VU Questions

In a previous thread I posted, and elsewhere, I've heard people mention what VU levels they're able to record at normally, like +3dB or +5dB. I was just wondering if there was any kind of rhyme or reason to these numbers, or if they're somewhat arbitrary, based on whatever that cassette deck manufacturer decided 0dB was going to be?

I ask because I've had experience now with two different decks, with very different ways of determining VU levels, a Sony TC-K630ES and a Kenwood KX-3510.


Note that I'm not playing the same tape in those photos, I just included them as a reference of the specific displays I'm talking about, and because I think they look cool.

The Sony devotes many more individual segments for its VU display so I'd assume it was more precise. Its Dolby Level icon is between 0VU and 0dB, while on the Kenwood it's far past 0dB, in the red zone. The Sony also has a "saturation level" indicator (the red dots at the bottom of the display) that changes depending on the type of tape being used, and sure enough, if your levels get much past it, you start to hear distortion. Meanwhile, on the Kenwood, you can get far into the red before distortion becomes audible. Kind of makes you wish some consortium of audio manufacturers got together and came up with one set of guidelines for this sort of thing!

When I play a tape recorded on the Sony on the Kenwood, the VU meters are usually pegged off the scale most of the time, yet the recording sounds great.

I suppose it's part of the allure of tape, really. In addition to tape having its own 'personality,' each deck also has its own way of doing things. Do I have the right idea on VU levels (they're a reference for that deck's recordings and not easily applicable to others) or am I missing something?

Well i don't know much about cassettes, but tape is tape and in R2R format the OEM sets out what the deck is set at. Also depending on the type tape you use will determine where 0VU is. For instance on my Studer A810 0VU with SM468 type tape is +4db, and othe tapes will provide different db's accordingly.

Jay

In cassette decks there are 3 common reference levels:

0VU = 160 nWb/m (DIN method)
Dolby level = 200 nWb/m (ANSI method) = approx. 215 nWb/m (DIN method) = +2,6dB VU
DIN Reference level = 250 nWb/m (DIN method) = +4 dB VU .

Your SONY has 0dB at DIN reference, so 0VU becomes -4 dB and Dolby sign (Dolby level) is at -1.5 dB . This is common for many SONY decks, starting at least from TC-K75, 81 etc.

Nakamichi, on another hand, always put 0 dB on the meters for Dolby level. Many other manufacturers stayed with the oldest 0VU scale, your Kenwood deck is a good example of it.

Bear in mind that this is just different scales on the meters. Let's say, a particular tape saturates at +5 dB VU. It will happen at +1 dB DIN on a Sony deck but at +5 dB VU on Kenwood. On Nakamichi the same tape will saturate at approximately +2.6 dB on the meters.

Does all this make sense to you ?

Alex

Most cassette decks don't have real VU meters. They're more like peak meters. True VU meters tend to be costly. True VU meters are slower responding than the peak meters are.

KentTeffeteller said:

Most cassette decks don't have real VU meters. They're more like peak meters. True VU meters tend to be costly. True VU meters are slower responding than the peak meters are.

Click to expand...

That is another matter and it is related to the actual music signal level display. Some older decks had switchable time constants ("VU"-"Peak") for the meter, for example Technics RS-M85/88. However "0VU" for cassette decks is also an accepted reference level, set (I think) originally by Philips at 160 nWb/m (DIN).

Alex

Thanks for amplifying my post and explaining it in more detail. You are entirely correct on all counts. Excellent post! :tresbon:

Ah, thanks for the responses, it does make a little more sense now! I also figured there was a difference between VU levels and dB levels, as my Sony has an indicator for both 0 VU and 0dB, but wasn't sure about the specifics.

Obviously I don't need to really know about it to make good recordings, since I can just pop in a pair of headphones and listen for what sounds best, but I like to know the science behind what I'm trying to do.