Originally Posted by CHRIS650
my fan doesn't have squealing nosie... it sounds like refridgerator's humming...
My 745 doens't have any sound.
If it is a rumbling type sound than it is the larger fan for the amplifier tunnel..
This is triggered by (2) sources, DSP volume level gain and temperature heat sensors mounted on the tunnel...
At certain times this runs @ low speed and sounds like yours may be cogging
as it is trying to start to turn..
Though HK needs to respond, my thinking is either the fan is not mounted and torqued down properly to the tunnel. Or just the fan itself is noisy and to fix this may need to be replaced, or perhaps a slight shot of light oil may help. The fan itself was available with a ball bearing retainer and/or a thrust retainer, the thrust retainer is cheaper but I really don't know whats in your 7550HD.
As I posted previously...
After the 7550HD/760/660 were approved for MP start the original design team was terminated and everything shifted to China. And I have seen & heard that certain OE components were revised
for less expensive
ones to save $...
30 internet radio presets..
Good to know but 10 is enough for me..
But again as I posted previously HK manuals, brochures and website have multiple
typos so I don't really trust any of their published specs...
For example, 1 brochure mentioned the 7550HD power as 75W x 7, another place said 85W x 7 and another 110W x 7.. Whatever its power output really is, drives my loudspeaker loudly & kleenly..
If you have more 7550HD questions just keep pushing HK for their response as hopefully someone can answer the technical questions..
Better than me.. As you know I have spent many hours on this forum helping HK users but frankly speaking this burden should really be on HK to support.. Or maybe I should send them an invoice for services rendered..
Just my $0.02..