Superbly-built LM3886 on EBay

linuxguru · 1st May 2011, 10:43 AM

Title of the item includes the text "diyaudio" - the unit itself seems to be very meticulously designed and professionally built; a superb visual treat. Here's the EBay listing:

LM3886 HIFI Audio Power Amplifier Digital AMP DIYAUDIO | eBay

It's probably not a MyRef, though it does seem to have an opamp driving the LM3886s and an additional opamp as the input buffer.

Has anybody bought one, and what does the schematic look like?

cats squirrel · 10:59 AM

Its a pity they have to call it a digital amplifier, as if things won't sell, now, unless they are digital!!

If they have got this fundamental wrong, what else?

AndrewT · 1st May 2011, 01:18 PM

Those are the same extrusions as in the cases I bought.
Different holes in the front and back panels and no ventilation in the base nor cover.

I hope that the transformer is 20+20Vac or less, else I foresee the chassis and it's contents getting very hot on 4+4ohms in summer.

Looks neat and tidy.

Any idea what the two To220 are for?

tuhkam · 1st May 2011, 02:29 PM

I'm I getting it wrong or did they realy leave the case without earth connection (3rd AC input pin unused). Somehow I had the impression that if this is done, a whole lot of other safety features become mandatory (non conductive enclosure etc - resulting in something like a laptop PSU).
If it arrives by post (having traveled from the other side of the world by various means of transportation) I would first poke the "ON" button with a wooden stick, just in case some wires have come loose and are making contact to the enclosure. Also the plastic coated LM3886 version might have been safer in this kind of configuration.

AndrewT · 1st May 2011, 02:59 PM

Hi T,
well spotted !
There is no attempt to double insulate any of the mains wiring nor to double insulate any of the low voltage wiring.

I shall ask a question about ClassII regulation compliance.

TheLaw117 · 1st May 2011, 04:47 PM

Quote:

Originally Posted by AndrewT

Those are the same extrusions as in the cases I bought.
Different holes in the front and back panels and no ventilation in the base nor cover.

I hope that the transformer is 20+20Vac or less, else I foresee the chassis and it's contents getting very hot on 4+4ohms in summer.

Looks neat and tidy.

Any idea what the two To220 are for?

I think they are voltage regulators for the DIP preamps.

fingerboy21 · 1st May 2011, 05:04 PM

That build looks pretty darn good!

1st May 2011, 10:43 AM	#1
linuxguru diyAudio Member Join Date: Sep 2007	Superbly-built LM3886 on EBay Title of the item includes the text "diyaudio" - the unit itself seems to be very meticulously designed and professionally built; a superb visual treat. Here's the EBay listing: LM3886 HIFI Audio Power Amplifier Digital AMP DIYAUDIO \| eBay It's probably not a MyRef, though it does seem to have an opamp driving the LM3886s and an additional opamp as the input buffer. Has anybody bought one, and what does the schematic look like?

1st May 2011, 10:55 AM	#2
cats squirrel diyAudio Member Join Date: Feb 2011 Location: Devon, UK	Its a pity they have to call it a digital amplifier, as if things won't sell, now, unless they are digital!! If they have got this fundamental wrong, what else? Last edited by cats squirrel; 1st May 2011 at 10:59 AM.

1st May 2011, 01:18 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Those are the same extrusions as in the cases I bought. Different holes in the front and back panels and no ventilation in the base nor cover. I hope that the transformer is 20+20Vac or less, else I foresee the chassis and it's contents getting very hot on 4+4ohms in summer. Looks neat and tidy. Any idea what the two To220 are for? __________________ regards Andrew T.

1st May 2011, 02:59 PM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi T, well spotted ! There is no attempt to double insulate any of the mains wiring nor to double insulate any of the low voltage wiring. I shall ask a question about ClassII regulation compliance. __________________ regards Andrew T.

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1st May 2011, 02:29 PM	#4
tuhkam diyAudio Member Join Date: Nov 2010	I'm I getting it wrong or did they realy leave the case without earth connection (3rd AC input pin unused). Somehow I had the impression that if this is done, a whole lot of other safety features become mandatory (non conductive enclosure etc - resulting in something like a laptop PSU). If it arrives by post (having traveled from the other side of the world by various means of transportation) I would first poke the "ON" button with a wooden stick, just in case some wires have come loose and are making contact to the enclosure. Also the plastic coated LM3886 version might have been safer in this kind of configuration.

1st May 2011, 05:04 PM	#7
fingerboy21 diyAudio Member Join Date: Dec 2010 Location: New Hampshire, USA	That build looks pretty darn good!

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