Mac: Audacity recording slider greyed out on maximum

Audacity 2.0.6, .dmg installer (I think)

2013 iMac, OSX Yosemite 10.10.3, loaded

Input device: Novation Audiohub 2x4 (USB)

I’m trying to record hi-res sources that aren’t easily ripped bit-perfect (vinyl, SACD etc) in 24/96. Rather than use a pricy 24/96 ADC, I found the Novation Audiohub 2x4, a relatively new product which seems to be Mac-friendly (class compliant USB, no drivers needed). It is intended for DJ or studio recording, but has RCA analog-in and USB 2.0 out, and everything I read suggests that my project should work. Link:

And it seems to work, except for only one (important) detail: I can’t set Record levels. The recording slider is greyed out on maximum. It’s available when the Device is switched to the default Built-In Mic, but greys out when switched back to the Audiohub 2x4.

I won’t pretend I’m expert at this, but I did go through the Audacity set up twice, and set the input device for the Audiohub at each available station: Audacity Preferences (confirmed in project window), System Preferences > Sound > Input, and Audio MIDI > Input. Along with the desired bit depth/sample rate, 24/96. Pretty sure there are no conflicting setups.

I must have done something right. Music signals get through, Audacity records, I can save. But I do need to adjust levels somehow.

One detail about the Audiohub 2x4 that might be relevant: there is no variable level control, but there is a simple Gain / No Gain switch. Of course, Gain clips and No Gain would require amplifying after the fact.

Prior to this, I’ve only used Audacity to set levels for party mixes, or change formats, and for that it’s worked fine for years.

Any ideas? Thanks in advance.

That’s normal. Apple assumes if you have a digital connection that it shouldn’t mess with it. So it doesn’t. Attached is the panel for Sound Preferences (click on the graphic).

Screen Shot 2015-06-30 at 16.56.38.png

That’s old Mac news. Windows machines frequently do allow volume changes on USB connections, but they come with their own problems.


If you have a slightly older Mac, you may already have a terrific A/D.

I’ve used that circle with two black arrows connection for broadcast radio shoots.

It’s not the crappy afterthought that Windows connections are.


Hey Koz

Thanks for the reply.

Yeah, that’s what I’ve been looking at.

So “that’s normal” means there is no input device level control, period?

If so, I do have a spare audio preamplifier I can put between the SACD player and the Audiohub device. Clunky arrangement, but it’s a clean, neutral piece wherein I can control levels, I guess.

Or maybe I can try doing this recording in GarageBand, though it seems wimpy. Maybe it’s more Apple-centric.

I do have an '08 Snow Leopard iMac. I never use any computer’s audio jacks, as those connections and cables appear EXTRA-wimpy. Nonetheless, any idea how you determine the exact spec for those kinds of multi-purpose plugs? Apparently they come in different sizes; just something else I’ve been stung with while trying to deal with computer audio.

Thanx again,


If you set the switch to “No Gain”, how much level are you getting in Audacity? (how much amplification do you need to apply “after the fact”?)

We should also remember that if you have a digitally overloaded signal in Audacity, if you lower the volume, you will have lower volume digital overload. You don’t get the bits back. That’s one reason it’s valid not to have digital volume controls in the pathway.

Only the pure Stereo connection has that logo on it. I think there’s actually an option to plug a headset in there, but I don’t know anybody who did that. These machines had hidden options.

Macs did come with a multi-function socket and I know less about those. I would try plugging a standard stereo 1/8" plug in there and mess with the settings in Apple (upper left) System Preferences > Sound.

Some machines will have System Preferences > Hardware > Sound. You may be able to change configuration.

A friend has a 12" MacBook Pro and he only has one connection for Stereo In and Stereo Headphone Out. He changes direction in Systm Preferences.

I went to some effort to make sure I had machines with good sound connections. Four times. Two MacBook Pros and two Minis.


You know these machines have optical digital audio, right? Optical S/PDIF.


