First time Class D-IYer

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alexmoose

alexmoose

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Joined 2006
#1
please excuse the terrible pun.

Hello everyone, I am looking to build a simple class D amplifier, because I love the concept (and my RA keeps bugging me to build one). The only problem is that I have never worked on any real digital circuitry before (only tubes, and other analoge stuff). Is there a schematic that is simple, and fun for a first timer? I don't need much power, 5-15 WPC should be just fine.

Thanks alot
-Moose
 
#3
Niico gave you a good site to check out. You should check out the Amp6 Basic. There are reviews on this site on that particular amp you can check out (from me and from others). They are somewhere under the Class D forums, maybe on the 2nd, 3rd or 4th page, but no later than that.

It is the most beginner friendly amp to build. And since you are in school you can probably get an electrial engineering student to check your work or have them with you when you solder to ensure you got everything correct. You should also be able to borrow a multimeter from them too. Also, the instructions are the easiest to follow too, since there are pictures to guide you. Other amps don't have that.

I have pics of a finished Amp 6 Basic posted here

http://s101.photobucket.com/albums/m59/Xspunge/?

Let us know what questions you have and someone will be able to help you out.
 
#5
Amp9 is also a very easy build, like amp6 also with trough-hole components mainly... Amp9 has the chip I listen to every day with much enjoyment :bigeyes:

A bit more power can't hurt? 😎

And the chip is quite fool-proof, protected against all kinds of abuse..:angel:

Supply is within the range of a single 10 to 27 Vdc, but this amp allready rocks at 12 Vdc!
 
#6
I was thinking and almost positive I going to make Amp5. I looked at amp 9, but was dis-enchanted when I saw it is designed for a 4 ohm load, has anyone run it with an 8-ohm load? do you still seggest the amp9 for my 8-ohm speakers?
 
#7
It should work well with 8 Ohms load.

But if you want to tune it for 8 Ohms, you could change the output caps values and the toroid values.

I don't know the amp9, but usually it is replacing .22uF caps by .47uF caps and the toroid should be around 15mH.
 
#11
I wouldn't worry about 8 ohm loads, all it can result in is a bit less power, but since it has plenty i would change nothing and just enjoy it. (a 4 ohm capable amp can drive tougher loads and will keep up the compatibility of the amp...)🙂 🙂
 
#13
alright, sounds good! now for a far simpler question!

does anyone seggest a good power transformer for this amplifier (Preferably a torodial)? because I have found one with a 25v secondary, rated at 300VA, it has the right current, but it would require unwinding quite a few wires off the transformer to make it suitable. does anyone seggest a transformer? (in a decent price range, the 25v 300VA is 19.95)
 
#15
alexmoose said:
I was thinking and almost positive I going to make Amp5. I looked at amp 9, but was dis-enchanted when I saw it is designed for a 4 ohm load, has anyone run it with an 8-ohm load? do you still seggest the amp9 for my 8-ohm speakers?
Click to expand...

Just finished a amp5 and using it to drive 8ohm speakers. Sounds very good and goes louder than I need. Easy to build as well.
 
#16
niiico said:
I may be wrong, but...

25 V AC secondary means 25x1.41=35.25 V DC at least.

And this is far beyond specs. (33V is the maximum voltage before damaging the amp)

To get a 24V DC you must find a transformer with 18V AC output.
Click to expand...

I know, you're right, which is why I would have to resort to unwinding part of the Transformer, but if anyone had a good one in mind I am open to seggestions

Heady,

how does the high-range of Amp5 hold up? it looks like the distortion kinda looses it above 5k, does it sound really nice in the high range?
 
#18
I don't think this solution can be rendered as very "audiophile" though...:whazzat:

This link shows that the chip can handle an absolute maximum of 40Vdc:
http://www.tripath.com/downloads/TA2022.pdf

Maybe the best way to go is indeed unwinding the secondary on the tranny...

Or maybe there's the possibility you can upgrade a few components to be able to handle it, but beware, the chip/amp/parts can have a very short lifespan this way... :bawling:
 
#19
I think the best chance is to add ADDITIONAL windings to the transformer secondary in the reverse direction, then nothing would be lost powerwise. I think I would need to add about 70 windings in the oppisite direction to lower the secondary from 28v tro 18v with, the transformer has a power rating of 500VA, so at 19.95, its a really good deal
 
#20
alexmoose said:

Heady,

how does the high-range of Amp5 hold up? it looks like the distortion kinda looses it above 5k, does it sound really nice in the high range?
Click to expand...

When I first built the amp, I used the supplied electrolytics for the input caps. The treble was horrible, very artificial and screechy.

I then substituted them for a pair of Solens polypropylene caps which was by-passed with Vishay-Roedenstein caps and the high end really cleaned up. Now with the burn-in, the high end sounds very tame, maybe a little too tame but that could be due to my other equipment.

You can see the pics of the mods I made in this link:
http://www.41hz.com/Forums/topic.asp?TOPIC_ID=742
 
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