DIY gainclone amp

[drf]

Due to illness in the family my last amp project had to get put on hold (mainly becasue it was a very time intensive project). However recently I have found enought time to do a smaller easier project.

A gainclone with 20Watts per channel. The basis for the amp is the 20watt amp kit from Australian electronics store Jaycar. These kits are very well designed and have exceptional specs. As all the ground work was done all I had to do was design a powersupply and case.

After calculating the max load and allowing for transients I decided to just overkill the powersupply with a 160VA torioidal. This allows for 4.4amps per rail.

The first listening test was done and the result was simply amazing. Although I was happy I wanted an unbiased opinion so I asked my wife to sit in and tell me what she thinks. After a minute of listening she asked if the drum track could be mixed in better as it sounded seperate to the rest of the instruments. I was playing an MP3. After some thought it occured to me that if the sound stage in my studio was clear and defined enough to hear the different tracks in the recording then the amp at least is not the weakest link in my system.

Some measurements:

the source sound wav:

60Hzsource.jpg

and the measurement from the speakers:
60Hzmeasure.jpg

I understand room interaction and all that, however the bit I am interested in is the transition between the positive and negative side of the wave. As you can see althought the wave is slightly distotred (I believe this is a damping issue) there is very little delay or bias issues during the transition. My last amp had the exact opposite issue, it had poor transition but good speaker control.

EDIT: I thought I better clarify a point before people ask, yes I do measure from the speaker and not directly from the output of the amp, this is so I can gauge how well the amp is controlling the speaker.

[terry j]

did you get all the parts from Jaycar?? and did the kit at least have suggestions on the PS or do you have to know your stuff and design it y/self?

Price and link??

thanks DRF, hope the wife is well right now.

[drf]

Here is a link to the 50W version, I couldn't find the 20Watter on their website. They are almost identical except for the chip and power supply requirments. The instructions have a recomended PS schematic which is more than adequate, I just like to tinker so I couldn't help myself. Excluding case you should get change out of $150 for enough parts to build a 2ch. 50W amp.

Yes all parts came from Jaycar,

My Wife is doing sort-of O.k at the moment. We have an appointment with the oncologist this week to find out why she has fluid in her lungs.

Cheers