Archive for May, 2014

Ibanez SS20 Session Man II

Saturday, May 31st, 2014

SS20

What is it?
Ibanez SS20 Session Man II Distortion/Delay multi-effect from Power series. Made in japan in mid 80’s.

Ok. Apparently the first session man wasn’t a flop enough. Sharing parts of the design with the first Session Man “multi-effect”, this unit pairs a nasty, short delay to what appears to be the same distortion section as in SS10. Board designs are completely different, as delay and chorus do not necessarily walk with the same footprint with each other. It must have taken a lot of work to create this. As features go, this one has your standard distortion controls, Level, Tone and Distortion. In addition, there is delay time control and series/parallel switch for the delay. Sticker on the left hand side of the battery lid tells us there’s more. Under the battery lid, there are holes, so that two trimmers can be accessed with a screwdriver. Those controls are a nice addition. Left trimmer controls feedback, or amount of repeats and the right one controls the overall mix of the delay.

SS20-guts1

Board design is on par with all the other Power series boxes. Same semi-dull traces as with most of them. But as always with effects that are feature packed, this one has quite a few components in there. The design has a lot of tweakability to offer. And all the features do look very interesting on paper. Distortion and delay in the same enclosure with reasonable amount of control over the features? I think at least firm is making notable amounts of money with similar features today..

SS20-guts2

I have no idea about the number of units manufactured, but i suspect the number is rather low. These don’t seem to move much on auction sites and the prices are, well. Low. It is a full analog device and while the features seem promising…

How does it sound?
Good? Not so much. The distortion part is pretty much 1:1 with the open, uncompressed distortion that the SS10 Session Man offers. So turn the delay level down to nothing and you have a reasonable distortion. Do whatever you want to the delay section and you’ll probably still want to turn it all the way down. Delay is simply set for way too short delay times, making this a reasonable contender for DOD Hard Rock Distortion. But not much more. Nice novelty effect, but i think it sounds a bit more useless when compared to SS10. If you want one, make sure you don’t pay too much for it. As that would possibly make you feel bad.

Boss HM-2 Heavy Metal

Wednesday, May 28th, 2014

Boss-HM2-HeavyMetal

What is it?
Boss HM-2 Heavy Metal distortion. Made in taiwan, early 1988. It has six number serial with leading zero, so that makes the unit one of the very first taiwan made HM-2s

If you have not heard anything about this distortion, you must have been living under a rock. It is one of the most desired Boss pedals ever, mainly due to swedish death metal frenzy back in the 90’s. The classic Daniel Ekeroth youtube video clip tells you everything you need to know about it. Due to it being in production from 1983 to 1991, the numbers are limited. There’s still plenty of them around, but since many death metal players try to get their hands on every single unit that they come across, the collectibility of these units is high. And the fact remains, it is the only pedal out there that gives you the authentic swedish death metal sound. Daniel is right about Metal Zone having nothing on this. They are very different designs. According to Effectsfreak, these should usually sell for less than $100, but i’ve seen units in good condition sell for a lot more. Well. It’s been over 20 years since Boss stopped making these, so some of the units must be dead and gone, others in use and some of them are in the hands of collectors. I smell prices rising r in the future.

Boss-HM2-HeavyMetal-guts1

Board is looking very appealing for a Boss design. Acidy styled strips with a crowded board always induce goose pumps. Apparently the board design has remained exactly the same when manufacturing moved from japan to taiwan.  If we take a look at the schematic (courtesy of hobby-hour.com), we see the distortion section after the input buffering/switching network to be quite unusual. Notice how the distortion control is wired – on the CCW end of the sweep it has maximum resistance between inverting input of the asymmetric clipping amp and ground (a similar method we’ll find on OD250/Dist+ gain control). While it’s doing that, it also tames the NPN/PNP transistor network that acts a pregain circuit. Once turned CW, the pregain has more effect – while the clipping amp is pushed to it’s potential. Ingeniously simple. After the asymmetric clipping amp we have two clipper pairs before there’s a buffer. After that buffer is the section which makes this a HM-2.

