Wednesday, 11 July 2018

Ethos TWE-1

Info:
"Inspired by the Trainwreck Express amplifier (built by the late Ken Fischer), the TWE-1 is solid-state pedal designed to emulate the touch-responsiveness and clean-to-overdriven range you get from a high-grade tube amp. Along with Volume, Hi Cut, and Gain controls, the pedal has 3-position Cab switch (4x12, 2x12, off), a Presence switch that provides three levels of high-frequency boost (post OD), a Voice switch (Traditional and Modern British), and a bypassable Brite switch that provides two levels of high-frequency boost (pre OD).
The TWE-1 with its Gain at noon or higher responded in an amp-like way to changes in guitar volume and picking strength, delivering everything from gritty cleans to richly saturated distortion textures. Thanks to its strong output, the TWE-1 is suitable for clean boosting too. All good stuff, but the standout feature of the TWE-1 is its powerful tone-shaping ability. The Hi-Cut knob attenuates treble when turned clockwise, and the Brite switch makes it easy to get the appropriate sparkle with humbuckers or single-coils. The Cab switch beefs up the low-end significantly in the 4x12 position (I felt the 2x12 setting sounded best with my Deluxe), and the Voice switch lets you choose between a thicker tone in the “M” position or one with more upper-midrange emphasis in the “T” setting. The Presence switch set to Hi restores shimmer when the Hi Cut control is turned up (a cool sound in itself), and between all of these functions, the TWE-1 certainly answers the needs of players who want a compact OD pedal with exceptional sound and flexibility."
The layout should fit in a 125B size box.
You can find Bugg's schematic and easier-to-build pcb on his website here.
This is a buffered effect. Follow the layout to connect the footswitch.



47 comments:

  1. Check out Brett Kingmans video of this also. Killer!!! Im working on Pedalpcb's board now.

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  2. Really cool indeed, Alex. I was almost about to request this one from you hehe! I just need to find where to get those 1v8 zeners...

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    1. It could be the 1N4678 diode: 1.8v zener diode. Pretty rare, indeed. I think someone of us should find some replacement.

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    2. why not just take 3 1N4148 in serial. They forward around 0,6 V each.

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    3. Three 1N4148 or a LED, a green diffused one, I guess it's ok. In any case we should get about 1.8v forward voltage.

      I just concern about a little detail in case we have to use a LED. I found this note about it on wikipedia:
      https://en.wikipedia.org/wiki/LED_circuit
      "but voltage drop normally rises as the light frequency increases".

      Maybe this is the reason why MAO suggested to reverse the orientation.

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    4. Bit late. But in europe you could always send an e-mail to the guys of new-tone
      team@newtone-online.nl
      They don't have the specific zener. But they can usually source a lot of components.
      Website is only in Dutch. But they don't shy away from sending international

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  3. Looking at the schematic, I think LEDs with a 1.8v forward voltage reading would accomplish the same thing. I'd probably reverse their direction though.

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    1. When you say "reverse" did you mean connect the anode of the LED+diode combo to the cathode of the PCB?

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    2. I would disregard the LED & Diode combo, they had no effect on the sound. In fact, I can't hear and difference with the 1.8v zeners installed or not.

      Also couldn't "see" any effect when viewing with a scope. Really dont understand their pupose here.

      My theory is the 1n4148s clip the signal below the 1.8v reverse voltage of the zeners, so they never "turn on", but they may clip a square wave in the 0.7v direction But again, I couldnt hear or "see" a difference with the zeners installed or nothing installed.

      So, try it without anything 1st, then if you have a slightly higher voltage zener, try those, and then try some 1n4148s.

      Let us know if you can hear any difference.

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    3. Actually I tried swapping their orientation and, I agree, they don't seem to contribute anything to the sound. I wouldn't be surprised to know the same effect even without. Thanks!

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  4. https://www.mouser.com/ProductDetail/Central-Semiconductor/1N4678-BK?qs=sGAEpiMZZMtQ8nqTKtFS%2fNTW9pm8IdF6NwWdEkMc7Gx7JO0zV3Ng4Q%3d%3d

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  5. I did a search and I think it's not possible to get those 1N4678 zener here in europe. Mouser has a website even in german and a contact in munich, but there are about 20 Euros for shipping ...

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  6. Nice blog about the guitar FX. If you need custom picks please let me know. www.custompicks.com

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  7. Replies
    1. That was a mistake. Changed this instead of the GTC Bloody Finger.

