View Full Version : Quick check - Airlink BMU - which one?
jandl100
20-01-2018, 07:58
I've a 500VA Airlink atm which I bought used from ebay - and it's bloody marvellous.
But thinking of upping it to a 2000VA or 3000VA model.
Sensible?
Which one? - any gains from 3kva over 2kva when kit is using far less than either?
With conditioning or unconditioned?
Ta :)
(I'm sure this has been covered elsewhere - but there's about 10000 pages on the forum about it :doh:)
Primalsea
20-01-2018, 08:40
You could phone Airlink and ask to speak to someone in Technical and tell them want you want to do and if you have any specific issues you want to address using the BMU. One big unit may be the way to go, or it may be better to have smaller units and segregate some pieces of hifi from each other, say those with SMPS and those with linear. Filtering is good but differential noise is dumped onto the mains ground, so they may be able to advise the best way forward for you.
Hi Jerry,
The higher the KVA rating the lower the thempedance (so they say), so 3KVa is the one Id go for.
Might not be night and day but why not?
Also, I’d go for unconditioned as the balanced mains benefits are seperate from conditioning “benefits”, and any power conditioner Ive tried has affected the dynamics in amps.
Based on my own experience, I would tell anyone to stay away from mains conditioners.
If going for the hardwired bmu version, pay attention the to electrical safety aspects mentioned, and get a DC blocker fitted too while the works being done.
Hope this helps.
jandl100
20-01-2018, 09:23
Thanks Gaz
Unconditioned 3kva non-hardwired sounds like the way to go for me.
Thanks Paul
Interesting point about using more than one.
I'll try using the 3kva for the power amps and the old 500va for DAC etc.
Jerry, if you do a search for balanced mains and me you should find the unit I have - which is what you are describing.
jandl100
20-01-2018, 11:24
Jerry, if you do a search for balanced mains and me you should find the unit I have - which is what you are describing.
Thanks Mark
I tried that search and failed to come up with anything useful!
Primalsea
20-01-2018, 13:30
Thanks Paul
Interesting point about using more than one.
I'll try using the 3kva for the power amps and the old 500va for DAC etc.
SMPSs have filters built into them but these are to try to stop noise from the supply getting onto the mains, not clean the mains going into the supply. They do achieve this, but not only to a level that is required buy the emission regs, and I suspect that cheap SMPSs don’t meet this. To isolate and clean your mains just to connect equipment that then pollutes it is a bit counterproductive, so make sense to try to isolate anything that could put noise on to you cleaned mains.
The bigger the transformer the more likely you will get unit hum. They are also big heavy ugly units. When I used balanced mains I used a 2kva unit, which is rated at 8.6 amps continuous current, more than enough. 500va should be used for sources and pre, but not power amps.
I used the hardwired version straight into a 6 way Olson mains block, the Airlink BPS2020.
Interestingly this unit has the same spec that I got fitted to mine a few years ago i.e. an RCBO on the output. Guess a lot of us asked. :P
Wouldnt suggest a BM unit without a DC blocker in there somewhere as yes, they can hum.
On current rating, a Krell KSA-100, 100W of pure class A, draws 5.8 amps at the wall, which is about as extreme as it gets. Normal entire setups are drawing way less, well under 3 amps.
jandl100
21-01-2018, 14:32
I've ordered a 3KVA Airlink, unconditioned.
I already run a DC blocker, so hopefully should be OK hum-wise ... we need a fingers crossed smilie!
Thanks Mark
I tried that search and failed to come up with anything useful!
It’s here mate: http://theartofsound.net/forum/showthread.php?53809-I-ve-just-bought-a-balanced-transformer!
I’m not saying it’s useful though ;). You’ve probably bought the same one as I have - blends seamlessly into any domestic environment.....
jandl100
21-01-2018, 15:08
It’s here mate: http://theartofsound.net/forum/showthread.php?53809-I-ve-just-bought-a-balanced-transformer!
