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Modulus-686: 380W (4Ω); 220W (8Ω) Balanced Composite Power Amp with extremely low THD

Is there a particular reason you're choosing to single me out?
No, not at all, I was just reading it on the sideline and felt like responding since I think I know a thing or two about it.
I don't follow all topics and discussions here.

In fact, I don't think anyone is single you out, so I don't follow the emotional reaction here?
This is just a general conversation that also happens to involve your project.
I personally think it more than fair that people have question about safety of a product?
That could be ANY product or project from anyone.

If people have similar questions about the vendors/products you just mentioned, they should ask in those topics accordingly.
So I actually totally agree with you on that! :)

I am making every effort to ensure that my products are safe and that they play well with others, i.e., are EMC compliant.
Which is great!
Just be aware that something is only officially compliant as soon as you can show people that you went through all the tests and got a official certificate.

Otherwise I would call it EMC prepared ready or something.
Duly noted. But I can still use the term 'certified'. After all, I can self-certify.

I don't follow the emotional reaction here?
Really? You don't understand why I would react strongly when you launch a direct attack on my business by spreading fear, uncertainty, and doubt about my products and, thereby, threaten my only source of income and everything I have worked for? Really?! You really don't understand that?

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you launch a direct attack on my business by spreading fear,
I don't see the attack, so no sorry?

If that comes across that way, my sincere apologies.

I also never spread fear, in fact I put it even into context that what you're doing is fine as long as you're clear and transparant about it.
Other people did spread fear, which I do agree is not the right way, hence I decided to respond initially. :)
Mostly here to help you as well as everyone else!
Continuing to argue well after the conversation has run its course comes across as an attack. At least it does for me. I've stated several times today alone that I considered the part of the conversation that pertains to certification and compliance to be done. What are you looking to gain from forcing it to continue? I've already made it painfully clear that I have double-checked the relevant standards and regulations for three key markets, including the market you're familiar with. I don't operate in a vacuum. I have had back-channel conversations with experts in the field all week. So I firmly believe I have done my due diligence here.

I have also made it clear that I see three options for going forward with this. After all electrical safety and EMC are important to me.
  1. One approach is to have everything certified by a compliance lab. The cost of this is in the range of several thousand to possibly tens of thousands of dollars per product. That would destroy my business and consume all my retirement savings. So that's a non-starter. Sorry. Financial suicide is just not my thing.
  2. Another approach is to buy $5-6k worth of test equipment so I can measure whether the 2-3 products I have that would require EMC certification have a fighting chance of passing EMC compliance testing. This is commonly known as pre-compliance testing. It carries no weight as far as compliance goes but passing a pre-compliance test increases the odds that the equipment will pass if submitted for testing. If the circuits are, say, 10 dB better than required I'd feel pretty comfortable slapping a CE mark on them and calling it good. This is known as self-certification.
  3. A third approach is to do nothing. That's what you endorse below.
So what @tomchr is doing, is the correct way, no marking at all means, not compliant to any standards.
Aka, it comes as is, and he's not liable for anything, SINCE it's not compliant.
As long as he makes sure that people are aware of that, that's 100% fine.
I already have a safety disclaimer in the design documentation. Perhaps I should add an EMC disclaimer for the few products where that's relevant.

I will admit that test equipment has been a long-term fetish interest of mine so there's a real good chance that option 2 will happen. If nothing else, showing some pre-compliance testing of my products would make for a really cool YouTube video and good marketing that could help me stand taller than the rest. Then again $5-6k is a lot of money to spend in particular considering the value it provides (none, really - certainly nothing tangible of value).

I haven't had to worry too much about EMC in the past - at least not as far as unintentional radiation goes - as few of my products have oscillators in them. But that could change should I decide to develop a DAC for example. There's a big difference between using a certified SMPS brick that runs at 50-100 kHz and designing a DAC that would have 25-30 MHz running on the board (connected to USB that runs at some ungodly speed).

If Option #2 happens it will not happen overnight. In part because the lead time on the equipment I need is weeks-to-months. That is another reason I consider the conversation regarding certification and compliance to be done, at least for now.

