Mark Audio CHR-70 Application Thread

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I only paid $46 for this sheet of Baltic birch and if I went A grade no inclusions it was closer to $70 per five by five sheet. If you were to use MDF for the braces you could almost but not quite fit two pair of DMar-kens per sheet.

I have a nice selection of veneers here but they are all raw with no backing so until I find a way to back them with paper I won't use them, the grain makes chip out too prevalent. Any suggestions from the pro's? I was thinking thin drawing paper on a roll like you get from IKEA for the kids easel drawing stands, sort of recycled paperish but fairly sturdy and thin. Any way I've got to find an easier way, this Black Walnut and Bubinga are just staring at me....
 
What is a dMar-Ken70 and are there any plans available? I see lots of talk about these but haven't found any design resources.

I think this is the one you're looking for

http://homepage.mac.com/tlinespeakers/FAL/downloads/Mar-Kel70-1v01f-map-110410.pdf


With some minor modifications to port spacer dividers and driver brace, this design will also fit Alpair 7

Note if flush mounting the version of Alpair7 with extra thick bezel ring, the front baffle will need some adjustment as well - at almost 9mm thick, that doesn't leave a lot of meat for screws on a 15mm baffle.
 
stop building dMar-KeNs now!

once you get the enclosures done, don't put the drivers in them!.

Take the time to finish them, cause if you don't finish the enclosures before you put drivers and dampening material in, you will never (likely) finish them,

WAF is low for unfinished loudspeakers.
 
These seem like good value fullrangers! What do you think about thier application as desktop mini monitors? Should be accurate and detailed?

Not sure how much space I'd have though; Henkjans design is interesting:

http://www.diyaudio.com/forums/full...-chr-70-application-thread-4.html#post1805742

But I'm sure it must be quite bass light? I remember using a Monacor SPH-30X in a ported box though (-6dB @ 72Hz, same as CHR-70 in sealed but with faster ported rolloff) and it giving a suprisingly full sound, so perhaps not? The hump in the response from using the CHR-70 in a smaller box is very minimal, is the capacitor really needed? I can't model its exact effect in WinISD. Nice to use a single polarity amplifier design with though!


It seems it could also squeeze into a fairly small ported box (7.7L) with a lower tuning point to give something of an EBS alignment (attached). The small hump from 100-200Hz shouldn't be an issue as the driver response around here is weaker compared to the 200-500Hz region. Still quite a large box though.

I think with a fullrange driver in particular it'd be desireable to use non-parallel walls, mabye curved sides and/or diffuson patterns on the inside?

A rectangular baffle can give a reasonably flat response with the driver carefully located (attached). The lift at 1KHz is broader than one would like (a high Q lift here would help balance the response nicely), but shouldn't upset it overall.

Any thoughts? Just throwing some ideas out while I consider these drivers!
 

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http://homepage.mac.com/tlinespeakers/FAL/downloads/Mar-Kel70-1v01f-map-110410.pdf
Will this also work the CHR-70? I noticed that earlier quoted dimensions for an dMar-Ken70 were somewhat (tho not significantly) smaller in volume; don't know about slots. Thanks, all!
JF

I think this is the one you're looking for

http://homepage.mac.com/tlinespeakers/FAL/downloads/Mar-Kel70-1v01f-map-110410.pdf


With some minor modifications to port spacer dividers and driver brace, this design will also fit Alpair 7

Note if flush mounting the version of Alpair7 with extra thick bezel ring, the front baffle will need some adjustment as well - at almost 9mm thick, that doesn't leave a lot of meat for screws on a 15mm baffle.
 
http://homepage.mac.com/tlinespeakers/FAL/downloads/Mar-Kel70-1v01f-map-110410.pdf
Will this also work the CHR-70? I noticed that earlier quoted dimensions for an dMar-Ken70 were somewhat (tho not significantly) smaller in volume; don't know about slots. Thanks, all!
JF


The version for the CHR70 and Alpair 7 share different overall dimensions from the EL70 design in above link. In addition, their port slot dimensions vary.

As I get most of my drawings directly from Dave, I'm not always certain as to their location on the site, or for that matter if they're yet posted. (some prototypes are less successful than others)
 
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frugal-phile™
Joined 2001
Paid Member
What is a dMar-Ken70 and are there any plans available?

A very complete set of plans will be available for a small cost once the beta testors have all reported back.

We have been planning on selling comprehensive plans (similar to what Bob Brines does), these are 1st because it is part of a commercial licencing agreement with a manufacturer in Denmark that is building the Alpair7 version as part of his commercial line.

The boxes for CHR70 and A7 are the same except for the details required of the different dimension drivers and slightly different porting. The plans will include both.

dave
 
frugal-phile™
Joined 2001
Paid Member
Mar-Kel70-1v01f... Will this also work the CHR-70?

No. Mar-Kel is for the EL70, Mar-Ken is for the metal cone drivers. With no prefix, the Mar-Kel is the "same" size as the FonkenPrime (PrimeSize). There is also a mMar-Kel which is millSize. the "d" in dMar-Ken stands for deci and is one size down (deciSized)... for more detail on where & what the names of all the miniOnkens mean...http://www.diyaudio.com/forums/planet-10-hifi/160747-minionken-nomenclature-what-those-names.html

dave
 
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