Massdrop x Alex Cavalli Tube Hybrid Amp (CTH) - Dropping Monday
Nov 23, 2019 at 1:43 PM Post #1,216 of 1,389
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Not sure if this is the right place or time to jump in here, but here goes...

HISS

I've had my CTH since April of 2018, and I love it. I've recently moved it from home to the ofiice, and I'm getting hiss from my Meze 99 Neos and my Beyer DT-880 32 ohm headphones plugged into the 1/4" jack.The hiss decreases as I turn the volume pot up. I never noticed hiss before on any headphone I've plugged into this amp. Is it possible that the stock tube has gone south? Or is it something gnarlier like power supply/grounding? Something else? Any troubleshooting advice is appreciated.
 
Nov 23, 2019 at 5:15 PM Post #1,217 of 1,389

Mark Bajkowski

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Not sure if this is the right place or time to jump in here, but here goes...

HISS

I've had my CTH since April of 2018, and I love it. I've recently moved it from home to the ofiice, and I'm getting hiss from my Meze 99 Neos and my Beyer DT-880 32 ohm headphones plugged into the 1/4" jack.The hiss decreases as I turn the volume pot up. I never noticed hiss before on any headphone I've plugged into this amp. Is it possible that the stock tube has gone south? Or is it something gnarlier like power supply/grounding? Something else? Any troubleshooting advice is appreciated.

As a general rule, hiss in a tube-amp stage can relate to ineffective filtering and often results from an ineffective/disconnected capacitor somewhere. Did you drop or banged the unit during the move? Even if not, I would actually tap it quite strongly to see if there is any intermittent change of the hiss level.
 
Nov 24, 2019 at 11:03 AM Post #1,218 of 1,389
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As a general rule, hiss in a tube-amp stage can relate to ineffective filtering and often results from an ineffective/disconnected capacitor somewhere. Did you drop or banged the unit during the move? Even if not, I would actually tap it quite strongly to see if there is any intermittent change of the hiss level.

No, I'm pretty sure I didn't bump or bang it, but I will give it a solid thump Monday morning when I go back into the office.
 
Nov 24, 2019 at 11:23 AM Post #1,219 of 1,389

PaganDL

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Not sure if this is the right place or time to jump in here, but here goes...

HISS

I've had my CTH since April of 2018, and I love it. I've recently moved it from home to the ofiice, and I'm getting hiss from my Meze 99 Neos and my Beyer DT-880 32 ohm headphones plugged into the 1/4" jack.The hiss decreases as I turn the volume pot up. I never noticed hiss before on any headphone I've plugged into this amp. Is it possible that the stock tube has gone south? Or is it something gnarlier like power supply/grounding? Something else? Any troubleshooting advice is appreciated.


@Allegro maestoso,

What @Mark Bajkowski stated is likely possible as there are always possible issues with electronic parts, especially if something has been dropped but from the sounds of things, it is more than likely just the [I/]'normal'[/I] hiss tubes make.
Electro Harmonix is the CTH stock tube & well known for being noisy to some degree though this will also depend on head gear used, eg impedence & sensitvity, how loud you listen as well as how quiet the media you are listening to is.
In general, depending on circuit design & implementation, tube amps noise output can vary from mains point to mains point too which might explain why you hear more noise now on your slightly more sensitive headphones.

Things to note about tube amps & tubes in general :

1. No matter the tube & or amp, regardless of cost, they will all make some noise or hiss, as that is the nature of tubes, there is no silent tube but there are definitely ways the tube noise can be reduced.
2. The tube type is an obvious primary factor as some tubes & some tube brands are more noisy than others, eg, Mullard, Genelax, Jan, JJ Electronics, Tung Sol, Electro Harmonix, etc
3. Noisy tubes can also have high gain &/or microphonics (eg, that bell like sound when a tube amp is tapped, regardless whether the amp is on or not & head gear &/or speakers are plugged in)
4. Some tube suppliers can also adjust Tube Gain, Microphonics, Noise as per customer request.
5. Tubes which are known to be noisy are generally also more commonly used in guitar amps as those tubes tend to be easily available as well as affordable to a degree so I suggest searching for tubes which have low noise, low gain (unless you want that) & low microphonics.
6. As stated above, electronics & other components used as well as design implementation plays a significant part in tube amp design or any electronics for that matter, though this doesn't mean a fairly quiet amp, tube or solid, has to be ridiculously expensive just because.
But some manufacturers would like you believe this is true.

There are ways to reduce general [I/]'normal'[/I] hiss from tubes though it will depend on how far you want to take things to reduce that hiss.

1. Have a good powerboard &/or mains outlet with good EMI/RF protection &/mitagation is perhaps the most basic step one can take.
2. Try a less noisy tube.
3. Change your cables &/or power supply to see if this makes a difference though this will depend on your budget & how much you believe in tuning sound.


Hope you find this useful, feel free to ask more if you need.

Hope you have a great day !
 
Nov 24, 2019 at 4:22 PM Post #1,220 of 1,389
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@Allegro maestoso,

What @Mark Bajkowski stated is likely possible as there are always possible issues with electronic parts, especially if something has been dropped but from the sounds of things, it is more than likely just the [I/]'normal'[/I] hiss tubes make.
Electro Harmonix is the CTH stock tube & well known for being noisy to some degree though this will also depend on head gear used, eg impedence & sensitvity, how loud you listen as well as how quiet the media you are listening to is.
In general, depending on circuit design & implementation, tube amps noise output can vary from mains point to mains point too which might explain why you hear more noise now on your slightly more sensitive headphones.

