August 5th, 2012, 01:00 PM
Not going to do a huge review, because it sound pretty much exactly like the King of Tone... just single-channel and single-sized (Fulltone, ARE YOU PAYING ATTENTION?!?!?)
Anyway, it's got the same KOT signature high-mids spike. It does have an internal dip switch to add more low-mids, and I'm sure it's doing something, but it's very subtle. The internal compression dip switch, on the other hand, is very noticeable.
These come with a 4580D.... and the KOT/POT is know to drop a little bass (some like it, say it "tightens the bass", and "keeps you from getting to muddy in a band")... anyway... I tired a 4558D in it, and there is a subtle difference... but before I believe my own ears (or should I say, "before I believe what I WANT to believe"), I thought I'd ask: all other things being equal, what are the tonal differences in these 2 chips? Is there a significant gain difference? Does one perhaps maintain bass response better? etc?
I will say, with the 4558D, the POT sounds a bit more like many other ODs out there, the stock 4580D definitely gives it a less generic tone. (altho still pretty generic, as ODs go... only so many ways you can make an OD).
August 5th, 2012, 01:48 PM
I love the boost mode w/the gain cranked with P90's and Humbuckers.
August 5th, 2012, 04:48 PM
You might also try a TLO72 like the original Blues Breaker used.
August 6th, 2012, 06:02 AM
I tried different chips with wilson grasshopper and do not notice a big differences between chips. I am actually do not remember all, that I tried, some JRC and TL.
August 7th, 2012, 10:12 AM
...all other things being equal, what are the tonal differences in these 2 chips?...
...the stock 4580D definitely gives it a less generic tone...
It's not a big difference. The 4580 is the "new cheap audio standard op amp" for many applications. Translation - it's used in a TON of stuff, and is basically the "4558 for the 21st century." It's in the Bad Monkey, and you will probably find it in computer sound cards, home stereos, etc. Super cheap, and has an "improved gain bandwidth product." Whoopty doo.
The TL072 in the original Marshall pedals is a "jFET input" op amp, and actually is slightly different sounding - you get a touch more of that "glassy attack" sort of thing, and it can make to clipping just a touch more gritty. If you consider that John Mayer used an early V1 BB for some of his stuff and folks ooh and ahh over that, THAT is the advantage of using the original op amp chip. That said, the diodes in the original BB V1 will give more of an audible difference vs. what Mike stick in his. I think the idea with the K/PoT was to make the BB V1 core attributes a little softer/blurrier sounding, especially when you consider that there is the dipswitch to pull the diodes, and the trimpot to reduce the effectiveness of the tone control (or "treble boost," as it is called).
...IOW, the things that guys like Mayer and early V1 BB owners love about the stock Marshall pedal are things that Mike has cited as being problems with it, which is why he had his buddy in Japan do all the chip and diode swapping, why the trimpot was added, and why two were put in a single box for the KoT.
So I would argue that you could swap chips all day and hear minor differences, but the big difference would come from swapping the diodes. Since they are hardwired and you can only turn them off with the dipswitch, it makes it hard for someone to hear any differences vs. other diodes. And it is still just an experimentation/taste/judgement call kind of thing.
IMO, it is a rare few pedals like the Zendrive where the op amp chip itself has a pretty noticeable affect as far as folks preferring one chip over another. And even then, a percentage of users will still have no preference. Another pedal where you can hear a big difference is the Crowther Hotcake, because it has no clipping diodes in the design. Early HC's had the old LM741 and were more "greasy/saggy/growly" sounding, but Paul went to the TL071 (with jFET inputs like the TL072 in the Marshall pedals), and it has a glassier/clearer/"gritty blackface Fender" sort of quality to it.
...Just FYI, "jFET input" essentially means that the op amp circuitry has a considerably higher input impedance, which is why the chip has the potential to be brighter/grittier/"more sparkly" than the JRC45XX series, which have "standard bipolar input" transistors, which give the softer/furrier kind of quality that is popular with the TS/SD-1/etc. There is also the LM833 which is VERY similar, and has found its way into other Marshall pedal variants like the Crunchbox. The Suhr Riot is also a V1 Guv'nor variant with the 4580 chip. With more pedals like the Bad Monkey and Riot being SMT, the 4580 is basically seen as the 21st century standard. It is possibly the most common SMT audio op amp available.
Again though - none of these chips are chosen for "superior performance" - they are all chosen based on cost, and none carry a "premium" price tag. You only see the "home stereo chips" being pushed with some of the mod kits that are for sale, with the principle of a distortion pedal that creates no distortion somehow being a good idea. IMO, it makes as much sense as the first solid state guitar amps did, and you know how well that went over!
August 7th, 2012, 05:03 PM
Thanks Keith. I didn't hear much difference at all between the 4580 and the 4588. MAYBE a subtle difference, but then I could be fooling myself.
The KOT/POT drops a little bass by design, and has a high mids spike, reminds me of the DOD250 believe it or not, for some reason. I tend to prefer drives that do not drop any bass, and have a low-mids bump, if any. It's probably just that the KOT/POT isn't my bag (or at least not with this rig), which would explain why I sold my KOT the first time around.
August 13th, 2012, 06:20 PM
Well, I've decided to keep the POT... but not as an overdrive. I much prefer my FD2 and Paisley Drive for that. But the EQ signature this thing has is perfect for 80's metal in distortion mode! The way it drops a little bass, rounds off highs, and boosts high mids, it's perfect for that tone. It's my "Yngwie" pedal!!! Not sure Mike would be happy to hear that... lol