Here is some more fodder for the digital amp mavens, and the Tripath subject in general.

Last week Vinnie Rossi sent me a prototype battery powered Tripath amp based on the chip found in the PowerWave and Sonic Impact, the 2024, I believe it is. He has worked hard on optimizing the signal path, using audiophile grade electrical components, employing a few discoveries made along the way.  The unit came in a natty black powder-coated aluminum case, with machined aluminum volume control and spiffy blue LED 'on' light on the front. I should mention that my absolute first impression of the amp was its fit n finish. Vinnie did a really nice job on this Tiny Terror.

Initial Sonic Impressions

Zero Noise. None, nada. We're ready to spin and we're off the National Electrical Grid here and with a battery powered Scott Nixon DACkit, and this concept makes me happy. The need for complex power conditioning is naught.... Music arises from a completely black background. This only serves to enhance the now well known ability of Tripath amps to "unbundle" individual instruments from even dense mixes.

Warm midrange typical of Tripath sonic signature, as is bass control even at very low volume. Strident, etched highs more often noticeable with string and piano sounds, which contain complex harmonics in the upper-register. This is due almost entirely to the fresh, as yet un-worked chip, and it is exactly what I expected. It has been well established over the last couple years that one should not really judge the Tripath sonic before the first THREE months, left on full time, so burn in will likely take longer here.

Out of the box, the VinnieR amp completely eclipses the ability of the batter power Sonic Impact; I really didn't expect it, but this is an entirely different beast, with tons more speaker control, and just alot of sound coming from this little box.

Nothing Accesses Current Like A Bunny:

The optimized amp with battery power makes an already fast amp even faster, and was commented on by the kids as well. Attack transients were often startling. --Absolutely superb speaker control. I played it loudly for six hours on Saturday, and it recharged in under 20 minutes. Such is the nature of highly efficient digital amps. This one keeps going and going and...

Flea Amp?

Depends on your speakers. Using drivers with real world sensitivity, over 90db in my book, this approach might be all the amp some of us would ever need. Using outstanding drivers like the Fostex FE207E, (96db) and the Radian coaxial 502/B (97db) the bat-T-ery amp has more than enough juice to drive even the most hardened headbanger howling from the room. I know, because I did just that to a real headbanger on Saturday. The crossover-less Fostex, though far from broken in its supposed mandatory minimum 100 hours, sounded best, exhibiting better synergy to my ears, than even the Radians. So far sooo good.

D:
      Having four of the things (and a modded XR50) I've been messing about with changes to the basic thingy, also. Two are in development, one powered internally, one using a SLA batt. Encouraging news.

Regards,
Larry Welsh

The unit came in a natty black powder-coated aluminum case, with machined aluminum volume control and spiffy blue LED  ...

Just for clarification, the enclosure is black-anodize aluminum, not powder-coated.  

Dan, thanks for sharing your initial impressions!

Dang Vinnie, this is one great idea you have here!

It is a really slick looking tiny box now...love the way you shoehorned the 3 amp SLA in there.  The 13.8/13.2 v SLA battery was a major upgrade in my stock Sonic Impact over electric or, NimH (as these little cells floated to only 9.6 volts quickly during full operation, starving the SI of a precious couple watts)

DigiD (Vinnie), with the Scott Nixon and the little Clari-T, you got the backbone of a pretty impressive boom box now (or Executive desktop system).  Don't you both need more little projects?  

D, did you pair the Clari-T with your now de-nuded Vandy's?

Most excellent, Dr. Digi!!!  

D,

Sounds like you are hearing a lot of the same things I hear in my battery-powered Tripath. The dynamics are the most surprising thing. I remember reading somewhere that batteries are really good at dumping current in a hurry. That is what it sounds like at any rate.

I glad to see more options becoming available for these amps. They rock WAY beyond their means with higheff speakers.

D,

Sounds like you are hearing a lot of the same things I hear in my battery-powered Tripath. The dynamics are the most surprising thing. I remember reading somewhere that batteries are really good at dumping current in a hurry. That is what it sounds like at any rate.

I glad to see more options becoming available for these amps. They rock WAY beyond their means with higheff speakers.

Greg (and everyone interested),

The Clari-T-Amp has stunning transient attack and dynamics, and this is primarily the result of me wiring the 12V battery line DIRECTLY to the power input pin of the TA2024 chip (using a short run of 18gauge solid copper wire).  This provides the most direct power path to the chip, reducing noise as well as the series resistance and inductance contained in the stock Sonic Impact's small power traces that travel from the DC jack and across the board to the TA2024.    

SLA batteries generally have a very low built in series resistance, and they can supply a lot of current very quickly.  

I did not stop there  

I also increase power supply capacitance by 10X the Sonic Impact value using low ESR Panasonic FC capacitors, which are also bypassed by tiny  surface mount caps.  I actually do some really delicate surface mount soldering with the positive leads of the electroylic caps to the trace going straight to the power pins of the TA2024.  This, along with the battery line connected directly to the power input pins, results in a VERY FAST and dynamic sound, along with improved bass response, control ("tightness"), and tone.  

There are more surface mount "tricks" that I do to the amp board (which I plan to mention in a more formal product description that I am trying to find the time to finish).  This is not just a Sonic Impact board mounted in a nicer enclosure   .  This is all carefully thought out, tested, labor intensive work that I found needs to be done to take the performance level up...way up!  

Regards,

Vinnie

Hmmm...wonder how'd they'd work with the Daedalus DA-1s.  They're 96dB, but they're 6 ohm.  

