2. amps-preamps
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Problem with Ref 5SE

I recently purchased a 5se and took delivery the other day. Did not get a chance to open it up until last night. Upon installing it into system I switched it on and after it warmed up, I was very much interested in hearing how it sounded against my current 27. After listening to several tracks with the 27 I switched pre's and after a couple of minutes playing a CD I got some noise, almost a loud static sound coming from the right channel. It was not effected by changing volume controls or input selector. It went away after 10-15 seconds and then returned. At that point, as it was late, I shut everything down and figured I would take another look in the morning.

This morning I removed the top cover and pulled and reset the output tubes and then the power tubes. I fired it back up and still had the 'static' sound but now it also had a humm, like an impedance type hum and constant. I do not believe that the humm was present last night as it is quite noticeable. 

The static type load noise seemed to have abated after the unit warmed up after maybe 15-30 minutes.

Can I assume that perhaps a tube was damaged during shipping? Do you ARC guys think a new set of tubes will fix this issue or am I looking at something more severe? Any additional suggestions to try and pin this down?

I rerouted the IC going to the amps to get them further away from source IC's and no help...

I am a little bummed, as my initial impression it that it is a leap from the LS27, my current...
128x128stevea11757
larryi
3,973 posts
 
I would expect the plastic top to retain heat inside of the component more than would the metal top.  The metal top should do a better job of radiating heat into the air. 
motorheadflash
10 posts
 
Would you care to jump in on this Trackman. You think the plastic top would be cooler. I'm not shure,  Anybody else got a theory?
testpilot
928 posts
 
You think the plastic top would be cooler. I'm not shure, Anybody else got a theory?
An aluminum top will cool will dissipate the internal heat MUCH better than a plastic top.  All you need to do is look up the thermal conductivity coefficient of the material use.  Plastic acts more like an insulator whereas metal will act more like a heat sink.  If you want to increase the cooling capability of an item, build it out of copper
chip_2950
12 posts
 
So...  Just an observation.  
All of my ARC amplifiers over the years have had metal tops.  My VT200 had 8 matched-pairs of 6550’s.  And, a small pile of 6922’s, as well.  It made a great space heater in the winter.  ;-)
stevea11757's avatar
stevea11757 OP
130 posts
 
Update, sort of.... I just installed a PSA P20 that I had ordered before the pre, was kina hoping it was a ground loop issue, but apparently not as noise is still there. The loud static pop sound is no longer evident so I guess resetting tubes helped there. As these are original tubes with just over 1000 hours, to start I will just replace the 6550 and see what happens. Once I increases playback volume to drown out the background noise it really does sound very good a leap over the 27.  

Motorheadflash, that you for describing your issue, sounds pretty much identical. Seriously considering leaving the top unscrewed and removing it when I am doing some extended listening. The pre is on the top shelf of a stand that I made, so ventilation should not be an issue. All the components are sitting on vibration isolators which are sitting on a 1/2" block (so the rubber isolations do not mark the finish on the wood) so there is plenty of free air movement.
 
Tubes will be delivered tomorrow so tomorrow night will be the test. I will be letting everyone know if this was the problem....is it is I guess I should keep a spare handy..


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