Earthquaker Devices - Arrows  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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bc108
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Post by bc108 »

Anyone?


Another modified Electra?

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palomaeki
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Post by palomaeki »

_20190224_024026.JPG
_20190224_024048.JPG
Here's some shots kindly provided by PGS. I'm also interested in this since I was asked to if I could build something like it for a friend. Surprisingly nobody seems to have traced this?

Nothing too complicated - haven't compared it to the Black Eye etc. yet but it must be a revision of something familiar? AMZ Booster maybe?

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Bononoob
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Post by Bononoob »

So a buddy lent me a EQD Arrows so I traced it
Here's the Eagle Schematic and some gutshots
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IMG_20190511_160430.jpg
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EQD Arrows Schem.png
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storyboardist
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Post by storyboardist »

You're really close. I traced this about a year ago, and the value off the resistor off the emitter in your schem is way too high. Should be 1.3k. And the 100k at the output goes to ground. If anyone needs a PCB I still have a few. Schem attached.

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storyboardist
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Post by storyboardist »

Aw heck, here's vero, perf, and etch layouts too.
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Arrows vero.png
EQD Arrows.png

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Bononoob
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Post by Bononoob »

Damn how did I mess this up
Anyway thank you for the corrections and boards that's awesome
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FeVeR2112
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Post by FeVeR2112 »

What does the R2 100R resistor do here? Seems unnecessary.

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Post by guiddruid »

FeVeR2112 wrote:What does the R2 100R resistor do
Limit current through D1 to ~90mA when the power is connected backwards.

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Post by FeVeR2112 »

guiddruid wrote:
FeVeR2112 wrote:What does the R2 100R resistor do
Limit current through D1 to ~90mA when the power is connected backwards.
Would you not just use the diode for polarity protection? A 4001 diode (1A) can handle pedal supply which are mostly 500mA at best.

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Nocentelli
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Post by Nocentelli »

I always understood that a ~100 ohm resistor + large electro capacitor together form a filter for the power that reduces hum.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by guiddruid »

FeVeR2112 wrote:Would you not just use the diode for polarity protection? A 4001 diode (1A) can handle pedal supply which are mostly 500mA at best.
Without the resistor, you're relying on the power supply to gracefully limit itself - not pop a fuse, burn out a voltage regulator, or blow D1. Best practice is to assume worst case conditions, which for this protection circuit would be a very low output impedance for the PSU.
Nocentelli wrote:I always understood that a ~100 ohm resistor + large electro capacitor together form a filter for the power that reduces hum.
C4 would need to be moved to be in parallel with D1 for R2 to help with filtering noise. That would also protect C4 - the only polarised component in the design (other than the diode) - from reverse voltage.

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Post by warsavius »

I recently did on the perfboard this nice pedal, it's for a friend, who asked for a mod on frequency boost. So I put a switch on c2 to choose from 4.7n 47n and 100n, a common mod in rangemaster.
But with this layout nothing happen, no sound change. Just the original (very nice indeed) sound.
How can I explain this? :scratch:

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Post by soulsonic »

warsavius wrote: 12 Dec 2020, 17:30 I recently did on the perfboard this nice pedal, it's for a friend, who asked for a mod on frequency boost. So I put a switch on c2 to choose from 4.7n 47n and 100n, a common mod in rangemaster.
But with this layout nothing happen, no sound change. Just the original (very nice indeed) sound.
How can I explain this? :scratch:
Input impedance is too high to give treble booster sounds with those C2 values. You'd have to go considerably smaller than 4,7n to get a significant bass cut. And there's already so much low end from 47n, that 100n wouldn't make any difference you'd hear.
Try: 500pf, 1nF, 2.2nF... small values like this for a treble booster sound. 10nF or 22nF would probably be more than enough for full range sound.
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CheapPedalCollector
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Post by CheapPedalCollector »

Pretty lame they charge so much for a pedal with $5 worth of parts in it.

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Post by Intripped »

Yes, it's true , but it's also true that in terms of factory costs of the finished pedal it doesn't make a big difference if the PCB has 10 or 30 components

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Post by warsavius »

soulsonic wrote: 13 Dec 2020, 01:01
warsavius wrote: 12 Dec 2020, 17:30 I recently did on the perfboard this nice pedal, it's for a friend, who asked for a mod on frequency boost. So I put a switch on c2 to choose from 4.7n 47n and 100n, a common mod in rangemaster.
But with this layout nothing happen, no sound change. Just the original (very nice indeed) sound.
How can I explain this? :scratch:
Input impedance is too high to give treble booster sounds with those C2 values. You'd have to go considerably smaller than 4,7n to get a significant bass cut. And there's already so much low end from 47n, that 100n wouldn't make any difference you'd hear.
Try: 500pf, 1nF, 2.2nF... small values like this for a treble booster sound. 10nF or 22nF would probably be more than enough for full range sound.
Ok, it's fine with switchable 4,7n and 1n input cap. Not too harsh like a Rangemaster, fully useful and reliable for single coils or humbucker with smaller cap. Thanks for the suggestion. :cheers [smilie=rlp_smilie_242.gif]

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Post by -X- »

Looks like a Zvex SHO derivative :hmmm:

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Post by roseblood11 »

-X- wrote: 02 Jul 2022, 19:49 Looks like a Zvex SHO derivative :hmmm:
Or a “derivate“ of one million other simple gain stages. SHO uses a mosfet...

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Post by Ben N »

-X- wrote: 02 Jul 2022, 19:49 Looks like a Zvex SHO derivative :hmmm:
Ummmm, no, not at all. It's a simple BJT NPN single stage boost - kind of similar to an LPB-1 or Gus Smalley's NPN Boost, with a tiny, subtle bit of tone shaping. There's nothing terribly clever about it, but it's a useful gadget for a variety of purposes. I build one and like it, but I'm not using it for the moment because my home amp has a solid state preamp, and I like this much better in front of a tube preamp. But I'm sure it will come in handy at some point.

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Post by soulsonic »

I apologize for the off-topic post, but: Maybe we shouldn't be categorizing EQD as "boutique" anymore? Mass produced things you can find at any big chain store doesn't seem "boutique" to me. Same can be said for several other brands that were considered boutique in the past. Wampler comes to mind...
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

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