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Article: Advanced Acourate Digital XO Time Alignment Driver Linearization Walkthrough

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Hi chrisr, I am happy you found the article useful. Wrt SRC, I have tried several approaches/combinations, including using JRMC 19's SRC and Convolution engine. To my ears, all sounds transparent, and using null or difference testing, any measurable difference is below my auditory threshold. For myself, Acourate computes the filters and I use 48 kHz as the input sample rate as that is what I use in the LogSweep Recorder to measure. Cheers, Mitch

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Thanks Mitch for this help guide. Uli helped me setup my crossovers to integrate a pair of mono subs with my YG Anat III speakers. I previously integrated using external DSP crossover. Acourate is so much more transparent and precise with regard to the integration.

 

One thing that I think needs to be mentioned which hasn't been emphasized enough. Nobody should feel overwhelmed or intimidated in any way. This stuff may look complicated at first. However, Uli is unbelievably generous in offering assistance to his customers. He totally committed to making his customers' systems sound the best they can.

 

Also, I am now using a Lynx Hilo with the Acourate generated filters for subwoofer crossovers and full range correction. I've owned some mega dollar DACs used without DSP AND now I have a $2,500 Hilo coupled with the BEST DSP. There's no question that the latter is a FAR superior path to musical bliss than the former. The Hilo+Acourate is an awesome combo.

 

Michael.


THINK OUTSIDE THE BOX

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Michael, I am glad you found the guide useful. Uli has answered all of my technical and math questions, well above and beyond Acourate product support. I must say that Acourate is the most technically advanced and transparent audio DSP toolbox I have ever used/heard. Thanks to Uli for his most excellent software product and customer support.

 

The Lynx Hilo AD DA converter is vastly underrated for $2500. To my ears, one of the most transparent AD AND DA converter I have ever heard. According to one set of objective measurements, ranks #2 out of some 60 AD DA converters tested for transparency: Evaluating AD/DA loops by means of Audio Diffmaker

 

The Hilo’s ASIO/MME/DirectSound audio driver supports multi-client software applications. For example, one can be playing/streaming music in one application and record it in another at the same time. As a part time binaural recordist and musician, plus owning a turntable, I have yet to come across a routing scenario that the Hilo cannot support.

 

Another multi-client scenario is using REW to measure the acoustic output of ones speakers, while at the same time sending REW’s sweep signal via JRiver Media Center (ASIO input) with the Convolver engaged and loaded with Acourate FIR correction filters. No timing reference required. Use 48 kHz sample rate and ASIO drivers in both REW and JRMC. This is useful to confirm the performance of the corrected system and gives insight to what a good measurement looks like and correlates well with what one hears.

 

For example, aside from frequency response, time alignment/coherence is another important attribute for accurately/transparently reproducing recorded music to the listener’s ears. As mentioned in this Stereophile article, Measuring Loudspeakers, Part Two Page 2 | Stereophile.com one can use a step response measurement to show how time aligned or coherent ones speakers are. The Stereophile article points out what a good and not so good step response looks like, Measuring Loudspeakers, Part Two Page 3 | Stereophile.com. Mine look like this:

 

customspeakersstepreponse_zpsd739bd50.jpg

 

The acoustic step response of my system accurately tracks closely to the electrical input to the system. Also noted in the Stereophile article is that the step response is very hard for speaker systems to deal with and very few do it accurately. Personally, I feel a large audience of music lovers are missing out on this important aspect of music reproduction, which is just as audible in imaging as smooth frequency response is for tonality.

 

Enjoy the sound! Cheers, Mitch

Edited by mitchco

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Im sold on Acourate and what a great write up but I'm really interested in the value of the final D/A convertor. If I buy a Hi-end D/A converter will I hear significant improvements in play back; detail, air and many other artifacts while using Acourate software? is the software really that transparent?

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Thank you so much for putting together an easy to follow but detailed tutorial. I have owned Acourate for close to 5 years, but never really got around to doing a full active correction with it, till I read your detailed walk through.