What's the minimum ohm rating recommended for these amps?

DU

Have you thought about doing a audition road show, Vinnie?  

For those who have reasonably efficient speakers, and especially those who use the ack dAck! as well (like me), I think it'd be interesting to compare the amps with what we're currently using...not to mention being a great way to spread the word about your product(s).

Just a thought...

DU

All,

As promised, below are some more details about the Clari-T-Amp.  I still need to write a few paragraphs about the sound, but I also want others to post their findings when these are sold.  I should also work on a Q & A section as well.

As you will read, there is more to the Clari-T-Amp than meets the eye   (see http://photos.yahoo.com/vinnie822 for some preliminary photos).

Here goes:


PRODUCT DESCRIPTION

The Clari-T-Amp is a battery powered Class-T high-fidelity stereo amplifier.  Inside its portable-sized (4 x 6 x 2.5 inch) sleek black-anodized aluminum enclosure houses a highly modified version of the Sonic Impact T-Amp’s circuit board, along with a 12V Sealed Lead Acid (SLA) battery, and a “shunt-mode” passive volume control.  

DESIGN GOAL

The main design goal of the Clari-T-Amp is to significantly improve upon both the sound and build quality of the Sonic Impact T-Amp, while maintaining its small size and simplicity.

COMPONENTS

AMPLIFIER BOARD

The small surface-mount technology (SMT) amplifier board in the Clari-T-Amp is a highly modified version of the one used in the Sonic Impact T-Amp.

Modifications include:

a) 12V supply wire is soldered directly to the input power pins of the TA2024 chip with a short run of 18 gauge solid-copper wire.  This provides the most direct power path to the chip, reducing noise as well as the series resistance and inductance contained in the small power traces that travel from the DC jack and across the board to the TA2024.    

b) Power supply decoupling capacitance is increased by 10X the stock value using two low ESR 16V, 1,500uF Panasonic FC capacitors bypassed with 0.1uF surface mount caps.  The positive leads of the capacitors are soldered directly onto the exposed power trace (surface-mount style) that attaches to the input power pins of the TA2024.  Bass performance is substantially increased, while power supply droop is decreased.

c) Surface mount gain resistors are changed to reduce the amplifier gain to approximately the ideal value of 12V/V (per the TA2024 datasheet).  This reduces noise and distortion and allows for a more usable range of the volume control.

d) Input signal path is substantially shortened and cleaned up.   Here’s how:

In the stock board, the input signal travels a long path from the stereo mini-jack to signal traces that travel over the length of the board, adding L, R, and C elements and noise to the input signal.  It then passes through a connector and cable into another connector on the stock potentiometer board.  Finally, it travels back out the connector on the potentiometer board and into the other end of the connector on the amplifier board.  Needless to say, this long path is not “short and sweet.”    

The Clari-T-Amp sends the input signal directly to the input terminals of the shunt-mode pot, and then it is sent out directly to the amp board.  Excess trace length and cheap cable connectors are completely bypass.  Signal wire is upgraded to 24ga solid copper wire.  

e) Surface mount input load resistors to GND are removed

f) Surface mount series input inductors are removed and replaced with solid copper

g) Four Schottky diodes are soldered to the speaker output pins.  These are used to minimize undershoot of the outputs with respect to the power GND during switching transitions of the TA2024’s output FETs.  

h) Speaker wire to binding posts is beefed up to 18 gauge solid copper wire

i) Stock LED on board is removed


BUILT-IN VOLUME CONTROL

The Clari-T-Amp contains a built in passive “shunt-mode” potentiometer to control the volume.  In this configuration, only one resistor is actually in the signal path.  The potentiometer is simply used to shunt a portion of the signal to ground (which varies with knob position).  


BATTERY POWERED

The enclosure houses a 12V, 1.3Ah SLA (Sealed Lead-Acid) battery.  This battery has the advantages of a noise-free high-current output, small size (portability), and simplicity over an ac/dc power supply.  It also costs much less than a high quality linear-regulated ac/dc power supply found in most amplifiers.  You no longer will even need to be concerned with power conditioners and power cords.  


BATTERY CHARGER

The Clari-T-Amp comes with an Automatic Charger for the 12V SLA battery.  When the charger is plugged into the Clari-T-Amp jack, a red LED on the charger indicates that charging is taking place.  At the end of the charge cycle, a green LED on the charger indicates the battery is fully charged and is being maintained.


REAR PLATE INPUTS AND OUTPUTS

One L/R pair of high quality, ruggedly built and gold plated RCA jacks (to withstand abuse and oxidation) for the low-level input.

One L/R pair of speaker binding posts that will accommodate either a standard dual banana plug, up to 16 gauge bare wire, or high current spade connectors stacked up to 5mm high.

One ON/CHARGE mini toggle switch (when the battery charger plug is not connected, it is essentially an ON/OFF switch).

One DC jack for the SLA battery charger plug.


FRONT PANEL

One center-mounted anodized aluminum volume knob

One blue LED that is illuminated when the amp is switched ON.  


ENCLOSURE

The enclosure is a solidly built, black-anodized extruded aluminum enclosure measuring only 4” wide x 6” deep x 2.5” tall.  It was chosen for its small size, solid construction, smooth looking appearance, and noise shielding properties.



Thank your for your interest (and patience in reading this   )

As always, feel free to email me with any questions.  I will try to respond promptly during the evenings...

-Vinnie