Trem Noise

[clyde1]

Hi all. I just completed a Komet clone and put in bias trem, a la 6G16. The trem works very nicely but has a dirty, distorted sound around the note as it's fading out. This is at higher volumes when the amp itself is distorting so I'm wondering if this is unavoidable or not. The B+ to the tube is 400v, perhaps too high? Grounding to the bias ground makes no difference either. Thanks.

[Twist]

Are you saying the note distorts as the trem runs through its cycle? That circuit oscillates the bias which in turn can cause distortion as the bias voltage oscillates.

[Chuck H]

+1
The circuit of the trem tube itself imparts nothing on the signal path besides a variation in bias. So there is no "tone" to the trem circuit. Only how it affects the bias. If the trem circuit presents a poor voltage fluctuation that might cause unwanted distortions. But be clear that no signal is running through the trem circuit.

[clyde1]

It seems to be the clipping of the note itself that sounds rather ragged as it fades. I'm thinking that a lot of distortion and bias trem are not happy campers, esp. when in a circuit where "power tube distortion" is supposed to be the design goal. At lower volumes it's not an issue.

[Chuck H]

Right. Power tubes can't clip predictably with the bias wagging up and down. You might be able to change the bias of the tubes (a little hotter probably) and reduce the intensity of the effect to get something useful.

[clyde1]

Thanks Chuck, I actually increased the intensity of the trem with bigger caps and like the sound better, probably a quicker transition time. I haven't messed with the bias yet, next on my list.