fadercreep
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Post by fadercreep on Nov 22, 2024 16:51:41 GMT -6
I'm a big fan of 500 series, despite it being a ridiculous rabbit hole. I use my OST-8-adat daily, but it's for mixing, and it's full of eqs and compressors. I was looking to expand my 500 setup with another chassis, for preamps and other goodies, and ran across an issue for which I can find no other discussions (perhaps due to my inadequate search skills).
I use the DB25 (Tascam spec) to patch my interface output into the OST, and would expect to connect mics through the rear XLRs. In addition to recording, I would very much like to get more mileage from the preamps as reamping tone boxes like other preamps I have.
The problem is that with any DB25-equipped chassis (not just my OST from what I can tell), the DB25 also passes the phantom power because of parallel wiring, which I fully expect to fry my interface. So, regardless of chassis, I can't leave my interface patched in and use a condenser mic at the same time. For those of you who have watched Resident Alien, "That's some bullshit".
I've looked in to the VPR standard enough to know module makers use either card edge pins 7/9 or 8/10 as inputs to which the 48V is applied (and the corresponding chassis rear XLRs and DB25 inputs). It seems as though making input pins 7/9 or 8/10 selectable via switches on the chassis would solve this patching problem. Am I the only one who has gotten stuck here? Have I overlooked something or a product? Why hasn't a chassis maker designed for this?
Thanks in advance for your input (pun intended).
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ericn
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Post by ericn on Nov 22, 2024 17:10:52 GMT -6
Phantom will be present at the pre amp inputs, interface manufacturers know people are going to reamp, they know how easy it is to accidentally send phantom, so easy they are going to have some capacitors across the output that will block it.
When we had a bunch of the Fostex RP series mics I had a tech build a bunch of phantom blockers ( a pair of caps I think) into all the input tails.
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fadercreep
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Post by fadercreep on Nov 22, 2024 17:23:47 GMT -6
Thanks for the quick reply!
My correspondence with Heritage suggests not everyone is paying attention to this, as they confirmed the phantom is passed to the DB25. So is this a question to ask before buying another chassis with a DB25 input? Are there specific makers who you could recommend that protect against this, or is this a mod I need to do?
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ericn
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Post by ericn on Nov 22, 2024 18:24:24 GMT -6
Thanks for the quick reply! My correspondence with Heritage suggests not everyone is paying attention to this, as they confirmed the phantom is passed to the DB25. So is this a question to ask before buying another chassis with a DB25 input? Are there specific makers who you could recommend that protect against this, or is this a mod I need to do? Well Heritage is new to interfaces, yet kind of surprised because they build pre amps. Someone like Savart could probably draw up an easy to build Phantom blocker or dare I suggest just go with a more traditional manufacturer of interfaces, like say MOTU or Apogee? |
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Post by Blackdawg on Nov 22, 2024 18:30:24 GMT -6
Almost all 500 cards are not fully implementing the VPR features of a 500 card. It would be super cool if they did as there would be a lot of nice things that could come from that. But boils down to cost and how little most people care about those other "features" of an actually 100% VPR pinned out card. Most just say they are "compliant" with the standard using the items they want it to function in a basic setting.
I do not know, but Cemal's chassis are SUPER built out with this stuff. But not sure if the phantom goes out in parallel to all inputs or just one or two of them. Total Audio Control. Could ask him though. His chassis have 4 inputs per slot so...maybe?
Either way, the real solution here to me is just get a patch bay. Half normal it to the interface and then when you have to do a mic patch it correctly and you're good to. More money more problems I suppose.
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fadercreep
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Post by fadercreep on Nov 22, 2024 21:27:03 GMT -6
Yeah, I did think about a patch bay, but with all the i/o I have available it just seems to be an unnecessary cost. I love having everything permanently digitally patched and the convenience is freakin' awesome. I don't have an issue with the current setup, really just with the next chassis and preamps - if I go that way. The VPR spec lists 4 inputs, but these are really two balanced ins at different levels (-2, +4). From what I've learned, most preamps use the 8/10 input pins (+4) to supply 48V, but like you said, there is no forced compliance or de facto standard for this. ericn - I haven't asked my interface manufacturer (Antelope) if they protect against accidental phantom on the outputs as a result of this scenario, but I will. I just thought this would be solved (or solvable) on the chassis side. As I look at the next chassis, I will absolutely inquire with the manufacturers to understand if there is circuit protection in place against this. Thanks again for the help. |
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Post by tonycamphd on Nov 22, 2024 21:45:46 GMT -6
i may be misunderstanding, but most pre amps, converters and almost any gear these days have dc blocking caps on the inputs, if you are worried about outputs you can always check them with a meter while your phantom is on and if its not there...., bobs your uncle?
I must be misunderstanding this
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Post by Mister Chase on Nov 22, 2024 23:12:11 GMT -6
I also have had these concerns while sending converters to preamps for tone. The ones I have on my mixbus I used a Jensen pair of iso transformers. Lynx told me while there are caps on the Aurora(n) that will block phantom, it will stress them and after a while they would likely fail and be costly to replace.
