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Review: Phase Linear 700b Amplifier

Category: Amplifiers

I have on a mission to find a clean natural sounding amp to power the ALIII. The ribbon drivers present a very difficult load. I found a 700 b rebuilt by an electrical engineering professor who does it as a hobby. WOW. So this a a mint 700b and maybe upgraded slightly from original. Without going into long analysis of music this amp has massive power and transparency and it does sound more tube than solid state unless you drive it to clipping. The closest thing I have heard that compares is the Boulder or Levinson amps which are thousands of dollars. In 1978 money this amp approached the $5000.00 price tag. Anyway I only paid $500 and what a steal. It is like buying a Ferrari for the price of a Chevy Cavalier. And being vintage it will go up in value. I would avoid overdriving. However, if this amp was used on efficient speakers of the cone design one would be operating at about 5-10 watts giving you massive reserves and low distortion. This amp would probably blow a high efficiency speaker. I assure you that you will be listening to all your music all over again. This amp proves that solid state does not have to sound harsh.

Associated gear
Carver ALIII speakers
Carver CT17 preamp

Similar products
Audio Research, Krell/ Mark Levinson
crawfojb
zargon's avatar
zargon
453 posts
 
You will find some interesting reading about these amps on this Official Phase Linear web site. Dean is the last PL factory trained technician still doing repairs.

http://www.vintagephase.com/

This amp is indeed a powerhouse, however, proceed with caution. These amps were well known to short out and take the speaker drivers out with them.
crawfojb OP
13 posts
 
This amp when refurbished is an excellent vintage performer but is not designed to handle planer loads which can drop below 2 ohms. Use this only on conventional 8 ohm speakers otherwise the amp will overheat.
porziob
316 posts
 
All phase Linears ran hot. I sold these amps in the early 70`s. Put a fan on it, & it`ll drive low efficiency 4 ohm spkrs. all day & night long. Might, & I`ll hedge here, even deal with 2 ohm dips that aren`t that common.
whitefalcon44
3 posts
 
I have a Series II, and have had no trouble with it. It does make some pops when turned off. It really opens up the speakers. This was a legendary amp in the seventies. For $400.00 at the pawn shop, it was a steal.
jnewman2-4604
1 posts
 
I still have the series 1. It ran hot and I installed fans in the back to keep it cool. It destroyed many a great speaker-- and I would not have had it any other way-- Nothing today comes close.
John
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