Friday, 18 April 2014

ValveWizard Equinox II

Request, and also for those who want another PT2399 based reverb pedal.  Not one for the faint hearted with that many links and cuts! :o)

One thing you will notice straight away is that this doesn't have the usual 3PDT stomp switching to bypass the effect.  Because it has tails, the stomp will just turn the effect (and LED) off and not mechanically bypass the circuit, so in bypassed mode IC1 will just act as a buffer.  So the input and output wires go straight to the sockets, and only a SPDT stomp is required.

With this being a dual PT2399 build I don't think anyone will want to run it off a battery because if they do it really won't last very long, so this should fit fairly comfortably in a 1590B without making allowances for battery space, and especially with a single pot.

Info from Merlin about his project:

Equinox II: Reverb with Tails
This project came about because I wanted to roll my own reverb. A common way to do this is to use a tapped delay line, but no such chips exist any more. No matter; the result is the same as using multiple delay lines in series and/or parallel. Several DIY reverb effects use the excellent accutronics Belton Digi-Log reverb module, and the associated patent, US8204240, shows that it uses three PT2399 delay chips, one of which is modulated at a slow rate to give a more realistic spring reverb sound. The Accutronics module is not commonly avalable in Britain (also it's cheating to use a ready made effect module!), but I did have a tube full of PT2399s (I absolutely love these chips). I also wondered whether just two could do the job, and it turns out that for guitar use you can indeed get a primitive but usable effect this way. I think this makes the Equinox II the simplest DIY reverb project on the net at the moment!

In the Equinox II the reverb effect is acheived by passing the audio through two delay lines in parallel. One is arranged for a short delay (about 80ms), and the other a long delay (about 250ms). The outputs from each are summed and fed back to the input of the delay lines, and also mixed with the original audio via a mix pot- that's it. (I have an affection for one-knob effects.)

In detail, after passing through the input buffer the guitar signal is sent both to the output mixer and to the JFET analog switch. This switch allows the input to the delay line to be muted, creating bypass with tails (this is exactly the same as my Small Time delay).
Following the JFET the signal then passes through a 15nF capacitor which provides a little bass cut, to stop the reverb getting too muddy, and it then feeds into a second-order high-cut filter. This is also where the output of the delays lines is fed back in.
The output of this filter feeds the short delay line, and also the long delay line (via an unavoidable inverting buffer).
After the signals emerge from the two delay lines they are both summed and filtered again. All this filtering is necessary to reduce noise from the analog-digital-analog conversion inside the ICs.

I spent a long time tweaking the delay times, filtering, feedback, and mixing ratios, to get what I think is the most usable reverb sound using standard component values and the simplest architecture. My first Equinox prototype also had adjustable delay time on the long delay line, and a fat/bright switch. But I didn't find these to be very useful (at anything but the optimum delay time all you get are 'metallic bathroom' type sounds), so I trimmed the circuit down to the bare essentials, creating the Equinox II shown here.


To see more information including the schematic and a PCB for those who want an easier life, check out Merlin's page here, and a clip can be heard here which sounds pretty damn good to me!





And after discussions below, a version which omits the JFET and instead uses the second pole of the stomp to turn the reverb on and off.  This will also keep tails intact as per the original but because of the parts omitted has removed a link and a couple of cuts and is one column smaller.



66 comments:

  1. I noticed a mistake in the first layout I posted, so if you want to build this, download the latest version now posted above

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    1. j112 can be replaced with j201?
      whether the 14k7 resistor can be exchanged with 15k?
      thnx before...

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    2. Yes J201 should be ok, which 14K7?

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    3. sory I mean, 17k2 resistor can be replaced with a 20k resistor?

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    4. Series. Yep, a 15k + 2k2 wired series should be fine.

      I used an 18k, myself.

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    5. He actually showed a 15K and 2K2 in series in the schematic, but I made it a 17K2 because I noticed I had some in that value.

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    6. 17k2 resistor is hard to find in my town. Where layout with version 1 or version 2? what do you think? I want to make this reverb. and I want a cool reverb: D thanx

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    7. Just use an 18K or a 15K + 2K2 if you prefer. The effect will be the same with both builds, so just choose which type of switching you want. The JFET should be silent, you may get some noise with a mechanical switch which will make the decision for some people.

