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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: BCostigan on January 31, 2003, 03:01:24 PM
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Anyone know how to do this? I have an mp2 and would like to use the ad-20 just as an a/d converter. Seeing that an sbm-1 (modded) is around $500-600 and a used ad-20 can be had for about $200 just curious if anyone can/knows how to disable the pre???
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One "feature" that Denecke offers for the AD-20 is basically a 16db attenuator cable that allows you to pass a line signal to an AD-20. This negates any gain that the AD-20 may introduce. The instructions with my old AD-20 told you to contact the company for more information about this.
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The problem is I want the gain to come from the mp2 not the ad-20...which will be the last thing before my deck.
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can't you simply run the levels very low and keep out most of the gain introuced? I ran a nifty rig at the Phil&ABB show here at Pinke Knob last summer. AKGc1000s>m148>ad/20>D8. I ran the levels extremely low so there would not be much gain introduced. Sounded nice but there was probably some extra gain introduced. But man those were the best c1000's tapes I ever pulled :o
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You may still want to contact Denecke about the attenuator cable option; they do offer it on their website's product page. That is the only way to my knowledge to use the unit as an a/d. The signal would still pass through the preamp stage, but because no gain would be introduced from the AD-20's preamp, its sonic effects would be minimal.
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You may still want to contact Denecke about the attenuator cable option; they do offer it on their website's product page. That is the only way to my knowledge to use the unit as an a/d. The signal would still pass through the preamp stage, but because no gain would be introduced from the AD-20's preamp, its sonic effects would be minimal.
Hi All,
Actually, gain would be introduced from the AD-20. In this scenario, you are reducing the level from the MP-2 through the attenuator in order to avoid clipping the front-end of the AD-20 analog input stage or to avoid excess level on the output.
The minimum gain (from the specs. at www.denecke.com) is +17dB and there is no way of eliminating it. The pads simply reduce level so it won't clip.
As opposed to just padding an input, as we see on some A/D converter designs, this process would entail padding and then running the signal through the pre-amp stage of the AD-20. This is considerably different than having a straight path into the A/D section. For what it is worth, it is very similar to running through the balanced (XLR) inputs of a Tascam DA-P1. By design, switching to "line" level doesn't circumvent the pre-amp, it places a pad of roughly 50dB in the signal path.
Unfortunately, several years ago, Mike Denecke (may he rest in peace) and Greg Hanson were unwilling to share their schematic of the AD-20 so that we could jumper around the pre-amp section. I thought the AD-20 would be a great value AD converter, but the pre-amp was certainly an obstacle for anyone with a good quality outboard pre-amp.
While it is feasible to set up a system to use the AD-20 (or Zefiro In-Box) with the pads, finding a more appropriate ADC would be better. For those without an outboard pre-amp the AD-20 is great as long as your mics have an alternate source of power.
I hope this helps.
Happy Recording Everybody,
Marc