Tiny stereo amp build:

hydrovac

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Until about a year ago, I used an Altec Lansing setup on my PC. The sound isn't great, and especially so once the subwoofer died. Since then, I've been struggling along with just two of the little, tinny-sounding plastic things on my desk.
Time to upgrade. Bought a Zhaolu D3 DAC off the forum, and picked up a pair of JBL Control One monitors from the dealer. As I listen in the near field (about 1 meter between my ears and each speaker cabinet) amp power is not a concern. Lacking an amplifier, and not wanting something the size of a VCR on my desk, I decided to build a tiny low watt amp from a kit, and fabrication, heat sinks, power supply, enclosure, connectors etc.
So here goes! I was looking for a pretty easy desktop amp to build, a pure Single Ended class A design because it has the more desirable even order harmonics......and has no cross-over distortion. My vote..... would be for a Nelson Pass design. NP designs are solidly engineered and they usually sound fantastic with many different rigs. If the ultimate goal is musicality, the NP designs are well proven and there is a wealth of information and variation out there for you to try. I'm focusing mostly on Nelson Pass' published plans because they're simple and therefore somewhat easier to build. Design elegance also tends to lead to better sound, since there are fewer elements corrupting the signal.

All in all its a fun project. The simple chassis built around the heat sinks. It is about construction techniques, to take an existing PCB-based component and put it in a box. Overall, the look is pleasing and hopefully somewhat different enough to be interesting.

Will post the listening impressions after completing the build.

Thanks for reading







 
I hope the Hum is contained ? For such small enclosures with the transformer so close to the signal path, you have to be careful.
Take care :)
 
Got the panels back from painting. Told the powder coating guy to apply whichever shade that was going on, in the current batch. Resulting in Ivory finish.
Few pics of the finished cab.





Found these in my kitchen renovation project hardware. Nice buttons with curved base.





The mains cable will be through a cord gripping grommet. - Compact but difficult to fit, requires an oval hole and can damage cable if fitted too tight.







Will be posting listening impression soon.
 
Nice looking enclosure,but some vents would have been better.It gets hot,like other class A.Please keep an eye on temperature.

Regards,
Sachin
 
This looks fantastic. Might put something like this on my desk one day instead of thinking about actives.

Any listening yet?
 
My main reason for posting, other than bragging about finishing the amp, is to let potential builder/owners know how it sounds with a modest system. Source is JPlayer from PC USB to Zhaolu D3 DAC to ACA and JBL control 1 monitors.

The amplifier sounds great with the three different set of bookshelf speakers I tried. With high-sensitivity speakers it will get quite loud, yet still remain well behaved and pleasant sounding. If you push it too hard at the input, you will start to hear distortion when the amplifier hits its limits. But since this design is intended as the driver for a small bookshelf system, it is unlikely you would push that hard.

The sound is very natural, with an inherent rightness and musicality which I find pleasant. Even after prolonged listening there is no listening fatigue. You simply forget the installation and you are drawn into the musical performance. Orchestral recordings sound good, but in loud and complex passages you notice that the amplifier runs out of steam. This is not an amp for head bangers or rock-and-roll addicts. This is for quite small rooms in near field listening. With Lowther or Fostex speakers the amp may fill a bigger room with sound. Small details are reproduced surprisingly well. Small bells and triangles, harp sounds in the back of the orchestra, voices sound very good - there is no trace of cross-over hardness or sibilance. The proverbial "veil" between you and the sound seems to be very thin or absent.

I consider this amplifier a good introduction to single-ended designs. Hobbyists who dont like to pay a lot of money for their first attempt at SE amp building may try it and get hooked. You can build a copy of this amp for approx Rs.4000/- and have lots of fun. If you like it, you will probably proceed to a Zen amplifier (Nelson Pass), or a single-ended tube design.

Cheers!





 
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<snip>Small bells and triangles, harp sounds in the back of the orchestra, voices sound very good - there is no trace of cross-over hardness or sibilance (this is pure class A, remember?)<snip>
Can you please explain this? What cross-over hardness? And I always thought tweeters exhibited sibilance and not amps.
 
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Keith,

Pardon for mixing up impressions. but I was referring to JBL control 1 monitors. They sound, for the most part, extremely natural and uncolored. The overall sound was rich and luscious, I noticed that all sibilant passages were prominent without being bright, and with levels of articulation... clean and well defined, implying freedom from treble grain and hardness or harshness whatsoever.

Cheers!
 
@Hydrovac

The looks are stuning and audio experience must have been as well so :) Well done :D

Where you got the kit and do you mind posting details about BOM and schematic (i know you mentioned it about 4k), does this include everything including cabinet and PS ?
 
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