 

I own a pair of Emerald Physics CS 2.3 speakers, which comes with a XO and EQ pre-configured in a Behringer Ultracurve box. I ditched that and did a 3 way XO, Linearised the drivers and time aligned running via a Prism Orpheus converter. All this was possible thanks to your guide.

 

The results are already so good, but for me, the fun has now begun :-). Hello to hours of endless tweaking :-)

 

Cheers,

Ronnie

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Hi Reginal25SF, sorry it took so long to reply, I have been away a while. Yes, Acourate is completely transparent in my opinion, both from a listening and measurement perspective. There are other testimonials to Acourate's transparency you will find in the first article: Computer Audiophile - Acourate Digital Room and Loudspeaker Correction Software Walkthrough

 

Hi Ronnie, that's awesome! I am glad you found the article useful. It makes a remarkable audible difference moving to a digital XO, driver linearized, and time aligned system. Amplitude and excess phase correction are icing on the cake.

 

Have you settled on a target response? Fyi, REW measurement software has recently implemented frequency dependent windowing and psychoacoustic smoothing that closely matches Acourate's analysis window. That means one can use REW to validate Acourate's FIR filters to see how closely they match the target response. Here is a REW measure of my right speaker at the listening position with the new psychoacoustic smoothing applied, overlaid with the target response I used in Acourate:

 

 

REW psy with target overaly.jpg

 

Virtually identical. Measurement signal path is REW digital output routed to JRiver ASIO (digital) line input using Lynx Hilo internal mixer, through JRiver’s 64 bit Convolution engine, hosting Acourate generated FIR filters containing 3 way digital XO, time alignment, amplitude and excess phase correction, out to 6 channels of Hilo DAC to 6 amps and speakers, right speaker to mic at listening positon, mic preamp, to ADC Hilo converter to REW digital input. I have not got around to driver linearization with a recently changed HF compression driver and waveguide. It is amazing to me the level of precision between the target and measured response given the number of transfer functions in the signal path :-)

 

It would be cool to see some measures of your Emerald Physics in REW if you get a chance.

 

Best regards, Mitch

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Mitch,

 

Im in awe of your efforts to put these tutorials together. I have a some questions about the procedures that I'd like to ask you about via phone if possible. I have acourate / acourate convolver driving an RME Babyface with a sat/sub setup. I'd really like to get few tips before I dive into the cal. I'm struggling with the time alignment procedure. Can you contact me at [email protected]?

 

Cheers...Doug

 

Hi Reginal25SF, sorry it took so long to reply, I have been away a while. Yes, Acourate is completely transparent in my opinion, both from a listening and measurement perspective. There are other testimonials to Acourate's transparency you will find in the first article: Computer Audiophile - Acourate Digital Room and Loudspeaker Correction Software Walkthrough

 

Hi Ronnie, that's awesome! I am glad you found the article useful. It makes a remarkable audible difference moving to a digital XO, driver linearized, and time aligned system. Amplitude and excess phase correction are icing on the cake.

 

Have you settled on a target response? Fyi, REW measurement software has recently implemented frequency dependent windowing and psychoacoustic smoothing that closely matches Acourate's analysis window. That means one can use REW to validate Acourate's FIR filters to see how closely they match the target response. Here is a REW measure of my right speaker at the listening position with the new psychoacoustic smoothing applied, overlaid with the target response I used in Acourate:

 

 

[ATTACH=CONFIG]21217[/ATTACH]

 

Virtually identical. Measurement signal path is REW digital output routed to JRiver ASIO (digital) line input using Lynx Hilo internal mixer, through JRiver’s 64 bit Convolution engine, hosting Acourate generated FIR filters containing 3 way digital XO, time alignment, amplitude and excess phase correction, out to 6 channels of Hilo DAC to 6 amps and speakers, right speaker to mic at listening positon, mic preamp, to ADC Hilo converter to REW digital input. I have not got around to driver linearization with a recently changed HF compression driver and waveguide. It is amazing to me the level of precision between the target and measured response given the number of transfer functions in the signal path :-)

 

It would be cool to see some measures of your Emerald Physics in REW if you get a chance.

