Ground loop?

[olds1959special]

I’m noticing a faint buzz in my right speaker. Is there a way to fix this?

Setup is:
SMSL DO100 Pro - Fosi P4 - Kenwood L-05M's - Vandersteen 2Ce Sig II

I’m in an old building and some outlets are ungrounded, so I ran an extension cord from a grounded outlet and hooked up a small power conditioner, which my stereo components work off of.

I tried an Hum X / Ebtech hum remover on my DAC but it didn’t help. The amps and pre-amp are two prong.

Should I try hooking the right amp up to the left amp through the switched input?

 

[DVDdoug]

It may not be a ground loop. Without a power ground there's not much chance of a "loop".

Unplug the inputs to the power amp (temporarily turn it off when plug & unplug the RCA connectors). If the buzz is still there with nothing connected (and with no input-ground) the problem is with the amp itself.

When you plug it back in, reverse the left & right connections and if the buzz appears in the opposite channel it's coming from the preamp or somewhere else upstream.

 

[solderdude]

1: disconnect the inputs of the power amps (preferably short the RCA inputs). Connect the speakers. Is there any hum ?
if no connect an RCA between both power amp inputs.
2: If there is no hum go to next step.
3: power the P4 and set the volume control to '0' and do not connect anything else to the P4
Connect P4 only to 1 power amp via RCA. Is there hum in the connected amp ?
If not only connect the other amp. Is there hum in the connected amp ?
If not connect both power amps to the P4. Is there hum in either channel ?
4: Connect SMSL only to the P4 and only the mains from the SMSL. Is there any hum ? (volume still fully down (0)).
5: Turn up de volume of the P4... is there hum noise ?
if not play music via BT. all O.K. ?
6: connect source to SMSL (no music playing still on BT input)
7: switch SMSL to wired input source.

When does the hum start ?

 

[olds1959special]

1: disconnect the inputs of the power amps (preferably short the RCA inputs). Connect the speakers. Is there any hum ?
if no connect an RCA between both power amp inputs.
2: If there is no hum go to next step.
3: power the P4 and set the volume control to '0' and do not connect anything else to the P4
Connect P4 only to 1 power amp via RCA. Is there hum in the connected amp ?
If not only connect the other amp. Is there hum in the connected amp ?
If not connect both power amps to the P4. Is there hum in either channel ?
4: Connect SMSL only to the P4 and only the mains from the SMSL. Is there any hum ? (volume still fully down (0)).
5: Turn up de volume of the P4... is there hum noise ?
if not play music via BT. all O.K. ?
6: connect source to SMSL (no music playing still on BT input)
7: switch SMSL to wired input source.

When does the hum start ?

I pulled out the rca and just turned on the right amp and it buzzes still.

 

[solderdude]

Defective amp.... assuming the other ones are quiet (enough).
Possibly needs a recap ?

Amir's measurements also showed quite a lot of hum.

 

[olds1959special]

Defective amp.... assuming the other ones are quiet (enough).
Possibly needs a recap ?

Amir's measurements also showed quite a lot of hum.
View attachment 459783

I plugged the other amp into the same speaker and it was silent with no rca input. I took the defective amp into the amp repair shop, hopefully I’ll hear from them with a diagnosis this week.

 

[Roland68]

I’m noticing a faint buzz in my right speaker. Is there a way to fix this?

Setup is:
SMSL DO100 Pro - Fosi P4 - Kenwood L-05M's - Vandersteen 2Ce Sig II

I’m in an old building and some outlets are ungrounded, so I ran an extension cord from a grounded outlet and hooked up a small power conditioner, which my stereo components work off of.

I tried an Hum X / Ebtech hum remover on my DAC but it didn’t help. The amps and pre-amp are two prong.

Should I try hooking the right amp up to the left amp through the switched input?

For amplifiers that are about 45 years old, I would prophylactically clean the circuit boards on both monoblocks (top and bottom with isopropyl alcohol), replace all smaller capacitors with current ones, check the large capacitors and replace them if necessary. I would also replace the relays.
Afterward, check all solder joints and re-solder if necessary.
It's definitely worth it.

 

[olds1959special]

The amp shop said the power supply was okay, but there was something wrong with the pre-amp section. The cost to fix is more than what I paid for the amp, but I asked them to proceed with the repair because I don't really have a better option.

 

[olds1959special]

The amp is fixed. The problem was from cracked solder causing grounding issues. No more buzzing and I love the sound of these amps!

 

[Roland68]

The amp is fixed. The problem was from cracked solder causing grounding issues. No more buzzing and I love the sound of these amps!View attachment 461156

I'm happy for you. It's great that your wonderful treasures are working again.

Your system shows well that you can have a great system with current devices and devices that are up to 40 years old. The Vandersteens were also way ahead of their time, and it probably won't be easy or cheap to replace them with newer speakers.

 

[Sal1950]

The amp is fixed. The problem was from cracked solder causing grounding issues. No more buzzing and I love the sound of these amps!

I'm really happy for you, I know the warm feeling of using an old friend amp.
I'm using 5 30+ yo Adcoms in my 5.2.4 rig that I should have upgraded years ago but ------------