THE BLOG

14
Aug

Plamen’s LM3886 Gainclone

Concept:

As this was my first DIY amplifier I decided I need to create something easy to assemble yet good sounding. I started to plan the build. After some reading I decided to use the schematic posted by Alex Wong for 2x LM3886 per channel in parallel

A DC speaker protection circuit is added and therefore I needed another small transformer to power it. I also added and EMI filter before the transformers which greatly reduced the hum I can hear from the speakers.

PSU:

As this is not a top-notch sonic quality amplifier I decided not to spend a fortune on the PSU. I also think that this particular amplifier won’t sound much different with a regulated PS. I don’t have schematics for the PS, but it’s just a 400VA 2x25VAC toroidal transformer > 2x 20A rectifiers with each diode shunted with a 10nF cap > 8x 4700uF 50V Low-ESR caps. If you decide to build a Gainclone I can tell you that the filter capacitors in the PSU have tha largest impact on the sound characteristics of the amplifier so be sure to experiment a bit with their capacity/type. All AC cables are twisted to reduce noises. The yellow DC cables are made of 1.5mm2 solid core OFC.

Enclosure:

I really wanted a good and solid enclosure which still doesn’t look like most of the DIY amplifiers I see on the internet. I really liked the enclosures Alex Wong uses in his projects, especially BPA300, but I really didn’t feel like paying 100$ for an enclosure of a 100$ amplifier… So I decided to DIY a bit. The floor and the right side of the box are cut from leftovers of a laminate flooring from my apartment using a regular cutting saw table and then put together using little aluminium profille that I had lying around. The heatsinks are then screwed to the lower panel.

The upper/lower/front panel is made of a bent material called Etalbond but black or white plexiglass will look even better. As you can see the potentiometer is put on a L-shaped piece of aluminium bolted to the wood panel and it’s shaft goes through a hole in the front side of the Etalbond/Plexiglass panel.

Conclusion:

I had a great fun building this amplifier and I recommend it to beginner/intermediate users of the DIY audio scene. It sounds good, especially with a tube preamplifier. I’m sure you don’t expect that sound from a chipamp, but LM3886 and LM1875 are really good. I gave this amplifier to my brother as a present because I am planning to build my next solid-state amplifier in the next few days. Thank you for reading, now grab the soldering iron and do something cool!

14
Aug

Hello and welcome to my new blog. In this blog I will be posting information mainly about my DIY audio components and any other geek stuff that I come across or build. Thank you for visiting!