@b_force if you are concerned about my approach here or you would like me to consider a specific standard or regulation you are always welcome to toss me a PM. You and I may find that conversation interesting or stimulating, but I doubt anyone else here will. Most are here because they're interested in DIY audio. They didn't come for the Standards & Certificates Lecture Series. :)

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Will do, I just got a PM from someone else as well.
I think it is an interesting topic, not because it's sexy and makes us audio nerds happy, but it's just good to know for anyone who would like to transform his/her idea into something more serious.
It's part of my daily job, and even with someone on it fulltime, it still drives me crazy :D :D

Btw, I wasn't concerned about your approach, but I just wanted to put some more perspective and context into the conversation, since the narrative seem to be very black and white.
I wasn't aware of anything before, so if things are said already, my apologies :)

Also, I wasn't endorsing anything (in fact, the opposite), but that is probably miscommunication :)
People should make up their own mind.

Best advice I always give is that it's ALL about transparency!
I do prefer playing with open cards. I stand behind my products and I have nothing to hide. If I don't share it's because I don't have data to share.

And I do agree that it's an interesting topic. However, it would be better served in its own thread. After all, the regulations apply to all products and not just my products. I'm happy to participate to the extent my time allows should you choose to start your own thread on the topic of certification and regulations.

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It seems we're veering off into the weeds again. Let's get back to the point of this thread, namely Tom's power amp module. If you want to discuss (a) how to ensure that your DIY amp is safely constructed or (b) the rules and regulations for such or (c) whether or not many makers of audio electronic product comply with such rules/regs and how (or how not), another thread would be appropriate.
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@tomchr, I am not shooting at you or your company. I have no reason for that, because you're not doing any harm to me. Quite the opposite, as I am enjoying the amps I built from your kits a while ago.

All I am saying is that the European Union website is crystal clear by saying "Many products require CE marking before they can be sold in the EU." (see link in my previous post). Your fully built amps belong to the product category that needs a CE mark, but they do not have a CE mark. This means it's not allowed to sell them in the EU. Again, I am not shooting at you or your company -- my intention is rather to let you know about this potential issue, and that you should be careful to avoid unnecessary issues.

Since you did go to great lengths to make your products safe, you could simply follow the steps for self certification and then slap the CE mark on your fully built amps. As I read the europa.eu website, it's just a matter of documenting your measures of making your amps comply with the CE regulations, and keep a record of those documents in your drawers.

I don't know if and how XRK, Tubelab, Aspen/AKSA or Twisted Pear sell fully-built devices that need a CE marking to allow selling them in the EU. Pass Labs certainly do, and my Pass preamp does have the CE marking.
Since you did go to great lengths to make your products safe, you could simply follow the steps for self certification and then slap the CE mark on your fully built amps. As I read the europa.eu website, it's just a matter of documenting your measures of making your amps comply with the CE regulations, and keep a record of those documents in your drawers.
Yep. Just. As in just a matter of blowing $5-6k on test equipment, etc. as I wrote in Post #1664 just a few posts back. Cost aside that's the most desirable option in my view and I may just end up doing that. Meanwhile, a just as valid option is to simply not sell completed products into the EU.

Can we put this one to bed now?

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This means it's not allowed to sell them in the EU.
It's not a consumer product, it's a diy development prototype board ;)

I am sorry, but I am gonna be with Tom on this one.
There a hundreds of websites selling little electronics boards all imported from China. Many of these companies are based within the EU and 99.8% of these products are not CE compliant nor have CE markings.

A very good example is a known French webshop that sells audio amplifier PCB's and kits. They even sell SMPS boards.

So I am missing the point here completely as well.
At a certain point it's being pedantic.
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Agreed. Pedantic is very apropos given what is now a beaten, bloodied, dead horse. :cuss: :headbash: :bawling:

Moving on PLEASE. It’s not like Tom is in an imbecile. He can read, digest and have an opinion. And after all, it’s HIS business. HIS risk. Further discussions should be sent via pm or started as a new thread as BrianL has already proposed.

Some of us would like to talk diyaudio as it pertains to the sonics of this great amplifier. I wait with baited breath on groovybassist’s review when he is good and ready.

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As a consumer who’s bought two fully built Neurochrome amps from Tom and both headphone amps from his TCA brand, I can honestly say electric safety or stray emissions has never once entered my mind.

Once you familiarize yourself with Tom’s engineering background, fanatical approach to PCB design/build and measurement focused development process, it’s easy to see he takes all of his products very seriously. I’ve had his products in house for several years and never had a single hiccup with any.

