CMS Author Craig Vecchione Posted March 7, 2007 CMS Author Share Posted March 7, 2007 Why is the presence/absence of a 1/4" TRS input an issue here? The OP's guitar system has a balanced output. Treat it like an active DI output; plug it into a channel XLR. Or am I missing something? Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 7, 2007 Members Share Posted March 7, 2007 Why is the presence/absence of a 1/4" TRS input an issue here? The OP's guitar system has a balanced output. Treat it like an active DI output; plug it into a channel XLR. Well... I wouldn't have given it a second thought, except there's a new twist here I'd never thought of, being an XLR to TRS cable would have live +48v phantom on that TRS end if the board was equipped with strictly global phantom power, and if that phantom power was on, which could be a bad thing since some boards could suffer damaged from dead shorting the TRS end. So, one suggestion is to incorperate a TRS to TRS guitar cord, and then seek out a board that offers TRS inputs which either wouldn't have the possibility of phantom on the TRS inputs, or would possibly have individual channel switchable phantom. So, I've learned something new here. And I'm thinking a phantom blocker MXLR to FTRS barrel adaptor would be something to research. I'm thinking a 1:1 isolation transformer would do the trick. That would solve the Taylor guitar owners problem (fairly cheaply... cheaper than buying a TRS input equipped board)... and is something that could easily be packed along with the guitar and could be plugged into any board with complete confidence. Agedhorse: Do you have your good isolation transformers available in a MXLR to FTRS version? Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 7, 2007 CMS Author Share Posted March 7, 2007 Maybe.What you might have missed is a warning from experienced users that sometimes global phantom boards and TRS guitar (or keyboard) cords don't mix.Well... I wouldn't have given it a second thought, except there's a new twist here I'd never thought of, being an XLR to TRS cable would have live +48v phantom on that TRS end if the board was equipped with strictly global phantom power, and if that phantom power was on, which could be a bad thing since some boards could suffer damaged from dead shorting the TRS end. So, one suggestion is to incorperate a TRS to TRS guitar cord, and then seek out a board that offers TRS inputs which either wouldn't have the possibility of phantom on the TRS inputs, or would possibly have individual channel switchable phantom.So, I've learned something new here. And I'm thinking a phantom blocker MXLR to FTRS barrel adaptor would be something to research. I'm thinking a 1:1 isolation transformer would do the trick. That would solve the Taylor guitar owners problem (fairly cheaply... cheaper than buying a TRS input equipped board)... and is something that could easily be packed along with the guitar and could be plugged into any board with complete confidence.Agedhorse: Do you have your good isolation transformers available in a MXLR to FTRS version? Do we see a consensus that shorting phantom is a common issue? Keyrick provided info regarding a recording desk with a design flaw. While this is good info to know, how many of us have or have seen a live console that has problems handling a shorted XLR with phantom switched on? Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 7, 2007 Members Share Posted March 7, 2007 Do we see a consensus that shorting phantom is a common issue? Keyrick provided info regarding a recording desk with a design flaw. While this is good info to know, how many of us have or have seen a live console that has problems handling a shorted XLR with phantom switched on? Well... I was unaware that balanced TRS outputs on keyboards and guitars are common. If I could source MXLR to FTRS isolation transformers, I'm thinking I'd use them in the future to patch in such TRS equipped devices to my XLR inputs. Heck, why not? Then there's no chance for a problem. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 7, 2007 CMS Author Share Posted March 7, 2007 Well... I was unaware that balanced TRS outputs on keyboards and guitars are common. If I could source MXLR to FTRS isolation transformers, I'm thinking I'd use them in the future to patch in such TRS equipped devices to my XLR inputs. Heck, why not? Then there's no chance for a problem. I'm not convinced TRS outs are common for keys, but they are definitely not common for guitars. For example I just searched Yamaha's manuals for a keyboard with TRS balanced out. Haven't found one yet. I'm not saying it's non-existant, just that I don't think it's common. Most keyboards I've seen seem to have a pair of 1/4" outs..L/mono-R. The only balanced I've seen are XLR, and even that's comparatively rare. Essentially there's only a problem if you've got a "perfect storm" scenario...short-sensitive mixer with phantom on, and an instrument with TRS balanced output. Good to know, but nothing to lose sleep over. Lesson?: if it's got a TRS, use a DI. Link to comment Share on other sites More sharing options...
Members boomerweps Posted March 7, 2007 Members Share Posted March 7, 2007 Sliding the topic further aside, there has been several instances of XLR outs on name brand bass amplifiers NOT having the right blocking diodes installed for a few $ savings. THEN when connected directly to a board with global Phantom Power on, FRIES the amplifier preamp. Boomerweps Link to comment Share on other sites More sharing options...
