Hum from my Tube amp (300B) - Please help!

[Balle Clorin]

I still wonder which tube you replaced to fix the hum in BOTH? channels..
Or was that someone else?

If the amp was silent in became noisy it can be fixed. Some amps are inherent noisy and some just not compatible with the sources. Sometimes an amp can pick up noise from the environment, like a light dimmer or neighbouring component . Moving it and turning of all other electric use may lead you in the right direction.

 

[Saffy]

I still wonder which tube you replaced to fix the hum in BOTH? channels..
Or was that someone else?

If the amp was silent in became noisy it can be fixed. Some amps are inherent noisy and some just not compatible with the sources. Sometimes an amp can pick up noise from the environment, like a light dimmer or neighbouring component . Moving it and turning of all other electric use may lead you in the right direction.

I still wonder which tube you replaced to fix the hum in BOTH? channels..
Or was that someone else?
Was

Good advice, thanks. Fernando was guy that solved it with a tube swap. Be nice to know which tube. What is the chance that its one of my 300bs?

 

[Fernando]

...Por cierto, ¿qué tubo fue el culpable en su plataforma? [ /COTIZ]

I'm talking about a musical fidelity x-xan v2 that I had.

I changed it for one Mullard E88CC.

 

[raindance]

You say a cheater plug reduced the hum. With no source connected and the volume all the way down, how is the hum?

 

[Saffy]

Hi, after trying every process of elimination possible throughout my rig, in a end a cheater-plug on my amp solved the hum problem 99%. Why is that?, and how to I remove the source of the problem? OR, do I keep it as is, and add a low cost surge supressor to protect the amp? Thank you.

 

[Saffy]

You say a cheater plug reduced the hum. With no source connected and the volume all the way down, how is the hum?

Same significant hum without the cheater plug at low levels

 

[MakeMineVinyl]

Hi, after trying every process of elimination possible throughout my rig, in a end a cheater-plug on my amp solved the hum problem 99%. Why is that?, and how to I remove the source of the problem? OR, do I keep it as is, and add a low cost surge supressor to protect the amp? Thank you.

Is the audio ground connected to the chassis? If so, that might explain why using a cheater plug helped. Personally if this were my amp, I'd just leave the cheater plug in place. A surge protector isn't likely to do much unless you live in an area where there are frequent over-voltages, and even then, I wouldn't bother.

 

[Saffy]

Thanks, the amp is not grounded externally. The only reason I mentioned surge protector was to protect from over-voltages now that I'm using a cheater-plug. Can anyone recommend a budget one that doesn't mass with the sound?

 

[raindance]

Over voltage because you don't have a ground isn't a thing

 

[raindance]

If it hums with no inputs connected when it's grounded, but the hum goes away when you remove the ground by using a cheater plug still with nothing connected, then the grounding scheme of the amp is poorly designed. It happens. There's some theory and a whole lot of black magic in grounding schemes for low noise in a high voltage device like a tube amp.

 

[Saffy]

If it hums with no inputs connected when it's grounded, but the hum goes away when you remove the ground by using a cheater plug still with nothing connected, then the grounding scheme of the amp is poorly designed. It happens. There's some theory and a whole lot of black magic in grounding schemes for low noise in a high voltage device like a tube amp.

Thanks for clearing up my misconception! So I guess the ground removal has to do with personal safety. Though I still want a budget surge-supressor as I live in Florida - the lightening capital of the US. Any suggestions? Thank you.

 

[raindance]

Everything else in your system may need protection, but tube amps are pretty darn rugged. I usually recommend APC and go for the ones that regulate voltage like the Line-R.

 

[MakeMineVinyl]

Thanks for clearing up my misconception! So I guess the ground removal has to do with personal safety. Though I still want a budget surge-supressor as I live in Florida - the lightening capital of the US. Any suggestions? Thank you.

If you're concerned about lightning, I'd investigate a whole-house suppression installation. A big enough lightning strike doesn't give a damn about a wimpy protection strip.

 

[raindance]

@MakeMineVinyl - that's a true statement!

 

[Saffy]

Everything else in your system may need protection, but tube amps are pretty darn rugged. I usually recommend APC and go for the ones that regulate voltage like the Line-R.

Thanks again, I'm tempted go with the APC LE1200 Line-R 1200VA Automatic Voltage Regulatorn - two questions please: is 700 Jules enough, or better to go with their 2700 Jules 9 inputs unit (APC Black Rackmount Performance SurgeArrest 9 Outlet 120V) Again I don't want anything that could mess with the sound.. Appreciated!

 

[Saffy]

Then there is their cheap at $36 that has 4300 Jules (APC Performance SurgeArrest 10 Outlet with 2 Port 2.4A USB Charger 120V)
How important is the Line-R?

 

[MakeMineVinyl]

Again I don't want anything that could mess with the sound.. Appreciated!

A power strip doesn't have any mechanism to mess with the sound. The only way I can see this being a factor is if you were plugging in a very high power amplifier and the breaker on the power strip couldn't take the load.

 

[raindance]

Then there is their cheap at $36 that has 4300 Jules (APC Performance SurgeArrest 10 Outlet with 2 Port 2.4A USB Charger 120V)
How important is the Line-R?

The reason I suggested Line-R is because keeping the max mains voltage under control significantly increases the life of tube gear. The fact that it has surge protection is a bonus.

 

[Saffy]

The reason I suggested Line-R is because keeping the max mains voltage under control significantly increases the life of tube gear. The fact that it has surge protection is a bonus.

Thank you Raindance, I ordered the APC le1200, let's see what it can do. Question: My amp is rated at 115v (+/- 5%), therefore should I select the 110 or the 120v setting on the APC -given the APC's potential to step up or down by 10v when needed (100-120 OR 110-130v range respectively??) I also have a DAC and a Streamer voltage to consider. Thanks

 

[Saffy]

INPUT IMPEDANCE: 100K ohm (RCA)

OUTPUT IMPEDANCE: 4 ohm - 8 ohm

OUTPUT POWER: 8W into 8 ohms, CLASS A

DAMPING FACTOR: >3

FREQUENCY RESPONSE: 20Hz-20KHz -1dB

T.H.D.: <1% 20Hz-20KHz (REF. OUTPUT)

TOTAL GAIN: 32dB

INPUT SENSITIVITY: 300mV - 600mV

S/N: >90dB (HUM NOISE <1.5mV)

CHANNEL BALANCE: <1dB 20Hz-20KHz (MAX. VOLUME)

CHANNEL SEPARATION: >65dB 20Hz-20KHz

TUBE COMPLEMENT: 6N9P (6SL7) x 1

6N8P (6SN7) x 1

300B x 2

5AR4 (GZ34) x 1

POWER REQUIREMENT: AC 230V or 115V ±5%. 50~60Hz