One of the class D amp / SMPS module manufacturers I've been watching is the Spanish company, Coldamp. The owner/designer's name is Sergio Sanchez Moreno. Coldamp is one of the few companies that offer both an audio grade switching power supply (SMPS) and class D amplifier modules. The advantage to the SMPS, especially with a multichannel product, is the decreased weight and size. The challenge is to get them to sound as good as a linear supply. Sergio claimed Coldamp's SMPS sounded better than linear supplies and several DIY'ers from the diyAudio forum supported this claim. They also claimed the Coldamp class D amps were comparable to Hypex's highly regarded UCD amps. I don't think anyone was suggesting that they were better. Just different, but in a positive way. Several DIY'ers were satisfied with using a combination of the Hypex UCD amps with Coldamp's SMPS.
Anyhow, we are following the progress that all designers are making with both class D amps and SMPS development. Probably the most respected designer, Hypex's Bruno Putzey, was just written up in IEEE Spectrum magazine. You can read the online version of the article here.
I have also noticed that our blog regularly gets several hits from people doing a Google search for Coldamp. So obviously there is some interest in their products that seem to direct traffic to our blog. Since we have a few posts announcing Coldamp's products (see: Coldamp Plans to Offer 750W Class-D Amp Module), I felt obligated to update our readers with some disappointing news. The moderators of diyAudio have confirmed that Sergio was also signing on with another alias, named Pierre, claiming to be a happy Coldamp customer. It appears Sergio was using this alias on other websites as well. Most of the time, he was posting as just a very satisfied Coldamp user, sharing his experience with others looking for advice. As misleading as this may be, sometimes Pierre's posts were basic design and engineering questions directed to the experienced engineer's on the forum. These experienced engineers are particularly upset with this deception since they may have helped a potential competitor. They are also shocked that many of Pierre's questions were so basic that it demonstrated a fairly elementary level of expertise with the technology. One experienced designer/engineer named JohnW, stated, "Reading back though the "Questions" posted as Pierre; some are at such a basic fundamental level that they should never have been asked by a competent designer already SELLING SMPS!" Another diyAudio forum member, Eva responds, "The main problem is not how a designer gathers the knowledge, it's the fact that it's completely unfair to advertise and sell your very first prototypes as if they were state-of-the-art class D and SMPS, when they are full of hidden pitfalls that you don't know how to solve or don't know about at all because you still have a lot to learn."
Since this discovery, Sergio and his alias, Pierre have been banned from diyAudio's forums. I've also noticed that Coldamp's website is now down. So it appears they might be out of business. I think this is extremely unfortunate. Hopefully, Sergio and Coldamp can come straight and avoid a total collapse. Some of Coldamp's customers have posted in the diyAudio thread that they are happy with their purchases and felt the service and support from Coldamp has been very good. They work and apparently many people say they sound great. The problem is with how they learned to build class D and SMPS products, and are they really going to be safe and reliable over the long term?
Here's the diyAudio thread, in case you want to read more comments and judge for yourselves.