Saturday, May 22, 2021

"Quiet Strom (take II)" - `100W Class D Tripath amplifier


This amp has been put together from most parts on hand. The enclosure once held SS amp and has a good PS including 20,000uf of smoothing caps. The T4 module has a further 10,000uf Nichicon filter cap onboard. This amp module is a T4 Tripath module and with an appropriate tranni will deliver 180Wpc. The PS will deliver 100W and with even low efficiency speakers will play loud.

The smart looking two tone enclosure is steel and Al. The IEC socket also has a RFI/EMI power filter. It is fused (internal) and earthed. Silver plated wire-warp wire is used in the signal path. The amp is dead silent with music off and is highly detailed. Bass is deep and extended and very well controlled. Very good use of parts which have been unused for so long. 

Wednesday, May 19, 2021

"Cello" - TDA7293, chip based 100W amp


Chips for power amps are continually improving. The TDA7293 is capable for 120W in my configuration this amp will produce 100W. The kit comes with all components, PCB, heat sink etc. The PS is onboard and all that is required is a 30-0-30V tranni. I used a 300VAC toroid because I had it on hand. 

The enclosure is two tone steel and Al and is very solid.  Solid brass gold plated speaker binding posts with quality RCAs. Hookup wire is all Cat5 twisted pair with no shielded wire. Not required. The enclosure is earthed and fused. The sound is extremely balanced and very engaging to listen to. Bass is very extended and well controlled. At low to medium volumes THD is 0.001%  

The overall sound is very dynamic and challengers my more powerful amps which cost three times the price. The amp module kit is $A15 delivered. Hard to beat. Of course the main cost is the tranni and enclosure. Very impressed.

Sunday, May 2, 2021

Mimic - Custom, chip based MM RIAA phono preamp


Yet another chip (OPA2134) based phono stage. Most parts were on hand and in this build I used Russian PIO 4uf (snubbed) caps on the output. Metal film resistors here where in other builds I have used carbon. Other caps are a mix of MKT - for accuracy - and Polyester. Once more there is no PCB but a very small piece of vero-board. Differential PS in on board and two 9V batteries power the unit. Silver plated hookup wire (wire wrap) and WBT silver based solder is used. With quality batteries 50 hours of play can be expected. 

The metal enclosure is deadened in the lid and under the bottom with bituminized heavy Al. This adds weight to an otherwise light metal (Al and steel) enclosure and also dampens any resonances. There is  an earthing point and an external battery test point. The overall sound is very neural and dynamics are outstanding. The preamp is dead quiet with good gain. Simple and over-achieving.