For them's who's interested:
I haven't found a DIY version of this legendary phaser, and always wanted one, so here's my shot at it. This is a condensed/modified version of the original board, put together from various gutshots; still bigger than I would like (right around 5" wide), but a smaller layout is a project for another day. I'm using the GGG bipolar power supply for this- tried an LT1054 doubler/inverter but this puppy apparently draws more than the ~50mA or so that that circuit supplies. Still playing with conversion to a single supply.
So far, it sounds pretty good, but bear in mind that I don't have an original to compare it to. The ramping feature on this phaser is pretty sweet. IMO, it would benefit from adding foot-controllable speed and doing away with the three switches, but I haven't had time to play with it yet. Should be easy to implement, though. In fact, it looks like the board could fit (snugly!) into a wah shell...
Tranny numbers are listed...I initially tried matched 2N5952 FETs but couldn't get 'em happening; the 5485s seem to work well. They were matched using the Greatly Improved FET matcher here: http://tagboardeffects.blogspot.com/2012/07/greatly-improved-jfet-matcher.html (http://tagboardeffects.blogspot.com/2012/07/greatly-improved-jfet-matcher.html) There may be better subs for the original 2N4303 FETs and the 2N3638A bipolars, but these seem to work well, though socketing is a good idea. I'll try to get a BOM up soon.
One other thing: the 10uF polarized cap in the middle of the layout isn't on the schem and was only present on one board, but I threw it in anyway. Probably not necessary.
Anyway, enough yakkin'.
Schematic:
(http://i1220.photobucket.com/albums/dd454/jdub5248/PS1-A_zpsa91ac74b.gif)
Layout:
(http://i1220.photobucket.com/albums/dd454/jdub5248/MaestroPS-1Alayout_zpsd63d6d14.png)
Transfer:
(http://i1220.photobucket.com/albums/dd454/jdub5248/MaestroPS-1Atransfer_zps5163fafe.png)
Enjoy!
I posted a thread about one of these a while back. The one I messed with was built into an SG Systems amplifier and was an absolute blast to play with. Been wanting one ever since. Glad to see someone else taking interest in this pedal, it's a true classic that I think deserves more love than it gets.
Couldn't agree more...it's got a beautiful swirl/throb thing going on that I haven't heard in many phasers, almost Vibe-like.
Awesome! Nice work.
nice add and vintage style tracing.
Excellent! I had one for years and still have a couple SG's with them in. Besides the great phasing, the switches are unique. Forget a speed control. The slow and fast speeds are set at the two speeds of a Leslie and ramp up and down when switching between the two. You won't match that ramping with a pedal. THAT is the best feature of this pedal.
Plus, it sounds great on bass as well.
I wondered where this layout came from! Cheers dude. Just built this and it's a stormer! FWIW the 2n5087 on the input is backwards on the layout. As are all 6 of the 2n5485s. The HA17458 opamps we got from Tayda work, which is good as other things we tried didn't. It's worth adding the 5 RF surpressing caps underneath the board also as it's good at getting radio with out them.
As the board needs +/-12V. We've used a 12V supply with LT1054 on Madbean's Road Rage for -12V. Hopefully it will work with Madbean's new dual charge pump circuit at 9V when it lands as we found trying to do it with a single didn't yield as good results as a 12V source.
(http://juansolo.demon.co.uk/stompage/images/ps1a-o.jpg)
(http://juansolo.demon.co.uk/stompage/images/ps1a-i.jpg)
Nice work, man! Looks and sounds excellent. Sorry about the backwards trannies, once again I uploaded the wrong version of the layout- I have about 10 revisions of it saved and used the wrong one. Correct one is now in my layout gallery (http://www.aronnelson.com/gallery/main.php/v/jdub/Maestro+PS-1A+layout.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/Maestro+PS-1A+layout.png.html)) or here: http://i1220.photobucket.com/albums/dd454/jdub5248/MaestroPS-1Alayout_zpsaeda6660.png (http://i1220.photobucket.com/albums/dd454/jdub5248/MaestroPS-1Alayout_zpsaeda6660.png).
I love this phaser, it's my favorite so far. If I may ask, how did you wire your stomp switches? Did you go true bypass? I'm about to rehouse mine- my prototype just has spst switches and no LEDs, and I'm trying to decide how I want to do the stomps.
I had to use the 47pF RF blocking caps, too- the radio stations were louder than the effect at times. I also had to do some LFO deticking- used a TL062 as well as some surgery to install a 100R resistor to the +12 pin and a 22uF to ground.
I bet it would work well on +9/-9V, but I already have it set for +12/-12 from an AC adapter, so I'll just stick with that, I guess.
