Hey I have a Massdrop Cavalli tube hybrid headphone amplifier with an Electro harmonix 6922he valve and the left channel has like ssshhhhhh noise it’s like a faint white noise you know the noise that some powered speakers have naturally. You see it’s only in the left channel and I was wondering what would cause it? With nothing playing through the rca I turn it up about half volume and it nearly goes away but when I turn it up further to 100% it slowly comes back as I turn it up.
Any thoughts on this?
Cheers
Any thoughts on this?
Cheers
This sounds like "Johnson"/thermal noise coming from the volume control as it varies illogically according to the volume setting.
I take it you have shorted out the input RCA first not left it open ?
If you can disconnect that channels volume control and fit a low noise resistor in its place at the worst setting resistance as a test .
Obviously if its full volume (100 % ) just solder in a shorting wire .
Make sure you do NOT keep the volume control in circuit !
I take it you have shorted out the input RCA first not left it open ?
If you can disconnect that channels volume control and fit a low noise resistor in its place at the worst setting resistance as a test .
Obviously if its full volume (100 % ) just solder in a shorting wire .
Make sure you do NOT keep the volume control in circuit !
Thankyou so so much for your reply
“This sounds like "Johnson"/thermal noise coming from the volume control” does that mean it’s a common issue?
No I haven't shorted the rca, it does it when nothing is connected and also when a cd player is connected but I'll short it to see what happens.
‘If you can disconnect that channels volume control” as in remove the pot?
“Make sure you do NOT keep the volume control in circuit” is that referring to just the pot or all the components to do with the volume?
Again thankyou I really appreciate it
“This sounds like "Johnson"/thermal noise coming from the volume control” does that mean it’s a common issue?
No I haven't shorted the rca, it does it when nothing is connected and also when a cd player is connected but I'll short it to see what happens.
‘If you can disconnect that channels volume control” as in remove the pot?
“Make sure you do NOT keep the volume control in circuit” is that referring to just the pot or all the components to do with the volume?
Again thankyou I really appreciate it
Just unsolder the first two connections to the volume control and solder in a resistance between the input tag and the slider variable control tag just leaving the last earth tag in place .
That should bypass the carbon track of the volume control and allow you to listen for any noise --use a low noise metal film resistor.
The input must be shorted so that you can eliminate any noise coming from it.
That should bypass the carbon track of the volume control and allow you to listen for any noise --use a low noise metal film resistor.
The input must be shorted so that you can eliminate any noise coming from it.
I have shorted the rca input and that doesn’t change a thing, I have removed the volume pot and put resistors in and it still has the hiss/static in the left
I’m wondering if it is the valve? It doesn’t sound like valve issues as it is like a non changing hiss/static but I could be wrong? It does get softer then louder when the volume pot turns up.
Any other things I can try?
Thanks so much
I’m wondering if it is the valve? It doesn’t sound like valve issues as it is like a non changing hiss/static but I could be wrong? It does get softer then louder when the volume pot turns up.
Any other things I can try?
Thanks so much
Why would there be "Johnson"/thermal noise coming from only one channel of the volume control? I would think that if it's that type of noise than it has to come out of both channels, unless the resistance of the left channel part would have gon up a lot. But than you would have to hear a difference in volume between the left and the right channel.
To TS: It could be oscillation on a very high frequency (well over 20 kHz). This can cause audible hiss/noise. Are there grid stoppers at the grids of the 6922? Did your amplifier have this problem since you got it?
Its a stereo amp --its has TWO volume controls ( I am looking at the circuit diagram ) so why should it not be considered as a potential fault if the noise could be coming from ONE volume control or do you think if one channel of any stereo amplifier is faulty the other channel must have the same fault ?
I'm just asking. You wrote in your bio that you are a quadruple engineer. I'm just an amateur.
I wrote about the left and the right part of the volume control. So I wrote about a stereo amplifier with a stereo volume control. It's unusual to talk about two volume controls if one is talking about the volume control of a stereo amplifier. And why would a modern headphones amplifier be a mono one?
I'm a bit puzzled that already in post #2 you are advising TS to start to disconnect the volume control. I would think that it's better to first analyze the problem better, or atleast try less drastic possibilities first (like changing the tube).
I wrote about the left and the right part of the volume control. So I wrote about a stereo amplifier with a stereo volume control. It's unusual to talk about two volume controls if one is talking about the volume control of a stereo amplifier. And why would a modern headphones amplifier be a mono one?
I'm a bit puzzled that already in post #2 you are advising TS to start to disconnect the volume control. I would think that it's better to first analyze the problem better, or atleast try less drastic possibilities first (like changing the tube).
Repairing audio equipment requires a question and reply when its done virtually as I don't have the component in front of me.
The noise he was complaining of sounded like "Johnstone noise " -- if you don't like the way I check something out then that's your business .
