Topic: need ACM PMD660 waveform opinion

[kgreener]

please see the waveform jpg below.  recorded a blues band last night using two rigs, JW Mod AT4053a > Advanced Concert MOD PMD660 and AT849 > tmod+ UA-5 >JB3 (ran this stereo boundary mic for backup/kicks).  the waveforms on the AT849 > UA-5 look normal to me, whereas the AT4053a > ACM PMD660 look flat and chopped on the top, and kinda maxed out/clipping on the bottom.  this has happened a few times with the 660, even with the -20db mic attenuation engaged, and has appeared even at lower levels. 

I think it's a sign of brickwalling, and the recording still sounds pretty decent.  when played thru soundforge the places that appear to be clipping do not show up as overs    any ideas why this is happening?  am i just running the 660 too dang hot, and do i need to back off a bit?

it was a long night and i'm kinda out of it today, but this is bugging me enough to get this out to you all for your opinions.  thanks in advance for any help you can provide.

Keith

*edited cuz i'm a dumbass.  this is an Oade ACM PMD660 I am referring to.  Thanks for pointing that out Andrew, +t.  Told you I was slow today  

[aberg]

If this is a stock pmd660, I think this is a known issue with recording live music with it. Such is the reason that Doug Oade offers performance upgrades for the pmd660. I plan to buy the advanced concert mod pmd660 once some stuff of mine sells.

[spyder9]

I think you should send this to Doug.  He'll know.  +T for sharing.  I want to buy a 660.  Was a limiter on?

[kgreener]

I think you should send this to Doug.  He'll know.  +T for sharing.  I want to buy a 660.  Was a limiter on?

yeah Spyder, i was planning on asking Doug, thanks +t.  the -20db mic attenuator was engaged, but this unit does not come with a limiter that i know of.  the more i think about this, the more i'm wondering is 1) maybe this is just the way a 660 waveform looks like and 2) i ran my levels too hot on one side and if i hadn't, the waveform would look a little more even, albeit still crewcut flat on the tops and bottoms.  i actually did run clipped peak restoration in soundforge, -3db w/limiter, and everything appeared more uniform, but still flat on the edges.

bottom line, i guess i'm used to seeing more spiky waveforms  

[d5]

I think you should send this to Doug.  He'll know.  +T for sharing.  I want to buy a 660.  Was a limiter on?

yeah Spyder, i was planning on asking Doug, thanks +t.  the -20db mic attenuator was engaged, but this unit does not come with a limiter that i know of.  the more i think about this, the more i'm wondering is 1) maybe this is just the way a 660 waveform looks like and 2) i ran my levels too hot on one side and if i hadn't, the waveform would look a little more even, albeit still crewcut flat on the tops and bottoms.  i actually did run clipped peak restoration in soundforge, -3db w/limiter, and everything appeared more uniform, but still flat on the edges.

bottom line, i guess i'm used to seeing more spiky waveforms   

This looks similar to a brickwalling problem I had with the 660. The differance is with yours it's happening on only one phase. I talked to Doug about this after seeing the waveforms below from a Radiators show. His suggestion was to use a combination of the microphone's attenuation and the 660's -20 db attenuation to get 660 to where the recording level is set as high as possible. So, with my 460's -10 db pad, I have the following cominations; 0 db (no atten), -10 db (mic only), -20 db (660 only) and -30 db (mic's and 660).  The Radiator's show was recorded with 0 db and my recording levels was set fairly low (~ 9 o'clock). Since then, I'm not defaulting to the -20 db attenuation on the 660.

Also, according to Doug, the type of resistence used in the recording level isn't the cleanest and introduces some level of noise. Having the recording level set high reduces the amount of resistence and thereby reduces the amount of noise.

Here are two wave forms from the Radiators show:

[kgreener]

I think you should send this to Doug.  He'll know.  +T for sharing.  I want to buy a 660.  Was a limiter on?