Cheers, man! Glad you like it! ;D
I tried it at +9/-9V and the lack of headroom in comparison to +12/-12V was surprising. I wouldn't recommend it. Indeed I've thought about going +15/-15V like the Oberheim.
It's wired true bypass. The slow and common are linked so it's always on, and the in/out just go to the optical switch board (could just as easily be a 3PDT). The only downside is there is a little bit of a volume drop when you engage the effect.
No issues with ticking on this one.
But yeah, it's a stunning phaser. The speeds are nigh on perfect, the ramping effect is cool as hell and it just sounds damned good. Well worth a build and many, many thanks for doing the project!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!! ! ! !!! ! :icon_mrgreen:
sweet swirly madness love it . Good work
I hate to newb out on you, but are those DPSTs or DPDTs?
Also, if that BOM is hangin' around? That'd be pretty cool. I can make one, too, if not.
Thanks!
Quote from: yearofrolling on December 20, 2013, 10:59:31 PM
I hate to newb out on you, but are those DPSTs or DPDTs?
Also, if that BOM is hangin' around? That'd be pretty cool. I can make one, too, if not.
Thanks!
You've got the new layout which lists all values right on it.
Not much need for a BOM at that point.
Dan
Just finished my Maestro breadboard using the original parts. Sounds great!!
It is working perfectly but there might be something slightly wrong with mine because I had to remove the 10K resistor going from the FET BIAS trimpot to -12V rail to increase GATE voltage and get the FETs to modulate nicely.
With the 10K resistor I could only get -2.6V max on the FETs Gate which was not enough to get phasing. Can somebody measure their GATE voltages? There is either a small mistake on my breadboard or my FETs have a very high Vgs.
(http://i.imgur.com/Ofe52xd.jpg?3)
Here is a BOM sans the PSU:
https://mega.co.nz/#!ksokXRID!C213mSAKWfWWMXkVyuIy7y-gevld-6ygnZVrvsoT5LY (https://mega.co.nz/#!ksokXRID!C213mSAKWfWWMXkVyuIy7y-gevld-6ygnZVrvsoT5LY)
Thanks jdub for the PCB layout, will be using it soon!
with the 10k fitted, you should be getting from -6V to 0V at the pot wiper. with no 10k, you should be getting -12V - 0V at the wiper. you can put the 10k to 0V and the pot to -12V, in which case you'll get -6V to -12V, if your fets are a bit high Vgs wise.
Thanks, I'll check my voltages.
I am a bit put off by the amount of hi-frecuency loss. Didn't expect this amount.
Adding true-bypass only made this loss more apparent.
Any ideas on how to reduce the hi-frecuency attenuation?
check all your 50pF caps really are only 50pF. I don't think there should be much high attn, perhaps there is another error lurking. you'd want one of the experts to clarify what or where.
+1 on checking the 50pF caps, if you added them. I notice on your BOM that you have those caps listed as 0.47pF; are you sure you didn't accidentally use 0.47uF? 'Cuz that would sure cut a lot of high end ;)...Apart from that, I'm not sure what to check other than maybe the input cap. I don't really have much high-end loss at all with mine.
No, they are 47pF, sadly.
I put 47pf in the BOM because 50pF seems hard to find I think? ???
There must be something wrong with my breadboard. I'll check.
If I dont find anything I'll go for the PCB and hope it fixes itself!
Thanks
erm, it struck me the next day, of course. if your fet bias ain't right, it'll affect the tone. that's why I'm going with a panel mount bias on my (soon) phase 45, you can shift up and down sweepwise.
Hmm I think the bias is OK.
I think it is a impedance thing.
When I plug a guitar into the phaser and then into a DI, I get a big difference between effect-on and true-bypass.
However when I go from my sound card to the phaser and back again to the sound card (all line level) I get pretty much no difference between effect and bypass, only some volume differences.
Maybe this unit was made for line signals?
I haven't tried this in a real guitar amp yet though.
Just found out that the 4.7uF cap is backwards on jdubs layout!
Positive lead should go to ground!
This resulted in a loss of about 1.5V to the FETs gates a few minutes after powering on. This meant the phasing would become less apparent minutes after turning it on.
Reversing the cap fixed this. Now voltages are rock steady.
-----
The only problem remaining is the HF attenuation on bypass which is a bit too much for my taste.
When I wired the true bypass I would get a level drop when switched on.
How can I fix this level drop?
---
Also, I hear faint clicking. Any ideas on how to remove it?
Thanks
clikking? hmmm, that's bad. you'll need to seperate all the earth connections to the oscillator from all the earths to the audio sections. the best way to do this in my opinion, is to build the osc on a seperate board (I use vero). as for the volume drop, there is 4 resistors on the OP circuit diagram at the top right corner, marked "3k" "4k7" "12k or 10k" "3k or 4k3". what of those do you have fitted?
