DIY BMU build

[Bigman80]

Here it is. All built but need to swap the 10a MCB for 6a MCBs

It has removed the intermittent powerline adapter noise. Only problem is, I have a buzzing sound now. [emoji31]

Any suggestions?https://uploads.tapatalk-cdn.com/20180125/deec7eeea048818e3ccad022536183c4.jpghttps://uploads.tapatalk-cdn.com/20180125/f7847f386e4aa3e24c18271d918d592b.jpghttps://uploads.tapatalk-cdn.com/20180125/323b37de76bf0a6e01c8391ae0a2e06c.jpghttps://uploads.tapatalk-cdn.com/20180125/da0ecbecccf89df430904b3e99b21cd2.jpg

[Barry]

Looking good Oliver,

But the MCBOs need to be ganged, so that if one trips out due to a fault condition, both live (115V) conductors are disconnected. Ideally you should use a 2-pole ganged RCBO.

[Bigman80]

Looking good Oliver,

But the MCBOs need to be ganged, so that if one trips out due to a fault condition, both live (115V) conductors are disconnected. Ideally you should use a 2-pole ganged RCBO.They are connected by a metal pin, Barry. Of one trips, they both trip. Tried and tested.

[Barry]

They are connected by a metal pin, Barry. Of one trips, they both trip. Tried and tested.

Ah - I couldn't see that from the photo. It would be better still if a two-pole residual current circuit breaker was used, to provide protection against asymmetrical current leakage.

[Gazjam]

The buzzing probably means you have DC on your mains.
Get a DC blocker in there Oliver, either in the chassis if you have room or an external box between the mains feed on the wall and BMU.

Fitted one to my Airlink unit recently, buzzing is gone.


THe BMU, whats your perception of sound quality changes?

[Bigman80]

The buzzing probably means you have DC on your mains.
Get a DC blocker in there Oliver, either in the chassis if you have room or an external box between the mains feed on the wall and BMU.

Fitted one to my Airlink unit recently, buzzing is gone.


THe BMU, whats your perception of sound quality changes?There is a DC blocker in there, it does reduce mechanical hum.

Well, it seems the BMU is not having the desired effect. I am getting more hum now than previously. I have stripped everything out and put in place a multi plug which I built. Very simple, just wired with standard flex and switchless sockets and stared plugging things in one after the other.

I have some hum on the Phonostage which I hadn't realised but the Rothwell SUT is adding to that. The IC cables I use aren't shielded so that needs addressing. But it's 90% quieter without the BMU. Looks like it'll be for sale. [emoji21]

Barry,

I agree but it was just put together with bits I had to see if it would be beneficial and it's not, in my house anyway.

So the BMU is out, DIY multiplication is in.

[Gazjam]

Mines is hardwired and my mains is shit...may be a factor.

[Bigman80]

Right, I take it back

I've taken the SUT out and the phonostage and put the Vivant in with direct MC connection.

Volume on full and the mains sounded horrific but NO hum. Dropped the BMU back in volume on full and voila, almost silent.

So diagnosis is - Wizard phonostage needs a bit of help to dispel the hum and the SUT needs some position help.

Sound with the BMU in is clean. Almost added a bit of depth and dimension. https://uploads.tapatalk-cdn.com/20180125/5f63766d5f20d8279a55e1df935de1c5.jpghttps://uploads.tapatalk-cdn.com/20180125/8f1ac264c8a10fcfc617c3da79c1394d.jpg

[Firebottle]

:yay: Way to go ....

We'll try some fixes with the Wizard to see where it is lacking, could be that a resistive link to the chassis may be beneficial.

[Bigman80]

Right, Rothwell SUT back in with the Vivant and......... No hum, hiss or nasty sounds. SO.....it's the bloody Wizard phonostage.

[Yomanze]

Right, Rothwell SUT back in with the Vivant and......... No hum, hiss or nasty sounds. SO.....it's the bloody Wizard phonostage.

Interesting, maybe the Wizard just doesn’t want to see -120V on neutral. This has often been cited as a potential issue with balanced mains.

[Jimbo]

At least your efforts were not in vain!:) But now you have to do more work on the Wizard!:doh:

[Bigman80]

Interesting, maybe the Wizard just doesn’t want to see -120V on neutral. This has often been cited as a potential issue with balanced mains.That's a good point but it wasn't as quiet as the Vivant previously so I think there is definitely a bit of work to do.

[Bigman80]

At least your efforts were not in vain!:) But now you have to do more work on the Wizard!:doh:Yes, Jimbo. Bittersweet but not too much of a worry. Alan has a couple of ideas. Apparently the Vivant is grounded in a different way to the Wizard so we may have an easy fix.

[Bigman80]

Last update as I have now exhausted all the combinations I can think of.

The Wizard makes no change to hum level when plugged in via the BMU or directly into the wall socket.

The SUT is more prone to hum when connected to the Wizard so my conclusion is that the Transformer in the Wizard is omitting a massive amount of interference.

I have the SUT next to the Vivant without any issue bit it's almost a meter away from the Wizard before I reduce the hum to similar levels.

Due to this, I may put the PSU into a separate box and use a long umbilical to the Phonostage.

Welcome to other suggestions!

[Bigman80]

Quick update,

I've had the BMU up against a Tacima 6 way power conditioner today.

The Tacima would've solved my noisy mains problem for £30 and had I known about it earlier I probably would've never built the BMU. it's a cracking bit of kit but there is a compromise, in my system, the soundstage narrowed a touch and the HF didn't stay as natural.

The BMU seems to have little in the way of compromise other than the mechanical buzzing of the toroidal TF. Which is pissing me right off 🤣

A better quality TF will obviously fix this but it'll have to wait.

