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05-30-2006, 02:36 PM
| #1 |
| Member  Join Date: May 2006 Location: Eastern Washington in the Desert
Posts: 26
|  Phase 90 mods
Where's the best place to find info on these pedals? I'm trying to find a schemo or layout of the modern (new) Phase 90. I'm wanting to do the R28 mod that I've read about but I need a schem or picture or layout..something to locate the resistor in question. |
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05-31-2006, 10:18 PM
| #2 |
| Member Join Date: May 2006 Location: Eastern Washington in the Desert
Posts: 26
|  Talkin' to meself
Since I'm talkin to myself I found the modern Phase 90 Layout via a friend. It's at Youlsa.com which is in Korea. You'll have to Google and have them convert the page to English. So, I modded the Phase 90 R28 by lifting one leg off the circuit board and wow what a great difference and pedal after the mod. Very usable!! Now, why doesn't MXR make this pedal with out that resistor?? It's not very usable with it in the circuit.. BTW I found it easier to unsolder the one leg than to "snip" it as some have suggested as there's hardly any room to get a "snipper" in there. Anyone else do these Phase 90's and are there any other cool mods?? 
__________________ Turn it up! She's a good amp, just smokes a little!  |
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06-02-2006, 02:48 AM
| #3 |
| Member Join Date: May 2006 Location: Eastern Washington in the Desert
Posts: 26
| Man it is lonely in here! here! here! here! here! here! 
__________________ Turn it up! She's a good amp, just smokes a little! |
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06-02-2006, 06:14 AM
| #4 |
| Supporting Member  Join Date: May 2006 Location: San Mateo, CA
Posts: 84
| At least you've got the reverb working! Egad - I just noticed that the level above Guitar Effects is Effectification - looks like ol' tboy has been nipping at the rat cheese again... |
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06-02-2006, 04:10 PM
| #5 |
| Pickup Maker  Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
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06-05-2006, 08:37 PM
| #6 | |
| Junior Member Join Date: May 2006
Posts: 20
| Quote:
bw | |
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06-05-2006, 11:04 PM
| #7 | |
| Pickup Maker Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
| Quote:
I used to have an old script logo unit, which I liked a lot. I see the new EVH model has a switch for the script sound, which it seems has less feedback than the newer ones. | |
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06-06-2006, 03:56 AM
| #8 | |
| Junior Member Join Date: Jun 2006 Location: Boston
Posts: 8
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06-12-2006, 02:37 PM
| #9 | |
| Junior Member Join Date: May 2006
Posts: 20
| Quote:
bw | |
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06-12-2006, 05:17 PM
| #10 |
| Senior Member Join Date: May 2006
Posts: 988
| Phaser mods
A "real" phaser includes the following parametric controls: 1) rate/speed: self explanatory 2) resonance/feedback/emphasis/color: this adjusts how much of the output of the phase shift sections is fed back to the beginning to highlight/exaggerate the peaks and notches created 3) sweep width/depth: this adjusts how far the phaser sweeps upward from some predetermined starting point; the range of sweep 4) intensity/depth/mix/blend: this determines the relative proportion of phase-shifted and straight signal for subtler or more obvious effects, as wel as things like vibrato (phase-shift only) 5) initial/manual/offset: this determines the starting point of the sweep and frequency zone that the notches appear in; this is frequently linked to the depth/width control so that the less sweep width you set uit up for, the more latitude you have for manually adjusting where the sweep starts from There are certainly more things that can be included but these provide the degree of flexibility needed to mimic a broad range of phaser sounds. A lot of commercial phasers are "one-knob wonders", like the P90/P45 and Small Stone, providing only speed control (#1). Others are 2 and 3 knob units, providing controls #1 and one or both of #2 and #3. A few have 4 controls and very few few have all 5. The script/block changes pertain to a few things, but most especially to a preset amount of resonance. Think of the script-vs-block thing as if the 2 P90s each came with controls #1 and #2 and one version had control #2 tweaked a bit. I forget which version has which amount. In general, less resonance is more suitable for rhythm playing, or subtler modulation, while higher resonance lends itself more to leads. Rather than merely changing the fixed resistor to produce a fixed amount, the unit should be reconfigured with a variable control to produce not only the presets but other amouts of resonance as well. This could be done by replacing the resistor in question (the 22k value shown in red here: http://www.tonepad.com/getFile.asp?id=42) with a 12k fixed resistor and 50k variable resistor in series. This will get sounds from even more resonance than either block or script to much subtler sounds; a far more flexible unit. |
