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Old 23rd February 2015, 03:34 PM   #1
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Default Markaudio CHN70: What did I hear?

A recent project of is a pair of small bass reflex speaker cabinets for an old 4-wheel-drive pickup in which the previous speakers were trashed. I intend to use the cabinets on the floor on the passenger side, with the speakers in an up-firing arrangement. The necessary small size of the cabinets made a small driver also necessary. I chose the Markaudio CHN70, not only because it is inexpensive, but also because I have had previous experience with Markaudio drivers and like the sound they produce. The boxes were built with offcuts of plywood, which made certain compromises in box size necessary. I ended up with two boxes of 8.5 liters each, with rectangular speaker baffles of 8 inches by 16 inches. The driver center is at one-third of the length of the rectangle and centered on the width. The baffle edges are square (no bevels). The drivers received no break-in time.

To test the speakers, I placed them on a pair of old woofer boxes, the front baffles of which are each 27 inches high by 21 inches wide. This placed the centers of the CHN70s at 38 inches high, just below my seated ear level. The woofer boxes as well as the CHN70 boxes were toed in so the drivers were on axis with my ears. I cued up a stereo copy of the Beatles' "Sergeant Pepper's Lonely Hearts Club Band" to which I have listened for many years and know intimately. In this arrangement the CHN70s sounded far too hot in the upper midrange, so I then placed them on the floor in an up-firing position to audition them in the way that I intend to use them. I placed them in front of the toed-in woofer boxes with the CHN70 end of the rectangle pointed toward my seated listening position. The CHN70 drivers themselves were about 12 inches horizontally from the vertical panels of the woofer baffles. The centers of the woofer panels are about four feet from each other, and the CHN70 drivers were about three feet from each other. I was seated centrally between the speakers, with about three feet on a direct line between ear and driver.

Listening in this position, the upper midrange was tamed as I expected, since I was listening somewhat off axis. The bass improved also (no baffle step effect). These improvements acquired secondary importance for me, however, because with this arrangement I was surprised to discover that the speakers produced a phantom image that was centered in the prior on-axis position that I first used to audition the speakers. The sound did not come from near my right or left foot, but rather was coming from ear height at the left front and right front. I have never before heard this effect. I have heard of "holographic imaging", and perhaps it means other things to other people, but it is the best term I can produce to describe what I heard.

I considered possibilities as to the causes of this experience. I thought that perhaps the elevated upper midrange frequencies that I heard, to which the human ear is most sensitive, were reflecting off the vertical panels of the woofer baffles and were interfering with the direct sound of the CHN70 drivers, altering the phase. I also considered the room: it is a smallish room, rectangular in shape, 8 feet in width with 8 feet high ceiling. The center of the toed-in woofer boxes stand about 2 feet out from the back wall along the width of 8 feet. The CHN70 drivers were about 3 feet in front of the wall, and I sat facing this wall, perhaps 4 feet from it. The room is filled with diffusive elements such as shelves, books, and CDs, as well as some furniture. There is not much open floor space.

I don't know what, if anything, of value can be garnered from this experience, but I found it to be arrestingly interesting. I assume that others more knowledgeable than I have experienced this phenomenon, and perhaps even designed speakers using it. So, I am asking the experts: What did I hear?
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Old 23rd February 2015, 03:45 PM   #2
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I'm not an expert, but the same happens with any midbass even with LP @ 300hz, you can have them on floor firing normal like woofer not upward, and the stage is going to be in ear hight

That effect is good for Desktop if you don't have place for bigger box but you want it louder, just place widerangers on desk and midbass on floor under the table, some toe up would be benefit, but again it's not even near optimum.
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Old 23rd February 2015, 04:53 PM   #3
xrk971 is offline xrk971  United States
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They sound hot because they are hot. There is a +9dB square top plateau from 600Hz to 7kHz built into the design. More info on this and other 3 in and 4 in drivers here.
An Objective Comparison of 3in - 4in Class Full Range Drivers

Try measuring the response if you can.

Last edited by Moderation Team; 26th February 2015 at 10:59 AM. Reason: Restore original content.
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Old 24th February 2015, 12:47 AM   #4
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Hello Moderators,
Majerjack has already created the same thread in the Markaudio section which makes it a multiple.

xrk
Our on-baffle anechoic measurements/data are correct and were verified independently for/by the Japanese who contracted me to design this driver. Unlike you, they understand different testing set-ups produce different results for wide compliance drivers of the type Markaudio produces.

