Overloading Input Meters

Hi! I’m new to this so bear with me. I have an old iMac running OS 10.4 (‘Tiger’ I think!) I downloaded Audacity in order to be able to convert some old Tascam portastudio recordings into digital files. Everything seemed to be working smoothly until I started to monitor the levels in Audacity. With the Stereo Output meters reading a max of 0dB on my (obviously ‘analogue’) portastudio it’s compl;etely off the scale when bringing it into Audacity ie: meters full on in the red!

I am connecting my portastudio via a stereo RCA connections lead terminating in a standard 1/8" connection which I’m inserting into the 1/8" line-in connection on the side of my iMac. I have Audacity set to: 32bit floating rate; Hi Def Line In recording enabled and recording to a Stereo file. Ideally I would like to record from my portastudio into Audacity with a max peak of -6dB but the closest I can get is -3dB … THIS IS WITH AUDACITY’S SLIDING SCALE INPUT LEVEL MANUALLY SET COMPLETELY TO THE LEFT (on a scale of 0 to 100 set to ‘0’ ie: absolutely no input from the looks of it!) I don’t understand. Could someone shed some light on what I might be doing wrong here? It seems crazy to have such high input levels in Audacity when the input source is set conservatively - it makes no sense to me whatsoever that, even with the Audacity manual recording level set to nothing, I still can’t control the levels to stop them over loading. PLEASE HELP!

Guess #1: You’re recording from the Porta’s headphone out?

Guess#2: The Porta has a pro level line-out. The Mac has a consumer level line-in?
Pro= 0 dB, 1V
Consumer = -10 dB, 100 mV.

Given that tapes tend to be “hot”, eg driven to +6 dB, you might get into trouble there.

It would probably help if you could find out the type of iMac and the type of Portastudio you have.

If the Porta has headphones you can record from then that lets you turn down the volume knob on Porta to reduce the recording level.


Hi and thanks for the advice so far! OK, first off my iMac is an old one namely an ‘iMac Power Mac 2.2’ [CPU: 750 / CPU Speed: 500 Mhz Power PC G3 / L2 Cache: 512KB / Memory: 256 MB SD Ram / Buss Speed: 100 MHz)] running OS: 10.4.11 so … quite old then! (Is it up for the job or am I asking too much of it? I dragged it out of the cupbaord, along with said portastudio, to be able to attempt this!)

I think I’ve downloaded Version 2.0.6 of Audacity if I remember rightly (I shall check this and ammend if I’ve got this info wrong (I’m not on my iMac right now) but I’m pretty sure it was v.2.0.6 I opted for.

As for portastudios I actually have TWO I want to transfer from both Tascam’s (namely a 424 Mk III four track and a 488 Mk II eight track). The reason I opted to transfer from the dedicate stereo RCA line outs was because I thought that this was the way to go in order to get the best quality transfers. Correct me if I’m wrong but, is the fidelity of the signal out from a heaphone socket not inferior in quality to that of a transfer from RCA sockets? (I don’t know why I think this - hopefully someone can prove me wrong here!)

Here’s what I’m trying to do in a nutshell. ANY advice as to how best to go about this would be greatly appreciated:


‘Please send me completed mixes in the following file format: 24 BIT .WAV FILES WITH A MAX PEAK OF -6dB’

What would be the best way to go about this? Thanks very much for the advice so far!

Yes in principle the extra gain stages of a headphones output “may” be noisier but you may not have a choice unless you can normalize the files to a lower level in PortaStudio, or unless PortaStudio allows transfer of the files to computer over USB.

Audacity 2.0.6 is the final version for OS X 10.4 - so you can’t upgrade Audacity.

Your machine is below 2.0.6 system requirements of 1 GB RAM/1 GHz processor. You could get recording dropouts but the below par machine would not cause the recording level to be too high.

Audacity’s Normalize effect can set the peak to any specified level. To export as 24-bit WAV, choose “Other uncompressed files” when you export and click the “Options…” button when you export.

What bit depth are the files in now on PortaStudio? If they are 16-bit, converting them to 24-bit does not improve them, it just makes them larger.