I’m not saying it’s useful though ;). You’ve probably bought the same one as I have - blends seamlessly into any domestic environment.....
Ah, OK - you got one of these ...
https://i.imgur.com/zW8rAwil.jpg
Too industrial for me.
I've bought one of these ....
https://airlinktransformers.com/images/products/552_photo1_UK2000.jpg
I've ordered a 3KVA Airlink, unconditioned.
I already run a DC blocker, so hopefully should be OK hum-wise ... we need a fingers crossed smilie!
Will be more than good enough!
Ah, OK - you got one of these ...
https://i.imgur.com/zW8rAwil.jpg
Too industrial for me.
I've bought one of these ....
https://airlinktransformers.com/images/products/552_photo1_UK2000.jpg
It may look "too industrial", but the provision of a ganged double-pole RCB on the output is, IMO, essential for complete protection and safety.
jandl100
21-01-2018, 19:52
Too late - I'm doomed. :(
Bigman80
21-01-2018, 20:12
Isn't that button on the front a trip reset? Surely has a cutout inside the box??
Bigman80
21-01-2018, 20:18
22545
Yes it is. Don't worry, Jerry. It's spot on in safety terms.
Isn't that button on the front a trip reset? Surely has a cutout inside the box??
Hard to tell from the photo - what does the manufacturer say?
It is not sufficient to have an overcurrent protection device on the input (primary) alone.
Bigman80
21-01-2018, 20:27
Hard to tell from the photo - what does the manufacturer say?
It is not sufficient to have an overcurrent protection device on the input alone.I've posted the specs above, Barry.
Bigman80
21-01-2018, 20:29
It's a thermal Circuit breaker BTW.
I've posted the specs above, Barry.
Yes I know - and I would still prefer to see fast-acting protection devices fitted to both the primary and secondary side of the transformer.
Bigman80
21-01-2018, 20:35
Yes I know - and I would still prefer to see protection devices fitted to both the primary and secondary side of the transformer.Ah, I didn't know if you had seen it.
Prefer......yup,
Necessary......nope,
Well, according to the CE anyway.
Thing is that balanced mains aren’t usually used at home... there is a potential fault condition where a fuse blows in the live phase, but you could still have 120V across neutral. This is why RCBOs are used on the secondaries, it would detect this fault condition. Don’t forget that the gear is no longer bonded to earth, but bonded to the centre tap of the secondary.
Thing is that balanced mains aren’t usually used at home... there is a potential fault condition where a fuse blows in the live phase, but you could still have 120V across neutral. This is why RCBOs are used on the secondaries, it would detect this fault condition. Don’t forget that the gear is no longer bonded to earth, but bonded to the centre tap of the secondary.
Yup.
RCBO’s on primary and secondary would be (and was) my choice.
Thing is that balanced mains aren’t usually used at home... there is a potential fault condition where a fuse blows in the live phase, but you could still have 120V across neutral. This is why RCBOs are used on the secondaries, it would detect this fault condition. Don’t forget that the gear is no longer bonded to earth, but bonded to the centre tap of the secondary.
Which in turn is connected to the mains earth, or should be. Otherwise your are correct in what you say.
Also there could be a fault with partial insulation breakdown (surface tracking) such that a leakage current of more than 30mA is drawn from one side of the transformer secondary winding. This leakage current will thus in turn be drawn from the primary, but will not be a 'residual' current as it will flow equally in the live and neutral wires of the (unbalanced) primary side, so any RCBO fitted in the consumer unit will not be affected and will not operate under this fault condition.
westsidejon
18-02-2018, 22:48
Hi Jerry
How did you get on the Airlink balanced power supply? I'm thinking of getting one for my active speakers and digital front end.
Jonathan
I have mixed feelings about mine.....
