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Old 30th July 2014, 12:15 AM   #1
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Default New Driver: CHN70

Hi Guys,
Several hundred Markaudio drivers are being transported today to Madisound's shipper's warehouse in Hong Kong. Later this week, they should load onto a cargo ship bound for the USA.

So its a good time to talk about the all-new CHN-70 that's coming your way. The development of this driver came about at a meeting in Tokyo coffee house with Koizumi, our largest dealer in Chiba prefecture. Entry level Full-range driver prices have increased significantly inside Japan during the last 2 years, so I was tasked with challenge to produce a unit which would help to reverse this trend.

I was asked to maintain Markaudio's sound character but also create a drive unit thats easy to surface mount, all at a more modest price. This posed a real design challenge, so I'll go through the various components to shed more light.

Frame: To meet the Japan target price, I had to contemplate the un-thinkable and go with steel. However, the dealers also insisted that the frame should remain similarly damped to the composite designs on which Markaudio has earned a solid reputation inside Japan. By experimenting with metal rapid prototypes, we came up with a pressed form design that required a material thickness of 0.8mm with a tolerance of 0/-0.1mm under stamping conditions. This spec is some 0.2mm to 0.3mm thicker than standard frames of this type. I designed 2 new damper rings, one for the motor to frame sub-assembly, the other for the front suspension to frame fit. This front damper is quite interesting. We found a particular paper type that had the density needed to do the job. This damper ring fits between the frame surface and the front suspension.

Power-train: The brief called for a relatively high SPL on +87dB. I nearly got there, coming in @ +86.6 dB. The brief also called for paper as the Japanese market in this class of driver favours the material. This was a major challenge as our paper mixes are tolerance sensitive which makes it hard to produce them for a low price point. However, we persevered, coming up with an affordable formula which didn't fall down on performance. The dealers also wanted a relatively flat response to appeal to newer and younger Diyers who have less tuning and tweaking skills. So coil and cone matching took some time to get the balance right for this goal. The front and rear suspensions remain our standard design as used on Gen. 2 CHR's. They do their jobs well.

Motor: The magnetic power of the Motor sub-assembly is slightly de-tuned from other 70mm class Markaudio drivers. Due to this driver's power-train moving load < 3.5grams and cone profile, it become necessary to limit the level of flux density in order to maintain a flatter frequency response. While I would like to get this design to +87dB, there's always a compromise to be drawn when designing drivers.

Performance: This response for this driver is reasonably flat. Due to the relative low mass, some variations can be observed in the frequency spectrum. Likely once inside a box, a rolling off from around 8kHz will likely occur. It shouldn't be a pronounced as the current CHP70 model, which incidentally is selling remarkably well. The CHN-70 is intended for budget general diy/home audio applications where longer listening sessions require a "neutral" sound. Those users who wish to boost the CHN-70's upper responses will find it very adaptable, easily driven up by active equalisation. For those users who want more in-built "fizz" at the top end, the CHR70 Gen.3 would be more suited.

Outlook: While this driver was initially intended for Japan, Madisound expressed an interest to introduce it to a wider audience. I'm not sure as yet what price they will set but it will be "affordable" the lowest cost of all our models. For those home and custom makers on a tighter budget looking for a driver that's still custom made (not a parts bin after-though re-named special) the CHN-70 could be an answer. As its specs suggest, its likely to be a well mannered relatively neutral driver, tweaked and tuned with relative ease, at home in a variety of box seizes and designs.

Pic and PDF data sheet attached to this post.

Enjoy
Thanks
Mark.

Last edited by markaudio; 30th July 2014 at 01:17 AM.
 
Old 30th July 2014, 01:12 AM   #2
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Looks like these will be optimum in slightly larger boxes than CHR/CHP

dave
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Old 30th July 2014, 01:20 AM   #3
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Quote:
Originally Posted by planet10 View Post
Looks like these will be optimum in slightly larger boxes than CHR/CHP

dave
Hi Dave,
Yep, more or less around the box sizing I was looking at. The idea of of this driver is to be an easily affordable all-rounder. Fitting somewhere between the CHP which suits those who want a well damped top end and the blighter sound of a CHR. Hoping I'e got it about right.

Thanks
Mark
 
Old 30th July 2014, 01:39 AM   #4
Bigun is offline Bigun  Canada
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ooh, this looks very nice - in fact it's quite a sexy looking driver. And the posted frequency response just happens to be a better fit to my ears as I am not a fan of the Fostex sizzle. And no routing required to recess the driver, lots of wood for the mounting screws to grab onto. Good box size - yup, even though I'm no expert in any shape or form I do like the look of this. I'll be watching for reports from the early adopters

If only it was 90dB (just kidding!)

