Cleanly boosting audio line inputs from Laserdisc and VHS?

[meljr]

Hi. First off, let me say that I could be talking out my butt. I know enough to know how to shoot myself in the foot, while overlooking some basics. My apologies if these questions are dumb.

Now then, I've been capturing some video (tapes and LDs) and some audio (cassettes and vinyl) recently. Right now, I feed the analog audio directly into a Focusrite Scarlett box, via RCA-to-line-in cables. It works but the output is lower than I'd like. As best I can tell, I have the Scarlett capturing the signal as it is, with no artificial boosting or lowering.

For reference, I have some LDs with the same soundtrack on the digital and analog tracks. Comparing them, the analog track is always a few DB lower than the digital track, which I've confirmed via various methods is a straight capture of the digital track.

Is there any way to safely boost the analog signal? I believe I can get +6 dB via Focusrite Control. That might be enough to get the analog and digital tracks at roughly the same level. However, I'm assuming this is undesirable for various reasons, such as boosting hiss.

I've seen some people talking about feeding their line ins into something like a CleanBox Pro and using the balanced outputs. If nothing else, this seems like it would help with the cassettes and vinyl, even if I worry that, no matter what, it's going to boost the hiss and other undesirable sounds to undesirable levels along the way.

Am I shooting in the dark? Is my current setup about as good as it gets for home captures? Any recommendations for boosting, or at least cleaning up, analog inputs that won't cost a fortune?

Thanks!

[dpalomaki]

First choice (and simplest) would be boost the signal in the Focusrite box.

Keep in mind that when you amplify a signal you also amplify the noise in that signal. The signal to noise ratio remains the same (assuming decent amplifiers are used).

You could add a small mixer/amp ahead of the Focusrite if you need more gain. Of course adding gain could push some portion of the audio signal path into clipping if one is not careful.

Often commercial recordings use compression to increase the perceived loudness by making softer passages louder. Noise is managed by using low noise equipment, noise management at the venue, and filtering. A digital audio workstation software such as Audition is a tool for doing this. It can be used to adjust levels, apply compression and provide filtering including noise reduction.

Typical home video recordings had audio automatic gain control to make softer passages louder (and often also bumped up the background noise as well).

Recorded audio levels are driven in part by the capability of the medium and industry standards for that medium. (But for home recordings all bets are off.) Ultimately the level you get at playback will depend on the player used and how it is setup.

FWIW Consumer line level input/output on the RCA jacks is typically lower than professional line levels (e.g., on balanced on XLR) and feeding out put from one to the other can result in low recorded levels or unwanted distortion.

[meljr]

Thanks. That more-or-less tracks with my general understanding of things. It sounds like I don't have many good options, unless the A/D box is somehow lowering the volume without me knowing.

[timtape]

Quote:

Originally Posted by meljr

Hi. First off, let me say that I could be talking out my butt. I know enough to know how to shoot myself in the foot, while overlooking some basics. My apologies if these questions are dumb.

Now then, I've been capturing some video (tapes and LDs) and some audio (cassettes and vinyl) recently. Right now, I feed the analog audio directly into a Focusrite Scarlett box, via RCA-to-line-in cables. It works but the output is lower than I'd like. As best I can tell, I have the Scarlett capturing the signal as it is, with no artificial boosting or lowering.

For reference, I have some LDs with the same soundtrack on the digital and analog tracks. Comparing them, the analog track is always a few DB lower than the digital track, which I've confirmed via various methods is a straight capture of the digital track.

Is there any way to safely boost the analog signal? I believe I can get +6 dB via Focusrite Control. That might be enough to get the analog and digital tracks at roughly the same level. However, I'm assuming this is undesirable for various reasons, such as boosting hiss.

I've seen some people talking about feeding their line ins into something like a CleanBox Pro and using the balanced outputs. If nothing else, this seems like it would help with the cassettes and vinyl, even if I worry that, no matter what, it's going to boost the hiss and other undesirable sounds to undesirable levels along the way.

Am I shooting in the dark? Is my current setup about as good as it gets for home captures? Any recommendations for boosting, or at least cleaning up, analog inputs that won't cost a fortune?

Thanks!

Not sure for what reason you want to raise the levels on your digital recording. Because it is so low that the digital noise floor is audible? Because you want to get the final digital level higher? These are two different reasons or aims.

Similarly merely raising the gain, and "cleaning up" a recording, are two very different things. "cleaning up" is normally more difficult than merely raising the level, and often impossible. If we raise the gain, of course it will also raise the background noise, regardless of whether the source was an analog or digital recording.

Normally there is no need in digitally recording analog audio to reach the peak 0db digital level at any point in the transfer. A peak of 15db below 0db is normally fine. We do this to avoid accidentally overloading or clipping the digital signal. The digital noise floor should normally be well quiet enough.

These sorts of audio issues are probably best addressed on a dedicated audio forum.

[meljr]

Just to be clear, I pointed out the digital thing simply as a reference point. I want to leave digital recordings alone. I just want to make sure I'm not missing something obvious, or even subtle that can help.

For example, the cassettes I've transferred from a decent deck with zero control over the line out gain are -15-16dB max. The other media varies but, so far at least, has tended to be a bit quieter. (Well, some Hi-Fi tapes I have can go upwards of -12-13dB, but anyway....) If that's all I can reasonably do without SW processing, that's fine.

[lordsmurf]

Spend $100 on this Mackie: https://amzn.to/3SdcWTn
Or this Behringer: https://amzn.to/3HCKd5o

It's Amazon. If that doesn't do what you want, just send it back. But 99% odds you're going to keep it.

Don't try to cheap out and buy the $70 Behringer model, it lacks EQ. And a mixer without EQ is just a worthless volume control knob.

