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Olombo 4th February 2013 09:53 AM

FIR Filtering experiences
 
3 Attachment(s)
Hello!

I started this new thread to give you some of my impressions I recently had with active FIR filtering and to hear also some of your opinions and impressions. Furthermore you maybe have some good ideas how to further improve my system ;-)

Motivation:
Around 2 years ago I had the first contact with FIR filtered speakers. This have been PA Speakers by KS Audio. I was totally surprised what these PA speakers were able to deliver also at low loudness levels and so the decision was done quite fast: I must try out this for my home speakers, too.

My System:
Fortunately the setup of my home speaker System was already quite good fitting. I use a PC for playing the music and also movies for the beamer. The Audio output is 3x AES/EBU Signal coming from a cheap Marian Trace D4 Sound card (got for 90 Euro on ebay and works really well). As AES/EBU is compatible to Spdif a usual DAC is used for the subwoofer amp (T.amp Proline 3000). The Amp for mids and tweeters is a KS Audio TA4D which is able to receive AES/EBU Signals and has internal DAC. The speakers itself are maybe also a bit inspired by PA… ;-) 4x18” Beyma sub (18g40); 4x 10” mids (Beyma 10lw30?) and two Radion 950 tweeter. A discussion if this setup for a home cinema makes sense is obsolete….it makes no sense, but fun!

Which Software?
For the FIR filtering software several options can be found on the net. A non-commercial version DRC can be found. To be honest I had a look at it but after reading and reading the whole thing took too much time for me. Maybe I am too inpatient here this is surely a nice work regarding that the use is free! Maybe someone will create a nice GUI for that somewhen; then I will have a try again! From commercial products mostly about Acourate (AudioVero) and Audiolense (Juice HiFi) is talked about in forums. Both seem to be easy to use and always up to date as both developers are obviously really caring about their product. Both can be tried out in a demo Version. I do not want to judge that one of them is now better than the other as both make a really well engineered impression on me. I personally went then for Audiolense XO. The reason for that decision was basically that it is so damn simple to use!

Procedure and first tests:
There are several options how you can use Audiolense. The easiest way of all is just to go for the Plugin in Windows media player . As this is the fastest way for a first Impression I went for this one and installed the plugin while my active crossovers in a VST-Host program were left untouched as well as the formerly measured delays. In this configuration Audiloense only saw 2 channels without active X-over; comparable to passiv speaker setups. The procedure in Audiolense itself is very straight forward. Define Speaker Setup, Measure, Filter, Create Target; Create filter files. After done this one a new measurement with maybe new Target design is done within 2-3 minutes maximum. During measurement also different hints and recommendations can be found so to get a proper measurement is really not too difficult. At this first tests here I used a MM1 microphone but the microphone calibration data were not yet here. For this mic you can just ask for them at the manufacturer (did not know at this time). So this is one of the improvements I should do next time ;-)
Anyway after creating the filter in a few steps and insert into plugin first listening session was started. I could now end up in long explanations how nice this and this and the detail here and there is…. But nobody is interested in such explanations surely. The only thing that needs to be said at this point is, that you just get the most exact music reproduction according to you target curves that is possible. I just love it…. By the way my target curve for first try was really simple; I will also play with that next weeks but for a first test this was already ok (high frequencies a bit too sharp and loud maybe..)

Next steps:
The WMP plugin was only a first attempt. I usually never use this and instead use spotify for music. Actually I started now to set up a VST-Host Programm (Console by Art Teknika) with convolver.
As the convolver causes a small delay I also want to have the option not to use it as some streaming players from internet do not provide a audio/video delay. For movies played local with for example VLC this is no issue. So in the VST Program I have 2 settings now; one with and one without the convolver. The EQ is not used together with FIR filtering. As you can see on the pic at the moment the delays and crossovers are still done by hand and convolver plugin only is stereo. This I want to change in the next days to give Audiolense then access to all the single speakers. I assume this should bring another improvement together with finally the mic calibration file…!?

So it got a long post; basically just wanted to tell you FIR Filtering rocks! :-) And is also very easy to be done these days. So have you the same experiences or suggestions or questions?

