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Levels to use when recording vinyl, do I need amp before line-in, etc., [split from “Archiving vinyl once only 96/24?”/thread 100121/TOS #5]
zerowalker
post Mar 30 2013, 03:45
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Little off topic maybe, but if you use Line In on a compture to record.
Is the volume of that Line In the same as using an Amp?
Or is the volume corrected after it has been digitalized?

Just wondering as i also want to maximise ADC coverage.
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AndyH-ha
post Mar 30 2013, 09:13
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A professional line level input is just an input. It may be switchable between the two line level standards, +4dBu and -10dBV (professional and consumer), but it is not variable. In a mixer interface there could be a line level preamp (generally providing +10dB or +12dB gain and some larger attenuation), but that is an extra, not actually part of a real line level input. Gaming and entertainment cards are a whole different thing and must be investigated individually.

The input controls on most ADC are digital, after the signal has been sampled, and are best set at maximum. They cannot prevent clipping, and they cannot improve on the ADC output.

Mostly, for taking the signal from a phono preamp, the consumer level line-in is appropriate. The +4dBu input expects a much higher level signal and would thus be recording way down from 0dBfs of the ADC, but there are exceptions.

The outputs of both phono cartridges and phono preamps vary considerably from one construction to another. Sometimes the combination you happen to have produces a very good signal for your ADC line in, sometimes you need to adjust up or down.

If the signal level is too high, it will clip in the ADC and that cannot be corrected post recording; it must be done in the analogue domain.

Signals that peak as much as 20dBfs down are probably quite ok, and can be normalized after recording. If that doesn't satisfy you, or if you need to attenuate the signal before the ADC, you need a line level preamp between the phono preamp and the line level ADC input. A small analogue mixer is usually the least expensive fix.

If you just need attenuation, a passive volume control, or even a fixed resistor attenuator, isn't hard to implement.
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zerowalker
post Mar 30 2013, 09:44
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Not sure i understood all that.

But atleast i understood the ADC volume being after itīs been made digital, thanks for clearing that out for me.

But what i donīt understand is, does it matter if itīs low when you capture it, is there a reason to make it higher before being digital?

I am asking cause i do it with VCR, but itīs probably pretty much the same thing with vinyl, as both are analogue, though i donīt know if vinyl players got a volume, as VCR doesnīt.

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Paul Sanders
post Mar 30 2013, 10:37
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QUOTE (AndyH-ha @ Mar 30 2013, 09:13) *
The input controls on most ADC are digital, after the signal has been sampled, and are best set at maximum. They cannot prevent clipping, and they cannot improve on the ADC output.

You keep saying that but it's not true. What makes you believe that?


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zerowalker
post Mar 30 2013, 11:01
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QUOTE (Paul Sanders @ Mar 30 2013, 10:37) *
QUOTE (AndyH-ha @ Mar 30 2013, 09:13) *
The input controls on most ADC are digital, after the signal has been sampled, and are best set at maximum. They cannot prevent clipping, and they cannot improve on the ADC output.

You keep saying that but it's not true. What makes you believe that?


Wait, so it isnīt true?

Is the volume amplifying the signal before itīs converted?
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Paul Sanders
post Mar 30 2013, 11:11
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QUOTE (zerowalker @ Mar 30 2013, 10:01) *
Is the volume amplifying the signal before itīs converted?

Or attenuating, yes.


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zerowalker
post Mar 30 2013, 12:17
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QUOTE (Paul Sanders @ Mar 30 2013, 11:11) *
QUOTE (zerowalker @ Mar 30 2013, 10:01) *
Is the volume amplifying the signal before itīs converted?

Or attenuating, yes.


So, an amp isnīt needed at all before the Line In?
Except if the signal is still to low or hight no matter the volume.
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Paul Sanders
post Mar 30 2013, 13:24
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QUOTE (zerowalker @ Mar 30 2013, 11:17) *
So, an amp isnīt needed at all before the Line In?
Except if the signal is still to low or high no matter the volume.

That's correct. It's almost always unnecessary, with any reasonable line-level source and any reasonable sound card. Just adjust the recording level slider to get a decent level, as people have recommended earlier in this thread.