Boss-HM2-HeavyMetal-guts2

I bet the designer thought that simple clipping amp and the clippers after it weren’t enough for a design they were about to call Heavy Metal. Overall sound is fairly deformed at this point. The key ingredient is here – the three band active, Q boosting gyrator filters that offer up a big amount of boost for their selected frequencies. Low band is there to give out crushing lows and the upper two are controlled by Color Mix High control. This boosts mids and highs.

After that there’s a recovery stage, followed by standard level control and output switching/buffering. Rather complicated design, but successful in more ways than one. The gyrators mimicking EQ boosts are a thing of their own, but the pregain stage described above looks even more interesting.

On the negative side? Noticed the 330R resistor and D1 diode on the schem? Yup. This unit is meant to be used with idiotic Boss ACA power supply. Diode and resistor drop the unregulated 12V DC from ACA supplies to ~9V-ish. This unit cannot be used with standard regulated 9V supply. Or it can, but then you’ll need to daisy chain it with other pedals to counteract the effect of those components. If you are to try one with modern, standard pedal power supply, you’ll find the LED to light up dim and the sound being quiet octave up distortion. I know many people who have thought their units are broken due to this feature…

How does it sound?
Like swedish death metal from the 90’s. It is definitely not an overdrive, so don’t be surprised when you can’t get that bluesy tone out of it. It is a Heavy Metal distortion and very good one in what it does. The clipped frequencies stay consistent and the distortion is overwhelming and crushing – yet still defined. Color Mix is effective pair of controls, and with these the tone can be tweaked to match your guitar and your favourite frequencies. I still think you’ll want to max all the controls and learn a Entombed riff or two. I don’t blame you.

Here’s a quote from original marketing material: “Also, the HM-2 can be effectively used even with a single coil pickup guitar with low output level, because of its high gain.” – No disputing that.

Some of you know that i like MD-2 Mega Distortion a lot. This one could be considered as MD-2’s ancestor witth HM-3 Hyper metal on the on the same linear line of evolution. That would be a lot closer analogy than bringing MT-2 in to this equation. Super high gain usability. There’s a lot of crushing for this circuit to do yet.

Colorless writings, part 11 – The Expert

Wednesday, May 28th, 2014

What now?

I felt like i needed to write this off my chest. As the title suggests i’m going to rant about these so called “experts” that think they know it all and how i think we all should use caution when we assume we have an “expert” on our hands. First of all. I’m no expert. Sure, i’ve built hundreds of effect pedals, repaired and modded a bunch of units and done some analysis on a few boxes. That does not make me an authority on the subject. I’m still learning new stuff every single day in my chosen field, which is rather narrow when compared to vast number of electronic devices designed and manufactured over the last century or so. I do not know everything and i think i never will. I do know a lot, but damned be the day when i crown myself as an “expert”.

Let’s take a look at the definition of the word. “An expert is someone widely recognized as a reliable source of technique or skill whose faculty for judging or deciding rightly, justly, or wisely is accorded authority and status by their peers or the public in a specific well-distinguished domain.” (Quote from Wikipedia).

Now, if and when someone considers him or herself as an expert, we all can judge that expert by the work we see. As the effect pedals are very narrow field when compared to anything, there are bound to be these “experts” who write books on the subject with very little real knowledge about the filed. With well done research anyone can write sufficient book on any subject. Does that make the author an expert on the matter? No. It doesn’t. What if the research part has been light and sloppy? Does the resulting work help anyone? Here’s the bigger question.

Nearly a year ago i bought a book on pedals. It was called “Practical handbook” for effects. The author had done nice research on the history of how effects came to be and there are about a hundred pedals listed with superficial descriptions. Most of the dates are fuzzed or obscured (even worse than what i do on my pedal posts) with a decade as an error margin. Granted, reliable information on certain effects is very hard to find, if not impossible. But the pretext as an introduction on the book says something peculiar. The author claims he has had about 50 effect pedals in his posession over the years. Apparently the publisher of that book considered the author to be an expert to the degree where its ok to publish his book on the subject. He doesn’t claim to be an expert de facto, but as an author of “Practical handbook” it’s rather safe to assume someone considers the author as an expert.

