WTH -- UL back to triode connection

zigzagflux · 6th February 2007, 01:36 AM

What in the world....

Have a ST70 with kevinkr's driver. Was originally hooked up in triode mode. Had nice looking square waves after some tweaking (under a previous thread). NO problems.

Out of curiosity, I connected things in Ultralinear (only the left channel), just to hear the difference. No big improvement, so I went back to triode.

Now, square waves look like this. Sorry for the blurriness, but you get the picture.

What happened? Doublechecked I put the 100 ohm resistor back - from pins 3 to 4. UL tap is connected to pin 6, which has no internal connection.

????????

SY · 6th February 2007, 02:11 AM

What's the frequency? If that's 100 Hz or less, you're seeing the normal LF rolloff.

zigzagflux · 6th February 2007, 02:42 AM

HAHAHAHA.

No, it's 1kHz, and I had a major brain fart.

Yep, it's LF rolloff.

I have a 80Hz 6dB filter on the input, and forgot to inject after it.

Sorry for wasting your time.

Doggone, you are quick and accurate, SY.

Wavebourn · 6th February 2007, 02:59 AM

I thought you've fried your output tranny.

6th February 2007, 02:11 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	What's the frequency? If that's 100 Hz or less, you're seeing the normal LF rolloff. __________________ If there's a sucker born every minute, where do the rest of them come from?

6th February 2007, 02:59 AM	#4
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	I thought you've fried your output tranny. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

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6th February 2007, 02:42 AM	#3
zigzagflux diyAudio Member Join Date: Oct 2006	HAHAHAHA. No, it's 1kHz, and I had a major brain fart. Yep, it's LF rolloff. I have a 80Hz 6dB filter on the input, and forgot to inject after it. Sorry for wasting your time. Doggone, you are quick and accurate, SY.