If recording from a phono source, you still need a phono preamp of course, and some budget / semi-budget USB devices have a fixed recording level, sad to say. What then causes a lot of confusion is that Windows Vista and later offer a digital slider, which is unhelpful and unwanted (VinylStudio offers a button in this case to set the digital gain to 1, with a recommendation to use it, and tough luck if it clips).


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zerowalker
post Mar 30 2013, 13:28
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QUOTE
What then causes a lot of confusion is that Windows Vista and later offer a digital slider


What do you mean?
Is the volume slider in Volume(in sound settings) Digital?
Or am i confusing things.

QUOTE
If recording from a phono source, you still need a phono preamp of course


May be stupid here, but isnīt Phono = RCA?
Why do you need an amp for that?

This post has been edited by db1989: Mar 30 2013, 14:52
Reason for edit: deleting pointless full quote of above post
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Paul Sanders
post Mar 30 2013, 13:50
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QUOTE (zerowalker @ Mar 30 2013, 12:28) *
What do you mean?
Is the volume slider in Volume(in sound settings) Digital?
Or am i confusing things.

I'm referring to the recording level slider, and it's digital only in the case where the sound card (or, in practise, USB device) has no hardware input level control. I told you it was confusing, what they (MS) have done is daft.

QUOTE (zerowalker @ Mar 30 2013, 12:28) *
May be stupid here, but isnīt Phono = RCA?
Why do you need an amp for that?

By 'phono source', I meant an unamplified pickup cartridge. You need a phono preamp for that to boost the signal to line level. USB turntables contain one, before the ADC and USB controller chip. Some conventional turntables now contain one too, just to muddy the waters.


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zerowalker
post Mar 30 2013, 14:15
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But, doesnīt that then mean that if i increase the recorder slider on my line in, it only changes the digital volume, not the analogue before the conversion?

Not sure what you mean with unamplified, when is it that?
Is a normal VCR output amplified for example?

Sorry, many terms i am not familiar with.

This post has been edited by db1989: Mar 30 2013, 14:52
Reason for edit: as above
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Paul Sanders
post Mar 30 2013, 14:33
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QUOTE (zerowalker @ Mar 30 2013, 13:15) *
But, doesnīt that then mean that if i increase the recorder slider on my line in, it only changes the digital volume, not the analogue before the conversion?

The slider is digital only for those devices with no hardware level control. If the device has a hardware level control (as most do), the slider controls it directly and changes the signal level *before* it enters the ADC. Windows XP (and Mac OS X) get it right. They hide the slider when the input device has no hardware level control (and set the digital gain to 1).

QUOTE (zerowalker @ Mar 30 2013, 12:28) *
Not sure what you mean with unamplified, when is it that?
Is a normal VCR output amplified for example?
Sorry, many terms i am not familiar with.

By unamplified, I mean the signal coming direct from the pickup cartridge. Then you need a phono preamp. VCR's, CD players, cassette players and whatnot all have line-level outputs and can be fed into your sound card direct. Phono preamps also provide a line-level output suitable for feeding into a computer.

We're way off-topic, really.


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zerowalker
post Mar 30 2013, 14:36
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Ah, so XP only showed the slider when it was "analogue" and Vista++ shows it no matter what?

Well, if most sound cards have it, i probably donīt have to worry.

What is pickup cartridge?

Yeah sorry for taking it off topic, but a moderatior seems to have moved it, so moderator, Thanks for that:)

This post has been edited by db1989: Mar 30 2013, 14:52
Reason for edit: as above
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aztec_mystic
post Mar 30 2013, 14:44
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QUOTE (Paul Sanders @ Mar 30 2013, 10:37) *
QUOTE (AndyH-ha @ Mar 30 2013, 09:13) *
The input controls on most ADC are digital, after the signal has been sampled, and are best set at maximum. They cannot prevent clipping, and they cannot improve on the ADC output.

You keep saying that but it's not true.

Which part do you consider false? The statement that the input controls on most ADCs are digital?

