Upgrading Lesson learned ( I hope [emoji16] )

[andyrlb]

Some months ago I was very happily listening to my Ruark crusader 2’s hooked up to either exposure ( mono 8’s or dual 4 ) or HD audio amplification , I remember thinking damn this sounds so good and then I spotted a beautiful pair of Mowgan Mabon speakers which were in a beautiful santos rosewood finish, off I went to Essex to view them , after demoing them I was sold and I would collect them the following week, well that all went tits up as the seller just kept messing me about saying he had personal problems and one excuse after another ( I should have known when his wife was just rude at the demo )
He was clearly just another t%^t .
Now the seed had been planted and I was obsessively ( my autism ) looking for a better pair of speakers and then I stumbled across Oli’s ( bigman ) Ekta 2’s but they were way out of my price range! Then the Autism kicked in and the brain went into overdrive ( I had to have them ! ) .
A week later and with a killer migraine I was driving home with them , had to stop around 6 times to vomit and sleep, got home and collapsed into my bed .
Next morning I’m as bright as a spark and I eagerly hooked up the speakers and …… a cloud of disappointment came over me ( I’d sold the Ruarks btw ) I thought what have I done! I then contacted Oli and he just couldn’t understand why I was so disappointed
until he asked what amplifier I was using ( I told him) then he knew there lay the problem, not enough power for the speakers THEY NEED POWER he explained , he was so right.
So I now have the most expensive purchase I’ve ever made on hifi and I can’t enjoy them ( gutted ) so I’m now skint but hey I can look at them right
But this was like having an R8 only firing on half its cylinders , I had to hear these beauties as they’re meant to be heard and then the next journey began .
I sold off some more hifi bits and then began scouring the for sale threads and there it was THE BEAST that would drive the Ekta 2’s .
It was a non working Threshold Stasis 2 ( 200w class A ) once again I obsessively researched the amp and decided to buy it ( or exchange some hifi for it )
The seller even agreed to bring it to me ( yes the alarm bells rang ) I ignored the alarm bells as something told me that this is what I must have for the speakers to sing at their best .
Got the amp home and started investigating , burnt boards ! Burnt out traces !


But that wasn’t enough to stop me resurrecting this beast ( I mean how difficult can it be ? )
HOW DIFFICULT ? Absolutely incredibly difficult was the answer
The boards are totally toast and irreplaceable!
It was then I reached out to some wonderful people on DIY audio and only with their help and guidance I could set about restoring the beast .
I think it’s one of the most testing of projects I’ve ever undertaken ( even with their help )
I was told that it’s a very very complicated amp to work for some of them let alone a complete novice such as myself.
But with persistence, all new FE boards , new power supply capacitors, around 24 On Semi output transistors, all new wiring etc etc it was ready for testing ( 2 months down the line )
Now was the time that those clever guys on DIY would learn more about the stasis 2 as it hadn’t been done before as far as we knew ( no threads about it anywhere)
I had to establish the voltage at the voltage rails and loads of different things before powering on ( I bought a variac for this )
Variable pots were set to maximum resistance and the beast was ready for power on ( I was crapping it ! )
POWER ON and all is well ( house lights dimmed momentarily)

Then I had to connect my 4 multimeters in order to bring it to life , I did so and slowly I was to lower the resistance at the pots until it got to a certain mv at a 1Ohm resistor and then in turn the temperature would rise and eventually the amp would become stable .
More problems discovered at this point, we then learned that a certain number of the output transistors were fake ! Fake Motorola’s in fact , so more On Semi transistors ordered ( now all 48 are genuine On Semi )
We also learned from one of Nelson Pass’s mates that the amp MUST be all bolted together in order to set the bias , so I bolted it all together soldered everything and powered it on again ( without the variac )
Now we’re getting somewhere, bias was raised 85mv at the emitter resistor ( over a matter of hours ) but the temperature is too low ( 39c ) it needs to be at 45c minimum so more fiddling with the pots to get to temperature then finally ( after many attempts) it’s stable and the bias is set .
It’s at this point that I learned that there’s no speaker protection in the amp so if it goes pop then the speakers will go bang !
After leaving it powered on for a few days I plugged in some cheap speakers and WOW ! Music was actually heard from something that I had restored.
A few days later I had to try the Ekta 2’s after all they were the cause of this long and at times stressful journey.
Bloody hell Oli was totally right! Now with this 200w class A beast up them they were/are sounding better than any speakers I’ve ever heard ( PERIOD ) .
As I write this it’s a week later and the amp just gets better and better and the speakers are just stunning in every way.

The morel of the story is “ be careful about matching when upgrading “
Am I as happy now as I was those few months ago YES , was it worth the stress YES , I really don’t think I could better the speakers or the power amp without a shed load of money.





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