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Boost and Overdrive

The Kuro Custom Audio P.h.A. Boost/Overdrive/PreAmp is a rare High Adaptability Gain Modifier and Tone Transformer

Blues Breaker Style OverdriveBoostBoost and OverdriveDriveKlone and Transparent OverdriveKuro Custom AudioMulti-DriveOverdriveTubescreamer Style Overdrive+-
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I must confess that when I first came across the Kuro P.h.A. I kind of rather dismissed it as yet another of those myriad just a tiny bit different overdrives. I think I was to a large degree misled by a number of the earlier fairly uninspiring and unrepresentative demos. I can’t overstate the importance of a good demo towards portraying a just and accurate account of a pedal’s range and capabilities. Mediocre and underwhelming demos can ever undermine and taint the reputations of even the most stellar of devices.


So it was only when Giulio shared the below new demo video with me that I finally got switched on to the finer qualities and true nature and range of the P.h.A. Overdrive. P.h.A. weirdly stands for Potentially Hazardous Asteroid - which reflects an astronomical event at the time of its development, but I would rather repurpose the acronym towards ’Prodigiously High Adaptability’ - as that moniker more ably represents the fundamental essence of this pedal.


The development story actually starts with Guilio’s dislike of any kind of compressed sounding overdrive - and in particular the sort of compression you get on the typical TS808 or TS9 style pedals. So the starting point was to create an elegant fully open and expansive overdrive with extensive abilities to adapt tone and gain structure towards any amp and playback scenario. To the point that this one single overdrive/preamp would be your automatic and first choice for a multi-tasking fly-rig.


Giulio set to working with a number of different soft-clipping OpAmps - to find The one which gave him the most balanced and elegant character right across the gain range. He was surprised in the end that the best candidate turned out to be a rather widely available very moderately priced OpAmp - which gave him exactly the qualities he was looking for. There is a second 18V charge pump OpAmp which gives the overdrive its High Headroom and extended fidelity, and to further extend the gain range of the pedal Giulio settled on twin Red LEDs as the perfect means to provide a near undetectable higher level gain sweep. The two Red LEDs come into play at around 11:30 - 12:00 o’clock and they’re so elegantly calibrated that it’s nigh impossible to detect their onset.


I’ve included an illustrated overlay in my above visual in order to portray the smooth sweep of the gain range - and unlike with several alternatives there aren’t any audible steps in the taper of the knobs - you just get the most fluid extended range - which goes from a wholly clean boost, through lower-gain overdrive, then breakup and crunch - and onto some considerable soaring saturation. I benchmarked the P.h.A. against a number of my favourite drives and distortions - including in roughly 12 Degrees of Saturation order - the ThorpyFX Peacekeeper, Jackson Audio Golden Boy, Keeley-modded Boss BD-2, Menatone TBIAC, Menatone KOB and finally the MI Effects Super Crunch Box V2 - my favourite EVH / Brown Sound / JCM800 style distortion. And the incredible thing is that the P.h.A. pushes my clean pedal-platform twin-amp rig to the same level of saturation as the Super Crunch Box! Obviously it’s texturally different to the hard-clippers, and there are some characteristic differences too understandably - but the P.h.A. can match those 6 pedals pretty much toe-to-toe across the range. It doesn’t have quite the chewy mids of the Plexi style, nor the overly saturated harmonics of the Blues Driver, or the exact same softness of the Peacekeeper as I have that set up - but it delivers its own exceptionally pleasing tonality right in the territory of how I like to have my favourite long-term pedals set up.


In fact the secret weapon of the P.h.A. is not really its charge pump or Red LEDs, but rather its dual-band Baxandall Active Hi and Lo controls. Those have a huge influence on the saturation and gain levels of the pedal as well as the core tonality - and when you want the higher gain levels you obviously move all the dials well into the right-hand hemisphere. What is really remarkable about this pedal is its even-handedness, perfect poise and balance, and ultimate utility right across the range of every dial. There are very few pedals with this high degree of gain and tone-shaping which still sound elegant and wholly usable at every extreme. The tone never gets overly harsh or weedy and thinned out - despite the fact that you have ±15dB of Boost/Cut on both Hi and Lo frequencies. You also don’t get hung up with micro-movements of the dials - as the taper on each of those knobs is perfectly calibrated and smooth and predictable - and always lands pretty much exactly where you want it to.


