Simplifying ICEpower integrated amps…

Another old idea that I have resurrected and polished up a little 🙂

Many people (and many of my readers) want to build small integrated amplifiers with ready-made amplifier modules, e.g. the ICEpower ASX-series. It’s not that difficult as-is, but what if there was a single board that could help to convert an ICEpower ASX-module into a proper integrated amp? Well, there is now 😉

This module is basically made up of three parts bolted on to the same PCB.

– four single-ended inputs, switchable with relays
– a selector circuit that enables input switching with a single pushbutton (or with a rotary switch if you prefer)
– a power supply to utilise the on-board (but unregulated) AUX power supply on the ASX-modules as a power source

The only thing missing here is a pre-amp of some sort which must be a separate PCB, but can be powered from this board. The “Minipre” circuit was specifically made for this job but other circuits would certainly work as well – as long as they can run off +/-12VDC.

I made the first iteration of this board several years ago but managed to mess up the power supply arrangement so the original version didn’t really work (grr!). That I decided to get this circuit out of the drawer quite recently is no coincidence – I happened to find a single 50ASX module which I thought I had used already and so you can probably guess where this will eventually be going 😉

PS: While I prepare the project files for publication, let’s take the most obvious Q&As straight away 🙂

Q: Can it be used with other ICEpower modules, e.g. ASP/ASC-models?
A: Yes, but you’ll have to bypass the onboard power supply regulators etc. on the selector board as the ASP and ASC-modules have a regulated AUX-supply. Also, this board is intended for SE inputs and not balanced inputs (see below).

Q: Can the board be used as a standalone circuit or with other types of power amp modules?
A: Yes, but you’ll probably need a small unregulated dual power supply (15-18V) to power it. The current requirements will depend on which preamp-circuit you are using, but around 100-200 mA should be enough.

Q: Do I need to be able to program microcontrollers to build this?
A: No, the input switching is based on a 4017 counter IC so there is no code in this project at all.

Q: Can I use a rotary switch to select inputs?
A: Yes. Just connect the switch to the I/O header and omit the 4017 IC and its supporting components (a dedicated PCB for this is coming very soon).

Q: Can I stack two boards for balanced inputs?
A: Probably, although I haven’t tried it. Build a full “master” board and then a separate “slave” board without the PSU and selector components. Connect the I/O headers between master and slave for power/control and it should work (again, note the “should”-part…).

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