Dcart for increasing Gain

[James]

I will try to explain my situation. I hope it is clear. When recording sound files from my turntable, LP's, 78's etc. I am unable to adjust my input volume on my computer to a level high enough for proper recording. Now, on my Owl 1 unit, I have a -20db switch which does help with 78's, but for LP's, I am at a loss. (Actually, using it with my 78's seems dicey but I have not noticed any distortion of the sound files.) The slider on my soundcard program is at its highest level but I still am under recording the file. I have tried to understand how to improve this but have had no luck. I have no problems with CD's or other formats. With Dcart, can I increase the gain on the recorded file, all the while watching some sort of meters or other form of sound measurement, to increase the sound level to its appropriate level? Thanks!

[Craig Maier]

Re: Dcart for increasing Gain

Your sound card does not have the required sensitivity to be compatible with the Owl 1 as it stands. There is an internal set of voltage dividers
which would have to be modified in ratio to increase the gain appropriately. Another suggestion would be to insert another wideband audio pre-amp between the Owl 1 and the soundcard. Lastly, there are sound cards available with higher input gain values, or you might consider trying the Mic input on the sound card rather than the line input.

The most important thing you seem to have missed, however. The Owl 1 is not capable of stereo reproduction of LP's. It takes the input, sums it together, feeds it through a single RIAA eq amplifer, and then sends that signal out to both channels. The Owl 2 fixes that problem. It is truely stereo.

[DougMac]

Re: Dcart for increasing Gain

Although it wasn't metioned as a solution, this may be an opportunity to discuss the costs of using the gain normalize feature of DC Art. I'll state my understanding and invite others more knowledgeable, especially Craig to correct me if my assumption is wrong. Gain normalize is a very useful tool and I routinely use it to help assure consistency in the CD's I create from my 78's. When I bought a new sound card, I too found myself unable to supply a signal with enough gain. At best, I was still around -10db. I used gain normalize to correct. My son pointed out that I no longer had a 16 bit dynamic range, that by under-recording I was effectively reducing the file's bit depth. If it worked out that the file is 12 bits, the gain normalize only shifts the bits - the file is still 12 bits. From a practical standpoint, especially with 78's, I doubt it makes much difference. I still decided to add a small Behringer mixer in the signal path to give me the needed gain boost. I've been very pleased with the results. I'm looking forward to the OWL 2's release. I hope I'll have saved enough pennies by then.

[Rick]

Re: Dcart for increasing Gain

Your son is basically correct, although increasing the gain is not the culprit. When you record at less than maximum amplitude you are not using all the bits. You loose 1 bit every 6dB away from 0dB your maximum level is. So your -10dB recording is probably more like a 14 bit recording.

Increasing the gain (normalizing) will not reduce this any further, assumming you are not clipping in the first place. It will of course bring up the noise floor. Decreasing the gain will throw away bits.

Rick Carlson

[Beautman]

Re: Dcart for increasing Gain

Is it fair, then, to infer that if one can not get enough input gain to record near 0db, that one can compensate for the lower s/n ratio by sampling at a deeper bit rate (i.e., 20 instead of 16)?

[This message has been edited by Beautman (edited 04-11-2001).]

[Rick]

Re: Dcart for increasing Gain

That is correct assumming that the sound card has an sufficiently high signal to noise ratio so you actually get those extra bits. Most of the good cards do spec 90 or 100dB S/N ratios, so loosing 10dB off the top will not matter that much.

Rick