[edit: ] and what type opamp you using for oscillator?
Hey Tomas, sorry about the reversed cap on the layout, meant to change it as it was in my notes, but never got around to it. I need to learn to not keep so many versions of layouts...or, better yet, how to proofread :-\
I'm not sure about your volume drop, I have mine wired true bypass and don't seem to get much drop. You could opt to place a small boost circuit after the effect, I did that for an Electric Mistress I built a few years ago and it worked well.
As for the ticking, I had that problem too, though juansolo didn't. I cured mine by using a TL062 for the LFO opamp, as well as performing some surgery to install a 100R resistor to pin 8 of the opamp (the +12 pin), and a 22uF to ground from that pin. It's a tight fit, I had to cut the trace going to pin 8 and install the resistor upright, then I mounted the cap over top of the 33k. I can post a photo of the hack if you like, let me know. It totally cured the ticking.
One other thing: I posted (another) fixed layout in my gallery (orientation of the cap now correct); I also changed the MPF102 in the LFO circuit to a 2n5485. I was getting a bit of a lopsided phase, and it was tough for me to get the trim set correctly. Changing this tranny helped, TBH I'm not sure why I used an MPF in the first place. YMMV, of course...
Cheers ;)
Thanks for the info guys!
Will try the TrueBypass again now that the circuit is soldered (last time it was on breadboard). Will try a boost circuit if the problem persists.
Ticking is very faint, maybe i am being a bit anal. I might try the mod anyway. Is the TL062 important? Could I just do the 100R and 22uF to ground and be done? Dont have any TL062 around.
So its +12v rail-->100R-->pin 8 right?
I used 2N3638As and PN4303s so I think I have no problems there.
duck: I used 3K, 4.7K, 10K and 3K. Anything I should be aware of?
Thanks!
The reason for the TL062 is that it is a low-current opamp, and using such a device in an LFO circuit can help ticking by reducing the magnitude of the current spike that causes the ticking in the first place. I used a 62 because I happened to have one, but you could also try an LM358 or a TL022; if your ticking is very faint, just an opamp change might take care of it.
Correct about the other mod. You should run a 100R resistor from the +12v source (which is shared by both the LFO and audio paths) to the V+ pin of the LFO opamp, and run a 10-100uf cap to ground from that pin (22uF worked fine for me). This will decouple the LFO and the audio paths. Like I say, if you'd like a photo, let me know. If I ever revise that layout, I may add some pads specifically for that, but... :)
are you using a fet bypass circuit? I thought of the "mix resistors" on the phase 45, for inst, which are sometimes tailored for vol drop. then I got confused as to witch ones were witch, because of the extras.
Quote from: jdub on April 03, 2014, 09:24:22 AM
The reason for the TL062 is that it is a low-current opamp, and using such a device in an LFO circuit can help ticking by reducing the magnitude of the current spike that causes the ticking in the first place. I used a 62 because I happened to have one, but you could also try an LM358 or a TL022; if your ticking is very faint, just an opamp change might take care of it.
Correct about the other mod. You should run a 100R resistor from the +12v source (which is shared by both the LFO and audio paths) to the V+ pin of the LFO opamp, and run a 10-100uf cap to ground from that pin (22uF worked fine for me). This will decouple the LFO and the audio paths. Like I say, if you'd like a photo, let me know. If I ever revise that layout, I may add some pads specifically for that, but... :)
Got it! I might swap the OP amp next time I order parts. Thanks, I dont think I need a photo. Unless you want to :icon_mrgreen:
Quote from: duck_arse on April 03, 2014, 10:25:44 AM
are you using a fet bypass circuit? I thought of the "mix resistors" on the phase 45, for inst, which are sometimes tailored for vol drop. then I got confused as to witch ones were witch, because of the extras.
Yes, using the FET bypass ATM. I will go for True Bypass as soon as I have time.
Thanks!
HI,
First off, Jdub, thanks for making this thing available- this is one of the best sounding phasers ever.
I just finished my build and it seems like im in the same boat as Tomas - I have some slight volume drop with true bypass and cant seem to shake LFO ticking. Not bothered by the level drop that much, but the ticking sucks big time. I tried adding a 100 ohm resistor and cap, swapped in a lm358 and rerouted the ground (of the LFO op amp) directly to the powerjack. no luck. I guess Ill go in again and make sure the complete lfo circuit has a separate ground path, not just near the IC. Aside from that it's awesome.