I trashed my test files, so no precise measurement. There was a visible signal, which looks like it would take about 9dB of amplification to get “right.”

Seems it would be better, for accuracy and convenience, to record it correctly the first time, yes?

I agree regarding digital volume control.

My newer iMac has an audio connection, but it’s headphone-out only. That’s just how new Macs are rolling anymore.

I could possibly use the older iMac with its more-flexible audio connection, but the whole idea of this exercise is to capture hi-res 24/96 copies (from SACD mostly). Large files, recorded in real time. I’d rather have the more powerful desktop manage this. It’s starting to look like the simplest solution will be to add the analog pre-amp into the chain.

Thanks for the replies, guys.

Given that we generally recommend recording with a peak level of around -6 dB (for 16-bit recording), the recording level sounds as if it is not far off “ideal”.

The dynamic range of 24 bit audio greatly exceeds the “usable” dynamic range of either the analog components in your system or the room in which you are listening (assuming that you don’t live in an underground bunker). The major benefit of 24 bit recording is that this massive amount of dynamic range means that it is not necessary to push the levels up to the limit. It does not surprise me that a 24-bit recording has a few dB of headroom.

Probably not. Amplifying digitally will be both more accurate and less noisy than adding more analog components to the chain. Assuming that you use the default 32-bit float format in Audacity (recommended), digital amplification will be accurate to approximately 0.0000000000001 % (much better than the best analog equipment).

I guess. But in the case of SACD or vinyl, it’s analog to start with, and once it gets played thru analog gear, background noise levels aren’t discernible. Or at least not here, anyway.

I acknowledge all your talking points, Steve. We’re dealing in tiny nuances with hi-res as far as I’m concerned. I’m underwhelmed with SACD, and hope to never buy another one. (Except for 5.1 surround :sunglasses: ) I buy for content, not format.

Meanwhile, for the couple dozen SACDs I have, I feel compelled to squeeze what I can out of them for the server. Even if the difference is negligible. I do have a couple titles that sound discernibly better on the SACD layer than the Redbook layer. But even then, it’s not a night-and-day difference. It could be simply the disc mastering. the human factor.

I might spend small money on a long cable to the old iMac – if I can ever figure out what that exact plug size is (really hard to research that for some reason) – and do a comparo.

Thanx again.

For 9 dB at 24 bit, I wouldn’t even bother. It’s a safe distance from digital clipping. And amplifying it digitally would add little to the noise floor.

I’d even bet using the built-in 3,5 mm analog jack would be worse over a longer cable.

And I always wonder why nobody uses the optical sp/dif in that plug. Is is too hidden? Is it the custom Apple plug?

As far as I’m concerned, it’s the best way to connect any laptop since it is the only way that provides perfect electrical isolation. No ground loops, ever.

There is no transmission of SACD/DSD signals over optical (or coax digital). Only analog. (Or HDMI to a specialized DAC that can handle it.) For server/archiving purposes, SACD = vinyl.

There is a way to rip SACD digitally, but it is very complicated, and involves arcane hardware, and modification thereof.

Otherwise, I appreciate your feedback re: amplifying and the long analog cable.

I’ve got some experimenting ahead of me.

Just thought I’d enter a wrap-up in case anyone else is recording in this manner.

Long story short: everything works fine.

The answer to the immediate dilemma was/is: Apple doesn’t allow adjustment of recording levels in Audacity when connecting a USB device such as my AudioHub 24/96 ADC. It’s an Apple thing, not an Audacity thing.

The test SACD I initially used coincidentally had an extra-low db level, and I did apply post-record amplification, but it required no more than 5db. Subsequent recordings appear very close to “normal” and require little or no amplification. Maybe it’s just a lucky catch that the low-gain switch on my input device creates a proper-level signal for recording. But regardless of inability to set precise recording levels, I should be set to make good recordings going forward. Everything sounds fine.

Thanks to everyone who responded.