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Parasound JC-1 Heat Dissipation

I am looking at purchasing a pair of Parasound JC-1 monoblocks based on the excellent feedback both here and other places. After a flurry of upgrades this year, the power amplifier is the next piece of equipment to upgrade. I have made the decision to stick with solid state since I like keeping my system powered up at all times and the Wilson Benesch loudspeakers like lots of power.

My current system:
- TRL Marantz SA-14 SACD player
- Conrad-Johnson 17LS tube preamplifier, Amperex Holland 60s tubes
- Rotel RMB-1095 5X200W multichannel power amplifier
- Wilson Benesch Discovery loudspeakers

My only concern with the JC-1s is the amount of heat generated since they run the first 25/10 watts in Class A mode and consume 250W in idle mode. This is of concern especially during the summer months.

My audio room is sealed, 16.5ft X 12.5ft X 8ft, and is located on the main floor of my house.

Also wondering if I can reduce heat dissipation if I set the bias switch to low (10W Class A) and only switch it to high during listening sessions. If I do this, does it take time to warm up to fully take advantage of 25W potential?

Also if I have a fan blowing on the power amplifiers outside of listening sessions, is this of any use?

Any feedback from others who have a pair of JC-1s in a similar room is appreciated.

Also the match between the JC-1s and the C-J preamplifier which only has unbalanced output.
shuang
11 responses Add your response
swampwalker's avatar
swampwalker
5,138 posts
 
I can only comment on one thing. The fan will blow the heat around in a sealed room, keeping the amps slightly cooler and the room slightly warmer. I would imagine that with bias set lower then the heat dissipation btwn listening would be lower but not sure about warm up to the full 25w. My GUESS is that there would not be much of a warm up time, but then again I am not so sure about leaving a Class A amp on all the time, since it not only is expensive (6 kwh per day per amp at idle) and uncomfortable, but would surely result in faster degradation of internal parts due to constant high heat envt. Just my $0.02. YMMV
rhyno's avatar
rhyno
649 posts
 
my room is slightly smaller than yours, and you'll likely find as i that any amp that throws off heat (the JC1s do, esp in high bias) will heat up the room to an uncomfortable degree in the summer.

JC1s are very nice amps as well, and i could live with them if i could live w/ the heat---low bias might work, but i wasn't about to try and fail.

solution i arrived at: macintosh 501s. ice cold 24/7 and great sound.

rhyno
porziob
316 posts
 
Get a life or a different amp. You should know what to expect with a class A amp. You`re a tiresome whiner. If rain water was wine, you`d still find reason to whine.
Ag insider logo xs@2x
dlshifi
41 posts
 
I owned the JC-1 monos for one summer and used them in a room 16x26x8 (a bit more than twice the volume of yours). Left them on all the time, in the lower bias setting. They sounded great, but I couldn't live with the heat. I even bought a cheap air conditioner to cool the room when I wasn't around, but that only added to the inconvenience. It only took a short time (10 min to an hour, depending on my imagination that day) to hear the effects of the higher bias setting, but I rarely used it because of the added heat. I wanted to keep them to use as winter amps, but I found that the Belles 350A monos did a nice job and ran cool to the touch. Different sound, though. If you want the warm transparency (not an easy-to-find combination) of the JC-1 monos in a smallish, sealed room, plan on listening in your underwear.
rhyno's avatar
rhyno
649 posts
 
belles 350a ref ran hot in my room. sold it before getting the macs

rhyno
bignerd100
515 posts
 
IF you are on a crawl-space simply install a separate small AC unit outside with vents coming up under each amp. Master Handbook of Acoustics will give you ideal duct dimensions if you want to get supper anal. Sure it won't be cheap but look at what you already have in gear.
hiend312cdfe
22 posts
 
My plinius Sa250IV runs in class AB and is left on all the time. very cool, It has switchable class A on the panel, boy does cook then, Then your done for the day, switch the class A off switch in standby, and forget about her.
shuang OP
21 posts
 
Thanks for the input. Sounds like I will have to pass on the JC-1s given my room size.
jayctoy's avatar
jayctoy
4,040 posts
 
Porziob you are the one who whine and drink the wine.
You did not contribute a thing.You get a life.
Shuang question is legitimate,He is concern about the
heat.Dlshifi make a good point because the JC1 do
generate heat.Shuang Plinius 250 is a good choice too.
lkdog
417 posts
 
Shuang-

I auditioned the JC-1's with the TRL SA 14 and they were a good match.
Maybe you could consider the little brother the Parasound 3500.
Good luck.
shuang OP
21 posts
 
The Plinius SA-250 looks like a good unit but it also has a class A mode.

However won't it have the same problem as the Parasound JC-1s? Since it runs in Class A mode to sound its very best.

Is it practical to leave it in AB mode then switch to class A mode for critical listening. Once in class A mode, how quickly will it heat up the room?

From the Plinius manual.

BIAS A: This position provides a true Class A bias to the output stage therefore ensuring the optimum performance of the amplifier during all listening events. Class A amplifiers run hotter than Class AB amplifiers, hence our specially designed and distinctive heat sinks. Operating the amplifier in BIAS A necessitates two precautions that should be observed.

1. On switching to BIAS A, the temperature of the amplifier will quickly increase and the amplifier will become quite hot. Once again we remind you to ensure that you have left adequate space around the amplifier for ventilation. Ensure that no objects are resting on the amplifier and check that the heat sink (cooling fins) are not obstructed in any way.

2. The current required from the mains supply in BIAS A is approximately 1,000 watts, similar to a small electric heater. The amplifier should not be connected to a wall outlet that is shared with other heavy current appliances such as heaters or electric motors.
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