A Hiccup at the Church of Music in Nature…

IMG_8110a-50pct20x-cWe had a technical problem at the Church of Music in Nature recently.  The church has a pair of Bose® 151 SE environmental speakers on the tall corner posts of the deck, and a line-out feed from the house stereo mounted in the corner of the deck by the sliding patio door, so with the addition of an integrated audio amplifier between the two we get whatever music is playing on the house stereo reproduced on the deck as well.  A summer delight.  For amplification, I initially used the first receiver I ever bought, a delightful little Realistic STA-7, purchased back in the mid 60s.  That served us well for a number of years but died in a literal puff of white smoke two summers ago.  After an almost-futile search for an appropriate replacement, I finally found a Pyle PCA3 Integrated Amplifier; a simple amp in a nice small chassis – one line input, one set of speaker outputs, 75 total watts per channel (more like 20 watts at tolerable listening levels), volume and tone controls, and an on/off switch. A perfect replacement.

This configuration has served us well for a little over two years at the TreeHouse, but a few weeks ago I started hearing some serious harmonic distortion out on the deck when the PCA3 was operating.  It wouldn’t start immediately, but would gradually build up over ten or so minutes, and the amp chassis would get unusually hot to the touch for only low to moderate volume music.  If I shut the amp off and let it cool down, it would sound fine when fired back up – for about ten minutes.  Clearly something was fatiguing under thermal stress inside the amp.  I’m handy with a soldering iron, know how to follow electronic schematics, and even built my share of Dynaco kits in my youth (two Stereo-120’s – one of which I still use, a PAS-3X, and a PAT-4), but the schematic for the PCA3 was not available, and I didn’t pay much for it (~$35 on Woot!), so I decided to replace it rather than attempt a repair.

I checked the usual online suspects (Crutchfield, BestBuy, etc.) but the only things they offered for an “integrated stereo amplifier” keyword search were the big component items with multiple switchable source inputs, AM/FM/Satellite tuners, and HEFT!  Not what I wanted to carry out to the deck on a regular basis, and then back in when done, and find a handy (e.g., close to the deck) place to store it when not in use.  I checked B&H Photo and Pro Audio too – they even carried the Pyle line of amps, including the PCA3 – but I was a bit gun-shy of Pyle amps based on my recent experience, and aside from the Pyle amps all their “integrated amps” were behemoths like what I found at Crutchfield and other places.

On a lark I checked Amazon.com, using the same “integrated stereo amplifier” keyword search, and one item caught my eye – an Emotiva Mini-x a-100 Stereo Flex Amplifier.  A bit more than I was wanting to spend, but it had all the buzzwords in the description that I was looking for; mini, integrated amp, cooling fan, etc.  I had received an Amazon gift certificate for Father’s Day, and with that the out-of-pocket price was more reasonable, so I ordered it.

It arrived last Friday.  I unpacked it.  It was HUGE!  It was as big as – and weighed as much as – the Dynaco Stereo-120 I was using with my PAT-4 as a temporary deck amp replacement.  And it was NOT an integrated amplifier; it had no tone controls, only a volume control.  And oh by-the-way, it was D.O.A. out of the box.   GRRRRRRrrr!

It was packed back up and returned to Amazon.com the next day.  To Amazon’s credit they took it back no-questions-asked, and return shipping was pre-paid (that might have been due to my Amazon Prime membership).

Saturday morning (after hauling out and hooking up the Stereo-120 and PAT-4) I got to thinking about buying another Pyle PCA3, or maybe upgrading to a PCA4 (a bit more power).  B&H had the PCA4 for $50.  Then I got the idea to pop open the PCA3 chassis and at least take a look at the inside to see if I could spot the offending component visually.  Eight screws later I had the cover off and saw a problem immediately… all the air vents in the chassis had been covered by a fairly airflow-restrictive gauze, presumably to hide the “ugly” components from sight when looking through the vents.  I ripped out all the gauze, removed a superfluous bottom plate that also restricted airflow right below the power transistor mounted on a heat sink that was most likely the source of my problem.  And for good measure, while inside I saw that the wires that ran the exceedingly annoying bright blue pulsing power indicator lights on the front panel (so annoying that I covered them up with black tape almost immediately) were connected by a multi-wire plug to the main circuit board, so I disconnected that easily.

I disconnected the Stereo-120 and PAT-4, plugged the PCA3 in and fired it up.  It ran (without the annoying blue power lights). Ten minutes; twenty minutes, an hour.  No distortion, and the chassis was cool to the touch.  I left it on all day, probably nine or ten hours continuously.  Music was clear, no distortion, and the chassis stayed cool the entire time.  Problem solved… I think!

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