GGG P45

[Kipper4]

Anyone made the General guitar gadgets Phase 45.
on a difficulty level out of 10 what's it like?
More importantly what does it sound like? ass or good?
I like what ive seen on you tube some of the demos are ok others are just bad so i'm confused about weither to put it on my list of to  do's.

[disabled_shredder]

I would say its a 5 on the scale only because u have to worry about matching jfets. I think it sounds great you can set it sort of slow and get almost a rocking wah kind of sweep in the midrange all the way towards vibrato. I've built 3 or 4 for my friends and they all love them. It's definitely a must if u want a phaser but don't want an evh kind of swoosh it's subtle and sort of rotary sounding.

[peterg]

I built the MXR 45 using the Tonepad schematic.

I agree with disabled_shredder's comments:

I would say its a 5 on the scale only because u have to worry about matching jfets. I think it sounds great you can set it sort of slow and get almost a rocking wah kind of sweep in the midrange all the way towards vibrato. I've built 3 or 4 for my friends and they all love them. It's definitely a must if u want a phaser but don't want an evh kind of swoosh it's subtle and sort of rotary sounding.

It turned into two projects for me. One was the 45 and the JFET matcher was the second.

Have a look at Mr. Keen's article and schematic:http://www.geofex.com/article_folders/fetmatch/fetmatch.htm

[Mark Hammer]

Finding a match for 2 JFETs is certainly easier and cheaper than finding a match for 4 (cheaper, because finding two that match does not require buying quite as many to sort through).

The P45 includes some additional circuitry, not found in the P90, that works to reduce distorting the FETs.  So, it is capable of sounding cleaner under most normal usage.

As D_S notes, the sound is less pronounced.  This partly because it is a single notch, rather than multiple notches, but also because 2 stages of phase shift affords no opportunity for including feedback/resonance.  So, it is much more of an effect suited to clean rhythm strumming than to soloing.

You can produce vibrato effects by simply lifting one end of R10.  Just note that the degree of pitch wobble produced is a function of the number of stages, and 2 stages does not produce robust pitch wobble.  You can tell its there, but you'll wish you had more.

As per the P90, R25 (3M9) can be reduced to introduce greater sweep width.  It is not unreasonable to use a toggle to place other fixed resistors in parallel to achieve narrow/wide sweep.  For instance, placing a 22M resistor in parallel with 3M9 gets you 3M3, and a 10M parallel resistor gets you 2M8, for narrow, medium, and wide sweep.  That lets you match sweep width to speed.

[deadastronaut]

The ggg version is a nice phaser.. With the fets,  ive always used j201's with no matching...unless ive just been lucky, but ive built a few.

[disabled_shredder]

I've used 5458s and 57s and a few others I used the jkm? Sight for the jfet matcher it had a board layout that was easy to perf and I think it even had an etch able pcb version. I must confess though there are a lot of mods on this forum that you could try. I personally haven't because I can't get anything to work on a breadboard. I've followed pic diagrams a million times and nothing but when I make a pcb bang works on first kill and I've done 50+ boards. Also rg mentioned the the range of fets fell in the 2.4-6 range but I could be wrong I would definitely read his article as it has great info. But all of the maybe 100 fets I've matched always fell between .85 and 1.5-6. Bottom line for me is if they match they work for the most part. But the phase 45 is an all around great pedal I use it for my cover of buddy guy/ Johnny langs mid night train where there is a wah in the first part and I think it sounds perfect. If you find yourself wanting a wah but just don't want to full w the constant footwork this pedal can be a good use. I actually built one for a bass player in a local band where i live and he loves to max it out. All in all a great pedal for a diverse pallet to express your self. And mark how do you work the resistors in parallel to widen narrow the notch?  Dpdt toggle? I really also want to do the wet dry mix mod and I saw rg had a Leslie ramp project that I think might work w this pedal any suggestions on implementation or doability. Hope the info I give is of help.

[Mark Hammer]

It's not the notch that is made wider or narrower, but the sweep.  So, narrow will sweep up and down just a little and wide will sweep way up high before coming back down.

[disabled_shredder]

My mistake on the term mark but how do you run resistors on parallel. Tie them end to end or do you run the leads from the pads to the center of a dpdt toggle and tie a 3.9m and 22m resistor on one side and a 3.9m and 10m on the other?

[Mark Hammer]

All the resistors are tied together at one end.  The free end of the extra resistors go to each outside lug of the toggle, and thhe switch common goes to the other end of the resistor on the board.

