Mod-286 build thread

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As promised and as per recent Forum member request please find attached the DXF drawing of the backplate and its cut-outs. Feel free to use it and adjust it to your particular design. I had to zip the DXF as the forum program does not allow files with DXF extensions.


FYI. For the CAD beginners among you. I used the free LibreCAD to do the drawing. Of course any other DXF capable CAD programm will suffice as well.


You can submit the DXF file to the Modushop by email, after you placed your order online. I also had initially my name and my email address written in the CAD drawings text block so Modushop has it easier to correlate the DXF to my particular order.


Have fun.

Thank you for sharing this!
 
Another build

I used a Dissipante 2U 300mm case from ModuShop for my dual mono build and sent the front and rear panels to Schaeffer for processing. Not cheap, but an excellent service and their Front Panel Designer application is easy to use.

I used Rivet Nuts on the baseplate to mount the PCBs. I also used some where the fixings for top and bottom covers go, rather than using self-tappers. I used MAX08NG clips with Keratherm 86/82 for the LM3886s and used TapTite screws rather than tapping.

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I included a Connex SMPS500R @ +/- 36V and a board from CustomWorks to accept a trigger in from the preamp.

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Here it is partnered with my Neurochrome Diff preamp. Over the moon with how it sounds fed from my media server via a RaspTouch player with an IQAudio Pi-DAC Pro. I needn't have worried about the available power, I can't comfortably have the volume past the 9 o'clock position when driving Q Acoustics 3200s.

The preamp build is here
http://www.diyaudio.com/forums/analog-line-level/290110-neurochrome-differential-preamp-build-4.html#post5446915

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Great built, I wish Tom would sell the an 286 through hole board.

The components aren't available for that. I can make a lower performance version with leaded components. It'll be on a larger board and cost more, so I've chosen not to. Pay more, get less is not how I operate. :)

I do wish that the more exciting parts were available in leaded packages. Sadly, they're not. So we have to go with SMD. Some would argue for a 'hybrid' solution. I.e. use SMD parts "when I have to" and leaded parts elsewhere. That's a pretty good idea, except for those who really can't solder SMDs (usually due to health reasons). So there'll be requests for me to solder down the ICs. That's not a big deal, but I would rather spend my time doing other things. The setup charge for automated assembly is nearly the same regardless of whether you have one component or 300 components on the board, so if I'm going to have a pre-assembled option of any kind, I might as well use as many SMDs as possible and get them all machine assembled.

Automated assembly offers many advantages, including:
  • Better circuit performance; both due to lower circuit parasitics and the ability to use better components.
  • Better and much more consistent performance due to the lower stresses on the parts (especially MLCCs) in the automated assembly process.
  • Lower build cost.
  • Much lower support cost, which means I can deliver better service to more builders and design more high-end circuits.
So basically, automated assembly allows me to deliver a higher quality product at a lower price. I think that's worth taking.

I squirm and sweat every time I drop $k on a parts order and another $k on the assembly fee, but man... it is so nice to be able to pick up a box of boards two weeks later that are ready to ship. My neck, back, and respiratory system thank me.

I think those of use who are pushing for the best performance in the DIY market will just have to get used to the idea of partially pre-assembled boards, i.e. boards with the SMDs soldered. That's the way the field is moving. We can dig our heels in and get left behind or we can choose to follow (or lead) and go to new and uncharted territory.

any plans to offer mod-286 again?

Absolutely! I'm planning to have that ready to go by the end of summer. There'll be two options:
  • Fully assembled
  • Partially assembled (all SMDs pre-populated)
I'll have a mounting bracket for it, just as I do with the '686.

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I'll announce Rev. 2.0 in the MOD286 thread in the vendor forum as well, once it becomes available.

Rev. 2.0 will be a mono-only board. So 50-60 W into 8 Ω and 100-120 W into 4 Ω on ±35-36 V supplies. The vast majority of MOD286 builders built the mono version, so I'll optimize the board for that.

Tom
 
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Duly noted. :)

The Guardian-686 and a Modulus-686 amp kit project are ahead of the MOD286.
The Guardian-686 should enter production this week and its documentation will come together pretty quickly. I'm planning to have the amp kit ready by early August as I have a buyer for the assembled amp. I'm aiming to design the chassis to be able to accommodate both the MOD686 and the MOD286 - or at least such that I can easily reuse the CAD files. I'm thinking a Modushop 3U Dissipante for the MOD686. For the '286, a 2U is enough.
In summary: The MOD286 Rev. 2.0 will likely happen in early/mid fall. October would be nice as that would allow that project to gain a little exposure before the Christmas rush.

I also need to remember to take a day off here and there to clear my head. :)

Tom
 
Hi Tom,

I am also interested in Mod-286. I plan to make my Zaph's ZDT3.5 active and need 4 Ohm capable amp. Mod-686 would be ideal but the board size is a bit too long to fit across the speaker cabinet, thus Mod-286. I would also be happy if you will offer input sensing auto on/off board at some moment. It seems practical for active speakers.

Regards,
Oleg
 
I expect the MOD286 2.0 to provide about 55 W into 8 Ω and 110 W into 4 Ω on a ±35-36 V supply. If you want more power than that, the MOD686 is where it's at.
I expect all other parameters and the sound quality of the MOD286 2.0 to be similar to those of the MOD686.

The whole point of the Modulus series is that the amplifier does not make sound. It's just there to provide power.

Tom
 
Poseidon's Voice Modulus 286^2 build

Hi again!

I'm sure a few of you are procrastinating as I had with completing a Modulus 286 build. Well, perhaps this post will serve as an impetus for you folk that need that encouraging boost ;)

Pretty self explanatory (you can click on each of the photos to enlarge them):



Over 170 SMD parts/board - loved the experience! :smash:







A lot going on here. 300VA transformer with electrostatic shielding and a steel enclosure. AMB Epsilon 24 board for momentary switches w/relay. 2 PS boards, a total of 88,000 uf of capacitance. 4 channel Modulus 286 build, hence the name Modulus 286^2.



Chassis ground - single most important part of the build; complete with a locknut for safety :sarge:



Closeup of the AMB Epsilon 24 board with relay.







When I first fired it up, DC offset on the speaker outputs initially measured about 0.13 mV for all the channels. Within about 30 seconds however, they all drifted down very close to 0mV on my Fluke 87. In late winter 2017, I built a precision 1khz oscillator (2ppm) from AKITIKA that has proven to be useful for my amp builds. It measures about 1.006 kHz and set to an output of 99 mV, I measured between 990 mV to 1010 mV on each of the Modulus 286 outputs confirming my gain setting of 10X (about 20dB to 20.17dB).

What can I say? Precision performance!

Can't wait to put it to the test in my HT setup, these will be powering my L/C/R mains with 1 channel to spare. They are 96dB efficient with an impedance minima of 4.8 ohms, so no worries there :D

If you have any questions or comments, please don't hesitate to ask. Thanks for reading!

Best,
Anand.
 
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