- Joined
- Jul 16, 2016
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9-11-16
I recently purchased a PL-700 Series II because I wanted to upgrade the amps driving my vintage AR-9 (4 ohm)speakers. I had a bi-amp setup using two PL-400 Series I. But, both of these amps seemed to run out of steam at high volume listening levels, so I was seeking more.
The new PL-700 was advertised as having two new PS capacitors upgraded to 40,000 uf combined value. The seller also stated that he had replaced four ‘caps’ with Nichicon on the main driver board. He also repeatedly specified that I mustn’t change any settings of the ‘bias’ as he had it all tuned and it was performing perfectly.
This amp has not had any other changes made to it since new, and allegedly it had sat in a closet for 12 years dormant before he bought it from the original owner.
My experience with PL amps goes back to 1974 when I bought my first PL-400, which lies dead along with 5 other PL-400’s that are all in need of repair for varied reasons.
I also had purchased two refurbished ‘minty’ PL-700’s SeriesII from Ed B. in 2009 and these two run wonderfully and power (four) stacked AR-LST’s at 4 ohms each without ever complaining even after seven hour high volume listening marathons in an air-conditioned house during summer months.
Utilizing a small digital thermometer’s probe located loosely between the transformer and first row of heat-sinks. Room temps being in the range of 73-75 degrees F.
Although I’m using 4 inch fans running at 1800 RPM installed in the dedicated PL fan shrouds on each amp, temps of the amps never go beyond 103F. degrees even when I’m really cranking for hours with strong and powerful rock or classical music. At ‘idle’, amp temps range 85 to 92 degrees with no signal applied and fans going at about 1000RPM. I use variable controls to vary fan speeds accordingly. Each amp individually sits in a 13”X27” open back shelf, so there’s plenty room for air circulation.
Measuring with a sound level meter, I’ll read anywhere from 87db to 91+db on loud peaks while averaging about 74 to 84db for the norm on any given musical piece. This is why I’ve used Phase Linear amps most of my life because I believe in realistic/live sound levels. The room is 12X25X8 for the four stacked AR-LST’s.
O.K., these are some of the particulars with a little history for perspective.
Now, the in-use findings that I have observed with this latest acquisition in the last 7 days are pretty different.
Being a new purchase, I thought it best to put the new amp through its paces. So, after hooking it up to the AR-9’s by itself and not using any bi-amp configuration, I find it running excessively hot.
When cranking it with varied types of music, it’s ranging from 115 to about 125+ degrees. All this is while using a four inch fan in a PL fan shroud at 1800RPM.
Admittedly the second room it’s in is about 2 to 5 degrees warmer than where the other double amps are but, the room is of similar size and the amp sits in an open-back and open sided rack with about 2 inches of free space above its top.
Because of the difference of shelf size and less air circulation and the room being a bit warmer, I could understand amp temperatures being slightly higher, however that’s a bit scary for me and seems excessively high. When I do crank it even higher it does get to about 135F. degrees.
When I contacted the seller/tech, he stated that those temps are within tolerances and that I shouldn’t worry. He went on to state that even if the temps became higher the thermal-circuits would shut down the amp, so I shouldn’t worry.
Speaking for myself, I've never experienced a Phase Linear amp taking care of itself the way brochures back then stated. Mine have always either blown an in line fuse or have taken out tweeters and mids. And with my vintage speakers, I'm not open to that kind of stuff anylonger.
Well, even though I’ve forgotten most of even the very basic of electrical fundamentals that I learned many, many years ago, I still remember that SS components and high heat do not go together very well. This amp still has all of its original “XPL-909” transistors in place (they look perfect) which also strikes a note of personal fear.
So, my reason for posting here is obvious, does anyone have any information to either make me want to get drunk and bury my sorrows, or should I just sit back and listen to more loud music and enjoy myself and not worry?
Are any electrical components wearing down or possibly out of specification? Maybe something else is not correct regarding the bias setting?
