LuFo Amp - 39w SE Class A from 28v Rail

[xrk971]

You could do 36Vpp or close to 20w rms into 8ohms.

 

[Ryssen]

If I make a "stereochassie" will a single 400VA/2x20v trafo be enough,if I run 3A/channel trough it?

 

[xrk971]

A 400VA trafo can run two channels at 3A just fine. I have confirmed this by running one at 6A.

 

[Vunce]

Hi Ryssen, if you want full power potential you’ll need 22v secondaries for use with a conventional CRC psu, and 24v secondaries if you plan on using a capMx type psu.

 

[xrk971]

We are making good progress on an OPA454 front end for the LuFo with built-in lower mezzanine +/-35v DCDC PSU. We have previously used this LT 8xxx SEPIC topology isolated DCDC converters in other projects. They are supremely quiet and switch at 2MHz, so easy to filter. JPS64 did a wonderful job on the layout. I’ll be ordering the prototype PCBs and building up a test unit to be used with the main amp PCBs.

These boards will double stack and mount where the daughter board is shown here on the main LuFo amp PCB.

 

[Ryssen]

Hi Ryssen, if you want full power potential you’ll need 22v secondaries for use with a conventional CRC psu, and 24v secondaries if you plan on using a capMx type psu.

OK

 

[TungstenAudio]

Interesting job with the mezzanine power supply. How do you separate the Vin from the Vout? Looks like the standoffs run straight through.

 

[xrk971]

The vout goes to 3pin header connecting the 2 boards. So the +v smd -v bolts are not connected on top board.

 

[TungstenAudio]

Clever, I missed the 3-pin header.

 

[poseidonsvoice]

Great work X and JPS!

Best,
Anand.

 

[xrk971]

A universal dual rail DCDC converter in M2X format can come in real handy for a lot of new front end designs.

 

[dBel84]

This is looking great. Evertime I promise to sit back enjoy the amps I have built, another pops up that is too tempting not to try!

.. dB

 

[xrk971]

Hi dB,
Thanks - this one is going to be a lot of fun. Do you have some MOTs handy?

 

[dBel84]

I soon will

 

[xrk971]

Hi folks, a big thank you to Vunce for making a Mouser shopping cart for the LuFo amp. Several items are optional so you can pick and choose if you want to use Molex Minifit connectors for mosfet flying leads. Or silver mica 22pF cap or SMT. If you get everything, it’s $86 for stereo pair. You still need to provide the MOT and the LU1014D and TO-247 PCB adapter from the GB. There may be some adjustments to this cart but it’s close. Please do not edit cart. Save to your own project first before editing.

Mouser Electronics

 

[xrk971]

I made some videos on how to assemble the LU1014D parts onto the IMS adapter boards here.

 

[xrk971]

The LuFo PCBs arrived. Nicely designed by JPS64 in mirror symmetry with 21,000 vias stitching the two sides together. These boards are huge and give plenty of space to work with - designed to be used with a standard UMS heatsink.

 

[dBel84]

boards are looking great , I like the way you have adapted this design to take the yarra daughter cards , might have a use for my ACP+ after all

 

[xrk971]

You could certainly use the ACP+ if you are willing to live with the lower output power. Other choices are Melbourne, which can be adapted to use +/-35v rails for full power.
Maybe someone knows if there is a way to get ACP+ to work on +55v supply to swing a full 50Vpp?

 

[zman01]

X,

PCBs are looking very nice - another superb effort by JP!

UMS heat-sink compatibility, low parts count, and spaced out layout of the PCB should make it very easy for DIYers to build this amp.

Many of the gang already have +/-24 V power supplies - what sort of output power can they expect from that?