Topic: SP-CMC-4U aka AT 853 trouble with recording

[swordfish]

Hope to get some adivise here...

I have a question about a recording a made earlier today.  A while ago I traded my SP-CMC-8 against SP-CMC-4U.  Today was my posiibilty to test the new mic with the hyper caps I ordered.

Have to say that I had the cable length made shorter about 1 Feet and 10 Inch due the thickness of the cable and the place where I will wear the mic during the stealth recording.

What I recognized is that the CMC 4U is very sensitive.  I couldn't test it because I can't use my stereo at the moment.  Since I never had problems with my CmC-8 I thought I will give it try without testing.  It was outdoor venue and I knew that the sound would be with heavy bass.  But in general very nice and clear.

Due to the to the fact that the mics is very sensitive...I decided not to use one of my preamps.  The lineage is as shown below.

CMC 4 U - --->- SP-SPSB-11 (bass roll off set to 69 Hz) Switch 1,4 to the open position ------Edirol R09-HR line in.

With an preamp I aways set the Edirol at O gain at 40 and control levels with the amp .  Today I had to lower the recording level to 11 but the level meter still showed recording levels between -12 and -6.

As a result a have a very muffled bassy recording...acutally no need to work on it....just for the bin

Anybody has an idea what went wrong?

I am thinking about sending the mic bodies to SP and have em checked.

SF

[fmaderjr]

If the concert was loud and you did not get the low sensitivity mod, that could well be the problem.

Also if your preamp is capable of attenuation (like the Church Audios), you should always use it when using sensitive mics-even for very loud stuff. Then you can leave the HR at unity gain (around 38) and attenuate with the pre if necessary. When you have to turn the level way below unity gain, there is a point where the recording will still be distorted even if the meters aren't going over 0 dB. I've never read what that point is for the HR, but you were so far below unity gain that is what may have happened.

[swordfish]

If the concert was loud and you did not get the low sensitivity mod, that could well be the problem.

Also if your preamp is capable of attenuation (like the Church Audios), you should always use it when using sensitive mics-even for very loud stuff. Then you can leave the HR at unity gain (around 38) and attenuate with the pre if necessary. When you have to turn the level way below unity gain, there is a point where the recording will still be distorted even if the meters aren't going over 0 dB. I've never read what that point is for the HR, but you were so far below unity gain that is what may have happened.

The concert was bassy but not to loud IMO..I should have used my CA 9100 or the Tiny box which I used the night before with the M 10.  But I have to much new stuff and not enough shows to test the equipment. 

I will go the next week to the same venue and test the mic with CA 9100 and the M10...or do you think I should get the 4.7 K mod for the AT 853?? is it that sensitive?

I will get the CA 14 as part of the loan process..hope it gets here in time....

thanks for the fast response...

SF

[fmaderjr]

I will go the next week to the same venue and test the mic with CA 9100 and the M10...or do you think I should get the 4.7 K mod for the AT 853?? is it that sensitive?

If concert is not real loud you may be OK without the mod. Leave the HR at 38-40 if possible and adjust the levels with the ST-9100.

If you will record very loud stuff with them everyone agrees you need the mod. I didn't have much trouble with my unmodded ones, but they didn't sound right when I recorded stuff like Iggy Pop. If you do any stack taping you definitely need the mod as well. In short, its safer to get the mod unless you plan on sticking to using the Church Audio mics for the loud stuff.

[adrianf74]

If the concert was loud and you did not get the low sensitivity mod, that could well be the problem.

Also if your preamp is capable of attenuation (like the Church Audios), you should always use it when using sensitive mics-even for very loud stuff. Then you can leave the HR at unity gain (around 38) and attenuate with the pre if necessary. When you have to turn the level way below unity gain, there is a point where the recording will still be distorted even if the meters aren't going over 0 dB. I've never read what that point is for the HR, but you were so far below unity gain that is what may have happened.

The concert was bassy but not to loud IMO..I should have used my CA 9100 or the Tiny box which I used the night before with the M 10.  But I have to much new stuff and not enough shows to test the equipment. 

I will go the next week to the same venue and test the mic with CA 9100 and the M10...or do you think I should get the 4.7 K mod for the AT 853?? is it that sensitive?

I will get the CA 14 as part of the loan process..hope it gets here in time....

thanks for the fast response...

SF

Hey... I hear your pain.  I had a pair of AT-933's which sometimes did this when it was "overly loud" and I'd end up with a muddy recording.   I've found with AT mics, in general, that when you get a good recording, you get a good one ... when you get a bad recording, it's pretty ugly.

Give Chris' CA-14/c a shot if you can get in the loaner program.  After listening to many shows on DIME (as well as talking to some people here), I bought a pair of CA-14/c's and a pair of CA-14/o's to compliment my CAFS-OMNI.  Keep in mind the loaner pair you'll get had the older windscreen/membrane on it.  The newer one is 20% smaller according to Chris.  I've posted a picture of the 'new' CA-14/C (and o) in the Retail space for Chris' July Sales thread because somebody had asked for a photo.  I'm gonna do a proper one with my DSLR when I have five - maybe tomorrow - and then post those.

If you can run the ST-9100 pre-amp, you're always better to.   I haven't had a chance to run my CA-14's with the Ugly Battery Box yet, however, everything I've read and been told is that you'll get a better recording if you have the pre-amp in line because you can adjust the levels of the mics before the deck.  I've often had to crank my older R09 up to the max (to still not be hitting -6dB). 

