Phase Revolution - Perf & PCB layout for R.G.'s Phase 180 Plus

[frequencycentral]

All done!

[John Lyons]

Great work Rick!
The board looks very nice. Cleanl
Curious to hear how it sounds.

john

[frequencycentral]

Thanks John, the board took quite a bit of planning. My favourite part is how the board is secured inside the enclosure (and grounded/powered) using solid core to the in/out sockets and the DC socket. I dislike having boards loose inside enclosures, so this was a good solution for me. I'll be doing it that way again.

As for how it sounds, I've never owned or built a Phase 90 to compare it to, though last month I built a Phase 45 to which I added two extra stages. The P180 is definately a thicker phase, though I'm not finding it as 'intrusive' as say a Small Stone with the color switch on, or my old Boss PH2 in mode II, which may be a good thing as the phasing it offers is musical without being over the top. I'm also not entirely convinced of the value of the extra pots really, I need to play with it a lot more though to discover all the possibilities, but there seems to be a sweet spot for each. But I'm on a phaser quest, so it was worth building. Still searching for the ultimate swooshy phaser, next up will be an eight stage Ross with the Hammer mods. I tend to use some of my pedals for gigging/rehearsal, some set up in my home guitar rig, and some set up with my Rhodes 73 MkI, so I have no problem in duplicating pedals!

[Slade]

Didn't you get some phase oscillation noise when you're not playing or volume loss with the 8 stages version?

I made this (not uising your layout, but one I made) and it works but I have that 2 problems.

I'm using NE5532's for the LFO and I used different cap values for the first two and last two stages and the 4 stages between them in this order: 33n/33n - 47n/47n/47n/47n - 33n/33n.

I made this 8 stages selectables with a toggle switch, so you can have 4 or 8 stages.

I can hear the oscillation of the paser when I'm not playing... 

[frequencycentral]

I don't have any volume loss - maybe you need to look at the output transistor and its associated resistors. Not sure what you mean by phase oscillation noise, but yes I can still hear it quietly doing it's thing when I'm not playing.

I have different issues. My vref is 4.1 volts, so the central point of the bias pot is a little off from where I'd like it to be. I'm going to see if I can get the vref down to ~3 volts, which should solve the problem, though I suspect it's linked to the Vgs of the FETs I'm using.

The Regen/Feedback control doesn't seem to do anything at all, I'm going to try feeding it back at different stages to see if I can get it to do anything. The only post I can find about a Phase 180 build also states that this pot doesn't do anything.

Also I used a 100K Mix/Blend pot, though the schematic states 200K. I don't think it should make any difference, but it doesn't work in quite the same way as the similar pot on my JC Mailett modded Phase 45.

It does sound great though!

[Slade]

Thakns for your inspiration  Now I know what's is causing the volume drop..
Yes, with phase oscillation noise I was saying that I can still hear the pedal doing his work when I'm not playing.
Well, my regen pot is woking fine, I'm "feedbacking" to the second stage, not the first, with a 27K resistor and a 50k pot. I didn't use the mix pot, instead of it I use the Width (or depth) pot, like I said before in this thread, and it works great.

Regards.

[GP]

Rick,

I had a go at building your (spin-off) layout for the Phase 90 and I've had quite a nightmare trying to get it to work. After some hours of checking and double checking I'm pretty sure I see a mistake in your layout.

According to the schematic, the output of each opamp should connect directly to the 47n cap for the input of the next stage and not through a 10K resistor as you've done with your layout. That said, I'm sort of baffled as to how you've got your Phase 180 working because you have exactly the same layout "mistake"... if I'm right that this is a mistake, that is.

[doitle]

I am in disbelief as to the that perfboarding... How did you make it so perfect? You should make a video tutorial or something so we can all try to be 1/10th as good! At least I'd love to see a video like that. I probably couldn't perfboard an SHO booster circuit. :/ Well actually I tried and failed at perfboarding a rangemaster and that's a pretty darn simple circuit.

[doc_drop]

You should make a video tutorial or something so we can all try to be 1/10th as good! At least I'd love to see a video like that.

+ a gazillion.

[frequencycentral]

Rick,

I had a go at building your (spin-off) layout for the Phase 90 and I've had quite a nightmare trying to get it to work. After some hours of checking and double checking I'm pretty sure I see a mistake in your layout.

According to the schematic, the output of each opamp should connect directly to the 47n cap for the input of the next stage and not through a 10K resistor as you've done with your layout. That said, I'm sort of baffled as to how you've got your Phase 180 working because you have exactly the same layout "mistake"... if I'm right that this is a mistake, that is.

Damn, you are correct. I've ballsed it up. Mine does phase, though I have a problem which I assumed was to do with the FET biasing, but you've just pointed out that I've made an error with the layout. Oops, and sorry. Having said that, it should be pretty easy to correct. Thank you for pointing it out, I'll correct my build and update the layouts over the weekend. 

[frequencycentral]

I am in disbelief as to the that perfboarding... How did you make it so perfect? You should make a video tutorial or something so we can all try to be 1/10th as good! At least I'd love to see a video like that. I probably couldn't perfboard an SHO booster circuit. :/ Well actually I tried and failed at perfboarding a rangemaster and that's a pretty darn simple circuit.