Cu

krzys 5th February 2013 01:55 PM

DRC GUI
 
I personally use Audiolense basic 2.0. Very easy to set but no flexibility in filter construction. the filters sound nice . I know the XO version has more flexibility but cost a lot more and the help file is rather limited for understanding of all parameters.

There are two nice and easy GUI for DRC. I tried them but must admit that I never get good results with DRC. Try them by yourself and report

Digital Room Correction Designer Help

blogohl: Align2

Chris

Olombo 5th February 2013 08:43 PM

Hi

oh well never found theese.... sometimes I quit maybe searching too early ;-)

Looks interesting I will try them out for a A/B comparison!

But first now I will use the xo functions in Audiolense to see the difference between Audiolense filters including the xo and my "passix xo looking system" from viewpoint of audiolense.

For sure the xo version is a higher cost but in theory I assume you should be able to get a better behavior especially regarding phase in crossover points (at least between mids and highs). If this prooves to be right....next days will show :-)

cu
Ron

krzys 6th February 2013 05:44 PM

Yeah the audiolense XO version is smarter IF you use PC as crossover, I don't because of the long analogue cables needed (4 way system). I would love to see a downgarded version of the Audiolense without XO functions but it doesn't exist :(

Olombo 7th February 2013 06:10 AM

Hi,

yeah 4 -way System would be a mess with cabling; for my 3 ways I went for industrial multicore cables. They are with 8*1,5mm˛ and I use 2x2 for the LF speakers. Of course as they are not isolated against each other with single shield there may be interferences; but until now I did not recognise anything.

If you use the 2.0 what are you missing then from the big xo version?

What speakers you use? I do not own speakers which have a passive crossover but the comparison passiv/activ crossover would be interesting, too. Anyway too many interesting stuff exists so better focus ;-)

cu
Ron

soundcheck 7th February 2013 01:32 PM

I've been trying DRC over a couple of weeks last year once more (I tried it several times earlier). My intention was to get it done right - that time - after continously reading all those great stories about it.

To be honest.

I don't get along with the filter associated losses.

You win on one side. You loose on the other side. It'll always be a compromise.

People who tried rather simple conversions, such as different sample rate conversion tools, might have an idea what SRC can do to the sound.
And DRC is much worse than that.

I can live with DRC one an average system and a rather poor room.

On my main system it's a NoGo.

My 2 cents.

Enjoy.

krzys 7th February 2013 01:53 PM

Quote:

Originally Posted by Olombo (Post 3359340)
Hi,

yeah 4 -way System would be a mess with cabling; for my 3 ways I went for industrial multicore cables. They are with 8*1,5mm˛ and I use 2x2 for the LF speakers. Of course as they are not isolated against each other with single shield there may be interferences; but until now I did not recognise anything.
I was rather speaking about analogue signlal cables to amplifiers
If you use the 2.0 what are you missing then from the big xo version?
The 2.0 version offers three preset filters called less, default and more correction without any option and no time domain correction.

What speakers you use? I do not own speakers which have a passive crossover but the comparison passiv/activ crossover would be interesting, too. Anyway too many interesting stuff exists so better focus ;-)
I use DIY speakers: a 15" and a 10" cone drivers in closed boxes with med and tweeter horns and compression drivers, digital crossovers, source is PC via Logitec Touch
Chris
cu
Ron


Olombo 10th February 2013 04:41 PM

Hi,

@soundcheck: I will not claim that the whole FIR stuff is the holy grail of audio. Surely you can also find there disadvantages!
But for me it is a excellent tool and I will never give away again!

The SRC or filtering losses you mention I can not really judge; but for me the way to go fully digital was decided quite some time ago. This has many reasons....good crossovers with correct phasing, phasing within the single ways more linear with FIR; euqalize the speakers very convenient, easy to experiment, change "sound" and try out many different things. Of course a good build speaker without any digital part in it many people may like; I like more the possibilities of digital technology. And if you go for that a tool for FIR filtering should not be missed!


@krzys: I could not yet try out with digital xo. Too much work at the moment but I hope to do it the next weeks. And yes cabling is a mess at all.... ;-)

cu

Olombo 10th February 2013 04:45 PM

2 Attachment(s)
see some cabling and some "monsters"

cheers


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