This looks similar to a brickwalling problem I had with the 660. The differance is with yours it's happening on only one phase. I talked to Doug about this after seeing the waveforms below from a Radiators show. His suggestion was to use a combination of the microphone's attenuation and the 660's -20 db attenuation to get 660 to where the recording level is set as high as possible. So, with my 460's -10 db pad, I have the following cominations; 0 db (no atten), -10 db (mic only), -20 db (660 only) and -30 db (mic's and 660).  The Radiator's show was recorded with 0 db and my recording levels was set fairly low (~ 9 o'clock). Since then, I'm not defaulting to the -20 db attenuation on the 660.

Also, according to Doug, the type of resistence used in the recording level isn't the cleanest and introduces some level of noise. Having the recording level set high reduces the amount of resistence and thereby reduces the amount of noise.

thanks d5, +t.  but i'm not really sure what you mean by "Since then (Rads show), I'm not defaulting to the -20 db attenuation on the 660"...I thought you were using the internal attenuator?  anyway, my levels were set around 3 o'clock originally, but i had to back off as volume increased during the show, and i was at around 1 o'clock by the end of the night.  btw, i do have a pair of AT8202 attenuators that i can try, starting with -10db, and then work my way up if I have to, though to be honest i'd rather not have these 4" barrels sticking out the back of the 660...kind of defeats the purpose of having a small rig, but what are ya gonna do...

oh yeah, one thing that's taking some getting used to on the 660 is the dual knob for setting levels.  it's a small dial and is a little tricky setting levels if one side is hotter than the other, especially if you have fat fingers (or a good buzz on ).  i found i have to grab the outside dial with one set of fingertips and the inside dial with my other fingertips and then tweak the levels.  but, i'm sure i'll get used to it.

having said all of this, and as previously reported, this little box sounds friggin' nice.  what an amazing sound coming from such a small box, and for you fellow 16-bit holdouts, it's everything it's reported to be, and more.  and for all of you waiting on the ACM PMD671, if it's anything like this box (which I know it will be), you're gonna have a sweet-sounding all-in-one 24-bit box in your possession.  Doug Oade works his magic once again

if i can figure out how, i'll try to post some samples from the other night for you all to check out.

peace,
Keith

[spyder9]

Keith,

Post a thread on Doug's site on this.  I want to buy one of these.  Granted, they do sound nice from the 1 recording I've heard.  But could they sound better?  If the 660 can still easily brickwall or chop off the wav, then the advertised mod is not doing its job: modified to handle live concert music.  We shouldn't have to attenuate the incoming sound at the microphone or put in a line attenuator.  We should just have to play with the levels at the pre. 

[aberg]

Dan, I agree 100%.

[kgreener]

agreed guys, i'll do this now.  feel free to chime in with your concerns over there as you are doing here, the more I/we can learn about this thing the better.  +t's to ya both.

[spyder9]

agreed guys, i'll do this now.  feel free to chime in with your concerns over there as you are doing here, the more I/we can learn about this thing the better.  +t's to ya both.

Will do.  +T backatcha!  in 12!

[Chuck]

Did you try the built in mic attenuation on the 660? I've heard that Doug is recommending to use that with high output microphones.
I'm not sure how or if that would affect the quality of the sound, but it may help with the brick-walling.


Hmmm... now that I read the thread through, It looks like another problem. Please let us know what Doug says. I just got my 671 and plan to get the ACM mod when the parts are available.

[d5]

i'm not really sure what you mean by "Since then (Rads show), I'm not defaulting to the -20 db attenuation on the 660

ooops, should have been now defaulting to -20 db attenuation on the 660

[kgreener]

i'm not really sure what you mean by "Since then (Rads show), I'm not defaulting to the -20 db attenuation on the 660

ooops, should have been now defaulting to -20 db attenuation on the 660

thanks man.

[kgreener]

* updated to add some 128kbps mp3's from the other night:

source: JW mod AT4053a > ACM PMD660
hypers/DIN, DFC approx. 12ft from stage

http://www.streamload.com/kgreener/EL/12L6Z7BQD3/robertray2005-10-29d1t09.mp3
http://www.streamload.com/kgreener/EL/BXUJBX2O1R/robertray2005-10-29d1t12.mp3

[aberg]

Sounds great!

I'm really looking forward to grabbing one of these. Apparently there's a 2 week delay at Oade's for shipping. Oh well, patience is a virtue I suppose.