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    8. without the use of JFET whether the sound will be the same, thank before, whether this would be a good layout with SPDT / DPDT toogle switch?

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  2. PT2399...
    J112...
    78L05...
    another PT2399...

    What fresh hell is this!??!

    From the corpse of Little Angel Chorus hall arise (hopefully) er.. THIS LAYOUT!

    So yeah, at least I definitely have the parts for this now :D (needed 1 J112 for the Little Nightmare Chorus, bought 20... hell yeah.)

    I'm going in...

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    1. Good thing I just stocked up on some big-ass pieces of Vero board. I can smell the phenolic aroma already...

      http://dl.dropboxusercontent.com/u/3078710/vero.jpg

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    2. [to the music of Ferris Bueller's Day Off]
      Ooooohhh yeahhhh
      chicka chickahhhhh

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  3. Ha ha, that's the other great thing about DIY, recycling failures :o)
    For God's sake don't build the first one I posted, it won't work. Hee hee

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  4. Oh and I bought 20 too, dpi4parts are great :o)

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  5. Alrighty. I've built it. It's a nice, if limited, reverb. I'll admit,I kind of didn't want to put my guitar down yet to type this, but it's 00:30 here and I have to be up at 05:00 for work :/

    I can't call it verified yet, though, because the switch only seems to turn the LED on and off. The reverb effect is on regardless of the switch.

    Now, I found out I did not have a dpdt or spdt stompers in stock (just momentaries) so I used a spdt toggle for testing. I don't see that making a difference for testing, though.

    So either it's 100% good and I have a switch error somewhere (I'll check closer tomorrow.. er.. later today) or it's nearly 100% (the effect itself good!) but with a switch error on the layout (probably not, but I'm going cross-eyed following the buffered effect flow).

    At any rate I had a lot more success with this layout, so far, than I did with the Little Chorus of Broken Dreams, so my pedal building palette has at least been cleansed a bit.

    My over all opinion of the effect is that I would definitely build one of the Belton brick reverbs first ( I built a Ghost Echo myself and look forward to building a Wampler Faux Spring somewhere down the road). They are NOT to be without. After that, this is a very good sounding reverb and at least $20 cheaper in parts... not to mention, that Belton module can be hard for some people to source.

    Recommended as long as we can figure out the switching (which, again, is probably something specific to my build..) it will help when someone else gives this a try to compare notes.

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  6. Made a quick sample of what it sounds like. It's late and the strings on this guitar are still stretching a little bit. so don't judge me, heh ;)

    Guitar ( The "Blue Special" http://dl.dropboxusercontent.com/u/3078710/0007.jpg ) bridge and middle pickups --> ValveWizard Equinox II (knob all the way up) --> Bugera v22 tube amp. No other effects.

    https://soundcloud.com/heathhouston/ts

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    1. Excellent, so it seems to be working. We just need to see what's happening with that JFET

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    2. I was pretty sleepy when I posted that, so it didn't cross my mind to just replace the J112! Thinking back, the one I used was one of those I pulled back out of the Chorus Who Shall Not Be Named project, so it's possible I was using a damaged transistor.

      That's going to be the first thing I try when I escape from today's indentured servitude.

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    3. Is the JFET connected correctly on the layout? On the schematic on ValveWizards "Schematic, layouts and BOM" document the Source is connected to the output of the first stage of TL072 and the Drain is connected to R9 (10k) wheras on the layout it is the otherway around.

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    4. I didn't look in the PDF, I just used the schematic when doing the layout, so I'll correct that, thanks for the heads up. It won't matter to the operation though, drain and source are interchangeable with the J112 (and most other JFETs).

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  7. OMG thank you!
    I will build this as soon as I'm home.
    Thank you!

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  8. Aha! Finally reverb project with PT2399 :)), this one must be done this week. many thanks Mark

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  9. This would make a great add-on to another circuit in a 1590BB box (like a Tremolo, ala Mr. Black Deluxe Plus) where you don't want to add a bunch of knobs.

    I think I might combine this with the Valvecaster Tremolo and a switch to change the effect order. Could be deeelliiiciiioouuuussssss....

