Archive for the ‘FX-Series’ Category

DOD FX25B Envelope Filter

Sunday, June 8th, 2014


What is it?
DOD FX25B Envelope Filter in “final” US DOD enclosure. Made is USA in the late 90’s.

Grabbed this one off from eBay as the price was correct. I was totally expecting a V-serial unit for the price and once this thing arrived and i opened the box – no type plate sticker. Damn. But there wasn’t a “made in china” stamp under the DOD logo on the rubber mat either. I still wasn’t convinced. So i headed over to America’s Pedal site and checked the info for the FX25B. What do you know. All the components are exactly as depicted in the AP’s article. Check here to compare. But then again.. From the article, i get the impression that the FX25B was never issued as a chinese VFX unit. And furthermore, there are apparently only three Final Series designs that never went on to VFX, namely FX91, FX84 and FX25B. Funny how you learn something new every day.


The design is evolved FX25 with added blend control. This control was probably added so the effect would work better on bass. On the board design point of view it is the usual, dull modern DOD design with nothing special in there. There is a schematic up at FIS. Should be worth noting that the filter is created with LM13600 OTA. Trigger driver is JRC4560. TL072 takes care of the mixing and blend control. I can’t recall any other OTA-based envelope filter right of the bat. I’m sure there are some though.

Well. I’d like deconstruct the working idea behind all envelope filters. First of all, we’ll need to split the incoming signal in two. First splitted signal needs to be sent to filter and the other to trigger.  Trigger needs to have some sort of threshold so it knows when to trigger the sweep. When the incoming signal for the trigger is strong enough, it will pass voltage to LM13600 control pin in a sweeping manner. From that signal the OTA knows to modulate the frequencies of the signal passing the filter. Filters come in many forms, shapes and sizesall of them have components to determine frequency and gain of that frequency. OTA-based filters are usually used due to their capability of offering tight frequency ranges with reasonable amount of components around it. All methods can do the same thing, but different methods result in different tones while the working idea remains.

How does it sound?
Nice. Not squishy or mushy. Straight up clean filter sweeps all the way. As basic analog envelope filters come, this takes its place in top 5 with ease. The frequency ranges this circuit can sweep are good for most instruments. Haven’t tried this with a synth, so i can’t be sure if it will stay unchoked when driven with line level signals, but it is very well working and good sounding envelope filter for guitar and bass. Low noise floor and even lower noise on the sweep make this very attractive effect. Recommended as top shelf quality sounding effect.

DOD FX80B Compressor Sustainer

Monday, May 12th, 2014


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.


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.


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.

DOD FX12 Tuna

Thursday, April 10th, 2014


What is it?
DOD FX12 Tuna. Guitar and bass tuner pedal. Made in USA around 1996-98. The enclosure is in line with the last US made series and the original box doesn’t have “made is USA” printed on it. There is no chinese made “V” version in existence. I’m thinking that the box was designed without “made in” notion, because it was planned to continue manufacturing FX12 in china with other VFX models.

DOD Tuna is one of the first pedal tuners to hit the stores in 90’s. The idea and purpose is there, but the reason why these units were basically butchered in sales when compared to Boss TU-2 is clear. It is a bad tuner. Collectible? Maybe, but a useful tuner? No. Also, that may be the reason why this design never made it to the chinese mass production in the end of 90’s. The fishnet paint is cool.


The guts seem well made and the aesthetics of the whole pedal are nice. It’ s not bad looking box at all. But sadly, all the good things end there.

How does it sound?
It’s a tuner so it doesn’t exactly sound like anything. It’s not even supposed to. It’s supposed to show you the frequency and note on the LEDs. It does that. Sort of. When i tried to tune my guitar with this unit, it showed every string to be in tune. When i strummed a chord.. No. Annoying little thing. I’m keeping this as a collectible novelty and a historical item. But to use it? One needs to be completely insane to even think about using this on his or her board. It is crap.

DOD FX69 Grunge

Thursday, December 19th, 2013


What is it?
DOD FX69 Grunge, made in USA around 1995. Board revision is “B”, but the box is per 1993 version.

The DOD engineers were probaly after the sound of Kurt Cobain’s Boss DS-1/DS-2 and the Mudhoney fuzzes that were taken over the top. Or then it was just a plan to make a lot of money out of the genre that hadn’t too much to do with the pedal’s sound. There are conflicts between the sources about mr. Cobains use of this make. I personally feel that the most accurate version of the truth is told at Kurt’s Equipment website, stating the Nirvana’s guitar tech as a source for the information. So the throwing the pedal at the audience is probably just a myth. May it be what ever. Let’s check the pedal itself out and not focus on who did what 20 years ago.


There’s standard DOD electronic swithching and lots of gain stages and filters. Schematic is available online and it shows the signal path to be buffer -> filtering gain stage -> passive filter -> main gain stage -> hard clipping -> dual gyrator filter stage -> tone control (active lows and passive highs) -> one last driver for tone control -> output buffering. Yeah. Simple. But all that is needed to create horrid amount of gain and keep the audible oscillation and too much excess noise from completely ruining your sound.