In fact, after seeing Tom’s examples of proper PCB design and soldering, I’m amazed at how awful the soldering and construction is on many commercial products. His stuff puts many commercial products to shame.
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In fact, after seeing Tom’s examples of proper PCB design and soldering, I’m amazed at how awful the soldering and construction is on many commercial products. His stuff puts many commercial products to shame.
Thank you. Yeah. I have a good assembly house. They cater to people who care about quality, including oil & gas (this is Calgary after all), aerospace, medical, etc. All the boards go through the same workflow and they have it set up to produce IPC-A-610 Class 3 quality. That's the standard commonly required for circuits that offer mission-critical operations in harsh environments where failures would be intolerable. Think automotive ECU, medical, military, etc.

So that's their standard workflow. All boards that go through that assembly house go through the same flow. The difference is in the inspections. I have my products inspected to IPC-A-610 Class 2. That's the category commonly used in applications where service disruptions are to be minimized. Think enterprise/data centre grade computer servers and that sort of thing.

I have a good working relationship with the owner of that assembly house. He and I were curious at one point to see what level of quality they actually deliver in my case. Obviously they deliver IPC-A-610 Class 2 because that's what I pay for and that's what they inspect to, but we decided to send a batch of ten Universal Buffers through the Class 3 inspection.
Of approximately 2500 solder joints only two (2) 'failed' the inspection. I.e., of 2500 solder connections, 2498 met IPC-A-610 Class 3 and two of them met IPC-A-610 Class 2. The two Class 2 joints had solder that covered 50 % of the height of the component pin (SOIC package). Class 3 requires that the solder coverage exceeds 50 %. So they were literally off by only a hair.

That's why my boards look good and perform well.

There are many inspections along the assembly process, by the way. If you're curious about the full workflow, have a look here: https://neurochrome.com/pages/the-north-american-advantage

Consumer electronics is often produced to IPC-A-610 Class 1. According to that standard a component can be almost all the way off the footprint. As long as there's a solder whisker that connects the component to the pads it'll pass inspection. Needless to say, such low quality wouldn't have a long life. And the stuff that comes out of many of the overseas outfits? It's really anybody's guess what standard they follow, if any.

I'm sure some will criticize the IPC-A-610 standard. That's fine. But ask yourself: When you buy those Chinese boards from that French outfit mentioned earlier (or ePay, AliBlahBlah, Bezos' Bookstore, etc.) do you honestly think you'll get better quality than what I offer? Or how about when you buy boards that have been manufactured in a frying pan instead of a reflow oven? Really. Think about it.

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I’ve had my Tom Christiansen built Safe-n-Sane Modulus-686 for a week now, so I figured I’d post some impressions here. For starters, the amp came very well packed by Tom and as is usual with his builds, was pristine - it presents itself as a fully commercial product, not something you’d associate with DIY build. As is also typical of Tom’s builds, it works perfectly - no weird clicks, clunks, pops, etc. and it’s utterly silent - mechanically and when trying to hear any hiss or noise from the speakers. It’s no secret that Tom’s designs are neutral and don’t emphasize any particular frequency bands - the 686 proudly carries on that tradition.

For reference, my listening comments below are on the following system:

Matrix Audio Element X > Neurochrome Modulus-686 > Philharmonic Audio BMR HT Towers; all cabling is from Benchmark Media Systems

I also have a Modulus-286 built by Tom, so the easiest thing to do is highlight where I think the 686 differentiates itself vs the 286 (an already amazing amp). Objectively, I know these differences shouldn’t really be audible, but to me, they’re very apparent.

The first is dynamics - the 686 definitely has more dynamic pop than the 286. With my speakers, the 286 can sound a bit polite or even restrained. The 686 clearly has more dynamic pop - the differences in loud/soft passages is wider with the 686 and transients definitely have more snap.

The second apparent difference is in the amount of information unearthed by the 686 vs the 286. The 686 uncovers every subtle nuance in a recording, allowing you to really hear the timbre of instruments and the subtle inflections in the human voice. It’s not that more detail is being thrust at you - it’s just uncovering more information that enhances the listening experience. As an example, in one tune I was listening to (can’t recall what it was) I knew there was a subtle conga part being played in the background when listening with the 286. With the 686, it suddenly became clear the body of the conga was metal vs wood - you can hear that deeply into a recording with the 686.

The third difference is in the bass. Deep bass passages that weren’t apparent on the 286 are clearly present on the 686. When you combine this with the improved dynamics and subtle detail retrieval mentioned above, the bass performance is much more satisfying to me.

In a nutshell, the 686 is built to a high standard, delivered to you with the same care by Tom and performs incredibly well - what more can you ask for? For those of us who can’t build these on our own, I can heartily recommend one of Tom’s builds. For those DIY’ers who can, the 686 is a great amp. This one will be a long term piece of my system.
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System pics for reference…


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