Every new tube is noisy, am I unlucky or am I missing something?

[Mossshine]

Hello,
I have Darkvoice 336 SE tube amp connected to DT 1990 PRO and that I use all the time and I wanted to try some different tubes than my old trusty Sylvania 6SN7 GTB E6B ones so I bought one KenRad 6SN7GT (pricey little thing) and two PSVANE UK-6SN7 (ordered one but arrived as pair)

KenRad is supposedly to be old-new stock and The PSVANE are brand new.

Both of them are noisy, a lot.

• The KenRad noise is in the right channel and is sounds exactly as when you would touch microphone jack connected to a big speaker
• Both The PSVANE have the same issue as KenRad but they are not that loud and after settling in for about a hour both channels have this issue

I am no audio expert, so I went to ask uncle google and found some topics that say that I have to "burn in" my new tubes which I tried but nothing came out of it (took out the power(?, the further one) tube and run the noisy KenRad straight for little over 2 days). Noise does not go away if I change outlets or unplug DAC that's feeding in the sound. I have no other headphones to try, so I can't say changing them would help or not.

The original tube that came with Darkvoice and Sylvania tubes are fine, without any noise. I know that tubes are wonky and the every one is different, but I don't think this is how it should be. I have also considered making the "shunt mod" which should apparently fix some noisy tubes but I am little scared that I would f**k it up, but if someone can guide me I would appreciate it.

Shower me with you wisdom please

 

[abdo123]

How much noise are we talking about? Because most tube implementations are noisy compared to most solid state implementations.

 

[Mossshine]

How much noise are we talking about? Because most tube implementations are noisy compared to most solid state implementations.

Audible even when somewhat loud music is playing. It really is quite loud. Changing the amp volume with the knob does nothing too.

 

[abdo123]

Is it low in frequency (hum) or high in frequency (hiss)?

 

[Mossshine]

Is it low in frequency (hum) or high in frequency (hiss)?

Low frequency. Just like speaker when you touch the 3.5 jack.

Here in attachment you can hear it. I amped it a bit because it was recorded via phone from my headphones, but it does indeed is really loud.

 

[SIY]

I don't know what a "shunt mod" is, but I do know what a poor design with bad grounding does, and it sounds like (no pun intended!) that's what you're dealing with. Chasing tubes won't do it (especially from unethical suppliers like PSVane), you'll likely have to enlist the help of someone who knows what he's doing to modify the actual amp and its power supplies.

Without having it in front of me (or a schematic), I can't know for sure what the specific issues are, but I'll sneak a guess based on a lot of similar sorts of "designs" I've seen, that they screwed up the heater circuit, which could range from abusing the maximum heater-to-cathode voltage (very common) to bad grounding. Different heater-to-cathode leakage from tube to tube would cause the noise to be different when they're changed.

Either way, the amp is the problem, not the tubes.

 

[Jim Shaw]

In the bad old days, when we had nothing else besides tubes, I found that this sort of noise (that couldn't be fixed by tube-swapping) was likely caused by some passive component(s) in the bias, feedback, and/or filtering functions surrounding the problem tube. Resistors are often the cause but caps can also do it. So changing tubes won't cure the issue. Worse, it's a trial-and-error kind of thing to find the bad component.

FOR EXAMPLE: I once worked with a mixing board that had 16 similar preamps - each on a separate chassis, each with two 12AX7s, with a common power supply. Apparently, the manufacturer got a bad batch of resistors, one in each of the similar high gain first stage tube plate (high voltage) circuits. We first identified the stage causing the trouble, then changed all the components in one preamp -- one by one -- to identify the problem resistor. I replaced all of the similar components, in each of the preamps, and voila! The noise was vastly reduced to acceptable levels. (In those days, -55 dB was pretty splendid.)

It's not only tubes that can be noisy. Just another reason that I hope to never own another vacuum tube device (unless it is my microwave oven). I don't need "fat" sounding music that bad.

 

[charleski]

The tubes look fine (no leakage spots on the getter at least). I agree with the other replies: it looks like something's broken inside the amp, possibly a poorly-secured resistor mounted to the tube socket that broke away when you changed the tubes.

 

[MetalDaze]

Hello,
I have Darkvoice 336 SE tube amp connected to DT 1990 PRO and that I use all the time and I wanted to try some different tubes than my old trusty Sylvania 6SN7 GTB E6B ones so I bought one KenRad 6SN7GT (pricey little thing) and two PSVANE UK-6SN7 (ordered one but arrived as pair)

KenRad is supposedly to be old-new stock and The PSVANE are brand new.

