OPERATION INFO: Flattening Markaudio driver response - diyAudio
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Old 19th October 2013, 08:38 AM   #1
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Default OPERATION INFO: Flattening Markaudio driver response

Hi Guys,
Having returned from my marathon trips across N. America and Japan, I've had the pleasure of meeting many good friends and listening to fab looking and sounding systems using Markaudio drivers. These systems have been expertly designed and built with an appreciation of the function/operation of Markaudio drivers.

However, there is a recurring issue that appears mostly in Europe that ignores the design function of Markaudio drivers in Full Range *Single Point Source Applications. That is the use of filters/crossovers/networks (mostly passive) to flatten the response of a Markaudio driver. In parts of West Europe, especially Germany, there appears to be body of opinion that the best response is flat, achieved by the application of various mostly passive filtering being applied regardless of the driver designer's work.

*1 pair of drivers in 1 pair of boxes

For the record:
Current Markaudio driver designs (CHR and Alpair models) aren't designed to be used with passive filters/crossovers/networks. Their cone structures are ultra low profile and ultra low mass. As many regular users of the latest crop of Markaudio drivers know, it makes them very sensitive to any input signal variation, passive filter component variances may adversely affect the feed to the drivers. For newer Markaudio end-users, its important to understand current Markaudio driver operational emittance design criteria. Regular users know why I purpose design a variable response in Markaudio drivers, so I'll only cover some of the basics here.

1: Rising high responses:
Rising higher range response in Markaudio drivers are there to deliver more listening choice and greater versatility in system room placement. Simply by angling the box (toeing in or toeing out) the driver's output assists in "fine tuning" the high range to better suit personal listening tastes and/or room characteristics. Take a look at the on-off axis drawing to give you a better view of the tuning potential by optimising the angle at which your system presents to you listening position.

2: Wide dispersion and central stereo imaging:
The current crop of drivers deploy ultra low profile cones. This section of the driver's power-train is specifically designed to operate within a wide on-off axis band (to 40 degrees off axis), giving users no acoustic audible losses in most typical off axis positioning. Take a look at the dispersion drawing, its designed to help gain appreciation of the current cone designs and their operation.

3: Earlier model drivers:
These drivers have more traditional profile cones mated to heavier power-trains. They are less emittance sensitive so maybe be better suited to using filters/crossovers/networks with careful application.

4: Active filtering:
New Markaudio drivers should be better suited to this type of application. Active software/control should provide lossless signal output while close control of specific bands of frequency output is achievable. This approach could well add another dimension to "fine tuning" a system. Several users and members have reported excellent results using computer software driven active filtering. Some experimentation may be needed.

Summary:
Current CHR and Alpair drivers are primarily designed as Full-Range Single Point Source emitters. To get the best results from these drivers, attention should applied to designing a system that is relatively simple, free of any passive filtering. Amplification should be relatively low power and have a clean output. Care should be take to select source material of a high quality.

Using Markaudio drivers in Multi-way applications is achievable while taking care to integrate the unit into the system. Quality crossover components usually yield better responses as part of the mixed emittance output.

For those wedded to the notion of "flat response" at any cost in a Single Point Source System, Markaudio and nearly all modern long(er) stroke Full-Range low-mass - high efficiency drivers aren't best suited to a passive filtered/control approach. In some instances, particular room conditions or a certain type of listening taste might be helped by applying a passive filter/crossover. However, this approach is specialised to a particular individual's need, requiring experimentation with an appreciation that the driver might be pushed out of it optimised output.

Thanks
Mark.
Attached Images
File Type: jpg on-off-axis.jpg (191.8 KB, 837 views)
File Type: jpg on-off-dispersion.jpg (230.9 KB, 821 views)

Last edited by markaudio; 23rd October 2013 at 11:21 AM.
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Old 19th October 2013, 11:47 AM   #2
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Hi Guys,
I've been asked in several emails today (and 2 phone calls); What is the ideal "off axis" position. This will vary according to room placement/characteristics, amplification and personal listening tastes.

Me personally, with my 55 year ears that can just about manage 15.5kHz (on a good day), I tend to place my systems close to "on axis" for most of my music. While in Tokyo last week, some of the younger users of Alpair 10P's demoing their systems at around 15 to 20 degrees off axis with very pleasing results, their hearing being much better than mine.

Once you've got your system up and running, I'd recommend experimenting with position/room placement, amplification and source. There are many variables influencing the system's output that time taken to "tweak" the whole set-up is always the best way to go.

For example, I've been recently testing a modified Lars & Ivan Hybrid mini-amp (see pic) using Alpair 10.3M's in slot boxes. This particular modified amp is quite mild so the boxes were toed-in a little more than usual to suit my high-range taste. Once I'm back on my Accuphase E-308, I'm toeing-out a few degrees to get the sound that suits my aging ears. Being prepared to "tweak" various parts of your system is important.

Lars & Ivan

Cheers
Mark.
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Last edited by markaudio; 19th October 2013 at 11:50 AM.
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Old 19th October 2013, 03:38 PM   #3
toobhed is offline toobhed  United States
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I'd like to add my experience in a go with passive BSC on an earlier version MarkAudio CHR-70s. After building the MarkAudio "Till-Double" speakers (dual 4R CHR 70's wired in series) I enjoyed listening without the optional BCS filter (0.50mH inductor with at 10W 4R resistor) specified in the plans.