You’ve more than had your say. Its time to turn down your volume and stop turning your issue into a vendetta

Mark

Last edited by Moderation Team; 26th February 2015 at 10:59 AM. Reason: Restore to original for context.
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Old 24th February 2015, 01:07 AM   #5
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My post on this full range forum was done in an effort to discover what the possible reasons could be for the effect I experienced. My post on the Markaudio forum was done to share with others interested in the CHN70 the results of a quick and easy project and the favorable impressions I formed. I see the two posts as separate and distinct. I thought this full range post might draw more views than if it were put on the Markaudio forum, but if the Moderators think it would be more appropriate there, I have no objection. I only ask that the two posts are kept separate and unedited.
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Old 24th February 2015, 01:28 AM   #6
xrk971 is offline xrk971  United States
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MarkAudio,
If you read my thread it is aimed at objective data which has now been confirmed to be correct for the 6 other drivers tested and now for the CHN by someone on a Japanese website who posted the same +9dB plateau from 600Hz to 7kHz. I worked really hard to verify my findings and took more data at different settings as suggested by other users. I, and many others on this forum agree that all we ask for is for factory measurements to reflect the product sold. I bought the CHN70 in hopes of finding a new full range driver that suited my needs based on the spec sheet response. Unfortunately, it turned out to be very different than advertised. I have no vendetta nor do I wish ill will on you or your company, so you need to stop attacking the tools and the users when the problem is obviously not the measurement.
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Old 24th February 2015, 01:31 AM   #7
CLS is offline CLS  Taiwan
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Quote:
Originally Posted by markaudio View Post
Hello Moderators,
Majerjack has already created the same thread in the Markaudio section which makes it a multiple.

xrk
Our on-baffle anechoic measurements/data are correct and were verified independently for/by the Japanese who contracted me to design this driver. Unlike you, they understand different testing set-ups produce different results for wide compliance drivers of the type Markaudio produces.

You've more than had your say. Its time to turn down your volume and stop turing this issue into a vendetta.

Mark
Did I read this right?

Vendetta?

English is not my native language. Does this word have another meaning other than I found in the dictionary?
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Old 24th February 2015, 01:35 AM   #8
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I don't have a dog in this hunt. I ask the interested parties to not allow their dispute to spill over into this thread.
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Old 24th February 2015, 02:03 AM   #9
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Quote:
Originally Posted by xrk971 View Post
MarkAudio,
If you read my thread it is aimed at objective data which has now been confirmed to be correct for the 6 other drivers tested and now for the CHN by someone on a Japanese website who posted the same +9dB plateau from 600Hz to 7kHz. I worked really hard to verify my findings and took more data at different settings as suggested by other users. I, and many others on this forum agree that all we ask for is for factory measurements to reflect the product sold. I bought the CHN70 in hopes of finding a new full range driver that suited my needs based on the spec sheet response. Unfortunately, it turned out to be very different than advertised. I have no vendetta nor do I wish ill will on you or your company, so you need to stop attacking the tools and the users when the problem is obviously not the measurement.
We've both exchanged views between us on driver design/testing last year. You and I have conversed on the difference between testing which I felt was good at the time. You have to come to terms with the reality that for some driver products, where their operational design is mechanically complex, they will vary more when tested.

The Japanese web site to which you refer was part of the interaction for CHN between tests at that time (still going on). Hence why it refers the CHN's "character" and makes no negative comment about the driver itself. That site goes on to help end-users decide on box sizes and possible equalisation based on my early recommendations. Sadly google doesn't do justice to translation.

Its main reason why the CHN isn't published on the Markaudio's site......because its design and performance is open for input by Japan's forum members and Diyaudio forum members. It will go global once the collective evaluation is worked through. I realise you're treating my efforts as a commercial crime which is sad, as it undermines collaboration from the only driver who's willing to listen to end-users.

The guys in Japan talk to me without feeling the need to turn issues into a kick-in-the-pants session. Had you taken the time to email me, or message or post in the Markaudio section, the discourse would have been welcomed. We may not always agree, but you constantly forget that I'm not the "typical" manufacture. I do actually listen to what guys say and want. That's how the CHN got born. The "N" by the way stands for "Norio" (Nakajima san) Markaudio's Japan importer.

Now maybe we can get somewhere.


Mark
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Old 25th February 2015, 04:04 AM   #10
ra7 is offline ra7  United States
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Let's get technical, Mark.

1. Can you please explain why XRK's measurements of 6 out of 7 drivers match the specs provided by manufacturer's but do not match the published measurement of the CHN70? Also, his measurements match that of at least one more measurement published online.

2. If you are able to, can you redo a measurement of the CHN70 in your anechoic chamber and post a graph with a scale of 50 db and 5 db increments, comparable to the Vifa TC9 spec sheet?
http://www.parts-express.com/pedocs/...ifications.pdf

It is well known that with a calibrated mic and using software such as REW, HolmImpulse and by gating out reflections, quasi-anechoic measurements can be made in a home environment. Such measurements are highly relevant and valid. One look at the multi-way forum or the many other speaker development forums on the internet will show that many DIYers across the world are able to make such measurements. These quasi-anechoic measurements have been shown to match manufacturer published measurements on numerous occasions. The science behind the measurements and their interpretation has been well-established and several books have been written on the subject.
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