My 3's, 4's and 6's all ran at about the same temp give or take. The 4's should have been "warmer" in theory. All of these amps idle at about 115* - 120* or so and climb slightly from there when "gettin' it". Maybe my bias is up a bit on the "A/B" models. Should probably check into that.
The 3's actually sound slightly sweeter and airier ( but a little leaner ) to me than the 4's. Then again, my 3's were modified by Jon Soderberg of Vintage Amp. The 6's retain most of the sonics of the 4's but offer greater headroom and "oomph" in my opinion. Since most of my speakers are both low impedance and low efficiency, the bigger amps are a little more suitable to my situation. The 4's are QUITE beefy for "50 watters" though.
I ended up selling the 4's and kept a pair of 3's and a pair of 6's for use in a pretty big system that i'm working on. All four of these amps will be getting "tweaked" even more too far down the road.
My 1A actually ran noticeably cooler than all of these amps. That is, even though it was supposed to be "Class A" like the 4's. While it was noticeably lean sounding ( moreso than the 3's ), it also lacked the air and "sweetness" that i hear in the other Forte' amps. That is not to say that it is a bad amp, only that it was not what "I" was looking for. Who knows, maybe that one was slightly out of whack in terms of bias, caps partially drying up, etc.... Either way, the guy that got it absolutely loves it. His speakers were somewhat warm and he lives in an apartment, so he did not need a lot of "oomph" and the lean sonics complimented the rest of the system. A match made in heaven as far as he's concerned.
As to Brian's amp, it might have simply been a "lemon" or didn't blend well with the rest of his gear and various cabling. You would think that a pre / power amp combo from the same company would blend well together, but not necessarily so. Like anything else, it is all about system synergy and personal preference. That is why so many of us stress "in-home auditions". What floats your boat with your other gear might not float mine and vice-versa. Glad that he did find something that was to his liking though.
I've used one of my Forte's as a "loaner" on several occassions. Everyone that has used it has commented on how "sweet" it sounded. This with SS, or tube pre's including one guy running a passive. Somehow, everyone keeps using the same description ("very sweet sounding") of these amps without any coaxing or previous knowledge of them. The fact that they picked that single phrase, out of all of the audiophile terminology to choose from, tells me that there must be something to it.
As a point of interest, one of the 6's that i picked up had been previously repaired. The owner was not aware of this when he bought it. As such, he was not that thrilled with the amp, etc... and sold it to me. Once i got it home, I found the repair work and inspected the rest of the amp. The labor was done pretty poorly and using substandard parts. The amp ran much better once it was straightened out.
As mentioned, these amps sound MUCH better in terms of air, detail, spaciousness, etc.. after they've been on for hours and hours. If someone is turning these off and on as needed, they will never hear what they are fully capable of. I leave them on ALL the time for best results. Turning them off for an extended period of time "flattens" them out quite noticeably in my opinion. 24 - 36 hours after turn on, they should be pretty solid. I think that they sound best after about 3 days of continuous power though. All "high bias" amps appear to operate similarly to me. Amps that typically run "cool" or use digital / switching supplies don't seem to benefit from "continual on" nearly as much. Sean
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