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Neurochrome Modulus-186: 40W (8Ω); 65W (4Ω) @ <-120dB THD Composite Amplifier Module

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Neurochrome Modulus-186: 40W (8Ω); 65W (4Ω) @ <-120dB THD Composite Amplifier Module

Update 2018/10/20: The introductory sale has started: Modulus-186: 65W composite amplifier achieving <-120dB THD
The sale will end by 23.59 Mountain Time (GMT-7) on November 30th. This will be the only sale on the Modulus-186 so get 'em while you can.

Key features (preliminary):
  • Mono construction.
  • 40/65 W into 8/4 Ω, respectively @ THD < -120 dBc.
  • Tested for stability with reactive loads up to 1.0 µF || 8 Ω.
  • Multi-tone IMD residual: < -105 dBV.
  • Damping factor: >500 @ 1 kHz; >225 @ 20 kHz (8 Ω).
  • Integrated noise (20 Hz - 20 kHz): 17 µV (A-weighted); 22 µV (unweighted) @ 20 dB gain.
  • Integrated noise (20 Hz - 20 kHz): 23 µV (A-weighted); 28 µV (unweighted) @ 26 dB gain.
  • Balanced input (can be connected to unbalanced sources as well).
  • Default gain: 26 dB for ease of use with other HiFi components. 20 dB available upon request. Higher gain possible by a simple resistor swap.
  • Four-layer PCB, fully optimized for the highest performance.
  • Designed, manufactured, and assembled in Canada. All components sourced from reputable distributors (Mouser, Digikey, et al.)
  • Available for pre-order within the next few days with a significant early adopter discount. Expected in stock by the end of November, 2018, at which point the into sale will end.
The Modulus-186 is a composite amplifier, which uses an LME49720 to perform error correction on an LM3886 power amplifier. This results in an amplifier which has the precision of the LME49720 and the power of the LM3886. This error correction is the central point of the Neurochrome Modulus composite architecture. The composite design will correct for many types of error, including distortion and power supply induced errors. It is due to this architecture that the Modulus amplifiers achieve their high performance levels as evidenced by their ultra-low THD, IMD, multi-tone IMD, etc.

Note that attached picture and measurements are of the prototype. I will follow up with a more comprehensive set of measurements once the production version is in.
The production version will be Neurochrome Blue and professionally assembled in Calgary on a gold-plated PCB made in Ontario, Canada. The finished module will include aluminum mounting hardware (also made in Canada), which allows the module to be bolted directly onto a heat sink. This mounting method greatly simplifies the mechanical work for the the DIYer (only two holes needed with ±0.5 mm precision in their location).

Enjoy.

Tom
 

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  • Modulus-186 PROTO_ THD+N vs Frequency (20 dB, 40 W, 8 ohm, 60 kHz BW).PNG
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  • Modulus-186 PROTO_ THD+N vs Output Power (26 dB, 1 kHz, 8 ohm, 20 kHz BW).PNG
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  • Modulus-186 PROTO_ Multi-Tone IMD (AP 32-tone, 40 W, 1M FFT, 8 averages).PNG
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So Tom, would you expect better performance for the Mod186 vs. the Mod86?

The answer lies in the custom SMD based input stage of the 186 (no more THAT 120X series) and lowered noise floor amongst other things along with the precision pretested modules.

Easy decision if you ask me and if the power is right for your application.

Best,
Anand.
 
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So Tom, would you expect better performance for the Mod186 vs. the Mod86?

Absolutely! As Anand pointed out, one of the main differences is the reduction in noise floor, thus the THD+N at 1 W, for example, is cut in half. The residual mains hum, which in the MOD86 is low already, has been reduced by at least 15 dB and is now firmly below the noise floor.

Another big change is that I get to serve the OEMs, makers, and less experienced DIYers much better. In the past, I built the Modulus modules by hand. That severely limits my ability to sell the finished modules in high volume. It simply takes me way too long to build them. Thus, by relying on automated assembly for the majority of the parts and hand-assembly (by my assembly house) I get to focus on growing my business - both to my benefit and to the benefit of everybody else.

