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Post by Deleted on Sept 7, 2021 14:00:50 GMT -6
You could make tie lines that bridge the XLR mic pre input panel and your TT patchbay, using open slots. You still need to keep 48V turned OFF, but you get the separation of church and state and can still plug line inputs into preamps. Upside: It's tidy, and you have two extra connectors to patch in in order to get it connected, giving you more time to ensure you're not making a mistake. Downside: it's an extra two connectors and length of cable. Or, cut out the middleman with TT-to-M-XLR cables. In the case of a 500 rack, you would want that in the XLR patch panel, too, or at least as many channels as you would want dedicated to mic pres, the rest could be in the TT. Kind of messy, but it would work. _____________ While the pedantic view on the Phantom-over-XLR-vs-TT thing is obviously correct, and is to be considered "best practice", the reality is that if it were a genuinely widespread problem, you'd hear a lot more about it. For my own design, I'm still on the fence, but ultimately it adds cost and complexity not to mention takes up more space to do the XLR thing and I might be OK to risk the tiny probability of cooking some piece of hardware as a worthwhile trade off for a simpler setup, with fewer lengths of cable and connectors. It's only ever gonna be on me if that happens and maybe I can live with that. I was just curious how others might be doing it. If an alternative solution involves a bunch of additional connections, I don't love that, but then all of these solutions are some kind of compromise. For my end of things, I'd still rather just not ever have phantom in my bay and use external phantom supplies near the mics to avoid all of these problems being discussed. The "You" in that sentence was the royal you, of course. My response is just what I would do if faced with the same needs. The cleanest would be the Bantam-to-XLR method. FWIW, I think you (the "actual" you) putting phantom boxes between pres and mics is a perfectly sensible one. Not many people are going to disable onboard phantom power in their pres, so there will always be the extra caution of making sure they are off before shoving a mix through them. That probably cannot be helped.
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Post by Quint on Sept 7, 2021 14:13:36 GMT -6
I was just curious how others might be doing it. If an alternative solution involves a bunch of additional connections, I don't love that, but then all of these solutions are some kind of compromise. For my end of things, I'd still rather just not ever have phantom in my bay and use external phantom supplies near the mics to avoid all of these problems being discussed. The "You" in that sentence was the royal you, of course. My response is just what I would do if faced with the same needs. The cleanest would be the Bantam-to-XLR method. FWIW, I think you (the "actual" you) putting phantom boxes between pres and mics is a perfectly sensible one. Not many people are going to disable onboard phantom power in their pres, so there will always be the extra caution of making sure they are off before shoving a mix through them. That probably cannot be helped. Ha, don't think I haven't thought about actually disabling the phantom on my pres. The thing with a special bantam to xlr patch cable is that you still have the issue of momentary shorting when patching things with the bantam end.
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Post by Deleted on Sept 7, 2021 14:51:09 GMT -6
The "You" in that sentence was the royal you, of course. My response is just what I would do if faced with the same needs. The cleanest would be the Bantam-to-XLR method. FWIW, I think you (the "actual" you) putting phantom boxes between pres and mics is a perfectly sensible one. Not many people are going to disable onboard phantom power in their pres, so there will always be the extra caution of making sure they are off before shoving a mix through them. That probably cannot be helped. Ha, don't think I haven't thought about actually disabling the phantom on my pres. The thing with a special bantam to xlr patch cable is that you still have the issue of momentary shorting when patching things with the bantam end. Not a risk if you plug in the bantam first, then connect the XLR end, assuming the bantam end was the output of a DAC, say.
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Post by Quint on Sept 7, 2021 14:59:05 GMT -6
Ha, don't think I haven't thought about actually disabling the phantom on my pres. The thing with a special bantam to xlr patch cable is that you still have the issue of momentary shorting when patching things with the bantam end. Not a risk if you plug in the bantam first, then connect the XLR end, assuming the bantam end was the output of a DAC, say. Yeah, but that's my point. People, including myself, forget things or accidentally cross patch things. I'd rather just remove the possibility for screw ups altogether. Anytime there's an "if" involved in something like this, there is inherent risk. In this case, the risk IS making sure that you plug the bantam in first.
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Post by Deleted on Sept 7, 2021 15:02:25 GMT -6
Not a risk if you plug in the bantam first, then connect the XLR end, assuming the bantam end was the output of a DAC, say. Yeah, but that's my point. People, including myself, forget things. I'd rather just remove the possibility for screw ups altogether. Anytime there's an "if" involved in something like this, there is inherent risk. Sure, hard to argue with that. It's for everyone to gauge their risk-aversion.
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Post by Ward on Sept 8, 2021 4:19:40 GMT -6
You mean phantom was coming out of another preamp whose output was connected to another patch point, but it was still affecting the line the 84 was connected to? Some sort of common grounding or...? Yes, I’m confused exactly what the symptoms were, but yes, I might expect a common ground issue as well… Obviously, tie line and mic preamp input grounds should all be isolated. Indeed, you both seem to have nailed it. I believe it's a couple of bad d-sub snakes.
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Post by recordingengineer on Sept 8, 2021 12:41:37 GMT -6
Been through that… Last studio I helped builld and setup has 15 Redco patchbays and a Duality; all D-Subs! Guess who soldered all of them?! Ugh! Surprisingly, I think I only had 4 or 5 fixes after all that!
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Post by Ward on Sept 8, 2021 14:29:38 GMT -6
Been through that… Last studio I helped builld and setup has 15 Redco patchbays and a Duality; all D-Subs! Guess who soldered all of them?! Ugh! Surprisingly, I think I only had 4 or 5 fixes after all that! What are your rates like? LOL
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Post by recordingengineer on Sept 8, 2021 15:54:43 GMT -6
I’m sure my hourly was pure garbage on that one, but the owner is a friend and I get to play in there as much as I want. Both of our goals is for me to work in there much much more than the tiny bit I have, but Covid has killed that so far, for the most part. We keep on being optimistic.
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Post by EmRR on Nov 11, 2021 15:48:02 GMT -6
Stumbled across this VERY GOOD POINT at GroupDIY:
Many (transformerless) mic preamps do not perform as they should because their input transistors have been subjected to zenering of their base-emitter junction. This happens when connecting an unbalanced source when phantom is on (that would be that shorted patchbay plug). The preamp seems to perform normally after that, except that noise has suddenly increased. There are well known solutions, but many designers are not well aware of them, particularly because they don't understand the problem.
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