Wiring transformer to AMP-32 PS

[nguoiduc]

Hi there,

I recently ordered an AMP-32 PS kit. While checking out the assembly manual I saw that it only has one rectifier bridge, but the transformer I have has dual secondaries. I want to use this one Amplimo 80VA 2x9V

My question is, when I parallel the secondaries I get nearly 9A of current. Would that be a problem for this amp? Or would there be an alternative way of wiring a dual secondary transformer to the AMP-32 PS?

Help is much appreciated!

[V-bro]

That'll be fine mate, nothing bad will happen from a little extra reserve current except when the amplifier is defective in the first place off course as there will be enough force to push through to kill it. Once confirmed the amplifier works it is fine to apply any amount of current power supply...

[gnome]

The problem though it that at 9V you'll not come close to what it is capable of, you'll be getting horrible distortion with just 0.5A and you can't place the outputs in series because the amp32-PS max voltage is 14.7V (I'm actually not even sure it will work that low?)

Why did you get the Amp32-PS? I t is an amazing little amp for sure, the amount of oompf it has is pretty incredible, but the big benefit is it's diminutive size if you're going to box it up with a transformer that benefit really goes out the door, and you should have gone for an Amp6 which does actually sound better.
Oh and have you done SMD soldering before?

[nguoiduc]

Well, I got the AMP-32 because it's going inside of a kitchen boombox, so I was looking for the cheapest option. No need for that extra sound quality of the AMP6 though.

Yeah, I've done SMD soldering before (did a GrubDAC recently), so that shouldn't be a problem.

Thanks for your quick help, guys! So, I guess I get something like this for testing purposes and connect the paralleled tranny later?

[V-bro]

No no no, it will work as 9Vac will be roughly 9x1.41=12.69Vdc after the rectifier bridge...

[gnome]

Oops sorry about the wrong advice

[V-bro]

Oops sorry about the wrong advice

A mistake I still commonly make too, it is confusing as many feed the -PS amplifiers with an SMPS with DC out and then the x1.41 rise is not there...

[nguoiduc]

Maybe you can help again a little. I found another option to wire it, but am quite uncertain about it. I found out you can also take two of the secondary wires and create a center tap. Wiring is the same as running the secondaries in serial, but you'd connect this newly created center tap to ground.

30278_10mg.jpg

Now I'm not really sure: Will the voltage double as in serial mode or will I get my 9vac? I just did an experimental hook up of my tranny, but somehow my multimeter was giving me a hard time today and I couldn't messure it myself.

[V-bro]

You are confusing two things, the method you describe is only needed for single ended amplifiers that need a symmetric power supply voltage, here we are talking a bridged amp, AMP32 which can run on a single supply voltage. If you run the center tap and the transformer has two 9Vac windings it'll become 9-0-9, which is a zero point and 18Vac...

You need to parallel, not series connect the two windings...

[nguoiduc]

Ok, thanks for making this clear!