Interesting change in what little "hum" I have left after Raven upgraded the grounding loop system. I just I'm OCD about a totally black background. I rearranged my room where now I sit 3 feet further back from speakers. For some reason I'm now out of reach of a low frequency "hum" that I can reacquire audibly if I lean forward those 3 feet! In the meantime the soundstage and detail etc. are all still excellent. Weird but nicely so. My volume goes up a tad at this increased distance which also helps. (I have an off topic quick question...does anyone know the best DB's on the Lascalas where they produce their best sound? 70? 80? 90?)
Hum on Tube Amp - Can't find source
I have a hum (60hz) I can hear on my speakers and it happens with my tube monoblocks (either of them). With or without interconnects, it even happens on either amp (have tried one at a time) with every circuit on the house tripped/disconnected, every other component disconnected from the wall (including the Internet/CaTV line) and no interconnects.
One amp has it as soon as it warms up whereas the other one is intermittent.
Hum X doesn't solve it, iFi Ground defender either, AVA HumDinger on powerline doesn't solve it either.
I have replaced the tubes and both amps were just tested at the factory. Replaced the circuit breaker, tightened every wire on the breaker box, checked and cleaned all connections to ground rod. Added a hum eliminator to the internet line.
Hum cycles a bit with the tube glow matching the cycles.
I'm waiting on the power company to come check the power coming to the house.
Thoughts?
145 responses Add your response
Put together any tube amp and the hyper efficient Klipsch Lascalas (or Klipschorn) and that efficiency will dredge the bottom of the amp's circuit mercilessly revealing the slightest hum, Paul Klipsch must not have minded this issue. (Early on he used tube amps until later Crown SS) Admittedly, all is forgiven and forgotten once the music is playing. However, pauses or gaps in the stream of music and HELLO there's the hum again! Being OCD, i.e. today's audiophile, and introduce said hum, and no matter how minuscule it can become deafening. Like most who are in this spot we have applied every tweak possible. And we have had a measure of success. But tube amps use tubes. Tubes are a moving target They are like candles gradually burning out. As a consequence, noise can increase here and there among the family of tubes as they interact with each other. The last couple days, after a month of nearly continuous (nearly) silent operation, no matter what I did, the hum had once again risen above my personal limit. After doing my due diligence and double checking the common culprits, I was defeated. Then on a whim I rotated the power tubes leaving the same but moving the big ones around. Hum GONE! Why is that? |
@ervikingo Hope your hum is still a non-issue. I'm anxiously awaiting the delivery of my first tube monoblock amps. I had a hum issue with my solid state amps, even with all new electric dedicated 20amp lines and audio grade outlets. Thank god a single humX fixed the issue, but I'm kinda nervous about my new amps since I won't be using dedicated and newly run outlets. I'm probably gonna have new 20amp lines run with audio grade outlets placed once I know where I'm gonna have my amps set up more permanently, but just kinda nervous. Well see... I'm also probably gonna ask the dealer I bought my amps through to lone me a puritan 156 with ultimate cable to A/B things should there be an issue. |
@atmasphere yeah… shopping for a gravel/adventure one now. |
My understanding is the two happiest days in the life of a boat owner is the day he buys it and the day he actually is able to sell it. I find bicycles are much easier to manage except for that N+1 thing (N= the number of bikes needed). |
@atmasphere being a guy in the land of 10k lakes, motor boating should be natural. 😎 (but it’s probably ice fishing season now,) I was pretty sure that the hum reducer gear, and power conditioning approach, was not likely to lead to a solution… and the amps not having RCAs hooked up precluded a ground loop being possible. And some version of an Ishikawa chart would have been helpful here.
