[HiFiHawaii808]

If it is 120Hz buzz, most likely leftover unfiltered ripple from the power supply, but could also be rectifier pulses being coupled into the signal path. In either case, that will be design and layout dependent, so not easily fixed. 6SL7 > 6B4G is a lot of gain for a headphone amp using something like a 3K:300ohm output transformer, I'd imagine with a typical 2Vrms DAC input (aka no preamp), the volume control is very sensitive on the 300ohm tap. The noise floor is going to be high on the 300ohm tap given the high gain in this amplifier. I think you can play with setting the preamp output and adjusting the amplifier volume control as you already are, or use the 100ohm tap, but not likely there will be a way to easily fix the noise on the 300ohm tap completely unless you discover it is not from the amp itself. Have a listen to some recordings of 120Hz buzz / ripple (I'm sure there are videos on YouTube) and see if it sounds the same as the noise in your amp.

I got the noise low enough where it's not annoying me like it was. Thanks for the tech overview. That is very helpful and interesting.

 

[HiFiHawaii808]

I wouldn’t suspect a ground loop hum as you would hear it at any tap.
Is it near a router or any computer equipment?
Have you tried different tubes?

No, isolated. Router is in other room. Computer is about 6 feet away as I type on it.

 

[HiFiHawaii808]

The buzz/hum/etc is exactly why I went with Solid State. I have a lot, a lot of experience with tubes after having played guitar for the better part of 20 years. I love my tube amps and have had probably more than 20 amps but they always had issues with buzz/hum and I spent many hours and many dollars trying to fix it to no avail. Maybe it's different with headphone amps vs. guitar amps but just didn't wanna risk that for the $$

The great thing about audio is that you can do both. You don't need to do either solid state or tube amp. I think a lot of people fear a tube amps because there is a bit of a learning curve to get it right. Tube rolling can be very daunting especially if you aren't confident about your own critical listening skills. I think if you sign up to get a ZMF headphone, you will need to test options in pads and sources to get the sound right anyway. So, in that regard, ZMF owners tend to be good candidates for tube amps especially since they sound so good with them.

 

[L0rdGwyn]

I would also add that designing a low noise tube amp is very doable if certain design "rules" are obeyed.

 

[SlothRock]

The great thing about audio is that you can do both. You don't need to do either solid state or tube amp. I think a lot of people fear a tube amps because there is a bit of a learning curve to get it right. Tube rolling can be very daunting especially if you aren't confident about your own critical listening skills. I think if you sign up to get a ZMF headphone, you will need to test options in pads and sources to get the sound right anyway. So, in that regard, ZMF owners tend to be good candidates for tube amps especially since they sound so good with them.

Totally agree with that. After I bought the Verite Closed, I needed to upgrade my Amp/DAC since I had been using the magni/modi schiit stack. I decided on a SS setup that can handle anything to start me out and provide flexibility for the VC's and any other HP I add to the stable. I'd be open to adding a tube amp down the road and having the best of both worlds . Most of the reason I don't right now is just budgetary with the explosion the VC/Amp/DAC caused to my wallet initially haha

 

[Monsterzero]

Tube rolling can be very daunting on your bank account

There, fixed it for you

 

[HiFiHawaii808]

There, fixed it for you

Agreed. Been there, done that with my Bottlehead crack. When I got a transformer output tube amp, I specifically got one that did not require a lot of tube rolling because of it.

 

[W3WEB]

Totally agree with that. After I bought the Verite Closed, I needed to upgrade my Amp/DAC since I had been using the magni/modi schiit stack. I decided on a SS setup that can handle anything to start me out and provide flexibility for the VC's and any other HP I add to the stable. I'd be open to adding a tube amp down the road and having the best of both worlds . Most of the reason I don't right now is just budgetary with the explosion the VC/Amp/DAC caused to my wallet initially haha

I just received my DNA Starlett amplifier and am one hour into listening with the VC. Moving from a Schiit Jotunheim to this is amazing. The biggest difference so far, is the vocals are much more defined. Can make out the words they're singing now. It's like a veil has been lifted. Know I need to burn things in a bit more, and my ears will get used to this; but wow the difference between SS and tube is stunning. Mind completely blown.

 

[zach915m]

I recently bought an Ampsandsound Rockwell tube amp primarily for use with my Verite Closed. What I really like about this particular tube amp is that it has 5 impedance taps of 8/16/32/100/300 ohms so that I can pair it with all of my headphones. But, I am getting quite a bit of noise and microphonics on the 300 ohm tap. It sounds best with it, but to reduce the noise, I dropped down to 100 ohms and adjusted the volume pot down and increased my pre-amp to get the right volume.

