Topic: JB3 and Bass distortion

[whssy]

Don't recall seeing this anywhere else...

2 of us recorded the White Stripes gig in Copenhagen the other evening, using JB3s but different mics (AT831s and OKM-IIRs). But both of us ended up with similar distortion in the bottom end that only manifests itself in headphone playback (yes we did try different headsets aswell), even though the settings were miles away from the clipping zone. I am now wondering if this could be something to do with the A/D converters that people seem to be unhappy with. Both of us have previously taped stuff with no problems and this is a show-specific problem. The warm-up band at the same venue recorded fine.

Any ideas as to what the problem might be?

[Evil Taper]

it's the mics>power combo not the JB3.  what you've encountered is an spl overload on your gear that can only be avoided by switching to a phantom power solution or to mics with higher handling.  the adc is just the means in which the digital signal is turned from analog to digital and doesn't cause distortion.  basically adc just adds more resolution and definition to your recording, not higher spl handling.  for $200 you shoudln't really be expecting mic solutions that will never take a dump on you, you get what you pay for.  search around the forums for other stealth options that will solve this problem.  The ps2>ad20 solution will be the cheapest but if you're spending the cash you might as well upgrade to an entirely different rig anyway.

mics>ps-2>ad-20>jb3
dpa 4061>power>recorder
good cards>actives>power>recorder

[zhianosatch]

evil, you have really made a taping turnaround! make sure you catch ministry this spring, yeah?

[tchoub]

I do not own AT831 so I can't comment on those but... did you use the A3 with the OKMIIR ? if so, did you use the -20dB pad ?
I found that, with OKM, distortion was not caused by an overload of the mics themselves but rather by the A3.

[kfrinkle]

its defnitely a power issue together with what goes into the JB3....  People run CMC-8 > SP Bat box into an M1 and get no distortion... run the same rig except CMC-8 > SP Bat box > JB3 and you get fucked up the ass with distortion... it annoys the piss outta me, as I will never buy a dat recorder...  Shit i cant buy any gear at the moment... I sure hope I run into some cash before Tool and Ministry tours...

[Humbug]

Don't recall seeing this anywhere else...

2 of us recorded the White Stripes gig in Copenhagen the other evening, using JB3s but different mics (AT831s and OKM-IIRs).

Just out of interest, where were you located? Was the (bass in particular) sound painfully loud / distorted to your ears?

[whssy]

We considered that our location might be the problem. But we stood in the same position for the Raveonettes, and had no distortion problems. The bass was not painfully loud - in fact it was beautifully clear and resonant, but the vibrations went through the floor and up your legs to the bottom of your belly. We had to stand in front of the PA stack - as there was too much background noise (singers-along, clappers, drunks) everywhere else.

Interesting to note is that a taper stood 3 meters behind me, who recorded into a standard MD deck, had none of these bass problems. So it is starting to sound like a JB 3 issue.

[whssy]

I do not own AT831 so I can't comment on those but... did you use the A3 with the OKMIIR ? if so, did you use the -20dB pad ?
I found that, with OKM, distortion was not caused by an overload of the mics themselves but rather by the A3.

I used the A3 - but not the -20db function. Or the roll-off.

[ethan]

Check the output impedance on the mics and the input impedence specs on the JB3...an impedance mismatch is manifested as a lowend distortion. As a rule of thum your ouput impedance of the mics must be *lower* than the input load impedance.

Also try transfering the show and listening on somthing else....headphone preamps in portable devices are usually substandard and can't be trusted to eveluate recording quality.

-e

[zhianosatch]

wait, whoa, i'm not alone over here? PM sent!!!

[zhianosatch]

and maybe i could explain the problem you had in more detail without having to use a keyboard.

[zowie]

But both of us ended up with similar distortion in the bottom end that only manifests itself in headphone playback (yes we did try different headsets aswell),

Wait a minute.  You mean it's not a problem with other modes of playback?  If that's what you're saying, there's no problem with the mics or the A/D, you're just overdriving the headphone amp.

[ethan]

Check the output impedance on the mics and the input impedence specs on the JB3...an impedance mismatch is manifested as a lowend distortion. As a rule of thum your ouput impedance of the mics must be *lower* than the input load impedance.

Also try transfering the show and listening on somthing else....headphone preamps in portable devices are usually substandard and can't be trusted to eveluate recording quality.

-e

This is interesting. Is this why I had bass distortion on a recent line in show on the JB3 when Ive run in louder environments without distortion when using line in on my M1?

It could be but it also could be that the analog front end of the M1 is just better.

Sony's have a very large line-in input impedance ~50KOhm. What is the load impedance of line in for the JB3? What's important is the match of the output impedance infront (pre or powersupply) and the input (or load) impedance of the recorder.  output of whatever is in front (pre or powersuply) must not exceed the input load impedance of what's behind (recorder).

[whssy]

Check the output impedance on the mics and the input impedence specs on the JB3...an impedance mismatch is manifested as a lowend distortion. As a rule of thum your ouput impedance of the mics must be *lower* than the input load impedance.

Also try transfering the show and listening on somthing else....headphone preamps in portable devices are usually substandard and can't be trusted to eveluate recording quality.

-e

Re impedance - other recordings have been fine.

Re listening on something else - tried that, and it's better but still present. Best results were with my hi fi amplifier of course. Even played out of my computer it's really bad.

[Elana]

I've had major bass distortion on most of my recent (which is like 2) stealth tapes with the AT853's > Batt Box > JB3.  I occasionally had some distortion when I ran MD, but never this much.  Any clues?