dspMusik crossover for Linkwitz LX521 interest

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HAL

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dspMusik crossover for Linkwitz LX521 interest
« on: 19 Jul 2016, 04:55 pm »
Since Linkwitz Labs has issued a challenge for a DSP crossover for the LX521 speakers and the dspMusik meets the criteria, this is the place to discuss interest. 

His specifications say it needs a 3-way speaker crossover and a passive 1-pole between the two mids at 1KHz.  It can be done as a 3-way or 4-way with the dspMusik for a total DSP solution, as long as the user has eight amplifier channels.  The crossover electrical spec is a 4th Order Linkwitz-Reilly HP and LP at 120Hz and 7KHz which is also easily done and a 1 pole HP at 1KHz for the two mids.

I have a demo HAL MS-3 and dspMusik system that can be tried for this application if there is interest.   It will come with the block diagram for the LX521 crossover for the user to load and then can use the MS-3 to playback music files from either USB or Ethernet accessible drives.

If there is no interest, will not bother with the crossover design, so this is where to post interest. 


HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #1 on: 22 Jul 2016, 01:44 pm »
Ok, 53 views and no response.

Looks like no one is interested in a LX521 dspMusik digital crossover.  Hope whatever they come up with sounds this good. 


lowtech

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #2 on: 22 Jul 2016, 06:09 pm »
You realize "the challenge" is like three years old, right?

Perhaps you should accept it and validate that your DSP is up to the challenge.  All you need to do is buy the LX521 plans, build the speaker and program your DSP to match the official transfer curves supplied with your plans.

There are currently several viable DSP's in use that have been "approved" for use with the LX521 and are supported by the Linkwitz Lab community.

p.s. The current iteration of the LX521 is LX521.4 and it requires an 8-channel DSP (or 8-channels of DSP processing power using daisy-chained units).

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #3 on: 22 Jul 2016, 06:28 pm »
I have no doubt it is old.

I can replicate the response curves need without the speakers as I can use the specs to do the design.  He has put it all on his website.

The dspMusik has 8 channels of HiRez DAC outputs, so easily done.  Probably about 30 minutes of design time to replicate it and then measure it with CLIO.

I have no intention of building the speakers.  That is why I asked if someone were interested in a trial with their system.


Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #4 on: 23 Jul 2016, 06:51 pm »
I can evaluate it if you like.
I've already used four different (ASP and DSP) signal processor solutions with the LX521 and am intimately familiar with the requirements.
If your unit works well I will recommend it to the community.

Dave.

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #5 on: 23 Jul 2016, 07:28 pm »
Dave,

Since you are interested, I will build the software.

Where are you located?  I have to send a MS-3 Music Server with the dspMusik to use to program the dspMusik. 

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #6 on: 28 Jul 2016, 01:32 pm »
The LX521 crossover block diagram for the LX521 is complete.  This is using the high performance Linkwitz-Riley crossover block setup for a 3 way, 4th order L-R crossover.  Have added the single pole filter after the lower midrange for the upper midrange.

This is based off the electrical crossover parameters Linkwitz Labs has on the website for the LX521's.

Will be testing it with CLIO shortly to make sure I have the 3 way L-R and single pole crossover working as expected.


HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #7 on: 29 Jul 2016, 01:36 am »
Here is the best info I can find to the LX521 crossover design besides the specification description on the LL website.  I have no access to the crossover website, since I am not an owner.  It shows the different gains needed to get the correct acoustic summation for flat response.

If this is what it really implemented from the electrical network side, it is possible the specs that are being quoted are the acoustic crossover points.  If so will have to find a way to verify if these are the most recent design.   

Also the 1KHz spec is for a single pole filter, and the graph shows a L-R 2 pole. 

The design I have is based on the specs on the website, but this shows the difference.   Will see if I can find the correct version for the latest design.

Removed the image as for some reason Google is finding proprietary info.
« Last Edit: 29 Jul 2016, 02:21 pm by HAL »

Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #8 on: 29 Jul 2016, 03:21 pm »
There are two current versions of the LX521 system.  Both versions are four-way, but the earlier version utilized a passive crossover between the two midrange drivers. 
The later version is fully active for all four branches and also incorporates a different crossover/equalization/delay scheme.

You can start to see the challenge of the "Challenge" now eh?
As "lowtech" noted, you're way late to the party on this.  But if you feel your solution brings something to the table that others don't, then the community/me would certainly be interested.

Dave.

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #9 on: 29 Jul 2016, 03:32 pm »
Not really that hard with Audio Weaver and the dspMusik.  The challenge is finding the data needed, not in implementing it.

Last piece is the biquad coefficients for the woofer EQ.  Then it should be ready for CLIO measurements.

Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #10 on: 29 Jul 2016, 03:44 pm »
This is not a minimum-phase implementation.  You are aware of that, yes?

Dave.

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #11 on: 29 Jul 2016, 03:54 pm »
The crossover filter system will be the digital equivalent of what LL has posted.

The DAC's are minimum phase filters for reconstruction. 

Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #12 on: 29 Jul 2016, 03:58 pm »
What SL has posted on his public pages does not fully characterize the design.

And I'm not talking about the DAC's.  :)

It would probably be better if you just let me do the specific programming and you could just provide the general support regards the hardware implementation.

Dave.

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #13 on: 29 Jul 2016, 04:27 pm »
Davey,

The version one of the Audio Weaver crossover block diagram is done as far as I can go.  The only thing I did not add so far is the peak filter at 230Hz.  Easy enough to do, but not sure after trying that here with very poor results, why you would do it.

I will send the block diagram.  If you do not feel it is worth continuing, I will just bag the project.  If you do, will ship the MS-3 and dspMusik demo system for trials.  Everything uses the latest high performance filter designs from Danville for Audio Weaver.   

PM me your email address to send the file. 

Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #14 on: 5 Aug 2016, 03:58 pm »
Do you have remote volume capability on these units??

Dave.

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #15 on: 5 Aug 2016, 04:23 pm »
If you are running Audio Weaver for the dspMusik, the PC can do remote volume on any unit.  I use a wireless keyboard on the MS-3 to do the volume with the DAC 8 channel control.

johngore

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #16 on: 5 Aug 2016, 08:31 pm »
I want to voice support for this. Im planning to build an LXmini first for a smaller room and then if that goes well, a LX521 for a larger room. I imagine if you get this working for the LX521, then it should work for the mini?

Thanks for working on this.

HAL

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #17 on: 5 Aug 2016, 08:38 pm »
Would have to get the data needed for the LX-Mini as well to do the digital crossover.

All depends on how things go with the conversation about this version.

johngore

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #18 on: 6 Aug 2016, 05:44 am »
Yes, it will need a different filter set, but it's great to see these two technologies coming together.

Davey

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Re: dspMusik crossover for Linkwitz LX521 interest
« Reply #19 on: 6 Aug 2016, 01:47 pm »
How is volume controlled if the companion MS-3 PC is not connected?  The dspMusik (standalone) has no volume control capability??

Dave.