Help me understand how to optimize bass on the Zu Definition Mk IV

David, it's totally reasonable not to feel so challenged you can't get it right. I'm envious of those Def4s owners who got things right on the first day, kicked back and relaxed.

Indeed, I've been running my 4s for just over 6 yrs, and in concert w my analog reinstall coming up trumps, I'm FINALLY properly dialling in my Defs.

For me, they've taken big strides re room position, footers, Duelunds and Lundahls upgrades, power cords, fuses, grounding (Sean installed ground posts for me), balanced pwr to subs.

Updated Lundahls, Gaias footers and careful attention to subs settings and toe in could provide big upsides.

Can you tell me more about the power upgrades you are describing?

I've found a simultaneous benefit and drawback of the high efficiency of these speakers is how much they reveal noise issues in my system, including very minor ground loops. I had been considering star grounding the components prior to acquiring these new Zu's. It would be great to include them in the scheme, if adding the grounding posts is something that could be done while the sub amps are in for upgrades...

On other fronts, I've played around with power cords, without hearing really significant differences. At one point, I had Shunyata cords on my previous Definitions, but wasn't sure they were any different to the Zu Birth cables that came with them. Upgraded fuses have also been difficult to assess real vs. perceived gains. Did you upgrade a fuse inside the sub amps?

Keep in mind, the sub amp is a Class D, with relatively low consumption requirements, and the amp has limited frequency duties in this application. You have far more influential opportunities elsewhere in the system to strive for more objective sound than worrying about the power cord and fuse to each Def4.

Phil

Totally true, Phil, I was just curious where Marc has gone with his power upgrades. I still have some work to do to reduce some background noise in my audio chain, particularly when using my turntable as a source. I agree that the subs are the least of my worries in that regard. I had wondered, however, if the power cords to the Zu's were introducing the possibility of some ground loop hum (heard through the compression tweeter), as they are currently plugged into a different circuit. Solving grounding problems has yielded tremendous gains for me in the past, on both the listening and recording ends of the spectrum. David

Yes, you should solve grounding problems. You're hearing hum through the Radian compression tweet? That's strange. No, the Zu Def power cables aren't introducing ground loop hum. But you probably have induced some ground loops in your system connections, and it's likely your ground points are not all on the same plane. Solutions are always elusive. If the sub amps' power is contributing, it's not the cords, it's having them plugged into a different circuit. By chance, do you have cable TV among the sound sources into your system?

Also, is any portion of your system balanced or running balanced or XLR cables? Mixing Bal with SE can also surface ground problems. What is your analog chain (phono-pre > pre) and is there an SUT in the mix? How many (if any) of your components have ground-lift switches? Do you have any passive components that are not separately grounded? What's your phono cartridge and tonearm, and how closely are they placed to anything else with a substantial power supply?

Just some questions for which answers may narrow your suspects.

Phil