Either all my amps have problems or .... ??

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Generators put out REALLY ugly power, so that may tell you nothing.
To prove it is amp forward, just disconnect everything and short the inputs to the amp. Troubleshoot with as little in the system as possible. The mains issue may not even be in your house.

Remember the service agreement from the utility is power to run incandescent bulbs and inductive motors. If you do anything else, it is your problem. Unfortunately, manufactures, even big buck smart ones, make way too many assumptions about the power. If I am paying more than big-box store prices, I expect it to have whatever is need. So,see ESP for the fix, and yell at Threshold! A big honking isolation transformer will fix you right up!
 
Thanks to all and Hi to all !!

Seems your stuff all blows up at the merest whiff of lightning storms.

Honestly system7 I've never had such problems until we moved out here into the wilderness. Lived in many a major city in different countries and some not so major and never had the d***** problems that I have had here. Pappa's designs are IMHO some of the best but I'm doubting if any system can stay the course out here. Brownouts, blackouts, net-outs, phone-outs, you name it outs. Oh and the cables were done from a DIYaudio post - no bellwire honestly :)

Hi KandDad:
In a normal domestic installation, all the sockets are in parallel. At least they are here in the UK.

Not in this cottage - they tied a rope attached to the wire for the ring mains installation around a rat's neck and then yelled GO !! And it went alright - every which way it could. As I've posted before I've spent hours trying to suss out the wiring here - it was added on to gradually over the centuries to become the nest that it is now. I know the answer of course, all it needs is a time-served electrician and 25K do-it Shekels and we're good to go, but me no got 25K dimes that are loose/handy/available :((((

As Andrew and others have said (thank you all) go the DC blocker route (and if I can try a 120 genny first) but it's still a complete mystery to me as to why I hear it now. I have not had my head in the sand for the last few months (honestly) and would have noticed a somewhat suppressed 'machine gun' in the room. And then there's that HF oscillation possibility - but same cables etc etc etc. Baffled and off for a short kip - been at this all night. Thanks again guys, see you later. Mike.

DF96: so right (as tvr agrees) - and I will try doing exactly that also.
 
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I personally have no problem with DC on mains in UK.

Is this unusual to the US ?

My Pass Aleph 4 hums slightly, I put that down to the sheer load on the transformers. (Over 800W).

That is mechanical transformer hum not audible supply hum.

It's quieter than the fish tank so I ignore it.
 
Thanks to all and Hi to all !!



Honestly system7 I've never had such problems until we moved out here into the wilderness. Lived in many a major city in different countries and some not so major and never had the d***** problems that I have had here. Pappa's designs are IMHO some of the best but I'm doubting if any system can stay the course out here. Brownouts, blackouts, net-outs, phone-outs, you name it outs. Oh and the cables were done from a DIYaudio post - no bellwire honestly :)

Hi KandDad:

Not in this cottage - they tied a rope attached to the wire for the ring mains installation around a rat's neck and then yelled GO !! And it went alright - every which way it could. As I've posted before I've spent hours trying to suss out the wiring here - it was added on to gradually over the centuries to become the nest that it is now. I know the answer of course, all it needs is a time-served electrician and 25K do-it Shekels and we're good to go, but me no got 25K dimes that are loose/handy/available :((((

As Andrew and others have said (thank you all) go the DC blocker route (and if I can try a 120 genny first) but it's still a complete mystery to me as to why I hear it now. I have not had my head in the sand for the last few months (honestly) and would have noticed a somewhat suppressed 'machine gun' in the room. And then there's that HF oscillation possibility - but same cables etc etc etc. Baffled and off for a short kip - been at this all night. Thanks again guys, see you later. Mike.


Are you telling me that your domestic installation has a 3 Phase supply ?

In UK the Power Station feeds a 3 Phase supply to a substation. At the substation it is transformed down from 33000V to about 440V 3 Phase.

We then use a single phase of the 400 which is 240V and good for about 40 houses.

A street of 100 houses would share the output of a single substation.

I appreciate thet in the US you use local transformers at the top of poles, but I find it strange that each house would have a three phase feed.

Maybe I'm wrong. We do use use 240V to reduce the current. You use 110V cos its apparently safer.
 
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3 phase feed into houses is not uncommon in the US. I had a plug wired for 220V so I could run an electric kettle.

DC is a problem in the UK. However, since the US is at 110VAC, the primary is likely to have a lower DC resistance so I would expect that the issue is slightly worse compared to the UK and the rest of EU.

I also think UK/EU regulations regarding AC loads are probably stricter. You would not normally notice this, because its the manufacturers who would come up against this during product qualification.
 
DC on the mains is caused by someone nearby taking a DC current from the mains (e.g. by directly connected half-wave rectification). That DC current has to come from somewhere. If you are on the end of a local feeder then it could be your toroidal transformer. If you are near the step-down transformer then it will take the DC instead as it will have a lower DC resistance than any domestic item.

In the UK each phase is fed to roughly every third house, so DC is unlikely to be caused by your immediate neighbours but 3, 6, etc. doors away in either direction.
 
Hi KandDad: no, not three phase just a single messup phase system. I'll take the British 3 pin plug and socket anytime over the 'weeny' US mains plug/socket version - and I'd be very happy with 240V mains. Why choose 120V - for safety reasons - I don't think so. Most probably something to do with cost as it always does :( I reckon squirrels have a great feed feed from pole-top transformers - and they're really ugly sods too - the transformers - not the squirrels !!

I'll connect up again when I get up and post the results. Thanks again, Mike.

That BIG isolation transformer sounds good too !!!
 
DF96:
DC on the mains is caused by someone nearby taking a DC current from the mains (e.g. by directly connected half-wave rectification). That DC current has to come from somewhere. If you are on the end of a local feeder then it could be your toroidal transformer. If you are near the step-down transformer then it will take the DC instead as it will have a lower DC resistance than any domestic item.

Nail on the head - there are only 5 more 'houses' after ours to the end of this particular feed so I'm told. Then again I wouldn't particularly be too keen to believe anything that the 'local authorities' say - they might have some kind of topo map - but I sincerely doubt it.
 
DC on the mains is caused by someone nearby taking a DC current from the mains (e.g. by directly connected half-wave rectification). That DC current has to come from somewhere. If you are on the end of a local feeder then it could be your toroidal transformer. If you are near the step-down transformer then it will take the DC instead as it will have a lower DC resistance than any domestic item.

In the UK each phase is fed to roughly every third house, so DC is unlikely to be caused by your immediate neighbours but 3, 6, etc. doors away in either direction.

HaHa, I KNEW DF96 was a mains electricity expert. Very informative on DC interference, that. That's why he and I never agree about cable impedance. I always calculate it at Radio Frequencies, he does it at 50 Hz! Sorry, off-topic, but DF96 will laugh! :D
 
3 phase is almost only in commercial space, 208 or 480V. Residential is 2 phase , 220 which is broken out as both 2 phase 220 in the house and two branches of single phase 110. We have this system because it was what Mr. Westinghouse said.
Do not confuse two phase 220 with earth as three phase. Three phase is separated by 120 degrees, two phase by 180. It requires delta or Y transformers.
 
DF96:
A proper DC blocker will solve the problem, not mask it, at least for the items downstream from the DC blocker. The alternative is to find all the neighbours taking DC (which could be most of them, with modern SMPS in almost everything) and buy them equipment with proper mains transformers.

Many thanks for the very clear statement on the DC blocker. I will have to go that route. The noise is there with inputs shorted etc..

As always I owe you diyaudio guys a GREAT BIG thank you for all your time and effort to help me.

Mike.
 
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