Coytee Posted November 11, 2007 Share Posted November 11, 2007 This is what the EV-38 owners manual says on page 3-1 regarding unbalanced (which again, is my input mode from Peach/RCA to Dx-38/XLR) "It is also possible to operate the appliance in unbalanced input/output configuration. Therefore, the cable's "HOT" conductor has to be connected to pin 2 and the screen to pin 1 of the XLR-type connector. To prevent the level being attenuated by 6db, you have to short-circuit pins 1 and 3 of the XLR-type connector. In case this measure leads to interference noise, removing this connection is recommended." The drawings, if I interpret them correctly, show an RCA jack on one side with hot/+/pin 2 going to it's center pin. On the XLR side it has hot/+ going to pin 2, pin 3 is "-" and what I would call negative. Pin 1 is what I'd call ground. I think they refer to it as the sheath. What I've done is wire the 3 wires to each pin on the XLR side and instead of grounding pin 1 and the screen together on the XLR connector, I've merged them into a single wire mass on the RCA side and soldered them both to the ground. I figured that would be the same thing. So, according to the book, we have: On the XLR side, pin 1 = sheath, pin 2 = hot and pin 3 = negative. On the RCA side, the black lead from hot/pin 2 goes to the center pin and again, in MY case, the other TWO wires are blended together into ONE wire, being soldered to the ground (outer circle) of the RCA jack. Now, above in the instructions, it says "in case this measure leads to interference noise, removing this connection is recommended"... Remember now, that my XLR is individually wired with no short wire. Do I need to redo these alltogether or (as I've done) can I snip the SHEATH wire on the XLR connector. Doing this, gives me +/- ONLY on the XLR side (leaving the sheath hanging in midair) and on the RCA side, I've got the -/sheath soldered to the ground on the RCA pin BUT again, the other end of the sheath is no longer connected (on the XLR side) gack.... Snipping the sheath from the XLR DID in fact, get rid of the loud (very intrusive) noise I was having however, NOW I still have a background, low volume ground loop type hum. Turn the sound up at all and it's hard to hear however it's still there. For those who say "just go buy a pair", I most likely will. Didn't have a chance last week which is why I went ahead & went into this. Aside from that, I'm more stubborn than that and like to delve into something & figure it out. It's how I learn. So... Did I snip the proper wire (sheath) on the XLR side? Should I rewire my RCA side and disconnect the sheath on that side, reattaching it back on the XLR side? Did I screw up and should I have cut the "-" wire instead? (pin 3) When you're done answering this, you can resume your discussions about which topology (SET/SS/PP) will best roast Amy's duck, Dwight. [:|] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 your not saying where the XLR's are going to. If they are going to the MC-2102, which has fully balanced inputs via dedicated seperate tubes for pin 1 and pin 3...I'm not sure I would short out pin 1 and pin 3...the mc-2102 expects an inverted signal along with a noninverted signal. If you are connecting an RCA device to your MC-2102...why not just switch the MC-2102 into RCA mode? Simular questions if we are talking about a different input. Balanced connections are just that....inverted and noninverted...RCA outputs are not inverted...you can use autoformers...transformers...and even resistors to fool the XLR balanced input at the cost of line levels. This is what you need if you want to convert an unbalanced signal to balanced one..... http://www.musiciansfriend.com/product/ART-CleanBOX-Two-Way-Stereo-Converter?sku=180613 Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 11, 2007 Author Share Posted November 11, 2007 To show my ignorance...I'll admit I'm lost on exactly what you're saying. I thought I DID mention where these wires are going? They're patched as the initial output of my Peach going into the input of my Dx-38. My Peach has RCA outputs and the DX has XLR inputs/outputs. Did you miss that or do I misunderstand your question? I'm beginning to think based on the above comment from the manual that they (EV) leave a bit of wiggle room as to how to wire the cord, depending on if you have noise or not. I DO have some noise and am not sure which wire they really want me to snip. Well, they mention snipping the bridge wire on the XLR, does that mean I would have the negative and the sheath STILL wound together & soldered to the ground on the RCA pin? Fritz, I DO have one of those Art boxes however it seems it really magnifies some noise in my system. Right now I'm just thinking I've been stupid and wired this XLR/RCA wrong. (maybe I've just got a noisy tube and haven't thought to look that way??? is that possible?) Now, as per the 2102, as of THIS specific moment in time, it's not in the system and I'm using four XLR/RCA outputs to a dbx BX-3 amp (4 channel). I wanted to see how this amp would work for a while. When I throw the 2102 back into the mix I've got another set of XLR/XLR wires that I'll use from the outputs of the Dx-38. Now that I've also got the Crown K2, I can run the same XLR/XLR wires to it. Right now however, I'm specifically taking those XLR based amps out to see what happens with this 4 channel amp (and thus far I must admit to having more headaches []) Although I'm not there yet (because I AM so hard headed), the thought of "is this really worth it" is starting to creap out on the horizon of my hearing. I just get so dang determined to conquer something when it tries to trip me up... that's what I'm facing now... it's becoming a matter of principle that this stupid little wire keeps kicking my hiney [:'(] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 Ok, so you have an tube pre-amp that only has RCA out going into a dx-38 which has xlr in. I attached a tube pre schematic which has XLR and RCA to explain the inverted/non inverted scheme of balanced lines. On this schemtic, pin 1 of the XLR goes to ground, the sheild of the RCA is shown as also going to ground , pin 2 of the XLR goes to the non inverted side of the XLR circut, as does the center pin of the RCA connector, pin 3 of the XLR however goes to the inverted side of the board where the signal gets thrown 180 degrees out of phase. So shorting out pins 1 and 3 on an XLR connector that uses true balanced (inverted/noninverted) could be problemmatic. You need a method that either loads 1 and 3 with resistors, transformers, or autoformers. Your RCA center cable would connect center of the load point. