What is it?
DOD FX53 Classic Tube from DOD’s FX series. Made in USA, 1991.
A unit that’s been mostly put down by the misconception about its design for decades. I know i was under the wrong impression for a long time too. The name may point to the direction of all the different tubescreamers and derivatives, but no. There is practically nothing from TS-family in here. If you don’t believe me, check the hand drawn, traced schematic up at FIS. I do get the idea for the name. The designer may have been after that certain accent on the mids, but that’s not the main thing for this design at all. Look at the first gain stage after the input buffer and the switching. It’s a cross breed with TS-style feedback loop clipping diodes and a 250 OD-style gain control. The diodes in the feedback loop is the only thing bearing any resemblance. This driver stage is then followed by a hard clipping stage before the volume and the tone controls.
Not even the tone control topology show any resemblance to TS circuits. So the design here is not like many the others. I wonder what would have happened if DOD had decided to paint these green. Since majority of players at the prime of this unit’s selling days were about to slam it as a TS-derivative anyway, the green colour would have been a nice touch. Then some folks would have possibly noticed that the TS and Classic Tube do not sound alike.
The build quality is common with all the others from this era of FX-series units and the electronic switching follows others too. And if we try to find a continuity in the design presented in the schematic, this might very well be the link between FX50-B Overdrive and FX55 Super/Supra Distortion. After all, it is brighter in red (could it be called more yellowish?) than the Super/Supra – so in a sense, also a missing colour between the FX50 and FX55. You could also check out the notes on Americas Pedal on the FX53. I believe the author in there is right about the unit trying to be a competitor to TS9, not to copy it in any way.
Even if there were similarities in the tone to the “suspected sisters”, the design does not support that claim. And again, no. Neither does the sound.
How does it sound?
There is a certain emphasis on the mid frequencies that may have led some people to think TS. To me, however, words like amp-like and smooth come to mind. Neither of these are words that i would use to describe a TS or its derivatives. The amount of gain available is quite different too.
Now i’m starting to piss myself off. Why on earth do i keep comparing this to TS, when it has clearly very little to do with that design? Because most of the world still do call FX53 a “DOD’s take on a Tubescreamer”. The design, nor the sound, have very, very little to do with it. How can i be more clear about this? Please. Stop referring to TS when you talk about this effect. I know i’m going to stop doing it. Right. Now.
Hi, I found your website by g00gling “dod classic tube fx53 mod”.
Excellent article you’ve written, well done. I have owned my own fx53 since purchasing it used for $50 CAD back in the mid 90’s. I used it a few times, was generally unimpressed by its capabilities and stuck it in “the drawer”. Now I’m examining it again to see if it might be useful in some way in my current rig. Any thoughts on the possibilities of modding this pedal to upgrade the components to a more modern build? Thanks for the post!
Hi.
I personally don’t think there’s anything wrong with the components. At least in the sense that swapping them for “better” ones would yield noticeable differences. To mod one of these.. Well. There’s already quite nice amount of gain, but there would be a bit room for more, if the 680R resistor between distortion pot and 1µ cap was lowered to something in the lines of 220-470 ohm.
To tweak the output level, one could play around with the value of a resistor between IC2’s pins 6 and 7. Higher value there would increase the volume. So the 18K could be upped for 47K-56K and see if that makes it soar. One could maybe even go higher..
The clippers are maybe the single biggest change one could do. These diodes make up the distortion texture, so those play a big part. There are two standard silicon diodes shunt to ground after C4. Doubling those for four of 1N4148 (louder, less distorted), or swapping them for schottkys (1N4001 for example, for crunchier texture) or LEDs (even more crunchier) would definitely be worth a try.
FIS site and the schematic seem to be down, but here’s another version of the schem: https://1.bp.blogspot.com/-IIbjFfkbn-M/T-_GMa22QHI/AAAAAAAABaI/P6GKHkpDvbU/s1600/DOD%2BFX53.gif
Otherwise the frequency response (at least in my opinion) is quite good. So – gain, volume and clipping texture.. Those three may be worth to try moding.
+m
Mr Mirosol!.
Hey thanks for the reply!
Made my day. My eyesight has detiorated to the point where I can longer reliably solder or do macro work so I’m going to take your suggestions and present the to Greg at SolidGoldFX. They do mods occasionally and several years ago Greg did a bang up mod on an old TS 10 that I sent him. He even retained the midrange hump, in fact he even accentuated it for a kind of cocked way tone. I love it. Now I’m going to find out if he can perform the same kind of mojo on my FX53. Unless YOU would like to take a crack at it ???? I’m in no rush and am prepared to pay the going rate. Interested?
This is actually super interesting! I’ve been way too busy with my dayjob for past six months, so i’ve been behind on comments (as well as tons of other things). Some cool mod would be nice thing to do. I notice you’re in canada.. Shipping to here (finland) and back would probably be the biggest concern.
In case you might still be interested and you’ll see this, drop a line to mirosol at kapsi dot com.
+m
I’m in Crete… I’m interested in more gain and losing some of that woofy low end (that’s common in fuzz boxes)…