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  8. Hey Alex, what is your idea about this zener diode?

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  9. The reverse voltage drop of the zener is 1.8V but the forward drop is 0.7V like a normal diode. Therefore the drop across the back-to-back zeners is around 2.5V in both directions. However, low-voltage zeners such as these have a soft knee, i.e. they don't turn on abruptly. This should have a soft clipping effect, probably why they were chosen.

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  10. I have built this pedal using this layout and it works very well.
    I tested 3.3V zener instead of 1.8V and there is not much different of how the pedal sounds.

    Thanks Alex for a good work!

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    1. Cool! Thank you for verifying it!

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    2. Thanks!
      In case I'll build this pedal the lowest zener I could find is 2.7v from Musikding.

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  11. These look ok for the 2.2 uf MLCCs?

    https://www.mouser.com/ProductDetail/810-FG18X5R1E225KRT6

    Thanks

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  12. Yes those capacitors will work fine.
    For anyone having trouble to find the 1.8 zener diodes an alternative is to buy the smd version.It's not difficult to solder each one across two rows of a small vero board in the space between two holes.Then use two pieces of wire to create a homemade through hole diode.

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    1. Thanks Dimitris. Appreciate the confirmation. There were several versions of the same thing - I read the data sheets but just wanted to make sure I was in the ballpark.

      I also got my 1.8 zeners from Mouser.

      https://www.mouser.com/ProductDetail/Central-Semiconductor/1N4678-BK?qs=sGAEpiMZZMtQ8nqTKtFS%2fNTW9pm8IdF6NwWdEkMc7Gx7JO0zV3Ng4Q%3d%3d

      Thanks again!

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    2. This comment has been removed by the author.

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    3. And of course, thank you Alex for the excellent layout!

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  13. Hi Alex! Sorry for disturbing here, but I haven't found any contacts on the site. I would like to thank you for sharing the awesome 4ms Swash layout, that was my first ever DIY project, and I was succesful. I would like to ask You something, is there a way to talk privately?

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    1. Hi Zorius. No problems. The emails are available in the Forum section. Mine is alexcannonball@hotmail.com

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  14. Finished mine up last week, after a quick listen was surprised at how good it sounded with all the controls flat.

    IMO, most of the professional youtube videos make just about any pedal sound great...this one really does sound great!

    After a couple nights of play, this is one versatile high-gain pedal, with multiple settings sounding awesome, rather than just one or two settings.

    Had thought before actually building this, I would probably eliminate a switch or 2 and hard wire my favorite settings, but after listening to it live, I'm going to keep all four. Don't even think I'm going to tweak anything.

    No doubt this one will be replacing my Sovereign Distortion.

    Highly recommended!

    Note regarding zeners:
    For now, I subbed a yellow LED in series with a 1n4148 for each of the zeners. I hope the money I spent on the 1.8v zeners will be worth it, 'cause it sounds pretty great right now.

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    1. Thanks for the tip on the zener subs, MAO.

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    2. I would like some explanation about this replacement.
      How a yellow LED and a 1N4148 have to do with this famous 1.8v?

      Thanks!

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  15. See EddieB's note regarding from July 20th.

    Replacing each zener with a diffused yellow LED and 1n4148 wired in series would give about 2.4v drop in each direction, very close to the 2.5v mentioned by EddieB.

    However, EddieB also mentioned the turn on time of these zeners is slower, whether or not this difference will be audible remains to be heard.

    The LEDs never light up, so it will be interesting to hear the difference, if there is one.

    I plan to report back my findings after my zeners arrive. (end August)

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    Replies
    1. Thank you MAO, and I thank EddieB, I have underestimated his note.
      Mao, I'm waiting your next report about the zener.

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  16. Ok, the 1.8v zeners came in.

    As EddieB stated, they measure 1.88V in one direction, and 0.7v in the other.

    Results:
    I cannot hear a difference at any gain setting between the zeners and the led+diode combo I had subbed in (described above).

    In fact, I hear no difference with them completely removed from the circuit!

    I measured the voltage where the zeners connect to the circuit (Vref and 220R,D3,D6)

    Vref = 4.5v
    220R,D3,D6 junction = 4.4V

    So about equal DC voltage on either side of the zeners.

    I don't have a scope to check out the AC waveform.

    But I'm thinking given an AC waveform greater than +/- 2.5vs, the zeners would create a square wave with +/- 2.5v peaks prior to passing through the 1n4148s.