Things to note about tube amps & tubes in general :

1. No matter the tube & or amp, regardless of cost, they will all make some noise or hiss, as that is the nature of tubes, there is no silent tube but there are definitely ways the tube noise can be reduced.
2. The tube type is an obvious primary factor as some tubes & some tube brands are more noisy than others, eg, Mullard, Genelax, Jan, JJ Electronics, Tung Sol, Electro Harmonix, etc
3. Noisy tubes can also have high gain &/or microphonics (eg, that bell like sound when a tube amp is tapped, regardless whether the amp is on or not & head gear &/or speakers are plugged in)
4. Some tube suppliers can also adjust Tube Gain, Microphonics, Noise as per customer request.
5. Tubes which are known to be noisy are generally also more commonly used in guitar amps as those tubes tend to be easily available as well as affordable to a degree so I suggest searching for tubes which have low noise, low gain (unless you want that) & low microphonics.
6. As stated above, electronics & other components used as well as design implementation plays a significant part in tube amp design or any electronics for that matter, though this doesn't mean a fairly quiet amp, tube or solid, has to be ridiculously expensive just because.
But some manufacturers would like you believe this is true.

There are ways to reduce general [I/]'normal'[/I] hiss from tubes though it will depend on how far you want to take things to reduce that hiss.

1. Have a good powerboard &/or mains outlet with good EMI/RF protection &/mitagation is perhaps the most basic step one can take.
2. Try a less noisy tube.
3. Change your cables &/or power supply to see if this makes a difference though this will depend on your budget & how much you believe in tuning sound.


Hope you find this useful, feel free to ask more if you need.

Hope you have a great day !

This is excellent advice. Thank you or taking the time to reply in such good detail. It's comforting to know that nothing is terribly wrong, that some level of noise can be expected, and that there are a number of variables in play. Funny that I never noticed it before, but I think it was probably the Mezes that got me to hear it obviously - they are quite sensitive, and the closed backs really keep out ambient noise. I tried my Sendy Aivas (1/4" and XLR) and Nighthawk Carbons yesterday, and it does seem to correspond to headphone sensitivity - the Hawks were quieter than the Mezes, and the Aivas were the best of the three, especially from the XLR out. I've used my Elegias a lot with this amp, too, and the noise is virtually inaudible. Also, it may be psychological, but it seems like the hiss gradually diminishes the longer the amp is on.

I'm not in a rush to spend money (extravagantly or modestly) on a power supply, AC cleaner, or the legendary perfect tube. Maybe some day, one step at a time, but for now, I'll be fine learning to accept and maybe even appreciate the sound as is. And oh yeah, give it a good (careful) thump.
 
Nov 24, 2019 at 5:25 PM Post #1,221 of 1,389

Mark Bajkowski

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...It's comforting to know that nothing is terribly wrong, that some level of noise can be expected, and that there are a number of variables in play. ...

Based on your last comment, I suspect your noise is acceptable but it also introduces a possibility of environmental interference like EMF noise in your office -- offices tend to be more saturated with industrial noise -- and those may include fluorescent lighting banks, switching power supplies, any devices with electric motor, even inductive stoves, fans, etc. Higher-frequencies get into an audio path through inductive coupling from the proximity of an EMF emitter which sometimes can not be fully controlled by amp as in a case of substandard grounding, not to mention the CTH has its vacuum tube quite exposed. Maybe also move the amp to other areas in your office just to detect any noise variation.
 
Nov 26, 2019 at 12:13 PM Post #1,224 of 1,389

Yh173088

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Likely a dead tube, did you turn it off when you stopped using it? I've had a tube die in one months time in my CTH
I did but previous owner had mentioned he had the unit for around a year . I’m hoping it’s just the tube . When u have a dead tube , does it not make any sound at all ? I’m new to tubes so I am not really sure what to expect in such a situation .
 
Nov 26, 2019 at 12:31 PM Post #1,225 of 1,389

Guidostrunk

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No sound if the tube is dead. Does the tube look kinda white at the top?
I did but previous owner had mentioned he had the unit for around a year . I’m hoping it’s just the tube . When u have a dead tube , does it not make any sound at all ? I’m new to tubes so I am not really sure what to expect in such a situation .
 
Nov 26, 2019 at 12:38 PM Post #1,226 of 1,389

Guidostrunk

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Just switched to a CBS Hytron 5692 , red base(rugged version of 6sn7). Good God is this tube fantastic! Kinda pricey but deals can be had on Ebay. I scored one last week for $40 shipped.
This was my second favorite tube when I had my Woo Wa6. Only bettered by the GEC CV181.
 
Nov 26, 2019 at 5:02 PM Post #1,229 of 1,389

Yh173088

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Yep, at the top. If its white it's toast. I have a stock tube if you want it. PM me your addy and I'll ship it out to you tomorrow.
Thank you !
I don’t live in the US , I live in Singapore so should be easier if I try getting from my local store . But thanks again for clarifying how to identify a busted tube .
I only had it for a few hours but I did enjoy listening on it .
 

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