An early Christmas present…

I generally make a point of buying myself a Christmas present every year and this year it came a little early 🙂 While I was looking for the Hypex Ncore module I wrote about a couple of weeks ago, a stereo ICEpower700AS2 popped up as well – so I bought that 🙂 This is going to be a “little brother” to my 700ASC-monoblocks but whereas the monoblocks (which I also hope to finish over this Xmas break) have added buffers and dual-input switching, this is just going to be made into a simple and no-frills power amp.

In contrast to the Ncore module the ICEpower amp has onboard heatsinks so mounting in a small(ish) enclosure should be fine – at least for home duties. As I already had a basic layout for both a bottom plate and a back panel, drawing them up was quite easy and the back panel order is already placed. The support PCB I did for the monos also works here which should mean that once I receive the back panel there should hopefully be very few blockers to wiring up the amp and getting it tested within the next weeks.

I have seen one comparison of the Ncore and the ICEpower module (although I can’t find the link at the moment) with the Ncore coming away as the clear winner, but I am looking forward to seeing if my own conclusions match that 🙂

(apologies for the poorly lit pictures, but winter in Scandinavia means no daylight when I get home from work :D)

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Encore?

A quiet last few weeks here – at least on the surface. Two reasons for that really: 1) With an Xmas-break looming on the horizon the pace at work is picking up a bit and 2) for quite a lot of projects I am in the annoying phase where lots of important work is done, but it doesn’t really look like you are getting closer to a finished product and so it’s not really worth showing here. If nothing else though, it’s nice to have a good pipeline for next year 😉

However, one thing there is always time for is to buy new projects for the shelves 😀 As regular readers will know I have made lots of ICEpower-based projects, but practically nothing with the various Hypex-modules. However, recently one of the new Ncore NC502MP modules came up on ebay and so I pounced on that. The module looks very nice but I need to test it for a while to check the sound (waiting for proper cables at the moment) and then I’ll decide on a suitable enclosure for it. The original goal was to built a custom high-power integrated amp, but I may end up going in a different direction and do a pure power amp instead. One deciding factor will definitely be whether mounting the module on a simple aluminium bottom plate proves to be enough heat sinking, because if the module has to be on a “real” heat sink, then all my current enclosure ideas are definitely out the window!

Soundwise, I still expect that the benchmark for the Ncore to beat (at least in class D) is going to be my trusty 125ASX-based stereo amp and the 700ASC-monos (which incidentally are also among the designs that are I am currently inching closer to completion…)

Slow-turning wheels….

I’ve been complaining about my pile of unfinished projects for the last few posts, but now I am at least at a stage where I can start to do something about it. The first step was of course to add cupboards where I can hide the mess ( 😃), but obviously the only really viable solution is start finishing up some of these projects, so I will try to get started on that during the Easter break – fingers crossed!.

Meanwhile, there are also other stuff to be worked on. One of the projects I did start warming up to has been my ICEpower700ASC-based amplifiers where I have managed to decide on an overall architecture. It’s going to be monoblock chassis with two switched inputs, provision for some form of buffering and an external trigger option. The ASC-board has a whole host of useful features and connections which it would be a shame not to exploit, but in order to avoid too many air wires I decided that a small breakout-board was in order. This will put the control signals and the aux power on more easily-accessible headers. Prototypes have been ordered! 🙂

Buffering isn’t 100% decided yet but since the 700ASC-module has a balanced input, the requirement was really for a fully-balanced buffer – ideally with Bal/SE conversion built-in. The obvious choice for that (and one which I haven’t really used before) is a fully-differential amplifier (FDA) such as the OPA1632. I’ve previously looked at this IC and done some sample board layouts, but nothing ever really came of it. This time, I’ve started from the schematic of AMBs excellent “Alpha24” design and started hacking it to suit my usage. The starting point for the board layout is one of my old ones, but significantly cleaned up compared to those previous experiments so hopefully everything works as it should (the OPA1632 is fairly high-speed and so board layout is a bit critical to get good performance and low noise).

I’ve also made rough mechanical sketches which are only really waiting for the boards etc. to become available so that the dimensions and placement of the various holes can be 100% finalised – paper mockups are a great way to do the initial prototyping though. The turnaround time for board deliveries from China seem to have slowed down a bit lately, but since all the Danish public holidays are basically in April and May there should be a chance to make some more progress when the boards do show 😀

New toys…

As per my last post I am in the process of moving (a lot of) DIY stuff out of my apartment, so what I should definitely not do is buy more things. However, sometimes an offer comes up that you just have to jump on 🙂

This time it was a set of unused ICEpower 700ASC-modules which is one of the ICEpower models I have not yet tried. They came up on a local classified page last week where I just spotted them by accident. The price was reasonable and since this is the ASC-version of the 700 with a few extra useful features then they should be quite versatile in use.

For now though, they are going on the shelf while I look for a suitable project for them (and move them to the new house 😀 ).

