Sure 50watt Cass-D Mini-amp

I just got one of these to see how the TDA7294 chip it is based on performs and I have to say I'm really impressed by the quality of item you get for £28 delivered!

The case is aluminium extrusion with a thick solid aluminium face plate. Vol knob is metal too and it has binding posts on the back not cheap clips as one finds on the original 'T-amp'.

Whats-more the PSU is nicely overrated at 120watts! Since the amp IC is rated 50watts at 10% THD it is more realistically a 30watt amp for proper hi-fi use. So the PSU is rated double.

Inside the case there is extensive filtering for the power lines and a digitally controlled analog volume control IC (not a plain potentiometer). The amp IC is heatsinked with a plate of aluminium and faces to the bottom of the extruded case and it looks as though they are meant to touch but they didn't use a thick enough piece of metal. So I stuck a few craft-knife blades stacked together in the gap to flesh it out and get the whole case acting as heatsink.

 

Looks great.
Wonder how many confuse it with that other 'Shure'

 

Any chance of a link to the supplier please?

 

I bought mine here - http://www.ebay.co.uk/itm/2-X-50Watt-Class-D-Audio-Amplifier-TDA7492-19V-adapter-/111140230182?

There are other brands too, I just searched ebay for TDA7492.

 

How does this Sure amp fair in a listening test against (say) a Quad 303 or other low power quality amp?

 

I've not compared using high quality speakers against a known good amp. I'd like to when I get the chance.

It should sound good, the distortion is low, here is a plot of 1KHz disto vs. output power on a 25V supply. If there is an achilles heel it is the distortion around 3-6KHz which is higher than the rest of the range (something to do with multiples of the PWM freq I wonder) peaking around 0.2% within sensible power outputs. Whether this adds a slight sound will depend on what sort of harmonic content it is. I'd like to find out. It's certainly not going to sound 'bad' though!


how to capture screen

 

That's a sightly odd plot (the manufacturer's?); flat up to c.20w is deeply unlikely. And what's the bandwidth of the THD measurement..?

 

You can see the datasheet here - http://www.st.com/web/catalog/sense_power/FM125/CL1503/SC983/PF214773

I've noticed many amps have quite a flat THD vs power response at 1KHz. At 100Hz or maybe 20KHz things are a little more variable with power.