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Topic: Profex II |
Dave Moore
From:
Spring Gully, Victoria, Australia
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Posted 4 Jul 2003 7:13 am |
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I have two questions regarding the Profex II, firstly, after reading some posts on improving the noise levels of this unit, I installed some Burr Brown 2604 chips. Using my volume pedal in the FX loop, I also replaced the relative chips there with more of the 2604's as I'd read on the forum, but adding these additional chips produced a background high frequency oscillating tone. I'd be interested in a comment from Mike, or anyone who has done this as to why I get this noise.
My second question is that overall I'm really happy with the unit, but have great problems using the volume pedal in the effects loop. Is there anyway to effectively use the volume pedal in the FX loop, I seem to loose a lot of signal compared to running it between the guitar and the Profex, but want it to operate after OD & DS but before other effects. Any comments would be greatly appreciated.
Regards from downunder. |
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Ken Fox
From:
Nashville GA USA
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Posted 4 Jul 2003 9:16 am
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| I have ran it in the effects loops with no loss. You do have to set the "SEND" and "RETURN" levels at "100". Also the "SUMMED RETURN" has to be "ON" or there is about a 6db loss in volume for sure. I just set mine up and tried it. The send level is default at "50" on most settings. Also I would run the reverb and delay after the effects loop (to add a tail to the signal when the pedal is pulled back). [This message was edited by Ken Fox on 04 July 2003 at 10:45 AM.] |
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Bill Crook
From:
Goodlettsville, TN , Spending my kid's inheritance
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Posted 5 Jul 2003 1:35 pm
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Dave...........
I think you might have gone too far in trying to do a good thing to your "Profex II". We DON'T need to change all of the op-amps to 2604's.. Only the ones in the front-end signal path and freq-shapeing areas. There are other IC's that only need to process the effects perimeters and analog to digital conversions,then back to analog for output. By placeing new hi-gain op-amps (read this as Burr/Brown OPA 2604) in thses areas, we introduce much chirps,and other un-wanted electronic noise to the signal chain.
It's been a while since I've had my "Profex II" opened up so I cannot tell you just which ones should be changed but if you wish I will do so and let you which ones need to be changed. I know that u700 is one of them but I'm not too sure of all of them.
Hope this is of some help.
Bill
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Mike Brown
From:
Meridian, Mississippi USA
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Posted 8 Jul 2003 1:23 pm
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| Ditto to Bill Crooks comments. We didn't experiment with the other IC chips, only the ones in the signal path. |
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Dave Moore
From:
Spring Gully, Victoria, Australia
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Posted 8 Jul 2003 7:38 pm
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| Thanks for your comments guys. I'm still not having real success with the FX loop, seems I either have low signal, or distortion enters the equation, but I'll persist a little more yet. As for putting the additional IC's(2604's) in the unit, I did this following Ken Fox's post on June 8th, where he suggested if the FX loop is being used, that this would reduce noise, however it didn't work for me. |
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