Output from phono stage too low for good digital recordings

[LateJunction]

I have a small problem of understanding terminology and technology in trying to find a solution to an audio issue I have – could I get some advice please?

First the issue: recordings I make from vinyl in Audacity are much too low in volume, so the histogram looks like a crinkly straight line with the average recording level (as shown by Audacity) being about -36 to -24 dB, with orchestral crescendos going to about -12 dB, instead of -3 to -1 dB that I am expecting. In contrast, when I’m recording from FM Tuner, CD or cassette, I see a recording histogram which looks like a set of large horizontal Christmas trees (that’s about as technical as I can get…), with average recording level of about -12 dB and frequent peaks at -3 dB.

Kit being used is Rega P7 + Dynavector DV20X2 Low + Cambridge Audio Azur 640P phono stage + Behringer UCA-202 + short USB cable to laptop with Linux Mint 18.1 XFCE + Audacity. (Adding an AudioLab 8000Q between the phono stage and the Behringer ADC, using the tape outputs of the 8000Q, makes little difference).

The problem is that the output from the Dynavector cartridge is only 0.3mv and the gain of the 640P phono stage is only 55dB. But I cannot work out, using these figures, what the voltage output from the 640P is and how that compares to the input required by potential replacements of the Behringer UCA-202. Most of these require about 500 mV rms. Can somebody explain to me how I can calculate the nominal output of the 640P?

As a secondary question, could I have some recommendations on a suitable ADC that will give me 24/96 or even 24/192 or even DSD? I have been looking at:

* Novation 2x4 AudioHub (basically a Focusrite Scarlett Solo re-engineered for domestic use rather than professional audio)
* Focusrite Scarlett 2i2
* M-Audio M-track 2x2 C series
* ADL Furutech GT40a
* Korg DS-DAC10-R

I have the impression that I will not be able to drive any of these devices to -1 dB recording level with my kit. Any recommendations?

[Stryder5]

Have a look here, see if it helps.

https://www.kabusa.com/pregain.htm

Looks like you need 61 dB of gain

From the 640p manual they state 0.5-1.0 input

https://techsupport.cambridgeaudio.c..._-_English.pdf

[LateJunction]

Have a look here, see if it helps.

https://www.kabusa.com/pregain.htm

Looks like you need 61 dB of gain

From the 640p manual they state 0.5-1.0 input

https://techsupport.cambridgeaudio.c..._-_English.pdf

Excellent reference - thanks. Confirms my suspicion that I should be looking for a phono stage with 65 dB gain (to give myself a little margin for error).

[Light Dependant Resistor]

I have the impression that I will not be able to drive any of these devices to -1 dB recording level with my kit. Any recommendations?

Digital levels are always held back because of risk of overload. However a read of this paper will show you technique to overcome that limitation
ftp://ftp.dbxpro.com/pub/pdfs/WhitePapers/Type%20IV.pdf

Cheers / Chris

[Infinitely Baffled]

Hello, Tony. Arkless Electronics, who have a trade room here on AoS, have developed a highly regarded phono stage which uses your Cambridge Audio stage as a "donor" unit. My understanding is that it is rather more than an upgrade of the Azur 640P. It is in effect a redesigned phono stage which uses the Azur as a basis. I don't know whether part of the Arkless spec involves a higher gain than the original donor unit, but my guess is that if you speak to Jez Arkless, he will be able to incorporate that specific requirement, if it is not a standard part of the redesign. I would have a word with him, if I were you. Good luck in sorting the problem.
IB

[Rothchild]

I wouldn't let it bother you, 0dBvu = -18dBFS ie when the record was cut and the needles on the meter went through 'zero' that would only make -18 on a 24bit digital meter.

If you're recording at 24bit you're capturing all the range on the record anyway, further analogue gain just risks pushing more analogue noise in to your recording. If you're really unhappy about the appearance of the file, or you want to have the files at a level where they match other sources just normalise them in audacity.

