I envy you. Not many things out there that are as satisfying as rebuilding one’s setup. Good luck and may the sound be with you
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What a nice post. Thank you.
Hope you have resolved your hum problem. I know that it would drive me crazy
New rectifier received on Tuesday. FedEx delivered it outside of their 4 hour delivery window by an hour; dropped it over a side gate in the rain and then claimed it had been both “delivered” and signed for by me. At the time I was stood on platform 3 at Manchester Victoria about to get a train to Chester.
On opening the rectifier looks fine. I am unable to test it as yet because I noted a small tinkling sound just as I was about to remove the Brimar and put the Svetlana in. Tapped the left side of the amp very very gently and there it was again. Tapped the right side and… nothing.
Guessed it was the left PSVANE CV181-TLL. Removed it but there was no tinkling. Removed the left 300B and there it is. Damn.
So, further request to Poland for either a data sheet matched 300B or a matched pair. Somewhat frustrating. Obviously can’t risk using the amp in the meantime.
Prior to this I finally measured the hum. 50/60hz. Seem to be lots of contradictory internet views on what that tells me 
Which?
All along I have assumed 50Hz mains hum. But if 60Hz it can’t be, pointing to a different cause.
Not according to some very different people I’ve spoken to so far. That would be the manufacturer of the amp. A manufacturer of other amps. Friend who has built their own DACs. Our electrician (sadly not available to come see at present) and an other electrician who does contract stuff for a dealer in the NW of England. Consensus view of all is that both would suggest mains.
So is it 50 or 60? Any frequency measuring device should b able to telll you, not 50/60, I would expect mains, 50, but as I said, if 60Hz and in UK as you are, it cannot be mains! (If whatever you are using to measure is that poor that it cannot differentiate, I suggest download other apps, even a frequency generator to play a tone for you to assess by ear! )
I used a frequency generator. I cannot be more precise. I would say 50.
If 50 then yes, mains hum as anticipated.
Out of interest, if it were 60?
Other than not arising from the mains I have no idea at all how a hum at 60Hz could arise in an amp, but to the manufacturer it would likely point to something very specific, whereas mains hum could be either ripple from the power supply or electromagnetically induced, and the latter not necessarily from within the amp.
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Ta.
Have to say the manufacturer has been fantastic. Could not have been more impressed.
Replacement and matched 300B received yesterday so immediately put the replacement Svetlana rectifier in and attempted to put the 300B in the left socket. Absolutely didn’t want to go in and came up short of flush by about 2mm. Tried it in the right socket and it was even worse. Was then seriously concerned I couldn’t get it out of the right socket without breaking it. Eventually got it both out and into the left socket.
Dreading the removal when I go buy some WE 300Bs but the big takeaway on switch on was just how much difference there is between a £35 Brimar and a £30 Svetlana. Amp absolutely sang from the off with zero hours on both the rectifier and the left 300B compared to 47 hours on the Brimar and 170 on the other 300B. No problem launching into an evening of 7 hours of music at all.
Inevitably the very low speaker hum remains. What I can’t get my head around is that when I switched the amp back to standby, so that everything is off bar one light on the front panel saying 300B, the amp was silent. Over an hour later there is a very buzz from the body of the amp (not the transformers, I think). Again, it’s very low. Ear next to the amp to detect anything but… what on earth could that be?
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IFi DC blocker installed but had to also acquire a small length of cable to assist as hanging out of the amp it’s too heavy and would pull the IEC out. Bottom line is that the DC blocker did not work and will need to be returned so we’re down to:
- efficient speakers.
- doesn’t like >230V.
- amp is somehow faulty.
Noted that after adding the replacement rectifier and 300B the little whizzy sound I got on boot up is back. Not concerning as yet but a listening ear is paying attention. Maybe it’s just what the Svetlana rectifier does but maybe not?
iFI also do a Ground Defender which is used for speaker hum, so could be worth trying.
DG…
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Noted. Thanks.
What the heck.
Powered down the amp after 8 hours of podcasts, music and TV. Accidentally started a podcast via Innuos Sense app and thought I could hear it playing tinnily somewhere in the vicinity of the hi-fi. I could. Sound very clearly coming out of the Chord Hugo TT2 DAC. Amp totally off. No headphone inserted in the latter for at least 3 years so, er, a ghost in the machine?
All suggestions welcome on this one.
Just a guess here, but the DAC is stuffing enough energy into the amp (even though it is off) to move the tweeter.
Try disconnecting the amp input and see if it is still happening?
The sound was not coming from either speaker. The sound was coming from the DAC. Can’t quite believe it myself but there we are.
Hi Mike,
These things are super frustrating. I have been stressing my brain to think of possibilities. I have had comparable experiences sometimes when trying to undertake some of the more complex microphone measurements on my system. The thing is, with high frequency content only and at a low level, it can be quite difficult to discern the precise source.
In my case I have variously had the preamp punching through sound to the loudspeaker with the power amp off (my original suggestion for you). The streaming source (MacMini or iPad mini) playing through its own speakers, even though I was certain I had made the correct output selection to go to the main preamp. The temporary screen I attach to the computer (when doing REW measurements in Music Mode for my room) outputting sound from its weedy speakers, again when I was certain the output was going to the preamp.
So, my only suggestion is to really make sure you think the sound is sourced from the DAC, perhaps by getting another person involved in the assessment at the same time to cross check their perceptions of sound source from other possible items.
Good luck - I am definitely interested in how you get on.