tag:blogger.com,1999:blog-6847048658257278783.post3573480701402637248..comments2024-03-27T15:26:01.893+00:00Comments on Guitar FX Layouts: Maestro MPS-2 Mini Phase - ON HOLDIvIarkhttp://www.blogger.com/profile/08416945174853142251noreply@blogger.comBlogger17125tag:blogger.com,1999:blog-6847048658257278783.post-57906179956580866152023-07-24T08:24:05.387+01:002023-07-24T08:24:05.387+01:00Check the bias voltage of the oscillatorCheck the bias voltage of the oscillatorJun dhttps://www.blogger.com/profile/07905810487041216546noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-84583098281435259892018-04-29T21:15:53.097+01:002018-04-29T21:15:53.097+01:00I am currently trying to troubleshoot of of these ...I am currently trying to troubleshoot of of these circuits in the original Oberheim P-100 which is the same circuit with a DC input and the Oberheim paint job on the chassis. The issue with it is that the effect doesn't oscillate. I can here the signal out of phase and I can tweek the Oscillator Amp pot and the Bias pot and hear things change, however, I cannot get it to oscillate. What should I look for here?Andrew Hhttps://www.blogger.com/profile/13421002701513680567noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-25489197051626253942017-11-11T01:41:10.616+00:002017-11-11T01:41:10.616+00:00smallbear has em for a buck a piecesmallbear has em for a buck a piecepinksterhttps://www.blogger.com/profile/13385798043782856976noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-74912126713304323032016-11-27T08:44:41.425+00:002016-11-27T08:44:41.425+00:00why not just give a try with the original transist...why not just give a try with the original transistors<br />BaddRiddimhttps://www.blogger.com/profile/07843847228655209381noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-33782826241560137072014-04-27T02:12:48.565+01:002014-04-27T02:12:48.565+01:00Sorry John, I always respond on here, I can't ...Sorry John, I always respond on here, I can't get your email address from your Google+ page. Sounds really good to me and I'd really like to get this one verified so we could do with getting Madferret on the case to swap a few values about.<br /><br />Thanks for posting the clip, hopefully you'll be able to build an extra one soon :o)IvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-38585944469860735752014-04-27T02:05:41.270+01:002014-04-27T02:05:41.270+01:00Hey Mark, I finally saw this response. I guess i t...Hey Mark, I finally saw this response. I guess i thought I'd get an email... Anyway, a sampling of this phaser is posted here:<br /><br />https://soundcloud.com/study-shuhasko/maestro-mps-2-mini-phase-test<br /><br />Each pause between riffs indicates a change in the speed of the phase, starting at 0, followed by 3, 6, and 9 oclock and ending on full speed. The potentiometer indicator is kind of weird, it's upside down (ie instead of 12 o'clock being about 1/2 way through the turn, 6 o'clock is the halfway point.). <br /><br />Another interesting note - the resistor missing between the drain source and the JFET is really a poor idea. Even for the 2N4303s, some tweaking is needed to line up each LFO up, and the lack of a resistor results in a strange sounding turn around in the phase sweep. <br /><br />Finally, the pedal has a pretty big effect on tone. It reminds me a bit of the treble cut you'd get from an LPB-1. I think that is pretty lame for the phase effect on its own, but it really lends itself to overdrive if you're in to that.Anonymoushttps://www.blogger.com/profile/16854881263152890540noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-14631650006159254462014-03-18T15:18:39.980+00:002014-03-18T15:18:39.980+00:00Yes please, that would be excellentYes please, that would be excellentIvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-74491786502233660602014-03-18T14:52:52.220+00:002014-03-18T14:52:52.220+00:00I've got one of these! Anyone interested in he...I've got one of these! Anyone interested in hearing what the finished product should sound like?Anonymoushttps://www.blogger.com/profile/16854881263152890540noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-38705423112687101212014-03-08T00:37:00.290+00:002014-03-08T00:37:00.290+00:00Not really sure what you should be biasing them to...Not really sure what you should be biasing them to, with phasers you would usually tweak it until you get the strongest phasing. Anyway post