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

frequencycentral · Post by **frequencycentral** » 28 May 2009, 13:33

I've done this layout, took a while, designed to fit into a Hammond enclosure (can't remember it's code) 4.7" L x 3.7" W x 1.34" H. (120mm x 95mm x 35mm). The layout is designed for the enclosure to be 'landscape' as opposed to portrait'. I used LM324 quad opamps to keep the size down. A 5 knob build. I know the chances are very slight - but anyone care to check it over for any obvious errors before I start building it? Once it's built and verified it would be easy for me to convert the DIYLC file to a PCB layout if anyone's interested. Thanks!

Link to GEOFEX article: http://www.geofex.com/FX_images/p180plus.gif

frequencycentral · Post by **frequencycentral** » 28 May 2009, 14:36

Here's the PCB version and PNP just for the hell of it, still needs to be verified though:

reveriesof · Post by **reveriesof** » 29 May 2009, 05:25

gorgeous layout. gonna see if i can mimic something like this for my 45! nice work, looking forward to the build

frequencycentral · Post by **frequencycentral** » 30 May 2009, 10:09

reveriesof wrote:gorgeous layout. gonna see if i can mimic something like this for my 45! nice work, looking forward to the build

Thanks! I'm really pleased with that layout, just putting it together now, though I'm missing a few parts. I'm out of 0.047uf caps!

Just a quick note, I did this layout using LM324 quad opamp packages for two reasons, one to save some space, and two because I have a bunch of LM324's that need using. TL064's and TL084's have the same pinout as LM324's so they are options too!

gmr1 · Post by **gmr1** » 30 May 2009, 14:01

looks great! I'll certainly give this a go. Does the original article mention the pot values? I'm also having trouble seeing how 5 pots work out from the above board layout. Thanks!

frequencycentral · Post by **frequencycentral** » 30 May 2009, 14:21

gmr1 wrote:looks great! I'll certainly give this a go. Does the original article mention the pot values? I'm also having trouble seeing how 5 pots work out from the above board layout. Thanks!

Thank you.

The 5 pots:

Speed: 470K
Bias: 250K (I'll be using a 100K with a 47K resistor either side of it to give a useable range)
Width: 1M (I may add a fixed resistor in series to limit the range, as a notch above the range of the instrument or speaker is a notch unheard)
Regen: 47K
Mix: 200K (I'll be using a 100K, shouldn't make any difference)

All pots are LIN.

Have a look at the schematic in the link at the bottom of my first post, all will become clear. Also have a look at my Phase Evolution thread, as the Bias and Mix work in a similar way. The Width control defines how high the sweep of the LFO goes.

frequencycentral · Post by **frequencycentral** » 01 Jun 2009, 17:55

Perf populated, now I'm waiting for the FETs to arrive, that's what the four six pin SIL sockets are for. I decided to use a BC212 PNP instead of the BC557 I listed on my layouts, as it's hfe is very close to the 2n4125 used in the original P90.

I think this is the best perf work that I've ever done:

gmr1 · Post by **gmr1** » 02 Jun 2009, 00:49

that's amazingly clean! great work. I think I'll go the pcb etching route, as my perf skills are good, but not that good! I ordered the chips and 5485's today. 200 should get me at least a couple matching sets...

bajaman · Post by **bajaman** » 02 Jun 2009, 03:43

Just a note - LM324 quad op amps are designed for single voltage rail operation - TL064, TL074 etc are designed for split rail operation.
I would use the TL064 instead - low current drain just like the LM324 but better suited to this circuit where the fets bias the non inverting pins to approximately half rail voltage. You may have some nasty distortion problems with the LM324 biasing being upset.
cheers
bajaman

frequencycentral · Post by **frequencycentral** » 02 Jun 2009, 06:05

Thanks for the tip Baj, TBH I thought this might be an issue but I thought I'd try it anyway as I have half a dozen LM324 spare. If I get issues I'll get some TL084. Gotta use those 324's for some damn thing!

Fuzzer · Post by **Fuzzer** » 02 Jun 2009, 19:56

Bajaman, the LM324 can be operated from split supply as long as the difference is between 3 and 32 [V].

frequencycentral · Post by **frequencycentral** » 02 Jun 2009, 20:18

Fuzzer wrote:Bajaman, the LM324 can be operated from split supply as long as the difference is between 3 and 32 [V].