I prefer Mackie, having tested both Behringer and Yamaha, and that's the general consensus online too.

I have the discontinued Mackie Tapco line. I bought mine on a whim about 20 years ago, wanting to better pre-process audio for capture. Little did I know that I'd probably chosen one of the best units in the sub-$500 category (ignoring # of I/O ports, focusing only on audio quality). I really lucked out. These actually still resell for way more than I paid, more than the new Amazon units. We all have moments of dumb luck, that's one of mine.

Don't buy used mixers, you save almost nothing, potential problems are vast.

[timtape]

Quote:

Originally Posted by meljr

Just to be clear, I pointed out the digital thing simply as a reference point. I want to leave digital recordings alone. I just want to make sure I'm not missing something obvious, or even subtle that can help.

For example, the cassettes I've transferred from a decent deck with zero control over the line out gain are -15-16dB max. The other media varies but, so far at least, has tended to be a bit quieter. (Well, some Hi-Fi tapes I have can go upwards of -12-13dB, but anyway....) If that's all I can reasonably do without SW processing, that's fine.

I'm not clear on what you are doing with the Scarlett. Is yours like the current model as pictured? The front panel input gain controls on the Scarlett can be adjusted over a wide gain range. Are you saying that with your VCR outputs connected to the front input sockets, even with maximum gain (usually fully clockwise gains) you cannot reach maximum digital level (0dbFS)?

Do you have Auto Gain or Clip Safe switched in?

https://focusrite.com/products/scarlett-2i2

[meljr]

Quote:

Originally Posted by timtape

I'm not clear on what you are doing with the Scarlett. Is yours like the current model as pictured?

I have the 8i6 3rd gen. I feed it the digital track from my LaserDisc player (and will feed it DATs if I ever get a deck, which looks unlikely) and analog line ins from everything else. (For video transfers, I replace the audio from the capture since I don't trust the processing on the capture card for anything other than a guide sync track.) There are four mono line ins on the back on the 8i6. As best I can tell, it just takes the line ins as they are. I just wanted to confirm. The inputs seemed a lower than expected, although that could just be the way things are. (I've been using LDs as a guideline since some of them have the exact same audio on both tracks, just processed differently for obvious reasons.)

Quote:

The front panel input gain controls on the Scarlett can be adjusted over a wide gain range. Are you saying that with your VCR outputs connected to the front input sockets, even with maximum gain (usually fully clockwise gains) you cannot reach maximum digital level (0dbFS)?

Do you have Auto Gain or Clip Safe switched in?

https://focusrite.com/products/scarlett-2i2

I haven't tinkered with the front inputs yet. I may yet do that, or buy the mixer LS mentioned, or both. (I probably should buy the mixer, at least. I have quite a few analog sources and can't keep pulling cables.) I'm probably doing an awful job at explaining what I want. Basically, I'm seeking reassurance that the Scarlett isn't taking what I assume are "as is" line in connections on the back - assuming Focusrite Control is accurately conveying this info - and somehow making them more quiet than they should be.

For example, I've transferred some cassettes and Hi-Fi VHS tapes. They peak at maybe -14dB max, although some peak even lower (with -20-22dB for some analog sources). Digital LD tracks vary wildly but the I've seen some peak at upwards of -7dB. If that's just how it is, and I need to start learning about audio restoration, that's fine. I just want to make sure I'm not botching the actual input process from the start.

Thanks!

[latreche34]

The capture app or the capture device should have a db meter, you should not exceed -10db, Just because modern digital media lock on 0db or clip it doesn't mean you have to follow the trend. For instance most CD's mastered after 2000 are insanely loud to the point it deserved a name "Loudness War", If you listen to a CD from the 90's and compare it to a modern CD it will sound like half quieter. So don't get sucked into that war and use the meter not your ears.

[dpalomaki]

Quote:

...mastered after 2000 are insanely loud to the point it deserved a name "Loudness War",

Brings to mind the days of rock on AM radio. AM range, thus audience, was based on power. 100% modulation resulted in a longer usable listening reach/range than say 25% modulation. Thus AM stations wanted to keep modulation (loudness for AM) as close to 100 as was legal. To do this they used compressors and limiters to limit the dynamic range of the music sand maintain a legal, high modulation signal.

Modern digital VU meters can show near instantaneous levels thus you can see the nominal recommended record levels around -10 to -12 (where 0 is the point of clipping). Or perhaps you see normal level at 0 db and the scale tops at +10 or +12 (e.g., the VU on the AG-1980). In contrast the old analog VU industry standard meters typically peaked at +3 and had a industry standard damping/transient response. They often has a percent scale and 100% corresponded to 0 Above that the scale was red (and for AM radio purposes implied possible over modulation depending on how the system was setup). Meters on consumer gear often did not have the proper damping and transient response - they were more for show.

[latreche34]

Analog is different, Analog tape for example can take over 0dB because its non linearity nature, in other words it acts like a sponge or a dampener. Digital or converting analog to digital is completely a different story, 0dB is the cutt-off hard ceiling, it only takes one bit or sample higher than normal an it clips, that's why one should allow 10dB headroom for those irregularities.

[timtape]

Quote:

Originally Posted by latreche34

Analog is different, Analog tape for example can take over 0dB because its non linearity nature, in other words it acts like a sponge or a dampener...

Well as I recall, the 0 reference point represented a tolerable level of harmonic distortion, often 3%.

The early magnetic tape oxides had poor output, perhaps 15db lower than later high output ones. Professional tape machines could be switched to various magnetic "flux levels" to accomodate tapes of various output capabilities. So even though playback output varied with the tape type, the meter's 0db mark still represented 3% recorded distortion, which was seen as a tolerable compromise between distortion and tape noise.