Sonic Impact

The Portable T-Amp

This amp was a personal amp that I have owned for many months. It typically sits on top of my computer tower and drives my computer speakers.

A buddy of mine and I ordered a pair of these amps when a special was run on them for $40. for a pair of them, shipping included. Yep, this amp was $20.

It has had some very basic mods.

It comes with small plastic clips in the rear for sliding in bare speaker wire. Not only are these a poor connection but easily broke when trying to slide in one side of a spade connector. The speaker output connectors were removed and holes were drilled into the back of the unit to allow mounting some standard GR Research binding posts.

There was also a small 140 pF cap that shunted across the outputs. This was replaced by a small but larger value Sonicap Gen.2 capacitor.

The amp sounds best when battery powered but when driving the amp hard the batteries only last 3 or more hours.

For the comparisons it was run off of an inexpensive Radio Shack wall wort.

High quality interconnects were used for the comparison but this amp does not have RCA inputs. So the high quality interconnects were plugged into a barrel connector that coupled it into an RCA to 1/8" plug adaptor.

Technical parameters:

.04% THD+N @ 9W, 4 ohms.

.18% IHF-IM @ 1W, 4 ohms.

11W @ 4 ohms,. .01% THD+N

6W @ 8 ohms., 0.1% THD+N

High Power:

15 W @ 4 ohms 10% THD+N

10 W @ 8 ohms 10% THD+N

High Efficiency:

81% @ 15W, 4 ohms

88% @ 10W, 8 ohms.

Dynamic Range = 102 db


GR Research Inc.
910 North Jackson
Iowa Park, TX 76367