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Post by jakeharris on May 25, 2017 10:12:50 GMT -6
Have you changed the cable, and tube to EF86? Tube was always an EF86. Swapped tubes from original 67 to the TLM, no real difference. Cable is a 7 pin Gotham tube mic cable, probably only 15' long. I changed the output transformer and it sounds very close to the real 67, meaning the supplied BV-12 was rolling off a lot of top end. Cool, was asking because that standard China cable is dark as hell. Cables are cables, it shouldn't do this and that, sure. But this one very noticeably rolls off the highs on a 5m length. Swap with a Gotham/Sommer like you did, and the highs always open up.
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Post by ragan on May 25, 2017 11:45:34 GMT -6
Tube was always an EF86. Swapped tubes from original 67 to the TLM, no real difference. Cable is a 7 pin Gotham tube mic cable, probably only 15' long. I changed the output transformer and it sounds very close to the real 67, meaning the supplied BV-12 was rolling off a lot of top end. Cool, was asking because that standard China cable is dark as hell. Cables are cables, it shouldn't do this and that, sure. But this one very noticeably rolls off the highs on a 5m length. Swap with a Gotham/Sommer like you did, and the highs always open up. You have solid documentation on this? I'm not disputing it, just curious what your comparison setup was like. Can tube mic cables affect sound, like, for real, or is it like a balanced cable where one sounds More Open and one has More Midrange Detail and one has a Tighter Low End but they all null ? I have zero knowledge of tube mic PSU cables and what they do/don't do, but if it's real, I'd try a swap I suppose. Gimme the scoop!
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Post by EmRR on May 25, 2017 11:56:08 GMT -6
Some cheaper cables have much higher capacitance between windings, could roll off top if long enough. I think Gotham isolates filament and B+ from audio better, as does a Canare.
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Post by svart on May 25, 2017 12:19:34 GMT -6
I've even used MIDI cable for my mics before when I've run out of multi-cored mic cable. Can't say I've ever heard a difference.
You're more likely to have crosstalk of noise than "darkening" of a signal.
Remember, that the low-pass filter effect requires significant coupling to a "stiff" plane/trace/conductor (can be ground/shield or power) for some considerable distance. I don't remember which thread it was, but I figured the estimated LPF frequencies over cable distance for various types of audio cables. The gist of the math was that for most cables with a significantly high conductor-to-shield capacitance, the LPF effect didn't matter until the cable was in the *hundred foot* range or more when using standard mic output impedance into an estimated preamp input impedance.
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Post by jakeharris on May 25, 2017 13:34:11 GMT -6
Cool, was asking because that standard China cable is dark as hell. Cables are cables, it shouldn't do this and that, sure. But this one very noticeably rolls off the highs on a 5m length. Swap with a Gotham/Sommer like you did, and the highs always open up. You have solid documentation on this? I'm not disputing it, just curious what your comparison setup was like. Can tube mic cables affect sound, like, for real, or is it like a balanced cable where one sounds More Open and one has More Midrange Detail and one has a Tighter Low End but they all null ? I have zero knowledge of tube mic PSU cables and what they do/don't do, but if it's real, I'd try a swap I suppose. Gimme the scoop! No, it's fake. I just like talking bullshit on the internet... The concise version: A normal cable doesn't drop 0.5 to 1V on the filament over 20-25 feet, and it doesn't darken the sound. This Chinese cable does both. It's not a normal cable. But please try it for yourself. No need for test setups, difference isn't subtle, and no need to break the bank. We're talking $4-$5/meter.
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Post by svart on May 25, 2017 13:45:37 GMT -6
You have solid documentation on this? I'm not disputing it, just curious what your comparison setup was like. Can tube mic cables affect sound, like, for real, or is it like a balanced cable where one sounds More Open and one has More Midrange Detail and one has a Tighter Low End but they all null ? I have zero knowledge of tube mic PSU cables and what they do/don't do, but if it's real, I'd try a swap I suppose. Gimme the scoop! No, it's fake. I just like talking bullshit on the internet... The concise version: A normal cable doesn't drop 0.5 to 1V on the filament over 20-25 feet, and it doesn't darken the sound. This Chinese cable does both. It's not a normal cable. But please try it for yourself. No need for test setups, difference isn't subtle, and no need to break the bank. We're talking $4-$5/meter. That cable clearly has something wrong with it. I'd wager it has multiple shield strands shorting other conductors out. There is no way 20-25ft of cable could drop that much voltage, nor act as a LPF without some kind of shorting going on.
