Dropouts when recording improvements

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MrRecordMan
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Joined: Mon Oct 12, 2020 11:47 pm
Operating System: macOS 10.14 Mojave

Dropouts when recording improvements

Post by MrRecordMan » Tue Oct 13, 2020 12:02 am

Howdy
Long time Audacity user. Currently using version 2.4.2 on an old Mojave machine strictly for ripping vinyl

Very occasionally I get what seems like single buffer dropouts, and I'm trying to improve that.

My setup is...
Input: Turntable -> Rane 70 mixer -> USB to mac
Output: mac USB -> SSL 2+ interface -> speakers

I've tried most everything I could think of.
- I'm not running any other programs
- I've got audacity graphics at lowest settings (ie only updating meters 3x / second)
- I've set the buffer in audacity to an extreme setting, 6000 ms, but this doesn't make any difference. I say this because when I put the needle on the record, there is NOT a 6000ms delay
- Recording format is just at 16 bit
- The RANE is hard-set to 48k, so I've tried setting my audacity project to 48k, no difference, still get the drop out occasionally

I do have software playthrough on because I need to listen to the rip to make sure there are no glitches.

Does anyone have any suggestions?
Would disabling the software playthrough make a huge difference? I'm open to that if there is another way I can monitor what is coming in, ideally via the computer. I'd rather not bypass the computer for monitoring, I still need to listen for glitches.

Thanks for any tips yall have - I'm mostly curious why the 'buffer size' setting seems to have no effect.

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Tue Oct 13, 2020 2:07 am

What's the machine and how old is it? When was the First Birthday?
Output: mac USB -> SSL 2+ interface -> speakers
Can you listen without using a USB service?

Do you have a spinning metal hard drive or Solid State Drive?

Do you have an iCloud connection or any internet connection while you're transferring work?
but this doesn't make any difference.
As I've posted in other messages, it helps us if you can make it worse. Any change you can force, either direction, is valuable to know.

Koz

MrRecordMan
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Joined: Mon Oct 12, 2020 11:47 pm
Operating System: macOS 10.14 Mojave

Re: Dropouts when recording improvements

Post by MrRecordMan » Tue Oct 13, 2020 8:01 pm

Thanks a lot for the reply, I really appreciate it.

The machine is admittedly old, late 2008 MacBook. Its a champ though, when I run my DJ software it handles multi-channel input decoding and output rendering just fine. I assumed 2-channel input would be fine.
I do have internet active, maybe I should disable wifi during ripping? I had tried disabling any network activity on the machine but I could have missed something.

I've not actively tried to make it worse, but that is such a good suggestion though, thanks for putting that thought in my head.

The thing is none of my changes seem to have any effect, better or worse. The buffer size in audacity not seeming to matter is a really big point of confusion for me. Also, Audacity's drop out detection doesn't fire with these particular dropouts (I have been able to trigger that in other ways), makes me think it could be the transmitting hardware in that case?

Other things I've tried, hiding the audacity window, zooming out very far on audacity waveform, zooming in to the beginning so it doesn't have to draw the waveform.

I'll try disabling internet completely and see how far that gets me, this is a really tough one to track down.

I appreciate any further insight. Thank yall :mrgreen:

MrRecordMan
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Joined: Mon Oct 12, 2020 11:47 pm
Operating System: macOS 10.14 Mojave

Re: Dropouts when recording improvements

Post by MrRecordMan » Tue Oct 13, 2020 8:45 pm

Oh forgot to mention - solid state drive, brand new. Max ram (8gb), also brand new.
And it's technically a Macbook Pro.

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Tue Oct 13, 2020 8:47 pm

Sorry for the multi-replies, I can't figure out how to edit a post.

I can listen without USB just via the mixer and playback is perfect.

Also, I have wifi disabled, I'm ripping right now, and I got a glitch. So it's probably not wifi related.

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Tue Oct 13, 2020 10:02 pm

I can't figure out how to edit a post.
Do Not edit your posts. Edited posts—reading backwards—are impossible to follow.

I need to go back and read that again.