One thing I can add: I have photocopied original schematics of both the PS-1 and 1a, - the later lists 5457's as a replacement for all of the 2n4302's.
edit: hmm looking back, i used a .22 uf cap in place of the .33 one by the LFO IC, that wouldnt make much of a difference, would it?
TBH, I'm not sure, but it might...I would try swapping it out for the correct value.
You know, I saw that note about the 5457s, but I didn't have enough to match a set...
What size cap did you use from the power pin of the 358?
33uf is on there now - but I also tried adding a 100uf and even threw on a .1uf for good measure. couldn't tell much of a difference.
I also swapped the other cap for the correct value.
The ticking is not so noticeable, but it is there. I can make it fade with the trimpots, but the point where it is totally gone, I have a really weak phase effect. I guess its a juggling act to find the perfect balance. The best i can get it so far, the ticks are gone when set on high, but become audible as the the phasing ramps down. Medium is the worst, on low they are so spread out that they are almost disappear.
Also maybe I should mention that before I went true bypass, I had a tough time adjusting the 'off' bias trim. Would still get a 'woosh' on the low setting even w/ the pot at max. maybe something else might be weird in mine?
Hmmm, 33uF should be plenty...have you replaced the .22 with the correct .33 yet? If the 100R resistor and cap are done correctly, plus the low-current op amp, you should be able to cure the ticking. Any other part swaps? How are you powering it?
Yeah the .22 has been replaced w/ the correct value:.33uf.
Tho' I just discovered that I used a 10 ohm resistor instead of 100-bet thatll make a difference!
edit/ nevermind- just put in a 100 ohm- still ticking.
Any chance for photos? How about the power supply?
Power supply is a regulated 12v wall adapter and an lt1054 to deliver the -12. the LT1054 is on a second board and I had the ticking before adding it. For testing/building I was using a dual regulator supply and 12v tx left over from another project.
Will try to get a pic up soon.
Got a cure for the high end loss. Strap an input buffer on to the front of it. We just used a Klon buffer and it sorts it out spot on.
So, in all we've done this to ours.
- Link the slow. This allows us to run true bypass.
- Replace the resistor on the output with a 220nF cap, then run a 1M resistor to ground after it. That gets rid of the DC and stops it popping.
- Add an input buffer. That addresses the loss of highs.
- Replaced the 2n5087 on the input with a BC559C. That addresses the volume drop.
- Add the anti-RFI caps. Because we got radio otherwise.
- Use the following power supply: http://juansolo.demon.co.uk/stompage/schematics/Power/12vBipolarPSU.jpg We get no issues with this, no ticking.
:icon_cool:
Many thanks for all your work on this, guys- you've helped make a great pedal even better!
Yep just stuck a klon buffer on the front of our two and the highs pop back. It also helps with the vol drop also. Pretty much perfect now.
why have I not built this yet?....note to self...build this!
Thanks for the updates on this Juan. I have a board ready to be populated and this info is going to help greatly so cheers. One question though, where exactly do you put the RF blocking caps? I can read the schemo easy enough and translate to layout. Thanks
I put mine on the trace side of the board, straddling the pads for the 100k resistors that run from pins 1 & 2 and 6 & 7 of the opamps. :)
I resumed the work on this pedal and housed it in a 1590DD enclosure using a 12V AC adaptor to power it up. However I am now getting noise when the effect is on.
Since this needed a buffer on the front anyway I made this "buffered-bypass" instead of true bypass. When bypassed there is no noise, perfectly clean sound.
The noise is what seems to be 100Hz hum (double the mains freq?). And its not a clean, sine 100Hz either, its kind of "sharp" noise with lots of harmonics.
I believe I didn't have this problem before the switch to enclosure/new PSU so I suspect is has something to do with the new PSU maybe?
I used this design:
(http://www.musicfromouterspace.com/analogsynth_new/WALLWARTSUPPLY/wall%20wart%20supply%20with%20load%20resistors.gif)
Any ideas??
jdub, you said you also used a AC adaptor. How is it working for you?
Thanks!!
what is the DC voltage you have at the INPUT of each regulator? it may be too low for headroom.
The input buffer in the original is not a great design (especially for guitar purposes) - we're talking this part right here:
(http://i573.photobucket.com/albums/ss171/jonnyeye/maestrops-1aoriginalbuffer.png) (http://s573.photobucket.com/user/jonnyeye/media/maestrops-1aoriginalbuffer.png.html)
From the design (DC coupled right to the output!) it's clear that the emitter is supposed to sit at 0V, but that depends on the hfe of the transistor used (the 2N3638A datasheet I found gives a "typical" hfe of 140, which gets to about 100mV off), and likely the reason the bias resistor to V- is given as 470k or 680k is to trim for least error - whatever the error is will appear at the output, potentially messing with whatever comes next in the signal chain and (if true bypassing is being used) causing switching pops. The input impedance is at most 33k, which will load a pickup significantly (loss of both volume and treble). And there is no RF rejection cap, so radio can get in.
