Not working for me - I can't hear anything. :scratch:
Printable View
Not working for me - I can't hear anything. :scratch:
Short version has it at 2, 4, 8 and 12 seconds.
I'm just hearing his not hum, must be below the FR of my laptop speakers.
i heard it on my lappy. its not loud and shot burst. could be a lot of stuff i guess from dodgy cap to something coming in on mains..
It is not present when the AG1500 is connected, so it is mains based.
So, is fitting an isolation transformer before the transformer in the phono stage a crazy idea?
Use the 1500. If it's like mine it can sit on its side tucked away at back or side .my display turned to vertical mode too.
That is what I am currently doing, but I would like something more aesthetically pleasing.
I have played with Audacity this morning.
I have reduced the hiss, and performed a spectrum analysis of the sound clip.
As I thought, this is a 50Hz noise and it's harmonic. So it would seem that the only option to remove it is a mains regenerator?
Or would an isolation transformer work in this situation?
Here is the plot:
https://drive.google.com/file/d/1Bus...ew?usp=sharing
If it was me I'd just get another phono stage and have done with it. You're talking thousands for a proper power regenerator.
Who would want to buy a 2nd hand "noisy" phono stage?
I would need to sell it to help fund a new purchase.
In the short term, I can fit another phono stage, if I wanted to.
I have 5 MM stages and 3 MC stages "available", but they are not mine.
Have you tried a different phono stage?
I'm assuming you have and if it removed the noise and it was me I'd be putting a different one into play especially if it was bugging me.
Yes. No problems with the other phono stages. The Reflex M and Accession M both work fine, but I have to keep shipping them out when people want to borrow them. ;)
The AG1500 removes the problem on the BB3, so I have noisy mains that the BB3 is susceptible to.
Ideally I want a simple solution to get rid of that noise, that I can fit inside the case.
If I can't do that, I will keep the AG1500 in place.
I'm not convinced about the noisy mains thing, everyone's mains is noisy. If it was a real problem hi-fi wouldn't exist.
Is it not more likely it's some sort of ground loop? Using the AG1500 might be fixing that?
Now I know it is most likely to be a 100Hz interference signal, I am also thinking it is a ground loop issue.
But why is it just the analogue part of the system affected?
ground loops can be buggers especially if the set-up is complex i.e lots of boxes.
The BB3 will probably be fine in a different system.
I am going to swap my pre out, and see if it is a mixture of SE and Balanced connections.
But thinking about the last statement, the noise was present when the BB3 was the only thing connected to the mains, and the audio clip was done. It fed the PC sound card directly, so a change of Pre is not going to help.
The PC was connected to the mains though? And the phono stage was connected to the PC?
Load of ground loop threads here https://www.audiosciencereview.com/f...=ground+loop&c[title_only]=1&o=relevance
You might find a solution there - or at least more things you can try.
I have just altered the grounding “scheme” of my BB3, and the hum has reduced significantly.
It is not 100% gone, but I am almost there.
I do have to point out that it is with the volume cranked right up at levels I do not normally use, with no music playing.
I am almost at a point now where the hum is acceptable.
Is this more to do with the fact you know it's there rather than the impact on the music then? I'd try and live with it for now and you might forget about it.Quote:
Originally Posted by CageyH
Totally.Quote:
Originally Posted by Lawrence001
I don’t believe there is much impact on the music, but I want to minimise stray signals in the phono stage.
I think I have actually nailed it.
It has taken long enough….
In the end, what caused the hum?
Rather enigmatic [emoji23]Quote:
Originally Posted by CageyH
Either the fridge/freezer (Samsung “digital compressor”) or the Fridge, or the Freezer.Quote:
Originally Posted by Barry
Ferrite beads fitted on all three and the level and occurrences of the hum has dramatically decreased.
At normal listening levels, I can no longer hear it. If I wind the wick right up, you can just about make it out.
Actually, I give up on tracking down the cause.
It is back with a vengeance….
The AG1500 is going in, and staying in for the foreseeable future.
And my AG1500 is showing me that the AC is varying wildly from 221 V to 232 V as I watch the input voltage.
You got some massive power user near you. One of my mates monitors his electrical supply voltage and it sure takes a dip when his next door neighbour switches on his electric furnace!:eek:
We have a couple in the area.
Cereal collection points, where I believe they also dry the grain.
Either that or the AG1500 is playing up.
I know you're convinced it's Mains borne, but.............
Is it a constant Hum/Buzz or intermittent. You have mentioned (and the title of the thread is ''Occasional.....'')
Could it be an Internet Router?
Cordless 'phone and Base station? They send int't signals out to one another to check they're still 'there'.
Mobile 'phone? These int'tly send/receive short bursts of info.
All the above can be picked up by Phono Stages, especially Valve ones.
Try unplugging everything for a night or two, you'll like going off-grid !!!!
Then plug things back in one by one until the culprit is found.
Just a suggestion, all worth a go.
