How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier

350, posted on January 11, 2023 at 17:52:58
Mr Steed Audiophile Posts: 829 Location: NY Joined: May 19, 2012	Specifications. 700. B. Series Two. Power output: 350 watts per channel into 8Ω (stereo) Frequency response: 20Hz to 20kHz. Total harmonic distortion: 0.25%. Damping factor: 1000. Input sensitivity: 1.75V.

Should you be interested in a bit more detail..., posted on January 11, 2023 at 18:30:31
E-Stat Audiophile Posts: 37589 Joined: May 12, 2000 Contributor Since: April 5, 2002	such can be found here.

RE: 350, posted on January 11, 2023 at 18:48:18
JohnKutheRN Audiophile Posts: 529 Location: MO Joined: September 16, 2019	Thank you! Now I want one, to power my Magnapan MGIIIa speakers, someday! John Kuthe...

I had a Phase Linear 400 -- sounded hideous, posted on January 12, 2023 at 04:39:20
Feanor Audiophile Posts: 9858 Location: London, Ontario Joined: June 17, 2003 Contributor Since: March 12, 2004	Sadly I lived with it for years before understanding what a POS it actually was. The 400 embodied are the worst negative virtues of solid-state of its era: harsh, glassy highs and at the same time, veiled. Dmitri Shostakovich

Hey, what happened to all those Mac's you had?, posted on January 12, 2023 at 06:11:48
airtime Audiophile Posts: 11287 Location: Arizona Joined: February 4, 2003	I've heard those amps and for the first time I would say I'd rather have a Mac.

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 12, 2023 at 09:22:02
Hornlover Manufacturer Posts: 2529 Joined: March 8, 2002	Those amps a famous for the power they developed, not for their sound quality. Rather harsh. Work OK in a bi-amp system driving the woofers, but drive the mid-highs with something better, like a Dynaco ST70.

What were you running with it?, posted on January 12, 2023 at 09:28:29
Cougar Audiophile Posts: 4574 Location: SoCal Joined: June 25, 2001	I have had 4 of them and they only sound like that with Ribbons or Planars.

Suggestion , posted on January 12, 2023 at 11:57:04
M3 lover Audiophile Posts: 6600 Location: SW Mich Joined: May 29, 2005 Contributor Since: July 4, 2007	Audition before you buy. There's more to it than simple power. "The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

RE: I had a Phase Linear 400 -- maybe for you, posted on January 12, 2023 at 15:11:52

Barry
Audiophile

Posts: 1001
Location: PA
Joined: November 24, 1999
Contributor
Since: January 18, 2009

Took a little work but this was a very nice amp.

The problem with it and the 700 was the meager capacitance of the power supply. I think the 400 was only 15,000uF per rail- this was the primary reason they blew up when overdriven. Even a good preamp had way more than that.

Add 40K+ per rail and it was a totally different animal I did quite a few more changes.

One of my all time favorites.

RE: 350, posted on January 12, 2023 at 15:15:28
Barry Audiophile Posts: 1001 Location: PA Joined: November 24, 1999 Contributor Since: January 18, 2009	I'd be careful. I think some of the transistors used are no longer made.

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 12, 2023 at 19:07:37

Krav Maga
Audiophile

Posts: 2351
Location: Texas
Joined: October 19, 2017

Here's a link to a pdf of a brochure with specs of Phase Linear products including the 700B.
"All thoughts are prey to some beast" - Bill Callahan

"I'll be your mirror
Reflect what you are" - Lou Reed

"Blind belief in authority is the greatest enemy of truth." - Albert Einstein

https://www.google.com/url?sa=t&source=web&rct=j&url=https:/

I had a few Phase Linear PL-400's series 1..., posted on January 12, 2023 at 19:33:29

Cougar
Audiophile

Posts: 4574
Location: SoCal
Joined: June 25, 2001

and it only had 5,900uF per rail. I put 10,000uF per rail and upgraded all caps, matched the resistors on the Differential Pair for way better DC Offset measurements. I also upgraded all the emitter resistors. Changed the Input RCA's and Output binding post. After doing all that, this was one really nice sounding amp until one of the original output transistors gave way which was the weak link of this amp since they were not matched so the weakest transistor would give out. That's what happened to mine and I had to order some On Semi transistors and it's been great ever since.

