New build of Linkwitz LXMini

[somebodyelse]

With the BeoCreate you should be able to use the toslink out for subs if you want to add them later. Stepping up a level a pair of FusionAmps aren't much more expensive than good >4 channel DACs like the MOTU Ultralite Mk5. The sub for the Pluto (LXMini's predecessor) uses a much cheaper 10" Peerless if you need to cut costs.
https://www.linkwitzlab.com/Pluto/subwoofer.htm

 

[MCH]

Thanks. One question about the BeoCreate. I understand from the hifiberry website that it works with a pi attached running hifiberry's OS and DSP software (whatever that is). I understand then that it is either possible to input the necessary Linkwitz crossovers in that software OR that it is possible to run any other DSP software on the pi. Is this correct?

 

[mdsimon2]

Beocreate has a built-in ADAU151 DSP, so it is similar to miniDSP where the software is just a front end for programming that DSP. It has been a while since I looked at the Beocreate software but it is web based and seemed pretty flexible IIRC. My main complaint was that you used sliders to select values like frequency, Q, boost / cut, etc which was a bit of a pain.

I measured the response of various filters implemented on the Beocreate and compared to miniDSP, notably the shelf filters are definitely different between the two. Peaking filters and crossovers (I only tried second order) were the same. Like a miniDSP the Beocreate can accept biquad coefficients but the convention is a bit different with A1 and A2 swapped compared to miniDSP. Using a biquad is a good way to make sure you get the same shelf filter response as miniDSP.

If you do go with Beocreate let me know and I will fire it up again and can send you the necessary DSP settings.

Good point on the TOSLINK output @somebodyelse, definitely a really nice feature for daisy chaining an additional DSP for subs.

Michael

 

[somebodyelse]

The DSP is in hardware on the BeoCreate - once programmed you can operate it with the toslink input without the Pi attached. With the Pi attached you can use the Pi's I2S to send audio to be BeoCreate, but it's still limited to 2 channels so you can't do the crossover in DSP on the Pi. You could do the crossover in the hardware DSP and room correction in software on the Pi I suppose, but I think that would need a bit of home brewing as I don't think HifiBerryOS had an option for that last I looked. I may have missed it, or they may have added it since.

 

[MCH]

So.... 616 for the kit shipped + 220 beocreate w/180w psu + 84 license + 17 pi zero 2w.... everything readily available, right under 1000 for a cool project that with a bit of good luck plays music.... and the door open for the subs Fxxx! this is so tempting...

 

[Madjalapeno]

I have a BeoCreate in my office. I made a 'mini LX521' for fun with some speaker drivers I already had and I use it for nearfield listening.

The Hifiberry software is very nice to play with, and I got surprisingly good results for something I threw together on a weekend. It's worth getting just for learning how everything works. There is a noticeable hiss though when it starts streaming, but not bad enough for me to investigate too much.

 

[MCH]

BeoCreate owners, are these pins in the PCB line out connections one could use to feed a different amp if needed?
If yes, two questions: are they fixed level or variable with the volume from the app? If using the "line outs", is it possible to run the beocreate with nothing connected to the speaker terminals or is it necessary to connect some sort of load?
Sorry for asking, but can't find this information anywhere...

 

[mcdn]

The LXMinis work perfectly well close to the front wall - mine are 45cm from it. It does create a shallow dip in response centred on ~160Hz because the LXMinis are omnidirectional in that range, but this is easily corrected in the MiniDSP. As ever, the general rule is either to have your speakers close to the front wall or far away from it.

 

[mdsimon2]

BeoCreate owners, are these pins in the PCB line out connections one could use to feed a different amp if needed?
If yes, two questions: are they fixed level or variable with the volume from the app? If using the "line outs", is it possible to run the beocreate with nothing connected to the speaker terminals or is it necessary to connect some sort of load?
Sorry for asking, but can't find this information anywhere...

From this post -> https://support.hifiberry.com/hc/en...280917-Beocreate-4-Ch-Amp-with-analogue-Input sounds like they are differential DAC outputs for debugging. It doesn't sound like these are normal line level outputs and I imagine need some sort of amplification to be useful.

Michael

 

[MCH]

From this post -> https://support.hifiberry.com/hc/en...280917-Beocreate-4-Ch-Amp-with-analogue-Input sounds like they are differential DAC outputs for debugging. It doesn't sound like these are normal line level outputs and I imagine need some sort of amplification to be useful.

Michael

Thanks a lot, had not seen that. Hmm thats a bit of a bummer. I start to see pi/camilla > Asus sonar u7 (or similar) > old AVR OR 2/3 small amps (ala aiyima 07) the cheapest, most modular and versatile/upgradeable solution.

 

[MCH]

Hey @mdsimon2 (or others) I have seen you mentioning a few times that you implemented the linkwitz filters in camilladsp. Is this something one can do straight away with the data provided when you buy the license from Linkwitz or does it imply any sort of advanced knowledge, do some "translation" etc.
In few words, could a lazy newbie like me be able to do it? Thanks

 

[abdo123]

Hey @mdsimon2 (or others) I have seen you mentioning a few times that you implemented the linkwitz filters in camilladsp. Is this something one can do straight away with the data provided when you buy the license from Linkwitz or does it imply any sort of advanced knowledge, do some "translation" etc.
In few words, could a lazy newbie like me be able to do it? Thanks

Yes anyone can do it, the filters are provided once you purchase the plans.