Tom
 
Anand,

Well I am in the middle of building 4xMod86’s to use on a LXmini, which I will use for a while. Longer term I was looking at building a pair of Mod686/Mod286 or Mod186 amps to use with the LXmini’s. I would repurpose the 4xMod86 to my surround system powering some full range drivers. Well I populated the resistors on all the Mod86 boards, now on to the diodes.
 
Absolutely! As Anand pointed out, one of the main differences is the reduction in noise floor, thus the THD+N at 1 W, for example, is cut in half. The residual mains hum, which in the MOD86 is low already, has been reduced by at least 15 dB and is now firmly below the noise floor.

Another big change is that I get to serve the OEMs, makers, and less experienced DIYers much better. In the past, I built the Modulus modules by hand. That severely limits my ability to sell the finished modules in high volume. It simply takes me way too long to build them. Thus, by relying on automated assembly for the majority of the parts and hand-assembly (by my assembly house) I get to focus on growing my business - both to my benefit and to the benefit of everybody else.

Tom

Is the LME49720 used to avoid the pole-zero compensation of the OPA1611 I think you used on the Mod 86? Looks excellent as usual :).
 
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I would repurpose the 4xMod86 to my surround system powering some full range drivers.

That'd be a nice amp for the surround channels.

Is the LME49720 used to avoid the pole-zero compensation of the OPA1611 I think you used on the Mod 86? Looks excellent as usual :).

Yep. The LME49720 offers quite a few nice features. Among them:
  • Very low distortion.
  • Single-pole response to UGBW.
  • Reasonably low noise.
  • Decent offset specs.
  • Lowish cost.
I like it. :)

Tom
 
Will you be offering bare PCBs to those of us who are comfortable with SMD soldering?

I will not. Sorry.

Focusing on the fully assembled modules, rather than spreading myself out over 2-3 product options per product, allows me to get better bulk discounts on the components and on the assembly. This benefits you in terms of lower prices.

Automating the assembly also means that you get better and more reliable and more repeatable performance. I consider myself to be quite handy with a soldering iron. I've been soldering since I was five years old - so nearly 40 years. I've received formal training in it twice. Yet, my hand-soldered boards do show some board-to-board variability. It's not earth shaking, but if you measure ten boards, they do show up as a somewhat broad band on the distortion analyzer. If you measure ten of the professionally assembled boards, they show practically as line-on-line.

Better performance. Lower price. What's not to like? :)

Tom
 
On the price thing, I suppose the costings of the modules if the stated amounts are per channel appear to put it at a different point to the self assembled Mod86 ($69 board and design + $58 BOM inc inductor).

I still see that the new boards are very good value, but they are a bit out of range for a "just because" project.
 
The just because project becomes an obvious bargain ;) when you listen to one fully built or understand that the performance here is at least at the level of Benchmark AHB2, the finest NCore modules, etc...

A colleague of mine has listened to the Modulus 86 (thru hole), the SMD Modulus 686 and ICEedge 1200AS on a high sensitivity system. The choice for him thus far is the 686, no question.

Hope that helps.

Best,
Anand.
 
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Mr Kettle, I’ve owned a fair number of makes, models and power levels of Connery amps, as well as having assembled lots of kits and scratch-builds during the last 50 yrs - the latter including both generations of the ACA, as well as Hypex, Sure and YJ ClassD .

I’m not exactly sure what you mean by “just because”, but after a couple of too short experiences with a total of three different pieces of Tom’s in several systems with which I’m quite familiar, I’d describe them as more than just a novelty for a collector / dilettante.
I now find myself in the same position as wcwc in another current thread - how to choose between the 186 or 286, particularly after hearing the 686 annihilate the onboard power amp stage of my Onkyo HT receiver, and the Hypex UCD 180 driving the subs in that same system.

Now, when my Powerball lottery comes in, such plebeian concerns will evaporate - but until then, I gotta start collecting empties from the family BBQs.
 
