Amp cooling: Necessary, or not?

[Doc Mark]

Greetings, Friends,

As I near the point where I will be experimenting with 2, 3, and 4-way JBL speaker systems, I plan on using an electronic crossover that will allow me to separately amplify all of the above systems. For amps I have two Harman Kardon HK870's, @100wpc into 8 ohms; two Crown DC300A's, at around 175 wpc into 8 ohms, or, around 610 wpc (bridged-mono) into 8 ohms; plus, I have the 65 wpc amp (into 8 ohms) that resides in our Harman Kardon AVR20, receiver. So, at least for now, I believe that our amp situation is pretty well covered, even for a 4-way, electronically crossed over system.

However, with all those amps working away, the thought crossed my mind that maybe, just maybe, they might need a little help staying nice and cool in operation. What say you, Folks? Do I need to install some sort of ventilating fan in the area where these amps will reside and work? If so, what would work well, without adding a lot of noise to the system? IN truth, due to living in a nice, quiet mountain village, this system will very probably not get worked too hard, as our L300's are very efficient, and the combo 4333's will also be efficient enough to take great advantage of all those amplifiers. So, in the end, the system may still run fairly cool, just as it has as a single amp, full range system. Thanks, very much, for any and all suggestions! Take care, and God Bless!

Every Good Wish,
Doc

[BMWCCA]

If you're racking the Crowns, allow one rack-unit space (1.75") between them and the next piece of equipment and they should be fine if there's sufficient back space. Get yourself some single-space rack screen/vents to fill the gap.

If they're not racked, I doubt the older DC300As run any hotter than the later DC300A-IIs I use and I've never had a problem, even in an enclosed cabinet. Crown made electric fans and "chimneys" for the later PS-400 that clipped to the cooling fins. They'd probably work on the 300s without much work but I doubt you'll ever hit the thermal protection. I did, once, with a D150 pushing 030s pretty hard outside.

The 150 was the oldest version, and without the faceplate. I used to keep it on its side, the way it would have sat with a faceplate, but without feet to give it any air underneath. When it went into thermal shut-down I simply stuck a good old #2 pencil underneath it to slightly raise it and it continued the rest of the day with no issues.

[grumpy]

Hey Doc.

I'm w/ Beemer on this. If you have open air around the fins/grates/etc...
in a home environment, these amps are both fairly efficient (say vs. class A)
and will mostly be loafing along. I'm guessing full volume techno is not
on the menu often. :D

My only concern (which isn't much) is if you decide to bridge an amp,
-and- push continuous levels... this can stress an amp a bit more than
when used "normally." ... doesn't sound like this should be a problem
for you though. If heat sinks get hotter than you can leave your hand on
indefinitely (not necessarily comfortably), you've passed ~50degC, which
is a reasonable point to add a fan. Pabst fans, when run at a lower voltage than
spec, are pretty quiet.

[Doc Mark]

Hey, Beemer and Grumpy,

Thanks, Mates! That's what I was hoping to hear. I do have an old amp rack, that I used to use back when I was playing music for a living. It's solid, but an ugly POS, so I'll have to do a little something to make it look a little more presentable in the home. Only the Crowns, the crossover, and maybe my Soundcraftsmen AS1000 (if I decide to drag that out of retirement) will be rack-mounted, with the HK units will be stacked with the CD/DVD player, tape deck, and EQ. If I get rid of my old stereo cabinet, again nothing to write home to Momma about, I'll have to come up with a new cabinet for that stuff, plus the turntable, and TV. Hummmm, could be nice, getting something new.

Grumpy, how was Hawaii??!! Are you rested, tanned, and pina-colada'ed out??!! ;);):D:D Hope you had a good trip, and I'm glad that you returned, safe and sound.

Thanks, again, Guys. Your thoughts are much appreciated! Take care, and God Bless!

Every Good Wish,
Doc

P.S. The way it's looking right now, each 2235H will get it's own Crown amp, probably bridged-mono; each pair of 2123H's will get an H/K 870; each pair of compression drivers/horns (2420/2307/2308, or 2445J/2311/2308, or2445J/2380A)will get an HK/ 870; and the 2405's will get the HK 65 wpc in the AVR20. That should give me more than enough headroom, for most stuff, and I think all those amps will run fairly cool, as Grumpy suggested. For our listening habits, it's probably tons of overkill!! but, I can't help myself!! This could be FUN, Friends!! IF I end up being able to get that 4518 cabinet down from Portland, then one of the Crowns, definitely bridged-mono, will be used for that cabinet, which will be stuffed with that 2242HPL I got a while back. Goodness, that would make it a 5-way system, wouldn't it??!! Oh, Goodness Gracious...... I've been hanging out here too long, I fear!! ; ) I'm going to have to clean up this place, so that I can snap a few photos and post them here. I've been super long-winded, since I joined, and not a photo to my name to back it up!! <LOL!!>

[BMWCCA]

Doc,

Not sure we made it clear that if you're using the Crowns just sitting on a shelf, with the bottom feet present and accounted for, with just normal air-flow around the fins, you'll be fine. The admonition on spacing was just for rack mounting which could limit air flow if you don't leave enough space. None of mine are racked, yet, though I did get an overbuilt six-foot-tall beast free with the bundle of SAE stuff recently. Rock on!

