AudioCircle
Industry Circles => Hollis Audio Labs => Topic started by: HAL on 23 May 2023, 11:27 am
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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.
(https://www.audiocircle.com/image.php?id=253105)
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Hal: You are bad as I was in the 90s. For a while, I ran a car sub in a cardboard box.
PS: I hate when things get throw away when they could be recycled. I could have given you an authentix Tony's box.
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mixrfix,
Thanks for the thought.
Was using school pencil boxes when I was a kid for projects. Even one for a Science Fair project and won a prize! :)
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Participation trophy!
But, wouldn't it get hot with the box closed?
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Only if I do not put holes in the top. I just leave it open when running. :thumb:
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What are your thoughts on these vs the non-ultra ones?
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P.S.
Use twisted shielded pair wire between the XLR connector and module input. Like this one...
https://www.digikey.com/en/products/detail/belden-inc/9451-008500/7042018
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Leo,
Once they are up and running will let you know.
These are still in build as I need a few more parts for testing.
One person I know called my Chip Amp project in a box lid the Pizza Box amp, so the name stuck for this type of project. :thumb:
I have some Mogami Star Quad shielded cable to use when I get new XLR Female chassis connectors.
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The two SMPS for +/-36VDC at 16.7A is up and running. These have fans so they can run both 250W amp modules simultaneously.
The wiring is 14awg for DC power, so might try remoting the two SMPS in another pizza box for EMI/RFI reduction to the amp wiring.
(https://www.audiocircle.com/image.php?id=253141)
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The two SMPS for +/-36VDC at 16.7A is up and running. These have fans so they can run both 250W amp modules simultaneously.
The wiring is 14awg for DC power, so might try remoting the two SMPS in another pizza box for EMI/RFI reduction to the amp wiring.
(https://www.audiocircle.com/image.php?id=253141)
If those SMSPS have adjust pot see if you can get +/-40 out of them to get a bit more headroom.
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Yes, they have an adjustment pot. Will see what the range is with changes.
About ready to try it with higher current loads, so will see what adjustment range I can get.
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I look forward to hearing which brand pizza box sounds the best. :icon_lol:
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"might try remoting the two SMPS in another pizza box for EMI/RFI reduction to the amp wiring."
dual chassis amp? now you've really entered the high end :lol:
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The input and output wiring is done in the two channel pizza box. Easy enough to go dual mono, just add one more pizza box.
Will put a seperator between the channels.
Now for connection to the SMPS to try them out. Yes they are going in another pizza box. :thumb:
(https://www.audiocircle.com/image.php?id=253150)
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Pizza Box Amp +/-36V@16.7A SMPS 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.
(https://www.audiocircle.com/image.php?id=253151)
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This is like the 21st century version of SET.
Will the amps overheat if you close the lid?
BTW, headroom is strictly class ab where triple the rated power is on tap. From a regulated PS, I don't think so, that's why 250W minimum is the cutoff point for class D.
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The GaN devices are fine up to 200C, so I doubt that the lid closed will be a big deal. If so, then put a screen mesh on the top for heat escape. An IR thermometer will tell.
Only if the load is 8 ohms would it be 250W. It will double to 500W into 4 Ohms and 2 Ohm stable, so yes, the headroom is needed for two amps running 4 Ohm or lower loads.
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The GaN devices are fine up to 200C, so I doubt that the lid closed will be a big deal. If so, then put a screen mesh on the top for heat escape. An IR thermometer will tell.
Only if the load is 8 ohms would it be 250W. It will double to 500W into 4 Ohms and 2 Ohm stable, so yes, the headroom is needed for two amps running 4 Ohm or lower loads.
The overtemperature protection kicks in at ~80C. Even though the GaN devices can handle higher temperatures there are many parts close to them that cannot.
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The overtemperature protection kicks in at ~80C. Even though the GaN devices can handle higher temperatures there are many parts close to them that cannot.
80c sounds okay before thermal protection kicks in. 200c for even a moment being something that sounds reasonable is why this attraction to the business of hi-end (expert) audio escapes me.
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The overtemperature protection kicks in at ~80C. Even though the GaN devices can handle higher temperatures there are many parts close to them that cannot.
So 80C is 176F for the other parts and I understand as even good electrolytics are 105C rated for some number of hours. The heatsink is on the bottom of the pc board, so will vent the top and bottom for air flow.
Would rather deal with that then having to deal with SET heat output to other posted mentions. No need for extra air conditioning to deal with the heat loads.
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The dual mono Pizza Box Amps v2.0 are completed and connected to the individual SMPS. Will vent the boxes for air movement top and bottom.
Will be time to give them a try with the speakers once I do some audio testing with my 8 Ohm dummy load.
(https://www.audiocircle.com/image.php?id=253189)
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Do not burn down your house.
