andyr Posted April 8, 2017 Share Posted April 8, 2017 (edited) OK, so this arvo I was over at @djb's, mounting his Stanton 'WOS CS100' onto his newly arrived Magnepan Unitrac arm. David has 2 arms on his TT, which feed into different phono stages. So he can select which combo he wants to listen to by using the 'Source Select' switch on his preamp: is a Grado Reference Master, on an SME 3012. This feeds into an early version of my SLA-powered, JFET-based "Muse" phono stage. is the Stanton / Magnepan Unitrac (unipivot). This feeds into a Hagerman Bugle phono stage. Now, as organised above ... the sound from each cart is wonderful! But if we plug the Stanton/Unitrac combo into the Muse phono stage ... we hear a peculiar echoing warble to the sound. There's definitely something wrong! But what can it be, given: the Stanton/Unitrac combo into the Bugle sounds great - so the problem would seem not to be the Stanton cart or the Unitrac arm or the arm wiring? the Grado/SME combo into the Muse sounds great - so the problem would appear not to be the Muse phono stage? Now I know this is a 1st world problem ... but David would like to plug the Stanton/Unitrac into the Muse - as this is probably the best combination. Any suggestions as to where the problem lies? Andy Edited April 8, 2017 by andyr Link to comment Share on other sites More sharing options...
PorkBun69s Posted April 8, 2017 Share Posted April 8, 2017 I had a similar problem with my unipivot arm (Kuzma stogi s) on a Stabi TT, when it was mounted on a DIsc of silence suspension spring isolation system. Drove me nuts as i tried to debug the problem, all failed, until i just removed the discs under the isolation platform. Me thinks (just guessing here) that unipivots and suspension a bad combo? Link to comment Share on other sites More sharing options...
Wimbo Posted April 8, 2017 Share Posted April 8, 2017 Did you try swapping the Phonos around? As in move them and also swap them in the Preamp. Sounds like something is exciting the Unitrac. Link to comment Share on other sites More sharing options...
pulinap Posted April 8, 2017 Share Posted April 8, 2017 Easy.... Buy a CD player.... 9 Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 34 minutes ago, katattack74 said: I had a similar problem with my unipivot arm (Kuzma stogi s) on a Stabi TT, when it was mounted on a DIsc of silence suspension spring isolation system. Drove me nuts as i tried to debug the problem, all failed, until i just removed the discs under the isolation platform. Me thinks (just guessing here) that unipivots and suspension a bad combo? Rest assured - suspended decks and UPs work just fine. And I have exactly the same Stanton/Unitrac combo on my own suspended deck. Andy Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 26 minutes ago, pulinap said: Easy.... Buy a CD player.... Yeah, good one, P. When's your gig at the Comedy Festival - I'll come along? Andy 2 Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 29 minutes ago, Wimbo said: Did you try swapping the Phonos around? As in move them and also swap them in the Preamp. Sounds like something is exciting the Unitrac. Mmmm, don't quite follow your logic, Wimbo? If "something is exciting the Unitrac (arm)" ... then shirley it would still be exciting it when that arm is plugged into the other phono stage? But it sounds fine! Andy Link to comment Share on other sites More sharing options...
Telecine Posted April 8, 2017 Share Posted April 8, 2017 Possible problems: 1. Acoustic feedback 2. Resonance issue 3. Vibration problem 4. Input overload causing clipping on the phono stage. 1 Link to comment Share on other sites More sharing options...
Wimbo Posted April 8, 2017 Share Posted April 8, 2017 9 minutes ago, andyr said: Mmmm, don't quite follow your logic, Wimbo? With a problem like this,things need to be moved around.Just like lowering noise floors or hums by moving cables. It sounds to me that the Unitrac is being excited by something which is making it Warble. You know that Electrical energy is mechanical energy and so maybe where the Muse is located is causing the problem with the Unitrac.I'm most probably totally wrong, but changing the scenario might help. Link to comment Share on other sites More sharing options...
eltech Posted April 8, 2017 Share Posted April 8, 2017 Perhaps if you'd recorded it and uploaded it we'd be able to help more. Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 (edited) Thanks, John ... but but but ... 16 minutes ago, Telecine said: Possible problems: 1. Acoustic feedback The TT and arms were not moved - so they stayed in the same place. If this weird echoey sound is due to feedback - shirley it would be happening irrespective of which phono stage the Stanton/Unitrac is plugged into? Quote 2. Resonance issue If it's a resonance issue between the Stanton and the Unitrac: Why don't I hear it on my TT - given I use the same arm & cart? Shirley the problem would still be there, irrespective of which phono stage the arm is plugged into? Quote 3. Vibration problem Ditto. Quote 4. Input overload causing clipping on the phono stage. Yes, that's certainly a valid suggestion. The Stanton is, I think, 5mV - whereas the Grado is only 4mV. And it's the Stanton into the 'Muse' which is causing the problem. But but but ... when the Stanton was mounted on David's OL-1 arm (before the Unitrac arrived) ... it was plugged into the Muse. Which suggests overload is not the problem. And, as I said, I run the same Stanton/Unitrac combo with no issues. Regards, Andy Edited April 8, 2017 by andyr Link to comment Share on other sites More sharing options...
