Hi Howard. Just found HFA; full of useful stuff. I am interested in the differences between the electret and mains powered energisers. I have a pair of Stax headphones labelled "New" SR3 which originally (when I bought them in 1975) came with an SRD-5 energiser. The SRD-5 (which is mains powered) was changed for an SRD-6 (which is not mains powered, although it doesn't say "SB")
STAX were somewhat sloppy when it came to marking the type of power used in some of their energisers. In my office I use an SRD-6 which is not mains powered but is not marked ‘SB” (self-bias) either. Ho hum.
Now then, in my office system I use the SRX-Mk3 earspeakers. Both these and the SRD-6 these are quite old and yet have never given a moment’s problem. Curiously, this modest combination of SRD-6 and SRX Mk3 produces a sound characteristic that I can’t quite achieve with any modern STAX combination. There is a colouration with this old combination. It isn’t as neutral as say a 4040 II or Omega-2, but it sure is exciting. However ……
Using that SRD-6 with other earspeakers from that era, I’ve not been able to quite recreate that sound. I have no explanation for this.
In summary then, I cannot for certain say that all non-mains energisers are per-se ‘better’ than all mains-driven energisers. Different does not always mean better whereas better must always mean different! Moreover I cannot categorically state that ‘SB’ is better than non SB. It’s a suck-it-and-see situation. Three points to bear in mind:
The stark reality is that there are no replacement boards for the SRD-5. Board repairs can only (and I know this for a certain fact because of work on my STAX SRA-12S) can only be done back at STAX HQ in Japan. The cost of 2-way transport alone makes this unrealistic. So, I guess your best bet is to buy a replacement dirt-cheap on eBay.