How to Build a Neurochrome Modulus-86 High-End DIY Audio Amplifier

[@tondekleer5988]

Great video! I am currently building a second amplifier based on modulus-86 3.0. I build it for a friend who listened to my modulus-86 2.4 amplifier for a while.

[@cobar5342]

I made one of these some years ago and it is great. From Australia

[@jasonw6993]

Great stuff! Can't wait to see a tour of the Neurochrome lab. :)

[@josefk5659]

I was really hoping the final test includes you cracking open a Labatt Blue and blasting some BTO.

[@matthewspencer2094]

Thanks, part way through a similar project; it's great to watch & learn from someone who knows what their doing.

[@46Bobbie]

You mentioned a bill of materials. Am i just missing it? Could you tell me where to find it? thanks

[@ronaldmcdonald2456]

Great video! Always nice to see how an expert does it because it let's you see firsthand what you need to do to up your game. Now...let's have a discussion about Maples Leaving.😄

[@malatestasdream6764]

Great video, Tom. Building one of these kept me busy during the first UK lockdown. Got a great sounding amp first time, use it daily. Thank you!

[@janinapalmer8368]

I can't wait to see what's in this amplifier and see the schematic diagram ... that would be far more interesting than seeing the order in which it's put together ...

[@thomascorcoran5641]

Hi Tom - thanks for the interesting videos and info on your website. For projects like this, how important is underlying component selection? Is it a case of if a 20k 5% resistor is called for then any old 20k 5% resistor from the spare parts drawer is fine? Or I see "audio grade resistors" for £10 a piece (and everything in between). Or certain components or parts of the circuit are more important than others? Appreciate your boards come with BOM etc where you've done this work already, but for my broader knowledge!

[@Neurochrome2010]

I specify ±1% tolerance metal film resistors on the BOM. There's no need for fancy "audiophile" resistors,. If you have a resistor kit already, I'd just use what you have. Just stay away from carbon composite resistors as they have very high excess noise. Carbon film is OK but metal film is preferred. Also note that I have a Modulus-86 Stereo Kit available. It comes with all the necessary parts so you don't have to hunt for them: neurochrome.com/products/modulus-86-stereo-kit

[@thomascorcoran5641]

@@Neurochrome2010 thanks Tom. And for other components is it a similar story? As long as the components meet specification it should be ok? Just sometimes hear about people upgrading components of existing equipment and wondering if there's anywhere that's worth spending a bit more for higher quality, or standard stock stuff is fine in general for this type of design? Your kit is in my potentials list (though import duties to UK add some unexpected extra pain, and 2 unpopulated boards keeps it under the £135 duty threshold), may just need some practice first before jumping!

[@Neurochrome2010]

Honestly, in my not-so-humble opinion, the main feature of audiophile components is that they drain your wallet much, much faster than regular components. Audiophile components typically have worse specs on parameters that can be measured objectively. For example, I measured some audiophile capacitors a while back while I had access to an HP 4194A impedance analyzer. The audiophile capacitors had higher ESR and ESL than the plain vanilla Panasonic part from Digikey, i.e., the audiophile capacitors were further from the ideal capacitor than the off-the-shelf parts even though they were 40x the cost. There is no need - I repeat: no need; none; at all - for audiophile components in the Modulus-86 or any other circuit that I design. If you want to geek out with audiophile components you're free to do so. Just keep in mind that you will most likely get worse performance and you will pay much more. In the best case scenario there will be no difference between the performance with the audiophile parts and those I specify on the BOM, but there will be a significant cost added with the audiophile components.

[@zoenagy9458]

Please make a kit for LM1875 15-20W too, not everyone need the power of LM3886.

[@GavinHodgson]

Great work

[@paulwomack5866]

Given the high PSRR, is there any (great) benefit in having dual power supplies, or would a shared one serve?

[@Neurochrome2010]

I see no benefit of dual mono if that's what you mean.

[@anandshah71]

Is it possible for you to make a dsp use case is I have a few subs need to play around with different subs and I don’t want to buy a Dayton plate amp

[@Neurochrome2010]

You could use something like the MiniDSP SHD or similar.

[@JamesBrown-jy5sy]

Hi Tom, Very informative video! Just curious what brand/type of solder you use? Thanks!

[@Neurochrome2010]

63/37 Sn/Pb solder, 0.5 mm diameter, with water soluble flux. I forget the brand. Probably Kester. Could be AIM.

[@MicrosiMe]

Tom, Very good

[@djhatton]

nice work. are you gonna do a smd rev?

[@Neurochrome2010]

I already have the Modulus-186 and Modulus-286 for that.

