Author Topic: SOUND PROFESSIONALS SP-CMC-2 - Do they need a High SPL Mod? (Read 6823 times)

darktrain · « **on:** May 30, 2008, 03:04:16 PM »

Just got a pair of these for my cousin(getting him started) and i have read conflicting things on the AT831's(SOUND PROFESSIONALS SP-CMC-2 ), do they need the 4.7k high spl mod like the 853's or not with the single mini jack and powered by a battery box?

olyrc · « **Reply #1 on:** May 30, 2008, 04:11:59 PM »

I ran those same mics through a batt box for my first rig and had no problems.

darktrain · « **Reply #2 on:** May 30, 2008, 04:15:03 PM »

They will see most of there duty running smaller rock type shows

nameloc01 · « **Reply #3 on:** May 30, 2008, 04:32:08 PM »

Three wire mics perform best when powered "3 wire". If you already have a battery box (SP) and they are already terminated into a single mini plug, you will run into clipping (at some point) ealier than you should.
"Modding" the mics is definitely cheaper than powering them "3 wire" but the trade off is the performance is not as good.(Spl handling is NOT AS high and the noise/distortion is not lowered in relation to the gain loss) So...decisions..decisions...

darktrain · « **Reply #4 on:** May 30, 2008, 04:44:28 PM »

he is getting a 9 or 12v bb with single 1/8 input so looks like i will just do the 4.7k high spl mod for him on it, if he gets into it like me(it may run in our blood) then he won't have them for long

it will be a steady spiral downward(in the pocketbook that is) toward better sound

nameloc01 · « **Reply #5 on:** May 30, 2008, 04:57:26 PM »

Probably best to not jump in head first right off the bat. I am all too familiar with the "downward spiral".
I used to run a pair a 829s with a SP/BB...I actually only had clipping I think 2 or 3 xs'. But, of course, it happened at the shows I wanted to get done well the most. Seems like that's how it always works.
What's he recording with?

Will_S · « **Reply #6 on:** May 30, 2008, 05:00:27 PM »

Try running them as they are first. The 2wire 831s are less prone to distortion than the 853s.

Regarding gain loss, as wired now the 2-wire AT831s (without the 4.7k mod) offer MORE gain than they would if 3-wire powered. So you'd get the best S/N performance as wired now, if you don't run into distortion problems.

nameloc01 · « **Reply #7 on:** May 30, 2008, 05:05:36 PM »

I said 3 wire provides higher spl handling, and WITH the mod there is gain loss. I think you misread what I wrote.

nameloc01 · « **Reply #8 on:** May 30, 2008, 05:07:23 PM »

Also as I was told when you "mod" the mics and lower the gain(sensitivity),the noise/distortion remains the same, it is not lowered in relation to the gain loss. Hence more noise,less gain.

Will_S · « **Reply #9 on:** May 30, 2008, 05:09:21 PM »

Quote from: nameloc01 on May 30, 2008, 05:05:36 PM

I said 3 wire provides higher spl handling, and WITH the mod there is gain loss. I think you misread what I wrote.

No, I'm just saying there is MORE gain with the mics how they are right now (2 wire, no mod) than if they were converted to 3 wire or 4.7k mod, which are very close in sensitivity with 3 wire being maybe 2 dB more sensitive than 4.7K mod but both being 10+dB less sensitive than straight 2-wire.

So in other words, converting the mics from 2 wire (no 4.7K mod) to 3 wire also causes gain loss. So gain loss is really not an argument in favor of 3 wire power.

Will_S · « **Reply #10 on:** May 30, 2008, 05:10:32 PM »

Quote from: nameloc01 on May 30, 2008, 05:07:23 PM

Also as I was told when you "mod" the mics and lower the gain(sensitivity),the noise/distortion remains the same, it is not lowered in relation to the gain loss. Hence more noise,less gain.