What were the problems with this pedal again? :icon_lol:
The modern fix is to rip out the transistor buffer and replace it with an opamp buffer (Rpop is something 1M and up):
(http://i573.photobucket.com/albums/ss171/jonnyeye/maestrops-1aopampbuffer.png) (http://s573.photobucket.com/user/jonnyeye/media/maestrops-1aopampbuffer.png.html)
You may get away with leaving the output stock (with the 4.7k output resistor and no cap) with this one - the offset voltage should be small.
Or if you don't want to hack up your board too much and can get a PNP Darlington like a BC516, you can try something like this (adding the 68p cap from the base of the transistor to ground two traces over):
(http://i573.photobucket.com/albums/ss171/jonnyeye/maestrops-1adarlingtonbuffer.png) (http://s573.photobucket.com/user/jonnyeye/media/maestrops-1adarlingtonbuffer.png.html)
The input impedance is now about 400k. This one I would still change the 4.7k resistor on the output to a cap+resistor (220n+1M works) to ground.
Quote from: duck_arse on August 03, 2014, 10:29:30 AM
what is the DC voltage you have at the INPUT of each regulator? it may be too low for headroom.
Actually I am getting 17.5VDC and -17.5VDC respectively on the input of each regulator. Is this ok?
The outputs are 11.60V and -11.60V.
Great info jonnyeye! What do you think about putting a opamp buffer on the front without removing the transistor buffer? This is what I did and seems to be working correctly.
BTW any idea why my build is noisy when the effect is on?
EDIT: Started tracing the signal from the input and the noise starts creeping right at the inputs of the phasing ICs. The noise get louder on each successive opamp output. Any ideas?
EDIT2: When I dump the FETs bias voltage to 0V the noise goes away. Not too sure what to make out of this.
Thanks!
Quote from: tomas1808 on August 03, 2014, 07:45:52 PM
What do you think about putting a opamp buffer on the front without removing the transistor buffer? This is what I did and seems to be working correctly.
It works fine, but buffering a buffer offends my aesthetic sensibilities ;)
Quote from: tomas1808 on August 03, 2014, 07:45:52 PM
BTW any idea why my build is noisy when the effect is on?
EDIT: Started tracing the signal from the input and the noise starts creeping right at the inputs of the phasing ICs. The noise get louder on each successive opamp output. Any ideas?
My guess (given what other people have said in this thread) is RF interference - start by putting on the solder side of the board a 47-100pf cap from the base (centre leg) of the input transistor to ground (from the base, going towards the centre of the board, skip one trace over). If that doesn't work add the other suggested 50pf caps (47pf works fine).
Quote from: tomas1808 on August 03, 2014, 07:45:52 PM
EDIT2: When I dump the FETs bias voltage to 0V the noise goes away. Not too sure what to make out of this.
When you dump the FET bias to 0V, you are turning them fully on - lowest resistance. Basically you're shorting out the hiss, but you're shorting out the signal too.
Thanks
The 100pf cap didnt fix it, sadly.
The transistor buffer was clean when I probed it. Noise started right after
Started tinkering with the grounding and was able to remove the humming, however now I am getting quite severe clicking..
As I try different grounding schemes it seems to be a tradeoff between clicking noise and hum noise.. if I get rid of one I get the other..
I had already followed jdubs directions and placed the 100r resistor and the 22uf cap before all this. The only thing left to change would be the IC to a lower current equivalent.
When I close the lid whatever noise there is gets louder.
This is crazy ???
Tomas, I'm using an 18vac adapter into the GGG bipolar power board for mine...initially I was running it at +/- 12v and did get some ticking, but then I switched out the regulators to run it at +/- 15v and oddly enough the ticking went away. I recently switched them back to 12v, and sure enough the ticking came back. TBH, I have no idea why ??? Haven't had any hum problems, though.
I'm not quite clear how you are getting 17 volts at the inputs of your regulators using a 12vac adapter...
I have been playing around with various 9v to +/- 12 and 15v power supplies (using two LT1054s, an LT3467 like here: http://obsoletetechnology.wordpress.com/projects/studio-electronics/dc-dc-bipolar-power-supply-for-effect-pedals/ (http://obsoletetechnology.wordpress.com/projects/studio-electronics/dc-dc-bipolar-power-supply-for-effect-pedals/)) but haven't been able to get them to work quite right (usually noise problems). Juansolo did some great work getting his happening with a 9v supply, but I haven't tried it- the dc-dc converter he used isn't available in the US as far as I can tell. However, I have requested a sample of a similar unit from Murata, but don't know if they'll actually send me one- it's a $17 part. He also used the Klon buffer at the front end.
