Most famous mods with the V2.0 extra space

  • Thank you for this post, bsas.
    I'm almost finished building my Yocto2 (just waiting for a couple more components to arrive) and I'd love to add some mods as well, once I've been able to verify everything works as it should.

    I think it's particularly strange that none of the mods have been documented yet, as clearly a lot of work has been put into adding extra holes for pots and switches.
    I honestly don't really see the need for a new Cocteau board > there's enough space foreseen on the Yocto2 PCB in order to directly add your own mods.

    I recently found this really informative post, but unfortunately the used pot values aren't documented. Maybe it can be of use for you:
    http://jacobkorn.de/news/roland-tr-808-modrepair.html
  • Here is my current ideas after some research:

    BD:
    POT1) - Endless/Extended Decay -- replaced R170 (470k) with 380k resistor in series with a 100k(B) potentiometer
    POT2) - Tuning -- replaced R165 (47k) with 100k(A) potentiometer (audio/log preferably)

    SD:
    POT1) - Noise – R201 is replaced by 25k Pot and 1k in series
    POT2) - Tune for lower oscillator - 1M(A) Potentiometer with 220k in series for R198 (1M)

    LT:
    POT1) - Noise = R216 - 15K to 5K + 50K(B) pot to reduce the amount of noise
    POT2) - Reverb = R232 - 1k + 100K(B)

    MD:
    POT1) - Noise = R245 - 15K to 5K + 50K(B) pot to reduce the amount of noise
    POT2) - Reverb = R261 - 1k + 100K(B)

    HT:
    POT1) - Noise = R273 - 15K to 5K + 50K(B) pot to reduce the amount of noise
    POT2) - Reverb = R288 - 1k + 100K(B)

    RS:
    POT1) - Tuning -- changing R316 (1M) with 220k resistor in series with 1M(A) pot (??? R312 ???)

    CB: (replace trim pots) TM1* and TM2*
    POT1) - 220k(B) pot
    POT2) - 220k(B) pot

    OH:
    POT1) - Filter -- replaced R147* (2.7k) with a 10k(B) potentiometer in series with a 1k resistor

    CH:
    POT1) - Filter -- replaced R153* (2.7k) with a 10k(B) potentiometer in series with a 1k resistor
    POT2) ? R61* replace 10K with 4k7 + 10K(B)
    SWT1) ? C67* between TO_HH (original) or WN (R130 to C56 or C127)
    SWT2) ? C71* between TO_HH (original) or WN (R130 to C56 or C127)
  • I have a Cocteau modded Yocto and can comment from my experience.

    BD extended decay doesn't sound good IMO, I would prefer Env Amount.

    What is SD Noise ? What is very nice for SD is Snappy Decay and Snappy (hipass) Filter. But the shape of the original decay is very relevant in the 808 sound and here when I enable the mod even if I can get a value resulting in about the same decay time, it doesn't sound the same.

    Also SD Tune for lower osc is more about getting more bass in the sound than really tuning. For more tuning like the higher osc would be more relevant in my opinion. Also note that those osc mods use shielded cables.

    What are the 3 last mods for OH ?

    Also let me check about the pots taper because I guess that many people documented mods with not the best one.
  • I am about to finish building my Yocto 2 as well. I would love to compare notes for the mods with everyone here. I'm happy to see some action in this forum!
  • gihaume wrote:I have a Cocteau modded Yocto and can comment from my experience.

    BD extended decay doesn't sound good IMO, I would prefer Env Amount.

    What is SD Noise ? What is very nice for SD is Snappy Decay and Snappy (hipass) Filter. But the shape of the original decay is very relevant in the 808 sound and here when I enable the mod even if I can get a value resulting in about the same decay time, it doesn't sound the same.

    Also SD Tune for lower osc is more about getting more bass in the sound than really tuning. For more tuning like the higher osc would be more relevant in my opinion. Also note that those osc mods use shielded cables.

    What are the 3 last mods for OH ?

    Also let me check about the pots taper because I guess that many people documented mods with not the best one.
    Thanks so much gihaume!!!

