I can be a grumpy dancer and one of my pet hates is mixed tandas.
Lots of orchestras recorded a wide selection of repertoire from which good tandas can be compiled – with songs that are thematically or stylistically related and which work as a satisfying coherent group. However, the majority of orchestras recorded proportionately fewer milongas than tangos and valses. In the usual tanda cycle system, every sixth tanda danced is milonga, but the repertoire is small. Considerably fewer than one in six recordings in my library, for example, are milongas.
There is a temptation, looking at the available repertoire of milongas, to put together combinations that just don’t work: clashes of style, period, singer, orchestra. I’ve heard plenty that just seem to be random: “here are three songs I paid* good money for, I’ll play them together, regardless”. Come to think of it, some DJs seem to do that for tango and vals too, but there we are.
It isn’t a fixed rule, but many DJs (and dancers) prefer tandas that do not mix instrumental recordings with vocal ones, and if the tanda is a vocal one, do not mix singers. My own Tango 250 collection has eleven milonga tandas, but only two are ‘mixed’. In my companion Tango 500 collection (which is my follow-on complimentary collection that expands the range of orchestras in both depth and breadth) there are seven unmixed tandas and four mixed ones.
There are some popular songs (eg Mi vieja linda (1941) recorded by Pellejero) which you have to combine with other orchestras if you’re going to play it at all. As it happens, I never have played it – but the time has never felt right, but the objection isn’t on principle.
So my gripe is with DJs who mix their milonga (and sometimes vals) tandas as a matter of course. Usually, they are mixing orchestras and periods, as well as instrumentals with singers. The milonga tandas become a dustbin for all the odds and ends they deem too good to waste. We’ve probably all made mid-week supper from the odds and ends in the bottom of the fridge – that sort of DJing.