sort of isolation application.  You can think of this buffer as a sort of “repeater”, taking everything from the dirt pedals and resetting it back to low output impedance, usually mid-pedalboard.

Lastly, buffers can be used to drive isolation transformers.  Often, guitarists will use multiple amps, sometimes driving them with stereo signals.  This can make for some really sweet, thick and rich guitar tones, however it can add many noise headaches by creating a ground loop.  Say you have 2 amps, plug them into the same output, and use the stereo out from your Strymon Timeline to drive them both.  The cables running from the pedal board to the amp are grounded both at the pedal board and the amp.  This creates a ground loop that may or may not add a nasty hum to your rig.  This depends on many things including the quality of power where you are playing, and often times the power at the bar is very noisy.

Suhr Iso-Buffer

Now you could disconnect one of the amps from ground, but this can be very dangerous for the player, even fatal.  So don’t do that.

What you can do is use a stereo buffer/splitter at the end of the pedal board to drive one amp directly, and the other through an isolation transformer.  The transformer eliminates the ground at the pedal board end while leaving the signal grounded at the amp.  Perfect, not only do you have a low output impedance taking care of really long cable runs, keeping your signal low noise, but you’ve eliminated the possibility for nasty ground hum.  This is the basis for the Iso-Buffer by Suhr as well as the Humdinger by theGigRig, among others.  Neither example takes a stereo input unfortunately.

So to summarize, I believe the 4 most important applications and types of buffers are the following,

  • Input Buffer – Personal Preference, Post-Guitar
  • “Wah Buffer” – Slightly higher than low output impedance
  • “Repeater”  – OpAmp to Isolate dirt from mod/time effects
  • “Output Isolation” – Transformer Isolated for driving multiple Amps

And this post would be complete without putting my money where my mouth is so here is exactly what I would do if building the ideal buffer system according to me.  I’ve selected a hybrid input buffer that uses a bootstrapped transistor for low noise and RFI rejection, coupled to a op-amp that provides a little filtering and plenty of drive power.  The signal splits, providing an isolated tuner out, and a main output with a tunable output impedance.  I would recommend this if you’re into the fuzzies that have low input impedance.  Next is a quick and dirty wah-output buffer, again with the tunable output impedance for best performance. This gets tacked onto the output of the wah, and is only active with the wah.

Ultimate Buffer System

The third section outlines the mid-pedalboard “repeater” design, not all that unlike the Micro Buffer sold through this website.  Lastly, the OpAmp has been used yet again to provide transformer isolation driven from either a Mono TS, 2x Stereo TS or Stereo TRS signal send to 2 amplifiers.  For pedal board wiring purposes all this would be in separate boxes.  I usually recommend TL072cn OpAmps for buffers, which are JFET-input.   Ignore the LM4558N, that’s a typo.  The 42TL018 is a standard isolation transformer sold by Mouser and Small Bear Electronics. There are probably many others that will provide similar or better performance.  Dig.


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?


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!


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.


4-Way Hum-Free Strat Wiring

After the post on my 4-way Tele wiring scheme, someone asked how I would prefer to wire up a 3-pickup strat.  Not really being a strat-guy I tried to come up with something unorthodox using the same 4-way switch as my Tele wiring.  Traditional Fender wiring for the Strat gives the following options,

  1. Bridge (No Tone)
  2. Bridge/Middle (Tone 1)
  3. Middle (Tone 1)
  4. Middle/Neck (Tone 1+2)
  5. Neck (Tone 2)

Now, my 2nd guitar growing up was a Strat-style, so I am quite familiar with the ice pick bridge that comes from the lack of tone control.  I’m also not a big fan of hum, so after spending some time brainstorming, I came up with the following 4-way wiring scheme for a 3 single-coil Strat.

4way Strat Wiring

I’ve opted for a Master Tone control, and a Master Bass control, as used by Leo Fender when he designed the G&L Legacy.  The Legacy was Leo’s final say on the Strat-style guitar.  You may also notice that this wiring includes an extra cap to ground (C3).  I have not tried out this wiring yet, but it would seem to me that it would be quite smooth, without the ice-pick that annoyed me so much.  The bass control would definitely keep the guitar from sounding muddy.

On to the pickup combinations.  What I’ve done here is only used 2-pickup combinations, either in series or parallel, and always with the bridge pickup.  The combination of the bridge with either the neck or middle should work to balance out the highs and lows for a full sound.  In my experience with the Tele parallel/series, I would expect the series settings to be slightly louder and warmer, whereas the parallel combinations would be brighter and punchier.

One last caveat.  To achieve true, hum-cancelling operation, you must use/wire reverse wound, reverse polarity Middle/Neck pickups relative to the Bridge pickup.  You may see this used on a parts-caster in the near future.  Actually, its the refinished body of the Strat I mentioned.


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