My Class D PWM amp project.

[stroy05]

I am currently awaiting the arrival of a module and power section. Would it be possible to add a preamp and EQ with this unit?

I am going to be using this as a bass guitar amp and I would like to add some EQ and a preamp inside the casing. What is the easiest way to do this.

This is my first real project with amplifiers. I went with this because of the plug and play factor. If any of you can help me out that would be great.

[TNT]

Originally posted by ericpeters
I just replaced the 55V / 500VA transformer with a 42V / 1000VA transformer and the difference is amazing.

Even at very low volume there is a substantial difference in bass, treble and also soundstage.

Adding some bass because of a bigger transformer is understandable, but I can hardly beleive that this also improves the treble and soundstage.

I still get the amp to clip (altough at very loud level) so I think a further enlargment of the entire power supply will not do any harm.

Yepp!

When I changed the 400 VA traf to a 1400 VA I had the exact same experiance. Improvement also on low levels :-)

/

[Joep Zonnebloem]

Roy05: It looks like we have exactly the same target. I am going to try the ZAP for bass guitar as well. I will try it with my Trace Elliot GP11 equalizer or the preamp section of my SWR redhead. I also want to try it with the Line6 Bass Pod XT, but I haven't bought one yet (after all, you easily forget that it's going to cost a considerable amount of mony altogether...). With the Bass Pod, you will probably have the digitallest of bass tops that you can imagine http://www.diyaudio.com/forums/images/icons/icon6.gif
Cool
Please post your findings, as I will by the time I get to it. Succes!

[stroy05]

Glad to hear there are others out there trying to figure out the same thing. I have built the amp section. It sounds very good. Clean and clear, able to hear every movement of my hands. The good and bad.

I am in the process of designing a preamp section. The only problem is designing the power supply for it. Since I am using the preditor power supply I need to figure out how to split the wall source before the amp power.

IF there is anyone out there that can help me out with this that would be great. I need to be able to split the incoming power (from the wall) and send the split to the power amp section and the preamp section. I have a smps design that has outputs for a preamp and poweramp but the power section for the amp is to low of voltage. If anyone knows a way to up the voltage for the pweramp section please let me know.

[ericpeters]

Keep it completely separate, separating power supplies for different parts of audio equipment is one of the basic differents between midfi and hifi.

Use a different transformer, rectifier and capacitors.
For a power amp you need high current capacity. For a pre-amp you need a flitered power source with a litle noise as possible.

[stroy05]

I have no idea how to split the power coming in.
can someone show me how this is done.

[Joep Zonnebloem]

Hi stroy05,

As for the power amp:

I just ordered 2 zap modules and I intend to experiment with a huge power supply (~70 V, around 1500VA-2000VA, maybe more is wise?) and huge capacitors of around 100.000 mF (would more be wise?). And maybe see what bridging does. Maybe I'm just a fool..., we'll see.

What EricPeters says makes a lot of sense, IMHO; don't worry about splitting your power into discrete components: let the preamp have its own power supply.

I was glad to hear that you evenly liked the good and the bad things coming from your speakers when you play the bass. As long as the bad sound is coming from your hands, keep on trying to make it sound good; when it concerns the amp or the speakers, buy or build new ones.

That's what we are trying...

[stroy05]

I guess what I am trying to achieve is an amplifier and preamp in one single box. I would also like to get rid of the large transformer and find some kinda switching power supply for the preamp and poweramp.

[Joep Zonnebloem]

Originally posted by stroy05
I guess what I am trying to achieve is an amplifier and preamp in one single box. I would also like to get rid of the large transformer and find some kinda switching power supply for the preamp and poweramp.

Stroy,

Sorry for my inadequate reply (some long time ago). I assume you have figured out in the mean time how to split the mains?
As for the SMPS, you might have read the post in various forums (a.o. about ICpower for PA applications etc., ICE/ class d amps used for PA/musical instruments? ) ? I am interested in A and T labs power supply ( http://www.a-and-t-labs.com/K6_Sw_Amp/index.htm). There are some people who are testing it right now, so I want to read their findings first.

Regards, Joep

[ghemink]

Originally posted by Joep Zonnebloem


Stroy,

Sorry for my inadequate reply (some long time ago). I assume you have figured out in the mean time how to split the mains?
As for the SMPS, you might have read the post in various forums (a.o. about ICpower for PA applications etc., ICE/ class d amps used for PA/musical instruments? ) ? I am interested in A and T labs power supply ( http://www.a-and-t-labs.com/K6_Sw_Amp/index.htm). There are some people who are testing it right now, so I want to read their findings first.

Regards, Joep

I have ordered that SMPS, don`t have it yet. I would only use an SMPS with bridged amps since power supply pumping can be an issue because of the relatively small caps at the output of the amp (about 1000uF per rail). The regulation would also be screwed up (I expect) when you have power supply pumping as the A&T labs SMPS regulates the sum of the + and - rail and keeping that for example at 120V. If the + rail is pumped up, the - rail will be regulated down. At least that is what I expect when looking at the schematics. I assume the SMPS works best when both rails deliver the same current at the same time as with bridged amps.

Gertjan