Surprisingly, considering the low input impedance, I haven't personally had much problem with high-end loss nor low output volume; it sounds pretty good to me. This one does seem to be pretty touchy noise-wise though.
Jonnyeye, thx for the buffer tips. If I get some time, I may try to adapt the layout for the addition of your buffer solution.
Thanks, I will try going for a higher voltage.
The AC adapter actually outputs 14VAC between the two poles according to my cheapo DMM. This may account for the (actually) 18.5VDC at the input of the regulator.
BTW I am talking RMS here, so 14VRMS would be 19.8V peak.
Thanks
It seems the input voltage isnt enough for the 15V regulators as noise seems to have increased. I'll go back to 12V.
I just swapped to a TL062 and the noise is pretty much the same. Also when I put another cap in parallel to the 22uF to increase capacitance, the ticking doesnt change AT ALL. Even when putting a 1000uF!
The only thing that reduces ticking is placing a small cap between pins 5&6 but thats messes too much with the LFO.
jdub, how did you ground your maestro? I believe I have a grounding or PSU problem becuase I didnt have ticking before putting it inside the case & using a new PSU.
I just grounded to the input jack, as usual...that is, once the bipolar +v, -v and 0v were attached to the board, I connected the board ground to
the jack.
A possible fix to reduce ticking that requires modifying the board:
Cut the trace from pin 4 of the LFO op-amp (the vertically oriented one at the top of the board, for reference). Run a wire from that pin to as near the -12V input as possible. My guess is that the LFO op-amp sharing a current path with the signal op-amps is what is causing the ticking.
Note that I haven't build this, but I'm planning on it as soon as I get some of my other backlog projects completed - juansolo's sample is the best phaser I've heard so far. I think it's the shape of the LFO that really does it for me. A friend of mine has a Leslie 130 which has a single bass rotor and a solid state amp that sounds great with a guitar through it (especially at low speed... subtly thick), and this gets real close to that tone while weighing about 85lbs less. Once I get mine built I may be able to help more on identifying noise sources.
I have been testing for a while and the problem is indeed the wallwart PSU.
I managed to get NO ticking with the computer PSU.
There was some ticking with the computer PSU but I managed to remove them by "filling" the ground traces with solder. I kinda created a little wall of solder between the audio and LFO traces. This reduced the ticking a great deal to my surprise. Then I placed a small sheet of aluminum on the other side of the board also between the LFO and audio components. The aluminum goes to ground. This killed the remaining ticking.
Everything is dandy when using the PC PSU, but when going back to the wallwart PSU the ticking is literally as loud as the audio signal.
What the problem with the wallwart psu??
Also, the unit is quite hissy when the effect is on. Its white noise and seems to be constant as in not affected by changing the grounding at all. The white noise drops when bypassed. Is it supposed to be like this?
Sorry for flooding this thread with posts!
PS: jonnyeye, this is by far the best sounding phaser/stompbox I have ever built. Absolutely addicting. You are spot on with the shape of the LFO being what sets it apart. Its more like a throb than a predictable sine wave. You must build it ;D
I just finished making, building, and testing the pcb for mine today. I use mine with a bass and mine has no ticking whatsoever using a walwart or my benchtop power supply. i'm running mine on +9V/-9V and it soun ds the same as running it with a bipolar 12V supply so i'm just using a a negative voltage converter to get the -9V. it has a very slight volume drop and definitely does cut the top end. I can adjust my sweep to be perfectly even with just about any Jfet. I first used 2N5485's and MPF102's but i'm now using 2N5457's for all of the jfets (since I have a TON of them). to get back the top end, i'm just going to use a tiny (and simple) Jfet buffer in front of the circuit since I already tried it that way and it sounds great with it. thanks for posting the PCB layout. this was the first one that I've ever made using the laser copier/gloss photo paper/etching method and I think that it came out great.
