SET headphone amp without hum?

When I first turned my WA6 on at full volume there was a very small hum. When I changed out the rectifier tube and the drivers tubes for 6SN7's and the Sophia Mesh Plate 247 tube it was dead quiet at full volume.

At normal listening levels there was no noticeable hum with any of the tubes.

Hope this helps!

RE: Yes, the Woo Audio...., posted on August 6, 2016 at 12:24:28
aarocks Audiophile Posts: 812 Joined: January 26, 2008	So if I have ground loop issues I will get hum from the WA6? I don't know if I do but I might and I rent. Do any SET headphone amps not produce hum even if there is a ground loop?

Ground Loop, posted on August 6, 2016 at 12:36:37
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	A ground loop of the type you're referring to would mean an external fault is injecting hum into the amplifier. No amplifier can protect you from that.

The two I own:, posted on August 6, 2016 at 17:14:33

Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005

Donald North Audio Stratus and Blue Circle SBH. The Stratus is a 2A3 SET. The SBH is SS-Single ended.

In many cases the hum will be due to a ground loop or rf interference, noise into the amp, all of which are fixable.

RE: Ground Loop, posted on August 6, 2016 at 17:17:13
Frihed89 Audiophile Posts: 15703 Location: Copenhagen Joined: March 21, 2005	In many cases, ground loops can be solved easily by connecting all equipment (including the computer, if you use one) into the same mains power source.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 07:32:11
genungo	All Donald North Audio SET headphone amps are "DC heated for black background - no noise". My DNA Sonett headphone amp is as quiet (or quieter) than any Solid State amp I've ever owned. Beautiful sound too.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 08:01:16
aarocks Audiophile Posts: 812 Joined: January 26, 2008	Will a DNA headphone amp hum through the headphones if it turns out I have a ground loop issue?

RE: SET headphone amp without hum?, posted on August 7, 2016 at 08:32:33
Frihed89 Audiophile Posts: 15703 Location: Copenhagen Joined: March 21, 2005	Yes.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 09:12:28
genungo	What "Frihed89" said. While DNA amps have vanishingly low self-noise, "ground loop" noise issues can affect any chain of amplification. So you need to get rid of those ground loop issues no matter what.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 10:15:02
aarocks Audiophile Posts: 812 Joined: January 26, 2008	How can I figure out whether I have ground loop issues or not? The Opera Consonance SET headphone amp I have now hums but it has a reputation for humming so I don't know if it's a ground loop issue or not.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 11:22:29

genungo

Some amps have a reputation for being "noisy" and/or more sensitive to ground loop issues than others. Humming can also be cause by things like internal wires or parts that are loosely attached.

A few years back and seemingly out of nowhere, my tube phono preamp developed a hum. When I opened up the case, I discovered that one of the input cable terminal nuts had loosened up. After I untwisted the wire and tightened the internal nut, the hum disappeared. Another time, I discovered that the phono section in an integrated amp that I had bought on the used market had a terrible hum. I looked inside and noticed that the casing internal ground wire attachment was painted metal rather than bare metal. After I scraped the black paint residue away and re-tightened the terminal nut, no more hum...

So, sometimes it's worth opening up the case and checking things out. Or if the amp is new and/or still under warranty, consider sending it back for a checkup.

If all else fails try contacting the manufacturer for advice on how to deal with hums and/or ground loop issues.

RE: SET headphone amp without hum?, posted on August 7, 2016 at 11:37:53
aarocks Audiophile Posts: 812 Joined: January 26, 2008	Thanks, I will do that. As far as SET amps that are less prone to hum due to ground loops, are those the ones that are said to be less noisy?

RE: Less noisy SET headphone amps, posted on August 7, 2016 at 12:15:07

genungo

Some amps have better power-supply filtration, better internal layout, and better internal grounding schemes than others do. These amps should generate the least amount of self-noise and should also filter out the most external noise, but I would guess that ALL components will perform better when potential ground loop problems are simply non-existent.

An easy way to eliminate (or check for) ground loops is to install two-prong "cheater plugs" on all components in your system that currently use three-prong plugs. If ground loop problems are solved this way, remove one cheater plug at a time until the offending component(s) have been identified. If humming disappears only when all components have cheater plugs, it might be best to have a certified electrician examine your house wiring so that the use of stock three-prong plugs might be resumed.

