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Author Topic: How does one pair of mics become out of phase with another pair on same recorder  (Read 1031 times)

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Offline justink

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I ran AKG hypers (Nbob PFA's) + DPA4023's into a Zoom F8 last night.  It wasn't my deck, so I'm not familiar with it much at all.

Both sources sound good on their own but when i went to matrix them, i noticed that one set was inverted from the other.  not sure which was normal and which wasn't.  it was an easy fix in audacity, but how does that happen?

any ideas?

Pic:  DPA on top, AKG on bottom
« Last Edit: May 31, 2018, 10:25:21 PM by justink »
Mics:
DPA 4028 (wide cards)
DPA 4023 (cards)
Earthworks TC25 (omnis) 

Pres and a/d's:
Oade ACM Grace Lunatec V3 (FOR SALE - Make Offer)
bm2p+ Edirol UA-5 (FOR SALE - Make Offer)

Recorders:
Oade CM Edirol R-44
Sony PCM‑M10

Offline jefflester

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Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."
DPA4061 HEB/AT943 -> CA-UGLY -> R-09
Samson C02/Superlux S502/iSK Little Gem -> DR-680MKII
AKG CK63 -> AKG C460B -> DR-680MKII
AKG CK63 -> nBob actives -> Baby NBox -> R-09/DR2d

Offline justink

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Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."

that makes the most sense.  i'm assuming, since DSatz also had the issue with Nbob cables, it's possible that Nick solders the connections differently.

not a big deal at all if you're only using one set of mics, and it's easily fixable in post to do a matrix.
Mics:
DPA 4028 (wide cards)
DPA 4023 (cards)
Earthworks TC25 (omnis) 

Pres and a/d's:
Oade ACM Grace Lunatec V3 (FOR SALE - Make Offer)
bm2p+ Edirol UA-5 (FOR SALE - Make Offer)

Recorders:
Oade CM Edirol R-44
Sony PCM‑M10

Offline heathen

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The F8 has the ability to change phase of specific channels, so it's possible that's the culprit.  Since it's not your deck maybe it was already set with phase inverted on some channels for whatever reason.
Mics: Core Sound TetraMic | AT4031s | AT AE5100s | AT853s (C/SC) | Line Audio CM3s | DPA 4061s | CA-14 omnis | Studio Projects CS5
Pre: CA9200
Decks: Zoom F8 | Roland R-05 | Tascam DR-2d

Offline justink

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The F8 has the ability to change phase of specific channels, so it's possible that's the culprit.  Since it's not your deck maybe it was already set with phase inverted on some channels for whatever reason.

i didn't know that.  good info!
Mics:
DPA 4028 (wide cards)
DPA 4023 (cards)
Earthworks TC25 (omnis) 

Pres and a/d's:
Oade ACM Grace Lunatec V3 (FOR SALE - Make Offer)
bm2p+ Edirol UA-5 (FOR SALE - Make Offer)

Recorders:
Oade CM Edirol R-44
Sony PCM‑M10

Offline capnhook

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Phase doesn't equal polarity.  What you are doing is flipping polarity, not changing phase.

Just like a 4-mic mix is not a matrix. It is a 4-mic mix.

A matrix involves a SBD feed, and AUD feed.
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BSCS-L->JB-mod [NAK CM-300 (CP-3) and/or (CP-1)]->LSD2->CA CAFS-Omni->Sony ECM-907**Apogee MiniMe Rev. C->CA Ugly II->**Edirol OCM R-44->Tascam DR-22WL->Sony TCD-D8


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Offline Gordon

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Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."

that makes the most sense.  i'm assuming, since DSatz also had the issue with Nbob cables, it's possible that Nick solders the connections differently.

not a big deal at all if you're only using one set of mics, and it's easily fixable in post to do a matrix.

Dsatz didn't have the issue he just chimed in on my thread.  We came to conclusion that JBell's pfa were wired incorrectly thus the issue.   You should be able to easily replicate it at home if it is fact the cables or pfa's.
Neumann ak40 > Nick mod lc3 > Naiant PFA or km140 > Sound Devices MixPre-6

https://archive.org/details/fav-gordonlw

Offline jbell

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After further investigating my PFA wasn't wired incorrectly!!  Schoeps KCY PFA's which is what I was using are wired noninverting to yield positive polarity with schoeps caps.  Using it with Microtech Gefell M20 caps and a Nbob KCY for Gefell's it was a negative polarity so I had the PFA changed to inverting to fix the problem.  I have a backup pfa that I need to test to prove this, but after looking at old recordings when I ran schoeps I'm almost positive this was the problem.  My M20 caps must be grounded different than schoeps caps I previously ran. 