The BMU is a big winner here, I love it. Shame it's buzzing but I'm now a mains quality convert. It's well worth getting one if you're just plugging in to the ring main directly like I was.

Thanks to Shaman for convincing me with tales of his *** BMU. A much welcome addition to my system.

Thanks to Alan for donating the BT unit and your continued assistance [emoji6]

[Blueflash]

Some of the hum will be the case resonating with the transformer. Start with getting some 10mm thick neoprene foam and put it on the top and bottom of the transformer. That will help de couple the transformer mechanically from the case.

Then get some "Dead mat" sound deadening sheets and stick it to the inside of the case walls, base and top. You will have a well isolated case sound wise and will cut down the buzzing to be ignorable when listening.

[Bigman80]

Some of the hum will be the case resonating with the transformer. Start with getting some 10mm thick neoprene foam and put it on the top and bottom of the transformer. That will help de couple the transformer mechanically from the case.

Then get some "Dead mat" sound deadening sheets and stick it to the inside of the case walls, base and top. You will have a well isolated case sound wise and will cut down the buzzing to be ignorable when listening.Thanks!!

Good ideas.

[Primalsea]

Yes, some mechanical isolation on the transformer. Also is the transformer potted? If not you can place it on some mylar sheet or acetate heat laminator pocket and pump in some epoxy resin into the hole in the transformer. You will need to drill a hole for the fixing bolt.

[Bksabath]

22584
What is the transformer size ?

DC Blocker ? twist wires ? earth Bus ? (single wires from start point to one single point)
Earth lift ?

PS the Firebotle Vivant look really Gorgeous who is in charge for dusting and Polishing ? :D

Seriously where das he get those enclosures? I would really like one

[Bigman80]

Yes, some mechanical isolation on the transformer. Also is the transformer potted? If not you can place it on some mylar sheet or acetate heat laminator pocket and pump in some epoxy resin into the hole in the transformer. You will need to drill a hole for the fixing bolt.Ooh nice. Like this too.

[Bigman80]

22584
What is the transformer size ?

DC Blocker ? twist wires ? earth Bus ? (single wires from start point to one single point)
Earth lift ?750va

It's a mechanical hum. Will twisting the wires help?

[Bksabath]

Probably not but...
Is it there all the time or when under load ?
Traffo make ? (silly question)

[Bigman80]

Probably not but...
Is it there all the time or when under load ?
Traffo make ? (silly question)There all the time

Made by Airlink

[Bksabath]

I got a couple of 1000 VA from Canterbury (for the F5) and ,I did ask for audio Quality, they where making a racket, once you ear it you know is there, I complained and sent one back, It was sent away to be Vacum dipped and came back whit no Hum

If noise is there alla time probably same windings probably are not tight enough and dipping it may solve it ?

[Bigman80]

I got a couple of 1000 VA from Canterbury (for the F5) and ,I did ask for audio Quality, they where making a racket, once you ear it you know is there, I complained and sent one back, It was sent away to be Vacum dipped and came back whit no Hum

If noise is there alla time probably same windings probably are not tight enough and dipping it may solve it ?Dipping it? I've not heard of that.

[Bksabath]

They Put the transformer in a autoclave inside a bucket of varnish/laquer, same time under vacuum not sure about the temperature 150C ?
Heat and vacuum get rid of air trapped between windings and as it cool down the spaces are filled by the varnish this stop the vibrations alegedley :D

Quote from Airlink
Advanced Filter Power Supply



Avery Magnetics Advanced High Current 20A Filter
Primary to Secondary Copper Foil Antistatic Screen
Low Flux Density to Minimise Noise
Lacquer Dipped Cores, Primary and Secondary Windings



End quote

Did you get in touch whit them and told them about the Noise?

IMO if I ever buy a trafo that big again I try Toroidy

[Bigman80]

They Put the transformer in a autoclave inside a bucket of varnish/laquer, same time under vacuum not sure about the temperature 150C ?
Heat and vacuum get rid of air trapped between windings and as it cool down the spaces are filled by the varnish this stop the vibrations alegedley :D

Quote from Airlink
Advanced Filter Power Supply



Avery Magnetics Advanced High Current 20A Filter
Primary to Secondary Copper Foil Antistatic Screen
Low Flux Density to Minimise Noise
Lacquer Dipped Cores, Primary and Secondary Windings



End quote

Did you get in touch whit them and told them about the Noise?

IMO if I ever buy a trafo that big again I try ToroidyI have, they are sending a new one. I will make some effort to deaden the case too as that's in my capabilities

[Firebottle]

IMO if I ever buy a trafo that big again I try Toroidy

If you are buying from Toroidy make sure you order the correct spec.

They also make 'industrial' transformers that are not necessarily silent.

:)

[Bksabath]

Saving up for my next project
Papa F6
https://sklep.toroidy.pl/en_US/p/TTSAS0600-SUPREME-AUDIO-grade-transformer-TSAS600VA-voltage-to-50V/415
Got the capacitors most of the other bits and a 25Kg Copper heat sink already.

The heat sink is a real monster came out of 150 Kw Danfoss Inverter

Soon on those screens (well do not hold your breath):D

[Bigman80]

Their supreme range are fantastically well priced! I may have to indulge for my Monoblocks and Phonostage!!

[Bksabath]

Best thing about them ... No custom charge from overthepond
PS .off topic
Got the cables ... not tried them




22606

[Bigman80]

Best thing about them ... No custom charge from overthepond
PS .off topic
Got the cables ... not tried them




22606Ha, no worries.

[Bigman80]

Update,

After becoming increasingly frustrated with the audible buzzing from the TF I decided to get in touch with Airlink

They sent me a brand new TF and full apology for my problematic TF. I have sent the old one back and can confirm the new one is silent.

Excellent customer service from Mike.