Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 15,975
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Post by Bigman80 on Jan 5, 2021 12:09:39 GMT
Thats mechanical hum/buzzing...as in the laminations of the Transformer vibrating. I experienced that many times and a DC blocker will not cure it. It may reduce it slightly but ime it is not a cure. A DC blocker must also have enough capacitance to store the DC. That aspect is often overlooked. The only cure is to use well made transformers, and that was something i highlighted many years ago when i had an NVA Phonostage 2 (Shock-Horror ) It had 2 power supplies and both buzzed like a bee hive. Thankfully now, The new owner of NVA uses transformers from Toroidy, so this issue shouldn't affect their product line anymore. My own BMU buzzes a little as i got my transformer from Airlink, who i havent used since. If the buzz comes and goes then it is DC on the mains. Some DC blockers are more effective than others, but the ones I've tried have all sat on the sound, so I prefer to tuck the BMU away behind a sofa or in a cupboard and do without the DC blocker. YMMV Airlink transformers are very good...but we have found that Toroidy are better, and lower cost (if bought in quantity). Paul?? Is that you??! lol, welcome back (briefly?) Yes, Toroidy are better. Not in question.
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Post by misterc on Jan 5, 2021 12:51:10 GMT
The issues are simple with Balanced units, the right TX FULLY ISOLATED and suspended and a correctly designed dc blocker, not a pair of FBR and some 20Kuf caps on some glorified breadboard Oh a nice enclosure is necessary as well. Not all BMU are the same, BUT do remember if you did it properly you would probably whine at the cost
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Post by misterc on Jan 5, 2021 13:13:55 GMT
Regarding the utility of the graph as requested by MrC, it's interesting. I assume the big spike at 50hz is the only one that is supposed to be there and is the 50hz frequency of the UK mains supply. All the other spikes are noise and are a Bad Thing? The point of the graph seems to be a comparison between unfiltered mains and the effect of a device called the Harvester aimed at reducing noise. Red line compared to blue line. It seems to have very little effect. I'd be interested in similar graphs showing the impact of other noise reducing tech. Also interesting would be subjective assessments of the impact, if any, on sound quality of hifi gear being powered by each noise reduction tech. Hi Jerry The spike on that graph is actually 60Hz as asr is US based hence my gib Ideally for the lay person to a base line graph would be helpful before making any comparisons so when you do view a graph you will be able to instantly grasp the differences. S/N in that case is no relevant, they are standards set in law CE CISPER regulations that have to be adhered to. Depending on the product as to which standard are applicable. Those noise figures EVEN before the mains device was fitted would fail a CE test here at certain points on the graph. In the UK with 50Hz being the fundamental (First harmonic point) generally the 'odd' harmonics are measured on the mains upto around 50th harmonic 2.5Khz but the last say 15 or so would be as we term do in the mud! (such a low level as to make no difference say -80dbc and below). However the regs have several measurement areas such as 9Khz - 30Mhz and up to 100Mhz so you would be surprised at the crap that sits up there even with 90dB PSRR! Because the noise is not in the audible band doesn't mean it doesn't effect it in some ways!
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Deleted
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Post by Deleted on Jan 5, 2021 13:28:18 GMT
Mention NVA and Savvy pops up.... đź‘‹ I look forward to seeing his other contributions on this forum.
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Post by savvypaul on Jan 5, 2021 13:51:36 GMT
Mention NVA and Savvy pops up.... đź‘‹ I look forward to seeing his other contributions on this forum. I answered a very specific issue. About BMUs, not specifically NVA. I've no plans to stick around. BTW, you have unread messages at HFS. (Admin, please remove this last sentence if it breaks any forum rules, here).
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Deleted
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Post by Deleted on Jan 5, 2021 13:52:49 GMT
Thanks for letting me know. đź‘Ť
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Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 15,975
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Post by Bigman80 on Jan 5, 2021 16:13:56 GMT
Mention NVA and Savvy pops up.... đź‘‹ I look forward to seeing his other contributions on this forum. I answered a very specific issue. About BMUs, not specifically NVA. I've no plans to stick around. BTW, you have unread messages at HFS. (Admin, please remove this last sentence if it breaks any forum rules, here). Shame that. Always enjoyed your posts, Paul. ATB.
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Deleted
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Post by Deleted on Jan 5, 2021 21:14:19 GMT
Found the buzzing noise. It’s my AG1500.
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Post by macca on Jan 6, 2021 9:00:22 GMT
cure is worse than the disease - whatever the disease is supposed to be which I still haven't figured out.
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Deleted
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Post by Deleted on Jan 6, 2021 9:22:52 GMT
It never used to buzz. The issue I had was DC on the mains, that caused the traffos to buzz loudly.
There are some large grain drying/storage plants in the village. It may come from these.
I figure that a balanced mains unit or an isolating transformer maybget rid of this effectively.
I have contacted Pkwer Ispired to see what they say about the buzz.
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Post by sq225917 on Jan 6, 2021 11:38:55 GMT
Probably asymmetric waveform
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Deleted
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Post by Deleted on Jan 7, 2021 10:29:01 GMT
Probably asymmetric waveform Power Inspired have suggested that it may be dust causing vibrations, and I should carefully clean the inside, and report back if there are remaining issues.