[disabled_shredder]

Mark on another p45 thread you said you could lift one end of r9 that is a 10k resistor to get a vibrato kind of effect were you referring to r9 on the ggg layout and schems or the malliet schems I tried lifting one end of r9 and got nothing also thanks for the resistor tip I wasn't to satisfied w the 2.8m sweep was a bit too narrow the 3.3 was nice though it was similar could you go to something like a 4.7m for a really long sweep or would 3.9 be somewhat the max?

[disabled_shredder]

Mark my mistake you said r10 resistor I'm guessing the resistor side that goes to the cap if memory is right. Ill lift it in the morning. You are a world of knowledge. Do you work in electronics professionally or do you just do it for fun?

[Mark Hammer]

Mark my mistake you said r10 resistor I'm guessing the resistor side that goes to the cap if memory is right. Ill lift it in the morning. You are a world of knowledge. Do you work in electronics professionally or do you just do it for fun?

There is a 10k resistor coming off the 2nd phase shift stage and another 10k resistor from the input op-amp that carries the dry signal.  Where those two 10k resistors meet is the "mixing node".  The GGG drawing refers to the 10k carrying the dry signal as R10.  If you lift either end of it, all you have left at the mixing node is phase-shifted signal.

Incidentally, since the P45 has only two stages, and vibrato tends to be subtler when fewer phase-shift stages are used, it will be helpful to include the sweep-width mod I suggested, in order to make the vibrato more noticeable.  Reducing the 3M9 resistance makes the sweep wider. 

What you'll also find, when using vibrato, is that anything slower than medium fast tends not to be detectable.  When the phase-shift is combined with clean signal so that a notch is produced, THAT will be audible at slower speeds, but the phase-shift alone is much harder to hear, unless it is faster.  I suppose that little tidbit will be helpful should you happen to wire it all up, smile when you hear a nice slow sweeping phase, then flick the vibrato switch and wonder what the hell happened and why it isn't "working".

No professional connection to electronics whatsoever.  As for doing it "for fun", I'm not sure that is an appropriate descriptor anymore.  "So, uh, do you shoot heroin for fun, or what?".

[deadastronaut]

@rich:

heres a demo of my GGG 45...just so you can hear it..

[Kipper4]

Thanks Rob Thats really nice mate. Time for me to put a tayda order in me thinks.

[Kipper4]

So you guys just replaced the jfets with J201's or 2n5458 cool I might have all the bits i need already.
I have my Iron working at the moment. Its been a nightmare. Replaced the heating element 4 times with no joy but this last one seems to be working for now so maybe tonight i'll give it a go if i can sort a perf layout.
Thanks
Rich

[Kipper4]

Shoot i dont have a 4.7 zener can i sub out with a 5.1 zener?
+ i have no 250k trimmers i'm gonna sub that too witha 500k trimmer and 500k resistor in parrallel.

[Mark Hammer]

Yeah, a 5.1 will work.

The JFETs have to be biased just right, in order to sweep in the zone you want.  The trimmer divides the supply voltage down to achieve that bias.  Trouble is, as the batterry ages, the voltage you're dividing down changes and the biasing may end up being wrong and need correction.

The zener is there to provide a stable supply voltage for the trimmer to divide down.  Once the battery drops down far enough that the zener doesn't yield a predictable voltage to divide down, the battery is likely to be too weak to power the pedal anyway.

If you are always going to power it with an external supply, then the zener may not be necessary, and a 500k trimmer will do fine.  Just note that the usable range of the trimmer may be restricted (i.e., setting up the unit could be twitchy), since you're dividing down 9v and not 4.7v (or 5.1v), and use of a 500k trimpot may drop current enough that need you to adjust the value of the 1M resistor that feeds the JFETs.

But it should work.

[Kipper4]

thanks Mark.
I'll use the 5.1v zener then
I socketed the zener so i can change it out if i so wish later.
I'm half way through the build now.
I decided to go with a differant layout.
Tone pads but a perf layout. called mini phase 45
this one
http://solderman.fatabur.se/Mini_ph45/Mini%20_Phaser_45_Projectfile.pdf
tbh its a bit messy but i'm sure i'll figure it

[Kipper4]

I'm confused over the jumper that bridges Q1 and C9 anode
do you guys think it just goes straight from one to the other ?
The layouts in my last post
Thanks
Rich

[disabled_shredder]

From looking at it run some jumper wire from emitter of q1 to neg of c9 do it on the underside you could do it on top but you would want that wire to fall under everything unless you don't care about looks but don't run bare wire either way you will have a short if you do.