I got this one:
2PCS MC2620 Mono Aluminium Chassis Split Amplifier Class A Amplifier Chassis|Amplifier| - AliExpress
Btw, I will only use one half of the heatsinks. Reserve the other side for future upgrade to SuSyLu 100w Class A amp. 🙂
2PCS MC2620 Mono Aluminium Chassis Split Amplifier Class A Amplifier Chassis|Amplifier| - AliExpress
Btw, I will only use one half of the heatsinks. Reserve the other side for future upgrade to SuSyLu 100w Class A amp. 🙂
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Each heatsink can handle the 75w from 3x MOSFETs plus 12w from LU114D easily. Circa 90w max - similar to what a 4Ux300mm can do. This is 345mm deep by 200mm or 4.5U so plenty of capacity.
The SuSyLu is bridge tied load (balanced) amp with choke load so is actually quite thermally efficient.
Up to 100w/(87w x 2) = 57% thermally efficient at full power (or better as the dissipation. Actually decreases when the power goes to the output at higher power. I have measured that a SE Class A amp runs cooler when playing at high power. Almost approaching Class AB 67%.
But terribly inefficient at low power - same 87w x 2 dissipation.
The SuSyLu is bridge tied load (balanced) amp with choke load so is actually quite thermally efficient.
Up to 100w/(87w x 2) = 57% thermally efficient at full power (or better as the dissipation. Actually decreases when the power goes to the output at higher power. I have measured that a SE Class A amp runs cooler when playing at high power. Almost approaching Class AB 67%.
But terribly inefficient at low power - same 87w x 2 dissipation.
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Some progress on making the +/-35v DC/DC converter for the LuFo OPA454 front end board. The LT8364 takes the +28v input and converts it to a dual rail isolated supply via a coupled inductor in a single ended primary inductor converter (SEPIC) topology.
Yes, the Yarra with Melbourne if you have the proper PSU trafo to generate 50vpp. I think the 22v secondaries make about +/29.5v. It is barely enough as I recall.
Or use the new OPA454 boards described above, or the soon-to-be-made Aksa Lender board and DCDC PSU board.
Or use the new OPA454 boards described above, or the soon-to-be-made Aksa Lender board and DCDC PSU board.
That’s a nice chassis too. Only one heatsink but that’s all that is needed for a LuFo. The dual heatsinks are useful for the SuSyLu.
Btw, I have to say that I am extremely happy with the quality of the CNC work and fit and finish of the aluminum chassis from my vendor on AliExpress. Everything is machined out of aluminum. There are no sloppy stamped steel frames with misaligned sheet metal screw holes to deal with. The panels are solid and don’t flex. All panel cutouts are premade. The shipping is a killer but price and quality is still better than anything you can get elsewhere in the US or EU for similar price.
And a 'Summer Sale' on some items, which ends tomorrow.
E.g.: DIY A amplifier case 245*180*257mm 180A Full aluminum amplifier chassis / Desktop Class A amplifier/AMP Enclosure/case/ DIY box|Amplifier| - AliExpress
E.g.: DIY A amplifier case 245*180*257mm 180A Full aluminum amplifier chassis / Desktop Class A amplifier/AMP Enclosure/case/ DIY box|Amplifier| - AliExpress
That’s a nice basic case too. You will need to spread the heat output to both sides though. One side is good for maybe 45w. I have used a similar size for a Class A headphone amp and it was able to handle 75w total both sides. No pre-drilled holes cutouts though.
The OPA454 front end board for the LuFo is now assembled. I have to say that it looks really cool in a double stack. The PSU board has been tested and verified to make +/-35v from a single 28v supply.
A bit more progress tonight. Second channel powered up smoothly. I was able to match the MOSFETs Vgs a little closer on this channel because I found 6 more of the same FQA’s in my parts stash. That did make a measured improvement with the current sharing between the three Mosfets.
Soooo close to hearing the LuFo in stereo, one more night!
Btw, this amp is getting heavy!! 😱
Soooo close to hearing the LuFo in stereo, one more night!
Btw, this amp is getting heavy!! 😱
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Nice work, Vunce! That LuFo chassis has got to be a fatty! 🙂
I made more progress as well. The OPA454 is singing away with the P2P LuFo amp! Sounds great! 22.4dB plus 6dB from my usual BTSB preamp is about perfect amount of gain at 28.4dB overall. With music off the amp is still silent. Can’t tell it is turned on. No hiss, no noise, no hum.
The +/-35v DC/DC converter is running off a 12v Class 2 linear wall wart and seems to work just fine. It accepts a wide range of input voltages. I have also tested with 28v input of course.
JPS64 did another superb layout on the OPA454 front end. Thanks, JPS64!
I made more progress as well. The OPA454 is singing away with the P2P LuFo amp! Sounds great! 22.4dB plus 6dB from my usual BTSB preamp is about perfect amount of gain at 28.4dB overall. With music off the amp is still silent. Can’t tell it is turned on. No hiss, no noise, no hum.
The +/-35v DC/DC converter is running off a 12v Class 2 linear wall wart and seems to work just fine. It accepts a wide range of input voltages. I have also tested with 28v input of course.
JPS64 did another superb layout on the OPA454 front end. Thanks, JPS64!
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Great work and progress all round. There is no stopping this dynamic duo (trio if we throw JPS into the mix)
Congrats
.. dB
Congrats
.. dB
Thanks, guys. I think we may have stumbled upon a universal high swinging output stage for all of the 0dB gain amps: F4, MoFo, LuFo, SuSyLu, etc.
Once I add second channel all it needs is 12v from a wall wart and you are set. 0.0008% THD with 125mA drive capability. +/-35v (can be adjusted to be as high as +/-49v).
Once I add second channel all it needs is 12v from a wall wart and you are set. 0.0008% THD with 125mA drive capability. +/-35v (can be adjusted to be as high as +/-49v).
Can you run it off the positive amp rails instead? Prefer not having to deal with another power input to the amp.
Yes, it was actually designed for that. I have tested it with the 28v from the amp. It was just more convenient for testing as I did not have a wire from my main 28v rail handy.
When you bolt this front end to the LuFo main board, you will automatically make the connection to the +ve rail and the signal input and output via the standoffs which also provide electrical contact.
Notice the five brass standoffs on the LuFo verification build that Vunce is doing. That’s where this goes and all electrical connections will be handled automatically.
When you bolt this front end to the LuFo main board, you will automatically make the connection to the +ve rail and the signal input and output via the standoffs which also provide electrical contact.
Notice the five brass standoffs on the LuFo verification build that Vunce is doing. That’s where this goes and all electrical connections will be handled automatically.
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Great project.
I was playing with LTSpice and I simulated LuFo with Jfet/tube front end. Here is the result.
I was playing with LTSpice and I simulated LuFo with Jfet/tube front end. Here is the result.