Both of them are noisy, a lot.

• The KenRad noise is in the right channel and is sounds exactly as when you would touch microphone jack connected to a big speaker
• Both The PSVANE have the same issue as KenRad but they are not that loud and after settling in for about a hour both channels have this issue

I am no audio expert, so I went to ask uncle google and found some topics that say that I have to "burn in" my new tubes which I tried but nothing came out of it (took out the power(?, the further one) tube and run the noisy KenRad straight for little over 2 days). Noise does not go away if I change outlets or unplug DAC that's feeding in the sound. I have no other headphones to try, so I can't say changing them would help or not.

The original tube that came with Darkvoice and Sylvania tubes are fine, without any noise. I know that tubes are wonky and the every one is different, but I don't think this is how it should be. I have also considered making the "shunt mod" which should apparently fix some noisy tubes but I am little scared that I would f**k it up, but if someone can guide me I would appreciate it.

Shower me with you wisdom please

Hello,

There is always the possibility of your Darkvoice having internal issues. The wiring photos I have seen of the interior leave something to be desired.

I have the same tube amp, and similar to you, bought Kenrad VT231 (Black flashing tube from WWII). Highly regarded. My Kenrad tube also hums very loudly in one channel. I think the left. Tried the same "fix", which was to remove the power tube and leave the pre amp tube on to burn in for 48 hours. Supposedly this may help restore the tube. I also tried cleaning the pins with deox-IT. Nothing worked. That specific tube still hums and buzzes when I try to use it.

Same as yourself my Sylvania tubes which came with it were dead quiet, albeit not the best sounding.

I use Beyer Dynamic DT-880's @ 600ohm with the amp.

I continued trying a few different tubes and my best combination (if you can find them) has been a Tung Sol 7236 for the power tube, and a JAN Tung Sol 6sn7GTA brown base for the pre amp. Completely quiet with the volume 100%. No hums, background noise or pops. I have a decent amount of tubes, and while certain combos may be more appealing for different kinds of music, the Kenrad tube was the only one to cause me issue. Since your stock tubes don't make noise, I'm leaning towards the possibility you are experiencing a similar thing as me.

I only use the amp from time to time for fun, but it should be ready to go when you want to use it. Keep trying some different tubes, if NOS make sure they come from a seller whom has a properly working tube tester, and hopefully is willing to take returns. Some sellers are better than others.

Best of luck!

 

[Mossshine]

Hello,

There is always the possibility of your Darkvoice having internal issues. The wiring photos I have seen of the interior leave something to be desired.

I have the same tube amp, and similar to you, bought Kenrad VT231 (Black flashing tube from WWII). Highly regarded. My Kenrad tube also hums very loudly in one channel. I think the left. Tried the same "fix", which was to remove the power tube and leave the pre amp tube on to burn in for 48 hours. Supposedly this may help restore the tube. I also tried cleaning the pins with deox-IT. Nothing worked. That specific tube still hums and buzzes when I try to use it.

Same as yourself my Sylvania tubes which came with it were dead quiet, albeit not the best sounding.

I use Beyer Dynamic DT-880's @ 600ohm with the amp.

I continued trying a few different tubes and my best combination (if you can find them) has been a Tung Sol 7236 for the power tube, and a JAN Tung Sol 6sn7GTA brown base for the pre amp. Completely quiet with the volume 100%. No hums, background noise or pops. I have a decent amount of tubes, and while certain combos may be more appealing for different kinds of music, the Kenrad tube was the only one to cause me issue. Since your stock tubes don't make noise, I'm leaning towards the possibility you are experiencing a similar thing as me.

I only use the amp from time to time for fun, but it should be ready to go when you want to use it. Keep trying some different tubes, if NOS make sure they come from a seller whom has a properly working tube tester, and hopefully is willing to take returns. Some sellers are better than others.

Best of luck!

That does sound like my issue. Thanks for the tip. I will look for the Tung Sol tubes to try my luck, probably for the last time

 

[MetalDaze]

No problem!

And for sure, no reason to keep chasing your tail if the issue persists. That takes all the fun out of it. And fun is the goal!

For a more affordable / potentially reliable place to look, you can try TubeDepot (no affiliation). Hopefully that will take some of the guess work out of it and leave the amp the only variable.