Phase 90 Problems...

[John Egerton]

Hey guys.. I built the Phase 90 from tonepad and I can't get it to... well.. phase.

I went as far as making the whole thing again with a new board just in case i missed something but it still has the same problem...

When i'm notplaying anything... i can hear oscillation.. kinda like a theremin noise (tuning an old radio sound), only very silently though.

The guitar sound is kinda distorted when the strings are hit hard and the guitar is mainly just the original signal and no phasing whatsoever.

The FETs are matched...

I'm using 3 2n5484s together with a 2n5485, all are in the right orientation on the board...

the other standard transistor is a bc558

anyone experience similar problems?

thanks

John

[Hal]

I've never built this effect, but I think the next reply you're going to get is somebody asking for transistor voltages.  So....until somebody who knows something about this comes back, it might be a helpful thing to check :-D

[Kleber AG]

Hi,
Are you sure your diode is right oriented as in the schem?
I asked that because I remember when I built it and placed the diode "reversed" it oscilated like a theremin as well :?

Hope you get it working soon
Kleber AG

[Danny G]

I built one and it worked briefly before making only weird (but kinda cool) UFO-theremin noises which I could control in pitch with the trimpot.  I finally gave up and just built it again.  Worked like a charm the second time.

I used a 2n4125 and tried matched 2n5952s, J201s and (best sounding) BF244As.  It doesn't have the depth and sweetness of my MXR Phase 90 w/R28 mod.  

Don't think this helps, but this was my experience.

[John Egerton]

For D1 I am using your average 1n4148 and I am using a 5.1v zener.

Both are orientated correctly...

Thanks..

John

[John Egerton]

I replaced the 1n4148 diode with a different one and i'm getting it to phase now....

Its not too wooshy though...

I'm still getting that squelchy oscillating sound and I can;t help thinking that if I fix that problem... the others will be fixed also...

Does anyone have any sound samples of what the phase 90 is supposed to sound like? That way I can make comparisons....

Thanks

John

[Danny G]

It's not as present as the MXR with R28 mod.  I was hoping to replace mine with a DIY, but the MXR just sounds way better.  More "wooshy."  I abandoned my attempts at a clone and just stuck with the real thing.

[petemoore]

I replaced the 1n4148 diode with a different one and i'm getting it to phase now....

Its not too wooshy though...

I'm still getting that squelchy oscillating sound and I can;t help thinking that if I fix that problem... the others will be fixed also...
 >>>Have you taken IC voltage readings?...since you say distortion, I think a misbiased OA may do that...

Does anyone have any sound samples of what the phase 90 is supposed to sound like? That way I can make comparisons....
 >>>Mine is just Sweet PHase sound, all it does, speed control only. I never owned, and don't know how a 'real one sounds. I used the 'swap 'till it sweeps' method of Jfet picking.
 Sounds deeper than the 45, less swooshy than the EZ vibe.
Thanks

John

[Trem Abuser]

Okay, I put together the phaser kit from buildyourownclone.com.  I installed the 2N4125 transistor in one of the 2N5952 JFET slots. After realizing my mistake, I removed the 2N4125 but broke one of its legs doing so (sh*t!). Not wanting to incur the Small Bear $3.75 shipping charge on a part costing less than one dollar (and not wanting to wait to finish my phaser), I went to my local RadioShack and picked up a 2N4124 transistor (seemed to be the closest thing they had) and installed it.

So it works with the 2N4124, but there is a noticeable volume drop when I activate the phaser. [BTW, this is the second phaser kit I've put together - I previously put one together for a friend, and the previous phaser had no volume drop when the pedal was switched on.]

My question is whether this volume drop most likely due to the use of the 2N4124? I will eventually order up a 2N4125 (or perhaps a different transistor - any ideas) when I place my next order with Small Bear.

Thanks,
Scott

[Fret Wire]

My question is whether this volume drop most likely due to the use of the 2N4124? I will eventually order up a 2N4125 (or perhaps a different transistor - any ideas) when I place my next order with Small Bear.
Thanks,
Scott

I would say so. The specified 2N4125 is a PNP transistor. The 2N4124 you subbed in is a NPN transistor.

[Trem Abuser]

OK.  I read in a previous post that the 2N4126 might be preferable over the 2N4125.  Any thoughts on this?

[Fret Wire]

They are pretty close to each other, it'll work. If one is right handy locally, go ahead. Otherwise, I'd say to just stick with the specified components for now. You just got done sticking a transistor of opposite ground (NPN) where a PNP transistor should have been. So you are not checking their data sheets, or you would have caught that. Get used to checking that stuff before you go subbing or modding. The data sheets also are important to give us the lead pinouts of the transistor. They can change from one company to the next.

Go to Mouser, and type in the transistors in the search field. From there, you'll be able to link to the Data sheets. Right at the top of the sheet, it will have a brief description of the transistor, including whether it's silicon or ge, and whether it's NPN or PNP.
http://www.mouser.com/

I typed in 2n4125 and got this:
http://www.mouser.com/index.cfm?&handler=data.listcategory&D=*2n4125*&terms=2n4125&Ntt=*2n4125*&Dk=1&Ns=SField&N=0&crc=true

Then I clicked on the data sheet of the first choice and got this:
http://www.fairchildsemi.com/ds/2N/2N4125.pdf

Try it and look up the 4124. Right at the top it will say npn vs. the 4125's pnp designation.

If you're in a pinch, this one from Radio Shack should work ok.
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-2023

[Trem Abuser]

Thanks, I'll check on it.