[Doc Mark]

Evening, BMWCCA,

Thanks for the clarification. That's pretty much what I thought. However, none of my Crowns have feet, at all! :o: So, they will, more than likely, be rack-mounted, and I'll be sure to leave some space between them, and the other components, as you have wisely suggested. Thanks, very much! I'm looking forward to all this coming together, and can't wait to get started!! Take care, and God Bless!

Every Good Wish,
Doc

[Mr. Widget]

Its simple really. Cool electronics live longer than hot electronics...


Widget

[BMWCCA]

However, none of my Crowns have feet, at all!Mine either. Those heavy-duty stick-on rubber feat available at your local big-box hardware store work great.

[hjames]

But you can always do what I did - get some of those short rackmount rails at Guitar center, get some attractive wood for side panels (mine were some cut down Beech veneeered scraps from IKEA) and make a mini rack -

Mine holds an Ashley crossover, a JBL/UREI 6230 amp and a JBL/UREI 6260 amp, has some vent panels, and is reasonably attractive.

http://audioheritage.org/vbulletin/attachment.php?attachmentid=31709&stc=1&d=1206142264

[grumpy]

Its simple really. Cool electronics live longer than hot electronics...

yep. just gotta balance cost/noise/use/convenience vs. equipment lifetime.

Worth repeating that It is fairly easy to overheat equipment in a closed space,
especially when designed for open-air placement, or blow-through ventilation.

Nice DIY equipment rack, Heather.

[Doc Mark]

Hey, Heather,

That's a wonderful idea! Well done! I will most certainly give something like this a go, when I'm all set and ready to begin this. Still have to get the Ashly crossover, though. I asked in another thread, but does anyone have a reputable mail order firm, with which they deal, for ording such a critter? And, where do you score those rack vents? Guitar Center?

Thanks, to one and all, for your suggestions. All good, all appreciated! Take care, and God Bless!

Every Good Wish,
Doc

[Fred Sanford]

Hey, Heather,

That's a wonderful idea! Well done! I will most certainly give something like this a go, when I'm all set and ready to begin this. Still have to get the Ashly crossover, though. I asked in another thread, but does anyone have a reputable mail order firm, with which they deal, for ording such a critter? And, where do you score those rack vents? Guitar Center?

Thanks, to one and all, for your suggestions. All good, all appreciated! Take care, and God Bless!

Every Good Wish,
Doc

I've generally used Middle Atlantic for racks (wood-panel sides, too), rails and vented blanks:

http://www.middleatlantic.com/

They can be purchased through Sweetwater and Markertek, I've had good history with both:

http://www.sweetwater.com/

http://www.markertek.com/

je

[macaroonie]

Bear in mind that each amp is only handling a segment of the audio spectrum, esp the ones driving the 077/2405, and as a consequence the gross amount of power is a good bit less than would be the case with one amp running full range and then into a nasty passive crossover. The crux of the matter is that a fully active set up is much more efficient in terms of power hence for a given SPL you will use less. In short your amps will be cruising.
One thing I have noticed though is that with everything so nice and clean its quite easy to drift into really quite high SPL's without realising, that is until you find yourself shouting to be heard.
When you get to rigging up do yourself a favour and get some nice new cabling and connectors ( see the Backyard thread ) and make sure to draw a schematic of your hook up so that you can keep things in order. Maybe even colour code the cables etc.
Have fun oh pics would help. Mac :D

[scott fitlin]

DC-300A,s running bridge 8 ohms for low frequency woofer, will need some fan cooling assistance. I ran 300,s every season from '77 till last year, they get hot. And, at relatively low levels, with a recording that has alot of content at 50hz and below, they will get hotter, faster than almost full output at 100hz and up.

DC-300A,s bridge mono @ 8 ohms for LF should have fan assistance especially if you like to push your system.

I am running 1 DC 300A on mid horns, six 16 ohm drivers, 3 per channel, parallel, nominal 6 ohms per channel gets warm, not hot, never thermals.

300 is for bass or mids? Bass, you need fans!

[Doc Mark]

Hey, Fred, Mac, and Scott,

Thanks, once again, Guys! Great thoughts and suggestions, and all much appreciated!

