How much hum is normal for a new tube integrated amp?

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TommyC

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As per title, I've got some transformer hum from the Phasemation SA-1500 integrate amp. Clearly audible at 4 feet, but barely audible from my seating position of 8 feet. Speaker driver hum is less, but still audible within 4 feet.

I've tried some trouble shooting steps:
- Swapping back to the Accuphase is dead silent. No hum from the transformer or speakers. I cannot tell whether the unit is on or not. Completely silent
- Disconnecting the RCA input, no change
- Tried another outlet with supplied 2-prong power cord, no change
- Hum loudness stays the same regardless of volume or input selected

Hoping to get some feedback from tube experts here.

Thanks!
 
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TommyC said:
As per title, I've got some transformer hum from the Phasemation SA-1500 integrate amp. Clearly audible at 4 feet, but barely audible from my seating position of 8 feet. Speaker driver hum is less, but still audible within 4 feet.

I've tried some trouble shooting steps:
- Swapping back to the Accuphase is dead silent. No hum from the transformer or speakers. I cannot tell whether the unit is on or not. Completely silent
- Disconnecting the RCA input, no change
- Tried another outlet with a different power cord, no change
- Hum loudness stays the same regardless of volume or input selected

Dealer is away for 2 weeks, hoping to get some feedback from tube experts here.

Thanks!
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There should be zero hum. I would return it. Go back to your Accuphase.
 
Check your grounding, and tubes, before getting crazy. Consider trying to power it at someone else’s house.

I think “acceptable” hum is the kind you can just perceive with your ear right at the speaker. Worse with high efficiency speakers.

Consult the manufacturer.
 
this may not be related but half of Japan gets their power over 50hz lines the other half is 60hz. I was told depending on the manufacturer the xmfrs windings are optimized for 50 or 60hz depending on where the mfr resides. That said, Manley told us on a tour that winding power xmfrs for countries using 220-240v over a 50hz line freq often excerbate hum, ie. grounding issues.

I havent owned too many tube integrateds but have plently of tube separates where its hit and miss with xfmr hum., regardless of what grounding scheme i've tried. balanced lines help mitgate it.
 
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Many thanks for the responses. Tried a few more things without success. I’m investigating further with the dealer/distributor/manufacturer.

Good to know tube amps do not always hum and can be silent like SS gears.
 
I’ve owned a few tube amps and a little transformer hum seems pretty normal, especially compared to dead-silent solid state gear like Accuphase. If it doesn’t increase with volume and isn’t distracting at the listening seat, I’d say it’s within the normal range.
 
autretoir said:
I’ve owned a few tube amps and a little transformer hum seems pretty normal, especially compared to dead-silent solid state gear like Accuphase. If it doesn’t increase with volume and isn’t distracting at the listening seat, I’d say it’s within the normal range.
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What tube amps did you own that hummed? I've owned lots of tube amps over the years and I never had one that hummed.
 
Right from the MFG web site


A thorough low noise design​


This is thoroughly designed for a low-noise; it is designed with a rectification circuit with a ROHM high-speed switching diode and choke transformer for the high-voltage power supply and the 300B heater using DC ignition with a DC power supply. Furthermore, the power transformer is floating from the chassis using anti-vibration rubber used in the MA-5000. This suppresses the transmission of unwanted vibrations to the chassis and contributes to further reduction of noise levels
 
I can hear the hum from my listening position 8 feet away in between music, so slightly distracting. Going to try a DC blocker to see if that's the culprit. Dealer will also lend a VAC amp for me to try.
 
If the hum (or buzz) is coming from the amplifier, not the speakers, take the amp to a friends house in a different neighborhood. It may be AC power line related.
On the other hand, it may be a loose case cover or transformer mount.
 
TommyC said:
I can hear the hum from my listening position 8 feet away in between music, so slightly distracting. Going to try a DC blocker to see if that's the culprit. Dealer will also lend a VAC amp for me to try.
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Yes, Try a DC blocker. The transformer hum is usually due to DC. I can also hear hum from my Gryphon power amp but I have to put my ears next to chassis to hear it. Unfortunately, DC in the power line is unavoidable due to many SMPS appliances in the household.
 
I'm going to say it again-If you bought this amp new, send it back and get your money back. You don't need to have to put up with hum from a new tube amp.
 
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