But a few weeks ago, before bringing them to the BurningAmp fest, I decided to audition the BSC filter. To my ears and brain, it literally put a big wet blanket on the music.

Even though these were an earlier model of CHR's without the more-flattened profile, the BSC filter seemed to squish the music. I yanked the filter and am now listening to them as they were originally built...and feel better about a straight line from my amps to the drivers....

Mario
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Old 19th October 2013, 03:52 PM   #4
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Quote:
Originally Posted by toobhed View Post
I'd like to add my experience in a go with passive BSC on an earlier version MarkAudio CHR-70s. After building the MarkAudio "Till-Double" speakers (dual 4R CHR 70's wired in series) I enjoyed listening without the optional BCS filter (0.50mH inductor with at 10W 4R resistor) specified in the plans.

But a few weeks ago, before bringing them to the BurningAmp fest, I decided to audition the BSC filter. To my ears and brain, it literally put a big wet blanket on the music.

Even though these were an earlier model of CHR's without the more-flattened profile, the BSC filter seemed to squish the music. I yanked the filter and am now listening to them as they were originally built...and feel better about a straight line from my amps to the drivers....

Mario
Hi Mario (Guys),
Yes, the early double CHR driver design showed this filter option, agreed not to everyone's taste. Since that time, the CHR70 has moved on to the current third generation (25kHz at its top end et.al), best used filterless where practical. I've not had an opportunity to check using CHR70A Gen. 3's in tandem arrangements but I suspect my experience would be the same as yours, best filterless.

Thanks
Mark.
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Old 5th November 2013, 01:19 PM   #5
Henkjan is offline Henkjan  Netherlands
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Quote:
Originally Posted by markaudio View Post
....In parts of West Europe .....
amazing that nobody from our part of the world responded to this invitation from Mark Having designed a few boxes with Mark's drivers, I thought it would be good to add a few words from the "wood" side of things (designing boxes, not drivers).


The most important here is: use your ears, not your eyes.
How you enjoy your music is in the end down to the listening, not reading, not thinking, nor measuring.




Quote:
..... that the ... response is flat....
Quote:
.... the driver designer's work.....
These two fragments from Mark's opening statement can go together perfectly well, since the response of many Markaudio drivers is taylored such that a perfect neutral sound can be achieved without the need for any correction. Looking to my own designs, Conic with the gen1 Alpair10 and my Easter project 2010 with the Alpair 6p gen2 are good examples of this, both soundig neutral and measuring flat within a dB or so. Then why have I applied a correction filter in my Black beauty one might ask? Is there something with the CHR70A that is different than e.g. The Alpair6p? No, I just put it in a rather different box and that caused the ~5dB hump in the midrange, another box design would not have had this (due to differences in baffle step and edge diffraction).

So why did I choose to correct this with a passive correction, despite Mark's advise not to? Well, because to my ears the uncorrected box did not sound right, and I wanted to be able to use it on any system, so applying active correction was not an option. So I made the choice to apply correction, because the benefits to my ears outweighed the drawbacks. In other designs where the baffle step/diffraction hump was less (e.g. Easter project 2010 with the Alpair gen1 or the DesktopXL with the Mark designed EL70) but still audible, this choice would be more difficult.. I probably would be happy with either. And here come the beauty of DIY, every one can make his/her own choice here, based on ones own listening experience, musical taste, available equipment, etc. since we share the designs and backgrounds of the designs on the forum.


The most important here is: use your ears, not your eyes.
How you enjoy your music is in the end down to the listening, not reading, not thinking, nor measuring.
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Old 23rd November 2013, 07:04 AM   #6
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Quote:
Originally Posted by Henkjan View Post
amazing that nobody from our part of the world responded to this invitation from Mark Having designed a few boxes with Mark's drivers, I thought it would be good to add a few words from the "wood" side of things (designing boxes, not drivers).


So why did I choose to correct this with a passive correction, despite Mark's advise not to? Well, because to my ears the uncorrected box did not sound right.
Hello Henkjan, Guys,
I've no problem with guys tuning to suit their particular needs (as said in my first post). Every box-driver combination will likely have some quirks, that may or may not require adjustment depending on your objectives/needs. So long as you remain aware that filtering brings its own challenges when applied to ultra resonant sensitive drivers. In the case of passive filtering, care in component selection and network design, together with some experimentation is best.

Its important to understand my primary concern and my frustration with a certain minority. I'm referring to the few who spout the mantra that the only good response is a flat response, regardless of the driver and/or box designer's objectives, to the point where they completely ignore the design/function of the drivers and effectively mislead others.

There's plenty of posts explaining my design objectives, from frame damping, dispersion, power-train compliance, BSC compensation to on-off axis alignment, most members understand my efforts and have contributed to what has become a sort of "collective" effort from which everyone benefits. (How many other driver makers make the time to consult with you, the end users - You all know the answer).

I've no problem with the guys who believe-in and actively promote "flat" at any-cost, if they'd put their beliefs on the financial line and apply what they think is their expertise by designing and producing a truly flat-response full range driver. Then we can all experience more choice.

Thanks
Mark.

Last edited by markaudio; 23rd November 2013 at 07:31 AM.
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