Topic: sp cmc-4/sp cmc-8:what 's the best ?

[Karl]

+T for the name as well  

Also, can you post a pic of this 18v adaption you have done? I am electrically challeneged, really.  I know that aint good for a taper, but its the way I am.  I have the CMC-8s, and  people have been modding the CMC-8s for 48v phantom power, . So 18v shouldnt be a problem.

Actually, that's where battery power and phantom power differ.  Battery power delivers a voltage to only one side of the mic capsule; the other is at ground.  In phantom power, an equal voltage is delivered to both sides.  So, if we applied 48v through battery-style powering (and not phantom) it might damage the mics.

I would post some pics, but I have no digital camera, and not even a scanner.  A little challenging there, sorry!

JK, that sounds like it would work also, having a dual 9v batt box!

[leegeddy]

In phantom power, an equal voltage is delivered to both sides.  So, if we applied 48v through battery-style powering (and not phantom) it might damage the mics.

this is untrue and wrong. phantom power does not apply 48v to both sides of the capsule.

marc

[Karl]

In phantom power, an equal voltage is delivered to both sides.  So, if we applied 48v through battery-style powering (and not phantom) it might damage the mics.

this is untrue and wrong. phantom power does not apply 48v to both sides of the capsule.

marc

What does happen then? 

[kfrinkle]

Makes me want to find a 48 volt battery in the shape of a 9volt and slap that bitch into my battery box.  I am really really interested in this modded battery box that SP did for you though.  My only problem, is that if you spend 10 bucks at SP, you end up spending another 100 to make it all work fucking right.  they have always been nice to me, but I am broke and cant afford the cost of such a modifiication right now. (and i really wont plug in a 48v battery into my battery box, i love my mics too much, perhaps a 12 volt...)

[OOK]

Ok maybe I should have stated it a little differently....The mics were not recieving enough juice from the original battery box....I don't believe the box is passive.  It supplies power via a 9volt batt. to the mics.  What changed when going with the newer box was the mic input went from a single TRS stereo input to dual TRS inputs.  It changed the mics from high impedance to low impedance.  The box is still powered by a 9volt batt.    Its  not passive.  what causes the mics to distort is they are not recieving enough voltage to realize their potential.  Most portable decks with mic inputs supply about 1.5 volt of plug in  power.  I forget what voltage my battery box suplies but I know its more than 1.5vlts.  If I remember correctly I think its around 9vlt acoording to the guys at SP....Don't quote me through its been about 2 years since I talked to them...so yes your right it is the mics.......their just not getting enough juice......if your getting distortion......

[Karl]

Another thought--about a year ago I was messing around with battery box power--and I boosted my battery box up to 18v.  I sat second row and recorded Dream Theater (with the CMC-4's, aka AT853)(loud, loud concert) and I had virtually no distortion problems.  18v battery box power is something I would like to see more people experiment with--it looks promising.  I don't think it will still be the same as phantom power, but for those who still want to be super-stealth and want to avoid distortion with this setup, I think it's prob a good route to try.

You have access to both 9 and 18 Volts bboxes, all else being equal? Then you should make a pair of high SPL recordings using your stereo to demonstrate the difference. I would have expected the benefits to be minor at best and there are numerous disadvantages to going up in voltage. Increased selfnoise being one of them.

Jon

I saved the samples of my testing, but they are at home (I'm at work right now).  Can I attach mp3's to my post?  That's what I'll do if I can. 

The self-noise was a tad higher, but since it's an application for high spl's anyway, that's a non-issue.

[Karl]

Check out these two attacments...

These are SPL tests that I did in my car.  Playback is from an Alpine cd deck, into a PPI 5440 amp, all JL Audio speakers, the sub is a 12" in a bandpass box.  As you'll hear, the difference is more than obvious.  Also, I left two seconds of silence at the beginning of each track so that you can hear the noise floor difference (like I said, very minimal).  The car was turned off, windows rolled up.  Awhile back I measured my car stereo's output at 130+ dB.

Just for records sake, the test was done with AT853 (omni caps) into homemade batt box (18v vs 9v being the variable), into JB3 (no gain adjustments).  Enjoy!

[kfrinkle]

Damn homey, there is a HUGE difference there.  I want one of those.... i wish i had the cash, it would solve alot of my problems...

[Steelcorner27]

Yes you are right 18v makes them performance like night and day...(now for a shamless plug) Infact I have just the thing for you.

http://taperssection.com/index.php?topic=36228.0

Brad

[Brian Skalinder]

Check out these two attacments...

The 18v source is significantly louder than the 9v, which usually translates into "better sounding".  I know, I know...setting precisely the same levels for comps is NOT easy, I've done my share!  Anyway...after adjusting the amplitude and normalizing so they're both roughly the same loudness, I didn't hear much of a difference.  Granted they're MP3s - maybe the WAVs sound significantly different.

Edit to add:  upon further listening, the 18v source appears to have more pronounced and cleaner highs, tighter bass, better detail.  But...dunno if that's from the 18v power or the higher levels at the time of recording.  Hmmm...curious...thanks for the samples!

[Karl]

Check out these two attacments...

The 18v source is significantly louder than the 9v, which usually translates into "better sounding".  I know, I know...setting precisely the same levels for comps is NOT easy, I've done my share!  Anyway...after adjusting the amplitude and normalizing so they're both roughly the same loudness, I didn't hear much of a difference.  Granted they're MP3s - maybe the WAVs sound significantly different.

Edit to add:  upon further listening, the 18v source appears to have more pronounced and cleaner highs, tighter bass, better detail.  But...dunno if that's from the 18v power or the higher levels at the time of recording.  Hmmm...curious...thanks for the samples!

Keep in mind that the recording was an exact A/B comparison (with 9v vs 18v being the ONLY variable)--so the higher levels are a result of 18v!  There is approximately a 3 db difference between the two clips.

Yes, listen to the higher freqencies (cymbals esp).  The bass frequencies are what actually causes the distortion, but you can recognize the effect by listening to what the distortion does to the higher frequencies.

btw, I use LAME mp3 encoding--one of the cleanest mp3 encoders out there.

[kuba]

The CMC-8s overload in high SPL situations as well, FYI.  I was running CMC-8's > SP-SPSB-1 > JB3 for both Manson and Isis recently, and the Manson show had awful bass distortion, even though i had bass rolloff at 195 for that gig.  The Isis show has just a tad bit of high SPL distortion here and there.  Levels on JB3 never came close to overloading.  So be warned, it appears that both CMC-4s and CMC-8s will overload in high SPL situations.

My opinion on your distortion issues:

SP-SPSB-1 roll-off isn't worth damn used with JB3 because the condenser values are calculated against another input impedance (10KOhms, but JB3 has ~~37KOhms(?)). So that it wasn't rolled-off at 195dB, but much lower frequency. Correct me if I'm wrong.