Hi Gale and thanks so much for your reply! The portastudios I am attempting to transfer my tracks from are analogue NOT digital machines (ie: bit rate resolution doesn’t apply right?) Both machines (namely: a Tascam 488 Mk II and a Tascam 424 MkIII) record to and playback from cassette TAPE. As I tried to explain, I am attempting to convert these purely analogue recordings as they stand into a compatible digital format in order to be able to send said recordings away to be properly mastered.

OK, how do I go about getting the closest, truest-sounding-to-my-original-analogue-recording digitally converted sound file ideally using what I’ve got (namely: an old iMac and/or a Laptop running Vista) or ‘something else’ (on a very limited budget this end!)?

Listening back through my powered monitors plugged directly into the monitor RCA outs on the back of my tape portastudio I am pretty happy with the sound HOWEVER listening back to the same tracks converted to digital they just don’t sound anywhere near as good digitally. WHY? I just want these converted digital sound files to mirror a true representation of my original taped source material.
PS: If the limited digital gear I have at my disposal this end doesn’t ‘cut it’ then what can I use (again on a budget!) to get a decent sound once transferred from analogue to digital?

Hang on a minute … noob user error alert methinks! See that little volume slider I’ve been talking about? You know, the one with the MICROPHONE symbol? Hmm … I’ve been turning that up to about midway on the scale. That’s right, the MIC input! No wonder my levels have been going off the scale! What an idiot eh??! OK, off to try again …!

Does your Mac have a connection like the one on the left?

That appeared on older machines. That’s your stereo Line-In. You can directly cable that to the headphone out of your music player. That’s how I record my music keyboard.

Do your music players have a volume control? If so, use that to set the levels and leave the Mac and Audacity records settings at max. Adjust so the music peaks run about 50% on the blue waves and -6dB on the sound meters. About like this.

converting them to 24-bit does not improve them

It does do one very important thing. It makes the client happy.

See: I deliver voice tracks in stereo not because it makes them any better, but because I know that’s what the editor is expecting.


I did not realise the recordings were stored on tape. :wink:

But anyway, if 7track’s Mac has a stereo Line-in, make sure in /Applications/Utilities/Audio MIDI Setup that the Line-in is set to 24-bit, and Audacity is set in Quality Preferences to 32-bit float or 24-bit Default Sample Format.



Here’s my set up with relevant screenshots of where I’m at …

Hi Koz! My Mac is ancient compared to that one (see pics I have uploaded below) IT’S A DINOSAUR! (I’m also beginning to think it has a max of only 16-bit!)

It’s a iMac G3, the inputs are 16 bit only, I seem to remember.

Yes, it very much seems that way Cyrano. Is it JUST the inputs or the entire iMac G3 machine do you know? What I mean is, if I get a 24-bit USB/FW interface and bypasss the side panel 1/8" input will I get 24 bit recordings this way? Heck, do I even need 24 bit recordings??! Does it make a difference since everything gets dithered down to 16bit anyway for CD (which is where I want these recordings to end up eventually - after they’ve been mastered).

If you are careful when setting recording levels (maximum peak at about -6 dB), then 16-bit will be fine.

24-bit can be very useful when recording live audio where the dynamic range can be extreme - in particular, amateur players can be highly inconsistent with their playing volume. With 24-bit recording and high quality (pro/semi-pro) equipment throughout, it’s possible to allow 20dB of “headroom” (rather than 6dB) without sacrificing sound quality.

Is there anywhere you can toggle the external input between microphone and line-in? Perhaps in Sound in the System Preferences? I can’t find out, but you should check. In the picture of your recording there seems to be almost no stereo information (difference between left and right).

If you have no such toggle possibility you might get better sound using an interface, irrespective of the 16-bit/24-bit question - if the computer can keep up with the recording. That could (possibly) be harder over USB or you might not meet the system requirements of the interface.


Yes. Internally, there’s no limit as to bitdepth. I’ve never tried it and as the CPU will be 50% more taxed, it could be not-so-easy.

I don’t think you need it. Tape doesn’t have 120 dB of dynamics. More like 60 dB and that should fit fine in 16 bit.

I’ve looked up your Mac. It’s the “Summer 2000”, DV edition. “DV” stands for digital video. It should really work well for audio as it has been optimized for video.

If you need to spec your Mac in the future, you can use this link:


Have you ever tried the third possibility in Audacity’s input list “sound input”?

That could be the line input, I think. But frankly, I don’t remember clearly, as it’s a long time ago…