 

Best regards, Mitch

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Hello Doug, thanks for your comments. I would suggest that you post your questions on the Acourate forum at https://groups.yahoo.com/neo/groups/acourate/info Based on my experience, you are likely to have more than one question :-)

 

Subs present a unique problem in the time domain as the peak of the waveform spans multiple samples, so what is considered the peak sample to time align the mains to? There are many knowledgeable people on the Acourate forum that have a sat/sub set up like yourself and can speak directly to time aligning that combo better than myself as I don't do subs. Time aligning subs to mains is worth the effort.

 

Best regards, Mitch

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Hi Mitch,

I can't figure out how to match the drivers levels in 3 ways setup, when recording the first logsweep ?

 


CD40s (3DLab) - EDEL NMR (Engineered) -or- DAPHILE (Q1900itx (Asrock) + LPS 100W (HDPLEX) + tX-USBexp (SOtM) - HYDRA-Z (Audiobyte) + LPS-1 (UpTone) - BLACK DRAGON (Audiobyte) - 2 x Ncore NC400 (Hypex) - M4 (P. E. Léon) - Cables: (Mapleshade, Audioprana, Nordost, Referenz1017, Pangea, Zavfino, Elecaudio, Tomanek) + FMC (TPlink) & NAS (OMV)

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HI @malarz I am not sure I understand the context... Assuming you have 6 DAC channels for a stereo 3- way active setup and outputting the DAC channels directly to the input of 6 channels of amplification? If so, does the DAC analog outputs have level control?s Or do your amplifiers have an input level controls? If so, then the idea is to trim the input level of each amplifier so that the logsweep produces a reasonably flat response or tilting downwards response as the frequency increases over the full range. Usually you run the woofer amp channel wide open as the woofer has the least sensitivity, then the midrange and then the tweeter needs the most level attenuation to be in line with the woofer and midrange levels... I may have misunderstood your question...?

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Hi Mitch,

Thank you very much for your reply.

You have perfectly understood my question.

So, before recording the "valid" logsweep, one need make several logsweeps and play with the amps inputs trim (or DACs output levels) in order to match the drivers levels.

That's clear.

Just curious, how could be possible to record the logsweep (with Acourate + XO) if one have the DACs and AMPs without the control of input/output levels ? 

For the playback, I assume it is no problem (player software can do it)

 


CD40s (3DLab) - EDEL NMR (Engineered) -or- DAPHILE (Q1900itx (Asrock) + LPS 100W (HDPLEX) + tX-USBexp (SOtM) - HYDRA-Z (Audiobyte) + LPS-1 (UpTone) - BLACK DRAGON (Audiobyte) - 2 x Ncore NC400 (Hypex) - M4 (P. E. Léon) - Cables: (Mapleshade, Audioprana, Nordost, Referenz1017, Pangea, Zavfino, Elecaudio, Tomanek) + FMC (TPlink) & NAS (OMV)

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Hi @malarz OK cool. You can control the sweep output level via Acourate. You can also insert a passive preamp(s) between the DAC and amps or use line attenuators to the mid and tweeter amps. You can also passively attenuate the drivers with pads (or L-Pad's) but not the best approach, but if no other way, then...

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Thanks a lot Mitch, great advice as usual ☺️

 


CD40s (3DLab) - EDEL NMR (Engineered) -or- DAPHILE (Q1900itx (Asrock) + LPS 100W (HDPLEX) + tX-USBexp (SOtM) - HYDRA-Z (Audiobyte) + LPS-1 (UpTone) - BLACK DRAGON (Audiobyte) - 2 x Ncore NC400 (Hypex) - M4 (P. E. Léon) - Cables: (Mapleshade, Audioprana, Nordost, Referenz1017, Pangea, Zavfino, Elecaudio, Tomanek) + FMC (TPlink) & NAS (OMV)

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