Class T-amps

[leo]

I'd still stick a cap across the resistors on the adjust pin of the onboard regulator.
Its a supply for the audio controller and the input bias so best to keep it clean

[leo]

Just seen a post on diyaudio pointing to a TA 2022 board on ebay with a built-in valve input stage for 79 Dollars delivered.Looks interesting.I can't post the link as I'm on my phone.

This one?

http://cgi.ebay.co.uk/New-Enthusiast...item1c11bd1026



And some other variations

http://cgi.ebay.co.uk/TRIPATH-digita...item483a617ce3

http://cgi.ebay.co.uk/90W-90W-TA2022...item2eaca786ed

[Ali Tait]

Yes thanks Leo.Reason I pointed to that is because this Hlly amp uses the same chip,and while on it's own the amp is good,used with my WAD Pre 2 it is excellent,so this board with a valve input stage might be very good.

[leo]

No probs Ali, I'm even more confused which to try now
Certainly no shortage of options with these Tripath amps, I've already got a pair of Hypex UCD's but still very tempted to try one of these Tripath's to fiddle with

[Ali Tait]

Well I like this TA 2022 chip.Sounds very valve-like to me,with very deep and tight bass.Have you tried the Hypex units? What do you think?

[AndrewR]

I have just ordered one of these Andrew so I will be watching your posts wth interest. The only doubt I had about this board was the fan as I sit close to the hifi and was worried about noise so I am pleased that it can be replaced with a passive heatsink. Where did you get it from?

Hi Covenant.

It is a Zalman ZM-NB47J (effectively a cooler for the Northbridge chip on a motherboard), can be had for £5.75 on Amazon.

If you are feeling brave enough, try replacing the inductors (Wuerth 4.7uH XXL types about 9A if I remember correctly. Available at Farnell) when you have removed the inductor. It was easier than I thought it would be. Here are my tips for doing that:

a) I used a relatively cheap, but temperature controlled iron
b) I removed the heatsink before replacing them, giving better soldering access.
c) I took on Sendler's advice about heating one side of the inductor (until the solder liquefies) and prizing it up with a small flat bladed screw driver
d) After prizing it up, completed the extraction by holding the top of the inductor with a pair of long nose pliers, heating the other side until it liquefies and it should easily pull off.
e) Tinned the new inductor solder pads
f) Tinned the board solder pads
g) Soldered while making sure the solder liquefies. May take a couple of goes
h) Measured the resistance between the pads

Page 139 of the diyaudio.com thread also shows a good diagram (you need to be logged in to see it) detailing how to improve the input stage.

Andrew

[dave2010]

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

This is a complete board based around the tk2050 tripath chip - output up to 100 watts into 4 ohms.

I'm not electronically savvy, but even I could plug in a laptop power supply for this to work. And work it does. I'm currently using it on a computer sourced set up with a Benchmark Dac1, then this board powering Castle Isis speakers. I love the sound. For £27 it is a 'no brainer' for anyone wanting to explore tripath chips. With no mods at all, it is a very classy sounding amplifier.

I've had the Sonic Impact, still got Trends Audio TA10 and the Teac Al700p and also use a winsome labs mouse. So, I've been a keen follower of this technology and sound. The Sure Electronics IMO is brilliant for the money. Typical of the tripath sound, it has a very clean and sweet top end. The bass goes down well, but lacks some articulation. But the mid range is wonderful, a little forward but brimming with detail. It is a more full bodied sound, compared to my leaner sounding Winsome Labs mouse.

I'm sure that improvements could be made on the power supply I'm using, but, in all honesty, for an office hifi setup, the sound is so musical, that I can't be bothered tweaking it further. It's also a setup that makes nonsense of the formulaic approach to system building ie spend 1/? of your budget on source, 1/? on amp and 1/? on speakers. The original sonic impact was startling for £20 to £30. The sure electronics amp board is much better IMO.

Just missed a Sonic Impact on eBay UK yesterday. Maybe though, not worth going that way if the board you mention is so much better, though doesn't it require just a little extra expertise - e.g to fit a volume control, and maybe put it in a box? Perhaps it could be kept out of the box as a work of art - perhaps on a board with some perspex above it. Not sure how well that'd go down.

Are the really cheap ones you see on eBay no good at all, or would I get a feel for these Tripath things if I bought one? There are even some (Lepai) ones for under £20, and there are loads for about £20 plus around £10 shipping - though not sure how reliable ordering from China is. I really would just like to hear one first, and then decide how much to spend. Are there any Tripath designs sold in regular hi-fi shops by well known makes (e.g embodied in currently available amps costing betwen £80-£500), in which case I could maybe arrange an audition? Buying a more expensive one, such as the HLLY 90 or a Bantam or making up one as suggested are all options, but I've still no idea what I'd be buying into. That's why I wanted to bid on the Sonic Impluse as I figured I could flog it on again if I didn't like it.

I'm still somewhat intrigued by the technology. The patents on the chips suggest that the design doesn't just use simple Class D techniques. For a start, PWM is I think replaced by PDM (Pulse Density Modulation), but it has occurred to me that there could be multiple digital signal paths in the chip, and slightly more complex switching at the power end than a really simple design would suggest. Also I need to swat up even on Class D further, as I don't know if they operate in positive and negative going directions, or simply with one polarity and then a DC offset adjustment (which could be a pain, as it might be signal dependent). There could be some quite ingenious techniques used to make these things work and deliver the higher quality claimed in these T-amp variants.

[Ali Tait]

Leo,found this on ebay-

http://cgi.ebay.co.uk/ws/eBayISAPI.d...#ht_6321wt_960

Could be used with any tripath amp.

[dave2010]

Also I need to swat up even on Class D further, as I don't know if they operate in positive and negative going directions, or simply with one polarity and then a DC offset adjustment (which could be a pain, as it might be signal dependent).

Not only that, but I discovered I didn't really know how switching power supplies work. I've since found out more and even about buck and boost circuits, and this poster might help a bit - http://focus.ti.com/lit/sg/sluw001d/sluw001d.pdf There's a lot more to power supply design than I'd thought, and rather a lot of design variants.

When I stopped to think about it, I was surprised to think that the rather small mobile phone chargers work using this kind of technology - see http://en.wikipedia.org/wiki/Switched-mode_power_supply Maybe I'll dismantle a spare one to see what's inside!

Here is another fairly detailed web site - http://www.hardwaresecrets.com/article/327

The pages at How Stuff Works are I think, rather simpler and don't really go into much detail.

[dave2010]

This one?

http://cgi.ebay.co.uk/New-Enthusiast...item1c11bd1026

From the website -

10.The board have debuggered to the best state, and re-check before shipping, please rest assured to use.

Funny things these people get up to!