the details in the morning and we'll see where we can get.IvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-47772569290515128382014-03-07T23:15:18.505+00:002014-03-07T23:15:18.505+00:00That'd be my interpretation of the schematic w...That'd be my interpretation of the schematic with the 100k going to the junction of the two 22k resistors but you're right it does seem odd that it wouldn't be connected to the output of the last opamp. I've had a play with a few resistors with no luck so I'm going to take a look at it with fresh eyes in the morning. I did have a look at the voltages but nothing seem out of the ordinary, I'll go over them again in the morning and write them down this time. Any idea what I should be biasing the jfets to? I've gone for 4.5v at the moment. Thanks for the help by the way, always appreciated.<br />Madferrethttps://www.blogger.com/profile/09175525273138876001noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-68272645488885606212014-03-07T22:15:49.704+00:002014-03-07T22:15:49.704+00:00Oh and I'd socket the connections but yes some...Oh and I'd socket the connections but yes something from 15K to 22K seems like a good starting place.IvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-40172314808746295142014-03-07T22:13:08.236+00:002014-03-07T22:13:08.236+00:00Yes you're right about the 2K2 and 43K mate, h...Yes you're right about the 2K2 and 43K mate, <a href="http://i76.photobucket.com/albums/j6/IvIark_2006/Layouts/Schematics/MaestroMPS-2-1.gif" rel="nofollow">here is the schematic</a>.<br /><br />Now you're probably around the area I had to question when I was doing the layout. If you look at all the other stages there is a 100K resistor between inverting input and output, but on the last one to me it looked like it went from the inverting input to the junction of those two 22K resistors and not the output because there was no dot on the schematic where it passes the output. I thought about that for a while and convinced myself that is correct as per the schematic because if there was a connection to output that would make the upper 22K superfluous. <br /><br />What are your voltages mate, just to see if they show an obvious unexpected reading somewhere.<br />IvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-54372374195602130232014-03-07T21:52:02.205+00:002014-03-07T21:52:02.205+00:00Ok, so I thought I'd give this a go this eveni...Ok, so I thought I'd give this a go this evening and kind of as expected it's not working. I'm getting the clean signal through fine but there's no 'out of phase signal' coming through. I'm guessing that the 2k2 and 43k resistors at the output are mixing the clean and phase signals so I probed just behind them both, behind the 2k2 is the clean signal but behind the 43k the signal is there but incredibly weak, I'm guessing this is why I'm not getting the phase effect at the output. I'm going to add some resistors between the drain and source of the jfets but I'm just wondering where a good starting point might be? Looking at the Phase 90 schematic it uses 22k or 24k resistors depending on the schematic so I'm going to start there but any other suggestions would be appreciated.<br />Madferrethttps://www.blogger.com/profile/09175525273138876001noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-12853645839711633872014-02-17T21:47:06.118+00:002014-02-17T21:47:06.118+00:00So so so awesome! Need to make it! Maybe futurely ...So so so awesome! Need to make it! Maybe futurely a Maestro MPF-1? :)visualdistortionhttps://www.blogger.com/profile/14517008511496080941noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-54532411259536618502014-02-17T19:23:55.631+00:002014-02-17T19:23:55.631+00:00Oops misplaced 150K at IC3, please get the correct...Oops misplaced 150K at IC3, please get the corrected layout now posted aboveIvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-57726428689908811332014-02-17T18:34:23.643+00:002014-02-17T18:34:23.643+00:00Cheers buddy :o)Cheers buddy :o)IvIarkhttps://www.blogger.com/profile/08416945174853142251noreply@blogger.comtag:blogger.com,1999:blog-6847048658257278783.post-1725443824970963452014-02-17T17:49:56.407+00:002014-02-17T17:49:56.407+00:00Very nice layout. The board size is pretty much th...Very nice layout. The board size is pretty much the same as in original.<br />+mmirosolhttps://www.blogger.com/profile/02400327798106357876noreply@blogger.com