Members Not Serial Posted March 7, 2007 Members Share Posted March 7, 2007 does the phantom power issue of the Fw1884 affect the Fw1804 as well? Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 7, 2007 Members Share Posted March 7, 2007 Sliding the topic further aside, there has been several instances of XLR outs on name brand bass amplifiers NOT having the right blocking diodes installed for a few $ savings. THEN when connected directly to a board with global Phantom Power on, FRIES the amplifier preamp.Boomerweps It's blocking capacitors and bleeder resistors that are required to protect the outputs from phantom power. Total of maybe $0.50 in parts cost. Not including them is just dumb... or the designer doesn't understand how the real world works. Link to comment Share on other sites More sharing options...
Members Prog Posted March 7, 2007 Members Share Posted March 7, 2007 Kurzweil, EMU, Alesis, and Line 6 PODs for quick examples of keyboards/modules with TRS outputs. Most any pro-level EQ/parametric/effects box have balanced in/outs, too. No TRS inputs on mixers have Phantom power. It is only applied to XLR channel inputs. I thought this was common knowledge. I've never seen it done any other way. I'd be very interested to see a mixing bord doing it another way. The only time I ever saw an issue was with feeding Phantom power through patch bays without XLRs. I don't remember, but they had a way of dealing with it (it wasn't 1/4 TRS connectors). It allowed patching with Phantom power being active. Link to comment Share on other sites More sharing options...
Members Keyrick Posted March 8, 2007 Members Share Posted March 8, 2007 does the phantom power issue of the Fw1884 affect the Fw1804 as well?Coaster,I have not heard of any. This problem does not exist with the newer FW-1884s either, it is only on serial numbers that start with a lower number than 012. Prog and Craigv are correct regarding balanced outs. I own a Yamaha DX7II and an S90ES and their outputs are unbalanced, as was an old CP-30 that I used to have. My Kurz PC2x, my Roland VK-8, and my Alesis Ion all have balanced outs on quarter inch TRS jacks. My Roland 1010 module is unbalanced. So, you never know until the situation arrises. When balanced is available, I use it. This usually requires making your own cables because most music stores do not carry a 20 foot TRS-TRS cable. When they do they charge about $40.00 for them! Also the Roland KC-550 Keyboard amp has balanced inputs, which is one of the reasons that I bought it.I think Mark's idea is a great one and I know I would buy a few of them if they were available. And they could be designed to accept a balanced or an unbalanced input, and would provide a poors mans DI to boot! Guitars, some guys video camera or Ipod at the wedding that you are playing at that needs to be connectd to the PA, a Sidechain effect, just about anything you would use a passive DI for. Let me know when you get them Mark, and I'll buy a couple or ten!Rick Link to comment Share on other sites More sharing options...
Members preacherman672 Posted March 8, 2007 Members Share Posted March 8, 2007 XLR and balanced TRS outputs are becoming more popular on acoustic guitars like the OP's Taylor (I own one too). An XLR/TS or maybe TRS combo jack is quite popular even on lower end models. Les Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 8, 2007 Members Share Posted March 8, 2007 Let me know when you get them Mark, and I'll buy a couple or ten!Rick I always say: Don't try to reinvent the wheel. Andy's got the inside track on GOOD isolation transformer barrel adaptors. He's your man. Link to comment Share on other sites More sharing options...
Members Keyrick Posted March 8, 2007 Members Share Posted March 8, 2007 Cool. Andy, you got such an animal? Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 8, 2007 Members Share Posted March 8, 2007 Cool. Andy, you got such an animal? I stock a lot of them, as this kind of problem comes up pretty often. E-mail me at (agedhorse@aol.com) and I will get you the info. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 8, 2007 CMS Author Share Posted March 8, 2007 This is all some interesting stuff, especially how Yamaha seems to use only TS, while Roland and Kurweil favor TRS. How many mixers do we know of that don't work and play well with a short across phantom power? Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted March 8, 2007 Members Share Posted March 8, 2007 How many mixers do we know of that don't work and play well with a short across phantom power? Good question. But IMO: If the instrument has a balanced TRS output, and the board only has XLR inputs... some sort of adaptor scheme must be implemented... so heck, why not use a isolation transformer adaptor doo-dad? I will admit that in my past, a few times I've had issues with keyboards where it seemed like I had to go to extremes to get a bit of humm out and I never knew why? Maybe I'd inadvertently been in one of these balanced TRS situations and didn't know it. I just chalked it up to Murphy dickin with me. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.