My question is this. Is there anything I can do to reduce the noise? I am using the ZMF 2K Copper cable. Would a shielded cable or some type of power conditioner help reduce noise? Thanks!

Easiest thing to start with is taking the RCA's out and seeing if the hum is there without a source plugged in. If it is, than the tubes can be next, if not then it may be USB or something environmental to another part of the chain.

I'm also lurking here now as some time in the not-so-distant future, I think I will finally get my hands on a VC

Can confirm. VC sounds like magic on the L0rd amps.

I just received my DNA Starlett amplifier and am one hour into listening with the VC. Moving from a Schiit Jotunheim to this is amazing. The biggest difference so far, is the vocals are much more defined. Can make out the words they're singing now. It's like a veil has been lifted. Know I need to burn things in a bit more, and my ears will get used to this; but wow the difference between SS and tube is stunning. Mind completely blown.

Starlet is great! Some of the more musical and refined sounds out there from a tube amp!

 

[Galapac]

I'm also lurking here now as some time in the not-so-distant future, I think I will finally get my hands on a VC

Yes! Your amps will love them…

 

[Barnstormer13]

After reading all the above posts, I feel very lucky that my tube amp is as quiet as it is.

It’s not as quiet as pretty much any SS amp or my hybrid amp, but inaudible at normal listening levels. Given my home ambient is around 30 dB, I’m not sure where that puts the noise, but I can’t hear it even when listening to music louder than I should. For me, that’s an easy trade for the euphonic sound of the amp.

 

[barbz127]

I recently bought an Ampsandsound Rockwell tube amp primarily for use with my Verite Closed. What I really like about this particular tube amp is that it has 5 impedance taps of 8/16/32/100/300 ohms so that I can pair it with all of my headphones. But, I am getting quite a bit of noise and microphonics on the 300 ohm tap. It sounds best with it, but to reduce the noise, I dropped down to 100 ohms and adjusted the volume pot down and increased my pre-amp to get the right volume.

My question is this. Is there anything I can do to reduce the noise? I am using the ZMF 2K Copper cable. Would a shielded cable or some type of power conditioner help reduce noise? Thanks!

What tubes are in it?

I have the Kenzie encore and all 12sl7/2c52 tubes were noisy when using the VC from the 300ohm.

The fix was to use a tube adapter and drop down to a 12au7 which I beleive has less gain than the 12sl7/2c52 and this dropped the noise floor considerably.

 

[HiFiHawaii808]

What tubes are in it?

I have the Kenzie encore and all 12sl7/2c52 tubes were noisy when using the VC from the 300ohm.

The fix was to use a tube adapter and drop down to a 12au7 which I beleive has less gain than the 12sl7/2c52 and this dropped the noise floor considerably.

6SL7 input tube
6AX5 rectifier
6B4G Power tubes (2)

 

[L0rdGwyn]

What tubes are in it?

I have the Kenzie encore and all 12sl7/2c52 tubes were noisy when using the VC from the 300ohm.

The fix was to use a tube adapter and drop down to a 12au7 which I beleive has less gain than the 12sl7/2c52 and this dropped the noise floor considerably.

So a 12AU7 is essentially equivalent to a 6SN7/12SN7, if the Kenzie Encore can take 12SL7, you could instead use 12SN7 without using an adapter, electrically equivalent to a 12AU7 (albeit with slightly different heater requirements) and no adapter required

If taking the same approach in the Rockwell, you would want to use a 6SN7 in place of the 6SL7. Again, same pinout, so no adapter required, but higher heater requirements.

However, even if the gain of the 6SN7/12SN7 is lower and will improve the noise floor in both amplifiers, the 6SN7/12SN7 and the 6SL7/12SL7 bias very differently, making the swap will not place the 6SN7/12SN7 at an ideal bias point as the circuit is designed for 6SL7/12SL7, so distortion may be higher and headroom lower than a circuit designed specifically for these tubes. You may want to check with Ampsandsound regarding bias point, as well as the different heater requirements.

You could ask if he would be willing to modify the Rockwell to use 6SN7 instead of 6SL7 if the primary use is for headphones and not speakers, meaning the excess gain is not needed. If the input tube is resistor loaded and cathode biased, should be a simple modification of swapping a few resistors. This would reduce the amplified noise floor and any coupled noise in the circuit as well as noise from the tubes themselves, but if the buzz is ripple from the B+ supply, that may not be alleviated completely by swapping the input tube and reducing gain as it affects the output stage as well.

Anyway, I know no one is asking for my opinion, but there are legitimate design reasons for noise, figured I'd try to take the mystery out of it.

 

[Klmahnn]

Here's a shot taken with a better camera.

I love to go over these pics now and again... this is a stunning pair/shot!