An ICEpower 50ASX amp – the easy way…

Some weeks ago a reader on the blog asked me some questions about various pre-made options for putting together a simple amplifier based on the ICEpower 50ASX2 module.

One of the options mentioned was to buy a case-kit for the module from Ghent Audio in China. I’ve seen pictures of these cases before and not only do they look quite good, they also come pre-drilled and silkscreened which for most DIY’ers is the hardest part of building stuff. I answered the questions as best I could without any hands-on experience to offer, but as I had an older black 50ASX-module left over I decided afterwards to get a case for myself and try them out.

After the usual waiting on shipping (which wasn’t actually that bad – app. 2.5 weeks), the case kit arrived. Everything is included, a power switch assembly, AC inlet, terminals etc and it seems to be decent quality all round. I didn’t buy the full cable kit, which would have made it even easier to assemble, but still it’s not too bad.

Putting together the basic kit with the module, feet, switch etc. ready for cabling only took around half an hour or so. If you look at the pictures I’ve made a few “adjustments” to the kit by using stainless screws and feet (the kit comes with black screws and matte silver feet), but otherwise it is as delivered and of course using the original parts would also have been just fine. The terminals are decent quality, but not the best I’ve seen. Also, the terminal holes are drilled too large (presumably to accommodate changing suppliers) which is slightly annoying but by no means a deal-breaker.

A bit more digging in the parts drawers revealed some suitable pre-made cables for signal and speakers – and a problem: my stock of JST connectors for the power connections has run out (or run away :-))

So yes, in conclusion this is definitely an easy way to build an amplifier (just as long as you ensure you get all the parts before you start 😉

Hypex UcD in progress…

It’s been quite some time since I have posted about a project that I have actually completed – and so I’m a little ashamed to say that this post won’t break that trend 🙂

It’s a class D power amplifier based on Hypex UcD400HG modules. As with many of my other projects, it started with a few leftover parts and some thoughts about what to make from them. In this case, it was the chassis and the “centrepiece” of the design, namely a gigantic 1000VA transformer. Trying to decide what to do with that lot soon led to some obvious choices:

  • It had to be class D because there was very little space for the actual amplifier and heat sinks once the transformer was installed 🙂
  • The “upstairs/downstairs” layout that I have mentioned before became a necessity to make use of the internal height of the chassis.
  • I wanted to reuse my PSU-boards because I already had spare PCBs, but they wouldn’t fit and so I had so make a smaller version.

I know Hypex has shifted to their newer N-Core technology and started building integrated modules with onboard SMPS, but the old UcD-modules still have a reputation as excellent amplifiers. The plan is to upgrade them with the Hypex HxR-regulators once I confirm that everything is working properly.

The “final problem” is how to provide heat sinking. I have my eyes on some pre-made heat sinks that should do the job, but they are from a supplier where I don’t normally order so costs are a bit higher than I would like. I might eventually break down just to get it over with, but in the mean time I have a couple of other options in mind as well 🙂

Class D experiments…

There are many class D technologies on the market at the moment, but one of the ones I haven’t tried (until now at least) is the International Rectifier “IRAUD7”-amps (IRF has been acquired by Infinion).

Consisting of the IRS2092 driver IC and various purpose-built FETs (many of them two FETs in a single package suitable for half-bridge designs), this is by most accounts a good-sounding and scalable class D technology. It’s also one of the few technologies where you can actually have a go at your own PCB layout if you want to. The schematics are available in IRFs published reference designs (here and here) and although making good PCB layouts for high-power switching electronics isn’t easy, it is actually possible to do.

Of course, when something is so easily available it tends to get exploited. It wasn’t long after IR introduced the designs before the market was flooded with several cheap clones, some using their own PCB layouts and some using IRs own Gerber files which are also published on the website. I had my eyes on some small (credit-card sized) boards to try for a while as they were really cheap (do an ebay-search for “IRS2092” and you’ll see 🙂 ), but eventually spotted this “luxury” version (at least based on appearance and observed parts quality) and fell in.

This build is the “low power” version with the IRFI4019 FET, but there’s also higher-power version with the IRFI4020 FET. Since the seller I bought from made a mix-up in ordering I actually ended up having a pair of each version, but I wanted to start with the low-power version. Then I might go dual-mono on the high-power boards later on if the sound quality proves it worthwhile 😀

The PSU consists of a 200VA transformer and a cheap supply PCB with 45mF capacitance per rail – mostly because that was what I had in my parts drawers. I’ve tried to keep the mechanics as simple as possible since I consider this build an experiment, but having the amp and PSU on a mounting plate simply makes everything much easier so I decided to “splurge” a little anyway :). The front panel is blank until I decide how the amp is going to be used.