All the ADCs I use--that includes onboard audio as well as some semi-pro gear--lack an analog input gain. It actually became an issue during vinyl recording a few times. Specifically, in certain scenarios, the ADC would clip. Turning down the volume of the recording device in Windows didn't help. It led to nothing but an attenuation of the already-clipped signal.
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julf
post Mar 30 2013, 14:47
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QUOTE (zerowalker @ Mar 30 2013, 14:36) *
What is pickup cartridge?


The box at the end of your tone arm that holds the needle smile.gif

Think of it as a microphone that picks up the waveform from the groove in the vinyl - but a microphone that produces a very small voltage, and one that needs a significant frequency response correction (RIAA curve) applied. So a phono preamp is a special sort of amplifier that amplifies that signal to line level and applies the required correction.
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Paul Sanders
post Mar 30 2013, 16:30
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QUOTE (aztec_mystic @ Mar 30 2013, 13:44) *
Which part do you consider false? The statement that the input controls on most ADCs are digital?

Yes.

QUOTE (aztec_mystic @ Mar 30 2013, 13:44) *
All the ADCs I use--that includes onboard audio as well as some semi-pro gear--lack an analog input gain. It actually became an issue during vinyl recording a few times. Specifically, in certain scenarios, the ADC would clip. Turning down the volume of the recording device in Windows didn't help. It led to nothing but an attenuation of the already-clipped signal.

That certainly runs counter to my own experience. All the onboard audio I have ever encountered has a hardware (analog) level control. The only devices I have encountered with no hardware level control are USB devices using the TI 290x chip. This includes the NAD PP-3i, ART USB Phono Plus and Behringer UCA 202.

I will write a little program to display whether any particular input device has a hardware level control and post it here (Windows has an API call to tell you). You can then run it against whatever devices you happpen to have and report back. Of course it's always possible that a device has a hardware level control implemented after the ADC (but that would be weird - what would be the point?), or that the input signal exceeds an anlog hardware level control's ability to compensate (unlikely in the case of vinyl).


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Paul Sanders
post Mar 30 2013, 16:58
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QUOTE (zerowalker @ Mar 30 2013, 13:36) *
Ah, so XP only showed the slider when it was "analogue" and Vista++ shows it no matter what?

Yes, that's right. That's progress for you.


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Paul Sanders
post Mar 30 2013, 19:08
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OK, I have written a little utility to report whether or not each of the input devices on any particular system does or does not have a hardware input level control. It runs on Windows Vista or later (the information is not available on XP) and you can get it here:

http://www.alpinesoft.co.uk/private/report...vel_control.exe

Here is what is reported on the two systems I have here. Both are running Windows 7 and have Intel High Definition Audio Device (HDA) on-board audio, which is very common on machines purchased in the last few years:

System 1:

Microphone (High Definition Audio Device) DOES have a hardware level control
Line In (High Definition Audio Device) DOES have a hardware level control
Microphone (iMic USB audio system) DOES have a hardware level control
Line (ADL GT40 USB DAC) DOES have a hardware level control
Line In (ADL ESPRIT USB DAC) DOES have a hardware level control
Microphone (USB Audio CODEC) does NOT have a hardware level control (this is a NAD PP-3 phono preamp)

System 2:

Microphone (High Definition Audio Device) DOES have a hardware level control
Line In (High Definition Audio Device) DOES have a hardware level control
Digital Audio (S/PDIF) (High Definition Audio Device) does NOT have a hardware level control

The ADL GT40 and Esprit are relatively high-end devices (especially the Esprit). The only devices without a hardware level control are the NAD PP-3 as previously mentioned (reported by Windows as USB Audio CODEC) and the S/PDIF input (which I guess makes sense).

I'd be interested to know what other HA members' systems report. It might also be possible to determine this information on OS X, if anyone is interested.