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06-12-2006, 07:40 PM
| #11 | |
| Pickup Maker Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
| Quote:
 Ah... simplicity!  This was my first phase shifter... actually this was the first phase shifter. Built by Oberheim for Gibson from a circuit drawn on a napkin by Dave Rossum of E-MU Systems. I always liked the script Phase 90... just had a nice sound. I prefer Flangers to have all the controls, but I don't mind Phase shifters with just speed... if they sound good. Otherwise you need all the controls to get them to sound the way you want. Nothing is worse than a one knob phaser with way too much feedback! Too much resonance and it sounds like a wah. The Mutron Bi-Phase sounded good with the resonance up though.  | |
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06-13-2006, 05:13 PM
| #12 |
| Member Join Date: May 2006 Location: Eastern Washington in the Desert
Posts: 26
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For those who've asked "what did the mod do?" here's the answer in layman terms. The sound was too pronounced & strong stock, also there was some distortion coming in the sound when you leaned on it hard with your guitar or keyboard. So, when I lifted the R28 from the circuit board it mellowed the pedal out a great deal. Now I could play it with my guitar and not sound silly. After the mod it sounded authentic and rich. My keyboard guy now could play it and actually turn the knob whereas before he had the knob pegged in the CC position. I don't know why they don't sell this pedal without that R28 installed as it sounds much richer, fuller, authentic & musical to my ears..HTH's
__________________ Turn it up! She's a good amp, just smokes a little! |
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06-13-2006, 08:26 PM
| #13 | |
| Pickup Maker Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
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06-13-2006, 09:03 PM
| #14 | |
| Junior Member Join Date: May 2006
Posts: 20
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06-14-2006, 06:44 PM
| #15 |
| Pickup Maker Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
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I have a circuit board layout and parts list for a script Phase 90 I did some years ago. I had to repair one (an op amp went bad) so I took some time and drew it out. Later I also owned a script model that stopped working one day. Probably also been a part failure, but I never took the time to find the part. I think I know where I put the diagram... I'll have to look for it. I figured it might be a way to buy a new unit and mod it to script specs. I'd just build one myself, but I don't feel like checking/biasing all those FETs... |
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06-14-2006, 09:14 PM
| #16 | |
| Junior Member Join Date: May 2006
Posts: 20
| Quote:
 From Nero1985, http://www.myspace.com/nero85 : Hi! Here you find out how to turn your Phase 90 that you just got a Guitar Center into the Script Phase 90 wich is not just a R28 mod or the C11 and C12 mods, it goes beyond that. There are 8 components on the new P90s that werent on the Script logo used by Eddie Van Halen and many others, here you can see what components have to be removed and wich ones replaced. Im also including a picture of its board with the component numbers so that u dont have to look for them all night long just to remove it or replace it! The Script Mod was tested by me and worked amazing, you'll get a very nice phase that might not be great as a pre distortion pedal but if u run it on ur Fx loop of after a Tube Screamer (like i do) you'll a crazy Phase! The OTHER MODS havent been tested but they should work fine. It took me a hours to realize the structure of the new P90 so i hope it helps you.... http://aronnelson.com/gallery/albums..._to_Script.gif http://aronnelson.com/gallery/albums...oard.sized.gif http://aronnelson.com/gallery/albums..._90_Script.gif http://aronnelson.com/gallery/albums...R_Phase_90.gif http://aronnelson.com/gallery/albums...oard.sized.jpg You can't really mod a block logo or reissue P-90 to script specs, as the circuits are too different (# of chips, etc). And there were more than one version of the script logo, with different numbers of chips. MXR used revision numbers on the boards, i.e. rev 108 came out in 1978, which rev is your mod? My 1974 P90 (Bud Box) has 6 chips in it as does my later 76 script logo. in 1979 they changed from 741 chips (single op amps) to TL062 duals, so # of chips was reduced. You should replace the op amps with 1458 chips for a script mod. Also: http://diy.erikhansen.net/phase90diff.htm bw | |