So you’re pissed off by someone writing a book with moderate expertise?

Almost. Think of it like this – should i write a book on raising children? I don’t have any of my own, nor i ever will, but i’ve spent some time with our bass player’s kid and even more time with my sister’s kids. So i could claim i know a few things about raising a child. But would i be any expert to write a book titled “Practical handbook” on the subject?

Other issue with the book are the technical examples. It clearly says the example schematics are not intended as a base for your own effect circuit. There is a simple reason for that. I bet they were afraid of the possible copyright issues of schematics that were completely redrawn – so they simply made every single one defunct. I could tell just by looking at the drawings – No. That won’t work. And while making the schematics are defunct, the author removed or messed up parts of the blueprints that are crucial for the function and sound of the original design. So in a sense, the technical part is completely unusable and doesn’t teach the reader anything. Needless to say i felt pretty swindled after reading the book.

Would you feel any different if the book was titled differently?

Yes i would. It should be titled “Beginner’s guide” or “Simple overview”. Then the customer buying the book would not be disappointed to these hights. There are true experts. All you need to do is log yourself in to Freestomboxes.org and start reading. You’ll notice a few screen names that offer a lot of useful information based on facts and not on guesses. It is an open forum, so there is bound to be some not so great writings as well. Still, you can learn a lot from these guys. I sure would like to read a book on pedals written by one of those gurus.

Besides. I’ve never heard them call themselves an experts.

I think the main issue here is that publisher honestly thinks guitar effects as “toys” rather than real tools of the industry. This is where i believe it all went wrong. When you don’t respect the field, how narrow it may be, you are easily tempted by selling some half ass semi-truths as facts. In full view, i’m not blaming the author, but the publisher. Putting a person with hands on experience with 50 pedals on a  pedestal as an expert isn’t probably the wisest move. I did not mean today’s colorless writing to be a book review, but i wanted to poke the issue of who gets to be celebrated as the expert. As the Wikipedia noted, the Expert needs to have accorded authorty by his or her peers. And no one should ever call a slight introduction a “Practical handbook”. As another parallel, think of a book on math called “A Practical handbook on derivation”. You come home with it and read all about how numbers came to be and how you can add one plus one. In addition it has wide range of example equations – all broken and not true. How much can you learn from broken data?

The book itself isn’t that horrible. It is a nice introduction for beginners, but as a hard fact book that offers knowledge – not so much.

Ibanez DDL10 Delay II

Monday, May 26th, 2014

DDL10

What is it?
Ibanez DDL10 Delay II from Power series. Made in japan around mid 80’s.

Power series has way too many delays. What makes this fact even more sad is that these are all interesting designs. And most of them differ from others, so it’s a painful series to collect. To begin with, Delay II has delay time ranges from 19-113, 38-225, 75-450 and 150-900 milliseconds. This is in addition to standard mix/time/feedback controls (they are called D-Level, D-Time and Repeat here). Nice range indeed. As the first gut shot below shows, the processor is MC4101F, which we can find on other Ibanez delays of the era as well. This unit also features a clean parallel output, so the delay can be mixed in later in the path…

DDL10-guts1

Ibanez isn’t the best known brand for their full on recycling of board designs as many other manufacturers. Of course there are exceptions here and there where same board design has been rotated throughout different series and re-branded designs along the way. I have not counted the total of Ibanez/Maxon designs in existence, but the number should be somewhere around well over 200. For the six delay pedals in  Power series, which was produced for a brief time in mid 80’s, we are bound to find some recycling. I still am assuming that the recycling of board designs for Ibanez is a low percentage. At least if we compare that assumed number to DOD board designs, for example. This model shares the board with one of the DML (digital modulation delay) designs. Somehow i think the “DDL” sticker to indicate on which design this board was meant to be used, is sympathetic.