Thanks - but I still make dumb mistakes! Oh well. Perfect perfing? Use a pointy fine tipped soldering iron, use thin solder and be frugal with it, follow a good layout (hah!), take your time. A video tutorial? Well maybe I could do that sometime, let me think about it. It's actually very flatteing to be asked for one!

[GP]

Well, i'm even more baffled then because that (very very beautiful) soldered perfboard picture you posted looked just like your layout. As an aside, your regen return is injected into the wrong place too! I noticed you'd posted that it didn't seem to do anything on your build - this might be why!

As per the Phase 90 layout you posted, mine wasn't phasing but behaving like a tremolo - are you sure yours IS phasing and not just having more of a pronounced effect than mine because of more stages?

Anyway, I made some adjustments to mine to fix the problem. It's not as easy as one would like because i had to route some wires under the board because your layout is so tight. It's working better but it's still not working as a phaser so maybe i've missed something else. Everytime I connect in the regen, it squeals like a pig so I still need to work on it.

[frequencycentral]

As an aside, your regen return is injected into the wrong place too! I noticed you'd posted that it didn't seem to do anything on your build - this might be why!

Yeah, I'd noticed that and corrected it to the right place already, still no control over regen though, which is obviously to do with the mistake (x8) you've pointed out.

.....are you sure yours IS phasing and not just having more of a pronounced effect than mine because of more stages?

Mine is phasing, but with issues as I said. Maybe you are right that the extra stages make it more pronounced with mine.

You've actually got me really stoked to get this sorted, with mine it's like there's a really good effect in there just waiting to get out. I assumed all the issues were FET biasing based, but obviously not!

As for your other issues, maybe they are FET biasing based. See this thread: http://www.diystompboxes.com/smfforum/index.php?topic=77324.0

I can't thank you enough for bringing this to my attention, now I know there's a major flaw I just can't wait to get it 100%!

I've done this layout, took a while...................I know the chances are very slight - but anyone care to check it over for any obvious errors before I start building it?

Well, where were you then? 

[GP]

where was i then? somewhere in france on my way back to the uk... no internet, no soldering iron, no help at all, i'm afraid.

I only built this because i've had some matched Jfets lying around for ages and i've just not gotten round to it. I'm currently collecting together parts to build a Tau Pipe phaser (not for guitar use) so I thought i'd get myself into the moodfor phasers while i wait. I'm normally a vero man but your layout looked lovely so i didn't even think to verify it before putting solder to board.

yes, i'm figuring the the problem is fet biasing but it's taken me long enough to realise the problem with the layout!

[frequencycentral]

where was i then? somewhere in france on my way back to the uk... no internet, no soldering iron, no help at all, i'm afraid.

Shame on you!

The Tau is a serious project - nice! I love phasers, I'm on a phaser quest myself, I've tried and failed to design a submini tube phaser, though it shouldn't be so different from the submini tube vibrato I've previously posted, so I figured I'd go phaser crazy to get me prepared for the next stab at the tube phaser. I'll do an 8 stage Ross soon too. My previous phaser build, a P45 with 2 extra stages and JC Maillet's mods went so smoothly. Ah well, we all gotta @#$% up sometimes............

[GP]

Yep... the tau is serious but i have a spare 19" rack box and it needs filling with something interesting. A 9v stompbox phaser doesn't really cut the mustard in that setting.

i'm not so worried about knocking up a tau on vero as much as trying to get hold of the parts. Not easy to find 3046s nowadays and lm394s or ssm2210s are not cheap if you've got to buy 22 of 'em.

[frequencycentral]

So I've just performed the surgery required to correct my layout @#$% up. Wow! The 'really good effect in there just waiting to get out' has now been unleashed! Amazing, a very deep and chewy phaser. The Regen control and the Blend control have now totally come to life. The Regen self oscillates when it's maxed out, so I'm going to add a larger value resistor to set the maximum a little lower. The surgery wasn't fun, entailing making 7 little 'bridges' from one point to another. I'm not sure if it's going to be easy to amend the layout to take in the corrections without adding slightly to the board size. I'll have a crack at it anyway.

The corrections I made are within the areas inside the black circles, entailing cutting a jumper and inserting a short red wire in each case, except for one that just required a jumper to be moved. If you compare it to my original layout you'll get the picture. The Regen connection has now been moved to the correct location.



Thanks again to GP for pointing this out and helping me make this build work the way it should.

[1878]

Any chance of some samples ?? I was gonna build a plain old phase 45, but I think I'm about to change my mind 

Also, do all 8 FET's have to be matched ?? I can get hold of matched FET's in batches of 4, not 8.

[frequencycentral]

I'll try to get around to soundclips over the weekend. I also need to revise the PCB slightly in light of my errors. 

Yes you do really need all eight FETs to be matched. The set I used have a Vgs of -1.8 volts. I'm still in the dark as to the optimal Vgs for FETs in Phase 90 and derivatives, though my instinct tell me that maybe -1 volt to -1.5 volts would be good.

I used LM324 quad opamps because I have loads, TL084 (for example) have the same pinout and should would just fine too.

[R.G.]

At the risk of impeding an in-progress party, ( ) I've had good luck retrofitting the phase 45 style JFET gate-drain feedback circuit into P90 phasers.  It cuts the JFET distortion a lot, making it sound much smoother.