Pizza Box v2.0 Class D amp project

[HAL]

Wanted to try out the Orchard Audio Starkrimson Ultra Class D amp modules and decided to purchase a pair of DIY modules from Leo.

Decided to try out a different SMPS DC power supply, so purchased a pair of Mean Well SMPS for 36VDC @13.8A PFC version units to stack for the +/-36VDC power supply requirement.  This version SMPS has an aluminum case for cooling and shielding.  Yes, this does mean the total SMPS is capable of 1000W power to the amp modules.  This will probably need a soft start circuit added eventually.

I am terrible at making chassis for projects, so picked up some 16in pizza boxes for the temporary housing.  Used something similar for the LM3886 Chip Amp project awhile ago, but these are better built boxes.  The SMPS are actually lighter than the toroidal transformers I used for the earlier amp linear power supply.

Testing the SMPS first to make sure stacking is not a problem with small load resistors before connection to the DIY amp modules. 

[Nick B]

Interesting project, Rich. I really enjoy my Ultra. Will it be necessary to shield the power supplies from the main boards to get better performance?

Nick

[HAL]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis. 

[Nick B]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis.

Rich,

I like the idea of separating/isolating the power supplies. Have you ever used vibration control devices to see if you squeeze max performance out of a device? Years ago, Steve McCormack told me he was using small still points within the chassis and it improved the sound. I didn’t ask what the exact implementation was.

Nick

[HAL]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis.

Rich,

I like the idea of separating/isolating the power supplies. Have you ever used vibration control devices to see if you squeeze max performance out of a device? Years ago, Steve McCormack told me he was using small still points within the chassis and it improved the sound. I didn’t ask what the exact implementation was.

Nick

Nick,
I have used feet made with Navcom and Sorbothane on electronics for vibration damping.  This helps isolate any mechanical noise going either way.  I use hard points to couple speakers to the floor for stability and not moving, so the opposite of damping.  If the speaker cabinet moves with vibration not a good thing.

Just my way of thinking.

[GDHAL]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis.

Rich,

I like the idea of separating/isolating the power supplies. Have you ever used vibration control devices to see if you squeeze max performance out of a device? Years ago, Steve McCormack told me he was using small still points within the chassis and it improved the sound. I didn’t ask what the exact implementation was.

Nick

Nick,
I have used feet made with Navcom and Sorbothane on electronics for vibration damping.  This helps isolate any mechanical noise going either way.  I use hard points to couple speakers to the floor for stability and not moving, so the opposite of damping.  If the speaker cabinet moves with vibration not a good thing.

Just my way of thinking.

I reckon different circumstances require different solutions, but to my way of thinking - and experience - coupling speakers to the floor is no good as it invites unwanted resonances, regardless of the type of flooring. There are plenty of excellent decoupling  methods that also prevent movement of the speaker cabinet.

[HAL]

After owning Von Schweikert Research VR-8 speakers for a long time, at 500lbs each, they sat on gliders on the carpet.  No movement problems as the carpet and jute pad compressed sitting on concrete.  That worked well and no spikes needed. 

[Nick B]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis.

Rich,

I like the idea of separating/isolating the power supplies. Have you ever used vibration control devices to see if you squeeze max performance out of a device? Years ago, Steve McCormack told me he was using small still points within the chassis and it improved the sound. I didn’t ask what the exact implementation was.

Nick

Nick,
I have used feet made with Navcom and Sorbothane on electronics for vibration damping.  This helps isolate any mechanical noise going either way.  I use hard points to couple speakers to the floor for stability and not moving, so the opposite of damping.  If the speaker cabinet moves with vibration not a good thing.

Just my way of thinking.

Thanks, Rich. Keep us posted with your progress. I just picked up a Holo Red streamer. A very good streamer and better than my iFi Zen. The Ultra is doing an excellent job showing the differences. Leo did a really nice job.

[Nick B]

Nick,
Not sure but the SMPS are already shielded, so might be simple with moving the amp modules away.  I really like the original Starkrimson monoblocks with the external SMPS over putting the supply in the chassis.

Rich,

I like the idea of separating/isolating the power supplies. Have you ever used vibration control devices to see if you squeeze max performance out of a device? Years ago, Steve McCormack told me he was using small still points within the chassis and it improved the sound. I didn’t ask what the exact implementation was.

Nick

Nick,
I have used feet made with Navcom and Sorbothane on electronics for vibration damping.  This helps isolate any mechanical noise going either way.  I use hard points to couple speakers to the floor for stability and not moving, so the opposite of damping.  If the speaker cabinet moves with vibration not a good thing.

Just my way of thinking.

I reckon different circumstances require different solutions, but to my way of thinking - and experience - coupling speakers to the floor is no good as it invites unwanted resonances, regardless of the type of flooring. There are plenty of excellent decoupling  methods that also prevent movement of the speaker cabinet.

My Reynaud speakers come with sliders…had no choice and they sound great. 85-90 lbs, but no problem moving on the laminate floor.

[HAL]

The prototype using two 36VDC, 600W SMPS for power. 

Wired them up and started testing them today.  They do have fans, so that will be just for prototyping.  The fanless versions are 3x the price, so want to make sure they work as I would like.

Trying larger loads tomorrow morning it that is stable, then time to try the amp modules.  Leo has already given a tip to rewire the XLR's with balanced, shielded cable for minimizing noise pickup from the SMPS.  Will shield the existing wires, as I have braid big enough to cover the wiring.

[HAL]

The two channel Pizza Box amp v2.0 has input and output wiring completed.  Just need to wire it to the SMPS.

Pizza Box Amp +/-36V@16.7A SMPS are ready for wiring to the amp modules.  Using 14awg stranded Belden 1309 cables for the DC power.

Will add a capacitor bank to the amp module pizza box to lower the impedance at the amp end and help filter any SMPS noise further.

[HAL]

Decided to go to monoblocks with external SMPS, so they are now completed.

Next is testing with an 8 Ohm dummy load to verify correct operation. 

[Nick B]

Decided to go to monoblocks with external SMPS, so they are now completed.

Next is testing with an 8 Ohm dummy load to verify correct operation.

Rich,

I think I like the look of your speakers recently a bit better 😊 But, an A+ for creativity
On Leos small monos that you own, did you try different power cords or there wouldn’t be much of a difference?

Nick

[HAL]

Nick,
Not tried the Orchard Audio Starkrimson monoblocks with new GaN power supplies with the stock power cords. 

I use them with Triode Wire Labs power cables Pete made for my setup many years ago as that is what I have in the system with the PI Audio Group BlunderBUSS and UberBUSS.  Bringing the UberBUSS and TWL power cables to LSAF.  An easy test to do at the show. 

The TWL power cables are more flexible than the stock AC power cords, so that helps with my setup.

[HAL]

Back from LSAF2023 and now for some more fun with Pizza Box Amp v2.1.

These are the fanless SMPS for +/-36V at 1kW DC output.  Should do well up to 500W without a heatsink or chassis mounting for trials.

They have adjustable output voltage, so will be making sure both sides are as equal as possible.

Next to wire them up for testing with a resistor load check.