Justin my hunch is your akg's have the same issue.   

Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."

that makes the most sense.  i'm assuming, since DSatz also had the issue with Nbob cables, it's possible that Nick solders the connections differently.

not a big deal at all if you're only using one set of mics, and it's easily fixable in post to do a matrix.

Dsatz didn't have the issue he just chimed in on my thread.  We came to conclusion that JBell's pfa were wired incorrectly thus the issue.   You should be able to easily replicate it at home if it is fact the cables or pfa's.
« Last Edit: June 01, 2018, 04:13:25 PM by jbell »
Microtech Gefell M20's> Nbob KCY> Naiant PFA(60V)> Sound Devices Mixpre-6

Offline justink

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After further investigating my PFA wasn't wired incorrectly!!  Schoeps KCY PFA's which is what I was using are wired noninverting to yield positive polarity with schoeps caps.  Using it with Microtech Gefell M20 caps and a Nbob KCY for Gefell's it was a negative polarity so I had the PFA changed to inverting to fix the problem.  I have a backup pfa that I need to test to prove this, but after looking at old recordings when I ran schoeps I'm almost positive this was the problem.  My M20 caps must be grounded different than schoeps caps I previously ran. 

Justin my hunch is your akg's have the same issue.   

Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."

that makes the most sense.  i'm assuming, since DSatz also had the issue with Nbob cables, it's possible that Nick solders the connections differently.

not a big deal at all if you're only using one set of mics, and it's easily fixable in post to do a matrix.

Dsatz didn't have the issue he just chimed in on my thread.  We came to conclusion that JBell's pfa were wired incorrectly thus the issue.   You should be able to easily replicate it at home if it is fact the cables or pfa's.

so, to clarify... it's possible that the PFA's are wired opposite to the AKG caps? 

because I guess that makes sense.  i'm not very knowledgeable on the subject (why i created the thread).  That said, i guess there isn't really anything "wrong".  it's just a matter of making sure the polarity is playing well with another set of mics when making a mix.
Mics:
DPA 4028 (wide cards)
DPA 4023 (cards)
Earthworks TC25 (omnis) 

Pres and a/d's:
Oade ACM Grace Lunatec V3 (FOR SALE - Make Offer)
bm2p+ Edirol UA-5 (FOR SALE - Make Offer)

Recorders:
Oade CM Edirol R-44
Sony PCM‑M10

Offline jbell

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You generally want positive polarity, but it is easy to fix that in the post.  I went ahead and had my PFA's fixed so I don't have to worry about flipping it in post production. 

After further investigating my PFA wasn't wired incorrectly!!  Schoeps KCY PFA's which is what I was using are wired noninverting to yield positive polarity with schoeps caps.  Using it with Microtech Gefell M20 caps and a Nbob KCY for Gefell's it was a negative polarity so I had the PFA changed to inverting to fix the problem.  I have a backup pfa that I need to test to prove this, but after looking at old recordings when I ran schoeps I'm almost positive this was the problem.  My M20 caps must be grounded different than schoeps caps I previously ran. 

Justin my hunch is your akg's have the same issue.   

Recent discussion on same topic:
https://taperssection.com/index.php?topic=186061

DSatz said:
"Microphone manufacturers are free to ground either side of their capsules, and to apply a positive or a negative charge, as long as in the end, the output of their amplifier has the correct signal polarity."

that makes the most sense.  i'm assuming, since DSatz also had the issue with Nbob cables, it's possible that Nick solders the connections differently.

not a big deal at all if you're only using one set of mics, and it's easily fixable in post to do a matrix.

Dsatz didn't have the issue he just chimed in on my thread.  We came to conclusion that JBell's pfa were wired incorrectly thus the issue.   You should be able to easily replicate it at home if it is fact the cables or pfa's.

so, to clarify... it's possible that the PFA's are wired opposite to the AKG caps? 

because I guess that makes sense.  i'm not very knowledgeable on the subject (why i created the thread).  That said, i guess there isn't really anything "wrong".  it's just a matter of making sure the polarity is playing well with another set of mics when making a mix.
Microtech Gefell M20's> Nbob KCY> Naiant PFA(60V)> Sound Devices Mixpre-6

 

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