I'll most certainly check out the links for buying an Ashly, and I hope, fairly soon. I'll probably get a few odd bits of hardware, too, whilst I'm at it.

Mac, photos will, hopefully, soon be forthcoming. I actually snapped a few the other day, but after checking them out, our living room is a pit, since Sweet Bride has been working overseas!! I've got crap strewn from saucer to teacup, and there is more dust then you'd find in a coal bin!! :o::o::(;):blink: And, you can SEE all that in the photos, too! So, taking new photos, and then posting them, will have to wait until I get a little more work done, and can spend a day cleaning up the myriad messes I've created in Sweet Bride's absence!! While the Sweetie's away, Doc has most certainly "played", and that will all have to be cleaned up by next week, when she returns!! Hope to take and post photos, then.

Scott, at the volumes to which we're accustomed, I don't think that the Crowns should have to work too hard, even when running a single subwoofer. Crossed over low enough, that 2242HPL will only be called upon for very low bass, and the rest of the time, it will be in the audio waiting room, or the low frequency batter's circle, waiting for it's time to shine!! ;):D But, all this will either bear itself out, or not, once I actually get to assemble this stuff into a usable system.

Thanks, again, to one and all!! Take care, and God Bless!

Every Good Wish,
Doc

[Fred Sanford]

My links were places to buy Middle Atlantic rack gear, but hey- they sell Ashly too! Who knew?

You're welcome, best of luck with the system. My 4333As are currently bi-amped with an old Ashly x-over.

je

[scott fitlin]

My 4333As are currently bi-amped with an old Ashly x-over.

jeHow old? 12DB slopes. possibly?

[Fred Sanford]

How old? 12DB slopes. possibly?

Ashly SC22, circa 1983:

http://www.ashly.com/retired/spec-sheets/sc-crossovers.pdf

Stereo 2-way crossover, 12dB/octave filters,
crossover frequency range-160Hz--8KHz,
Rolloff = 1.5dB--12dB
Input Z = 10K ohm balanced
Output Z = 50 ohm unbalanced
Max in/out level = +20dB
THD = <0.05%, @+10dBV 20-20KHz
Hum & Noise = -90dBV
Power Consumption = 5W

How's the business? Never saw you respond in the "Say it isn't so" thread...

je

[scott fitlin]

Ashly SC22, circa 1983:

http://www.ashly.com/retired/spec-sheets/sc-crossovers.pdf

Stereo 2-way crossover, 12dB/octave filters,
crossover frequency range-160Hz--8KHz,
Rolloff = 1.5dB--12dB
Input Z = 10K ohm balanced
Output Z = 50 ohm unbalanced
Max in/out level = +20dB
THD = <0.05%, @+10dBV 20-20KHz
Hum & Noise = -90dBV
Power Consumption = 5W

How's the business? Never saw you respond in the "Say it isn't so" thread...

jeOK, I can tell u whats really goin on, but I cant put it in print, PM or Forum, I can PM u my phone #.

[JBL 4645]

If heat starts to worry you then get a few cheap pc fans and place them around the amplifiers that should keep things cool, because heat raises and sometimes I notice the heat coming off the x3 Alesis RA300 I’m roasting.:D
(http://www.yourgreendream.com/images/projects/yp_solar_fan_fan1.JPG)
http://www.interpacbv.com/IMG/Acousti/afdp-12025b.jpg

[Doc Mark]

Greetings, Friends,

Thanks to one and all who offered suggestions and comments on this! Much appreciated!

Back when I played music for a living, I used my first old Crown, a DC300, in an enclosed box, with it's own EQ, to power my vocal monitors. I had built a nice, and very solid wooden box, covered with Tolex, to house it, and that worked very well. However, I soon found that the closed box caused that old Crown to run VERY hot, indeed, and immediately cut a hole in the rear of the box, and installed a Whisper Fan inside it. Ahhhh.... that was much better, and from then on, the Crown ran as cool as a cucumber!

For this current situation, however, the box will be larger, and open in the back, so I will use it first, then decide if a fan, or fans, are necessary. I agree, 100%, that "heat kills", when it comes to electronics, and so will be very careful to monitor the situation, and take steps to add cooling, if needed. Thanks, again, Friends! Being able to seek guidance and wise counsel from you all, is always a pleasure and much appreciated. Take care, and God Bless!

Every Good Wish,
Doc

[JBL 4645]

All electronics generate heat right down to small mobile phone, you only have to place your finger on the LCD display and feel a mild heat coming of it. Even are own bodies generate heat if that makes you feel any better about this.;)

[jcrobso]

If the heat sinks get to hot to touch, get a fan!:D john