DDL10-guts2

Once again i’m forced to leave this article somewhat a stub due to my limited knowledge of these massive digital designs. Nevertheless, i can’t find a lot of negative things from this pedal. Not from the inside, nor the outside. As the units are reaching vintage age, the price of a unit in good condition is something interesting to follow. All of these are well made units and will withstand years and years of more use. Even the design is complex, i still see a long life for these boxes. Definitely a prime example why Ibanez (ok, Maxon) pedals are appealing to me.

How does it sound?
Great. There’s no super cold metallic feel to the repeats in the same manner as most digital delays of the era have. Instead there is a certain analog feel to the sound. Ibanez has succeeded in this behavior in more than one or two pedals in their vast catalog of delay designs over the years. This unit is no exception. Well working controls with wide range of setting in addition to as natural digital delay sound as possible. There’s not much to add, but Great delay. The capital G is there for a reason.

Danelectro DJ-16 Bacon ‘n’ Eggs Mini Amp/Distortion

Friday, May 23rd, 2014

DJ16-BaconnEggs

What is it?
Danelectro DJ-16 Bacon ‘n’ Eggs Mini Amp/Distortion from Dano Mini series. Made in china around mid-00’s.

This was difinitely one of the Danelectro units that i didn’t have much interest towards. But as collector, i didn’t have much choice but to get one. This unit i got cheap from the local music store. It was cheap to begin with, but the personnel at the store had misplaced the original cardboard box, so i got it even cheaper. First thing that occured to me was that this could probably be used with the pedalboard meant for the series as a last unit. That way one could have a tuner, three effects and an amp in one easily carried box. Yeah. I know. The tuners suck, but still that could be something fun. Tried this out at home and noticed a few things that piqued my interest.

DJ16-BaconnEggs-guts

First of all, the unit acts as an amp when there is no cable at the output jack. Second, the amplification is done with single chip and with amplifaction on, one can’t turn off the distortion. That is a lot of SMD connections on a board that small. The bypass works when output cable is attached, so part of the circuit must be for that too.

As an practice amp? No way. Strange bird of all the effect pedals? Yes. Strange thing to be in existence.

How does it sound?

As an amplifier – horrible. 9V supply is doing everything it can to provide something like 2 watts of sheer power, which is then pushed on to a two inch speaker. The resultin “tone” is harsh, loud, cold and about a hundred worse adjectives. But. When used as a distorion effect pedal and the amp feature disabled, it’s not bad at all. Should it be used on your rig to give distortion? You might want to try it out, but my guess would still be no. In general, the distortion sound and feel is quite close to a control-less, maxed out MXR Dist+ with some peorsonal character in it. Not bad. Still a bit strange thing to be using in any setup.

Ibanez TC999 Tube King Compressor

Tuesday, May 20th, 2014

Ibanez-TC999

What is it?
Ibanez TC999 Tube King Compressor made in Japan in the 90’s.

It’s been quite long since i got this unit and took the photos (so sorry about the quality). Got this as semi-functioning unit in a trade. Problem was with the enormous amounts of hiss and interfecence when pedal was engaded. Dirk has posted a schematic up on his site, and i follewed that to see if power supply filtering had gone bad. Nope. Since the hiss was still there after i swapped the filter caps for new ones with same value, but higher voltage rating. Surely, the design isn’t meant to be used with a battery, but it did occur to me to try out the simplest possible diagnostic for power supply issues. Run it with a battery and see if the noise goes away. Yup. It does. Problem solved. Do not use a crappy power supply with this one. Some noisy squish is still present on high sustain settings, but i suspect that to be a feature. Other issues with pedal were your standard non-pedal enthusiast home made fixes. Like fastening the jack with superglue after someone had taken the threads off from the jack. Never. I mean Never fix anything with superglue nor hot glue. Please. Two of the knobs are not original, but that doesn’t slow us down too much.