Again, 4.7K mod vs 3 wire is only a trivial gain loss, ~2 dB, so the noise floor change is pretty trivial as well. Especially for earbleedingly loud rock concerts where SPL handling becomes an issue, the noise floor of the mics is moot.

nameloc01 · « **Reply #11 on:** May 30, 2008, 05:20:07 PM »

Still is not the best way to go. The best way is the best way. The real only issue to modify the mics is its more cost effective. Like I said, he probably is best modding them, as he is new and might decide after pull #1 he hates it.

hopefully not.
Not trying to argue, but whenever someone askes about the right way, its my policy to inform them. Same as if someone asked what the best clips for Schoeps mics are,...that would be Schoeps clips. Not to say there aren't other clips that would "work"...same thing.
Again..not trying to argue.

darktrain · « **Reply #12 on:** May 30, 2008, 05:23:19 PM »

I am pointing him in the direction of a h320 or ihp120, they are solid little machines and with the rockbox agc its basically hit record and thats it, don't want to muddle his mind with preamps and gain control yet, i will wait till he has the "fever" to delve into that and more, just like when i started off with the giant squids and mz-r70 to the nbox and mk4's(its all such a blur)

nameloc01 · « **Reply #13 on:** May 30, 2008, 05:26:39 PM »

I hope you fully enjoy watching his complete demise into a full-blown gear slut. lol

Will_S · « **Reply #14 on:** May 30, 2008, 05:31:29 PM »

Agree with you (nameloc01) to a point, but...

Quote from: nameloc01 on May 30, 2008, 05:20:07 PM

The real only issue to modify the mics is its more cost effective.

That's simply not true. Other advantages of modded mics over 3 wire power (especially as provided phantom adapters) are:

1. Smaller package, including the ability to run directly into many recorders without even a battery box.
2. Better battery life (vs adapters, or straight into a recorder vs. with a battery box).
3. Easier compatibility with off-the-shelf mini preamps, which some people choose to use (or are basically required to use for good signal to noise performance on quiet material).

Is that a worthwhile tradeoff against a potential 2dB rise in the noisefloor, that will be inaudible in most circumstances? Maybe not for some people, definitely so for others.

Darktrain, FWIW, I have run 4.7K modded AT853s directly into an iRiver H120 at moderately loud rock shows with no distortion. I think the H320 offers similar plug in power, but I don't know how the 831s would fare run straight in with no BB.

nameloc01 · « **Reply #15 on:** May 30, 2008, 05:43:00 PM »

You're right on those statements,however the fact still remains the best way is 3 wire-technically. As far as stealth-ability...I could easily stealth several phantom boxes,adaptors,recorders ect. So while you are right about the size,some versatility and that stuff, those are more issues based on opinions and preferences not issues based on technical facts. So, ultimately..its each to his or her own..but the facts always need to be made available...and then good decisions get made and everyones happy.

nameloc01 · « **Reply #16 on:** May 30, 2008, 05:48:18 PM »

But as far as the BB,if you mod them.. For another $40.00 or so dollars a BB(SP) should be used (vs straight plug in) it could save potential problems. -Unless you know for a fact the recorders power will be sufficient.

darktrain · « **Reply #17 on:** May 30, 2008, 06:01:46 PM »

i told him to definately get a bb

Church-Audio · « **Reply #18 on:** May 30, 2008, 06:12:21 PM »

Quote from: nameloc01 on May 30, 2008, 05:43:00 PM

You're right on those statements,however the fact still remains the best way is 3 wire-technically. As far as stealth-ability...I could easily stealth several phantom boxes,adaptors,recorders ect. So while you are right about the size,some versatility and that stuff, those are more issues based on opinions and preferences not issues based on technical facts. So, ultimately..its each to his or her own..but the facts always need to be made available...and then good decisions get made and everyones happy.

Actually its a "technical fact" that my 4.7 k mod with a 9 volt power supply functions as well as a 9 volt 3 wire battery box. Any day of the week and you actually end up with 2 extra db of output then you get with a 3 wire battery box alone.