    And if that is true, then either the AC waveform isn't greater than 2.5v and the zeners are doing nothing, or my ears aren't sensitive enough to detect their influence.

    I just can't hear any audible difference with them in or out of the circuit. (Pedal still sounds awesome to me regardless)

    Hoping someone in the know can better explain the zeners purpose here.

    Until then, I would say save your money and hold off on purchasing the zeners.

    Request: Maybe someone else who has built this can lift one side of the zeners to see if they can hear a difference?

    Thanks
    Mike

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    1. Built this last night without zeners, worked just fine. I´m gonna try to tame the gain a bit to see if it fits my sound better. It´s to higain for me.

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    2. Hey Leif,
      I'd start by swapping out the 1M and 220p that are in parallel with a 470k and 470p.
      And change the gain pot to a 10k audio taper.
      There should still be plenty of gain on tap, but this should tame the lower gain settings a bit.

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  17. Mike - to check the audio signal I use soundcard and Visual Analyser software, plus very simple "probe" (https://www.build-electronic-circuits.com/wp-content/uploads/2014/08/sound-card-oscilloscope-probe-schematics.png). With VA you can have two channel oscilloscope.
    T.

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    1. Thanks molu!

      Took about 15 mins to put the LM7805 probe together (found in comments section of the site you referenced)

      https://www.facebook.com/SoundCardOscilloscopeProbes

      I'll post some details in the forums, but at this point I'm unable to detect an audible or visual change with the zeners connected per the schematic.

      Scope pics:
      http://guitar-fx-layouts.42897.x6.nabble.com/Ethos-TWE-1-1-8v-Zeners-tp43628.html

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  18. Can I run 2x 1uF MLCC's in parallel in replacement of the 2u2 MLCC's?

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    1. I think you can.
      For the lower 2.2uF in the board the upper legs of the caps have two free holes, for the bottom legs you could junction those together, or create a free hole moving to right the upper leg of that 1M resistor, so you can solder the two 1uF caps slightly oblique.

      For the 2.2uF in the first stripe you have a free space for a second caps, just be careful to how much space take those two caps.

      The 2.2uF close to the D1 is a bit complicated. I guess you just joint the legs and to use the only two holes.

      With two 1uF, of course, you will get 2uF and not 2.2uF. I don't know how much difference it will do in the sound. I advice to looking for the 2.2uF.

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    2. Thanks. How about running this on 1n914 instead of 4148?

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    3. I think those diodes are interchangeable, but I'm sure you can find the 1N4148s without problem.
      I try always to follow the original layout. Maybe you could socket the diodes, and later solder the 1N4148s. Or the 1N914s if you like them.

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  19. I just finished building it and plugged it in my test box
    I built it without the zener diodes and with TL072 instead of 2134
    Everything is working fine but I have a few remarks I'd like to share:
    - I have a huge volume boost between the 3 positions of the cab switch
    - Same with the Hi position of the presence switch
    - Bright switch is pretty subtle
    Are you guys experiencing the same ?
    Is it worth purchasing 2 2134 to replace the TL072 ?
    Thanks

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    1. Mine responds exactly as you described, and I believe that is by design so you are good there.

      The 2134s may have an effect on the touch sensitivity and possibly on the edge of breakup, but that's just a guess.

      If you can hold off for a week or so, I am planning to build another one and will try it with TL072s. I can then AB the two and see if there is a difference between the 2134s and TLs. (was planning on doing this regardless)

      Those zeners are still a mystery to me. And the diodes look like some kind of crossover distortion arrangement, again kind of unique as I haven't spotted that setup in another pedal.

      Whatever the case, I love the sound and responsiveness of this pedal. We will have to see how much influence the 2134s have, the zeners appear to have none.

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    2. Thanks for your answer !
      I will try playing with caps values for the brite switch
      Also, I think the gain pot tap is a bit off, it's kinda on/off thing. I'll try the mod suggested before in the comments, maybe with a log taper pot.
      The bass response is a bit flubby, not very tight, but also may be from playing at low volume on a 10" speaker.
      I'll be interested in your feedback with opamps, thanks !

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  20. Did anyone try plugging this straight to PA?

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    1. I have not but I did replace the preamp of a little practice amp with it.

      The power amp and speaker are very dark in this amp, but the TWE was able to adjust for it with the cab, presense and hi cut controls.

      It was a bit loud, so I had to lower the gain of the power amp, but sounds great.

      I'm thinking it will work well direct. Most likely with completely different settings than feeding an amp.

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