Ibanez-TC999-Guts1

Mini analysis of the design shows that the tube is there to offer the BA6110 VCA SIP chip the pre-compressed tube sound input that a good compressor wants. Dynamics of the voltage controlled amplifier is better (at least in theory) than with the standard silicon amplifier. No, the tube isn’t creating the compression. The tube is there to provide enhanced dynamics for the otherwise near standard modern Maxon/Ibanez compressors with VCAs. For the controls, the Sensitivity is basically a gain control before the tube grid. This sets the amount of signal passed to the tube. Attack and Sustain are controls for the VCA parameters, more or less the same as we’ll find in Soundtank compressors. Master is your overall volume control. The stomp switch for Boost sets the input gain of the tube for two different settings. Pretty straight forward.

Ibanez-TC999-Guts2

Two stacked boards look like most Maxon designs from the 80s and 90s. Neat, but somewhat dull. Overall, it is a compressor that has some good thinking and engineering involved in its design.

How does it sound?
Loud and mellow compression, with some noisy squish when sustain is maxed. The boost isn’t as clean as i hoped, but it’ll be enough for many purposes. Design part left me a bit puzzled or hoping to get more out of it. Guess it’s safe to assume that new ideas do not necessarily go hand in hand with “better”. It’s not bad sounding compression, but you’ll be better of with Ibanez CP5/CP10/CPL, Digitech Main squeeze or Marshall Ed. But yes. It has a tube in it. You’ll need to weight if its Mojo or brutal usability you’re after. You’ll get a better sounding booster out of almost any cheap boost pedal.

Yamaha COD-100 CMOS Overdrive

Friday, May 16th, 2014

Yamaha-COD100-CMOS-OD-1

What is it?
Yamaha COD-100 C MOS Overdrive from Yamaha 100-series. Made in japan in mid to late 80’s.

Happened to score one of these in near mint condition with an original retail box from a local guitar builder guru J. Lindén. Since i’m still fond of those coin-op design Sound Device series pedals, this one wasn’t too high on my want list. But. Price was correct and due to like-new shape with nearly 30 years of age.. How could i resist? Surprisingly little information available on the unit. Your best bet would to check out the specs from original marketing material at Effectsdatabase.

Yamaha-COD100-CMOS-OD-guts1

Before opening the unit up, i had a huch of this being adaptation of either EHX Hot Tubes (which has a history of its own) or Ibanez MT10 Mostortion. Turns out its neither and both. I suspect that the lower IC is there for electronic  bypass switching and the part above the jacks is the effect circuit itself. There is unbuffered 4069 CMOS chip in there. I’m currently just guessing what’s going on with the circuit, but this pedal may be one of those that deserve a deeper look at the design. The board design itself is eye pleasing, but not special. Nice. Not shocking, but nice.

Yamaha-COD100-CMOS-OD-guts2

I’m quite puzzled how Yamaha designs have slipped through the cracks of interesting designs. Most of the effects that people find interesting from the era have factory schematics floating around. But not for Yamaha. Even the traced schematics for these are scarce. For this particular unit, i sure hope there will be interest in the future. Expect an update on this post…

How does it sound?
As advertised, the MOSFET sound is in there. Harsh, metallic overdrive/distortion with plenty of output level. Well working EQ section with separate controls for highs and lows. Pretty standard all the way, except for that MOS sound. Since there are only few of similar sounding designs, i’m forced to wonder if none of them sold well? And if so, why? For my ears these all (this, WH Red Llama, Hot Tubes and Ibanez MT10) sound very good, gritty, agressive and powerful. And we do have ZVex Box Of Rock and Distortron which both have similar characteristics in their sounds.. I’m under impression that those sell well.

Well. Doesn’t matter. To me, this sounds like a lost gem and it is a definite keeper.

EHX Satisfaction Fuzz

Tuesday, May 13th, 2014

EHX-SatisfactionFuzz

What is it?
Electro Harmonix Satisfaction Fuzz from Nano series. Made in USA in early 2014.

Noticed this unit’s release on the web and it seemed quite promising. Seems like the idea behind the design was to recreate that well know fuzz sound from one well known Rolling Stones track. According to the stompbox historians, the unit used on the original track was in fact one of the early Maestro Fuzz Tones. Solid idea to recreate that sound. These unit sell for cheap as new, so there wasn’t much choice for me but to get one. Of course i teared it right open as soon as it landed on my desk.

