SCM50ASLT anniversary and amp pack heat variation.

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SCM50ASLT anniversary and amp pack heat variation.

Postby Lemen » Tue Nov 01, 2016 11:58 pm

Since acquiring my pair of SCM50ASLT anniversary, I've noticed that there is a very large variance in heat output from each speaker's amp-pack.
When touching the heatsink and backplate in various places, the same points are all much hotter on the one speaker than the other. Particularly the left side of the backplate, aprox midway up the heatsink (as viewed from the rear). The one unit is too hot to touch, whereas the same place on the other unit, it's possible to keep finger contact. This is at idle.

It's something I will ask ATC to investigate when the speakers are returned for their tweeter upgrade, but I wondered if anyone had noticed similar?
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby studioman » Wed Nov 02, 2016 3:03 pm

Lemen wrote:Since acquiring my pair of SCM50ASLT anniversary, I've noticed that there is a very large variance in heat output from each speaker's amp-pack.
When touching the heatsink and backplate in various places, the same points are all much hotter on the one speaker than the other. Particularly the left side of the backplate, aprox midway up the heatsink (as viewed from the rear). The one unit is too hot to touch, whereas the same place on the other unit, it's possible to keep finger contact. This is at idle.

It's something I will ask ATC to investigate when the speakers are returned for their tweeter upgrade, but I wondered if anyone had noticed similar?



That sounds like something is not right. Either the hot one is overheating, or maybe the cooler one is not heatsinking properly, (perhaps the heatsink compound needs topping up the heatsink bolts are loose.)

They should be similar.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby MattSPL » Wed Nov 02, 2016 3:54 pm

I used to have a Krell FPB200 power amp. The heat sink on one side became very hot like you describe. The problem was the bias needed recalibrating, so it was an easy fix by an engineer.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby Lemen » Wed Nov 02, 2016 10:31 pm

@MattSPL @studioman

OK then, and as suspected, this will need looking into in more detail.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby MattSPL » Thu Nov 03, 2016 1:24 am

Lemen wrote:@MattSPL @studioman

OK then, and as suspected, this will need looking into in more detail.


Please let us know the outcome.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby studioman » Thu Nov 03, 2016 8:58 am

MattSPL wrote:I used to have a Krell FPB200 power amp. The heat sink on one side became very hot like you describe. The problem was the bias needed recalibrating, so it was an easy fix by an engineer.


I've still got an FPB200 about to become 'surplus to requirements' Anyone need one with passive ATCs or other passive speakers?
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby MattSPL » Thu Nov 03, 2016 9:56 am

studioman wrote:
MattSPL wrote:I used to have a Krell FPB200 power amp. The heat sink on one side became very hot like you describe. The problem was the bias needed recalibrating, so it was an easy fix by an engineer.


I've still got an FPB200 about to become 'surplus to requirements' Anyone need one with passive ATCs or other passive speakers?


Stop teasing :lol:
Seriously good amplifier with seemingly limitless power. I used the FPB200 with PMC IB1's and the bass slam was immense :D It was like being in a nightclub.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby studioman » Thu Nov 03, 2016 8:21 pm

I'm not teasing, it's just an incredible coincidence. I was serious, Matt. I have an FPB200 sitting right next to me....

I am building a rack unit for my SPL preamp (in the foreground under the Kimber Mains Lead, stopping me taking a better pic!) and the Krell is just behind it on the bottom shelf of my cupboard. Picture below.

This is all meaningless to anyone else!!!!

I can't believe that you had one too, and you had PA65s as well as me, didn't you?

My Krell was put to use with my Celef RT1s....

Parallel lives or what? !!!!!

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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby MattSPL » Fri Nov 04, 2016 11:32 am

Hi David,

Yes, I loved that Krell amp. I sold the PMC's and Krell when myself and Clare bought this house. It was a lot of fun that system, but too easy to get carried away with the volume control :D

I had the PA-65's about 4 years ago and had also planned to make them into scm150's, but downsized my system and moved the sitting room around which didn't suit big speakers.

Cheers
Matt
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby darrenyeats » Fri Nov 04, 2016 6:02 pm

I owned an old KSA-100 for a time. Amazing grip, the Krell KAV-300i integrated that replaced it was a mere toy in comparison.

Heck it's Friday! I sometimes dream of getting 3 Krell class As of ascending wattage and calling ATC to sort an external active crossover! Or even better, with 150s - imagine putting an FBP-600 channel into the 15inch SL driver.

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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby studioman » Fri Nov 04, 2016 8:23 pm

darrenyeats wrote:I owned an old KSA-100 for a time. Amazing grip, the Krell KAV-300i integrated that replaced it was a mere toy in comparison.

Heck it's Friday! I sometimes dream of getting 3 Krell class As of ascending wattage and calling ATC to sort an external active crossover! Or even better, with 150s - imagine putting an FBP-600 channel into the 15inch SL driver.


If you are ever serious about wanting an ATC 3-way active crossover, I have an ATC EC23 which I would be willing to sell. :-)
They say if you can remember the 60's, you weren't really there. Now somehow I have reached 62...oh shit, it's 63 now....How and when did THAT happen?....there's a lesson there somewhere if only I could figure it out...

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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby darrenyeats » Sat Nov 05, 2016 12:18 pm

Thanks for the offer. Active 50s are more than enough in my small room. If we move house, it will likely be a down-size too. Only if I got a bigger space would I then go for bigger active ATCs (let alone the rest!)

Regards, D

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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby Lemen » Sat Nov 05, 2016 7:30 pm

MattSPL wrote:Please let us know the outcome.

Will do Matt. It will probably be early into the new year before I get around to the hassle of packing them up to go back to ATC.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby MattSPL » Sat Nov 05, 2016 11:11 pm

darrenyeats wrote:I owned an old KSA-100 for a time. Amazing grip, the Krell KAV-300i integrated that replaced it was a mere toy in comparison.

Heck it's Friday! I sometimes dream of getting 3 Krell class As of ascending wattage and calling ATC to sort an external active crossover! Or even better, with 150s - imagine putting an FBP-600 channel into the 15inch SL driver.


I had a Kav300i and a 300iL at one point. Both nice amps, but your right, the big power amps are a different breed.
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Re: SCM50ASLT anniversary and amp pack heat variation.

Postby samsie » Wed Dec 21, 2016 4:29 pm

Any update on the heat issue?

I own a pair of 50A Anniversary in pro black. I have the same problem. The left one about 5 °C hotter though both of them perform normally.

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