[@matthewgeorge8273]

A couple of questions about the case. (1) Will it also accomodate the guardian modules? (2) Is this a case that you are planning to offer on your site?

[@Neurochrome2010]

Yep.

[@paulwomack5866]

When you get to the actual part insertion and soldering, the camera angle is far too wide - needs to be a close up. If you don't want to reshoot (and I wouldn't blame you) it might be worth zooming in on a re-edit. It will degrade quality, but it will at least show what needs to be shown. On the clip lead before/clip lead after debate, I watched some fabulous 1970's instructional videos on soldering, from the avionics trade. They bent the leads, cut the leads (so they're before-ists), then soldered. They emphasised the importance of having the cut end become embedded (and wetted) in the final solder mass. This probably doesn't matter for domestic audio! There's a bit of a lurch in the video at the end - the assembly is done with minimal tools (no "helping-hands", no lead bender, no pcb holder). This is fine, it's a fairly introductory level video. Then at the end you suddenly go all "current limited PSU, signal generator, but I guess most of you don't have THD analysers" That's quite the gear change!

[@Neurochrome2010]

I agree. This is only my third video ever, so I'm learning. I tried zooming in on the "camera" (iPhone) but that made the image quality pretty grainy. I'll figure something out.

[@tubeofmystery]

@@Neurochrome2010 let me know if you ever need any motion graphics! I'd be more than willing to do a trade-out with you!

[@gamiwv]

$150 JUST for 2 pcbs with LM3886 ? Is it gold plated (the pcb) or something ? Is it a community project or not ?

[@frosty129]

I'm curious why don't you find a cheap assembly service and outsource this tedious soldering task so that your customers don't have to sit and solder hundreds of components one by one? I think that will sell better in an audience that's not experienced in assembling electronics and want something to just work out of the box.

[@Neurochrome2010]

This amp is intended for DIYers. The whole point is that they get to build it themselves. For fully assembled modules, I offer the Modulus-186, -286, and -686.

[@fibranijevidra]

$75 just for a bare PCBs?! Makes no sense.

[@Neurochrome2010]

No? You don't think you should pay for the engineering that went into that PCB or the circuit it contains?

[@fibranijevidra]

@@Neurochrome2010 Offcourse I do. I have purchssed other peoples designs, and I have sold my designs too. I just think 75$ is too expensive. Good luck with your work.

[@sc0or]

I apologize, but low distortions do not mean hi-end. 1F of capacitors, 500% in a reserve for a power supply, golden coated relays and plugs, true glass windows, a specific sound, wattage amount - all of these and many things more, are signs of a hi-end device. When you loop a negative feedback over two OP amps, this is good, but is not enough. A sound can be dry and flat even with 0.0001% of THD. But, good luck anyway.

[@EK-em2zv]

He forgot the magic fairy dust as well in his soldering tin, what an amateur!

[@fonkenful]

sc0or - I’ve been in this hobby for over 50yrs, and have built a few kits during that time - starting with several models of Hafler pre and power amps from early ‘80s through various early Bottlehead offerings (Foreplay/ Paramour 2A3) to most recently a design that I think most would agree is at the opposite end of the spectrum of design topologies from Tom’s - Nelson Pass’ delightful ACA. Compared to classD amps in my collection - Hypex UCD180 and ICEPower A200, and even an old Topping TP30 in a desktop system, I find my current Modulus286 (one of the prefabbed SMD series) to be both utterly transparent and far more emotionally involving than any classD I’ve yet played with, and less of a euphonic tone control* component than any of my numerous previous tube amps, or single ended classA SS designs I’ve heard. * Not that there’s anything wrong with such system - I’ve owned several - but it’s just not for me these days;of course that could change - there are no permanent absolutes. As best as I can discern, there is no magic unicorn horn fairy dust involved in any of Tom’s designs. Yes, ultra low distortion in the electronic signal train or flat within +- 1db frequency response in a loudspeaker look good on paper/ computer screen but can often rob a system of some of the emotional impact, as a short listening session Tom and I recently attended this past weekend readily demonstrated. Between the three of us attending, there must have been well over 100yrs of accumulated listening and decades of amp and speaker building, yet there wasn’t complete consensus on what we “heard”. In addition to variations in measurable hearing acuity (two of us older gents were equipped with digital hearing aids), and while many will acknowledge the role which subjectivity plays, the combination of builder’s pride and anticipation/ confirmation bias are far more powerful than most of us are willing to accept as explanation for the notes we might make on a score card. This is one of the reasons why I generally eschew such listening test sessions. Anyway, just some thoughts, y’all have a good day.