So it’s a fairly complicated super high gain distortion with reasonably good eq section. Does it really depict the sound of the genre? Probably not. DOD already had numerous “metal” pedals in its lineup. What makes this all special is the fact that marketing is completely in reverse. Most of he ones that are branded as metal distortions are lower gain devices and FX69 Grunge is definitely at its best when used for metal distortion tones. Now, who of you metalheads want to use pedal with “Grunge” written on it for your lead sounds? How come i see no hands raised…

How does it sound?
Weird. At the same time amazingly good and utterly bad. Very few “standard” designs leave you feeling this baffled. Maybe it’s a good thing to get feelings out of a pedal. At least it does raise an opinion out of almost everyone. You’ll either love it or hate it. There’s no meh-factor on this one.

If you are after that buzzsaw sound, then the Grunge may be just the right pedal for you. It’s even underrated and highly praised at the same time. DOD grunge – the paradox of all well selling pedals. I’m basing the sales argument on the fact that Digitech is still selling the same circuit on its D-series, which makes the design over 20 years old and it has apparently been on the market since the initial release in 1993.

DOD FX60 Stereo Chorus

Monday, November 11th, 2013

DOD-FX60-STChorusWhat is it?
DOD FX60 Stereo Chorus. Made in US around 1990-91.

For some reason i find this unit simply beautiful. Seafoam/baby blue colour and simplicity of two knobs. Even the straight DOD logo suits this look very well. For aesthetics, this is one of the finer examples why i happen to like these FX series pedals so much. There is an old factory schematic available online which doesn’t quite match this unit’s version.


3101/3007 design. Basis of the design has remained, even though there are reportedly at least five different versions of the board. At least the delay section with that particular BBD pair is the same on all of them. This unit is the second latest board design, sharing the board with FX65. Which i do find intriguing, as the stright logo label would have us to believe that the unit would have earlier board in it. Ah, the mysteries of DODs. More quirks on the FX60 and all the different board revisions/versions – read about them on the DOD information heaven, the America’s Pedal site.

Overall, it has your standard controls of width and speed. Both having nothing but usable parts on the range.

How does it sound?
Mellow and soft. Like a good simple analog chorus should. There are no extreme settings, but just plain and simple warbling mild chorus. Very usable, but with no recognizable personal character. For a cheap DOD pedal, you really can’t or won’t go wrong with this one. It does sound very good, but doesn’t make it in to the top three for me.

DOD FX33 BuzzBox

Thursday, October 17th, 2013


What is it?
DOD FX33 BuzzBox, made in USA around 1995.

Now here’s something you won’t see everyday. When something is worth overdoing, let the DOD engineers show you the real way of the beast. Design is just sick. The America’s Pedal article on the history of the design is a very good read. There is a schematic available online, named Leafblower. It’s drawn by Celadine and it is spread accross two pages. It’s not that complicated, but still a big design.


So in fact the design has distortion and octave divider in parallel, which is nothing too special when compared to other low octave divider circuits around. But this time the voicing and gain are set quite perfectly for extreme buzz. The controls work well, even though the names are gibberish. Heavy is controlling the mix between distortion and low octave output, Buzz acts as distortion control, Saw as tone and Thrust is your overall output level.


As a nice curiosity, there’s a sticker inside with ” Dana B 232″ printed on it. These units usually sell for a lot. I happened to be quite lucky and got one from a friend in a trade that was good for both of us. Thanks Markus.

Due to the circuit being more complicated than its peers, it’s not your average suspect for cloning. After all, there are three dual opamps and a CD4013 flip-flop in addition to a few transistors and clippers. But from economical point of view a reissue should be welcome.

How does it sound?
Massive low octave noise monster. Some folks claim it to sound like a Rat driving a Bluebox, but to my ears it’s not even close. Think of two DOD Grunges in parallel and blasting the resulting hyper distorted signal through quadruple bass booster that has all the frequencies divided into lower octaves ála Bluebox. Yes. It is that sick. in the same time this sounds like a mash of a leafblower, a vacuum cleaner and a demon possessed NES system on speed.

DOD FX66 Flashback Fuzz

Monday, October 14th, 2013


What is it?
DOD FX66 (V) Flashback Fuzz. Made in china around 2000.

DOD has only produced two fuzz pedals in all of its existence. That’s not much. Plus both fuzzes in DOD back catalog are not fuzzes in traditional manner. Neither of the designs are transistor based, nor rely on own unique design. Both of them are rehashes of previously released circuits and they share PCBs with their predecessors. Where FX52 is basically a revoiced FX50B, the FX66 Flashback Fuzz is revoiced FX66 Grunge. A few interesting details can be read at America’s Pedal website. Lack of 6 components and some value swapping can apparently make a completely new effect.


Note that the board has FX69 printed on it. Funny how tweaking the board really changes the characteristics. This doesn’t share anything else with the Grunge, except for the PCB, electronic switching and power filtering. Don’t know how the engineers at DOD pulled this off, but the result isn’t that bad.