This is a genuinely rare and unusually elegant overdrive which has just the perfect balance of harmonics and breakup whichever level you aim for - it’s so finely balanced in fact that you quite marvel at its poise once you get your hands on it and start tweaking. The one thing to be aware of is how interactive all the dials are - and with that much range on tap - ramping up either Hi or Lo frequencies bumps up the gain and saturation and therefore volume too - so there is a degree of needing to tweak things in tandem. I believe the Active Baxandall controls are of a pretty similar type to those employed on the Kuro Akuma Fiery Fuzz - which is one of the key reasons I so liked that pedal. I’ve been such a staunch advocate for 3-band EQ, that I had kind of forgotten how appealing a powerful 2-band EQ could be - just lower both the Hi and Lo dials below their midway points to get a Mids boost for instance - but be aware that you will need to compensate a touch for the lower volume output and gain.


I believe the gain dial was set around 3-4 o’c to match my MI Effects Super Crunch Box, and both tone controls were at similar levels. There’s so much body to this pedal that you can afford to have the Lo frequencies knocked back a fair bit quite a lot of the time - while when you push them - you really get that extra level of body and saturation in the higher reaches of gain.


For me this pedal has gone in on slot #15 in place of the actually not long since arrived Menatone Vertical Fish Factory - which of course I still love too. I just feel that the P.h.A. gives me a little more of everything - certainly with its extra tone-shaping abilities and rather impressive gain range. I’ve yet to decide on which is my exact preferred use for this pedal - as I really like about half a dozen different settings at the moment - likely to be somewhere below mid-level gain. It’s a pedal that’s certainly worthy of your consideration, and I’ve had to be really careful in this article not to heap too many superlatives on it. In a sea of a million overdrives - this one really is special. It doesn’t exactly replace or oust my other favourites as they each have different characteristics and textures - but as an all-rounder overdrive it has to be easily my favourite of that type!

June Chain

Tech Specs

  • High-Headroom, High Adaptability, Fast Attack, Soft-Clipping 2-Stage OpAmp-driven Boost/Overdrive/PreAmp
  • 18V Charge Pump OpAmp for extended Headroom
  • 2nd Stage Dual Red LEDs for smooth and controlled extended gain range
  • Active Baxandall 2-band EQ with ±15dB of Boost/Cut for extended tone- and gain-shaping
  • Ranges from Clean Boost to JCM800-style levels of gain saturation
  • Suitable across the widest variety of clean and driven amps
  • Consistently Elegant and Controlled Breakup/Overdrive - never Harsh or Hollow sounding at any extremes of gain or tonality
  • Full-range Utility on All Dials - fully usable tones throughout each knob's control sweep
  • 19mA Current draw

Killer Full-Range Demo


Who is this pedal for?

In my opinion this is one of the truly great soft-clipping overdrives. For those that kind of like the tonality of Tube Screamers but not their compression - and want more from their overdrive (including more openness) - this should be your lead candidate. Also those truly eclectic and multi-genre players who need more range from their overdrive to cover and capture different styles of music - the P.h.A. is the perfect candidate for that too.


I would also like to nominate the P.h.A. as the perfect Fly-Rig Overdrive for jobbing and gigging musicians. If you're heading out to a session and are not sure what you might need or where you will end up - then you'd best pack a P.h.A. for that trip.


I've said before that it doesn't exactly match the softness of my preferred Peacekeeper settings or the super-saturated harmonics of the harder-clipping dual-stage Keeley-modded Boss Blues Driver - but it's right on target with the feel, tonality and saturation levels. I found the nature of the dial ranges far easier to tweak than say the many dials of my Boss OD-200 or MI Effects Super Crunch Box. I really can't get away from saying that there's something just a little bit special about the P.h.A.


I think it's very reasonably priced at €169 - and for someone who is usually a fan of lots of dials and switches I was very pleasantly surprised by how enormous a range I could cover with just those 4 beautifully calibrated dials. Giulio likes to say that there is no magic fairy dust here and no magic ingredient component - yet the way the circuit has been calibrated and tuned seems to lead to some special magic of its own.


For some this will be their favourite all-time overdrive, for others one of their very favourite all-time selections - no other rationale seems conceivable here! Get yours now from the Kuro Custom Audio Store before everyone else realises what they're missing out on - you need to email Giulio via These are of course hand-made boutique pedals - beautifully assembled and finished with the highest attention to detail inside and out - per the above visual.

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Stefan Karlsson
Stefan Karlsson
Guitar Pedal X
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