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aztec_mystic
post Mar 30 2013, 19:52
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Thanks for this tool! This is from my laptop (Arrandale/first-gen Core):

System 1:

Rec. Playback (IDT High Definition Audio CODEC) DOES have a hardware level control
Microphone / Line In (IDT High Definition Audio CODEC) DOES have a hardware level control
Dock Mic (IDT High Definition Audio CODEC) DOES have a hardware level control


I'll edit this later to add the other sound cards of which I think (thought) they don't have a hardware control.
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2Bdecided
post Mar 30 2013, 20:20
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QUOTE (Paul Sanders @ Mar 30 2013, 09:37) *
QUOTE (AndyH-ha @ Mar 30 2013, 09:13) *
The input controls on most ADC are digital, after the signal has been sampled, and are best set at maximum. They cannot prevent clipping, and they cannot improve on the ADC output.

You keep saying that but it's not true. What makes you believe that?
Because he was talking about pro and semi-pro sound cards, where it is true. At best, two fixed levels is all you get. The attenuation and gain in the mixer is useless because it's in the digital domain.

No reason, other than luck, for the output level of one device to match the input level of another. The standard, such as it is, is 2Vrms = digital full scale. I have plenty of CD players, DVD players, etc that work to this standard. My Audiophile 2496 sound card does not. No turntable/cartridge/pre-amp combination I have does. Sometimes it's close enough, sometimes you get hopeless clipping, sometimes you get a hopelessly low level. In the latter two cases, you need to do something to change the level of the signal before feeding it into your sound card.

I've never used a consumer sound card (like a Sound Blaster etc etc), but typically they do change the gain in the analogue domain when you adjust the controls in windows.

Cheers,
David.

This post has been edited by 2Bdecided: Mar 30 2013, 20:20
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Paul Sanders
post Mar 30 2013, 20:29
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QUOTE (2Bdecided @ Mar 30 2013, 19:20) *
Because he was talking about pro and semi-pro sound cards, where it is true. At best, two fixed levels is all you get. The attenuation and gain in the mixer is useless because it's in the digital domain.

OK, thank you. My experience of these up-market devices is limited, but it seems a strange limitation. Perhaps they want to sell you an attenuator.

Care to run my little utility on the devices you own? I'd be interested to know what it reports. The insidious thing about Windows (XP excepted) is that it completely hides this vital information.


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Paul Sanders
post Mar 30 2013, 20:34
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(Edit:) Added a 'set digital gain to 1' button for devices with no hardware level control. Thought it might be useful. (End edit.)


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AndyH-ha
post Mar 30 2013, 21:05
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If the OP question was primarily about a phono preamp, then the answer is yes, it is needed. There are some possible work arounds, such as using a modified microphone preamp and doing the RIAA EQ in software, which appeals to some small number of people for reasons understandable only to themselves, but phono cartridges alone cannot drive an ADC to reasonable levels.

No software test is needed to verify that the controls on most non-gamming, non-entertainment sound cards work only in the digital domain. The schematics, even just functional schematics, make that clear. The reason isn't to sell an extra attenuator, it is because there is normally a controllable signal chain prior to the ADC input.

I've seen the statements that the distortion and noise specs on many built-in soundcards these days is low enough to be adequate for LP recording and also the claim is that their internal resampling is much improved over what used to be standard, but I think I would still record at 48kHz if I were forced to use such a device.

My statements were not about microphone inputs, which almost always have gain controls and often also have output level controls. Microphones and phono cartridges have some similarities but their preamp requirements are generally different.
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Paul Sanders
post Mar 30 2013, 21:29
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QUOTE (AndyH-ha @ Mar 30 2013, 20:05) *
No software test is needed to verify that the controls on most non-gamming, non-entertainment sound cards work only in the digital domain. The schematics, even just functional schematics, make that clear. The reason isn't to sell an extra attenuator, it is because there is normally a controllable signal chain prior to the ADC input.

I disagree with you there. Thanks to Microsoft's silly slider, I think there is a lot of confusion on this issue, certainly amongst less technically-aware users. There's not even an easy way to set the digital gain to 1. In fact there is no way, short of a software utility to do it, which is not good news considering how important it is. Before making changes to VinylStudio to make this easier on the user, I used to get a lot of support calls about this.


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zerowalker
post Mar 31 2013, 07:37
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Thanks for the software, it showed that all of mine had hardware control currently.
Really bad indeed that you wonīt know it unless a software tells you.

Appreciate it for telling me, probably many more then me that didnīt know about this.
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