|
I have the following setup:  From the top down, the whole list is Marantz TT 1200 turntable (ancient, stolen from my parents) Headamp 6 Pro headphone splitter DBX 215 15-band equalizer DBX 266XL 2-chan compressor Presonus Firestudio Project firewire recording interface Furman power unit and Behringer PP40 MicroPhono preamp Amplifier and speakers are not pictured. When the setup is just [turntable -> preamp -> amplifier] (all RCA) everything works as expected. I figured since I have this EQ sitting here, I might as well put that in the chain, so I can shape the sound a bit, depending on if I'm playing a recent-times Amy Winehouse record versus some old 70s Bootsy record. I'm assuming the preamp should com before the EQ (instead of the other way around), so the EQ can deal with a line-level signal. Confirm/deny? So I set up [turntable -> preamp -> EQ -> amplifier], and although everything "works" (changing the EQ bands does change the sound), I also have this noise coming out of my speakers: http://epswing.com/shared/sound.m4a. The noise in the recording changes based on moving my new-age recording device (iPhone) to the top and bottom cones of my bookshelf speaker. Maybe it's the EQ. So just for fun, I do [turntable -> preamp -> compressor -> amplifier]. Same noise. The headphone amp has a pass-thru so I try that too, [turntable -> preamp -> headphone amp -> amplifier]. Same noise. To get in/out of the EQ (and comp, and headphone amp), I'm using RCA-to-1/4" adapters:  Everything is plugged into the Furman power unit, so it's not a ground loop. Am I doing something unbelievably stupid? Help!
|
#
¿
Nov 6, 2015 01:10
|
|
|
|
| # ¿ May 16, 2024 02:26 |
|
|
Yep, the preamp has a ground screw, and the turntable's RCA cable run includes RCA-L, RCA-R, and a ground wire (which is hooked into the preamp ground screw). The turntable doesn't have a ground screw. (Aside: just curious, would it make sense for the turntable to have both a ground wire, and a ground screw? Would hooking a device's ground wire back into the device's own chassis accomplish anything?) Just clarify, when you say "try connecting them together", do you mean run some more wire from preamp ground screw to turntable chassis?
|
|
#
¿
Nov 7, 2015 01:15
|
|
|
Acid Reflux posted:And with that, I'm already out of ideas Yeah me too, I'm kind of at a loss here. As a software engineer, I'm getting that familiar feeling where "everything looks good, but the actual result is still not the expected result" which 9 times out of 10 is simply due to a lack of understanding. Are we at least pretty sure we're dealing with a loop here? Acid Reflux posted:unless maybe disconnecting the ground wire from the preamp changes something? I'll try this. Plus I'll try connecting the ground wire to the chassis of the rack itself. Will report my findings if I haven't electrocuted myself.
|
|
#
¿
Nov 7, 2015 03:56
|
|