I received the Hypex parts for the first stage of the project.
Various leads and a remote control
The input board has plenty of connections.
I checked the Main/Aux output on the SMPS's, plus the voltage on the Standby Module and all were as expected. I wired it up to explore the menu set up and set the volume to minimum, prior to connecting to the Amp and testing the Audio.
I downloaded the latest firmware/filter software, created a basic filter set on the laptop and uploaded it.
I'm only using the auxiliary output from one of the SMPS's at present, to power the DSP. They are really meant for powering the Hypex Amp modules, to be fitted in stage 2 of the build, but I needed to test the pin out for the DSP standby signal, that puts them and the Amp modules to sleep. There are many ways of wiring these boards, better to understand how the plumbing works before fitting it all into the case.
Now I need to disconnect the analogue and passive crossovers from my speakers and add a series capacitor to protect the ribbon tweeter. I should then be ready to insert the temporary Nakamichi amplifier.
I got everything swapped over, ran it in for a day but was very disappointed by the sound quality, light in the bass, soft and woolly mid range, not good at all. Double checked everything, nothing wrong with the way things were connected or with the filters I created?
I re-read some of the threads on the diyaudio forum and folks were very pleased with the sound, so something wasn't right. I thought about the power supply, I was using the Aux output from one of their amplifier SMPS, which is an option suggested by Hypex. I thought about buying their dedicated SMPS for the DLCP which outputs the main dual rail voltage but also produces the single 8v standby voltage. I was very surprised when I read the spec sheet for this supply:
"This switch mode power supply is specially designed to be used in mixed signal applications such as DSP and audio applications requiring a single low voltage output for powering the digital parts of the circuit and both a positive and negative output rail for powering the analogue circuitry."
So the single 8v supply may not be just for the standby function, I had used a cheap switching supply about 25x35mm for this, you can see it front left in the picture above, as I presumed from the blurb, that it was not in the audio path. I decided to buy the dedicated supply.
Didn't take long to swap out the Amp SMPS for the dedicated supply.
What a difference, instantly more drive, solidity in the bass and crisper more transparent mid range, this is more like it.
Still slightly better with digital rather than analogue sources, but not a lot in it, much much better.
Hypex are known for minimal instructions, you don't actually get any and have to use the sparse information from the on-line spec sheets, which are great at detailing pin outs etc, but say little about what options you have if straying from using an all hypex solution, (PSU etc) your pretty much on your own. But to be fair, I have found them good at answering emailed questions on my build.
I need to optimize the sound of the Hypex DLCP before making my final choice of using Digital or Analogue. I'm taking my time over this as there is a lot to take in and learn. If your drivers are reasonably well matched, its easy to get a fairly good sound out of some basic filters quickly thrown together. To get the best out of your driver combination, is another matter and I've gone about as far as I can without measuring what is happening.
To this end, I have just purchased a Focusrite 2i2 USB interface and I'm waiting on a Dayton EMM-6 mic from the States. The mic has been purchased from and calibrated by Cross-Spectrum Labs, to be accurate from 5Hz to 25kHz. All this technical malarkey is a big sideways step from enjoying my music, but it's my hobby and a necessary evil if I want to build something that will compete with commercial offerings well beyond my price point.
One of the best features of the Hypex system, is that their DSP software is also the analysis software and it all works together in a single interface.
The easiest way of explaining this principle is with a screen shot from their very minimal manual.
The Red trace is the measured and imported response, you can work on an individual channel (driver) or the summed response for all channels (drivers).
To add a filter, you click on the approximate position you want it (Green Dot), then in the main menu select the type of filter and adjust the frequency and +/- dB figures etc in the dialog boxes, to the exact ones required. This creates a filter and it's displayed as the Cyan trace. The Orange trace is the programs prediction of how this filter will effect the imported response. Users have reported a very similar measured response, to that which was predicted. You can add multiple filters/adjust/delete as required, it's quite a nice interface and fairly easy to pick up, through trial and error.
It may not have all the bells and whistles of something as powerful as REW, no waterfall display for instance, but you do get Magnitude, Impulse and Step screens to work with. It's aimed at the DIY market, not at Audio Engineers and its feature set and interface have been designed with that in mind.
It's a useful tool, but Hypex make the point that they expect you to have a basic understanding of some of the audio science behind it all. I would add that, just as owning a CAD system will not automatically turn you into a mechanical engineer, using this type of software does not make you an audio engineer, with the knowledge of how to interpret and respond to the displayed results. That said, with a bit of reading, from their manual and around the forums, you can gain enough knowledge to produce very satisfying results.
I need to put some of this to use now.