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  10. One thing that may be worth considering though (especially if you haven't got any) :o) is doing away with the JFET entirely. I don't know about anyone else, but I don't have any SPDT stomps anyway and so I'd use a DPDT or maybe even a 3PDT and just use a single pole. But if like me you're using at least a DPDT then you can simplify it and use the currently unused pole to disconnect the feed to the PT2399s mechanically.

    With your stomp switch lugs like this:

    1---4
    2---5
    3---6

    Just omit the JFET and the Stomp 3 wire (you could also omit the diode, 1M resistor and 10n cap to ground if you want), and then connect Stomp 4 and 5 to the free holes to the right hand side of where the drain and source connected. That will make the connection and illuminate the LED simultaneously, and when the connection is broken you will still get tails in exactly the same way.

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    1. I've included an alternate layout above just in case anyone wants to try this method. It saves a few components and is one column smaller.

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    2. Thats extremely impressive Mark. Reworking the original layout and doing a separate variant for manual switching so quickly. Since I had only started picking the components and had not started on the vero I think I will go for the jfetless version.
      (Especially since I dont have a J112!)

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  11. I have built the jfetless Equinox II and it works so that layout can be verified. The effect is just like the Valve wizard demo. However, with this version there is a noticeable "pitter-patter" when you press the button to turn the reverb on and anyone who wants to turn the effect on in the middle of a performance would probably find that unacceptable. It doesn't bother me as reverb is something I either leave on most of the time or not depending on the environment.

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    1. Yes that was my only reservation about mechanically switching it on and off, but figured the same could be said with any mechanical switching in a circuit like diodes, input caps etc, so sometimes you may get a bit of noise, with other builds it would be silent. But it works that's the main thing :o) Thanks for verifying matey.

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  12. Has anyone gotten the second layout to work? I'm not getting any bypass signal but do get the pitter patter when switching on and off.

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    1. Norwichbadger did. What voltages are you getting?

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  13. Hey IvIark, did you happen to make any changes to the first layout AFTER the corrections posted on the 18th? I built the first layout last weekend and am just getting around to troubleshooting it now, and the right side of the board looks like things have been rearranged.

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    1. Possibly John. If I see something about a layout I don't like, or see an improvement or space save that I can make then I do it and replace the layout. But they are always functionally identical unless I note an error I spotted and corrected, so if you have a previous version saved then it will be fine to use. I think the version that Heath posted the clip for was the second version so there was only one correction to this which was almost immediately after posting.

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    2. Yeah, unfortunately I didn't save a local copy and didn't print. I'm just going over my build trying to spot if I placed something incorrectly. Guess I'll skip that step and go straight to probing.

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    3. This is annoying. Usually I save every previous revision when I modify a layout but I can't find this one. If I find it I'll post a link

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  14. I'm building this at the moment. I'm probably a little dense, but what (physical) sized caps are people using for the 4 that run down the right side of IC2? 4 MTK caps don't fit unless you turn the 3rd one 90 degrees to the others. The lead spacing on everything I have takes 3 vero holes..

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    1. I'd use small multilayer ceramics personally. I sometimes (like with the Deep Blue Delay) put the top two caps one column to the right which allows you to use poly box caps with one of the legs bent back to a 2.5mm pitch and use the space above and below to accommodate them, but I think those little multilayer ceramics are excellent and so have no problem using them rather than polyester, especially at times like this when space is at a premium.

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    2. Thanks for the heads up on the small ceramics, didn't even know they existed really. Didn't think to use the column to the right either. Might do that too.

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    3. Bah. I've finished it and got nothing. The LED doesn't even light up - I've built the jfetless one. No bypass sound, no effected sound. My battery was getting hot though, so I'm going to assume something is in backwards and go from there.

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    4. Well without any voltages it's only a guess, but if the battery isn't 100% then it may not work even if the build is perfect. Two PT2399s draw a lot of current and if the battery is low you may not get 5v from the regulator. So more info needed

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    5. willy you can post your voltages here if you want,so i can compare them with mine which works perfect and it's still out of a box, and if i can find something wrong, i would be happy to help. but first of all i think you should use a wall dc adapter as mark said..and check your voltage reg too...

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    6. Thanks guys, I'll post my results asap.