I slightly shrunk the width of the PCB by 'bending' some of the traces in photoshop so I can fit it into a 1590BB and it'll just fit in there now.
here's some pics of it as it is now:
the board (top):
(http://johnkvintageguitars.homestead.com/Effects/others/Maestro/PS1/01-PS-1board-top.jpg)
the bottom:
(http://johnkvintageguitars.homestead.com/Effects/others/Maestro/PS1/02-PS-1board-bottom.jpg)
the tested PCB:
(http://johnkvintageguitars.homestead.com/Effects/others/Maestro/PS1/03-PS-1board-top.jpg)
showing how it will just fit in a 1590BB:
(http://johnkvintageguitars.homestead.com/Effects/others/Maestro/PS1/04-PS1-1590B.jpg)
Looks great. Can I ask, how do you cut the pcb to size, looks like nice straight lines. I usually use a Stanley knife and a metal ruler but the end results aren't as nice as yours. Especially on fr4
johnk - that's a nice looking etch for first go. do you have any smaller drill bits?
hanging - in all instances, when working w/ fibreglass pcbs, 400ish grit wet-or-dry (wet, on glass, with gloves) is your friend. it can turn the ugliest raggedy edge into a smooth straight, better than many fab houses.
Quote from: duck_arse on August 25, 2014, 10:31:47 AM
johnk - that's a nice looking etch for first go. do you have any smaller drill bits?
hanging - in all instances, when working w/ fibreglass pcbs, 400ish grit wet-or-dry (wet, on glass, with gloves) is your friend. it can turn the ugliest raggedy edge into a smooth straight, better than many fab houses.
i wanted to get it built as quickly as i could so I just used the drill bits that I already had which are .038" (#62).
Quote from: hangingmonkey on August 25, 2014, 04:27:43 AM
Looks great. Can I ask, how do you cut the pcb to size, looks like nice straight lines. I usually use a Stanley knife and a metal ruler but the end results aren't as nice as yours. Especially on fr4
i first cut it with a dremel with #409 cutoff wheel, then i smooth the sides with a sharpening stone block.
Thanks for the tips guys! I'll try that on my next build.
She's done and it sounds awesome!
pics below:
(http://guitar-fx-layouts.42897.x6.nabble.com/file/n12658/PS1-A-01-800.jpg)
(http://guitar-fx-layouts.42897.x6.nabble.com/file/n12658/PS1-A-02-800.jpg)
johnk - great looking pedal all around and inside! Where did you get the LEDs?
Quote from: peterg on August 26, 2014, 04:39:40 PM
johnk - great looking pedal all around and inside! Where did you get the LEDs?
thanks.
those are Fresnel led lenses that I got from Mouser.
Looks killer, man. Nice work!
Thanks! and thank YOU for posting the pcb.
here's a quick and sloppy sound clip of it:
https://soundcloud.com/johnk_10/ps1-a
johnk, that looks fantastic! Nice to hear a sample with a bass, too - that's what I was thinking of using it on. Just a quick question - how did you set the trimmers? The sweep on yours sounds different than the clip juansolo posted. (It may just be the difference in FETs...)
I set the trimmer for a symmetrical sweep. the depth was set to be not too deep so that the fast setting still sounded good, and I just set/tuned the jfet bias by ear.
I just finished building this and it sounds fantastic, thanks! The six 2n5485's are still backwards on the layout fyi. I just have one problem:
The phase speed seems to be slower than in samples I've heard. Anyone have tips what could be wrong or how I can increase the over all speed of the oscillator?
Cheers!
Figured it out! Had a 20k instead of 10k connecting the first opamp stage to the second stage in the oscillator. For anyone wishing to tinker with the speeds you can adjust this resistor or change the 0.33uf cap on the first opamp stage.
johnk, you had mentioned adding a JFET buffer on the input. Did you add this in front of the existing buffer, or replace the existing buffer? Would you mind sharing the schematic?
Thanks!
Looks like the link to the corrected layout (with proper orientation of the 5485s) for this beastie is no longer working, so here's the working one: http://www.aronnelson.com/gallery/main.php/v/jdub/MaestroPS-1Alayout_zpsaeda6660.png.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/jdub/MaestroPS-1Alayout_zpsaeda6660.png.html?g2_imageViewsIndex=1)...and transfer: http://www.aronnelson.com/gallery/main.php/v/jdub/Maestro+PS-1A+transfer.png.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/jdub/Maestro+PS-1A+transfer.png.html?g2_imageViewsIndex=1). Wish I could edit the previous posts, but alas... ;D
Quote from: grenert on December 25, 2014, 08:04:02 AM
johnk, you had mentioned adding a JFET buffer on the input. Did you add this in front of the existing buffer, or replace the existing buffer? Would you mind sharing the schematic?
Thanks!
Ah, never mind. I just put a TL072 buffer in front, works great! :)
Did you use just clear LEDS with those lenses?
Hi folks,
I'm working on one of these. I have a board etched by a friend as per the PCB shown at the top on page one of this thread and referencing the schematic beneath that.
I have it going, but am having trouble understanding the speed switching operations.