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Post by Blackdawg on Nov 22, 2024 23:56:04 GMT -6
Yeah, I did think about a patch bay, but with all the i/o I have available it just seems to be an unnecessary cost. I love having everything permanently digitally patched and the convenience is freakin' awesome. I don't have an issue with the current setup, really just with the next chassis and preamps - if I go that way. The VPR spec lists 4 inputs, but these are really two balanced ins at different levels (-2, +4). From what I've learned, most preamps use the 8/10 input pins (+4) to supply 48V, but like you said, there is no forced compliance or de facto standard for this. ericn - I haven't asked my interface manufacturer (Antelope) if they protect against accidental phantom on the outputs as a result of this scenario, but I will. I just thought this would be solved (or solvable) on the chassis side. As I look at the next chassis, I will absolutely inquire with the manufacturers to understand if there is circuit protection in place against this. Thanks again for the help. If you setup the patchbay right, it'll still be like it's connected how it is now. Only when you need to intercept the signal with the a change to something else will it change. Idk. Seems the simplest solution to what you're looking for. |
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Post by doubledog on Nov 23, 2024 8:43:02 GMT -6
My Antelope interface goes from DB25 to 1/4" TRS patch bays. Then from the patch bays to my 500 chassis (either TRS to XLR ot TRS to DB25 depending on which one). The "inputs" of the 500 series boxes go to some Art P16 XLR patch bays (16 XLR per 1U). I connect the mics there. If I want to run something through the preamp at line level, then I patch out from the TRS patch panel (via TRS to XLR patch cable) and into the XLR patch panel ("inputs"). That makes me A) disconnect the mic cable, which B) reminds me to disengage phantom power on the pre. Sure, it's more wires, but never had an issue. The patch panel also allows for other flexibility - i.e., insert a compressor behind a preamp, etc. so its not just to avoid +48vdc.
You could still keep your current rack of eq/comps "direct" connected since they won't have +48. Just setup the patch panel for the new rack?
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fadercreep
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the discovery never ends
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Post by fadercreep on Nov 23, 2024 11:00:39 GMT -6
I agree - a patch bay is the simplest solution. It's just a grind that this issue hasn't been address through a standard. It may sound dumb, but a patch bay costs me rack space I don't want to have to commit and introduces more points of failure, not to mention I have to spend time patching. I guess what I'm really after are simply dedicated or switchable line and mic inputs in a 500 chassis, like on other gear I have. Apologies for the rant.
Maybe this becomes a New Year's DIY project...
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Post by thirdeye on Nov 23, 2024 11:15:42 GMT -6
I'm a big fan of 500 series, despite it being a ridiculous rabbit hole. I use my OST-8-adat daily, but it's for mixing, and it's full of eqs and compressors. I was looking to expand my 500 setup with another chassis, for preamps and other goodies, and ran across an issue for which I can find no other discussions (perhaps due to my inadequate search skills). I use the DB25 (Tascam spec) to patch my interface output into the OST, and would expect to connect mics through the rear XLRs. In addition to recording, I would very much like to get more mileage from the preamps as reamping tone boxes like other preamps I have. The problem is that with any DB25-equipped chassis (not just my OST from what I can tell), the DB25 also passes the phantom power because of parallel wiring, which I fully expect to fry my interface. So, regardless of chassis, I can't leave my interface patched in and use a condenser mic at the same time. For those of you who have watched Resident Alien, "That's some bullshit". I've looked in to the VPR standard enough to know module makers use either card edge pins 7/9 or 8/10 as inputs to which the 48V is applied (and the corresponding chassis rear XLRs and DB25 inputs). It seems as though making input pins 7/9 or 8/10 selectable via switches on the chassis would solve this patching problem. Am I the only one who has gotten stuck here? Have I overlooked something or a product? Why hasn't a chassis maker designed for this? Thanks in advance for your input (pun intended). If you were dedicated to using your XLR inputs for mics, you could possibly cut the ground wires on one side of the db25 and phantom power won't pass through. |
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fadercreep
New Member
the discovery never ends
Posts: 7
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Post by fadercreep on Nov 23, 2024 15:50:26 GMT -6
Brilliant! If removing some ground pins from a DB25 cable solves this, that's a solution I can work with. Much obliged.
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Post by tonycamphd on Nov 23, 2024 18:13:48 GMT -6
I removed all phantom power capability and dc blocking caps from the audio path from all my pres to protect ribbons and improve sound quality, I use battery power phantom boxes that stay with the condenser mics, protects everything else in turn
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Post by Mister Chase on Nov 23, 2024 18:25:13 GMT -6
I removed all phantom power capability and dc blocking caps from the audio path from all my pres to protect ribbons and improve sound quality, I use battery power phantom boxes that stay with the condenser mics, protects everything else in turn I may end up doing the same if it's not too huge a project. Wonder how hard it is to build a 48v unit with say 4-8 outputs. |
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Post by doubledog on Nov 23, 2024 19:57:46 GMT -6
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Post by tonycamphd on Nov 23, 2024 20:18:43 GMT -6
I removed all phantom power capability and dc blocking caps from the audio path from all my pres to protect ribbons and improve sound quality, I use battery power phantom boxes that stay with the condenser mics, protects everything else in turn I may end up doing the same if it's not too huge a project. Wonder how hard it is to build a 48v unit with say 4-8 outputs. I use these, they are cleaner than any phantom power that is rectified from AC and they have never gone dead on me, they claim 40 hours, i've had them up longer than that |
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Post by copperx on Nov 23, 2024 20:36:27 GMT -6
I may end up doing the same if it's not too huge a project. Wonder how hard it is to build a 48v unit with say 4-8 outputs. I use these, they are cleaner than any phantom power that is rectified from AC and they have never gone dead on me, they claim 40 hours, i've had them up longer than that These look handy when using a 1176 as a pre. |
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Post by tonycamphd on Nov 23, 2024 21:22:47 GMT -6
I use these, they are cleaner than any phantom power that is rectified from AC and they have never gone dead on me, they claim 40 hours, i've had them up longer than that These look handy when using a 1176 as a pre. I bought a bunch of them, i only have a modded MK319 and 5 samar MG33's that are condenser mics, then the Fetheads on my ribbons require phantom, everything else has PSU's or are dynamics, IMV just not worth keeping the electrolytic blocking caps in the audio path of all my good pre's |
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