TSSA V1.6 docs and buyers list

[Siberia]

Sorry for being doubting Tomas, but I'm afraid to burn it. Moreover my speakers.

Everything is set and ready for listening. Just powered up to monitor bias for the last time and it showed just a bit more than 50 mV from the start decreasing gradualy. I didn't wait for it to climb down. Switched off. Last time I left it at 30mV after 10 min on. Is it normal, doctor?

 

[buzzforb]

It is expected if you set final offset and bias after letting it warm up. Transistor bias will change with increasing temperature. Turn it on and watch it, I would expect it to come down as it heats up. Sounds like all is fine to me.

 

[Siberia]

Just measured the other channel. It's the same. Starts at 54 mV decreasing to 48 mV after half a minute. Didnt wait longer.

The only difference now from the last power up is that the amp is assembled into the box more. Got a front cover, the bottom is mounted to the heatsinks. The rca sockets are hooked up too. But I don't think that could influence the bias.

 

[Siberia]

Alright, I'll power it and watch it drift.

 

[sonnya]

Yes it is normal that the bias current peaks shortly after power up.

There is two bias generator. They are not tracking 100% thermally and that is the reason for the peak.

It will not burn or destroy any thing. But after 10 min as you says, it is stabilized.

It is something i am working on in revision 1.7. An i will make upgrades kits, but sound wise it has no effect.

It is a trade off to get rid of cross over distortion when clipping.

 

[buzzforb]

Sonny, what other, if any revisions are planned?

 

[sonnya]

I need to make a blind test on the bypass caps if it need to be there or not.

Secondly it Can be enhanced to ~ +/-45v supply voltage.

 

[Siberia]

After five minutes it's at -39 mV when measured across R30 facing the readings. Black probe at the left, red at the right side.

 

[Siberia]

At 37 mV after 10 min. Still decraesing but very slowly. Looked like stable for some time. Should I rebias?

 

[sonnya]

No, would let it be. You Can readjust to 50mV. But it is a slow process.

 

[Siberia]

I checked up both chanels. There's 3 mV difference. 36 and 33 more or less stable maybe drifting 0.2 mV

 

[sonnya]

Let it be. It is difficult to get much closer.

 

[buzzforb]

If exicon have negative tempco( I believe they do) adjust 5mV higher than you want and it will fall as it heats up. To be irritating, you are also watching offset at speaker terminals, correct.

 

[Siberia]

35.4 mV and 32 mV. Offset 5 mV and 2 mV. Shut down and power up for listening? Or should I measure offset at power up first?

 

[Siberia]

First measurement at R30, second at speaker terminals (offset)

 

[buzzforb]

Power up will always show levels that are slightly off. Listen to it. You have earned it. I have turned on amp that had 300mV offset at turn on. Your speakers will be fine

 

[Siberia]

Alright, one last thing. At one chanel voltages are the same on both power resistors, but on one temp is 10C higher approaching 70C

 

[sonnya]

The amps drifts very little In the output offset voltage.

But p+/-50mV offset is okay on This AMP.

 

[sonnya]

You have to believe me now. It is fine.

 

[Siberia]

I believe you, Sonny. Powered up one channel. There was quite a noise coming from the speaker with the pre vol. at 0. Hard to describe the noise and sorry for being such a mess.