Even though the pictures show the amplifiers uncabled (which they still are), I did manage some sneak listening on the modules and I am looking forward getting these into my main system for a proper test 🙂

 

50ASX BTL conversion (part 2)…

So, I’ve done some more testing on my BTL-converted 50ASX-modules…

As you can see, I’ve used a slightly less improvised test setup compared to last time (it looks worse than it is…). While I wouldn’t call what I have done “extensive testing” by any means, my gut feeling is that this works 🙂 It also ties in well with how the other ASX-modules work and some “insider knowledge” from years ago that I can still recall 🙂

Note and disclaimer: I would very much appreciate if someone else tried this to verify and maybe do more testing, however I will accept no responsibility for damage to property, people or pets (or anything else for that matter) if you find a problem – this is DIY after all 😀

You can of course hack this conversion anyway you like, but I opted for removing the old jumper altogether and soldering in a new one. If you do that, be advised that the ASX-board is four layers and soldered with lead-free solder, so it will take a bit more heat to reflow the joints than I am at least used to. If you use a soldering iron that is too small, you’ll just heat up the board and possibly damage it.

My suggested approach would be to cut the jumper on the top side of the board. Heat the solder joint from the bottom and pull out the jumper wire with small pliers. Then clean the remaining solder off the board with desoldering braid or (better yet) a vacuum desoldering station if you have access to one. Then solder in the new jumper in the BTL position. There isn’t much space to work on and you should be careful not to damage any of the (sometimes annoyingly) small SMD-components on either side of the board. Once the new jumper is in place, follow the wiring diagram for the BTL-version in the 50ASX data sheet/designer’s manual and you should be good to go.

Bear in mind that what you end up with isn’t a “real” balanced (= differential) amplifier, but two SE amps referenced to ground and driven with opposite phase input signals to produced a bridged output. As such, the input ground is still required in order for the amp to produce a correct signal on the output. I’ve found a good sketch here for LM3886 modules that should show the correct input wiring. Output on the ASX is taken from the P104 connector, so ignore what the sketch shows here (and of course the DC wiring is irrelevant as well).

If you do try this, let me know how you get on 😀

PS: Yeah and the picture is still crap – but don’t worry, the light should be better from around April onwards 😉

50asxbtltest-1

ICEpower 50ASX – SE to BTL conversion

I’ve recieved a few questions (and participated in a diyaudio discussion thread) about converting ICEpower 50ASX2 SE modules (which are fairly easy to get), into 50ASX BTL modules (which aren’t). I was pretty sure this could be done without component substitutions by simply desoldering the W401 jumper and resoldering it into the W400 position (marked BTL on the bottom of the board) but as I had no modules left, I couldn’t try it. Now I’ve managed to get my hands on some more modules and I’ve actually tried converting one of them and the good news are – I think it works!

I haven’t actually measured anything (not sure what to measure to be honest) but I get clean audio out on the BTL speaker connector (P104) and a very loud buzzing noise on the other output, so at least it isn’t running stereo anymore. No guarantees on anything yet though, but it’s definitely promising.

Oh, and don’t laugh at my improvised test setup, it is necessary because I don’t have a proper balanced source in the house at the moment and I couldn’t be bothered to crimp new cables just for testing 🙂 Incidentally, don’t laugh at the poor picture either – winter in Scandinavia means the days are so short that I can only take pictures in daylight during the weekend…

Next up is to convert a second module, build some better cables and try it “for real” in a stereo setup – hopefully this weekend 🙂

50asxbtl-1

Tripath TK2050 monos…

Well, it’s been a while since I posted a project that was actually finished…. and this one isn’t either 😀

It’s a pair of monoblock amplifiers based on Arjen Helder’s Tripath TK2050-boards. Arjen Helder is/was a Dutch guy living in China who around 5 years ago sold some great DIY boards based on the Tripath class D ICs. He’s probably mostly known in the DIY-community for the low-power TA2020-based amps, but he did make a few designs based on the more powerful TK2050 chipset as well. I bought a couple of the TA2020 boards when they were available because they were cheap and sounded great, but I managed to stay away from the TK2050 boards back then because I did not have anything to use them for (come to think of it, I don’t now either… 🙂 ).

Unfortunately I am nearly powerless to resist the temptation of an ebay-bargain so I snapped up this pair that I stumbled upon a couple of months ago without much hesitation. Originally, the plan was to mod the boards a bit replacing the stock capacitors, in/out connections etc. However, some of the traces seem to be very thin and as it isn’t possible to get a replacement board if I damage something I limited myself to just replacing the input caps.

The power supplies are a couple of Mean Well EPP-150s which were “left over” from my JLH-Evo build. They should be more or less spot-on for this when used in dual-mono mode and the small 4” x 2” size is an advantage as well.

The mechanics consist of pair of Chinese-made enclosures (selected because they were the right size for the job…) with custom rear-panels. I was going to use the stock rear panels, but a couple of stupid measurement-errors that I did not notice until after drilling made that a lost cause 😉

What’s missing is only really a few cables, but that isn’t my favourite part of a build and so I might save it for a long dark winter’s night instead 😉