In reality i was after the first production run US made unit, but this one was the only one i could find. And it suited my wallet too.

How does it sound?
Not bad at all actually. There is definitely some of that Fuzz Face analog feel in there, but it’s not really that close. It sounds more clinical than simple FF circuits, while still remaining quite musical. There is a lot of fuzz character in its sound, which is amazing as it still has nearly the same topology as FX69 Grunge. Quite usable, even though the uncontrollable overtones and glitching scratches are limited to minimum with all opamp and clipping diode design. I would personally recommend trying one out if you get a chance.

DOD FX57 Hard Rock Distortion

Friday, September 6th, 2013


What is it?
DOD FX57 Hard Rock Distortion. USA made box, dating 1987.

Bad year. 1987 i mean. According to DOD information heaven, America’s Pedal website, the basic idea for this design was already tried out on certain DigiTech double pedal, as well as on one Boss design. And what is this idea? To take a OD/Distortion and place a delay circuitry after it to “widen” or “thicken” the sound. I must say that the idea itself doesn’t sound that bad. Distortion with analog delay? How could that be bad? Well it can. For those interested, the schematic can be found online at Schematics Unlimited. It shows that the delay section is placed  after the main gain stage and to be mixed back to the distorted signal at the level control. The delay itself is created with MN3007/NM3101 pair. Level control is mixing the signal, delay included or not, with virtual ground and passing it to the presence control. The distortion control is basically just a variable resistor limiting the input signal current after the mandatory input buffer – which is needed due to basic DOD electronic switching. There are two trimmers that affect the delay functionality.


The board looks kinda cool with those yellow mylar caps.

Now what exactly makes this a bad design? Two things. The distortion and the controls. That is a lot for one design. With the soft clipping, placing four Si diodes to the feedback loop of the gain stage offers something that isn’t too far from tube screamers, but the filters and second clipping stage (the Ge diodes) before the volume control gives out texture that isn’t too desirable. And that presence control would need a huge rework to even remind me of anything reasonable.  I personally think that presence is just a wrong word for this control. It should rather be “extreme bass cut pot that we here at DOD didn’t think all the way through”.

How does it sound?
Bad. Thin, hollow and nasal. Turning the delay off doesn’t quite help you. With the distortion at minimum and delay maxed, we can get something that reminds one of usable sound. But it is pretty crappy sounding design. Not all the settings are awful, but none of them are particularly good wither. Overall experience is so crappy, that i have high hopes for this becoming a rare gem – due to low(ish) number of units manufactured in relatively short period and the fact that some people will dispose their units with their everyday garbage. Which wouldn’t be too crazy idea with this particular unit. Not all of the setting combinations are horrible, but in genereal; it sucks and it sucks hard. But it is an interesting failure.

DOD FX52 Classic Fuzz

Wednesday, July 24th, 2013

DOD-FX52-ClassicFuzz.resized What is it?
DOD FX52 Classic Fuzz, Made in USA in early to mid 90s. Yup. It seems almost like yesterday when boxes of this series were in every young guitarists hands. It’s been 20 years already, but i wouldn’t exactly call it “vintage” for another two decades though.

This model was discontinued in 1998, and my units serial number points to manufacture date being close to first quarter of 1994. It’s not a perfect pedal in any way. The most interesting thing is that this one has the same PCB as FX50. Only a few component values differ and one clipping stage is omitted. There’s a lot of good info available on this circuit on the America’s Pedal site. You can find the schematic hosted at Experimentalists Anonymous, if you want to see it. Schematic shows a few things one would want to mod. Not going into that right now – as i would need another unit in my collection before i would dare to ravage one of these. Things i would do to her would be; adding a diode pair to the feedback loop of LF353, tuning/upping the gain on the tone driver half of that IC and probably doubling the hard clipping diodes and removing the 1n cap taming it. One could also tune the 22n and 10µ caps to their taste of tone control. Maybe even rethink some pot values and tapers.


Chips not affiliated with bypass switching are LF353 for the gain and tone stages and JRC1458 as in and out buffers. Also. Note the unconnected components left from LF353. As you can see from the shot above, the model is marked on the board with permanent marker. Here’s another photo that shows what’s under the filter cap:


So it’s built on FX50 PCB. According to internet, it seems that there are other models sharing the same board too.

How does it sound?
To be honest. I’ve heard a lot of better circuit designs. Where DOD advertised this with the spiel “The FX52 Classic Fuzz duplicates the sound of the early 60s distortion boxes, such as the Fuzz Face and the Fuzz Tone. A must for musicians looking for a more nostalgic sound.” – I Do not find the resemblence to Maestro or Arbiter fuzzes mentioned. It’s more compressed than Big Muff, while that would be the closest vintage circuit. I still can’t hear the Fuzz in there. It’s much closer to being just muddy distortion than a real Classic fuzz. It has decent output level and better-than-average sustain. Might keep it in my collection, just in case. But i don’t see myself fastening this to my pedal board anytime soon. Or maybe i should mod it after all…  Good thing you can get still these for cheap, at least at the time of writing.