Its easy after the event to come on and criticize somebody , that its not that fault fair enough at least that's eliminated, if it was in front of me maybe I would chose another test if I actually heard the noise ---it must be "wonderful " to be perfect and its then amazing that I am not alone in not getting it right first time in DIY Audio others with equivalent abilities don't get it right first time but I don't lower myself to criticize them otherwise this website would be full of flame wars .
The noise he was complaining of sounded like "Johnstone noise " -- if you don't like the way I check something out then that's your business .
Its easy after the event to come on and criticize somebody , that its not that fault fair enough at least that's eliminated, if it was in front of me maybe I would chose another test if I actually heard the noise ---it must be "wonderful " to be perfect and its then amazing that I am not alone in not getting it right first time in DIY Audio others with equivalent abilities don't get it right first time but I don't lower myself to criticize them otherwise this website would be full of flame wars .
Easy, easy . .
We also have the challenge of *estimating* the technical expertise of the OP, how many different tests have been tried and eliminated already, and which ones.
To me (and granted it's just me), PCL200's *I'm a bit puzzled ..* paragraph falls well short of overt criticism -- more of an observation; possibly even an invitation to explain.
The high school gym coach would say, "Everybody take two laps", and maybe add a cleansing breath.
Cheers
We also have the challenge of *estimating* the technical expertise of the OP, how many different tests have been tried and eliminated already, and which ones.
To me (and granted it's just me), PCL200's *I'm a bit puzzled ..* paragraph falls well short of overt criticism
-- more of an observation; possibly even an invitation to explain.The high school gym coach would say, "Everybody take two laps", and maybe add a cleansing breath.
Cheers
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Have you tried swapping the tube? It sounds like one of its triode sections has gone cranky.
While Johnson noise (aka thermal noise) is certainly a thing - just as many others types of noise - it would impact both channels equally. At least assuming the two channels are identical. So if you only have noise in one channel, the source is a bad component, not a noisy design.
Tom
While Johnson noise (aka thermal noise) is certainly a thing - just as many others types of noise - it would impact both channels equally. At least assuming the two channels are identical. So if you only have noise in one channel, the source is a bad component, not a noisy design.
Tom
But it is possible to have two channels, each compliant with the same schematic, that due to chassis layout have differing susceptibility to EMI.
In a single-supply, two channel build, it's very likely that one channel's more sensitive nodes will end up closer to an incoming power line lead -- say, going to the power switch on the front panel.
Cheers
In a single-supply, two channel build, it's very likely that one channel's more sensitive nodes will end up closer to an incoming power line lead -- say, going to the power switch on the front panel.
Cheers
Trying to shake this thread back to life since I´m having the same problem. A not so faint static hiss on the right channel with som crackles and pops sprinkled in. It is distinctly audible at quiet passages in music and remains after swapping out the tube. Also it can vary somewhat in strength over time if the amp is left on. The volume pot also crackles between ten and fifteen and on the last stretch of the turn a ground hum magically appears. I have not opened it up or done really anything else than changing the tube and shorting the RCA:s. It annoys the hell out of me since I really like the way it sounds overall.
Are these issues of the exact same model, commercially produced unit? Pictures, schematics available? Do you know if you have noisy power otherwise?
A reference range would be handy, when you say, for example
I'm familiar w/'turned up to 11', but '15' is new to me.
Cheers
A reference range would be handy, when you say, for example
Generally, crackles from a volume pot are a different problem -- with a different solution.vilding said:
I'm familiar w/'turned up to 11', but '15' is new to me.
Cheers
I heard time-varying noise coming from guitar amps in the past that I originally attributed to the input tubes. Later turned out after trying a couple of different types of power conditioners that it was power line noise getting into the circuitry. One power conditioner cleared it up fine, the other didn't help at all.
Yup, no end of surprises when it comes to "power conditioners". Glad at least one of them worked.
Had to wind my own when a couple of early (1978) Bryston 4B's HATED the power at 'the fancy new club'. I don't think there was a lamp circuit in the entire joint that wasn't on a crappy dimmer. As far as I know, a "power conditioner" was not commercially available at the time (1979-80).
Cheers
Had to wind my own when a couple of early (1978) Bryston 4B's HATED the power at 'the fancy new club'. I don't think there was a lamp circuit in the entire joint that wasn't on a crappy dimmer. As far as I know, a "power conditioner" was not commercially available at the time (1979-80).
Cheers
🤣🤣🤣 Yeah... I hadn't gotten my morning coffee yet.... Noisy pot between about ten'o'clock and three'o'clock, might try some contact spray. It's the Massdrop produced and sold unit, and all is stock and untampered with except for the tube that's a temporary cheapo replacement, with no change in noise. Other people have complained about similar noise, sometimes from the right channel, sometimes from the left. It's like tube hiss, but amplified and interspersed with slight crackling. Left channel is close to dead silent, only the faintest hiss, barely audible.I'm familiar w/'turned up to 11', but '15' is new to me.
I couldn't find any schematics, but https://www.audiosciencereview.com/...be-hybrid-cth-and-jds-o2-headphone-amps.3928/
My mains aren't noisy per se, but I sure wouldn't mind having a separate group for the audio stuff.