Arion SPH-1 - Stereo Phaser  [schematic]

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lolbou
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Post by lolbou »

Here are some guts from this phaser (did not find any on the net except for a crappy trackside). Nicely sounding I think. The plastic case seems tough enough for FX purpose. There aren't any offboard wiring apart from the battery leads...
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My first Arion so far. Chinese "Rocktek" crap is built imitating these I think...
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Post by Dirk_Hendrik »

Use the SCH1 schem for reference on the bypass and power supply circuitry and reversing should be a pretty easy job.
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Post by lolbou »

Dirk_Hendrik wrote:Use the SCH1 schem for reference on the bypass and power supply circuitry
These share the same topology then? I should look for some SCH1 pics...
Dirk_Hendrik wrote:reversing should be a pretty easy job
I'm still learning... :) Just hand-drawn a volume pedal (Boss FV-50L) yesterday: an easy start... :P I'll try to make it next holiday...

edit: just checked: the switching part doesn't have the same topology on the PCB... Let's hope it's at least the same on the schem! :wink:
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Post by poormanseverything »

Hi!

I'm new here and a complete n00b to boot so have mercy. I have this same phaser (I guess it's somewhere from the 80's, MIJ?). When I got it it worked quite well but it has developed a bad (ground) hum ... any ideas what to look for?

I remember when I got it I opened it up and there was a 'little metal thingy' which was held down by one of the four screws that hold the bottom plate - and probably needs to make contact with the circuit board?? Anyway after lending the pedal to a friend that 'metal thingy' isn't there anymore and the pedal hums badly. Do you think there's a connection here?

Can you guys please tell me where is should be connected to so I can try to wire it up!

Thanks a lot!

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Post by poormanseverything »

I meant something like this (in the photo is a CM-5 but you get the idea)

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If that's the issue it would be easy to sort I just need to know where it has to go, anyone?

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Post by rocklander »

it's likely the cause. to prove it, you could turn it on and get it 'humming' and then hold a wire from that screw (that used to hold the metal plate) to the outside of the input or output jacks.. the noise should disappear.

if that's the case you just need to solder a wire to the 'ring' lug on either jack... be sure to leave enough length to be able to work on the thing in future if you need to.
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Post by floris »

Thread revival!

I found an Arion SPH1 phaser schematic here:
http://zuzuzazuzaza.blog123.fc2.com/blog-entry-110.html
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Post by IvIark »

Looks like it's been removed, did you save it by any chance?
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Post by Dirk_Hendrik »

Right click, save as worked for me:
20110402192758802.png
Sorry. Plain out of planes.

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Post by floris »

There seem to be a lot of errors in the schematic. I'm trying to correct them.
In V1 I have focused mainly on the input section, the Vbias section with zener diode ZD2, and the on/off switch.
It is still not completely correct but better.

In order to fix my SPH1, I had to put a new IC1 dual opamp. I used a DIL8 TL072 with some wires instead of a SIP9 dual opamp.
Because the TL072 has a large input impedance, I could also fix the low input impedance of the SPH1 phaser by changing R1 (100k) into a 1M resistor.
Arion SPH1 phaser schematic - Edited by Flo V1. In V1 I have focused mainly on the input section, the Vbias section with zener diode ZD2, and the on/off switch. It is still not completely correct but better.
Arion SPH1 phaser schematic - Edited by Flo V1. In V1 I have focused mainly on the input section, the Vbias section with zener diode ZD2, and the on/off switch. It is still not completely correct but better.

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Post by FloPoeKo »

I´ve just started tinkering with the circuit. I will post a soon as I have something worth writing home about. Has anybody an Idea where to kill the dry signal in the Out1 to get a phase-vibrato? I´ve tried R27, to no avail. :scratch:

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Post by floris »

FloPoeKo wrote:... where to kill the dry signal in the Out1 to get a phase-vibrato? I´ve tried R27, to no avail. :scratch:
Try removing R66 47k Ohm. Point "W6" carries the buffered dry signal to mixer opamp 4A via R66, for output OUT .

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Post by FloPoeKo »

floris wrote:
FloPoeKo wrote:... where to kill the dry signal in the Out1 to get a phase-vibrato? I´ve tried R27, to no avail. :scratch:
Try removing R66 47k Ohm. Point "W6" carries the buffered dry signal to mixer opamp 4A via R66, for output OUT .
That worked very fine, thank you. A few observations:

Input Impedance:

The input impedance is quite low. I don´t see how changing R1 from 100kΩ to 1MΩ should help with that without significantly reducing the input level (after all, it´s a serial resistance). Wouldn´t it make more sense to have a resistor to ground before C1 (maybe as a 1-2,2MΩ pulldown-resistor in a true-bypass-arangement)?

Phase-Unit:

A) I´ve tried the values of the following Phasers for location C7/9/12/19 (Feedback disengaged at W2): Original SPH-1, Phase90/Phasetone, Univibe (Original/Wampler/Stinkfoot). These work quite well, but I wondered if R10/16/22/38 (all 10kΩ) and especially R11/15/20/39 (all 100kΩ) can/should be changed to get more closely to the respective phasers. Comparing with my Phase90 it sounded quite weak. I wondered if changing all 100k to 22k would fix that...
B) Also, I´m not quite shure how to deal with the parts in the Depth-Path of each FET (R13/14,C8 and equivalents).
C) From the looks of it, W1 would be a perfect spot to include additional Phase-Stages (if one were to go through the hustle of matching 6-8 FETS for that.) Is that correct?