I upgraded the PS caps to 10k uF to no effect, posted on January 13, 2023 at 04:20:54
Feanor Audiophile Posts: 9858 Location: London, Ontario Joined: June 17, 2003 Contributor Since: March 12, 2004	The work was done by a very reputable technician who tested the amp an proclaimed it in good shape. However there was no sound improvement. I asked him if all electrolytic capacitors ought to be replace; he said that he didn't think it would be worthwhile. In any case his services were pretty expensive; I wasn't up to doing the mods myself. Dmitri Shostakovich

Most of the time, B&W DM7's, posted on January 13, 2023 at 04:22:17
Feanor Audiophile Posts: 9858 Location: London, Ontario Joined: June 17, 2003 Contributor Since: March 12, 2004	Thing of them as the polar opposite of ribbons. Dmitri Shostakovich

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 13, 2023 at 14:12:46
fstein Audiophile Posts: 2994 Location: fstein Joined: May 18, 2006	Zero if it's on fire

Not even close to being enough, posted on January 17, 2023 at 09:24:44
Barry Audiophile Posts: 1001 Location: PA Joined: November 24, 1999 Contributor Since: January 18, 2009	Most good 200@ 8ohm/400 @ 4ohm watt per channel amps today have 50,000uF per channel. You will hear improvement with even more. With 10K, you can put the amp on a scope and watch the power supply rail voltage sag seriously below spec when you turn up the volume. The transformer is big enough, but the size of the caps was a bad joke.

The 700B was big, crude, a bit dangerous, and not very good sounding - but there are 'solutions', posted on January 18, 2023 at 12:40:35

mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
Since: October 23, 2016

You might want to consider the so-called "White Oak mods", which essentially modernize the rather clunky and somewhat fragile electronics inside the pretty (in a manly way, that is) 700B box with - presumably - much better ones. Folks who "do" PL seem to like the so-called "WOPL" amplifiers. I have no experience myself, so do your homework. Link to White Oak below.

Here's a sample thread on the result of "doing the WOPL mods" to the 700B from AK. Again, I have zero ears-on experience, but it seemed worth mentioning.

The new boss is in town! WOPL-1000

all the best,
mrh

https://www.whiteoakaudio.com/

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 20, 2023 at 10:39:04
illenema Audiophile Posts: 55 Joined: October 31, 2003	I had the original 700B and the 700B SeriesII. Clipped at 600 a side 8 ohm. Never blew up on me.

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 20, 2023 at 11:41:33
marlin Audiophile Posts: 154 Location: Sandy, Oregon Joined: November 20, 2012	My 700B was my daily driver up until about two weeks ago. Never had any problems out side of meter bulbs going out. Thought about doing the White Oak mods but but opted to go modern instead I am the second owner as far as I know. Prior to me, the dealer when being serviced clocked it at 425 W/ch IIRC. Guess I am one of the lucky ones. Marlin Without music what is there?

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on January 22, 2023 at 09:03:22
JerryS Reviewer Posts: 2026 Joined: February 24, 2001	1 horsepower, 745 Watts

I just doubled it cause..., posted on January 22, 2023 at 10:22:16
Cougar Audiophile Posts: 4574 Location: SoCal Joined: June 25, 2001	anything bigger would not have fit in the chassis at the time I did this. Now, it will be a different story can easily get up to 30,000uF into the chassis. What made it hard was the Voltage rating was higher than other amps and so it used a bigger sized cap.

RE: How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier, posted on February 3, 2023 at 12:38:22
pictureguy Audiophile Posts: 22597 Location: SoCal Joined: October 19, 2008	Wasn't it the 400 that has the 'reputation'? I don't know that I ever heard bad stuff about the larger brother.... Too much is never enough

Yes, it was the PL-400 that had some issues...., posted on February 4, 2023 at 11:57:18

Cougar
Audiophile

Posts: 4574
Location: SoCal
Joined: June 25, 2001

with output transistors not being properly matched. So when the amp was connected to loads that dipped below recommended loads or played at high volumes the weakest link in the transistor output chain would go. I only read a few posts about this. The Pl-400 used a Quasi Complimentary N Channel output stage. Funny thing, cause my Edge M8 power amp has the same type of output stage as well and sounds great! It's output stage has Toshiba 2SC3281 Output transistors

I have two Pl-400's series 1 and rebuilt them and per advice from a former member here, with On Semi MJ 15024's for driver and output transistors. After that replacement the amps have worked flawlessly.

I have recently pickup the upgrade kits offered online that will convert the driver PCB's to current product transistor, caps, resistors, and connectors. Just haven't had time to work on the PL-400's yet.

Amp/Preamp Asylum

How many watts pe channel for a Phase Linear 700B Stereo Power Amplifier

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