HT40 Volume drop

Discussion - HT Venue amplifiers. Inspiration from Studio to Stage.
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DreamTheater
Posts: 20
Joined: Thu Dec 03, 2015 11:08 pm

Mon Jan 04, 2016 5:54 pm

I've got a new (Red)HT40 That has Ruby preamp and power tubes. I had a strange drop in volume while playing. Also it seemed like the distortion level also was reduced during the episode. My TC Electronics G Major was connected thru the effects loop at all times. I have removed the processor completely and now cannot seem to replicate the volume fluctuation? The tubes glow a gentle orange, no bright red or purple. Anyone have experience with this condition please chime in. Thanks

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thephantum
Posts: 1160
Joined: Wed Jan 29, 2014 7:42 pm
Location: Virginia, United States

Mon Jan 04, 2016 7:44 pm

Drops in volume and/or OD levels are usually signs of a failing output tube. If I had to guess: when the G Major was in the loop, it was boosting the signal a little and pushing the output stage a little harder than just the preamp would....which exposed a bad power tube. That would explain why you can't reproduce it without the processor in the loop (It's possible that the G-Major has a problem, but I doubt it).

The only thing looking at the tubes will tell you is a) if they have power and b) if they are red plating or not. There are literally dozens of failure modes where the tubes will be happy glowing and appear normal.

DreamTheater
Posts: 20
Joined: Thu Dec 03, 2015 11:08 pm

Sun Jan 31, 2016 3:17 pm

I swapped out the two stock Ruby preamp tubes for an old pair of Electro Harmonix tubes that I had laying around and although I dont care much for the change in tone that the EH tubes offer, they seem to have eliminated the volume fluctuations and scratchy anomalies the were present with the stock Ruby tubes. It may have been one or both of those tubes that were bad.

DreamTheater
Posts: 20
Joined: Thu Dec 03, 2015 11:08 pm

Mon Feb 01, 2016 6:26 pm

Thanks Phantum for the information you provided me. After fiddling with tube swapping and G Major input / output levels I thought I had my problem solved but it continued to randomly reoccurr. Last night I discovered a faulty speaker cable (stock ). I replaced it with a known working cable and seems to have solved my problem.

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