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 Post subject: 68k mod for Phase Royal?
PostPosted: Mon Nov 27, 2017 10:35 pm 
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I'm getting a pretty unacceptable amount of distortion (in my opinion) and am looking for solutions. I see a lot of talk concerning the Phase Royal mentioning a 68k mod in order to reduce distortion. Is this what I should try to do next? Can anyone explain exactly what this mod is and how to do it?


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PostPosted: Tue Nov 28, 2017 9:49 am 
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Do a forum search on "Phase Royal clipping" and you should find plenty of reading material.....

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PostPosted: Tue Nov 28, 2017 9:40 pm 
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Read Tark's entries and mine in this post:

http://www.byocelectronics.com/board/viewtopic.php?f=12&t=40729&p=476237#p476237

You need to skip the zener diode and R37 (a 10K) and install a 7805 zener in their place. And add a 68k resistor. The output transistor will distort a bit.
I really hate that I had to do this mod to get the thing to work properly, but I do love the phase royal now.


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PostPosted: Tue Nov 28, 2017 11:37 pm 
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The Phase Royal works properly with no mods. As detailed in many posts, the distortion is a characteristic of the original circuit.


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PostPosted: Wed Nov 29, 2017 10:17 am 
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mmarsh wrote:
The Phase Royal works properly with no mods. As detailed in many posts, the distortion is a characteristic of the original circuit.

No argument. But to be fair, not everybody likes that distortion character, especially with hotter pickups. And the Phase Royal contains several features the original MXR pedal didn't have, so it's pretty far from "vintage correct" to begin with. Just sayin'.... :wink:

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PostPosted: Wed Nov 29, 2017 10:35 am 
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OK, no argument!


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PostPosted: Wed Nov 29, 2017 9:57 pm 
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Are you saying that the mxr phase 90 -by design and/or part selection- had a starved zener? A Vref voltage that was lower than the voltage of the zener? I have found no mention of that in write-ups on the phase 90. In one of his entries, Tark expressed a reasonable theory on how this zener problem came to be.
I do not own a phase 90, but I must say I was very disappointed in the distorted (peaks only) sound of my phase royal until I stabilized the Vref and rebiased Q7 with the R68. Now I love it, but I wish BYOC could update, or at least mention the issue, in the instructions and schematic. I'm sure that's not at the top of their list, and they are a small and busy company trying to pay the bills and all that.


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