Just wanted to make sure you knew that. Just because AT does not sell them wired with a 3.5 mm plug does not make it so. Also the other advantages over three wire. You can plug your mics into any 3.5 mm plug in power jack and get sound. Something you cant do with out adaptors with 3 wire. And lets face it when you want to stealth who wants to carry around a huge pair of phantom adaptors? and a phantom supply or use big bulky 3 pin mini xlr connectors when they dont have to. 3 pin is fine if you like it that's great but I would never call it "better"

Chris

nameloc01 · « **Reply #19 on:** May 30, 2008, 06:24:34 PM »

What's the max SPL handling capability? (Before tweaking)

nameloc01 · « **Reply #20 on:** May 30, 2008, 06:26:00 PM »

Ps. Those brownies killed. ;p

Church-Audio · « **Reply #21 on:** May 30, 2008, 06:30:16 PM »

Quote from: nameloc01 on May 30, 2008, 06:24:34 PM

What's the max SPL handling capability? (Before tweaking)

The 853 mics I have measured for example measure about 6% distortion at 114db at 1k when wired 2 wire with out any mods. After the mod the THD is 0.05% at 114db at 1k. Three wire is about the same THD is around 0.08% at 114db at 1k.

Chris

Church-Audio · « **Reply #22 on:** May 30, 2008, 06:30:40 PM »

Quote from: nameloc01 on May 30, 2008, 06:26:00 PM

Ps. Those brownies killed. ;p

Dam you!

nameloc01 · « **Reply #23 on:** May 30, 2008, 06:30:55 PM »

Pss. Not really a huge SP fan. And instead of carrying around a mere ps2 and adaptors...I carry *2* boxes,mics,and 2 decks (and numerous blanks)

nameloc01 · « **Reply #24 on:** May 30, 2008, 06:49:15 PM »

Curious..ever spec 853s ran through 8532s ?
If not, you should..I'd be very curious

Church-Audio · « **Reply #25 on:** May 30, 2008, 06:55:46 PM »

Quote from: nameloc01 on May 30, 2008, 06:49:15 PM

Curious..ever spec 853s ran through 8532s ?
If not, you should..I'd be very curious

No I have not but I suspect that the performance of a regular 3 wire battery box would be slightly better due to the fact that there is no transformer in a regular battery box, Or electronics other then passive components.

Sunday Driver · « **Reply #26 on:** May 30, 2008, 08:41:41 PM »

Quote from: Darktrain on May 30, 2008, 03:04:16 PM

Just got a pair of these for my cousin(getting him started) and i have read conflicting things on the AT831's(SOUND PROFESSIONALS SP-CMC-2 ), do they need the 4.7k high spl mod like the 853's or not with the single mini jack and powered by a battery box?

Hi darktrain, these mics are not "bullet proof" in terms of SPL handeling. I did get what I would call severe distortion when running SP-CMC-2 (AT831) > Sound Pro 9 volt battery box > iRiver H120, in an arena with a large band. No bass roll off (16 kHz) was used, and I was standing about 30 feet from a hanging speaker stack. (I can provide samples on request if you want to judge for yourself.) I used them on two other occasions, and did not get this type of sound, but the volume at these shows was much lower.

---

Also, I finally got around to giving the AT8531s "battery packs" a try, with no phantom source behind them. "Very noisy" (hissy) best describes the results, and I was completely unimpressed. I tore one of them open, and the parts inside were really, really cheap. AT spared no expense on the $2 transformer.

Maybe they put better parts in the AT8532, I don't know.

nameloc01 · « **Reply #27 on:** May 30, 2008, 09:02:22 PM »

Well..one of you guys can tear one apart..mine will retain their virginity.

IMO, they sound better (with my U853s) than my ps2-which sounds good in itself- and they can handle A LOT higher volumes...I don't know the exact dbs' but it is quite a bit...and the mics run high with the ps2 alone. I'll call AT and get some details.( I do think I remember what the specs were, but I want to make sure)