Topic: AT-853 mod weirdness

[nulldogmas]

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?

[Gutbucket]

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.

[nulldogmas]

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.)

[Gutbucket]

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. 

[nulldogmas]

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!

[moondust.and.solitude]

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.

[morst]

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!

For $50 you can buy a multimeter...

[nulldogmas]

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.

[moondust.and.solitude]

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.

[DavidPuddy]

If these are the ones you bought from me, shoot me a PM and I’ll give you the order info

[nulldogmas]

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.

[Derp1]

I have a question pertaining to a similar situation, and a question looking for someone that works on 853's with the 4.7k mod. I have 2 pairs, one from sound professionals that sound just horrid, and one from someone on here that sound great directly into an A-10 but one channel is crackling and popping and could use some love. The question about the ones from sound professionals is whether I run them into the SP battery box or without the wav's are all out of phase or something? The wav forms are all spiking one direction and they just sound like crap. Any insight into whats up with the SP ones or if anyone knows someone that could look at the others Id appreciate it. Thanks in advance.

[nulldogmas]

I have a question pertaining to a similar situation, and a question looking for someone that works on 853's with the 4.7k mod. I have 2 pairs, one from sound professionals that sound just horrid, and one from someone on here that sound great directly into an A-10 but one channel is crackling and popping and could use some love. The question about the ones from sound professionals is whether I run them into the SP battery box or without the wav's are all out of phase or something? The wav forms are all spiking one direction and they just sound like crap. Any insight into whats up with the SP ones or if anyone knows someone that could look at the others Id appreciate it. Thanks in advance.

Can you post images of the waveforms or sound samples or something? Those sound seriously messed up, but hard to say in what way without more detail.

(Btw, since I never reported back on my original issue: Sound Professionals did a great job re-doing my 4.7k mod for $50, and now my mics work great.)

[unidentified]

Based on my own experience, Sound Professionals did not care for how Darktrain had modded the set of these mics that I bought from him.