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Post by EmRR on May 25, 2017 13:49:08 GMT -6
I might put it another way: 'normal' cable is what the Chinese stuff is, and lacks the wire size for filament current without voltage loss over distance. The Gotham stuff is 'specialized' cable with larger wire size for filament current, and standard wire size for audio.
In of itself a 0.5-1V drop on filaments isn't ideal, but it shouldn't cause any effect other than longer initial heating times. There's likely some U67 expert commentary on that which goes into detail, though I haven't seen it. All depends on the tube and the usage.
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Post by jakeharris on May 25, 2017 14:01:16 GMT -6
No, it's fake. I just like talking bullshit on the internet... The concise version: A normal cable doesn't drop 0.5 to 1V on the filament over 20-25 feet, and it doesn't darken the sound. This Chinese cable does both. It's not a normal cable. But please try it for yourself. No need for test setups, difference isn't subtle, and no need to break the bank. We're talking $4-$5/meter. That cable clearly has something wrong with it. I'd wager it has multiple shield strands shorting other conductors out. There is no way 20-25ft of cable could drop that much voltage, nor act as a LPF without some kind of shorting going on. "There is no way"... except every single China cable does it. Why do you think the filaments in these China PSU's are all set to 6.7v??
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Post by Ward on May 25, 2017 14:03:56 GMT -6
It seems to me that if Neumann (Sennheiser) can do a great job reissuing the 47FET, they could do just as well with a U67 if they wanted to. With the U87 and TLM 67 still in production, I'd guess it wouldn't be a huge leap for them to add tube circuitry, the body and capsule are the same, aren't they? The reissue would probably street for $9K . . . bad enough I bought 2 U47fet reissues.
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Post by jakeharris on May 25, 2017 14:14:36 GMT -6
In of itself a 0.5-1V drop on filaments isn't ideal, but it shouldn't cause any effect other than longer initial heating times. There's likely some U67 expert commentary on that which goes into detail, though I haven't seen it. All depends on the tube and the usage. There is one big problem; if you swap out standard China cables without modifying the heater voltage, you'll hit your tube with 6.7v @ 15ft. @ 25ft, it's probably still seeing 6.5-6.6v. That shortens tube life, and changes the sound. I don't know if Max has modded these PSU's, but an easy check is to look for a diode on the ground leg of the 7806. If it's there, then you have 6v + 0,75v. (I don't think he's using 7906's, he's flipping the polarity of a few PCB traces instead)
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Post by svart on May 25, 2017 14:23:06 GMT -6
That cable clearly has something wrong with it. I'd wager it has multiple shield strands shorting other conductors out. There is no way 20-25ft of cable could drop that much voltage, nor act as a LPF without some kind of shorting going on. "There is no way"... except every single China cable does it. Why do you think the filaments in these China PSU's are all set to 6.7v?? Except for the ones I'm using I guess.. Because those seem perfectly normal.
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Post by EmRR on May 25, 2017 14:33:51 GMT -6
In of itself a 0.5-1V drop on filaments isn't ideal, but it shouldn't cause any effect other than longer initial heating times. There's likely some U67 expert commentary on that which goes into detail, though I haven't seen it. All depends on the tube and the usage. There is one big problem; if you swap out standard China cables without modifying the heater voltage, you'll hit your tube with 6.7v @ 15ft. @ 25ft, it's probably still seeing 6.5-6.6v. That shortens tube life, and changes the sound. I don't know if Max has modded these PSU's, but an easy check is to look for a diode on the ground leg of the 7806. If it's there, then you have 6v + 0,75v. I'd have to go back and look, but I recall voltage being correct range. Good point on higher capacity cable, no different from what we consider with any power loom in any situation; 500 rack, console, etc. One could also argue the Chinese cable is 'factory matched' to the PSU voltage, if the result at the tube is correct. Doesn't address any audio issue. 6.5-6.6V is indeed in spec (6-6.6V), and does not significantly change tube life. It's not design center (virtually NOTHING ever is), but it's not out of spec either. PF86 / EF86 switch: resistor inline to drop voltage for PF86. Another possible place to tweak voltage.
