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Author Topic: AT-853 mod weirdness  (Read 1716 times)

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Offline nulldogmas

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AT-853 mod weirdness
« on: February 10, 2023, 09:53:49 AM »
I bought a set of reputedly low-sensitivity-modded AT-853s here a few years back, though I was never 100% sure whether the mod was working as described. (Sometimes the output seemed on par with my other low-sens 853s bought directly from Sound Professionals, other times louder.)

I just loaned them out to a friend, and he reported back that when run through a battery box (no preamp) the mics are providing 8 dB higher output than when powered by his recorder's 3v plug-in power. Has anyone ever experienced anything like this? Anyone have any idea what could be causing it?

Offline Gutbucket

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Re: AT-853 mod weirdness
« Reply #1 on: February 10, 2023, 10:20:21 AM »
It is not uncommon for sensitivity to increase (along with with max SPL) with increased supply voltage.  I don't know the specifics for the AT853, and the times I've used them they were always powered with PFA's supplying ~9V, but I'm not overly surprised by that.

To determine if the low-sensitivity mod is in place, you can unscrew the cover of the connector and look for resistors, which is where the mod is usually done.  Resistors present = modded.  No resistors = no mod.
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Offline nulldogmas

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Re: AT-853 mod weirdness
« Reply #2 on: February 10, 2023, 12:42:30 PM »

To determine if the low-sensitivity mod is in place, you can unscrew the cover of the connector and look for resistors, which is where the mod is usually done.  Resistors present = modded.  No resistors = no mod.

"Unscrew the cover of the connector" does not compute, but it's a fat plug, so I'm sure resistors were inserted. Whether they're actually resisting anything is the bigger question. (The fact that they're overloading the recorder going Line In at loud shows is an indication they're not.)

Offline Gutbucket

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Re: AT-853 mod weirdness
« Reply #3 on: February 10, 2023, 02:05:41 PM »
You can probably non-invasively determine if the resistor is in the circuit or not without opening things up by measuring with an ohmeter.  I don't know what the value would be indicating its presence or absence though. 
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Offline nulldogmas

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Re: AT-853 mod weirdness
« Reply #4 on: February 10, 2023, 04:47:35 PM »
You can probably non-invasively determine if the resistor is in the circuit or not without opening things up by measuring with an ohmeter.  I don't know what the value would be indicating its presence or absence though.

Yeah, Sound Professionals will take a look and do this for me for $50, so that seems like the simplest solution. Thanks for helping me sleuth it out this far, though!

Offline moondust.and.solitude

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Re: AT-853 mod weirdness
« Reply #5 on: February 11, 2023, 01:40:39 PM »
If the mod you are referring to is the 4.7k mod, then I think it's working correctly by design. If I am not mistaken (and I could be) but didn't Chris Church come up with this mod to run mics using 3volt PIP to achieve lower sensitivity and a higher SPL? It's usually a drop of 8-10db's, so the increase of 8-10dbs when adding more power to the mics sounds to me like it's performing as should.

I'm not the expert like Gutbucket is, but that's my understanding of how the 4.7k mod works.
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Offline morst

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Re: AT-853 mod weirdness
« Reply #6 on: February 11, 2023, 02:36:07 PM »
You can probably non-invasively determine if the resistor is in the circuit or not without opening things up by measuring with an ohmeter.  I don't know what the value would be indicating its presence or absence though.

Yeah, Sound Professionals will take a look and do this for me for $50, so that seems like the simplest solution. Thanks for helping me sleuth it out this far, though!
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Offline nulldogmas

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Re: AT-853 mod weirdness
« Reply #7 on: February 11, 2023, 07:54:52 PM »
If the mod you are referring to is the 4.7k mod, then I think it's working correctly by design. If I am not mistaken (and I could be) but didn't Chris Church come up with this mod to run mics using 3volt PIP to achieve lower sensitivity and a higher SPL? It's usually a drop of 8-10db's, so the increase of 8-10dbs when adding more power to the mics sounds to me like it's performing as should.

The Sound Professionals low-sensitivity version of the AT-853s don't work this way — they provide reduced signal even when powered with a battery box.

In any event, the problem is that these mics are overloading the recorder at high SPLs when run with a battery box, and running them with PIP at high SPLs seems unlikely to go well. So if SP can fix this for me, it's well worth the 50 bucks.

Offline moondust.and.solitude

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Re: AT-853 mod weirdness
« Reply #8 on: February 11, 2023, 09:31:44 PM »
If the mod you are referring to is the 4.7k mod, then I think it's working correctly by design. If I am not mistaken (and I could be) but didn't Chris Church come up with this mod to run mics using 3volt PIP to achieve lower sensitivity and a higher SPL? It's usually a drop of 8-10db's, so the increase of 8-10dbs when adding more power to the mics sounds to me like it's performing as should.

The Sound Professionals low-sensitivity version of the AT-853s don't work this way — they provide reduced signal even when powered with a battery box.

In any event, the problem is that these mics are overloading the recorder at high SPLs when run with a battery box, and running them with PIP at high SPLs seems unlikely to go well. So if SP can fix this for me, it's well worth the 50 bucks.

I see. My bad, I was taking a stab in the dark. Good luck with getting them fixed. Chris at Sound Pro is a stand up guy, so I'm sure he'll fix 'em up right for you.
Mics: Lewitt LCT-040; Naiant X-X Omni's; Audio Technica U853AW's; Sony ECM-166BMP's; Audio Technica AT-853's.
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Recorders: Tascam DR-100mkIII; Tascam DR-05x, Sony PCM-A10.
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Offline DavidPuddy

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Re: AT-853 mod weirdness
« Reply #9 on: February 12, 2023, 06:53:23 PM »
If these are the ones you bought from me, shoot me a PM and I’ll give you the order info
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Offline nulldogmas

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Re: AT-853 mod weirdness
« Reply #10 on: February 13, 2023, 07:27:03 AM »
If these are the ones you bought from me, shoot me a PM and I’ll give you the order info

Thanks, but I think I got these earlier direct from Darktrain. Will PM you to confirm.

 

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