EHX-SatisfactionFuzz-guts1

Modern EHX design. No surprises there. Super dull and extremely boring design. But wait a minute! What are those empty pads just above the input jack? C7 and D2-D3. Print next to those holes say <++clip> and <++bass>. Now that’s something you don’t see everyday. As there are no hidden components on the other side of the board, i thought this should be easy enough to trace. So i did. Does that look familiar to you?

EHX-SatisfactionFuzz-guts2

Yes. That is, in terms of topology, pretty much 1:1 with good old Jordan Bosstone fuzz with NPN/PNP pair as the main attraction. Design here has nothing to do with Maestro Fuzz Tone. Only a few cap value changes to Bosstone and voilá, there’s your new design. Smaller values for input and output caps, plus missing diode clipping at the output are the main differences, but EHX has cleverly left us with six empty pads and clear instructions what to do. Upping the output cap for 22n (10n and 12n in parallel) and adding two silicon signal diodes for clippers makes this so close to the Bosstone that it makes this unit very, very interesting. I think this would be the greatest and cheapest way to get yourself a Bosstone. Buy yourself a cheap EHX fuzz and add one cap and two diodes.

I’ve heard stories about some synthesizer makers leaving empty pads for user to try mods on. But i’ve never before seen this behavior in guitar effects before. I do hope this is something that we may see again in the future, maybe even from other manufacturers too. This does make EHX look better in my eyes…

For my own unit, i tried on the clippers, but decided to leave them out. I did place a 22n cap for C7. Now it isn’t exactly EHX Satisfaction nor Bosstone. (Maybe i should try it with only added diodes, but no cap at some point..)But it is something useful. And to be frank, it is cool.

How does it sound?
Out of the box – not so super. It has some qualities that could be reminding some of us of that desired Satisfaction tone. Thin, loudish, but not mushy enough fuzz. With output cap value increased – wow. Added body and mush. Think of mushroom clouds viewed through a kaleidoscope. Yup. It sounds like that. Fat, massive, loud and devastating fuzz. With both, clippers and cap added, it sound pretty much exactly like all the demos of original Bosstone i’ve heard. (Yup, i haven’t had a pleasure of playing with the original Bosstone unit. At least not yet.) Overall. Satisfaction Fuzz sounds good and it is definitely worth the money.

DOD FX80B Compressor Sustainer

Monday, May 12th, 2014

DOD-FX80B-CompSust

What is it?
DOD FX80-B Compressor Sustainer from XF-series. Made in USA in 1988.

This pedal had been on my want list for quite some time. The biggest reason for simply not buying it was that these units sell for ridiculous prices here where i live. The one man (wikipedia link in finnish), who is deservedly considered as finnish guitar god used one, so it is in everyone’s interest to ask for way too much for these units. No matter what the condition they are in. For me, the idea of paying what these usually go for wasn’t too appealing. So i was looking for one on ebay and found this unit as broken one. Since the battery door was in tact and the pictures showed an unit that was in good condition, i snatched it for about the half of the money what people usually ask for these here. On the item description it said only that the dc-jack was missing, but the unit was in perfect shape otherwise – and it was working with a battery. Once the unit arrived i checked if the DC jack was missing or what was the problem. There wasn’t any. Only thing missing was the nut ot the jack. The jack itself was inside the box, still wired and in working order. Went through my box of crud and found a nut that fit. So, with basically zero repairing work, i got myself a “Pulliaiskompura” for a very nice price.

DOD-FX80B-CompSust-guts1

As always, there are nice collection of information about the unit at America’s Pedal. And here’s a original factory schematic of the earlier model with middle pot labeled “Attack”. The circuit is more or less the same on earlier and later versions. Either way, it shares a lot in design with original MXR Dyna Comp, including CA3080 OTA on board.

