Question on PrimaLuna EVO 400 Amp: Fully Balanced (Differential), or No?


I've just taken delivery of new PrimaLuna (separates) EVO 400 amp & pre, and need some informed advice in re: hooking up my single REL S/812 sub. The REL manual shows different connection schemes for Differential (fully balanced), as opposed to standard.  I do have balanced (XLR) interconnects from DAC to pre, and from pre to amp, and there's a switch on the back to select for XLR connections, which I've engaged.

I've checked the PrimaLuna owner's manual, and searched online, but I can't find any indication of whether the EVO 400 amp is "Standard" or "Differential" (fully balanced). Does anyone know for sure? The REL cable has 3 terminations, and in standard amps, the black ground wire is connected, whereas in Differential, it hangs loose, or "floats."  Any insight on this would be greatly appreciated.

128x128zmann007

And yet another blink in Geological Time goes by, when I finally respond by saying...

 

The Floyd is still going strong, and I've rolled the tubes to some very sweet NOS 60s & 70s RCA tubes, which has taken it to a whole new level. That, and the more recent addition of a pair of YG Carmel 3 speakers, has changed things up in the best possible way. For anyone considering a speaker upgrade or change, I'd suggest checking out the YGs, and perhaps a pair of Stenheim Alumine Two.Fives. We have the latter at Alma Music and Audio in Sterling, VA, where we're also authorized YG resellers. The YGs are a bit more detailed, but I have to say, the Stenheims have a charm all their own, and sound perhaps a bit more "organic." Both have the distinct advantage of solid aluminum enclosures and an incredible marriage of materials & engineering; it really comes down to what sounds best to your ears. To me, they're first cousins, and either pair will take an already solid mid- to upper-line system right over the top. Of course, the Hana Umami Red I added earlier this year has certainly brought me to a place where I'm starting to wonder how much further I really need to go. I think a DAC (perhaps Bricasti M1 Series 2) is next, but will have to wait 'till my savings catch up a bit.  So with apologies for the long stretches between the [binding] posts, I bid you happy listening!

@zmann007 My dealer has that EVO 300 Hybrid. I've listened to it for many hours on multiple speakers and really, really enjoy it.  Congrats on the purchase!

I know this is quite a while later, but I thought I'd follow up & close the loop. I ended up returning both the amp & pre to Upscale, who were very gracious about taking them back. They tested both, and could find nothing wrong. Before sending them back, I hired an electrician to go over our entire TH; he, too, could find nothing amiss. I did order a PL EVO 300 Integrated Hybrid "Floyd" from Upscale, and have been very (very) happy with it. All's well that ends well....

If the amplifier employs AC filaments for the voltage amplifier tubes, a cathode/filament short in a tube could cause that.

Well, it appears I spoke too soon. The EVO 400 amp & pre developed a nasty ground loop hum / buzz that no amount of troubleshooting could cure. Indeed, the steady 20 - 25 dB bug zapper sound persisted, even after every source and peripheral was unplugged, including the sub. As soon as the amp came out of 'safe' mode, there it was.  Anyone experience anything similar?  Figure out a cure (short of installing a full solar array & getting off the grid)? I sent 'em back today, and am rolling the dice that I'll have better luck with the hybrid integrated EVO 300 Floyd. Fingers crossed....

Confirming the above -- I heard back from REL yesterday, after they had reached out to the PrimaLuna Mothership.  The EVO 400 is a standard (not Differential) amp, and so -- at least in single sub, non-monoblock (stereo) configurations, the black ground wire is attached to (either) negative / ground binder post.  The REL does want the 8 ohm posts, though; Upscale was quire clear on that, and it seems to be working fine.

 

 

while the evo 400s have XLR connectors, they are not fully differential designs. 

still a traditional design. 

a pretty easy way to measure it compare the black speaker output terminals reference to ground. if its at same potential cannot be fully differential. 

 

I have the Evo 300 power amp and I've connected my REL 212SE as shown on the REL website:
https://relsupport.zendesk.com/hc/en-us/articles/360001493114-Tube-Amp-Connection-Methods

Although the 300 and 400 have XLR inputs I don't believe they are dual differential designs internally.

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