Bigman80
19-02-2018, 10:11
I have mixed feelings about mine.....Do tell
Ammonite Audio
19-02-2018, 10:39
I have a 2kW Airlink BMU and it offers a considerable improvement in tone/texture/detail etc, but it did somewhat 'go off' after a while. Out of curiosity I replaced the SL32 surge-limiting thermistor (the big black disc thing) with a new, identical component and the magic came back, in an instant. So, this leads me to suspect that these BMUs are probably better off with a proper 'slow start' circuit, such as the one that Sjostrom Audio (http://sjostromaudio.net/shop/mains-circuits/10-sst03-softstart-for-toroidal-transformers.html) sell as a bare PCB, to limit inrush current, rather than a thermistor. Sadly, there is no room in the case of my Airlink BMU for that circuit.
Do tell
Sorry, only just seen your response. Well, it’s just that even at 3000Va I’m not sure it doesn’t quash dynamic swing a bit. I’ve diacussed this with Hugo before (Ammonite Acoustics) and he puts it down to the thermistor but I’ve not had time to experiment.
Bigman80
19-02-2018, 22:30
Sorry, only just seen your response. Well, it’s just that even at 3000Va I’m not sure it doesn’t quash dynamic swing a bit. I’ve diacussed this with Hugo before (Ammonite Acoustics) and he puts it down to the thermistor but I’ve not had time to experiment.Hmmm, not had any issues with mine at 750va.
Hasn't got rid of the noise the powerline adapters are producing though.
Hmmm, not had any issues with mine at 750va.
But are you sure...... .. .
Bigman80
20-02-2018, 12:48
But are you sure...... .. .Yes. I took it back out this morning and put a homemade multiblock in instead. Lost the clean lines very slightly and felt everything was little less defined as a result. Put it back in and instantly improved.
My issue could also be down to running my power amps through the BMU (although it should, in theory, easily be big enough to cope).
Yes. I took it back out this morning and put a homemade multiblock in instead. Lost the clean lines very slightly and felt everything was little less defined as a result. Put it back in and instantly improved.
That’s a very good description of what it does improve - I’m not saying it isn’t without benefit, just that it isn’t also without some compromise...
Bigman80
20-02-2018, 19:32
That’s a very good description of what it does improve - I’m not saying it isn’t without benefit, just that it isn’t also without some compromise...True, as with all things mate. Nothing is perfect.
It could also be down to having my power amps connected, or to Hugo’s suggestion - or to a combo of both.
Bigman80
20-02-2018, 20:06
It could also be down to having my power amps connected, or to Hugo’s suggestion - or to a combo of both.Could be, I do have everything plugged into the BMU regardless of the fact people recommend plugging the Amps directly into the wall. Just seems better that way to me.
Stratmangler
21-02-2018, 00:07
Hasn't got rid of the noise the powerline adapters are producing though.
Have you tried a ferrite snap clamp on the feed to the BMU?
Bigman80
21-02-2018, 00:08
Have you tried a ferrite snap clamp on the feed to the BMU?I haven't. Think it'll work?
Stratmangler
21-02-2018, 00:27
I haven't. Think it'll work?
It might.
They can be picked up cheaply enough, so not much lost if it doesn't.
Bigman80
21-02-2018, 08:39
It might.
They can be picked up cheaply enough, so not much lost if it doesn't.Cheers, I'll give that a go.
That’s a very good description of what it does improve - I’m not saying it isn’t without benefit, just that it isn’t also without some compromise...
I would tend to concur with your observation Mark, ABA-ing with Ballanced mains has manifest areas of improved fidelity viz sound stage, quality and density of base notes, dynamic swing etc.etc however that has traded off against a smidgin less finite micro detailing, particularly noticable on live recordings featuring an audience in the background, and a touch less nuance to the inflection of phrasing on vocals.