J.
Thanks Jim.
It is a 100Hz and 200Hz noise, so for me, it is mains based.
I don’t use a fixed phone anymore, so the base stations have been unplugged a long time ago.
The internet router has been turned off, and it made no difference.
I tried all of this when the family was out, and also turned off the mobile phones.
The noise was still there.
It is intermittent, and low level. My money is it being my air source heat pump, so I need a way of filtering this noise.
I have been reading up about this, and it seems that this is due to the full inverter in my heart pump, injecting harmonics back into my mains, and it is suggested that a line reactor may fix it.
I thought lune reactors were a three phase thing? Any thoughts on this?
I assume "heart pump" is a misspelling of heat pump.
A mains conditioner will be of little help as they have to pass the mains components of up to a few hundred Hz to allow rapid transient switch-on rise times.
It would seem that your heat pump uses a variable speed motor (VSD) and use an inverter, which as you have found out will cause switching spikes at harmonics of the nominal mains frequency. I think you will need to consult a qualified electrician for advice, as anything designed for audio use will be inadequate.
Heart pump is indeed an autocorrect.
I am looking at solving the issue, rather than curing the effect, so I think you are correct. A qualified electrician will be required
I recently addded a common mode noise filter to the BB3, as I had a PCB gathering dust.
It is now silent, but the heat pump only heats the hot water now, so is not on for so many hours a day.
The original case is now pretty full, so I am going to rehouse the BB3 in a bigger case that will give me better separation between components in there.
https://www.diyaudio.com/community/t...-noise.412589/
An interesting article.
Agreed - but nothing in it that should come as a surprise. It also 'criticises' Shaffner filters which is unfair if they are being used outside their specification.Quote:
Originally Posted by CageyH
Regarding Schaffner's CM and DM performance figures as a function of frequency, being only measured for terminating impedances of 50 Ohm, however if you delve further you can find similar measurements for a source impedance of 0 Ohm and an open circuit load. The IEC assumes the mains source impedance is 0.4 + j0.25 Ohm (IEC 725:1981).
The author hints that at high frequencies (that is above 50Hz) the mains distribution system ought to be treated as an RF transmission line. Well asuuming the dielectric insulation is PVC (Dielectric constant = 3.2) then the wavelength/2*pi at 20KHz is 33km, so assuming the distance to the nearest substation is no more than 1km, then this is 0.03 of a guide wavelenth/2*pi, so transmission line theory does not apply.
But the author is correct in that filters should not be cascaded - they will interact, and quite often with reduced overall performance.
I have an Olsen 6-way distribution strip that is fitted with a Schaffner 15A filter, which I used with my audio system without any problem.
The new case arrived today.
Attachment 31416
It is bigger than the last one, as I am going for greater separation between the power and phono PCB this time around.
It is a full width case, and a little deeper than the one I used originally. This should make the build easier, and hopefully neater.
Progress:
Attachment 31417
Power switch and RCA socket holes drilled out by hand.
New case layout options:
https://ibb.co/BG1tkqV
https://i.ibb.co/MfXsdMD/PXL-20240729-201828414.jpg
Or
https://ibb.co/CvXD0Kt
https://i.ibb.co/MfXsdMD/PXL-20240729-201828414.jpg
Which do you think will be best?
I have gone for a variation of the 2nd layout to keep the mains cabling relatively simple, and (hopefully) tidy.
I just need to think about the best way to extend the transformer secondary cables now.
Should be back up and running by the weekend.
Definitely option 2. The first one looks a right old mess.
I can't see any difference between the two layouts.
.
I had problems with the images not showing.
Option 2 makes the mains cabling easier/tidier.
I am just waiting for some parts before I can finish the cabling and fire it back up.
Hopefully the common mode filter will make a difference to my problem, that and further separation from the mains should mean less interference.
Me neither. Just a lucky guess :DQuote:
Originally Posted by Barry
:lol:Quote:
Originally Posted by Pigmy Pony
It looks tidy without the mains cabling.
Jobs a good'un.
https://ibb.co/y5nQrpJ
No hum has been heard, yet.
I could also swear that it sounds better than it did before, but that may just be my bad aural memory.
The hum came back shortly after my post above.
I then started to check my mains and saw that there was an issue in the quality of the mains. After months of not using my BB3, I turned it on again today, for the first time in a long time.
The difference now is that the mains cable feeding the village has been replaced/upgraded.
This caused more problems, as the local transformer could not handle the increased power delivery.
Fast forward until a couple of months ago. A new transformer was installed, and we had a date in February where the connection was going to be made.
Well, that didn’t happen. Until today. A forecast 4 hour power cut, that lasted 5 hours.
I waited a while before I powered up the BB3, and finally when I did, there is not the slightest hint of occasional hum.
So basically this thread can be summarised by “Poor power supply causes phono stage hum and there is very little that can be done about it”.
At least (I hope) I am not far from a happy ending….
Hooray, I like happy endings.