Zen 9 Power Supply

[vdi_nenna]

Hi All,

I searched and used references, but didn't find an answer for my power supply question. The results always seem to be half answered!

How do I make a power supply like the one pictured with 1 transformer?
6moons audio reviews: FirstWatt F3

To get 36v an 18v-0-18v-0 transfo needs to be wired in series. See attached.

How is it done in parallel like in the 6moons site photo? Do I need a 36v-0-36v-0 transfo?

Thanks,

Vince

[dave_gerecke]

Hello Vince, by parallel, I am guessing you mean having a separate secondary for each channel. If this is what you mean, then yes, you would need a transformer with two 36 volt secondaries, instead of two 18 volt secondaries. This is assuming you want a secondary for each channel of the amp. You could also go really crazy and have a separate transformer for each channel, thus the only shared components of the amp are the enclosure, power input cable/socket and power switch.

Keep in mind though, the 18 or 36 volts you refer too are AC. Once they are rectified and filtered, the DC voltage will be the AC voltage times the square root of two (minus the voltage drop across the diodes in the bridge)

Peace,

Dave

[vdi_nenna]

Thanks Dave,

It just seemed that somehow everyone was using a split 18v secondary transfo to feed each channel 50v. So that's not the case. I need a 36v-0-36v-0 transformer.

Regarding enclosures in general- It is tempting to build a 4 chassis power amp. Always wanted to do multi-chassis config, but with all due respect, would this circuit design benefit from such an effort? I ask this mainly from the stand point of power output.
Aside from channel seperation, cooling and grounding benefits, do you think there would be a sonic improvement?

Regards,

Vince

[dave_gerecke]

Hey Vince, putting two 18 VAC secondaries in series, then rectifying and filtering will give you approx 50 VDC, so that is one way to do it. However, with a single transformer, you are either going to have both channels running off of one power supply, or you will need a transformer with four 18 VAC secondaries. Either way, the transformer needs to have twice the current capability than for a single channel. The only other way is as I previously described, using one transformer for each channel. If a proper chassis is chosen, this would be possible.

Doing a design where each amp is in a separate case is another option. Even the four case design is an option. As to the improvement in sonics, I can't speak to that, as I haven't built the particular amp (yet) or tried doing a four case design. However the law of diminishing returns starts to come into play here. The only real advantage to having the PS in one case and the amp in another would be room for a bigger transformer and more capacitance. Since this is a Class A constant current design, a bigger transformer isn't really necessary. And more capacitance is nice, but at some point it becomes superflous. Of course, this being diyaudio, going overboard in a design is allowed, even encouraged!

Peace,

Dave

[vdi_nenna]

However the law of diminishing returns starts to come into play here.

That's what I thought, but I didn't consider that the CCS is already part of the PCB. Granted, the transformer and caps benefit from being placed in another case, but I consider the CCS as part of the PS also. The CCS probably has to stay close to the amp circuit for a variety of reason.

Either way, the transformer needs to have twice the current capability than for a single channel.

A 36v 400va to 600va would probably cover it.

Thanks,

Vince