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    7. Well, this is annoying.
      - Fresh battery reading 9v.
      - Found the (old recycled) battery clip was dead, replaced that with a fresh one.
      - Ok, battery reads 9v off the clip.
      - hook up clip to circuit - no volts. Not even between 9v and ground on the vero...
      - Remove battery clip and leads from vero - measures 9v
      - Hook clip back up to vero - 0v

      Something is very messed up here. As soon as I wire up the battery, I get nothing. I can't even get a reading between the battery terminals if I push the leads into the clip...

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    8. I'm pretty sure you have a short on your board. That would eplain the symptoms.
      +m

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    9. I should be able to read something off the battery though shouldn't I, like where the 9v and ground meet the board!

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  15. build this yesterday! it worked at once and it worked perfect!fantastic pedal Mark! but i think that the reverb range is too short.i've tried 50k and i think i'll go with 100k...or is there another way to do this?

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  16. ah!!and has anyone else saw the same problem? and how did you solve it? cause i would like a bit more "fat", "rich" reverb

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  17. Hi,
    It is possible to change the 15nF capacitor by a 22NF?

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  18. hello there. i've build it some weeks ago, but i have a problem with this.it's the only buffered effect i have and it destroys everything...so i never use this. when it's in chain with all my pedals, it kills all tones. it's like it sucks everything and spits it back though a barrel...the effect works, but i need to find a solution on that cause i really need a reverb...
    is it the tl072?
    what should i do?
    just live with it?

    any ideas??

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    Replies
    1. ideas anyone???does all buffer bypassed pedals act like that?

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    2. I built this for a friend and I painstakingly tested it with a bunch of my home-mades. It's my only non true bypass build so I was concerned.

      I've had no problems and neither has my friend. Unfortunately I don't have it here to compare, but I can tell you that Merlin is a pretty talented EE... might be worth posting on one of the forums dude.

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    3. Thanks Tom. If you're having problem with the bypass, why don't you simplify it and true bypass it. You won't get tails but then not many people need them with a reverb pedal which is likely to be always on at your preferred setting. Just build the JFETless version, make a link from Stomp 4 to Stomp 5 and then true bypass the input and output wires. The Stomp 1 and 2 connections can still be used for the LED pole.

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    4. I should be thinking you for the awesome layout! worked perfectly first time. I must say, I'm thinking of building another since it's always a good idea to have at least one buffer in the signal chain.

      By the way I've built many of your layouts here and only recently did it occur to me to write here. Another addict! Thanks you guys for all your efforts. Some great stuff here, you make a lot of people very happy!

      Tom

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  19. I also had great luck with this one, worked first try. Which never happens. I ended up taking it back out and socketing the 17k2 and 4k7 on the left side to tweak the delay times to my preference. Ended up using 21k7 and 5k6 for a bit more spacious reverb, but definitely got a variety of interesting and useable results while experimenting.

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  20. hi,
    just fin this build and worked first time here too. :) thanks for all the info and the work here.
    any one else tried diff resistor values as jeremy above..?
    was going to try pots there to have it tweak able into odd sounds..any ill effect on the circuit by doing that..apart from loosing the sweet spot its in now?
    or a larger main reverb pot .. does it increase the range?
    thanks much
    hitech

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    1. Oh and yeah it does "pitter-patter" when the effect is switched on ...and i built the Jfet Ver. not a problem for me but i wonder why that would be happening. my main rev pot is A20K ..could that be it ? coz its only audible towards the higher end...

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  21. This comment has been removed by the author.

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  22. hey, i don't have 1u ceramic cap. can i use electrolitic instead and if so, how sgould the polarity be?

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  23. Hello,
    Finished the 1st version circuit and double checked it. Instead of spdt I used a 3pdt footswitch I had in stock. I only used the 3 pins(1 column) of the switch. The led pops up fine but I get no sound and no bypass. What should I do? Also is there any way to do true bypass on this circuit. I noticed that the footswitch doesn't connect to the input output jack. Please help , I am soooo close.

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  24. I build the second version JFETLess but i have problem.... i feel work only the tl072 and i listen all time in standar tempo a sound like switch on off on off on off..... can help me anyone please?

