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Had just turned on my Synthesis Ensemble integrated (about 10 years old). while it was warming up, i heard an unusual crackling sound in left channel. Saw at least one tube in left side substantially more lit up - quickly powered off amp. i assumed that stock tubes had finally gone, so took opportunity to order expensive NOS el-84s (8 of them!) that i'd had my eyes on for a while. swapped them in, listened to one song - sounded fantastic. left room for a couple hours, when i came back, crackling was back, and two left-most tubes were aglow.
Thoughts?
Follow Ups:
Get a dental tool or strong jewelers screwdrivers and coax the tube sockets back into their original round shape, or as close to it as you can. Be patient and persistent. Finish with deoxit on sockets and pins - squirt, wait a few seconds, then squirt again. Pay special attention to the grid connections.
Removing sockets requires enormous patience if the sockets are soldered onto PCBs. There is always that last bit of solder that doesn't want to come off, and the tight fit makes it harder to do. I did it once and will never do it again.
It's always a good idea to check the cathode resistors after any failure. Some manufacturers use them as backup fuses of a sort.
You can also get tiny wire brushes to help clean the output tube sockets as well. I think jbtools.com has them.
WW
"They were running on fumes, dazed and confused, in a high-powered automobile."
'You can also get tiny wire brushes to help clean the output tube sockets'
a piece of wound guitar string works pretty good too
the poor man's round file
To err is human, to learn, divine
mans, not 'man is' ..
To err is human, to learn, divine
Here's a thought: DO NOT leave the room for a couple of hours and leave it on! You want to do that kind of thing, get some solid state stuff. Otherwise, be smart and turn it off when you leave for any extended time.
wow that's helpful, thanks.
Helpful for keeping it from happening again!
How much are you willing to get into diagnosing the problem? Someone mentioned tube sockets, with amp on, you can wriggle the tubes see if wriggling one tube causes the crackling. If so, could be loose socket, cracked resistor, bad connection...
Next thing you can do is take the bottom cover off and inspect. Something like 20% of problems are visible. Look for cracked resistors, burnt components, you can poke around with something non conductive see if you can get crackling to appear.
Nest step is get yourself a voltmeter, you can check grid voltages, cathode voltages, plate current etc. One thing nice about stereo, if it isn't a power supply problem you can compare voltages one channel to another. If you decide to get this far into it, post what you see, someone will help you.
thanks. am not particularly handy around electronics alas (recognizing the irony). anyway, given age of amp, am inclined to have a pro fix this issue and do a complete once over of everything- would love to get another 10 years out of it.
As mentioned, maybe loose sockets. Replace them.
Also you may have a bad coupling cap. Those two tubes are in parallel with each other.
Since you put in NOS tubes you may have a couple of duds in there.
You also might want to check the cathode bypass cap. There is only one for the four tubes, but if two are close to the edge, they may red plate while the others don't.
Your amp may be older than 10 years. I believe production ceased in 2008, and the design goes back to 1998.
There is a lot of heat generated inside that little chassis. It could also be bad solder connections.
It may be time to have that amp professionally serviced.
Dan Santoni
thanks Dan. Checked my receipt and it's actually not quite 9 years (and it was a custom color order). Think you're right about need for pro service. Have gotten so much pleasure out of this little amp. I also had the plinth to my Garrard 401 custom built to match the color of the Ensemble, so I'm all in.
Try cleaning the tube sockets. Then re-tension them if doable.
thanks!
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