In any case… it is a great outcome for the OP, and should be useful for others. |
@holmz The 12AX7 has more gain than a 12AT7. This can affect the amount of feedback that exists in the amplifier and can also affect something called 'phase margin'. If the amp was designed to use a lot of feedback and was a bit to close to the limits of its phase margin, by adding the slight extra gain of the 12AX7 it could have pushed the amp over the edge. So an oscillation is entirely possible, simply on account of the 12AX7. This is why it can be so important to use the tube for which the amp is designed. |
Yes, with the significant other "quarantining" due to Covid, I moved to the music room since last Monday! Have put hours enjoying music! The (financial) downside is that i hit the vendors: - Have 2 quads of EL34's scheduled for delivery today. With those, every single tube on the amps is new - Waiting for the PS Airlens to be released so in the meantime I ordered (and received) a Wiim Pro - Ordered a budget DAC to go with it (Topping D90SE MQA) which should be delivered later in the week Currently running the Wiim to my trusty but dated spec'd Theta Gen V and alternatively to the onboard DAC on a Lexicon MC-1. Have to say, the Wiim sounds good! On A/B tests from my CD transport to the same DAC there is a discernible difference (improvement).
|
@ervikingo, so glad to hear that the hum is gone. Now it’s time to enjoy some music. |
@jea48 since we are on this, any recommendations on tubes or suppliers? 12AT7, 7044, EL-34, KT77? |
Monday morning update. I couldn't wait for the "good tubes" to come for testing. I ordered one from Amazon (overnight delivery!) and the noise is completely gone. Its scary quiet! I ordered new 7044 as one of them is not up to par (still some noise). I moved the 12 AT7 from one amp to the other and there was noise on the other amp; moved the 7044 from the quiet amp to the other and the noise is gone. Huge lessons learned: - there are a lot of enthusiasts out here who are willing to help - @atmasphere is an awesome resource - start with the basics; I have spent weeks and $$$ chasing after the noise and never thought to check if the prior owner had used the proper tubes I'll post again once both 7044 and 12AX7 have been replaced with the 12AT7. Please accept my most sincere thanks for your help (and for the humor... trolling with the motorboating sound...!) |
Here’s some highlights from the jea48 linked Tubes Asylum discussion: -check the bias as they power up, and let them settle in for a bit (like 20 mins) for a final check. -do not buy new tubes for hi-fi amps from guitar tube suppliers. Buy them from hi-fi tube dealers. Tubes (even matched quartets) sold by most guitar outlets are specially selected to distort early (low transcoductance tubes), therefore they run out of bias adjustment pretty quickly on a HI-Fi amp and there goes another tube! -Manley has checked out the amps (one of them twice) and says there isn’t anything wrong with them. -I have one Snapper that has been back to the shop once. It seems to be holding its own ok in terms of not blowing tubes. The other amp is a different story. It just came home from its second trip to the shop and after two hours of use, blew its B+ fuse and two of the tubes, separating the center post of the two tubes from the tubes themselves. -Try plugging the monoblocks directly into the wall outlet and check the bias to see if you have better bias stability (bypassing any power conditioners). -When you pull output tubes in and out on a regular basis, we have a tendency to stretch out the tube pins and even can cause tiny stress cracks on circuit board..Now this leaves you with low bias or intermittent bias or no bias voltage many times therefore causing tubes to burn up. I don’t know how much technical knowledge you have on this kind of stuff, but I would re-solder the tube socket connections and tighten the pins inside the sockets or even replace the sockets with better ones -Manley’s have not-so-good sockets in them. -yanking tubes in and out of both amps, he could very well have bad sockets in both or loose solder connections at the very least -We are rebiasing the amps each time we replace the tubes. We recheck the bias every few hours and the amps have never held bias well. We are terrified of damaging the output transformers, power supplies, speakers, and everything else. My husband and I have been audio enthusiasts for almost 30 years and the hobby is becoming more stressful than fun with the problems we have had with these amps. We have spent many thousands of dollars (money we don’t have) replacing tubes by the octet since we bought the amps, not to mention the shipping back to Manley.
|
| Post removed |
| Post removed |
| Post removed |
With the motorboating clue, it would not be unthinkable that those small tubes are involved. |
Another good point. The manual states: Recommended Speaker Load: Optimized for 5 ohms Do you know what impedance your speakers are rated ervikingo?