    So, let comment on each of your points:

    BD:
    - For the longest time I wasn't sure between "BD Decay" and "BD Env" and I found almost zero examples of how it sounds. So, I will definitely take your suggestion by hearth and I will do the "BD Env" instead of the decay. Thanks!!!

    SD:
    - "SD Noise" is a mod I found in the forum that just "filters" the SD noise. In the Cocteau it is called "SD Filter". Sorry for the confusion :(
    - "SD Decay" changes the circuit adding a resistor (a pot) in series with the C51 capacitor. Since I don't have switches to disable the mods, I rather not do any mod that change the circuit too much. I am looking to do all mods just replacing resistors with resistor+pots or just pots because then I can "mark" in my case where the pot is exactly the value of the original resistor and consider that position as "stock".
    - I was also not sure about "SD Tune" on low OSC or high OSC. Again, no examples online of the sound difference, so, I will take your suggestion too and do the "SD Tune 1" (at R197) instead of the "SD Tune 2" / "SD Low OSC" at R198. Thanks again!!!
    - Yep, shielded cables is a must :D

    OH/CH:
    - So, I couldn't find too much info on good OH/CH mods that interested me. So, what I did was a mix of suggestions:
    -- POT2) That mod is called "Metal Tune" in the Cocteau and I think it changes a lot of stuff (not just OH/CH).
    -- SWT1 and SWT2 are the noise source for the OH/CH. In the circuit diagram it gets is noise source from "TO_HH" part of the noise generation, but, I though about those switches to "change" the noise source to WN. The other option (that I am thinking more about it) is to have one switch to "collect" WN/PN from the noise generation circuit, and the other switch to change the noise source on "both" OH/CH between "TO_HH" and the "WN/PN" option. Not sure here.

    RS:
    - Since you have a Cocteau can you please tell me which one is the best here? What I am doing is the "RS Tune 1" but I wasn't sure between this and the "RS Tune 2" (you can see my interrogation marks over the R312). Again, thanks a lot!!!
  • Here are a few exclusive CY/CH/OH mods.

    https://www.muffwiggler.com/forum/viewt ... 77#2699277

    Metal Tune affects the tuning of both CB oscillators at the same time. Those are also used in the CY, OH and CH sound.
  • gihaume wrote:Here are a few exclusive CY/CH/OH mods.

    https://www.muffwiggler.com/forum/viewt ... 77#2699277

    Metal Tune affects the tuning of both CB oscillators at the same time. Those are also used in the CY, OH and CH sound.
    Hi gihaume, thanks again! I am reading all the mods you listed there and having a lot of ideas.
    So, since you have the Cocteau unit, can I ask you some stuff?

    1) RS: which one of the mods do you think are more useful? "RS Tune 1", "RS Filter" or "RS Tune 2"?
    2) Do you like the "Metal Tune" mod?
    3) Do you like the "OH Filter Resonance" (R146) and the "CH Filter Resonance" (R155) mods? They look quite similar to the filters I am pointing in my list but I am not sure which resistor makes the most difference in the circuit.

    Thanks!
  • 1) RS Filter is very nice for shaping the sound. Originally it was going too low which wasn't useful. RS Tune 2 also affects the CL so it may be interesting.
    2) Metal Tune is very nice because you shift both CB oscillators at the same time so it's easier to detune then recover. Also if you don't use the CB, it's a nice way to easily change the CY/OH/CH's sound.
    3) OH/CH Filter Resonance are awesome. They are close in the circuit from the Filter (Cutoff) mods but obviously don't do the same thing. They are not famous because they were just found but now I have them I wouldn't ever live without.

    For the pots taper, just read this post and if you think the mod is the same one and you was planning to use another pot taper, just change or be careful (do not solder its big legs).