So you're saying I'm should be good to go with the LM324's right? That's cool. 324's can be a bit odd to work with. Breadboarding stuff with a 324 doesn't mean it will work with a 084. I bought a bunch of 324's just thinking they were normal quad opamps years back, but they're not!

frequencycentral · Post by **frequencycentral** » 06 Jun 2009, 18:15

Just finished testing my build. I can confirm that the perf layout is now officially VERIFIED! Cool! Therefore, the PCB layout should also be verified, as all I did to that was copy the perf layout and replace the jumpers with traces. I can also confirm that this circuit works well with LM324, which I did have some misgivings about due to their preference for single supply rail operation, but they work just fine.

I ordered and tested thirty 2n5489 FETs, and was lucky enough to find three pretty well matched sets, with Vgs of ~1.8v, ~2.3v and ~2.5v. Having said that, I also tried some unmatched 2n5457 left over from my four stage P45 build, and it still sounded pretty good once the bias was tweaked in.

I still have to do some tweaking of the range of the Bias and Width pots. For the Bias I used a 100K pot with a 47K resistor in series at either end, I need to remove the resistor between the pot and ground, and increase the other end to 100k to put the centre bias central on the pot. I also need to reduce the 430K resistor I put in series between the Bias pot and the Width pot.

If anyone wants them, I've got two spare well matched sets of eight 2n5489, or four sets of four if you just want to build a 4 stage stock phase 90. PM me.

gmr1 · Post by **gmr1** » 07 Jun 2009, 13:05

Glad to hear it worked out! Hows it sound?

I think I'll etch a board today, and give it a go. How close do you need to get on the transistors? I have 200 to go through.

frequencycentral · Post by **frequencycentral** » 07 Jun 2009, 13:41

gmr1 wrote:Glad to hear it worked out! Hows it sound?

I think I'll etch a board today, and give it a go. How close do you need to get on the transistors? I have 200 to go through.

Sounds excellent. If you have 200 to play with you shouldn't have a problem matching. If you can match a set around 1.5 that would be splendid. My matched sets are within .1 of each other, so the 1.8 set I'm using has a range of 1.7 - 1.9. One observation, I'd go for the lowest matched set you can test, as the higher the Vgs the further to ground the Bias pot needs to be tweaked. I'm using a 100K bias pot with lug 3 to ground and a 150K resistor between vref and lug 1, the centre bias is at about 2 o'clock on the pot, I may add a higher resistor than the 150K to see if I can get it more central. I think very high Vgs FETs would require the zener to be higher rated than 5.1v.

I'm playing about with some things before I box this up, mostly offboard pots, as I want the Width pot to have a good effect throughout it's travel. I may also try decreasing the 10K feedback resistor.

Here's my circuit board with the pots mounted on a seperate piece of perf, makes it very easy to test/mod:

frequencycentral · Post by **frequencycentral** » 07 Jun 2009, 14:18

Here's the pot board layout too, it may help to explain the resistor values I'm changing to get the Bias pot and the Width pot working right:

frequencycentral · Post by **frequencycentral** » 13 Jun 2009, 13:31

gmr1 · Post by **gmr1** » 13 Jun 2009, 13:54

ha! nice. great work. did you end up sticking with the 5.1v diode? I got the PCB etched for this one, just need to build it.

frequencycentral · Post by **frequencycentral** » 13 Jun 2009, 14:03

gmr1 wrote:ha! nice. great work. did you end up sticking with the 5.1v diode? I got the PCB etched for this one, just need to build it.

Thank you!

Yes I stuck with that diode. I ended up removing R1 on the pot board (was 430K), and changing R2 to 47K. Seems about right, and sounds great. I think I'll do an eight stage Ross Phaser soon too - and no FET matching!

frequencycentral · Post by **frequencycentral** » 25 Jun 2009, 18:44

There's a couple of errors in my layout! $h!t, I'm fallible!! That's illogical Captain.

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 as in my layout.

Christ know why mine actually works (but with a couple of issues)!

I'll correct my build and the layouts over the weekend.

Sorry!