Another thing worth mentiong... I think the CA-14/c is a better mic than the CMC-4U or CMC-8.  I had the older AT-933 CMC-8 and I find the clairty of the CA-14 to be better than the Sound Pros mics - but that's just my opinion (and a few others on here). 

[SmokinJoe]

AT853's were originally designed to work with phantom adapters, in a 3 wire configuration.  Frequently people make them a "2 wire configuration" like the CMC-4, because it's handy to make a stereo pair on a single 1/8" jack.  The problem is that's when this is done the mics can't take nearly as loud music before they "brick wall" aka distort.  The fact that you had to turn the gain down on the R09HR tells me it was loud, probably loud enough to be a problem.  It's happened to me, and I wouldn't be surprised it happened to you.  If you open up the wave file in an editor (like Audacity) if all the wave forms look clipped at the top, that probably confirms the suspicion.

Chris Church (aka Church audio) invented a little fix of this sensitivity problem called the "4.7k mod", because he puts a little 4.7k resistor across some connections.  Sound Professionals will uses this fix, calling it the "low sensitivity mod".   I think probably you need that done.  If you have good eyes, a steady hand, and good soldering skills, you can probably do it yourself.  I have a pair that I had done by Chris Church, he does a nice job and it's all hidden inside the 1/8" stereo connector where it plugs into your preamp... he charges about $25 for the work, and because he's in Canada it cost about $22 to get it back to the US in any reasonable amount of time.  Sound Pros would probably do it too.   This drops the sensitivity of the mic by 12dB, and works very well.

[Belexes]

I have the mics, had distortion issues, did the 4.7k mod...no more issues.

[swordfish]

I have the mics, had distortion issues, did the 4.7k mod...no more issues.

Thanks guys for all the answers ----> looks like the 4.7 K mod might be the fix.   

I will get it a try.

SF

[swordfish]

AT853's were originally designed to work with phantom adapters, in a 3 wire configuration.  Frequently people make them a "2 wire configuration" like the CMC-4, because it's handy to make a stereo pair on a single 1/8" jack.  The problem is that's when this is done the mics can't take nearly as loud music before they "brick wall" aka distort.  The fact that you had to turn the gain down on the R09HR tells me it was loud, probably loud enough to be a problem.  It's happened to me, and I wouldn't be surprised it happened to you.  If you open up the wave file in an editor (like Audacity) if all the wave forms look clipped at the top, that probably confirms the suspicion.

Chris Church (aka Church audio) invented a little fix of this sensitivity problem called the "4.7k mod", because he puts a little 4.7k resistor across some connections.  Sound Professionals will uses this fix, calling it the "low sensitivity mod".   I think probably you need that done.  If you have good eyes, a steady hand, and good soldering skills, you can probably do it yourself.  I have a pair that I had done by Chris Church, he does a nice job and it's all hidden inside the 1/8" stereo connector where it plugs into your preamp... he charges about $25 for the work, and because he's in Canada it cost about $22 to get it back to the US in any reasonable amount of time.  Sound Pros would probably do it too.   This drops the sensitivity of the mic by 12dB, and works very well.

Is there a layout/blueprint for the mod available....I learned soldering about 37 years ago and I think I am still able to do it myself.

Thanks,

SF

BTW: PM and I send you my email address.

[SmokinJoe]

The search feature on this forum is your friend.  See illconditioned's response, 2nd post down on this page.
http://taperssection.com/index.php?topic=94582.msg1259961#msg1259961

On your mics as it is, they probably tie the yellow wire to ground.  What you need to do is cut that connection and stick a 4.7k resistor between the yellow wire and ground. 

Some people will advise you to use a special kind of resistor to reduce noise, and they are probably right.  I did a set using cheap ones from Radio shack, and didn't notice any particular noise.  Someone suggested getting a stock cable, like a Y cable for 1/8" stereo to RCA's, cut the RCA's off, and wire the mics to that, and put the resistors at the Y.  That's what I did, because I'm not good enough to fit it all inside a miniplug body.  Then I loaned out the set, someone tripped over the cables and ripped out my connections.  After that I sent them to Chris to get them done right.

[swordfish]

The search feature on this forum is your friend.  See illconditioned's response, 2nd post down on this page.
http://taperssection.com/index.php?topic=94582.msg1259961#msg1259961

On your mics as it is, they probably tie the yellow wire to ground.  What you need to do is cut that connection and stick a 4.7k resistor between the yellow wire and ground. 

Some people will advise you to use a special kind of resistor to reduce noise, and they are probably right.  I did a set using cheap ones from Radio shack, and didn't notice any particular noise.  Someone suggested getting a stock cable, like a Y cable for 1/8" stereo to RCA's, cut the RCA's off, and wire the mics to that, and put the resistors at the Y.  That's what I did, because I'm not good enough to fit it all inside a miniplug body.  Then I loaned out the set, someone tripped over the cables and ripped out my connections.  After that I sent them to Chris to get them done right.

I tested the mics with my PC speakers last night and the recordings were just fine.....Used every BB and Pre and Rec I have.  IMO that proofs that the mics are OK and only need the 4.7 mod. Both of my mics are terminated into a single 1/8 coupling and than I use an extension cable to connect with the other equipment.

Does every mic need a 4.7 resistor or is one resistor enough.  A blueprint/sketch will help a lot.  I hesitate to send the mic to Can or the USA for the mod due to the fact that I have to pay customs for it when it comes back. 

Can't proof that I payed customs for it since I traded the mics with a member off this board. 

SF

[SmokinJoe]

Sorry.  Yes, you need one resistor for each mic, 2 resistors for a pair.