Archive for the ‘DOD’ Category

DOD FX100 Even Harmonic Overdrive

Wednesday, July 23rd, 2014

DOD-FX100-EHOD

What is it?
DOD FX100 Even Harmonic Overdrive (with Integrated Tube (TM) Technology. Made in USA in 1997.

Of course i was curious about this new and exciting thing called Integrated Tube (TM), or I.T. (TM) technology. What it actually is – it is how marketing department takes random words, put them one after another and place (TM) after it. Sure. It sounds very good and interesting to many to see new technologies arise and be put in use. And in this case, what does the I.T. (TM) really mean? There is a JRC4558 dual opamp in there. So my next question is, “Are you kidding me?!?”

DOD-FX100-EHOD-guts

Actually, the two dual opamps it this late ’97 or early ’98 unit are JRC4560Ds. So apparently the I.T. (TM) doesn’t mean even that. Now let’s put the disappointment aside and check the schematic. Your guitar’s signal journeys trough a FET buffer and reaches a gain stage with Drive control on it. Then we have another FET/BJT gain stage followed by a strange world of single diode clipping (note to self – do not pay big money for FX101, as that is the same circuit, without I.T. (TM) and with a single diode added). Journey continues through a dual gyrator circuitry, which also is a home to Lows control. On the path comes a passive highs filter with a pot on it. This is also the place where we’ll have the volume control. After this, the journey is about to end. We have only make-up gain stage and amp simulated output stages left.

So did this journey warrant any claims for new and exciting technologies? No. Was it really worth it to get (TM) status to something that’s already been done over and over by just about every manufacturer?

Further reading on America’s Pedal website

How does it sound?
Ok sounding overdrive with sluggish output level. I’d say the level is insufficient for anything else but very low, vintage output single coil pickups. Clipping doesn’t feel broken, but nice, warm and harmonic. Even. Lows and highs are controlled nicely, but this just isn’t a very good pedal. Oh. Yes. It’s just my opinion. It doesn’t mean that the unit would really suck. It just means that after the marketing department had its way with me, then come the real issues. Makes me wonder i should just solder that missing diode in and pretend this is a FX101.

DOD FX91 Bass Overdrive

Wednesday, July 9th, 2014

DOD-FX91-BODWhat is it?
DOD FX91 Bass Overdrive from DOD FX-series. Made in US around year 2000. No serial or battery door in tact, even though this late enclosure version has the door attached with a rod.

Bass overdrives are a fun genre. I’ve seen a few and nearly all of them are pretty standard overdrive circuits with no cut on the low frequencies. Which means that the designs may be slightly too fat for guitar, but i still think these should be tried on guitar too. America’s Pedal has some info about the unit. It apparently shares the circuit board with FX102 mystic Blues overdrive. There are more features for this version, which explains empty pads on both effects.

DOD-FX91-BOD-guts1

There is a schematic up on the web without the switching part. The drawing shows a buffer at the input, which passes the signal to pretty standard clipping amp and on to a Blend control which mixes the clean signal with the output of that clipping amp. That is followed by a tone stack and a recovery amp and a volume control. simple, but decent design.

DOD-FX91-BOD-guts2

Interesting little fact about these units is that at least some of the units have a factory error. The R3 should be 1K resistor, but some units have a resistor with 200R value on its place instead. This change adds a noticeable amount of gain coming out of the clipping amp, and it shifts the frequency around too. You can read more about it at DIYStompboxes forum.

How does it sound?
Fat and useful. Serves well as bass overdrive and the blend control works also well. There’s enough gain to get soaring blast sounds out. I’ve played with this with a bass and a guitar. Bass is obvious choice to use this with, but it offers very nice boost features for a guitar too. Reasonably  good effect.

DOD FX25B Envelope Filter

Sunday, June 8th, 2014

DOD-FX25B-EnvelopeFilter

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.

DOD-FX25B-EnvelopeFilter-guts

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

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.

DOD FX12 Tuna

Thursday, April 10th, 2014

DOD-FX12-Tuna

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.

DOD-FX12-Tuna-guts

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

DOD-FX69-Grunge

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.

DOD-FX69-Grunge-guts

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.

DOD-FX60-STChorus-guts

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

DOD-FX33-BuzzBox

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.

DOD-FX33-BuzzBox-guts1

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.

DOD-FX33-BuzzBox-guts2

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

DOD-FX66-FlashbackFuzz

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.

DOD-FX66-FlashbackFuzz-guts

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 Overdrive Preamp 250 (reissue)

Thursday, September 12th, 2013

DOD-250

What is it?
DOD Overdrive Preamp 250, 90’s reissue in yellow first series style enclosure. Made in china.

This is one of those boxes that everyone should play with at some point in their life. If for anything else, for the feel of that heavvy duty box. The base design topology is pretty much verbatim with MXR Dist+ and probably a hundred other boxes from end of the 70’s up to today.  There are differences though. And good thing there are. As in my opinion, modern Dunlop made Dist+ reissue with UA741 and Ge diodes just suck. But before anything else. Let’s just open this up and see what’s inside.

DOD-250-1guts1

Looks quite modern with neat thin circuit traces and connector. Plus the blue jacks. Sadly, no date printed on the board. I really wish that it had a date in there. Would make the guessing process less valid. Components are often good place to start the process. So let’s see what lies underneath that board!

DOD-250-1guts3

There is a dual opamp  in here!

Some documented units here at the internet have KA4558 chip instead of RC-branded one, so that should be a clue. Oldest Fairchild Semiconductor’s datasheet for KA4558 chip i could find is dated 2001, so i do believe that the units featuring Texas Instruments RC4558P are older than 2001. Drop a comment if you know the exact dates when these were made with KA and RC branded  chips. I’d be more than interested to know. The print on the chip is 66CRDYN, which tells me absolutely nothing. I’ve read that usual way for printing manufacture date on the chips is with four digits. Two for year in question and other two for the week of that year. Apparently not for TI chips.

The dual chip can be found only in these reissues. Original design is with UA/LM741 single opamp. Schematic for both versions (one with old single opamp and the one with dual opamp) can be found online, and checking them both out would be recommended. The dual opamp version just omits the other half of the chip completely by grounding the inverting input and shorting the output and non-inverting input. The other half is used as in original. So it is basically just wasting the other half, while staying true to the original.

The box itself is quite loyal copy of the original with the stamp on the back. But there’s also a aluminium sticker that tells us where this unit came from.

DOD-250-2backplate

How does it sound?
Just amazing. For me, this one sounds way better than any of the single opamp versions i’ve tried. I actually cloned this version of the circuit for myself and i’m using this clone on my main pedal board. Once cloned, i can have standard 2,1mm DC jack and an indicator LED – Wouldn’t want to harm my original to incorporate those features. I use it to boost the rhythm riffs on choruses. Just a tad of boost and mild overdrive in addition to my mildly overdriven base sound. It just brings the songs alive. In my opinion, this is just the perfect overdrive/booster. Better than all the rest. I know some people will disagree. And they are welcome to disagree all they want. I just don’t see myself fastening any other design to my board as an overdrive anytime soon.