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06-14-2006, 09:47 PM
| #17 |
| Pickup Maker Join Date: May 2006 Location: Montclair, NJ
Posts: 4,974
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I posted a reply.. and it vanished! I had the old version with six 741 op amps, and the Bud case. That's the one I diagrammed. On the one I repaired, since I couldn't find which 741 went bad, I pulled all of them, installed sockets, and replaced them with TL071's. Worked out real nice. OK... So maybe I'll just build my own. |
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06-15-2006, 06:02 PM
| #18 |
| Senior Member Join Date: May 2006
Posts: 988
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Eastern Washington? Is that near the town of George? Just curious. Some folks want a phaser for wah-like cyclical emphasis, but some want it for gentler animation, and some - god help them - want it for both. That's why a **real** phaser has a control to vary it. The Small Stone had a 2-position Color switch that provided two resonance settings along with their corresponding sweep width setting. I suppose that gave it a big edge over the single-setting Phase 90.  The MXR Phase 100 leapfrogged over that and provided a 4-position switch that yielded combinations of two sweep width settings and two resonance settings.
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12-14-2008, 05:07 PM
| #19 |
| Member Join Date: Oct 2008 Location: Texas
Posts: 31
| Mods to the Script 90
I own a Script 90 that used to belong and used on stage by W. L. Van Zandt, of "Van Zandt" guitar pickups. He used to play lead for his cousin and a mentor of mine on the DFW area vfw circuit. He had wired in an old wall wart. I have since installed a socket for my boss power supply to run it. The hand traced circuit board has VZ pencilled in on one corner. I hate to mod it but I wont sell it, so if there is a slick way to to wire in a pot for level and perhaps depth control, I would sure like to know what the mods to the Script would be. Any ideas? Thanks in advance ENB |
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12-15-2008, 02:11 AM
| #20 |
| Senior Member Join Date: May 2006
Posts: 988
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Two kinds of "depth", or at least controls that might conceivably be labelled "depth". One is the contribution of the phase-shift channel to the mixed sound (sometimes called "Intensity" or Blend). The other is the width of the sweep. Even that can be split in different ways. It could be how high the LFO sweeps from some basic starting point. Alternatively, it could be how low the LFO sweeps from some starting point higher up. The Blend/Intensity sort of mod is easy to do. The P9 uses a pair of 150k resistors to passively mix the wet and dry signals to produce the cancellation-based notches. If you add to the basic 150k resistance on the wet side, the phase-shift effect will be less intense. A 250k pot, wired as a variable resistance, is likely sufficient to do the job. The other kind is a little trickier. Unfortunately, I know much less about it. Wiring up a volume control is a breeze, though. The standard P90 uses a 150k terminating resistor on the output. No reason on earth why that 150k resistor could not be replaced with a 100k log pot and a 51k fixed resistor from the ground lug of the pot to the circuit's ground. It would function essentially like a 150k pot that could only be turned down 2/3. Not really a problem, though. Naturally, instead of taking the output signal from the junction of the .05uf cap and 150k resistor, you would connect the pot to the cap and take the output from the wiper of the pot. |
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12-15-2008, 07:11 AM
| #21 |
| Member Join Date: Oct 2008 Location: Texas
Posts: 31
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Thanks Mark, I will investigate that when I get time to look into it. This forum is a wealth of information. Keep On Pickin, ENB |
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