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I have a Ibanez PH7 phaser from the tonelock series and it sounds ok but not great. I wonder why? Can it be improved?

From:
http://filters.muziq.be/model/ibanez/tonelok/ph7
Schematic:
http://www.ibanez.com/parts/2004_PARTS/ ... PH7-01.pdf

I checked the schematics and see that the PH7 is a FET phaser. Should be able to sound good, right? Perhaps the FETs should be swapped with matched ones?
FET type is a 2SK246 N-channel JFET:
http://www.datasheetcatalog.org/datashe ... a/1031.pdf
It seems to behave like a nice variable resistor looking at the Id-Vds curve.
Would some matched 2N5952 be better, like in the MXR Phase 90 tonepad project? I can't seem to find a 2N5952 datasheet with curves in it to be able to compare them.

The variable resistance used in each phase stage (Q1 and R34 for instance) is max 330k while in the MXR Phase 90 it's 22k. The capacitor value (C23) is the same: 0.047uF. That should lead to a drastic difference in the notches of the comb-filtering between these two phasers.

R32 (330k) and C22 (0.047uF) are for reducing the distortion of the FET like the in the Orange Squeezer compressor (470K and 0.0022uF) has but the used values are different. Especially the capacitor in the PH7 is much larger.

Hi, your links are wrong.

I think the link you want is this:

http://filters.muziq.be/model/ibanez/tonelok/ph7

And schematic:

http://www.ibanez.com/parts/2004_PARTS/ ... PH7-01.pdf

I used to have one of these too, and remember it sounding ok. I was going to attempt building one from that schematic as a future project, but with the flip flop switching removed and a standard true bypass setup instead. Possibly also a vibe switch if it works well.

Ah how silly of me! Thanks for the correction, I don't know why I used the de7 links...

Anyway, do you perhaps have some feedback on the observed differences with the MXR Phase 90?

I was going to attempt building one from that schematic as a future project, but with the flip flop switching removed and a standard true bypass setup instead.

Some people say that the pm7 (LM13700 OTA based 6stage phaser) sounds better. Perhaps try to build that one instead of the ph7?
http://www.ibanez.com/parts/2004_PARTS/ ... PM7-01.pdf

You're right, the PM7 does look a lot more interesting. Thanks for the tip, I'll look into it. That is, once I finish all my current projects

A four lugs POT for PM-7?

Indeed that's a weird "feedback" pot.
According to the manual: "Adjusts the amount of feedback. Turning this to the right applies normal-phase feedback, and turning it to the left applies inverted-phase feedback."

VR4-1 contains the "normal-phase" signal (via C19) and is also connected to U3B's inverting input via R53. U3B opamp is an inverter which inverts that signal into the ""inverted-phase" signal.
VR4-2 (wiper) routes the phased signal back to the input via U1A. This is the opamp that mixes the input signal and the "feedback phase" signal and then inputs the signal into the phase stages again.
VR4-3 is connected to U3B output which contains the "inverted-phase" signal.
VR4-4 (middle of the pot resistor) is connected to "virtual earth" 1/2 powersupply.

Is such a pot for sale somewhere?

One could perhaps just use a regular (mono) linear pot, connect the phased signal to one side and the inverted phased signal to the other side hoping that they will cancel each other in the middle into a null signal. But if that would work ok, Ibanez probably would have done the same...

Dear moderator, perhaps the last posts need to be split to a new "Ibanez - PM7" thread or something?

floris wrote:Indeed that's a weird "feedback" pot.
According to the manual: "Adjusts the amount of feedback. Turning this to the right applies normal-phase feedback, and turning it to the left applies inverted-phase feedback."

VR4-1 contains the "normal-phase" signal (via C19) and is also connected to U3B's inverting input via R53. U3B opamp is an inverter which inverts that signal into the ""inverted-phase" signal.
VR4-2 (wiper) routes the phased signal back to the input via U1A. This is the opamp that mixes the input signal and the "feedback phase" signal and then inputs the signal into the phase stages again.
VR4-3 is connected to U3B output which contains the "inverted-phase" signal.
VR4-4 (middle of the pot resistor) is connected to "virtual earth" 1/2 powersupply.

Is such a pot for sale somewhere?

One could perhaps just use a regular (mono) linear pot, connect the phased signal to one side and the inverted phased signal to the other side hoping that they will cancel each other in the middle into a null signal. But if that would work ok, Ibanez probably would have done the same...

Nice Floris!!

Maybe, and just maybe this POT work like a REV LOG on lug 4....

1 and 2 lugs + 4 lug Rev type - turn anti clockwise
1 and 2 lugs + 3 lug Log type - turn clockwise

Maybe a DUO LOG POT will make this job....or not!

Here the PH7 schematic without the mess connection wires.
I hope this help a bit.

Wait the download or just click in "clique aqui" link.

PH7.pdf

floris wrote:I have a Ibanez PH7 phaser from the tonelock series and it sounds ok but not great. I wonder why? Can it be improved?