Simply making sure that all components are plugged into one single wall outlet often cures ground loop hum. Using too many outlets for the same system increases the chances of ground loop problems.

Sometimes too, simply reversing the orientation of one or more two-prong plugs (only some two-prong plugs are designed to allow for such a thing) in your system can uncover or eliminate humming issues and/or improve the quality of the sound. My old Rega CD player came with a reversible two-prong cord and in some instances it sounded slightly better with prong orientation one certain way.

Also, make sure that all interconnecting cables between components are firmly pushed into their respective sockets. Once you've checked all cable for tightness, slide your hands along the entire length of each cable while bending them back and forth slightly. A loose or broken wire and/or little bit of looseness anywhere can sometimes cause humming, so if the humming increases or stops when you test your cables this way the "problem" will have been solved...

Don't do it!, posted on August 7, 2016 at 22:47:44
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	Installing cheater plugs on all the gear is a good way to get killed. VERY bad advice here.

RE: Don't do it!, posted on August 8, 2016 at 06:01:06
genungo	"Cheater plugs" can be used to find out what and/or where problems are. I'm not recommending them for long term use.

RE: Less noisy SET headphone amps, posted on August 8, 2016 at 06:26:07

aarocks
Audiophile

Posts: 812
Joined: January 26, 2008

This system is made up of a computer and DAC and headphone amp and the computer and DAC are battery-powered. I've tried unplugging the battery chargers and using a cheater plug on the amp but the hum remains. This amp is said to hum generally so I guess I still might have ground loop issues. My subwoofer has a low hum that I can't hear from my listening position and one of the built-in lights here hums.

I'm trying to avoid buying a nice headphone SET amp that I can't listen to because I have a ground loop that I don't want to fix since I'm renting.

RE: Less noisy SET headphone amps, posted on August 8, 2016 at 06:56:41

genungo

Consider one of the Donald North Audio headphone amps if you want a quiet unit. They are not exactly cheap though - especially now that the old $1000 - $1200 "entry-level" Sonett is no longer being made by DNA. DNA's new entry level model, the Stratus, will cost you a cool $2700, but it truly is a versatile and great sounding SET headphone amp.

Look for a used DNA Sonett or DNA Stratus if you're on a budget. Or, shop around for another SET amp that has a similar reputation for low background noise. Decware also makes very nice headphone amps, check them out too.

RE: Don't do it!, posted on August 8, 2016 at 18:59:01
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	It only takes a split-second to get electrocuted. Cheater plugs aren't necessary. One of us should be able to walk him through the process; this problem might not even be a ground loop.

You need the Tube/DIY forum..., posted on August 8, 2016 at 19:05:38
Triode_Kingdom Audiophile Posts: 10049 Location: Central Texas Joined: September 24, 2006	I strongly recommend that you post a new thread asking for "assistance with hum" at the TubeDIY forum. That's where the most knowledgeable tube fanatics hang out. I could walk you through it here, but I don't want to do it alone. You'll get the benefit of a wide range of expertise over there. :)

RE: "It only takes a split second to get electrocuted", posted on August 8, 2016 at 19:09:54
genungo	Maybe, but that's what wives are for...

If you want a dead quiet amp and one of the best. . . , posted on August 9, 2016 at 15:44:52

John PA
Audiophile

Posts: 4019
Location: The lower 48.
Joined: August 27, 2000

sounding there is, I would get the micro Zotl 2. A David Berning design that is superb sound with plenty of power and high quality sound.

iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.

I totally agree with you!, posted on August 9, 2016 at 21:15:04
Cougar Audiophile Posts: 4593 Location: SoCal Joined: June 25, 2001	I just can't believe some of the bad/dangerous advice that is being posted lately on the AA and other forums. Especially with tube gear! It gets even more dangerous as you go up past 500Vdc. Some need to read the Safety rules on High Voltage equipment and how properly work with it.

A link is always helpful..., posted on February 12, 2017 at 16:04:35

Neil49
Audiophile

Posts: 8850
Location: Northern Virginia
Joined: June 13, 2003

David Berning's microZOTL 2.0

Headphone Heights

SET headphone amp without hum?

166.137.8.48