Topic: Bad Recording (AT943's > Church Preamp > iRiver H100)

[cgrooves]

Is there a "no gain" or unity gain setting on the Iriver Line In...? If so - thats where you should be - It sounds like you are adding an additional 20db to your pre's signal - and likely overloading the Iriver Line Input. Try setting it to 0db and see if it still passes signal...(Im sure others more familiar with the device will chime in)

Not only is there a 0 gain setting, but you can even use a 'negative gain' setting (I'm assuming it actually attenuates).  If you were wanting to use the rockbox 'AGC Safety' feature, however, you would need to use a little gain on the iRiver so that it would 'bump down' your gain setting just enough that it doesn't clip.

[Roving Sign]

It may not appeared to be clipping - but if you had properly gained recorder to compare it with, you would see the subtle difference in the way the levels move...generally, meters will lack the proper "bounce" - visually speaking...

[Roving Sign]

Is there a "no gain" or unity gain setting on the Iriver Line In...? If so - thats where you should be - It sounds like you are adding an additional 20db to your pre's signal - and likely overloading the Iriver Line Input. Try setting it to 0db and see if it still passes signal...(Im sure others more familiar with the device will chime in)

Not only is there a 0 gain setting, but you can even use a 'negative gain' setting (I'm assuming it actually attenuates).  If you were wanting to use the rockbox 'AGC Safety' feature, however, you would need to use a little gain on the iRiver so that it would 'bump down' your gain setting just enough that it doesn't clip.

So you have to actually add gain to activate this feature? Is that by design? Why wouldn't it work into the negative gain range?

[cgrooves]

So you have to actually add gain to activate this feature? Is that by design? Why wouldn't it work into the negative gain range?

I'm not sure if you have to add gain in order to use the 'AGC Safety' feature.  In theory, I guess you could set the gain at 0 with the 'AGC Safety' feature enabled, and it would bump down to a negative gain setting to prevent clipping if you had the level on the pre too hot.

[Roving Sign]

So you have to actually add gain to activate this feature? Is that by design? Why wouldn't it work into the negative gain range?

I'm not sure if you have to add gain in order to use the 'AGC Safety' feature.  In theory, I guess you could set the gain at 0 with the 'AGC Safety' feature enabled, and it would bump down to a negative gain setting to prevent clipping if you had the level on the pre too hot.

I cant see the need to add gain (at the recorder) AT ALL when using an external pre like CA9100...unless you are recording hummingbirds or something...

[Church-Audio]

I recorded Rush a few nights ago. I was way off to the left, and there was a fair amount of wind. So, I didn't expect stellar results, especially with cards. However, I am more disappointed with the results than I expected. There is a lot of what appears to be brickwalling. This is the loudest show I've recorded with the iRiver/Church combo. I was rushed getting setup (*really* slow security at the venue entrance), and when I started recording the level came on at +20, and I had the preamp up about 1/3 to 1/2 of the way or so. It did not appear to be clipping, so I left the levels alone (plus, I had the Rockbox AGC on). The result definitely sounds like the brickwalling I used to get way back when on my old MD recorder prior to going battery-box/line-in.

There's a lot of distortion, especially on the kick drum. I've recorded plenty of loud rock shows with my old D7/battery box but am new to using a pre and balancing the gain between the pre and the recorder. Is it possible that the pre was too high and sent a distorted signal to the recorder? I had a new battery in the pre, so rule that out....

Here is a sample:

http://home.grandecom.net/~myersfamily/Snippets/rush_sample%201.mp3

Any suggestions?

Any input is appreciated!

Ok.. I analyzed this again and most of the distortion is happening at the low end of the spectrum this would seem to indicated I was wrong with my first statement that it was AGC, not saying it could not have been the AGC pumping.. But there is very little distortion in the top end this suggest that its not my preamp rather its the mics overloading from too much low frequency.. These mics have a high tolerance for SPL at least all the mics I have measured. You might want to consider my 4.7k mod in to your mics... I can make you up a cable with the mod in it so when your recording quiet stuff the mod can be (taken out) and when your recording loud stuff you can run the mod in line with your mics. I will do this at cost.. no mark up for labour I am sure this will solve the problem..

