K4003 Amplifier - How do I power it?

[myspacer00]

I have a Velleman K4003 30W stereo amplifier kit that requires 2x12VAC / 2A power supply.

Can anyone tell me very simply how to power this from mains?

I mean whats the simplest way? Would this work?

http://store.qkits.com/moreinfo.cfm/PS1220

Or if I HAD to use one of those internal transformers how would it all hook up?

Say I buy a 12V 50VA chassis mounting mains transformer. I wire that up to the PCB, then I can wire up a DC input jack so it looks like:

Amp PCB > Transformer > DC input jack

What type of mains plug would I use to feed into the DC input jack because they are all transformers anyway right?


Any help is appreciated! Pictures and links would be useful

[DigitalJunkie]

You need 2x 12Vac supplies. After rectification to DC this is ~16Vdc for each 'rail'. So,to run it from DC,you'll need (+16)-(0)-(-16) Vdc.

It would probably run fine at +/-12V,but with reduced power.

If you can find some 12VAC "power packs" like those,you can use two of them.

The best option might be to get a standard 2x 12Vac/2A power transformer,and put it all in a case.

[myspacer00]

Yes, ok. So I have to buy a transformer but then I still don't know what type of mains cable to hook up to it.

As I said before it will look like:

Amp PCB > Transformer > DC input jack > DC output jack mains cable.

Again, what type of mains plug would I use to feed into the DC input jack because they are all transformers anyway right?

[cpemma]

Originally posted by myspacer00
Yes, ok. So I have to buy a transformer but then I still don't know what type of mains cable to hook up to it.

As I said before it will look like:

Amp PCB > Transformer > DC input jack > DC output jack mains cable.

Again, what type of mains plug would I use to feed into the DC input jack because they are all transformers anyway right?

You seem to have a hazy grasp of the power side, which is dangerous. The usual system is,

230V AC mains ->Transformer ->Rectifier & Smoothing -> Amplifier

With the K4003 kit, rectifier and smoothing are on the amp PCB, so you'll be needing a dual (0-12, 0-12) secondary or centre-tap 12-0-12) secondary transformer, and taking the appropriate three wires to the amp PCB. The transformer must be fitted in a ventilated case away from fingers, with 3-core 5A mains cable, L & N to the transformer primary, cable earth wire to the case, 13A plug (with 2A fuse) on the other end. A switch can be fitted to the case along with the other audio connectors if the amp PCB is to be in the same case.

The "illustrated English manual" clearly shows how to connect either type of transformer. Read, seek live help closer to home if you don't understand it. Rapid Electronics sell a suitable transformer, the 12V+12V 50VA, and various cases you could mount everything in.

You could probably create the required split-rail DC supply with two 12VDC adaptors, but that's in lesson #2.

Mains -> DC adaptors are not transformers, though they may contain one.

[myspacer00]

I have now done my reading. I have done a lot of soldering and such but have never had to deal with anything other than basic 9v or 12v battery power.

I have bought a suitable transformer and I have fully assembled the amplifier.

I am now looking for a set of decent component speakers to go with my project.

Any advice on what type to get? I was thinking of just salvaging some from some car boot sale purchases but the quality may be a bit of a gamble. I would rather buy new.

Any advice?

Thanks.

PS: I am constructing a stereo speaker box out of probably black walnut, which will house all the gubbins. Basic idea is something around the size of a large DAB radio (probably bigger) with a simple line in for an MP3 player. All schematics have been drawn up.

If I was to house the transformer inside the speaker box how would I attain the proper ventilation?

[AndrewT]

Originally posted by myspacer00
I have now done my reading..........................If I was to house the transformer inside the speaker box how would I attain the proper ventilation?

if the speaker is sealed loading then no ventilation.
If you go for a driver that needs vented loading then you have only one vent (generally) and this does not ventilate well.
What you need is a two compartment box. One dedicated to the drivers and their loading requirements
The other dedicated to the amplifier and it's cooling requirements.

BTW,
50VA is a bit small for a 30+30W stereo amplifier.
A good value for performance spec would be VA=1.5 times total maximum output power, i.e.100VA.

[cpemma]

Originally posted by AndrewT
BTW,
50VA is a bit small for a 30+30W stereo amplifier.

The 60W includes about 35W of sales hype.

The Velleman K4003 2 x 30W Audio Power Amplifier electronic kit is small amplifier constructed with the TDA2616 IC, with a maximum supply capability of 2 x 15Wrms (4 ohm) of 2 x 10Wrms (8 ohm).

"# music power output: 2 x 30W / 4ohm"

http://www.quasarelectronics.com/vk4003.htm

[AndrewT]

Oh, I see now, it's a 10W + 10W amplifier.
The minimum transformer required about 30VA, so 50VA is adequate.

[myspacer00]

Yes the manual said that 50VA was recommended. So maybe I should buy a project box from maplins to house the transformer.

As you can tell im a complete newb when it comes it audio based electronics. I am still a bit confused as to what type of component speakers would be best for this amp.

If someone could link me to 1 or 2 examples of suitable speakers that would give me something to go off.

Any help is greatly appreciated!

[cpemma]

Originally posted by myspacer00
As you can tell im a complete newb when it comes it audio based electronics. I am still a bit confused as to what type of component speakers would be best for this amp.

If someone could link me to 1 or 2 examples of suitable speakers that would give me something to go off.

It's a tricky one as the amplifier will drive virtually any 4R-8R speaker system (bearing in mind it's only low wattage and modest quality, there's no point in going too upmarket), so it comes down to what you want to pay and design skills.

Years ago I took a similar amp to work along with an old cassette deck and an old pair of hi-fi speakers and ran it in the office at lunch-time, very nice too in a small room. I suggest looking round for S/H domestic speakers to suit, it's difficult to compete on price and quality building your own at the budget end.

There's a similar thread in the Chipamp forum ATM, have a look.