[mike1210]

Been recording vinyl for years and made several mistakes along the way. Soundcard with input-trim is essential to get the levels right. A drum a bass single running at 45rpm is way louder than a 33rpm album with 30 minutes of music on one side, getting a phono stage with more gain will only fix part of it if the input stage of the soundcard can't be set.

Many people have the opposite problem to what you have, the output from the phono stage has way too much beans on it. Some output up to 4VRMS.

Used a Focusrite Saffire for years with input trim on the left and right channels which is very useful. My Dino was overloading my previous card so had to get a new one.

Now with a RME Babyface Pro which isn't cheap but awesome.

Looking at your system, I'd highly recommend a better sound card to get decent quality recordings.

Mike :-)

[Arkless Electronics]

Hello, Tony. Arkless Electronics, who have a trade room here on AoS, have developed a highly regarded phono stage which uses your Cambridge Audio stage as a "donor" unit. My understanding is that it is rather more than an upgrade of the Azur 640P. It is in effect a redesigned phono stage which uses the Azur as a basis. I don't know whether part of the Arkless spec involves a higher gain than the original donor unit, but my guess is that if you speak to Jez Arkless, he will be able to incorporate that specific requirement, if it is not a standard part of the redesign. I would have a word with him, if I were you. Good luck in sorting the problem.
IB

Cheers Gary

The OP rang me yesterday actually for advice on this and we discussed this option.... I also suggested that he could take the output from his pre amp (the main outputs, not the tape outs which he was trying to use) and thereby, assuming the line stage has gain, boost the output from the phono stage to a suitable level.
The Arkless 640P has much higher output than the standard one (an AOS member with one on order has actually asked me to reduce the gain a bit on his!) at 64dB but I can customise for any gain at no extra cost.
This would vastly increase the quality of the sound as well of course! Much more so than a better sound card!

[cre009]

Some observations from my own experience.

I briefly had a go at doing transfers using the Peppermint Linux Distro (a variant of Mint) and also found the recording level was too low using an external Sound Blaster ADC. The Sound Blaster worked ok on Windows so suspect the problem may be within Linux. On Windows for two of my ADCs I can change the recording levels via control panel settings and would expect the same within Linux. However I am not an expert on Linux myself so would suggest placing a question with the Linux Mint Community forum.

For 24 bit recordings you really need to be using "Jack" in Linux or "ASIO" or "WASAPI" in Windows.

I have both the ADL GT40a and Novation Audiohub 4X4 out of the devices you mention. I use ASIO in Windows myself for 24/96 and both give me very good results as an ADC. There is a thread at Vinyl Engine on the ADL GT40a which I participated in. I really like the unit which is versatile though caution that the phono stage is adequate rather than great. There are 3 gain settings on the box itself but gain can also be controlled via the Windows Control panel.

For some reason the gain for the Audiohub can only be controlled via a switch on the box. Gain on the Windows Control panel is greyed out. The 2 settings are ok but not flexible enough for my liking so I use a Nakamichi Pre Amp to control the input gain for transfers via the Audiohub.

[LateJunction]

Hello, Tony. Arkless Electronics, who have a trade room here on AoS, have developed a highly regarded phono stage which uses your Cambridge Audio stage as a "donor" unit. My understanding is that it is rather more than an upgrade of the Azur 640P. It is in effect a redesigned phono stage which uses the Azur as a basis. I don't know whether part of the Arkless spec involves a higher gain than the original donor unit, but my guess is that if you speak to Jez Arkless, he will be able to incorporate that specific requirement, if it is not a standard part of the redesign. I would have a word with him, if I were you. Good luck in sorting the problem.
IB

Thank you for this recommendation. I have indeed spoken to Jez who was more helpful than I had a right to expect, given that my call was totally unsolicited. He made a suggestion (which to me is a measure of the man) to try a zero-cost alternative first before spending any money. I'll be making a further call to Jez soon I suspect!