To me, this is the most concerning factor in this whole scenario. Here’s a few other tidbits from the manual: -For the power tubes in our amplifiers, after a few years if you notice a small revolt going on where several of the output tubes are misbehaving or getting hard to bias, you might consider doing a full re-tube. -Three tube types that are electrically and plug-socket compatible with the 12AT7A dual triode include the 6021, 6679, and the ECC81 (I find it a little interesting that they made no mention of a 12AX7 here). -Never operate the amplifier without a speaker load, or suddenly disconnect the speaker load while the amplifier is producing a signal. This risks punch-through of the enamel insulation covering the transformer’s internal magnet wire. Permanent damage to the output transformer may result -Additionally, it is best to cut power to the Snapper when not in use rather then leaving the power on indefinitely. This will enhance tube and system life.
|
Have you tried connect a different pair of speakers on your Manley Snappers?
|
I didn't read every post, just the first half of them. I'm going to say that it's the transformers themselves. I had this problem with my Luxman integrated. It was dead quiet for several years after I bought it, then developed a low hum. It is always the same, comes from the amp, not the speakers, and is independent of any controls or devices. The fix is new transformer(s), which is expensive, and not a guaranteed remedy. |
@dpop I sent it because when I received them they had non OEM inline fuse holders and one was DOA. I spoke with the seller and agreed that they should go to Manley for repairs/return to original configuration and any other repairs. I paid for checkup and a couple of tubes that had the key broken. Manley have been great. They have followed the journey on this and offered suggestions. The non conforming tube was brought up by them today/yesterday. |
I’m assuming you sent it in, because of this problem? If it came back with a clean bill of health from Manley, it sounds like this problem was not taking place when they had it on the bench, otherwise I’m quite sure Manley would have contacted you about it (yes, no, maybe?). |
@zombiedad I should have some tubes delivered tomorrow for the swap. Let's hear! |
@zombiedad swapped the KT77 also swapped the 7044 and 12ax7 from one unit to the other. I suspect that 12ax7 is the problem. Speaker wires are AQ Rocket directional 18" long |
It looks like the one I posted. Mine is a TPS3A111000 (no superseded by TPS3A111002) https://mall.industry.siemens.com/mall/en/us/Catalog/Product/?mlfb=US2%3ATPS3A111002 Thus: voltage code: 120/240V, 10,3W 100kA per phase EMI/RFI filtering (sine wave tracking), Ground integrated monitoring, Protection modes L-N, L-G, N-G, L-l (whatever all of that means!)
|
Wow, these tube amps are more sensitive then I thought. Come to think of it, I was really into tube headphone amps for a while. I discovered that they too were very sensitive to headphone impedance, when it came to low level hum produced by the amp. I weighted the issue, and concluded that the headache just wasn't worth it. I was also many times hearing sporadic plinks, plunks, and noise bursts with tubes, and that drove me a little crazy too. |
That happened to me a month ago, I heard the hum through both of my speakers, very annoying. That hum noise was from my KT88. Later I swapped my tubes to another KT120. Noise is gone, so quiet. That was my fixed. Nothing related to any ground, power conditioner. If you have extra set of tubes, try swap it and see if that helps.
|
@holmzyou beat me to it...
It kind of sounds like a low frequency motorboating oscillation. This may be off the wall, but I seem to remember reading a thread several years ago, can’t remember if it was on Agon or AA where a guy was having an oscillation problem with a tube amp. Just going from memory someone asked what speaker wires he was using. What ever manufacturer, type, speaker wire it was it was causing an impedance mismatch for the output transformers for the amp. If it was here on Agon I would bet the Late @almarg chimed in and was the one that solved the problem. Might be worth it to try a cheapo zip cord 14/2 cable and find out for sure. |
When it comes to AC power, audio gear, or electronics or electricity in general, I have never seen or heard anything like that ever before. Thanks for sharing the video! Wow, WHAT is going on here? And both amps do this?! Plugging one of these in at a completely different location should also tell us something. Has that been tried yet?
Great suggestion! Since you can’t just pull the electric company meter to simulate a power outage, the ATS would need to have a special function switch to power up and transfer the load. Not all ATS’ have this switch and function, but it’s worth a look. Many generators and ATS’ have test switches, but don’t always transfer the load.
Crazy.
Good call! Let’s see. Hopefully it’s the TPS3A11 version, if the service drop is single phase. |