Sangre de mi sangre

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One of the best of the recordings made by Rodolfo Biagi with Hugo Duval in the mid-1950s was Sangre de mi sangre, recorded for Odeon on 29 June 1954. There seem to be lots of versions available on the usual music listening sites and for download, but most of them turn out to be the much later version Duval recorded with Trío Yumba, and that’s not really my cup of tea.

I have only found the Biagi original in two distinct transfers (but they are widely duplicated); one is from the album Tango Classics 095: La copa del olvido and it has rather a lot of noise but sounds dull, while the other is from the album Sangre de mi sangre (1953 – 1959), which sounds rather better. Here are the two 30s clips available to preview the tracks:

The clips end just as Duval begins to sing (which is a shame) but the pitch/speed is very obviously too high/fast in both transfers. I measured the pitch in Audacity, using the nnls-chroma tuning plugin. The second clip reported tuning of A=431.7 Hz, suggesting that the tuning was 33¢ flat. However, as far as I can determine, the plugin is not reporting absolute pitch, but the variance from the closest standard key (ie the maximum it will report is 50¢ up or down). Where the tuning error is more than half a semitone, it may report 33¢ flat, when it should report 67¢ sharp, so judgement is required in interpreting the measured result. The correction required, here, is to stretch the sample by 3.795%. Not surprisingly, it now sounds rather better:

There is quite a lot of mains hum, so removing that (I use Brian Davies’ DeNoiseLF), improves the sound again. Here’s another 30s sample, but this time, picking up where the others finished – to hear the effect of the pitch correction on the timbre of Duval’s voice:

Of course, it shouldn’t be necessary to check the music files we buy for anything as basic as correct pitch, but it is comparatively rare to find something so far out of tune: a correction of nearly 4% completely alters the pace and feel of the song.

Pseudo-Stereo

I do most of my listening tests on headphones, as it’s easier to hear fine detail, but I don’t much like the ‘inside your head’ feeling I get when listening to mono recordings on headphones.

Just for fun, I sometimes render a song in pseudo-stereo, and I’ve been amazed at how it can bring a ‘difficult’ transfer to life. The effect is completely phoney, of course, and I’d never use it for my DJ library.

I combine two different effects: Audacity’s mda-stereo plugin and also one of the reverb presets (small room bright). I won’t bore you with the details of exactly how I do it, but here’s a 60s excerpt (combining both of the above samples) in ‘stereo’. You need headphones, really, to ‘enjoy’ the effect – but I think it actually sounds quite good, and it’s certainly good to hear the song in the proper key.


DJ Clive Harrison
DJ Clive Harrison

Barrio de tango is the tango blog and online home of tango DJ, Clive Harrison, based in the English Midlands. Now retired from teaching and hosting dance events, Clive remains available to DJ, playing exclusively traditional tango music from the great tango orchestras.