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Post by jakeharris on May 25, 2017 17:27:27 GMT -6
"There is no way"... except every single China cable does it. Why do you think the filaments in these China PSU's are all set to 6.7v?? Except for the ones I'm using I guess.. Because those seem perfectly normal. If you haven't directly compared to a Gotham or Sommer cable, I'm not sure how you know what normal is... Both those cables sound identical btw.
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Post by Johnkenn on May 25, 2017 17:37:11 GMT -6
We got some real badasses in here, huh?
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Post by jakeharris on May 25, 2017 17:41:56 GMT -6
I'd have to go back and look, but I recall voltage being correct range. Good point on higher capacity cable, no different from what we consider with any power loom in any situation; 500 rack, console, etc. One could also argue the Chinese cable is 'factory matched' to the PSU voltage, if the result at the tube is correct. Doesn't address any audio issue. 6.5-6.6V is indeed in spec (6-6.6V), and does not significantly change tube life. It's not design center (virtually NOTHING ever is), but it's not out of spec either. PF86 / EF86 switch: resistor inline to drop voltage for PF86. Another possible place to tweak voltage. Here's another guy (http://www.foxaudioresearch.ca/GothamAudio.htm) who recorded a loss of 0.9v over 25'. I'd agree 100% that two well built cables of same spec should sound identical, but these China cables don't qualify. My take is they're just no good and very low-quality. But what else can you expect for $3/cable?
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Post by ChaseUTB on May 25, 2017 18:58:38 GMT -6
Brian Fox modded my mics! Great knowledgeable guy 🤠
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Post by ChaseUTB on May 25, 2017 19:00:53 GMT -6
I'd have to go back and look, but I recall voltage being correct range. Good point on higher capacity cable, no different from what we consider with any power loom in any situation; 500 rack, console, etc. One could also argue the Chinese cable is 'factory matched' to the PSU voltage, if the result at the tube is correct. Doesn't address any audio issue. 6.5-6.6V is indeed in spec (6-6.6V), and does not significantly change tube life. It's not design center (virtually NOTHING ever is), but it's not out of spec either. PF86 / EF86 switch: resistor inline to drop voltage for PF86. Another possible place to tweak voltage. Here's another guy (http://www.foxaudioresearch.ca/GothamAudio.htm) who recorded a loss of 0.9v over 25'. I'd agree 100% that two well built cables of same spec should sound identical, but these China cables don't qualify. My take is they're just no good and very low-quality. But what else can you expect for $3/cable? Is this only tube mic cables that carry the signal to the power supply? Or both the one from the mic to the supply and the supply to a line in? Does this same effect happen when using FET mics and the 3 pin XLR cables?
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Post by Martin John Butler on May 25, 2017 19:39:50 GMT -6
Here we go again. Cables sound different, cables shouldn't sound different, something must be wrong. If nothing's wrong, then cables just sound different. I've heard differences with some cables, but haven't tried an A-B with mic cables in so many tears, I forget if I heard any difference.
I use Mogami for my mics. Should I bother trying a Gotham or Sommer cable?
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Post by jakeharris on May 26, 2017 18:10:29 GMT -6
Is this only tube mic cables that carry the signal to the power supply? Or both the one from the mic to the supply and the supply to a line in? Does this same effect happen when using FET mics and the 3 pin XLR cables? All this is just about the cable from PSU to mic, carrying power and audio on 7-wires. No idea for FET mics, I've always used GAC-3 and never given it more thought. Not expensive at all if you make your own cables.
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