From:
http://filters.muziq.be/model/ibanez/tonelok/ph7
Schematic:
http://www.ibanez.com/parts/2004_PARTS/ ... PH7-01.pdf

I checked the schematics and see that the PH7 is a FET phaser. Should be able to sound good, right? Perhaps the FETs should be swapped with matched ones?
FET type is a 2SK246 N-channel JFET:
http://www.datasheetcatalog.org/datashe ... a/1031.pdf
It seems to behave like a nice variable resistor looking at the Id-Vds curve.
Would some matched 2N5952 be better, like in the MXR Phase 90 tonepad project? I can't seem to find a 2N5952 datasheet with curves in it to be able to compare them.

The variable resistance used in each phase stage (Q1 and R34 for instance) is max 330k while in the MXR Phase 90 it's 22k. The capacitor value (C23) is the same: 0.047uF. That should lead to a drastic difference in the notches of the comb-filtering between these two phasers.

R32 (330k) and C22 (0.047uF) are for reducing the distortion of the FET like the in the Orange Squeezer compressor (470K and 0.0022uF) has but the used values are different. Especially the capacitor in the PH7 is much larger.

Very old thread I see, but:
What didn't you like about the sound of th PH-7 ?
What would you like to change?
Did you ever build one or mod one, and come up with a more pleasing result?
Did you ever build the PM-7 instead/ or something similar?

I like the PH-7 pretty well, It can be set up more useable and subtle than some other inexpensive phasers. I'm a big fan of having a mix or blend knob.

- I always preferred Small Stones to Phase-90, but I never assumed it was because OTA is inherently better than J-FET based phasing. They are voiced differently.
Standard "block-logo" Phase-90s have too much non-adjustable resonance (regen, feedback) for my taste, "script-logo" ones have less, I guess.
I have heard some very nice sounding JFET phasers.

- I'd like to see/build something with more control.
- Among fancy, high-end phasers, it seems one will bring some new feature, at the expense of leaving out some other cool feature.
I'd like to make one with: Blend/mix control, "center/sweep" control, envelope control, (with adjustable sensitivity, attack, decay..) and LFO with some control of the waveform.

I guess one thing that bugs me a little about the PH-7 is the LFO waveform. - It sounds a little asymmetrical, or perhaps triangular. - It seems to accelerate near the bottom, though it could just be my perception.. - It "throbs" a bit, in a way one wouldn't always want.. It's less noticeable at lower settings of the depth knob.

Perhaps this would be a good mod for the PH-7: An altered, or smoother LFO. - Any suggestions?

Thanks for the reply!

You know what? My taste has changed since 2008.
I'll try the PH7 and PM7 again (still have them), next time I have band pratice, and see how I like them now.
Get back to you later...

Well, I've been playing the PH-7 a lot again. - I really like it. -I'd have to say it wins for my favorite inexpensive phaser.

I love having the mix control. You can use it a lot more often than you might want a full-out, over-the-top phaser.

As long as I don't max out the depth, the LFO sounds fine.

I think the next time i build a phaser, I will either put the mix control on a big, foot-adjustable knob, or a wah shell, (I know speed would be the more obvious choice for the foot treadle, but I think I'd use mix more often...)
- Or put two pre-settable levels on a switch.

It would be really handy to be able to switch from "super-subtle" to "not so subtle."

Perhaps another LFO or an external LFO input is an idea?
For instance the Small Stone LFO.

floris wrote:Perhaps another LFO or an external LFO input is an idea?
For instance the Small Stone LFO.

I'm not too worried about the LFO. It's not bad unless you set it super high. Even then it's not bad, just not the best I've ever heard.

I probably won't mod this pedal. - It works great, & there's not much room in the enclosure.
It sounds great with the mix low, the speed slow, & depth below 75%. I'll use it like that, & use my other phasers for other things.
I have a Small Stone and a Ross on-deck to build, but no JFET phasers, (yet...)

Are folks pretty happy with the Small Stone LFO?

The thing I wanted to switch on the fly was mix, not depth. - I think I will build some form of that into my next phaser.

If you want to build a JFET phaser, probably much easier to build a Phase 90, and mod away. - You can remove the regen, or make it adjustable, I think.
Or Deadastronaut's Faze Filter.
IDK if there's an easy 6-stage JFET phaser build out there?

Of course, there's a lot of mods, & tweaks published for the Tonepad ROPEZ/ Ross, OTA-based phaser, including a board/boards for additional stages.

If you were to mod the PH7, there's no room in the box for a daughter board or anything. You could add a jack for LFO I guess, or mod the one that's in there, with different values, or add/remove components.

LFO really isn't too bad. No worse than a lot of other phasers, I guess.

It seems to speed up at the lower end of the sweep. - Maybe it's not TOO triangular, but NOT TRIANGULAR ENOUGH? - Apparently hyper-triangular sounds more "natural" to our ears?

I can think of much else to change. I think the "tone" & "phasing" sound quite good. - Not too high, not to low, and not a lot of noise, or distortion. - Gets quite lush in 6-stage mode.

That is: "can't think of much else to change" - No EDIT button?

matt239 wrote:Apparently hyper-triangular sounds more "natural" to our ears?

Yes I read this too. I found that on slower Rate settings I also prefer the "high"part of the phaser sweep to be somewhat faster than the "low" part of the sweep. This is what a hyper-triangular shaped LFO does.