new BHK 250 user


#1

I just got my BHK 250 yesterday and noticed that it is really hot to touch on the front and both sides on the headsink even it is idle. It is sitting in a rack and both front and back are opened. Is that normal? Thx!


#2

How much space to the shelf above? I assume the sides are closed; how much space between the heatsinks and the sidewalls? It seems like you may have an issue. Paul can probably tell you how hot it can run before its lifespan is shortened or other problems develop.


#3

Well, I hope it’s normal as I find mine to be hot (or at least really, really warm) even when not running. My rack is open on all sides and there is at least 6" clearance on top. I can put and leave my hand on the top, front and sides without any issue, so it’s not “burning” hot but it’s still hot. When running, it’s hotter but I can still leave my hand on it without any issue.

I find the BHK pre-amp to be the same way. It might be a bit hotter all around than what the BHK amp is. It sits on top of the Directstream and heats up the Directstream as well.


#4

Actually it is all opened around the amp, however, there is not much space on top (please see picture). When it is playing, the front is about 109F and 120F on the heatsink. Room temp is about 84F. Is that normal? I am not so sure. Did I get a defect unit? What temp do you guys get on your BHK 250? Thx for the help!IMG_2292.JPG


#5

This sounds normal to me, especially given the ambient temperature.


#6
a25105 said I just got my BHK 250 yesterday and noticed that it is really hot to touch on the front and both sides on the headsink even it is idle. It is sitting in a rack and both front and back are opened. Is that normal? Thx!
That sounds normal. The amp absolutely runs hot, it's what makes it one of the best sounding amplifiers around. There should be a noticeable difference in heat between standby and operate - perhaps 25% or so. But from what you've siad and shown, I'd say it's normal.

How’s it sounding?


#7

Thank you so much Paul! So glad to hear from you. I was so worried that I turned it off (not standby) last night. The difference between standby and operate is about 6F. It sounds pretty good after the first 24 hrs break in. Paul, is it safe to leave it on standby 24/7? The amp will be running in over 100F constantly, I am just worried that it will stop working after a few months. Please correct me if I am wrong. Thanks again! Really appreciate the help.


#8
Paul McGowan said The amp absolutely runs hot, it's what makes it one of the best sounding amplifiers around.
Paul,

This statement has me curious. I know very little about the technicalities of amp design. I do understand that the BHK is a powerful amp with lots of juice at its disposal to drive speakers; of course, when you put in a lot of power a lot of heat has to be dissipated. Is there anything beyond that basic fact behind your statement about why the BHK sounds so good? (And it does – audio buddy came over last weekend and was very impressed!).


#9
a25105 said The difference between standby and operate is about 6F.
With my BHK the difference between the two modes seems to be considerably more than 6°.

Which brings up a question: last night I wanted to measure the temperature but didn’t know what to use. All I had was a thermometer designed to measure ordinary room temperature. I have no idea if it is accurate above 100° or so and also didn’t want to put its plastic housing over the hot heatsinks. What is the right instrument for this?


#10

a25105, it is recommended that the BHK amps be left in standby rather than turned off at the back in normal use. They sound better that way. Much of the circuitry (other than the tubes) remains powered up when in standby which eliminates the need for a more protracted warm-up period prior to use. It is generally recommended that most sold state equipment be either left on or in standby (if that is an option) for best sound. Also, the power surges that occur when equipment is powered off and on put their own strain on the components so leaving things on standby eliminates that. The BHKs are designed to be operated this way so I would not worry about the heat.


#11

Thx Stevem2! Yours probably runs cooler since you are in the east coast:) I am just not used to having a amp that runs this hot, my old Parasound Halo Intergrated doesn’t do that. But of course I am not comparing apple to apple, the BHK 250 is a beast compare to the Parasound. BTW, I always put the Parasound on standby too. So I guess I should not worry anymore since both Paul and yourself confirmed this is normal. I wonder how hot yours run in the east coast just for a reference.


#12

Sorry but I don’t have a thermometer that would work. Like Murrayb, mine does get warm but I can put my hand on the heat sink comfortably. My rack is open on all four sides and I have 4-5" of space above the amp so mine may be a bit better ventilated than yours. You should be fine (but you do have a three-year warranty, just in case).


#13

Not sure what had happened but my BHK 250 is running a lot cooler after turning it off from the back last night (less than 24 hrs). Room temp is about 80F, the front of the amp is now 99F and the heatsink area is 113F when playing music. Nothing has changed other than turning off completely before going to bed last night. Amazing!


#14
a25105 said Thank you so much Paul! So glad to hear from you. I was so worried that I turned it off (not standby) last night. The difference between standby and operate is about 6F. It sounds pretty good after the first 24 hrs break in. Paul, is it safe to leave it on standby 24/7? The amp will be running in over 100F constantly, I am just worried that it will stop working after a few months. Please correct me if I am wrong. Thanks again! Really appreciate the help.
Yes, there's every reason to leave it in standby 24/7 because that's what it was designed to do and it appreciates the long term running in standby. I wouldn't leave the tubes on for more time than needed, but standby, yes. I leave mine on 24/7 and you'll get years and years of pleasure running it like that.

#15
magister said
Paul McGowan said The amp absolutely runs hot, it's what makes it one of the best sounding amplifiers around.

Paul,

This statement has me curious. I know very little about the technicalities of amp design. I do understand that the BHK is a powerful amp with lots of juice at its disposal to drive speakers; of course, when you put in a lot of power a lot of heat has to be dissipated. Is there anything beyond that basic fact behind your statement about why the BHK sounds so good? (And it does – audio buddy came over last weekend and was very impressed!).


Oh, sorry. The heat matters because it’s all in the way Bascom designed the output MOSFET stages. As you know, they are “one-sex” devices, meaning all N-channel MOSFETs and to get a full signal though this unique arrangement (where normally you’d be using complimentary N and P to handle the full signal) he needs to run them pretty hot. So, this is a roundabout explanation of why it runs hot. If he had gone with traditional P and N channel devices, that would be much more efficient and the amp would run cooler - of course, it wouldn’t sound as good.

#16

Thank you Paul. I do remember discussion of N and P MOSFETs but didn’t understand that using all same-sex devices makes the amp run hotter.


#17
magister said Thank you Paul. I do remember discussion of N and P MOSFETs but didn't understand that using all same-sex devices makes the amp run hotter.
It doesn't but in order to get the linearity he needs, that's when he cranks up the juice.