Bigman80
21-02-2018, 12:01
I would tend to concur with your observation Mark, ABA-ing with Ballanced mains has manifest areas of improved fidelity viz sound stage, quality and density of base notes, dynamic swing etc.etc however that has traded off against a smidgin less finite micro detailing, particularly noticable on live recordings featuring an audience in the background, and a touch less nuance to the inflection of phrasing on vocals.I'm really surprised by people's experiences in this subject. The BMU has increased the audibility of the micro detail in my system. The noise floor is lower, everything is better placed and spaced and the depth of the bass noticeable lowered too. I was a non believer in this sort of thing until a friend bought a N** BMU and reported his findings. He is a guy I have a lot of respect for and his finding prompted me to invest in a DIY unit. I simply won't be without it now, such is the impact it's had.
Blueflash
21-02-2018, 18:34
I'm really surprised by people's experiences in this subject. The BMU has increased the audibility of the micro detail in my system. The noise floor is lower, everything is better placed and spaced and the depth of the bass noticeable lowered too. I was a non believer in this sort of thing until a friend bought a N** BMU and reported his findings. He is a guy I have a lot of respect for and his finding prompted me to invest in a DIY unit. I simply won't be without it now, such is the impact it's had.
+1 for me on the above. Have found improvement across the board. One of the things I noticed about live recordings was the crowd was more audible and coherent as opposed to crowd on the left, crowd on the right without the BMU.
I think a lot of the complaints against them could be sorted by having a big enough one. I have 4KW to power both ATC 50A`s and 2KW for the sources.
Bigman80
21-02-2018, 18:36
+1 for me on the above. Have found improvement across the board. One of the things I noticed about live recordings was the crowd was more audible and coherent as opposed to crowd on the left, crowd on the right without the BMU.
I think a lot of the complaints against them could be sorted by having a big enough one. I have 4KW to power both ATC 50A`s and 2KW for the sources.Whether I'd go bigger, I don't know. The benefits v cost is an odd one. The one I made (with help) is providing probably as big an improvement as anything else I've done to this point.
The draw on the current also is well below it's capabilities so why worry [emoji6]
At this minute I have my phonostage going through my BMU but with all the amps (and TT PSU) going directly to the mains.
Bigman80
21-02-2018, 19:41
At this minute I have my phonostage going through my BMU but with all the amps (and TT PSU) going directly to the mains.I know that's the projected wisdom but sounds better in my house with the amps in the BMU. No idea why though.
Have you tried that?
Do you mean with the phonostage direct in the mains and everything else through the BMU? No, not tried that yet - just the whole system through the BMU, nothing through the BMU and just the phonostage through the BMU (my BMU is really massively over specified for just the phonostage).
Bigman80
21-02-2018, 20:21
Do you mean with the phonostage direct in the mains and everything else through the BMU? No, not tried that yet - just the whole system through the BMU, nothing through the BMU and just the phonostage through the BMU (my BMU is really massively over specified for just the phonostage).I meant everything in the BMU. also, daft question, does your BMU have enough sockets to accommodate everything or do you use a block plugged into it?
Oh yes, I’ve tried everything in the BMU :). I use a custom built Hydra style distribution block - designed and built by myself!
This and another double headed lead:
https://i.imgur.com/PIaTpaYl.jpg
Yep, you need eight mains leads to play a record at my house!
Bigman80
22-02-2018, 00:29
Oh yes, I’ve tried everything in the BMU :). I use a custom built Hydra style distribution block - designed and built by myself!
This and another double headed lead:
https://i.imgur.com/PIaTpaYl.jpg
Yep, you need eight mains leads to play a record at my house!I love that. "Hydra" is perfect naming too.
Hmm, not sure what else to suggest. Truth is I haven't really done anything else with mine as I was happy straight away.
It’s OK, no need to suggest anything :), it all sounds pretty extraordinary as it stands.
It could be my Naim amps don’t like the grounding arrangement or/and there are three 400VA transformers and a ton of reservoir capacitance. In fact there are loads of variables :).
Bigman80
23-02-2018, 09:42
;)
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