 

[MCH]

Yes anyone can do it, the filters are provided once you purchase the plans.

Thanks, I understood initially that the filters provided were for the minidsp 2x4 platform only and wasn't sure they could be just used in camilla, hence my question, thanks!

 

[somebodyelse]

Yes anyone can do it, the filters are provided once you purchase the plans.

The plans I've got show filter parameters for minidsp as well as the desired response curve. It shouldn't be hard to use them with other DSP systems, but it's not always just a case of plugging the same settings in. The hypex filter designer uses different nomenclature for the filter slopes, and IIRC requires a two filter combination to achieve some that minidsp does in a single setting for example. I gather some packages have differences in Q definition. I haven't tried it with camilladsp but I don't think it would be too hard to translate from what I've seen.

 

[abdo123]

The plans I've got show filter parameters for minidsp as well as the desired response curve. It shouldn't be hard to use them with other DSP systems, but it's not always just a case of plugging the same settings in. The hypex filter designer uses different nomenclature for the filter slopes, and IIRC requires a two filter combination to achieve some that minidsp does in a single setting for example. I gather some packages have differences in Q definition. I haven't tried it with camilladsp but I don't think it would be too hard to translate from what I've seen.

The differences are in the realm of audiophile nervosa and are not really relevant.

 

[mdsimon2]

Hey @mdsimon2 (or others) I have seen you mentioning a few times that you implemented the linkwitz filters in camilladsp. Is this something one can do straight away with the data provided when you buy the license from Linkwitz or does it imply any sort of advanced knowledge, do some "translation" etc.
In few words, could a lazy newbie like me be able to do it? Thanks

Yes, it is very easy to translate. The LXmini uses LR2 high passes, LR2 low passes, high shelfs, low shelfs and peaking filters. All of these options exist in CamillaDSP and the response matches miniDSP exactly. I posted this in another thread but here is a comparison between miniDSP and CamillaDSP, they are identical. Note this is slightly different from the stock LXmini as I have subs and I reduced the high frequency peak at 15.8 kHz a bit.

You do need to be careful about DSP platforms, it seems particulary common to have different shelf filter definitions. I hesitate to call these differences pure audiophile nervosa as they can result in pretty significant deviation. For example the HifiBerry Beocreate has different shelf filter definitions and this results in a 1 dB response difference across a wide range, see below for the comparison.

As mentioned previously the Beocreate differences can be mitigated by using biquads for the shelf filters, see below.

Of course when in doubt measure!

Michael

 

[MCH]

Awesome as usual Michael, thanks again

 

[abdo123]

Yes, it is very easy to translate. The LXmini uses LR2 high passes, LR2 low passes, high shelfs, low shelfs and peaking filters. All of these options exist in CamillaDSP and the response matches miniDSP exactly. I posted this in another thread but here is a comparison between miniDSP and CamillaDSP, they are identical. Note this is slightly different from the stock LXmini as I have subs and I reduced the high frequency peak at 15.8 kHz a bit.

View attachment 184073

You do need to be careful about DSP platforms, it seems particulary common to have different shelf filter definitions. I hesitate to call these differences pure audiophile nervosa as they can result in pretty significant deviation. For example the HifiBerry Beocreate has different shelf filter definitions and this results in a 1 dB response difference across a wide range, see below for the comparison.

View attachment 184076

As mentioned previously the Beocreate differences can be mitigated by using biquads for the shelf filters, see below.

View attachment 184077

Of course when in doubt measure!

Michael

This might be copyrighted content, i would not share it if i were you.

 

[mdsimon2]

This might be copyrighted content, i would not share it if i were you.

The filter response is available from an open portion of Linkwitz Lab.

The-Magic-in-2-Channel-Sound

Of course the actual filter values are not provided and none of the construction techniques / dimensional information are defined.

Michael

 

[Pete Basel]

yes, however I think SL might have intentionally scrubbed somethings under the rug so he wouldn't embarrass his friend.

View attachment 131110

View attachment 131111

Did you bother to read the entire paper because you selectively show plots that support your claim,
but not the facts. Here is the next figure in that document where the measured final system response
is better with the ASP vs. DSP. I'm not saying that ASP is inherently better, it is certainly not as
flexible, but something does not seem right with the DSP adjustments above 5 KHz. I believe that
perhaps SL did not spatial average (even over a very small window) his first measurement and therefore
the first DSP compensation was for a very specific point in space, or there is driver to driver variation
that makes a general DSP correction curve above 5 KHz not practical.
Either way, that ASP curve should work just fine. Note that the bass boost is done with a peaked high
pass which has the advantage of removing very low frequency content that the speaker cannot handle.

Here's the remeasure (by SL) of the LX-Mini DSP vs. ASP, note the large peaks in the DSP system response above
10 KHz, and that the ASP has a flatter response. They are nearly identical (ignoring the low bass difference) up to
2 KHz and very well matched to 5K, the ASP is better higher up. The text included with the figure is by Nelson Pass: