Review and Measurements of Neurochrome Modulus-286 Amp

[Ground Noise Industries]

Does the Rane MA3 have error correction? That's the central point of the Modulus amps. The error correction drives the distortion into the abyss. That's why the Modulus-86, -286, and -686 sound much better than other LM3886-based amps.

Tom

I’m pretty sure it doesn’t. Transformer and unregulated linear PS. Regulated for opamps. I think there is a VCA between the input/HP Filter and the LM3886 for the compressor. You can jump over to the rane site and see the schematic in the pdf tab. I’m sure that is one reason the Modulus-86 costs more. Engineered circuit to get the most out of the chip. Rane’s amp was for background amplification like a restaurant. But certianly could be used as a home amp to drive easy load speakers.

Not sure if it okay to post urls. This is important to the differentiation between the Modulus-86 and the Rane MA3 that both use the LM3886 monolithic chip.

MA3 Multichannel Amplifier

The MA3 is a 3-channel amplifier designed to operate reliably in commercial environments, for use in paging, foreground and background music distribution.

www.ranecommercial.com

 

[tomchr]

It's a bit complicated with the compressor section in the schematic, but the LM3886 is used without error correction in the MA3. Comparing it to the Modulus-86 is like comparing a Yugo to a Ferrari. They both have a wheel in each corner, but the comparison kinda stops there.

Tom

 

[Gremlins]

I confirm that mod86 sounds great, has a spécial clarity character

 

[LionIT]

Modulus-86 R2.4 owner here.
This revision is the one with single-ended output stage, which I honestly prefer.
Despite this, the noise from the tweeters is literally zero, even 1cm from the cone.
Superb realization by Tom.
Another thing I find fantastic (and rare) is the DC servo circuit. Zero worries about any offsets.
In my opinion, the Modulus family should deserve the same attention as the renowned high-performance D-Class.

 

[pma]

Regarding output signal purity, well designed class AB will always be better than any and best class D as known by now. This means, better than both Hypex and Purifi. I am not saying it would be or would not be audible. Just technically, well designed class AB is free of any kind of ultrasonic noise content. We can still debate if the ultrasonic content from class D may have some effect in speakers/drivers, but best way is just not to send it there. The only advantage of well designed class D is better power efficiency, thus less requirements on heatsinks and weight. This is the one and only class D advantage. Nothing else.

 

[Ground Noise Industries]

It's a bit complicated with the compressor section in the schematic, but the LM3886 is used without error correction in the MA3. Comparing it to the Modulus-86 is like comparing a Yugo to a Ferrari. They both have a wheel in each corner, but the comparison kinda stops there.

Tom

The Rane MA3 hits the scales at 26lbs (11.79kg). It is really for permanent installation uses. But I think at the price, you get a nice transformer, nice case, nice inputs. Something to tinker with. . .just like the yugo or the adobe cars. . .LOL. What does the Modulus-286 weigh in at?

The Adobe Car (Vintage Saturday Night Live Commercial)

 

[tomchr]

What does the Modulus-286 weigh in at?

Depends what chassis you put it in. The Modulus-286 is a module for DIY amp builders and OEMs. The module itself weighs about 100 g maybe 125 g.

You can build it with a traditional mains transformer-based supply if you wish. I offer an audio grade one on my website. I often build it with an SMPS because the SMPS offers better performance, lower weight, and lower cost.

I discontinued the kit shown in Post #1 many moons ago. I now offer a much nicer chassis. It's larger and, thus, heavier. Its surface finish is much nicer than the older Kit chassis. And it costs real money - both for you and for me.

In than configuration it weighs about 5 kg. If you build it with a traditional supply as shown below, the weight jumps to around 7 kg as I recall.

Tom

 

[pma]

Both look well designed.

 

[tomchr]

Thank you.

I can't buy the chassis for the cost of that Rane amp, so I have to charge real money for them. If people pay real money, they expect a real product to be the result of their DIY efforts. So that's what I deliver. A chassis for a DIY build that looks like it belongs in a high-end hifi show.

Tom

 

[Ground Noise Industries]

Thank you.

I can't buy the chassis for the cost of that Rane amp, so I have to charge real money for them. If people pay real money, they expect a real product to be the result of their DIY efforts. So that's what I deliver. A chassis for a DIY build that looks like it belongs in a high-end hifi show.

Tom

The chassis makes people ask, "What is that?" Then they get educated.

Mine (headphone amp) are just a hard board box designed to keep out dust and fingers. As simple as a coffin should be.

 

[brunes]

Should be noted that the communication, support and knowledge of Tom is epic!
You won't get that from large/ commercial brands...

 

[restorer-john]

Thank you.

I can't buy the chassis for the cost of that Rane amp, so I have to charge real money for them. If people pay real money, they expect a real product to be the result of their DIY efforts. So that's what I deliver. A chassis for a DIY build that looks like it belongs in a high-end hifi show.

Tom

Put down that impact driver Tom.

 

[tomchr]

Good Lord. People really will comment on everything. Good thing it's a DIY project. You can do with the screws as you please.

Tom

 

[LionIT]

I think a limiting factor of the Modulus project is the choice of PSU.
I am using the Connex in mine, but apart from that it seems to me that only a few Meanwells and Mornsun remain.
There is also the Micro-audio, but it starts from 600W which seems excessive to me.
Sure, there are hundreds unregulated options but I think an SMPS is always preferable.
@tomchr have you ever thought about designing and providing your PSU?

 

[tomchr]

I agree that the Connex SMPS300RE used in the Kit shown in Post #1 is the limiting factor. That's also why the Kit amp was able to deliver 125 W into 4 Ω on one channel but only 100 W into 4 Ω with both channels driven. Of course, this is inconsequential for music reproduction as the signal peaks are short lived and not perfectly correlated between left and right channels, but it matters for sine wave testing.

The SMPS300REh is a bit better, but the assembly quality isn't super great. I've received a couple where the spade terminals for the output weren't soldered properly. For those I delivered with the Kit, I went through and soldered them all. That's not satisfactory for a commercial product.

The supplies from Micro-Audio look very good. I have one on my bench. It seems very well made. I also like that Micro-Audio certifies their supplies with respect to EMC, electrical safety, and such. Sami runs a good business.

There are other options: A pair of Mean Well LOP-300-36 would be well suited for a Modulus-286 stereo amp. I would think that the LOP-300-30 would be great for a Modulus-86 amp. LOP-600-36 for the Modulus-686.

I haven't touched SMPS design since college and designing an SMPS for mains use is not trivial. In fact, I did that for my honours project in college. I'm sure I could get back up to speed on this topic. I'm also sure I could figure out the various electrical safety standards, EMC standards, and whatnot, but designing and certifying a power supply would be a massive research project with very little return on investment. The options from Mean Well are fantastic.

Tom

 

[pma]

LOP-300 series looks good. Those Mean Well supplies have both line and load regulation, which is great. I am using two smaller RS-100-24 units in a lower power, 2x60W amp. They are working well and are reliable.

 

[tomchr]

I've been impressed with the Mean Well products so far. They meet their specs and they're certified to a plethora of standards.

Tom

 

[brunes]

I think a limiting factor of the Modulus project is the choice of PSU.
I am using the Connex in mine, but apart from that it seems to me that only a few Meanwells and Mornsun remain.
There is also the Micro-audio, but it starts from 600W which seems excessive to me.
Sure, there are hundreds unregulated options but I think an SMPS is always preferable.
@tomchr have you ever thought about designing and providing your PSU?

What is the benefit of a SMPS vs torroidal out of interest?

 

[tomchr]

Most SMPSes are regulated. The Hypex SMPS1200 is a noteworthy exception to this. A regulated supply will provide the same output voltage (almost) regardless of the load current. So with a regulated SMPS you get more consistent performance. This typically shows as a few extra watt before the amp starts to clip.

SMPSes are lighter, so the shipping cost is lower. They're also now often lower cost than a "linear" power supply (which isn't linear at all).

But some still favour the traditional supplies. Likely because of nostalgia but also because they are heavier. Males judge heavier equipment as being of higher quality. That's been established by consumer psychology experiments. And high-end audio customers are pretty darn close to 100% male.

Note, though, that most SMPSes will have some switching hash on their outputs. This can be filtered out. The switching frequency is well above audible, so the hash isn't audible, but it can show up in audio measurements where it will show as degraded THD+N when the measurement bandwidth is extended past the audio band. Also, some amplifiers have rather poor power supply rejection ratio (PSRR) and are, thus, more sensitive to power supply hash. One of the many advantages of the Modulus architecture is that it makes the amplifier power supply agnostic due to its very high PSRR.

Tom