Modding the EAR AD4096 MkII Analog Delay (Endangered Audio Research)

[pwu]

Those who own or who have played with this pedal know it sounds great. There are a few things we'd all like to see changed that bother us, so here is where those mods will be collated and tested, by us.

I'm looking for some help with the mods I'm trying to achieve. Hopefully any successes listed here will help others find the courage to achieve their goals and tinker away without fear.

This list is followed by a short comment of what I'm trying to achieve, then any values linked to this area that may be a good place to start.

1️⃣ Add Delay Tone knob (integrated with another knob, maybe Mix, as a concentric pot).
I'd like to be able to modify the existing lowpass filter so the overall delay can be a bit brighter or darker.
Filter Switch connects directly to: R47 (100k), R49 (100k), C48 (1μF), & C58 (10μF).

💫★ SOLVED! Make Modulation Depth less extreme.
Added a resistor between the third leg of the Depth pot to the board. 18k worked, but the pot needs to be Logarithmic/Audio taper, and all 6 pots are 10k Linear. I have a 100KA pot which works fine, but the resistor needed be increased in value to 39k. MUCH more usable range of the pot dial and at the extreme end.

3️⃣ Add better power filtering to remove hum.
I'm getting a low level hum from most power supplies, including my Walrus Phoenix. The only one I have that is completely silent is the Fulltone FPS-1.
Power supply negative tip connects directly to: D1 (1007), R13 (10 ohms), C2 (0.1 μF), C5 (1000μF), C8 (10μF), Q2 (L78L33) 3.3v regulator, dsPIC33FJ64GP802 (micro controller), & Bypass Switch.

4️⃣ Fix noisy power jack.
Mine makes a static noise whenever a power plug moves or turns in the jack. Solder joints are fine. Any ideas? Does yours do this too?

5️⃣ Fix or remove the buffer.
There are two issues I have with the always-on buffer in this pedal:
One: Your guitar's input tone is ALWAYS slightly duller when plugged into this pedal, on or bypassed, as previously noted by @Tabor and @Skinbonedaddy here: https://www.thegearpage.net/board/index.php?threads/endangered-audio-ad4096-mk2-who-has-theirs-and-what-do-you-think.1757293/page-16
Two: When Bypassed, in "Trails" mode, and using a boost into the AD4096, newly played notes can be heard making new delays, but they are "farty" and obviously unwanted. This is not good.
Output connects directly to C24 (1μF) & R26 (100k).
Input connects directly to R5 (10k), then to C1 (100pF) & C4 (47nF).

💫★ SOLVED! Dim the indicator light more when bypassed (or turn it off).
Removed R72 (18k). Light is now off when bypassed.

Any help is truly appreciated, especially from the man Todd Kelley himself.
I never get a reply through his website. Anyone else had luck? I asked about the Trails issue twice, but no reply.

1️⃣ and 5️⃣ are the items I need the most help with, followed by 3️⃣.

I absolutely love this pedal, and am willing to mod it. Who's in?

[pwu]

[Ice-9]

4️⃣ Fix noisy power jack.
Mine makes a static noise whenever a power plug moves or turns in the jack. Solder joints are fine. Any ideas? Does your do this too?

6️⃣ Dim the light more when bypassed (or turn it off).
I'd like the light to be barely there or off when bypassed. This should be easy.
(I think) R67 (10k) parallel with R69 (10k) is pedal ON (5k total). R69 alone is for Bypass.

2️⃣, 4️⃣, and 6️⃣ I can handle on my own and will be posting all progress.

4. Turning the psu jack causes static noise is most likely a power connection between jack and socket, ie tarnished or loose contact or even centre pin size slightly different to jack hole size, replacement of socket with a quality one should fix this.

6. If the circuit is as you describe then remove R69 for no LED in bypass and adjust R67 for the LED intensity when on.

You already said you can sort these two ideas yourself but that is all I can suggest, especially without a schematic for the rest of the pedal.

[pwu]

4️⃣ Noisy power jack: I noticed my Bogner 'La Grange' does the same thing, so maybe it's inherent to certain circuit designs that are more sensitive to power.

[Mark Hammer]

I've encountered more than a couple of instances where a 2.1mm plug and jack do not consistently make a good connection.

A buffer should theoretically result in a brighter, rather than duller, tone.  That is, after all what a buffer is designed to do, or at least is normally designed to do.  Is there any sort of mismatch between the loads you are feeding it and its input impedance?

I generally deal with the tone of the delay signal using 3-position toggles, since they only require changing the value of parts already in place, without requiring any sort of major revision to the design.  There will always be a cap in series with the wet signal on its way to the mixing stage, and a cap in series with the feedback path, on the way back to the feedback-return node.  A toggle can be used to select between stock and smaller values, to cut the bass.  There will also usually be a fixed resistor in series with each of those caps.  I like to split each into two common values that add up to the original, or slightly smaller, and run a cap to ground from their junction, to roll off treble.  So if there is a 12k resistor, for instance, one would split it up into 10k and 1k8, or maybe 6k8 and 5k1.  One then does the math and selects the cap value/s that result in useful rolloffs.

Note that each of these provides a shallow (6db/oct) rolloff, and that doing such mods in the feedback path tries to achieve progressive cuts, while similar rolloffs in the overall delay path are fixed.

[pwu]

★ SOLVED! Add Delay Tone knob.
R55 (10k) controls how much treble gets passed into each repeat! The higher the value, the brighter the repeat. I've found success adding just 10k, but I'm ordering a 50k linear concentric pot to integrate with the "Repeats" knob, since it also affects the repeats.
The change sounds wonderful! I love the extra harmonics I'm hearing. Maybe this is the "Sonics" knob that was not implemented.

Videos and photos will follow shortly.

[pwu]

★ Add Delay Tone knob.
I've actually achieved this in an unexpected way: via changing the "Voice" pot.
I simply disconnected the pot, joined the circuit where lugs 2 and 3 were, and replaced R55 (10k) with a 50kA pot. Now, the middle of the pot is the previous "Voice" sound at max, and it gets a little brighter from there.

★ Dim the indicator light more when bypassed (or turn it off).
Remove R72 (18k) = Light is off when bypassed.
Replace R72 with 33k = Light is noticeably dimmer when in bypass

Unless I can figure out the signal loading issue, I will probably use a relay bypass to alleviate the anxiety I have with the integrated buffered bypass.
Probably this one: http://smallbear-electronics.mybigcommerce.com/relay-bypass-module-kit-mv-57b/