DOD-FX80B-CompSust-guts2

Board design and everything else is pretty much the same with all the other FX serie pedals from the era. A battery door that can easily be misplaced (Someone should make a batch of these doors as a spare parts – there could be some real money in that. Hell, i’d buy 5 immideately.) and the DC jack takes only 3,5mm positive tip supplies. Standard DOD flip-flop bypass and so on.

Edit! I studied the two available schematics a bit further. While the circuits have similarities, i think it’s worth noting that version with “Attack” control is based on CA3094 OTA, while the later one with “Release” control is based on CA3080. This means that there are distinct differences between the circuits and the latter version is somewhat closer to other OTA-based compressors around than the former. Haven’t had a pleasure to compare the two side by side, so i can’t be sure how big of a difference these changes are. Schematic for the unit above can be viewed here.

How does it sound?
For the later, “Release” version – Soft, transparent compression that one easily forgets that it’s engaged. The difference kicks in once it’s turned off. In my personal opinion, the sound is definitely one of the best for a OTA-based compressor i’ve played with. So the reputation isn’t false. Where as most of the CA3080-based compressors feel mushy and noisy, this one keeps the excess hisses mostly away. Sure, it doesn’t sound nearly as good as optical compressors, but for OTA-based – this is the king.

Korg TNB-1 Tone Booster

Friday, May 9th, 2014

Korg-TNB1

What is it?
Korg TNB-1 Tone Booster from Series 1. Made in japan in late 80’s.

Korg hasn’t produced many guitar effects, but they are well known for their high quality synthesizers and other products. In fact, the Series 1 is just a rebranded Yamaha 01 series, both manufactured by KLM. Or the Yamaha series may by simply a rebrnaded Korg series. Hard to say, but to me it seems like KLM may have been offering various designs as OEM boxes for more than just two brands. Of this i’m not sure, but the designs show a lot of resemblance to those Pearl effects. All the way to the enclosure design… (Nope! “KLM” means the board is designed and built by Korg Japan, the other manifestations of the KLM circuits in other brand pedals are OEM’d Korgs. This was just brought to my attention and i was not aware of this before, thanks to Pepe!) Got this one in near mint condition and with original box. And for a good price, so i couldn’t let it go. I had studied the schematic earlier on and this seemed like a great preamp/distortion box. Schematic has “KLM690” printed on it. I’d be rather interested to know what other brands have bought OEM designs from that company…

Korg-TNB1-guts1

Really solid enclosure that is fastened through the top rather than from bottom. Relatively small board footprint and comes with dreadful asymmetry. Despite that, i think i’m just going to go with saying that the unit is very well designed and built. It’s not offering any high gloss eye candy on the board design, but i think it should handle heavy use for a long time.

Korg-TNB1-guts2

To analyze the schematic, there is input buffer that splits the signal for bypass buffer and the first driver stage. The bypass buffrer outputs to DPDT stomp switch and while it has two buffers on in bypass mode, i didn’t notice any of the sucking. With a short testing, that is. Anyway. The first driver stage is non-inverting opamp stage that has similar gain control that you’ll find in OD250/Dist+, only with 1M reverse log pot. This should give out more usable sweep for the pot and it does. This gain stage can be cranked to massive distortion. The stage drives a simple two band tone control which then passes the signal to recovery gain stage and volume control. I’d say the original designer has put the TL072 in good use. The recovery gain stage is inverting, so the wave coming out is inverted. This is not unusual, but something that user might want or need to know.

Korg-TNB1-guts3

I find the bypass method interesting. Simple but effective. While the bypass buffer always gets the signal in, its output is switched between effect and bypass. Other pole of that switch either kills the gain stage or lights up the LED. It may not be anything super special, but it has some out of the box thinking involved. This is a very nice unit to have.

How does it sound?
From mild preamp to massive distortion with well working EQ section. Good ouput level and usable range from unity tone shaper to singing leads. It sounds good. No denying that. I’d still call this an distortion rather than a conventional booster, it offers nice versatility in tone. Good sounding well built unit. I do not see any downsides to this one.