Telecine Posted April 8, 2017 Share Posted April 8, 2017 (edited) 5. Poor cartridge alignment Edited April 8, 2017 by Telecine Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 7 minutes ago, Wimbo said: With a problem like this,things need to be moved around.Just like lowering noise floors or hums by moving cables. It sounds to me that the Unitrac is being excited by something which is making it Warble. You know that Electrical energy is mechanical energy and so maybe where the Muse is located is causing the problem with the Unitrac.I'm most probably totally wrong, but changing the scenario might help. Sure, W, I agree that you can often solve problems like noise floor or hum by moving things around. But we "solved the problem" (of the strange echoey noise when using the Stanton/Unitrac) by simply plugging its phono cable into a different phono stage. No physical re-arrangement was needed and the phono stages, arms etc. all stayed in the same position. And the Muse phono stage is SLA-powered BTW - no mains cable, no power transformer. That's why I said I was stumped! Andy Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 21 minutes ago, Telecine said: 5. Poor cartridge alignment Mmmm - if it's poor cart alignment ... why does it sound great when plugged into the Bugle, instead of the Muse? Andy Link to comment Share on other sites More sharing options...
Full Range Posted April 8, 2017 Share Posted April 8, 2017 May have something to do with the load switch setting on the offending phono amp Link to comment Share on other sites More sharing options...
Tasebass Posted April 8, 2017 Share Posted April 8, 2017 What the...your stumped!!... Grab a third phono stage..... Move inputs around on the pre amp....and try the tape inputs if any... take the table to your place ..... Tase. Link to comment Share on other sites More sharing options...
aussievintage Posted April 8, 2017 Share Posted April 8, 2017 Maybe one phono amp has a lower/different low frequency response, allowing acoustic feedback where the other one doesn't? 1 Link to comment Share on other sites More sharing options...
gonefishing999 Posted April 8, 2017 Share Posted April 8, 2017 @ghost4man 1 Link to comment Share on other sites More sharing options...
Telecine Posted April 8, 2017 Share Posted April 8, 2017 1 hour ago, andyr said: Mmmm - if it's poor cart alignment ... why does it sound great when plugged into the Bugle, instead of the Muse? Andy What is the input sensitivity on each of the phono stages? Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 1 minute ago, Telecine said: What is the input sensitivity on each of the phono stages? Very good question. I know the gain of the two phono stages (the Bugle is a lot more than the Muse) but I don't know the input sensitivity of either. What is the definition of 'input sensitivity'? 1 hour ago, Full Range said: May have something to do with the load switch setting on the offending phono amp There are no 'load switches' on either phono stage. These are both MM phono stages with a default load of 47K. Andy Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 41 minutes ago, aussievintage said: Maybe one phono amp has a lower/different low frequency response, allowing acoustic feedback where the other one doesn't? Very interesting suggestion. The most likely one, yet! I will have to think more about what you said. Maybe the Bugle has a rolled-off bottom end which 'solves' a feedback problem which the Unitrac arm has, in David's environment? Which I don't have in my environment with the same arm and cart ... and a later version of the Muse? Andy Link to comment Share on other sites More sharing options...
HdB Posted April 8, 2017 Share Posted April 8, 2017 It wouldn't be something silly like a ground/shield different connection? Maybe something so obvious that ... Link to comment Share on other sites More sharing options...
Telecine Posted April 8, 2017 Share Posted April 8, 2017 46 minutes ago, andyr said: Very good question. I know the gain of the two phono stages (the Bugle is a lot more than the Muse) but I don't know the input sensitivity of either. What is the definition of 'input sensitivity'? There are no 'load switches' on either phono stage. These are both MM phono stages with a default load of 47K. Andy Have a read here to gain an understanding of the issue, then use the calculator: https://www.kabusa.com/pregain.htm Link to comment Share on other sites More sharing options...
andyr Posted April 8, 2017 Author Share Posted April 8, 2017 1 minute ago, jrhill said: It wouldn't be something silly like a ground/shield different connection? Maybe something so obvious that ... Of course that is possible. But: the 'echoey' noise goes away when the arm's phono cable is plugged into a different phono stage, and this 'echoey' noise is not the kind of thing (IMO) associated with grounding issues?? (The earthing wire from the Unitrac/Stanton was attached to the ground terminals of both phono stages.) Andy Link to comment Share on other sites More sharing options...
djb Posted April 8, 2017 Share Posted April 8, 2017 What would Andy do with out me, the customer from Hades? Spend time with his family? Im sure his wife thinks I'm an excuse to visit his mistress ....Maggie He misrepresents the second phono as a Bugle it is so modified by Andy that it is a Bugle Muse or a Muse Bugle ! If I had him change the power supply to a battery version it might be better than the Muse . Link to comment Share on other sites More sharing options...
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