telecaster
1000+ Head-Fier
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I tried the elevated heater, the hum is now minimum of the minimum, and should never be a problem anymore for me.Maybe try other ef86?
About the hum in noisy driver, anyone is brave enough to try this mod?
It's about the noise induce in the drivers by the heaters power.
1. Creating a virtual center tap
2.Elevating the reference of the heater voltage
https://www.head-fi.org/threads/darkvoice-336i-336se-tuberolling-partii.348833/post-16182719
I know it is performed on the 336se, but the idea should be the same for the 339.
I for sure will try his diode mods on the 6as7g socket in Order to slow start the filament heating. But it's another mod that the hum noise mode. It's for protection g tubes from arcing.
Super happy!
It is still not still tombstone silent when volume pot is wide open, but it's pretty much as good as can be. Practically hum is now a non issue for the 339. But looking at others testimonies, hum never was a problem for 339 users to begin with!
This mod just reduces it drastically ^^
I advise for the novice to only do the center tap mod, as it is a huge improvement over the stock heater noise.
Here is a photo. Just follow the guide : https://www.head-fi.org/threads/darkvoice-336i-336se-tuberolling-partii.348833/post-16182719
You need to make sure to disconnect the heater from the ground at the driver socket.
And no need to disconnect or change the led at all.
And here is the elevated heater in my amp :
I also wire a diode in the 6080 socket in order to protect the tube from arcing. It's a like a time on the B+ while the heater is heating the filament if I understand correctly.
So on the photo above, the 100K resistor and negative leg of the 10uf green cap is connected on the ground bus. You can see both 100ohm blue little resistors on the heaters, and the big red carbon resistors is the 220K connected to the + lug of the second last power cap.
Just for information the B+ is around 140V at the second last cap and the elevation is 40V
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