How does the Phase Linear 400 compare?

Sean.
I thought your description of Carver products was very accurate. Bob Carver was a genius and did things in a very creative way that most manufacturers did not do. I purchased a C-4000 around 1985 for $ 800.00 and I thought it sounded awesome with Pink Floyd the wall.  The Sonic Holography blew me away.  But after listening for a while I found it fatiguing and did not sound right (it did not reproduce instruments to my ears in a pleasing way).  I also purchased one of those Rubicks Cube amps used and was amazed at the power. I blew it up in a short amount of time and traded it off  for  an Audio Research SP 9  and Bryston 4B.    I never really noticed much of a difference with the Peak Unlimiter and Auto Correlator on the preamp. However I will never forget that wide unbelievably large sound stage of the Carver Preamp but it only sounded good with a few records that I owned.

jim55379,
I have a Phase Linear 4000 series one preamp (I used to have a 4000 series two as well).  It has the widest soundstage I’ve ever heard. The deepest too.  It also excels in detail and dynamics like no other and is whisper quiet.  But I can’t listen to it for more then a couple of hours.  The midrange seems hard and bitting after a while to me.  Not everyone just me.  It’s pristine, and I can’t seem to part with it, even thought it spends most of its life in its original box.  Years ago, it was my favorite preamp, but my taste have changed.  I enjoy my ancient marantz for preamp duties, that or my Sansui 9090db which seems to do everything just right.

Oh, and I had two Carver M-400’s strapped in mono giving 500wpc into 8 ohms.  They were pretty remarkable, but I never thought they were as smooth as the Phase Linear 400, which I’ve also kept over the years.  It actually works well with my marantz 7c.  

Carver’s tube amps are incredible.  Wouldn’t mind a pair of those, any of them.

The Phase Linear 400 ii was a low transient intermodulation distortion (TIM) amplifier. The old post claiming it was a high TIM amplifier is likely based on opinions that were floated against this amplifier because it was priced far below higher end amplifiers. It blew my McIntosh MC2200 out of the water sonically and I'm a long time McIntosh owner and still am along with Conrad Johnson, Modwright and Sonic Frontiers.

Transient intermodulation distortion is generally caused when the forward path of a feedback loop is too slow to make the feedback circuit track the input signal under true transient music conditions. Poor slew rate and or an open loop transfer function can cause TIM.

The Phase Linear 400 ii was designed well after the discovery of TIM and Carver avoided the problem. A properly biased, in spec Phase Linear 400 ii has a very high dampening factor, wide bandwidth and a fast slew rate. They are sonically very accurate and transparent amplifiers that create a very deep sound stage with lots of low level detail.

Now the negatives. The amplifier was built to sound very good at a price point. It lacked any real DC protection for speakers, if the power supply capacitors failed. It also really needed more heat sink surface area and many an audiophile cranked up the bias to true AB1 and accordingly there were some serious failures of these amps that also took out speaker systems hence the nick name, "Flame Linear".

With good caps, upgraded outputs (say MJ15024s), proper bias setting and a DC protection relay added these are still excellent amplifiers and these improvements are pretty easy and low cost to implement.

i bought a new pl400 back in 1973. cheapest power amp back then with 200 watts per chanell!!! 

What does this amp have in common with the pyramids? Its ancient history.