Earthquaker Devices - Disaster Transport JR

skywise · Post by **skywise** » 26 Nov 2012, 16:34

http://www.earthquakerdevices.com/devic ... portjr.htm

Nice build quality inside. Nothing new to see here but a picture is nice anyway.

batteryacidtea · Post by **batteryacidtea** » 29 Nov 2012, 21:40

Nice! How do you like it? I'm really interested in understanding how does the tone control works here!

bugg · Post by **bugg** » 15 Dec 2017, 20:27

PCBs available here: http://www.pedalpcb.com/product/cataclysm/

marshmellow · Post by **marshmellow** » 16 Dec 2017, 00:50

Ever since the Rebote every PT2399 Delay has to suffer from this nonsensical input stage design. Everybody just copies it again and again without wasting a single thought

.

jrfox92 · Post by **jrfox92** » 16 Dec 2017, 08:59

marshmellow wrote:Ever since the Rebote every PT2399 Delay has to suffer from this nonsensical input stage design. Everybody just copies it again and again without wasting a single thought .

What's nonsensical about it?
Do you just have a problem with input buffers?
The only difference between the Rebote and the data sheet (from what I remember) is a Jfet boost at the input.

marshmellow · Post by **marshmellow** » 16 Dec 2017, 13:20

That's not a buffer, that's a noise generator with a NF in excess of 20dB. For a unity gain stage that is just ridiculous (and copied blindly by Mad Professor, Wampler, several Madbean designs, many DIY variations, ...). An inverting stage as a high-impedance input is simply wrong. You either have low impedance, or high noise, choose your poison. The way to go is to use a non-inverting buffer and don't care about the polarity inversion. Which is a bit schizophrenic in the first place considering that 99% of other effects don't care a single bit about this issue. Or you put a JFET/BJT buffer in front of it and decrease the resistors to 10k.

Or you build something that was properly designed from the beginning, like the PT80, the original PT2399 design, or Dirk's contest entry.

phatt · Post by **phatt** » 16 Dec 2017, 13:38

marshmellow wrote:That's not a buffer, that's a noise generator with a NF in excess of 20dB. For a unity gain stage that is just ridiculous (and copied blindly by Mad Professor, Wampler, several Madbean designs, many DIY variations, ...). An inverting stage as a high-impedance input is simply wrong. You either have low impedance, or high noise, choose your poison. The way to go is to use a non-inverting buffer and don't care about the polarity inversion. Which is a bit schizophrenic in the first place considering that 99% of other effects don't care a single bit about this issue. Or you put a JFET/BJT buffer in front of it and decrease the resistors to 10k.

Or you build something that was properly designed from the beginning, like the PT80, the original PT2399 design, or Dirk's contest entry.

Take Marshamellow's advice,, print that out in RED Bold and refer to it everytime you build a pedal.
You don't need noise gates and other crap if you build them properly,,, jezz the front end of a TS9 with BJT would out perform in a noise shoot out.
Noise is the hidden enemy in pedal design and easy to get caught as it's not obvious to the novice.
Phil.

snk · Post by **snk** » 21 Jan 2019, 22:49

Hello
I built and EQD Disaster Transport JR and i like it.
I also started studying other PT2399 designs, and found the Hamlet Delay, where (among other things) it is suggested to put a green LED from PT2399 pin7 to ground in order to avoid clipping the PT2399 input.
Did anyone try it on the Disaster Transport JR ? Would it work the same way ?

snk · Post by **snk** » 24 Jan 2019, 20:16

Also, what do the antiparallel diodes to ground do, in the EQD - Disaster Transport JR ?
(Maybe it is a crude limiter for the feedback ?)

Post by **audioguy** » 19 Nov 2019, 17:08

What might turn out to be a silly question-
How difficult would it be to add a toggle switch to kill the primary signal, allowing only the delayed signal to pass through?

Optical · Post by **Optical** » 19 Nov 2019, 20:50

For wet only, disconnect R9

bc108 · Post by **bc108** » 15 Jun 2021, 13:21

I'm thinking in build this one into a small veroboard, and add before some Echoplex Preamp.
Is this one more "lo-fi" compared to Deep Blue, or Wampler Faux?

jeepe · Post by **jeepe** » 25 Jan 2022, 17:20

hi,
at tagboardeffectlayouts, Servant07 had spotted an error in the "pedalpcb schematic"...
in this thread: https://tagboardeffects.blogspot.com/20 ... rt-jr.html

Servant07 3 January 2018 at 07:11

Finished troubleshooting on paper, didn't have time to make the changes to my build tonight, but I think I got it with shifting a few parts around. The main things are that R12(47K at IC2 pin 15) on the PedalPCB schematic is missing, and the 10uF above IC2 should go from pin 5 of IC1 to ground (right now its connected to ground on both ends).

(Only the bold part of the message refers to the schematic)

PS:
he also uploaded a vero layout link:

Servant07 4 January 2018 at 05:06

Got it working tonight. Unfortunately I had to add an extra column for the missing resistor at column 17. Here is a link to the new 23 column wide layout: https://www.dropbox.com/s/lgvctnhdtqyfmpw/DTJ.png?dl=0

Earthquaker Devices - Disaster Transport JR [traced]