T-amp Modifications (Singular)

by Alexander, Wednesday, November 16, 2005, 01:04 (1546 days ago) @ Alexander
edited by Alexander, Wednesday, November 16, 2005, 14:48

The seed of this project was planted by a buzzing article on TNT-audio about the Sonic Impact T-amp.

http://www.tnt-audio.com/ampli/t-amp_e.html

This 30$ plastic toy was presumably putting high end amps to shame in price/value. I could use a small amp for the iPod in the kitchen to power a pair of vintage B&O s45-2, so it seemed a fun experiment to get one. They where hard to track down. I finally found one on eBay for 40 Euro's incl shipping to Europe.

From the start the clarity of this 5 watt plastic box was a new experience. I discovered I only knew most of my music by half! My son put a feather up its behind.

At the suggestion of TNT-audio I already had a regulated 3-5 amp power supply to feed the plastic box. When I went to Bert I brought the amp with me, so he could have a listen.

No balls

To my amazement Bert hooked the plastic puppy up with his ORIS-Swing prototypes. "It lacks bass, this thing got no balls" was his first respons.

Battery power

Bert suggested that I switched to a bigger cleaner and faster power supply, a sealed lead battery, at least 7 Ah, with a 1 uF cap bridged. This made a noticeable improvement, but not a big one.

Power amplifier hack

At this point I had made contact with Leo van Doorn, who had build Das Veich with a Beyma fullranger and had tweaked the T-amp. He suggested a tweak by Nelson Pass, to add a 10 watt 47 Ohm after the amplifier to emulate the effect of a Power Transconductance Amplifier. I found more about this in a review at 6moons.com

http://www.6moons.com/audioreviews/firstwatt/firstwatt_2.html

The effect would tilt the response of the amplification, lifting the bass, at the cost of power. This sounded like a fun hack!

The effect was immediate! Even with the notch, the Singulars balans shifted to the other side. Very deep bass respons. Yet, its tiny 5 watts where used mostly to heat up the resistor. Clipping is unavoidable at a higher volume. Conclusion, not a good idea in a Fostex 206/T-amp combo.

New case

Searching the images in google with "T-amp" will give a substantial amount of t-amp enclosure tweaks. This box should benefit from a better volume-pot and connectors. I found a nice scheme and set to work.

http://talkgarden.tripod.com/si_5066_pg_7.htm

T-amps can be found in plastic, wooden and shiny metal tubes and boxes. They even have nice nicknames, like the Clari-T-amp and the Reali-T-amp. I found another nice box, to make my own Treasure-Amp:

It's a bit big, mostly air, but I had it lying around and has a proper use now :-)

The led is on the front, the switch on the back, routing the battery to either the amp, or the external plug for the charger.

New balls

Al this wood and iron would not give it a further bass boost. I found on the web that the lack of bass is part due to very tiny capacitors in the input signal. It's only logical. This amp is designed to power a set of small portable speakers of an mp3-player, not to waste energy boosting low bass. To do so, this amp has to grow up :-)

This link sets out different ways to modify the input.

http://www.michael.mardis.com/sonic/inputmods.htm

I changed only the SMD caps for nice new ones I got as a gift from the nice fellas at hifi-shop "De Groef" in Groningen.

The amp is much more mature now, a lower voice, but still lacks experience. A recent review of different Tripath based amps got me interested in the bigger brothers of the chip used in the Sonic Impact, like the Charlize print from DIYparadise.com

http://www.tnt-audio.com/ampli/tripath_amps_e.html

But for now I take a tweak break and enjoy the result. If you sticked to the story all this way, I thank you for your interest.

Comments are welcome.

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