FM
I recently purchased a PL-700 Series II because I wanted to upgrade the amps driving my vintage AR-9 (4 ohm)speakers. I had a bi-amp setup using two PL-400 Series I. But, both of these amps seemed to run out of steam at high volume listening levels, so I was seeking more.
The new PL-700 was advertised as having two new PS capacitors upgraded to 40,000 uf combined value. The seller also stated that he had replaced four ‘caps’ with Nichicon on the main driver board. He also repeatedly specified that I mustn’t change any settings of the ‘bias’ as he had it all tuned and it was performing perfectly.
This amp has not had any other changes made to it since new, and allegedly it had sat in a closet for 12 years dormant before he bought it from the original owner.
My experience with PL amps goes back to 1974 when I bought my first PL-400, which lies dead along with 5 other PL-400’s that are all in need of repair for varied reasons.
I also had purchased two refurbished ‘minty’ PL-700’s SeriesII from Ed B. in 2009 and these two run wonderfully and power (four) stacked AR-LST’s at 4 ohms each without ever complaining even after seven hour high volume listening marathons in an air-conditioned house during summer months.
Utilizing a small digital thermometer’s probe located loosely between the transformer and first row of heat-sinks. Room temps being in the range of 73-75 degrees F.
Although I’m using 4 inch fans running at 1800 RPM installed in the dedicated PL fan shrouds on each amp, temps of the amps never go beyond 103F. degrees even when I’m really cranking for hours with strong and powerful rock or classical music. At ‘idle’, amp temps range 85 to 92 degrees with no signal applied and fans going at about 1000RPM. I use variable controls to vary fan speeds accordingly. Each amp individually sits in a 13”X27” open back shelf, so there’s plenty room for air circulation.
Measuring with a sound level meter, I’ll read anywhere from 87db to 91+db on loud peaks while averaging about 74 to 84db for the norm on any given musical piece. This is why I’ve used Phase Linear amps most of my life because I believe in realistic/live sound levels. The room is 12X25X8 for the four stacked AR-LST’s.
O.K., these are some of the particulars with a little history for perspective.
Now, the in-use findings that I have observed with this latest acquisition in the last 7 days are pretty different.
Being a new purchase, I thought it best to put the new amp through its paces. So, after hooking it up to the AR-9’s by itself and not using any bi-amp configuration, I find it running excessively hot.
When cranking it with varied types of music, it’s ranging from 115 to about 125+ degrees. All this is while using a four inch fan in a PL fan shroud at 1800RPM.
Admittedly the second room it’s in is about 2 to 5 degrees warmer than where the other double amps are but, the room is of similar size and the amp sits in an open-back and open sided rack with about 2 inches of free space above its top.
Because of the difference of shelf size and less air circulation and the room being a bit warmer, I could understand amp temperatures being slightly higher, however that’s a bit scary for me and seems excessively high. When I do crank it even higher it does get to about 135F. degrees.
When I contacted the seller/tech, he stated that those temps are within tolerances and that I shouldn’t worry. He went on to state that even if the temps became higher the thermal-circuits would shut down the amp, so I shouldn’t worry.
Speaking for myself, I've never experienced a Phase Linear amp taking care of itself the way brochures back then stated. Mine have always either blown an in line fuse or have taken out tweeters and mids. And with my vintage speakers, I'm not open to that kind of stuff anylonger.
Well, even though I’ve forgotten most of even the very basic of electrical fundamentals that I learned many, many years ago, I still remember that SS components and high heat do not go together very well. This amp still has all of its original “XPL-909” transistors in place (they look perfect) which also strikes a note of personal fear.
So, my reason for posting here is obvious, does anyone have any information to either make me want to get drunk and bury my sorrows, or should I just sit back and listen to more loud music and enjoy myself and not worry?
Are any electrical components wearing down or possibly out of specification? Maybe something else is not correct regarding the bias setting?
FM
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