First Gainclone

[Adrian]

I'm about ready to start replacing capacitors in my Crack and 2.1 S.E.X. amps and wanted to use something other than my tube amps to burn them in before I do the mods.

I just finished my first gainclone amp.  It is based on the LM3875 chip.  I'm using a 300VA Avel toroidal transformer with 25 VAC secondaries feeding the power supply which has a full snubber circuit.  I chose an Alps Blue Velvet Pot (looking for a knob now).

I've been using the amp with a Modi 2 (Schiit Audio) DAC fed from my desktop computer and have this running for about 24 continuous hours through a pair of small Klipsch bookshelf monitors.  It sounds very good.

Here's some pictures:

 

[Zimmer64]

Nice. Are these the Audiosector boards?

 

[Adrian]

Yes

 

[Adrian]

Got a technical question that probably belongs in another area but I'll put it here because it is for this Gainclone amp.

I want to install a power on indicator lamp.
I have a 110VAC, 0.44w LED lamp.  I plan to wire it in parallel with the transformer primary circuit so it will have 110VAC across it when the transformer is energized.

This simple parallel connection seems so obvious to me but I have not worked with this type of indicator lamp (LED).
Am I thinking right (parallel configuration will put 110VAC across the lamp AND the transofrmer when the switch is closed)?  Will both the LED lamp and the transformer "play well" together like this?
Like I said, this seem obvious but my gut is making me ask for confirmation or advice.

 

[Paul Birkeland]

It's hard to say without actually looking at the part's datasheet.

110V AC and LED's don't necessarily go that well together, but if that's what the switch wants, then it should work just fine. 

-PB

 

[Adrian]

Thanks for the reply, PB

I felt hesitant at first for the same reason.
The LED is rated for 110VAC and lights up with 110VAC.
So it appears the lamp has any necessary resistor/capacitor/additional diode, etc. to make it compatible for AC.

I'll have to wait for a week or so, but I'll clip it in across the primary circuit so it will be energized with the amp.
It's only a 4ma load - what can go wrong?
(Actually, the more I think about it the more obvious it is that this is the circuit configuration this LED lamp is designed for.)