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  25. AGH!! Futurlec/Tayda here I come....A brickless reverb? Opinion seeking: judgement of this vs. Brick based verb please?? I've built all types EXCEPT reverb. Never bought a brick. Is this better?

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    1. Better is subjective word. This takes just 2 PT2399s, while those belton/accutronics bricks have three in them. This is more subtle reverb, representing a small room and limited reverb length/decay.

      In that sense the brick is better. But brick is around $15-20€, while two PT2399s cost pennies. In this sense Equinox 2 is way better.

      If you're still at zero reverb builds, i'd suggest you build both :) Why not take them in to single 1590BB, wire Equinox first and brick circuit sencond. Then just add JFET-Marshall-in-a-box with them and you'll have a JCM900 Dual Reverb in a pedal :P
      +m

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  26. hey there,
    i'm having a little trouble on this one.
    i built the jfetless version with tails and put it into an eddystone 1590b enclosure (somehow it worked ;-). so far so good...led lights up, bypass signal is flowing and not harming the tone in any noticable way. so i assume the buffer is working.
    now the problem...no effect!!! when turning on the effect (led lights up) there's no change in tone at all. i guess that the sgignal is not passing the 2399's in any way. i will do a volt check on the ics as soon as i have time and post them here.
    do you guys have any suggestions where else to look? i checked all the parts, links, cuts and wiring and couldn't find any mistakes so far.
    here (http://i117.photobucket.com/albums/o63/notasmine/IMG_3433.jpg) is a pic of the finished board so maybe you could have look at the parts i used. cause of the someitmes very little spaces for rather bigger caps i used alternatives. maybe i've choosen wrong ones, even i think a cap is cap and as long as the value is right (or close) it still should work.
    anyways, it'd be great if you could let me know if you can think of any problem i could have.
    cheers, martin

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    1. me again...
      after checking all the parts again and changing the 100n tantalum caps to regular ceramic caps (since i found out that they have a mounting direction) i still got the problem mentioned above.
      i also tried to audio probe the circuit with the result of ending up after the 15n cap having half or not even that much of the sound left. resoldered the cap, exchanged it...with no positive result.
      i looked up the voltages on the ic's...as following
      tl072
      1 - 4,72v
      2 - 4,72v
      3 - 2,3v
      4 - 0,0v
      5 - 4,5v
      6 - 4,72v
      7 - 4,72v
      8 - 9,45v

      lower pt2399
      1 - 4,99v
      2 - 0,0v
      3 - 0,0v
      4 - 0,0v
      5 - 0,0v
      6 - 0,0v
      7 - 0,0v
      8 - 0,0v
      9 - 0,35v
      10 - 0,35v
      11 - 0,38v
      12 - 0,38v
      13 - 0,32v
      14 - 0,32v
      15 - 0,32v
      16 - 0,32v

      upper pt2399
      1 - 4,99v
      2 - 2,48v
      3 - 0,0v
      4 - 0,0v
      5 - 3,36v
      6 - 2,48v
      7 - 0,53v
      8 - 0,66v
      9 - 1,09v
      10 - 1,09v
      11 - 1,09v
      12 - 1,09v
      13 - 1,09v
      14 - 1,09v
      15 - 1,09v
      16 - 1,09v
      can you read any problem on that?
      i'm really a little lost and don't know where else to look and what parts to check.

      i noticed, that when i took the voltage measurements while having the effect plugged in the amp and a pop came up, the pop was repeated on pin 1 of the lower pt2399. so i guess somehow something is working...mh
      it'd be great if any of you guys has a hint what part to check on.
      thanks in advance, martin

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  27. me again...
    the problem above was due to a broken pt2399 (upper one). after replacing it with a new one it worked just fine.
    now it just stopped working again after the main power of our practice room went out.
    checked all other divices including board power (from gigrig) with no negativ results.
    because of the solution from the last time i just changed the upper pt2399 again. well and it worked again. but now it has some kind of issue with working steady. it sometimes gets quiet all the way, then only a bit and then comes back to full life.
    somehow shaking seemed to help ;-)...so i checked all the connections and wiring finding no mistakes. it must have something to do with the circuit or better to say the parts.

    do have any suggestions where to look?
    thanks

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