Linkwitz-Riley xover using Piano 2.1 ?

Ok, here goes… I have just a Rπ running the latest version of Volumino using the 3.5mm jack output just as a basic ‘proof of concept’ . I was going to run it with Allo’s DigiOne SPDIF feeding my Cambridge Audio DACMagic but then had the thought ‘Why not find a DAC for the π and cut out the middle man ?’ After having a good look and read I had kinda decided on Allo’s Piano 2.1 (with the Kali added later IF all works out). However, I have a couple of questions about the Piano 2.1 which Allo themselves seemed unable to answer ! What I wanted to know is what filter topology can the piano 2.1 support, i.e. can you set it up as a 24 DB/octave Linkwitz-Riley alignment crossover with a bit of EQ using the Linkwitz Transform for sealed sub’s ? The reply I had from was er, laughable ‘ we don’t make filters ‘ and ‘ask TI’. So, the anyone out there able to answer this for me or do I scrap this idea and go over to Mini DSP ?
Thank’s in advance for any constructive comments or guidance offered
Best regards

References (part 1and 2. Excellent audio based web site )

Hi Greyman,

Sorry but we don’t make filters . We suggest that you get the TI purepath software installed and try creating your specific filter on the pcm dac ic. You can see easily if you have enough processing power on the DSP.

Hello Allo,
I hate to be picky but this is taken from Allo’s Piano 2.1 page:
“We are using 2 DAC Ic’s PCM5142 with integrated DSP. The PurePath software from TI is available for download (registration required) and can be used to create specific FILTERS and other audio functions.” (my caps)
I have to be careful not to sound rude but I guess you don’t really understand my question.
Isn’t there any Piano 2.1 users that can add anythig to this or answer my question ?
Best regards


I think that Allo is saying in effect that if you want filters that are different from the ones that are available in Volumio, you will have to configure them yourself using the TI software. Getting hold of that is, I believe, a potentially lengthy and tedious process.

Also, I may add, your question is pretty “hard” to reply if one is not an expert of filters :wink:

Greyman , I understand the frustration , but we stand by the above. Yes its possible to use the TI purepath software to create specific filters. Purepath software is licensed by TI not allo. And yes I do understand the question , but I don’t know the answer. The easiest way to find an answer , will be to download the software , create your specific filter and Purepath will tell you if you have enough mips.

The DSP can take compute any topology including RL 24db but once you throw some EQ , the MIPS used are impossible to calculate unless you actually create the filter on your PC and software calculates requirements.


This thread at diyAudio might be of interest: … umio2.html

Thank you all for your replies especially Allo. That’s all I was after from them & sorry if I appeared blunt in my reply. I’ll be reading the various links when off work next.
I’ve built loads of ‘electronic crossovers’ over the years & when we first went to a tri amped system for a PA setup back in the late 70s it was a truly ear opening experience. However, I have no experience in doing the same in the digital domain and was only after a few pointers. Anyone interested in what can be achieved might want to have a look at the FIR -ward thinking articles here … -articles/
Sorry if this has gone a bit off topic.