Mini BMU

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Dr Bunsen Honeydew
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Mini BMU

Unread post by Dr Bunsen Honeydew » Thu Apr 12, 2018 6:36 pm

I really need a BMU here because of my noisy mains making transformers rattle, BUT I am really subject to available room around my test system as it is always changing as to what I am building. Sooo I bought a smaller balanced transformer, 300va instead of 1000va and put it in a A40 box without the heatsink normally used with that box, just put a base plate on the top as well as the bottom. No room and too much hassle to put mains sockets on it so I cut the plug off one of my extension leads and hard wired it into the box, and of course a mains lead to the wall hardwired in as well. It is smallish and I can keep it out of the way and I have four sockets on the extension lead.

Early days, only running it in at the moment on a Phono1mc - P50sa - A20 - Cube2. Playing Wish You Were Here - Pink Floyd - rather nice.
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Fretless
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Re: Mini BMU

Unread post by Fretless » Fri Apr 13, 2018 10:47 pm

This is very intriguing Doc. Any idea of a likely price?

Also, how could you fit Schuko plugs/sockets? Or could it be delivered with a lead where someone could fit their own socket set?
NVA: P50sa - SSP - A40 - LS6 - Cube3
Digits: RPi 2B/Allo DigiOne/Volumio/Tomanek ULPS/AQ Jitterbug
CD Transport: Cambridge CXC DAC: Metrum Acoustics Musette
Headphones: AQ Nighthawk Carbon H/P Amp: Schiit Magni 3

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terrybooth
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Re: Mini BMU

Unread post by terrybooth » Sat Apr 14, 2018 7:35 am

I guess the answer the the last question would be no because it would not meet CE regs.
Pioneer PL71/DL103/ Phono2/HiFiPi/P90SA/TIS/CubixPro two-up

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Dr Bunsen Honeydew
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Re: Mini BMU

Unread post by Dr Bunsen Honeydew » Sat Apr 14, 2018 2:25 pm

*IF* I ever make it for others, as at the moment it is just for me with botched case. It would have two hard wired flying leads, one to the input mains plug and one to a four way distribution block. Could be EU or UK. Both perfectly legal
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Dr Bunsen Honeydew
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Re: Mini BMU

Unread post by Dr Bunsen Honeydew » Sun Apr 22, 2018 2:32 pm

I have been using this for over a week and I am really taken aback. I expected it not to be a patch on the big one musically but just help with my noise problem, but it does a large portion of the musical benefit of the big one. I am using it because my mains is so bad that I prefer to use the smaller amps here to cut down on transformer noise, using the standard BMU it just transfers the noise to the big 1000va transformer in it. So the BMU becomes irritatingly noisy, I tried a DC blocker but then the music suffered a little, so I just didn't use one here, which was daft.

So the solution is the mini BMU. At 300va the transformer is very quiet and you can hardly hear it unless you put your ear up to it. AND you can use two or more of them if worried about having too much VA in your system, but please don't add all transformer VA up and say that is what you want, completely wrong!, remember that power wouldn't be drawn even if you left the system on full volume, people use bigger transformers because they make better music (less mains source impedance).

So I am going to have to put it in production, something I only built for myself. I still recommend the big one unless you have the same problem as me.

The standard unit is £500 until the end of the month, then it goes up to £550. On my costing I can do the mini BMU for half that, so £250 until the end of the month then £275.
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Classicrock
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Re: Mini BMU

Unread post by Classicrock » Sun Apr 22, 2018 3:53 pm

I'm wondering if the mini version would give better results in my system than the big one did? Also not such a big weight to hunk about.

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Dr Bunsen Honeydew
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Re: Mini BMU

Unread post by Dr Bunsen Honeydew » Sun Apr 22, 2018 4:10 pm

I don't know but at the mo if you want to try you buy one and send back for refund if unhappy.
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