Krell FPB 600 or 400cx?

http://www.stereophile.com/content/krell-full-power-balanced-600-power-amplifier-measurements

According to this Stereophile test results, the Krell FPB600 almost doubled in power going from an 8 Ohm to 4 Ohm load, and then again going down to a 2 Ohm load.

There was no indication looking at the test results to support the claim that this was a bridged amplifier. To the contrary, it said that it could drive any load of any impedance.

And the only reason it didn't quite double into 4 Ohms was because the line voltage began to sag.

I completely agree and know of this also, where you are going to see it in the FPB600-700 is driving say Soundlabs or Apogee speakers that are living below 2 ohms most of the time. There is no lack of power with this amp and don't read too much into that difference. It's only in the most extreme loads you would experience anything at all. Mr Dan designed all these amps to be pure voltage source amps, bridged or not, if they are bridged it must be in parallel anyways, I understand it's basically two FPB300's. If they were bridged in series the power would be 1200+ into 8 ohms and that would be restricting the amperage. In order to be a constant voltage source regardless of the load, the current must be unrestricted, this is why the wattage doubles with every halving of load. I'm not trying in anyway to knock any FPB amp, just understand their differences and I do not currently own a FPB600 only the 300 stereo amp and my mono's.

I just ordered a pair of FPB750MCX Mono's should be here in a week or two, can't wait to listen to my first X amps in my own system.

On another note. My son and I were doing the annual cleaning of our equipment and all the connectors. We remove all the panels and clean the inards and boards inside along with all the connectors. So we finished the KRC3 and my bedroom S300i and decided to try something which kind of relates to this thread. We put the S300i in theater bypass mode and ran it directly from the KRC3 with all the silver cabling I normally use. WOW what a difference, I never liked the veiled lethargic sound of the S300i but running in theater mode is a whole different ball game! It must completely bypass the horrible preamp section and route the balanced input directly to the amp? It sounds great not like a BIG FPB's but hey it's a $2500 amp and it sounds tight, SWEET and powerful. Gone is the top-end and mid-range shouting and raspy treble. It sounded much more like the KRC3 itself now, very musical, natural. All of the sudden it has a sound-stage and a good size one at that, depth, it made the 801N's bass sound tight and punchy. It's not the same Majesty and effortlessness you get from the FPB650MC's but hey I could listen and love this all day, and we did.

Looking for a true audiophile bargain, get a good preamp and run the S300i as an amp only, direct in theater mode, you will be glad you did. Granted it too is plugged into a PS Audio P-1200 @117 volts @ 90 hz but damn it really sounds great, it's just the preamp section that sounds so nasty.

Now do I buy a Krell EVO 202 or help my son pay his tickets off?

Rob

Sorry I meant 2 Ohms.

Over the last two weekends I have spent some time listening to some McIntosh amps and pre-amps. I've been curious to learn more about the comparison between the Mac's, Pass amps and Krell. I'm definitely more familiar with and more used to the Krell sound. That being said I get it now why some like the Mac's so much, the mid-range is great and very articulate. The Mac mid-range to me sounded very alive and natural, impressively real and musical. The top end was extended pretty well but not as sweet as I was expecting and a bit brighter than my on Krell's, I have not listened to them as much yet but the Pass amps seem to be the treble masters, very sweet and yet nothing is missing. For the BASS, I noticed right way that the Bass was not as articulate as I'm used to, what I liked in the mid-range did not extend into the bass. I could distinguish the separate bass notes but it was like there was a blanket between me and the woofers. Both the Pass and Krell were easily more articulate, crisp and powerful in the bass and the krell seemed like it could add a few lower notes.

I'm happy with my little Krell world except for them kicking Dan out. But the Mac amps do look nice and run cool and probably do not consume near the power of the Pass or Krell amps? All the amps I heard so far are great, so don't get me wrong here. Personal taste, I like the Pass amps a lot they really have a very sophisticated sound but as far as living together, they are about the same as the Krells. The Krells seem very honest to me and extremely controlling of the speakers themselves, like the Pass amps they arn't bad at anything but a little different from the Pass amps. I'm still happy with the Krells but I do admire the Mac mid-range and the mid-range and treble of the Pass amps. Imaging, depth and height the Pass amps are more clear to me that the Mac's, Both the Pass and Krell can have a huge soundstage that is more pinpoint accurate then the MAC's but I'm afraid I'm exaggerating too much the difference. Drum sets, Piano's and singers were mainly what I was listening to on all three so far for imaging, the Mac had slightly bigger images and kind of blurred the drum set together a bit, with the Pass and Krell amps I could point to each individual drum or cymbal. On the Pass and Krell amps I could not only hear the singer like I could on the Mac but I could hear which way they were projecting their voices and if the were walking around. My wife is a harsher critic, she did not like the Mac amps as much because of the bass mainly.

Just some completely subjective thoughts here, I wish I could hear the Pass amps some more they are very nice.

Rob