I'm seeing each switch as a SPST at the moment, not worring about indicator lights or anything, I just want to understand the basic operation of the speed switching. So, comments say connect the slow and it's 'common' which I am taking as the switch pole so that the slow runs all the time and then arrange a bypass for the circuit in and out. I get that, so if that switch is thrown I should get slow phase? Looking at the schematic, the pole of the slow has a connection to ground? Is that right?
As for the medium and fast phase, once again considering the switch poles as the common, do I need to link the medium and fast switch poles? Looks like it on the schematic...
The other thing I don't get. As you move through the switches from slow to fast, how comes the fastest switch selected overrides the others, particularly if you disengage one of the slower ones? Isn't this putting resistors in parallel, so taking one out should change the overall resistance, no?
As an aside, I'm guessing that the switches could be replaced with a pot, (or a pot added along with a switch for manual or preset speed control), if I understood what's going on here I might be able to hack it in.
Thanks
Quote from: johnk on August 26, 2014, 08:35:12 PM
Thanks! and thank YOU for posting the pcb.
here's a quick and sloppy sound clip of it:
https://soundcloud.com/johnk_10/ps1-a
For The Love Of Money!
Trying to replace all resistors on my PS-1A - Does this chart look right?? I quickly went over and matched best I could
(https://s8.postimg.org/9jlrm7o2p/PS-1_A_Resistor_Identification.jpg) (https://postimg.org/image/9jlrm7o2p/)
Why are you replacing all the resistors?
Digging this one up.
The layout posted most recently in this thread purports to be the corrected one, however, the 4.7uF cap is still pointed the same way, I believe. According to the schematic, the positive leg should point towards ground. It would seem that the other issues were corrected in the most recent image though.
Another question. The pads seem separated from the traces slightly in some spots (still connected, but there are some gaps. Why is this?
IDK about the rest but those gaps is thermal design. its so you don't have to heat up the surface to much when soldering.
cheers
Quote from: jonnyeye on August 03, 2014, 04:59:13 PM
The input buffer in the original is not a great design (especially for guitar purposes) - we're talking this part right here:
(http://i573.photobucket.com/albums/ss171/jonnyeye/maestrops-1aoriginalbuffer.png) (http://s573.photobucket.com/user/jonnyeye/media/maestrops-1aoriginalbuffer.png.html)
From the design (DC coupled right to the output!) it's clear that the emitter is supposed to sit at 0V, but that depends on the hfe of the transistor used (the 2N3638A datasheet I found gives a "typical" hfe of 140, which gets to about 100mV off), and likely the reason the bias resistor to V- is given as 470k or 680k is to trim for least error - whatever the error is will appear at the output, potentially messing with whatever comes next in the signal chain and (if true bypassing is being used) causing switching pops. The input impedance is at most 33k, which will load a pickup significantly (loss of both volume and treble). And there is no RF rejection cap, so radio can get in.
What were the problems with this pedal again? :icon_lol:
The modern fix is to rip out the transistor buffer and replace it with an opamp buffer (Rpop is something 1M and up):
(http://i573.photobucket.com/albums/ss171/jonnyeye/maestrops-1aopampbuffer.png) (http://s573.photobucket.com/user/jonnyeye/media/maestrops-1aopampbuffer.png.html)
You may get away with leaving the output stock (with the 4.7k output resistor and no cap) with this one - the offset voltage should be small.
Looking at adding a buffer in and taking out the original. Does this layout make sense? Also, I am guessing that if using a TL072, I should tie pins 6 and 7 together and tie pin 5 to 0V (ground) on the board?
(https://i.postimg.cc/5XMB02ft/Buffer.png) (https://postimg.cc/5XMB02ft)
(https://i.postimg.cc/mt790W7W/Unused.png) (https://postimg.cc/mt790W7W)
Anyone?
Do you need marched JFets for this?
Decided to just use a TL071 for the buffer. Could someone please have a look a this layout and see if I have messed anything up before I etch this board? I removed the original buffer and put the TL071 buffer in there. There is also a TMR1222 Traco power supply that I have put on the board. If someone wants to have a look at that too (though it is pretty simple), I would appreciate it.
Buffer design comes from this post:
https://www.diystompboxes.com/smfforum/index.php?topic=102281.msg985795#msg985795
Power supply from this post:
https://www.diystompboxes.com/smfforum/index.php?topic=58663.msg1222071#msg1222071
Could someone just have a look? It is always good to get a second set of eyes on something.
(https://i.postimg.cc/gX7dpNcR/Maestro-Buffer-and-PS.png) (https://postimg.cc/gX7dpNcR)
Also, in relation to the output, there was talk of modifying the output resistor, would it be necessary in this case? If so, what would I change that to?
You do need a matched set of fets. If you have a look at the schematic, it indicates Q1 to Q6 have to be matched.