Mark Audio CHR-70 Application Thread

[Elias]

Since I have a couple pairs of these laying around awaiting a glorious home I figured I'd start a thread for others to post their ideas and design applications into.

Hi,

CHR-70 application:

An externally hosted image should be here but it was not working when we last tested it.

It's single stereo speaker with 3 elements. Stereo sound using passive matrix circuit. Steerable directivity pattern. Utilises room as a sound projector.

Elias Pekonen Home Page - Stereophonic Sound from a Single Speaker


- Elias

 

[mashaffer]

What clever grills.

 

[fakeout]

Hi,

CHR-70 application:

An externally hosted image should be here but it was not working when we last tested it.

It's single stereo speaker with 3 elements. Stereo sound using passive matrix circuit. Steerable directivity pattern. Utilises room as a sound projector.

Elias Pekonen Home Page - Stereophonic Sound from a Single Speaker


- Elias

Are those 80mm, 92mm or 120mm (computer fan) grilles?

 

[planet10]

Given that they are covering CHR, they'd need to be at least 120mm.

dave

 

[Elias]

Yes those are chromed steel fan grills.

There are more behind the concept than the grills


- Elias

 

[sk971]

Hi Guys
New on here, and sorry to dig up an old thread but I have a question about these drivers.

I am looking to build some floorstanders with a very small footprint and was originally looking at the Zigmahornet, though there seems to be some issues with this design.
So now I am considering the Pensil70 I wonder if you could advise me wether this is compatible with the new gen3 CHR 70s or EL70.
Also my amp is an old Arcam Delta 290 rated at 75w would this be execessive?

Thanks in advance Simon

 

[chrisb]

Hi Guys
New on here, and sorry to dig up an old thread but I have a question about these drivers.

I am looking to build some floorstanders with a very small footprint and was originally looking at the Zigmahornet, though there seems to be some issues with this design.
So now I am considering the Pensil70 I wonder if you could advise me wether this is compatible with the new gen3 CHR 70s or EL70.
Also my amp is an old Arcam Delta 290 rated at 75w would this be execessive?

Thanks in advance Simon

Pensil is a great sounding box (so far I've built for A7.2 and A12.2P), drawing for the CHR70.3 is to be found here:

http://frugal-phile.com/boxlib/pensils/Pensil-R70s3-map.pdf

Be sure to assemble with removable back to allow for adjustment to damping fill levels - this is a very narrow profile box with a small driver cutout - a very tight fit, and even the smaller drivers benefit from at least minimal bracing .

I've also built a cute little vented mono-pole floorstander for the EL70 - the drawings for which are (to be) included in a complete subscription planset from here:
planet_10 hifi

(if Dave was fully awake as of the hour of this posting, he'd apologize for the current state of confusion of the websites - he's having to conduct a "Dr Frankenstein" reconstruction- attempting to reanimate from an assemblage of broken and mismatched parts) .

Note that the EL70 are nominal 4ohm, but unless your Arcam has conniption fits with this load it should be fine.

Also note that a lot of these "small footprint" floorstanders can be rather tippy, and all benefit from either ballasted / extended base plates.

 

[sk971]

Hey Chris

Thanks for you reply.
I was actually looking at the original Pensil70 which is taller and leaner.There doesn't seem to be much info on this design(not a good sign perhaps ?)

I live in london in what can be best descibed as a cosy sized flat and anything with a shallow footprint would be a major advantage.

I can see now that stabilty is a problem so will definately weight them down.

Cheers Simon

 

[chrisb]

Hey Chris

Thanks for you reply.
I was actually looking at the original Pensil70 which is taller and leaner.There doesn't seem to be much info on this design(not a good sign perhaps ?)

I live in london in what can be best descibed as a cosy sized flat and anything with a shallow footprint would be a major advantage.

I can see now that stabilty is a problem so will definately weight them down.

Cheers Simon

Simon, the revision to the CHR70's T/S parameters probably explains the dearth of builds / online "reviews" of all enclosures for same - few of us have resources to build (or store) versions of every design for each new version of a model family
-although Sue and Ruth to name at least 2 would attest to our attempts to that goal - each new build Sue sees (which is not all of them ) elicits the same question and rolling of eyes at the reply

"Those are cute/pretty/ etc. - who are they for?"

"Thanks, well , nobody at the moment"

eyes roll here

 

[planet10]

The original Pensil was designed by Mark as a BR, the newer Pensils by Scott, and he took into account the quarter-wave action. The original Pensil should be considered obselete.

All 3 of the CHR are close enuff that all but the smallest boxes wotk fine.

dave

 

[zman01]

sk971,

If you get the new drivers, then the new box will be better.

A very compact shallow design for the CHR-70 is the "Half Towers" - roughly 7.5" x 30" x 5.5" IIRC. Pretty nice for their size.

Noticed BPA has the previous gen Alp 7 on sale:

Markaudio Alpair 7 Gray - Lautsprecherbau von blue planet acoustic

This is probably the save rev driver as ChrisB's. Sorry, couldn't help suggesting, though this is a CHR application thread.

 

[sk971]

Thanks for your thoughts gentlemen, a rethink is in order, most likely going to have a go with the old model Alpair 7s which are just in budget, with the Pensil 7 enclosures and hope that my kit can do them justice.
Cheers Simon

 

[planet10]

Alpair 7 is no hardship

dave

 

[zman01]

Alpair 7 is no hardship

dave

Simon, look forward to hearing from you when you start your build.

 

[chrisb]

Alpair 7 is no hardship

dave

Pensils with 7.2 have been my "daily driver" for probably a year now - as Dave says, no hardship

 

[OOD34]

Folded halfTower ML-TL: 3 dB extra at 32-64 Hz

Hi all,

During Christmas, I made the Folded half Tower ML-TL (free design of planet10) for the CHR-70. I really like the sound.
As from drawing, see below (I made it unintended 3 cm less deep)

I was just curious, what would happen, if I added some extra deflectors inside. To my surprise, the bass get better, deeper and more solid. How it works, I do not know. Just to share.


Regards,

Olaf

PS. is my first project, so I am still on the learning, any feedback, remarks is welcome

 

[KyleinCowichan]

Well done! Perhaps Dave can comment on how those deflectors have had that effect. They definitely cut into the volume of the enclosure.

Kyle

 

[SirByrd]

An externally hosted image should be here but it was not working when we last tested it.

Built these prototypes, ~14 liters, tuned to ~47Hz with a 1"x1" port, F3 of 40 Hz.
Final versions will be out of bamboo plywood.

 

[fastbike1]

Would seem that the increased stuffing likely had the most effect, woudln't you say?

Well done! Perhaps Dave can comment on how those deflectors have had that effect. They definitely cut into the volume of the enclosure.

Kyle

 

[MosMike]

Hello! I have ordered a pair of CHR-70.3 and I plan to use them as computer desktop speakers. As I see the majority of desktop speakers are deep and narrow boxes. But I need a wide shallow cabinet. I found this plan for a 12L BR cabinet: www.markaudio.com/Plans/item/download/60_20ae98d8b2b2e15c02ec6057d7439d2a How will it sound be compared to a traditional deep&narrow cabinet? Is it possible to improve the bass response by making it a 14L cabinet?