Threshold Stasis 2.

[docjoe]

one more shot

[Nelson Pass]

I notice that the amplifier has been modified at one time
or another.

[docjoe]

Hi, Nelson!

I bought this amp about 20years ago, second hand and I have no idea on what was done before...
I noticed some discrepencies with the plans I found on Diyaudio but the amp was fine sounding for all these years, until it showed some oscillation problems...

As for visible modifications, i had to put some new binding posts at the speakers and ground solder lugs, as too much soldering had burned the tracks...
added some local decoupling caps on the power boards, you can see and some caps on the underneath of the pcb.
of cource main caps were changed to 22.000/100v BC with bypass polypropylene...
the VBE transistor in now under the PCB
some bleeders resistors to discharge the reservoir caps in the test process but will be removed when the amps are OK

but otherwise the circuit was not changed!

Well it's been a while since I had these oscillation problems,

BTW I' looking for a couple of replacement PCB, because, you know, desoldering and soldering dont leave the tracks undamaged...

best regards

[steenoe]

Thanks a lot for all the information, docjoe I will read through the threads you listed, and try to follow your advice. I did find out one thing though. The peak meter lighting up on one channel, is a fault in the display circuit itself. There is a switch on the rear that can turn the leds on/off. Even in the off pos. they keep lighting in left channel and turns off nicely in the right channel. Somebody obviously got tired of looking at the lights, once. So he mounted a switch. It was not the current owner.

Anyway, here are a few pics.

Steen

[steenoe]

[docjoe]

HI,
I do not have this switch on my amp!

can you put me a diagram of the switch wiring assembly?

have ou a dc offset on the faulty side? and how much?

[steenoe]

Hi doc. The switch is not on the original amp. The guy who made it, took the two peak-sensing leads on the outputs and soldered them to the switch and soldered two other leads from the switch to the outputs. In that way it is possible to break the signal that goes to the front peak display. I can post a close-up picture tomorrow. I just assembled the amp so I could take a good listening to it on my own system tomorrow.

Steen.

[steenoe]

I have been busy Just took a good listening session with this amp. It is louder on the left channel for sure. Also the right channel gets hotter on the heatsink, so I recon its the oscillation thing, allright. It measures like 10 deg. C more than the left cannel. As for DC offset, it is not a lot; left channel is 0,020v right channel 0,034v's. So the bad channel has more offset, no surprise. Otherwise the listening session was fabulous Except for the lower output of the right channel, it sounds really good I could drive my ProAc clones to high volumes, with really good control. The offset is measured with music playing, right at the speaker binding post's.
As a sidenote, I have to mention this odd thing; On the rearplate the right side says left, looking aft from the front and the left channel says right I think someone screwed up If the silkscreen is correct, you have to cross the speaker cables

Steen

[jacco vermeulen]

Unless the owner is cross-eyed !
Even today those Threshold boards look awesome.

[steenoe]

Unless the owner is cross-eyed !

Hi Jaccoboy! You are right, it is really an amplifier!! If it was my own, I would propably restore it Now, I dont think I will use all those ours, to replace everything, like the doc did I dont know, maybe this winter, if I need something to work on
A Threshold Stasis isn't just any amp Still, the damping factor must be brilliant, as it really controls the speakers

Steen