Hi, I'm a new (and very pleased) Sensation owner and new to the forum. I've been glad to read what people have had to say about various battery options.
I've found a battery solution that works well for me and saved me buying a battery ps for $250. I had a spare APC brand UPS (1100VA) which uses two 12v 12ah SLA batteries (pretty common) in series to provide 120v a.c. power for a pc in the event of a power failure. Being very cautious with the Sensation, I first removed the two 12v batteries, wired them to a coaxial barrel type power connector, verified the polarity, and ran the Sensation directly from the batteries alone with no attached charger....FANTASTIC! Everything that people are saying about the improved sound with the batteries is accurate and easily hearable...big improvement in an already great amp!
.
Then I reinstalled the two batteries and spliced connections from the positive and negative battery wires to a coaxial female power connector and mounted that on the front of the ups. Now I can plug the Sensation directly to the ups batteries. As this is a spare ups, I don't need the inverter to backup a pc, so I leave the ups turned off. However the charging circuit is on whenever the ups is plugged in to maintain the batteries (@ 27.4 v). Using a good mulitmeter I've measured an amount of rms 120hz a.c (rectified 60hz) equal to about .1 to 1% of the d.c voltage. This amount of a.c. noise is not hearable on my 90db speakers at normal listening levels, but is definitely hearable (and annoying) at loud listening levels. So an easy solution to this was to plug the ups into a power strip and switch it off (thus shutting off the charging circuit) when I want to listen to the Sensation. Then switch it back on to charge the batteries (overnight for example). Additionally the ups has a pass through on the back which can be unplugged to completely disconnect the batteries from the inverter/charger cirucits (but disconnecting the batteries completely doesn't make any difference I can hear as long as the power strip is switched off). Voila, a nice battery ps without the extra dollar outlay.
So this seems to have worked out very well, but I do have some questions. I don't have any technical specs about the APC charging circuit and what protocol it uses to charge the batteries. So I don't know if or how the charger may be running when I have the Sensation on while the charging circuit is on. And I don't have any information about how clean or dirty it is when charging a mostly discharged battery. If anyone has any thoughts on this or other aspects of this project, I'd love to hear from you.
Maybe J.T. or some of you with p.s. expertise could comment on the following:
Does the small amount of rectified a.c I measured present any threat to the Sensation?
Is there an amount of rectified a.c. which would present a treat to the Sensation (as long as it's under 30v)?
Presumably the protection circuit would do its job if it found something it doesn't like about the power input?
Thanks for any feedback. Cheers