Stereo-Function:

I thought that this phaser works the same as all the Arion-Stereo-Features: In Mono-Mode, both outputs have the same Mono-Signal, in Stereo-Mode output 2 carries the clean signal. Somehow it still sounded very spacey in Stereo-Mode. Did I miss anything? Is there maybe a Phase-Flip between the outputs like in some Ibanez-Stereo-Choruses I can´t identify ? I also tried Phase-Vibrato in one channel, clean signal in the other. Interesting Sound, but still not really a stereo phaser.

Low-End

Several filters could be used to shape the Low-End: C1/17/23 for the whole Effect, C18 just for the Phasing-Stage and W2 would make an excellent spot for filtering the Resonance-Path. It sounded quite ok with the full frequency-range as long a you don´t change anything else. Then you have a huge boost at max. pot setting.
I still don´t see a good spot for inserting a filter-cap at the input of the phaser stage to have a good low end in the direct, but adjust that for the phase-stage. Am I correct that putting it in the same hole with and located after R9 would make for a high-pass with R8, but anything before that also affects the direct-signal...

LFO

I´ve tried changing the LFO-Opamp in my MIS-Version (JRC 2904) to a rail-to-rail (TC2262) just like in the MIJ-Version (TA75358P). That gave a bit more swoosh, but drives the sweep into a stop at the upper end (using the BIAS-trimmer didn´t give satisfying results). Could this be changed somewhere? Getting rid of R67 could raise the supply-voltage, but that would still keep a mismatch between the two, Right?

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Post by floris »

FloPoeKo wrote:Input Impedance:
The input impedance is quite low. I don´t see how changing R1 from 100kΩ to 1MΩ should help with that without significantly reducing the input level (after all, it´s a serial resistance).
R1 is not in series with the input signal, but is parallel with it to Vbias (which for AC signals is the same as ground). See my corrected schematic please.

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Post by floris »

FloPoeKo wrote:Low-End
...
I still don´t see a good spot for inserting a filter-cap at the input of the phaser stage to have a good low end in the direct, but adjust that for the phase-stage. Am I correct that putting it in the same hole with and located after R9 would make for a high-pass with R8, but anything before that also affects the direct-signal...
You can use a series capacitor before R10 to filter out low end in the phaser stage, without changing the clean signal.

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Post by FloPoeKo »

floris wrote:
FloPoeKo wrote:Input Impedance:
The input impedance is quite low. I don´t see how changing R1 from 100kΩ to 1MΩ should help with that without significantly reducing the input level (after all, it´s a serial resistance).
R1 is not in series with the input signal, but is parallel with it to Vbias (which for AC signals is the same as ground). See my corrected schematic please.
So, I´ve changed R1, that did the job. I´ve also experimented with the values around the phase-stage for a Phase 90 Emulation:
C7/9/12/19 to 0.047 and R11/15/20/39 to 22k (this made the sweep-turnaround somehow wider at slow settings where it was a fast one before.)
Still, I´m missing some of that wonderful swoosh of my phase 90 at Depth full CW. Would jumpering R34 and equivalents or changing R13/14/C8 and equivalents in each phase stage fix that? Changing the LFO-Opamp to a TA75358 made a very nice change btw.

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Post by floris »

What nice change did the new opamp for the LFO make?

For a good "swoosh" sound :-) perhaps the bias for the FETs can be set, so that the frequency notches go as low as possible.
Modding a phaser into a Phase 90 by changing components to Phase 90 values sounds like a good idea of course.
For the rest: I guess you should try your ideas and see how you like it.

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Post by FloPoeKo »

floris wrote:What nice change did the new opamp for the LFO make?
It made for a more intense phasing compared to the NJM2904, but without stopping the sweep as with the TC2262.

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Post by FloPoeKo »

additional changes (all on sockets for easy swapping):

- R11/15/20/39 were changed from 100kΩ to 22kΩ. I can´t say for sure but I had the impression it helped with the depth. Maybe 27kΩ or the 24kΩ of the Phase 90?
- R34/35/21/40 were jumpered, which caused some serious distortion especially with humbuckers. It helped changing C1 to 0.01uF to reduce overall lowend before and also C17/23 to 0.047 after the phase-stages. Also pre-/de-emphasis and low-pass-filters (C2/C5C35/R2 as well as C22/C21) were removed. All this helped with a bit more tightness, openness and less distortion.
- I tried reducing the filter cap C34 (220/100/47/10/1µF) or leaving it out. So far, I like 10uF best of the aforementioned choices, but will test 16-22µF for middle ground. Caused a still acceptable raise in noise floor, but I felt that it gives the whole thing a bit more character (but maybe it´s just self-deception).

Still wish it would "swoosh" more like a Phase 90...

Comments greatly appreciated! :D

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Post by FloPoeKo »

I did a bit of research on the components surrounding the FET. What happens seems to be as follows:

- The JFET as a variable resistor is parallel to R11. If the FET is (very) high-impedance, R11 is seen as its nominal value (a bit less than 100kΩ) because very high impedance of the FET plus R34 in series. As the Impedance of the FET goes down to zero, R34 is in parallel to R11, so R34 should dominate with its resistance (a bit less then 4,7K). So the range of the resistance should be roughly a bit smaller than 4,7kΩ - 100kΩ and determined by R11/34.

- R13/C8 appear to be a somewhat frequency-dependent negative feedback arrangement somehow "linearizing" the transition-curve of the "variable resistor". The capacitor value in several other phasers that use this is usually higher (Ibanez Phase 909 uses 0.047µF), the values for R14 and R13 are also different (smaller).

I will see what to make of this...
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Phase 909 allpass.tiff
Phase 909 allpass.tiff (395.3 KiB) Viewed 4849 times
Phaser Arion Allpass #1.tiff
Phaser Arion Allpass #1.tiff (26.34 KiB) Viewed 4849 times

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