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Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 15,975
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Post by Bigman80 on Jan 7, 2021 12:41:06 GMT
Probably asymmetric waveform Power Inspired have suggested that it may be dust causing vibrations, and I should carefully clean the inside, and report back if there are remaining issues. That's interesting........ Noisy dust.....!
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Deleted
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Post by Deleted on Jan 7, 2021 13:09:56 GMT
I guess it depends on where, and how much dust there is. I will find out at the weekend.
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Post by sq225917 on Jan 7, 2021 13:29:53 GMT
Noisy dust, cough, cough, bollocks.
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Deleted
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Post by Deleted on Jan 7, 2021 17:38:59 GMT
Yeah, but it is “Super Magic Dust”.
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Post by macca on Jan 7, 2021 19:51:06 GMT
Put some Dusty Springfield on, that'll sort it.
Or The Dust Brothers.
Alvin Stardust? Must be good with dust, name like that.
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Deleted
Deleted Member
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Post by Deleted on Jan 7, 2021 19:58:27 GMT
Every day I get in the queue (Too much, Magic Dust)
To get on the duss that takes me to you (Too much, Magic Dust)
I'm so nervous, I just sit and smile (Too much, Magic Dust)
You house is only another mile (Too much, Magic Dust)
Thank you, driver, for getting me here (Too much, Magic Dust)
You'll be an inspector, have no fear (Too much, Magic Dust)
I don't want to cause no fuss (Too much, Magic Dust)
But can I buy your Magic Dust? (Too much, Magic Dust)
Nooooooooo!
I don't care how much I pay (Too much, Magic Dust)
I wanna drive my Dust to my baby each day (Too much, Magic Dust)
I want it, I want it, I want it, I want it ... (You can't have it!)
Thruppence and sixpence every day
Just to drive to my baby
Thruppence and sixpence each day
'Cause I drive my baby every way
Magic Dust, Magic Dust, Magic Dust ...
I said, now I've got my Magic Dust (Too much, Magic Dust)
I said, now I've got my Magic Dust (Too much, Magic Dust)
I drive my baby every way (Too much, Magic Dust)
Each time I go a different way (Too much, Magic Dust)
I want it, I want it, I want it, I want it ...
Every day you'll see the dust (Too much, Magic Dust)
As I drive my baby in my Magic Dust (Too much, Magic Dust)
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Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 15,975
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Post by Bigman80 on Jan 8, 2021 21:14:14 GMT
Every day I get in the queue (Too much, Magic Dust) To get on the duss that takes me to you (Too much, Magic Dust) I'm so nervous, I just sit and smile (Too much, Magic Dust) You house is only another mile (Too much, Magic Dust) Thank you, driver, for getting me here (Too much, Magic Dust) You'll be an inspector, have no fear (Too much, Magic Dust) I don't want to cause no fuss (Too much, Magic Dust) But can I buy your Magic Dust? (Too much, Magic Dust) Nooooooooo! I don't care how much I pay (Too much, Magic Dust) I wanna drive my Dust to my baby each day (Too much, Magic Dust) I want it, I want it, I want it, I want it ... (You can't have it!) Thruppence and sixpence every day Just to drive to my baby Thruppence and sixpence each day 'Cause I drive my baby every way Magic Dust, Magic Dust, Magic Dust ... I said, now I've got my Magic Dust (Too much, Magic Dust) I said, now I've got my Magic Dust (Too much, Magic Dust) I drive my baby every way (Too much, Magic Dust) Each time I go a different way (Too much, Magic Dust) I want it, I want it, I want it, I want it ... Every day you'll see the dust (Too much, Magic Dust) As I drive my baby in my Magic Dust (Too much, Magic Dust) Hahahaha! Brilliant....I sang it as I raid it lol
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Deleted
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Post by Deleted on Jan 9, 2021 15:27:47 GMT
The magic dust, and a flexible plastic cover have ben removed. The noise is still there, so I guess it is a vibration from one of the many coils, or the small transformer that is causing the noise. It's a shame, because I was going to collect the magic dust, and sell it on eBay. It could possibly have fixed broken speakers etc. Now that the dusting has been done, I guess I now have clean power again.
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Bigman80
Grandmaster
AA Founding Member & Bigbottle Audio Creator
Posts: 15,975
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Post by Bigman80 on Jan 9, 2021 15:48:43 GMT
The magic dust, and a flexible plastic cover have ben removed. The noise is still there, so I guess it is a vibration from one of the many coils, or the small transformer that is causing the noise. It's a shame, because I was going to collect the magic dust, and sell it on eBay. It could possibly have fixed broken speakers etc. Now that the dusting has been done, I guess I now have clean power again. I'm surprised removing the dust didnt work .........
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Deleted
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Post by Deleted on Jan 9, 2021 17:41:23 GMT
I have removed the AG1500. No transformers are humming. I will,see what P.I. Have to say next week.
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Post by misterc on Jan 13, 2021 17:15:10 GMT
I had some time today to take some mains measurements at home:
This meas is taken at the IEC before any EMI filters and so harmonic content up to 2Khz I was using the Class 'A' set of standards for consumer home audio and other consumer goods. Current draw primary on the ac side for this device is 0.95 amps at 240vac and 50Hz
I would like to point out it the reading was taken with the device going through a off the shelf strip filter block.
Scale on the bottom graph is 400ma per vertical division.
You can the limits and actually measurement in the bottom left hand table all reading made with 1.25million samples per second.
This is actually not to bad but before any inside filtering the equipment may preform.
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