Koz

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Tue Oct 13, 2020 10:08 pm

solid state drive, brand new.
So you've been messing around inside your Mac? Did you take a vacuum and soft, clean paintbrush to your fans and vent channels? Keyboard?

Do the glitches occur in exactly the same time every time you play the work? Can you find the damage by zooming?

It's not that unusual for the playback service to cause problems and the show is fine. In that case the damage may wander around.

Koz

MrRecordMan
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Re: Dropouts when recording improvements

Post by MrRecordMan » Tue Oct 13, 2020 11:04 pm

Oh yea I have definitely been in there messing around. This is not my first refurb. I did thoroughly clean it out when I was doing the replacements.

The glitches do NOT occur at the same time. Usually what I do i when I catch it, I just restart the entire side. 90% of the time I will be able to get through it on the second try. Zooming in on the waveform is how I am sure the error is on write, because there is a very small section of pure silence. I haven't measure it precisely to determine if it is some expected number like 128/512 etc...

This again begs my question - at what point does Audacity's 'buffer size' come into play? Like I said, I have it set to 6000ms but playback is almost instantaneous...definitely not 6 seconds behind. If anybody wants to go on that tangent, what exactly does 'buffer size' do in Audacity if its not input and its not output?

Now a small update, tell me if I'm crazy here... but I think I just noticed the glitch occurring just as my AC unit cut off. Now they are not on the same circuit, AC is dedicated as expected, but definitely in the same house and this room is close to the unit.
I will definitely do some science to try and prove this is related, but it would make sense to me.

If it is a power problem, what would be a good solution? I'm running off a standard surge protector right now, I could do something like a rack power conditioner or something I'm just learning about called an 'uninterruptible power supply'. Would either be better or worse? The rack units are designed for audio components and the UPS units seem to be designed for computers, w/ battery backup etc. Do yall think either of those would help?

Thanks again!

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 1:23 am

The glitches do NOT occur at the same time.
Not what I meant. If you do a capture with an error, does the capture's sound file play the error at the same time every time.


https://manual.audacityteam.org/man/dev ... ences.html

Scroll down to Latency > Buffer Length.


If you're in the US, you might invest in a simple wall power checker.

Image

I lived in two houses with wall outlets wired wrong. Nothing will screw up power line conditioners faster than having the wall wiring wrong. It's not exhaustive. The results are tilted. If it's says everything is OK, it's probably OK, if it says it's broken, you should stop using that outlet—now.

Surge Protectors are designed to protect your equipment if lightning strikes the power lines by your house. That's pretty much it. If the lightning strike is powerful enough, it will lift the house ground/earth connection and fry everything anyway.

Uninterruptible Power Supplies come in two general versions. The cheap ones that run the client (you) from the wall until something goes horribly wrong and then quick as a bunny switches to battery backup and hope nobody notices. The much better ones run the client from battery all the time and the only thing that happens during an outage is the battery stops charging. No switching, no interruptions, zip.

Which turntable?

Koz

kozikowski
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Re: Dropouts when recording improvements

Post by kozikowski » Wed Oct 14, 2020 1:43 am

A word on grounding. The turntable cartridge and arm are almost certainly connected to the air conditioner. Did you connect the slender black wire from the turntable to the phono amp or Phono Input of the mixer? Analog turntables have three wires, not two.

Most of the turntable hum and buzz goes away with that thin black connection. The connector looks like a tiny two-prong fork.

Screen Shot 2020-10-13 at 6.36.01 PM.png
Screen Shot 2020-10-13 at 6.36.01 PM.png (84.51 KiB) Viewed 343 times

That puts the turntable ground on the shield of the mixer or Phono Preamp. If the mixer has a three prong power plug, that puts the mixer case on the house safety ground system. Unless you have a 220 Volt A/C system, that connects the house safety ground system to the body of the air conditioner.

I wouldn't be shocked if the A/C kicking on and off can be heard. Another odd piece of this, bass notes don't fit in a record groove. They don't. So they are suppressed before vinyl pressing and they're boosted back to normal in the Photo Preamp. That's the RIAA system. The boost also includes all the bass interference in the turntable system. That's where hum lives. That's another reason for the third wire.

Koz

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