    Feeding the CY/OH/CH with Noise instead of Schmidt trigger sounds very nice, but it's worth mentioning that CY/OH/CH Metal Drive when drived the most sounds very similar so could almost be interchanged. But in the case where you use Metal Tune to shift the CB pitch pretty high, the CY/OH/CH sounds become more "pitched" (and Metal Drive here sounds more like a bit reducer) and feeding Noise could be useful.
  • gihaume wrote:1) RS Filter is very nice for shaping the sound. Originally it was going too low which wasn't useful. RS Tune 2 also affects the CL so it may be interesting.
    2) Metal Tune is very nice because you shift both CB oscillators at the same time so it's easier to detune then recover. Also if you don't use the CB, it's a nice way to easily change the CY/OH/CH's sound.
    3) OH/CH Filter Resonance are awesome. They are close in the circuit from the Filter (Cutoff) mods but obviously don't do the same thing. They are not famous because they were just found but now I have them I wouldn't ever live without.

    For the pots taper, just read this post and if you think the mod is the same one and you was planning to use another pot taper, just change or be careful (do not solder its big legs).

    Feeding the CY/OH/CH with Noise instead of Schmidt trigger sounds very nice, but it's worth mentioning that CY/OH/CH Metal Drive when drived the most sounds very similar so could almost be interchanged. But in the case where you use Metal Tune to shift the CB pitch pretty high, the CY/OH/CH sounds become more "pitched" (and Metal Drive here sounds more like a bit reducer) and feeding Noise could be useful.
    Again, gihaume, you are the best, thanks so much!
    So, here is my current mod ideas:

    ---

    BD:
    POT1) - Tuning Envelope -- replaced R166 (6.8k) with a 10k(C) pot in series with a 390R resistor
    POT2) - Tuning -- replaced R165 (47k) with 100k(C) pot in series with a 1k resistor

    SD:
    POT1) - SD Filter –- replaced R201 (22k) with a 25k(B) pot in series with a 1k resistor
    POT2) - SD Tune 1 -- replaced R197 (820k) with a 2M(B) pot in series with a 470k resistor

    LT:
    POT1) - Noise -- replaced R216 (15k) with a 50k(B) pot in series with a 5k resistor
    POT2) - Reverb -- replaced R232 (100k) with a 100k(B) pot in series with a 1k resistor (connect pin 1 to ground)

    MD:
    POT1) - Noise -- replaced R245 (15k) with a 50k(B) potentiometer in series with a 5k resistor
    POT2) - Reverb -- replaced R261 (100k) with a 100k(B) pot in series with a 1k resistor (connect pin 1 to ground)

    HT:
    POT1) - Noise -- replaced R273 (15k) with a 50k(B) potentiometer in series with a 5k resistor
    POT2) - Reverb -- replaced R288 (100k) with a 100k(B) pot in series with a 1k resistor (connect pin 1 to ground)

    CB: (replace trim pots)
    POT1) - TM1* -- 250k(B) pot in series with a 100R resistor
    POT2) - TM2* -- 250k(B) pot in series with a 100R resistor

    RS:
    POT1) - RS Filter -- replaced R322 (10k) with a C10K(B) potentiometer in series with a 1k resistor

    OH:
    POT1) - Filter Resonance -- replaced R146* (68k) with a 250k(B) potentiometer in series with a 1k resistor

    CH:
    POT1) - Filter Resonance -- replaced R155* (68k) with a 250k(B) potentiometer in series with a 1k resistor
    POT2) - Metal Tune -- replaced R61* (10k) with a 10k(B) potentiometer in series with a 4k7 resistor
    SWT1) - Switch between metal and noise (OH and CH) -- One pin to "TO_HH" from Cymbal and a another from SWT2 (switch goes on the legs of both C71* and C67*)
    SWT2) - Switch noise between WN and PN -- Grab those from the noise source. Probably U24B pin 6 or 7 for PN and U24A pin 1 for WN.

    ---

    Also, I have this crazy idea that I will NOT build the "NOISE" section of the PCB. Instead, I will make an third board with the same exact circuit and connect to the main board using JST connectors. The benefit is that, in the external board, I will plug two 3.5MM STEREO jacks (one for WN and one for PN). So, with that, if I want I can "replace" the circuits WN or PN with some external source... What do you think?

    Thanks!