Edit: those curves do look to be around 90dB (just a matter of where you put F0) !
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Last edited by Bigun; 30th July 2014 at 01:49 AM.
 
Old 30th July 2014, 01:49 AM   #5
chrisb is offline chrisb  Canada
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An interesting glimpse into the delicate balancing act involved in designing to address customer feedback, as opposed to the " take it or leave it"

I think a lot of folks will quite enjoy working with the low profile stamped frames - I certainly have no issue with them- as long as the driver sounds good- which if recent models and upgrades are any indication, these certainly will.

I bet you'll sell tons of these little buggers

Edit: to enclosure designers - on your Mark, get set, go
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Last edited by chrisb; 30th July 2014 at 02:07 AM. Reason: Gramur
 
Old 30th July 2014, 01:52 AM   #6
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Quote:
Originally Posted by Bigun View Post
ooh, this looks very nice - in fact it's quite a sexy looking driver. And the posted frequency response just happens to be a better fit to my ears as I am not a fan of the Fostex sizzle. And no routing required to recess the driver, lots of wood for the mounting screws to grab onto. Good box size - yup, even though I'm no expert in any shape or form I do like the look of this. I'll be watching for reports from the early adopters

If only it was 90dB (just kidding!)
Hi Big,
Thanks. Its interesting in Japan as this time where early adopters are doing quite well with CHN. Understandably, its being compared to the 103En but its viewed a quite a different animal. The thinking is the CHN is better in the low and middle, the Foss for the highs. I'd say this is about right as there's no point me repeating a design like the 103.

The interesting experimenting happens for those with active filtering/equalisation. There I believe the CHN has the edge since it retains the Markaudio long-throw design, much easier to tweak the top end knowing you've got coil length to play with in the lower frequencies. No offence to Foss users, its just my design thinking which is an alternative to more traditional high SPL short stroke designs.

Thx
M
 
Old 30th July 2014, 01:56 AM   #7
syklab is offline syklab  Hong Kong
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Hi Mark,
Will this be available in HK?

Last edited by syklab; 30th July 2014 at 02:21 AM.
 
Old 30th July 2014, 01:59 AM   #8
Bigun is offline Bigun  Canada
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I've not heard them yet of course, but I'm not sure any EQ at the high end will be needed. Maybe tastes are different in Japan but I find the upward tilt and the cone resonances that some other brands suffer from to be tiresome. Sure, they sound detailed and exciting at first, but it wears off. Worse still, it may put people off the whole full range thing if their first experience is unfavourable. So - I'm not going to accept 'the thinking' that the CHN is going to give up anything for the highs

The 4mm xmax is another good item. (boy - it took 5 goes to get this computer to write xmas instead of xmas - see what I mean)
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Old 30th July 2014, 02:08 AM   #9
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Quote:
Originally Posted by chrisb View Post
An interesting glimpse into the delicate balancing act involved in designing to address customer feedback, as opposed to the " take it or leave it"

I think a lot of folks will quite enjoy working with the low profile stamped frames - I certainly have no issue with them- as long as the driver sounds good- which if recent models and upgrades are any indication, these certainly will.

I bet you'll sell a tons of these little buggers
Thanks Chris,
Your correct, this driver is very much a result of end-user feedback in Japan in this instance. Japan Diyers were/are complaining about price hikes from the bigger makers, sales volumes were/are falling in this price sensitive category. Hence the approach to me to help redress the situation, the CHN-70 is the result. As this time a CHN driver retails in Japan for around the US$25 to US$30 range which is considered a good deal there. I've asked Madisound to keep retail pricing keen.

Re the frame, allot of work (Evan doing the testing grind when I'm low on energy) to limit extended resonating.

Cheers
Mark.
 
Old 30th July 2014, 02:14 AM   #10
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Quote:
Originally Posted by Bigun View Post
I've not heard them yet of course, but I'm not sure any EQ at the high end will be needed. Maybe tastes are different in Japan but I find the upward tilt and the cone resonances that some other brands suffer from to be tiresome. Sure, they sound detailed and exciting at first, but it wears off. Worse still, it may put people off the whole full range thing if their first experience is unfavourable. So - I'm not going to accept 'the thinking' that the CHN is going to give up anything for the highs

The 4mm xmax is another good item. (boy - it took 5 goes to get this computer to write xmas instead of xmas - see what I mean)
Yep, I know what you mean. I personally prefer a docile driver but its important I do my best to accommodate all tastes. Now the Alpair 7P is a very different beasty to the CHN, different ballgame entirely. You'll see once I get time to publish its specs; And these drivers are also on the Madisound shipment.

Cheers
Mark.
 

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