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 one of two Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 two of two Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 if you tried both of these methods and get a hum...try it with out pin 3 connected. Pin 3 is the inverted signal lead. Some equipment use inverted signals. Others just load pin 3 with either a transformer, resistor, or a semi conductor device. Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 11, 2007 Author Share Posted November 11, 2007 Ok...now we're getting somewhere but I'll still confess to some confusion as to meanings. The SECOND picture (two of two) is EXACTLY how I wired it. From what I did and what I think you're saying... it would seem as though I snipped the wrong wire? I snipped the sheath and left the white wire attached to pin 3. you're saying cut pin 3 which (I think) which is my white/negative wire as opposed to being what I'd call the ground/sheath wire (which is the one I cut) Is that what you're saying? Now...here's the tricky part.... If I'm setup like picture two of two, both pin 1 and 3 are merged onto the grounding part of the RCA plug. Will that matter if I only cut the wire at pin 3 and leave it merged on the RCA side of the wire? (things like this, you gotta talk to me like you would your 7 year old... well... maybe your 5 year old) [] Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 11, 2007 Share Posted November 11, 2007 Richard, You want to cut the one on pin 3, NOT the sheath or screen on pin 1. Pin 1 is the ground. It shouldn't matter leaving the extra wire in the cable and snipping at the xlr end. Will it act like an antenna? Maybe, maybe not. Look under two channel at my recent post on connector pinouts. The 6th item down is what you are showing. I thought this document might be a good reference for folks. Bruce Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 11, 2007 Share Posted November 11, 2007 ditto to what Marvel said.... also...there is a lot of confusion out there on cutting one side of the pin 1 connection and leaving it connected on one end....I'd side bar that for now and...there may be some confusion on the pin numbers/functions of the female connector vs the male connector...the female connector is 2/3/1 counter clockwise and the male connector is 1/3/2 counter clockwise, key ways being at the 3 o'clock position. Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 11, 2007 Share Posted November 11, 2007 ditto what speakerfritz said... [Y] Most of the XLRs I have seen have the numbers on the plastic insert, but they are sometimes hard to see. I used to wire up microphone cables all the time, and made a little jig to hold the connector in place while I did my soldering. Even if you only do a few, it saves a lot of headaches. Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 13, 2007 Author Share Posted November 13, 2007 Just an update... Went to store to buy a XLR/RCA wire... of course they wre out of stock. He tried to sell me a transformer box (much like the Artbox I've already got...or was it "Cleanbox?") Anyway... Came home & rewired the XLR, hooking up the end I'd clipped off and removing the other on the XLR cable. Still had same noise. Finally said heck with it and installed the Artbox I've already got. Why I don't listen to others sooner is beyond me... problem is now gone. [Y] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 13, 2007 Share Posted November 13, 2007 ""Came home & rewired the XLR, hooking up the end I'd clipped off and removing the other on the XLR cable. Still had same noise. Finally said heck with it and installed the Artbox I've already got. Why I don't listen to others sooner is beyond me... problem is now gone."" so at least you ruled out problems with you gear and outlets.....you confirmed your noise to be associated with the various approaches to wire RCA to XLR... Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 13, 2007 Author Share Posted November 13, 2007 Yep Fritz... seems something didn't like the XLR/RCA wire at all. It DOES create another question with me in that, I've now got this cleanbox between my Peach and Dx-38 and no noise. The Dx-38 has 4 XLR outputs and connected to THOSE, are 4 wires with XLR's on the Dx side and (yuck yuck) RCA's on the amp side. (connected to my 4 channel dbx BX-3) So, why everything had such a hissy fit when I had some XLR/RCA wires connected between the preamp & xover, yet no one (electric components) seems to have any problems with FOUR XLR/RCA wires between the xover and my power amp is beyond me. Seems like a double standard. I'm open to thoughts! Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 13, 2007 Share Posted November 13, 2007 another way of looking at this would be to wonder what the cleanbox would do to the side that seems like it's ok. Would it make that quieter as well? does it need to be? Quote Link to comment Share on other sites More sharing options...
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