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Hey guys I kept seeing everyone talking about how bad the tubes are that come with the DV so I bought a Tung-Sol 6SN7GTB pre amp tube to replace the rusty scratched 6SN7 tube that it came with. After installing the new tube there has been a loud hum a couple seconds after I turn it on. I read that you can run the amp for numerous hours or days to eliminate the hum. Does anyone know if this is correct or could it be a defective tube? Do I need a new power tube also can I not just replace the pre amp tube?
Generally speaking, you'll get hum or a slight static for about 30 seconds while the tubes warm up. This is normal for tube amps in general. It may decrease as the tubes get some more on time, but that's just the nature of the beast.
I have the same tube and it also produced a hum as this is very common with most replacement driver tubes. You need to turn on your Darkvoice with the power tube removed for up to 72 hours, until the humming subsides. This allows the driver tube to burn in properly, and since the power tube is removed the unit will not generate any heat.
yes thats right.. u have to burn the tung-soul.
- turn off the DV remove the power tube (6AS7) install the tung-soul (6SN7GTB) then turn on the dark voice try for 24 hour if still there is hum try for 48 hour then every thing will be great cheers :)
I burned it in for over 72 hours and the hum is a lot quieter but it is not gone.. The stock tube seems better XD
No burn it more and it will gone 👍🏻 It’s happened with me and i burnt more than 72 hour just keep try 👌🏻
Ill give it another day and let you know how it goes
Ok so I burned it in for 30 more hours and the hum is very quiet. I almost cant hear it! thanks :D
Great news keep burning enjoy👌🏻👍🏻
Forget burning. The reason for the hum is the filament (or heater) is fed with ~7 VAC instead of 6.3 VDC and in some tubes like the Tung-Sol (i also have one) it induces a charge in the cathode, i read somewhere that is like a "diode effect" between the filament and the cathode. The best solution should be use those 6.3 VDC. The easy way is to make a bypass in the cathode resistors with a pair of capacitors in the pre-amp tube. Search for "Fitz Hum Mod" in the Internet. Higher the value less noise but also more bass roll-off, the usual values are 100 to 220 uF. Just make some tests and choose the better for you. I tested from 47 to 470 uF and finally i use 100uF capacitors and the hum is almost gone in the left channel and slightly audible in the right channel when no input, and not audible at all in both channels when playing music. (Apologies for my english).
The hum is completely gone! It took about five 24 hour days to make it go away but there is not a trace of it left. It sounds so good :D
I had hum... I burned it in 12 hours... still hummed... I finally listened to your advice and burned it in 72 hours... MAGIC! Thanks for the great advice.
Did you mean use 6.3 volt tubes or 7 volt tubes?