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mix4fix,
Will be very careful with testing. The 8 Ohm loads will get hot, so I put them on heatsinks for extra heat dissipation and non-flammable material.
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I am talking about the amplifiers.
Putting a entry-level subwoofer in a cardboard box when your broke and bored in the 90s is one thing. But, it's not a good idea to have heat producing electronics in an enclosed container that can catch fire is another.
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mix4fix,
Will be very careful with testing. The 8 Ohm loads will get hot, so I put them on heatsinks for extra heat dissipation and non-flammable material.
You're sticking to this?
This guy is playing you. Doesn't anyone realize it?
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The pizza box Amp would be even more epic if you added rack ears :icon_twisted:
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I am talking about the amplifiers.
Putting a entry-level subwoofer in a cardboard box when your broke and bored in the 90s is one thing. But, it's not a good idea to have heat producing electronics in an enclosed container that can catch fire is another.
Only the amps and SMPS are in the Pizza Boxes, the subwoofers are in wooden cabinets made for them.
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You're sticking to this?
This guy is playing you. Doesn't anyone realize it?
I know mix4fix, he is a local member of the DCAudioDIY group.
I have seen 12in sub speakers go up in smoke with high power input. He is not wrong when using this amount of input power for safety in the cabinet material.
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The pizza box Amp would be even more epic if you added rack ears :icon_twisted:
LOL!
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From this, you can gauge how much power the modules will be dissipating...
Orange and Blue are efficiency for 8 and 4 ohms
Grey and yellow are dissipation for 8 or 4 ohms
(https://orchardaudio.com/wp-content/uploads/2022/09/Rev_3.0_Efficiency.jpg)
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Leo,
Excellent!
Looks like if I run the 4 ohm sub setup the max dissipation at ~500Wrms is about 23 watts. That would be 4 woofers in parallel wiring load.
Should do very nicely! :thumb:
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Leo,
Excellent!
Looks like if I run the 4 ohm sub setup the max dissipation at ~500Wrms is about 23 watts. That would be 4 woofers in parallel wiring load.
Should do very nicely! :thumb:
Yea, but in reality it will be much less because typically audio average power is about 1/8 to 10th of the peak. So if you are peaking at 500W your average power will be somewhere around 50 to 75W.
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The pizza box Amp would be even more epic if you added rack ears :icon_twisted:
Don't need that. They make those pizza racks like
https://www.katom.com/cat/pizza-holding-cabinet.html
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Don't need that. They make those pizza racks like
https://www.katom.com/cat/pizza-holding-cabinet.html
:o LOL!
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I want to know if you could cook a pizza in the middle if you put one amp on top and another on the bottom?
:scratch: :popcorn:
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Amp looks a little cheesy :roll:
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I want to know if you could cook a pizza in the middle if you put one amp on top and another on the bottom?
:scratch: :popcorn:
Methinks getting one of those pizza racks with 3 shelves, one amp on top shelf, one on bottom, actual pizza in the middle could keep the 'za warm while listening to some raucous tunes.
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Well since the amp only dissipates 23.5W for 500Wrms into a 4 Ohm load, so not going to do much to keep the pizza warm. :lol:
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Well since the amp only dissipates 23.5W for 500Wrms into a 4 Ohm load, so not going to do much to keep the pizza warm. :lol:
Means that Class A is better for this use :-)
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Not in summer time! :o
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Any more progress on this Rich? How is it working out for you?
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Leo,
Ran out of time to finish and test them before the 4 day drive to Dallas for LSAF2023.
Room is setup for Day 1 of the show. It sounds really good with the Starkrimson monoblocks driving the planars! :)
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Leo,
Ran out of time to finish and test them before the 4 day drive to Dallas for LSAF2023.
Room is setup for Day 1 of the show. It sounds really good with the Starkrimson monoblocks driving the planars! :)
Have fun and good luck.
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Leo,
Thanks!
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I am about to be as bad as HAL.
I am thinking of using my "plastic" cardboard speaker box project, and I will probably use the guts from a computer sub-woofer as a full range mono amplifier.
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I used school pencil boxes as project boxes when I was young. Hard to beat at around $0.50 each.
Working on the new fanless SMPS for PBA v2.1 to try. The fans in the 600W units are very loud, so have 500W fanless supplies to try. Not using that much power, so should be fine. Will be testing those soon.
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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.
(https://www.audiocircle.com/image.php?id=253814)
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Time to get back to the amp project.
Will be wiring up the new Mean Well fanless SMPS this weekend and give them a try. Just reusing the wire harnesses from the original SMPS for testing then some listening.
The MG10QR's should be a great test using these on the bass panels and the original Starkrimson monoblocks on the quasi-ribbons. The dspNexus 2x8 DSP crossover is ready to try driving the amps in a biamp then triamp system.