A "just because" project is one where the resulting item isn't something you need (I don't need another amp) but the process would be interesting. My personal preference has so far been for valve amps, especially with my ESL63s, so there is a possibility that, as good as a set of Moduli is, that would still be the case.

Being over in the UK, while there are some people who have built the existing through hole versions they are a bit few and far between at the moment so there isn't really as much opportunity to try out the idea first.
 
I'm pretty sure Abraham Maslow would agree that hifi equipment is not a survival need, though he might argue that DIY audio would fit within the self-actualization need. Then again, Maslow is a hack... :)

If you like low-distortion amps, you'll love the Modulus-series. If you're expecting to have the amp add a little "something-something" to the sound, you'll probably either be disappointed or grow to like the clean sound.

There are many aspects to pricing. One such aspect is OEM pricing. The first thing OEMs ask for is a discount, so pricing your products at cost is a non-starter if you want to break into the market of OEM modules. It also turns out that if you only charge at cost, you don't make any money. In that case, you have a hobby rather than a business. I run a business and depend on it as my only source of income (by choice). I can't afford to sell stuff at cost.

I'm looking at investing about $10k getting the first batch of MOD186 and MOD286 fabricated. There's no way I'd make such an investment and take on all the risk in exchange for nothing.

Sorry, but that's reality from where I'm sitting. :)

Tom
 
MrKettle - just how many luscious tube(ish) watts are you looking for? Another recent quite easy and affordable build that has much of that signature is the DIY Audio ACA kit. Up to 15W@8 ohms of SET class A in bridged monoblock on balanced input. A very pleasant sounding piece, easy peasy build, and in both full kit or PCB & parts versions, still quite a bargain in my books.
However, notwithstanding the difference in output power, to my ears there are as transparent, nor had quite the taut grip in the bottom octaves as the Modulus. Of course all my comparisons were quite lopsided in terms of power :
- an early ACA stereo build with the 19V supply (5W), to the LM3886DR and Modulus86;
- mono block pair of ACAV1.5(6?) 24V supply (15W), to Modulus 686;
and all all were on boxed moving coil drivers- either single driver “full range”, or 2way MTM, so definitely not apples to apples, and not easily extrapolated / translated to what you might want/need.
 
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Apologies, this isn't meant to be a massive thread divertion.

Lush valve SET 2% sdcond harmonic colouration isn't what I am after or what I have got at the moment to my ears. The main amp currently is a World Designs WD88VA, supposedly rated at 36W class A (not sure at what THD off my head) from a pair of KT88/6550s PP with some feedback applied. It seems to be able to portray a variety of tonal colour such that there is a clear difference between violins and violas when on the recording but without there obviously being an overall colour shift.

To put it another way, the Bliss Colour Symphony isn't all Three Colours Red or Kind of Blue...

I'm not a volume fiend, but from other people's experience an ACA probably wouldn't be suitable. What sparked the possible interest was the subjective reviews from people who talked about tonal colour, as quite often what people don't talk about can be a good indicator of what a component o nsystem doesn't do.
 
No worries, I should probably share culpability for any diversion.

If the 186 is discernibly an audible improvement over the Mod86 I heard a couple of years ago, that’s more than good enough for me. Having owned more than a few tube and SS amps with signatures, with the particular systems I’m currently running, I’d prefer to have as little of that as possible, and the Moduli familty certainly seem to fit that bill.
 
I expect the Modulus-186 to be similar in "sonic character" to the Modulus-686 when used within its power envelope. Those who use efficient speakers or more reasonable SPLs (say 80-85 dB average SPL 2-3 m from the speakers) will likely enjoy it.

Those who like to crank it louder or who use bass EQ will likely enjoy the Modulus-286 and -686 more.

I know the terms "straight wire with gain" and "transparent" are overused, but that's what I'm aiming for. Or "Blameless", perhaps. I want the amp to just be along for the ride and not provide any character, colour, or tone not present in the incoming signal. What the rest of the signal chain does with it is beyond my control.

Tom