Chris

[cgrooves]

I cant see the need to add gain (at the recorder) AT ALL when using an external pre like CA9100...unless you are recording hummingbirds or something...

I agree completely.  Espescially if the 'AGC Safety' feature is still functional when the iRiver gain is set to 0 (Petur or home testing could verify this).  I would assume that the gain provided by Chris' pre is cleaner than the gain provided by the iRiver pre.

[Church-Audio]

If AGC worked there would be a lot of sound engineers out of a job.. It does not because it can not react fast enough to catch real transient spikes and it does not have "look ahead" unlike real top end compressors costing $1000's even with look ahead on the high end compressor limiters most sound engineers prefer to set the attack and release and threshold manually. I would never EVER use AGC for any recording.. It simply can not work when your very close to the threshold of the AGC it self.

[cgrooves]

Ok.. I analyzed this again and most of the distortion is happening at the low end of the spectrum this would seem to indicated I was wrong with my first statement that it was AGC, not saying it could not have been the AGC pumping.. But there is very little distortion in the top end this suggest that its not my preamp rather its the mics overloading from too much low frequency.. These mics have a high tolerance for SPL at least all the mics I have measured. You might want to consider my 4.7k mod in to your mics... I can make you up a cable with the mod in it so when your recording quiet stuff the mod can be (taken out) and when your recording loud stuff you can run the mod in line with your mics. I will do this at cost.. no mark up for labour I am sure this will solve the problem.

Chris

Sounds like you solved the problem, Chris.  +T

If AGC worked there would be a lot of sound engineers out of a job.. It does not because it can not react fast enough to catch real transient spikes and it does not have "look ahead" unlike real top end compressors costing $1000's even with look ahead on the high end compressor limiters most sound engineers prefer to set the attack and release and threshold manually. I would never EVER use AGC for any recording.. It simply can not work when your very close to the threshold of the AGC it self.

As Petur eluded to earlier:  It apears that you are referring to 'typical' AGC, and not the 'AGC Safety' feature of rockbox.  I assume that even with 'AGC Safety' enabled it is possible to have a short section of clipping while the reduction in gain is being made internally.  The amount of clipping would be increased or decresed, depending on the sensitivity setting being used.

[Roving Sign]

It sounds like the Rockbox AGC:

1 - Only lowers the gain.

2 - Does automatically...what you might do yourself...sort of...

I still favor controlling levels at the pre...not the recorder...

seems like it would be too easy to activate the AGC by accident or random PA noise - and then have the rest of the recording too low.

[Javier Cinakowski]

seems like it would be too easy to activate the AGC by accident or random PA noise - and then have the rest of the recording too low.

Just set the clip time higher.  The AGC won't kick in on short random noises.   

Like Mr. Church I am not a fan of AGC in general.   The rockbox AGC "safety" is an exception...

[cgrooves]

The ONLY time that I would use the AGC Safety feature would be if I was in an 'unopen' environment, and I did not want to appear to be checking / adjusting levels.  If I'm in an open setting, it's all in my hands.

[nihilistic0]

This is what my tool recording with AT853's sounded like

SPL for the bass was just way too high, overloading the mics

[Alchemy]

So this thread brings up an interesting question. The whole purpose of "three wire powering" is to make use of all three wires coming off of those AT's: the grounder, a "red" wire for each mic, and the "yellow" (or white) power cable. In two wire configurations, the grounder is shorted out to the "yellow" (or white) power cable. I'm curious then what is going on inside the CA "three wire preamp". If one of the pins is shorted out under this set-up inside the pre (like with the CA cards), the AT mics and that pre are the same as running a two wire config, except now you have interlocking connectors.

[prof_peabody]

So this thread brings up an interesting question. The whole purpose of "three wire powering" is to make use of all three wires coming off of those AT's: the grounder, a "red" wire for each mic, and the "yellow" (or white) power cable. In two wire configurations, the grounder is shorted out to the "yellow" (or white) power cable. I'm curious then what is going on inside the CA "three wire preamp". If one of the pins is shorted out under this set-up inside the pre (like with the CA cards), the AT mics and that pre are the same as running a two wire config, except now you have interlocking connectors.

Search for 3-wire on ts.com.   There was a lengthly thread that even had schematics.  I think it was in the preamp and powering subforum.