Mark Audio CHR-70 Application Thread

[tommy_o]

I have a pair of original CHR-70s that I need to rebuild the enclosures for. I'd most likely stay with a smaller bookshelf design, probably ported (maybe sealed), but am open to alternatives. Mark Audio's site doesn't list any plans at the moment (for any driver, actually). Planet10 lists 2 bookshelves (milliSize and Golden Ratio) and the Pensil70.

Are there any other good designs worth looking into before I start, or are there specific advantages I should consider when choosing?

[sayrum]

the point70 would be an option. the "blocking" circuit is on the next page. supposedly sounds very nice. afaiu it is designed for the ch-70 2edition.

[AlexGER]

Hey Tommy,

it depends on how you want to use your speakers?!

In general: The CHR-70 seems to be good in various enclosures. Needless to say that ventilated enclosures of whatever kind (except some small horns) will provide more low frequency information.

If you want to use them in "near-field-hearing" application, a small closed enclosure will work fine. I'am using them like that on my computer desk. Cabinets are ~5liter / 1.32gallons.

Another example is shown here: http://www.hifi-forum.de/index.php?a...=267&thread=20

It's a 4liter / ~1gallone closed cabinet. Specs for the notch filter and the capacitor, which need to be placed in the "+" lead of the speaker to increase bass-perfomance, are listed in the first post.

Regards, Alex

[chrisb]

Originally Posted by tommy_o

I have a pair of original CHR-70s that I need to rebuild the enclosures for. I'd most likely stay with a smaller bookshelf design, probably ported (maybe sealed), but am open to alternatives. Mark Audio's site doesn't list any plans at the moment (for any driver, actually). Planet10 lists 2 bookshelves (milliSize and Golden Ratio) and the Pensil70.

Are there any other good designs worth looking into before I start, or are there specific advantages I should consider when choosing?

If you're thinking that a small bookshelf sized enclosure would be right for you, the 5 liter "milli" sized mMarS (sealed) works like a charm. It's probably no surprise that I've heard most of the P10 designs, and I generally prefer the imaging of the narrow baffle designs over the Golden Ratio.

http://homepage.mac.com/tlinespeaker...map-231009.pdf

a couple of suggestions;

due to Marks' built-in BS compensation, and if they are actually placed in a bookshelf near a rear wall, baffle step compensation may not be necessary

use decent quality plywood, not MDF (or contact Dave at commercial site re flat pack kits for these in 15mm BB)

[Nanook]

or whatever they call them now...(?prime?). Quite small and great sounding, but all will sound best if on stands....

[chrisb]

Originally Posted by Nanook

or whatever they call them now...(?prime?).

- at one time the thought was to indicate the primacy of the 13 liter enclosure first designed for the CSS FR125, then FE127E, but once other drivers entered the picture with their different volume requirements, the naming convention got very confusing - I still try to think in terms of 3 basic form factors - but you know Dave

Quite small and great sounding, but all will sound best if on stands....

agreed, but sometimes when it's a matter of hang from the wall on brackets, in a bookcase or nothing, I'll take the not nothing.

[planet10]

Originally Posted by Nanook

or whatever they call them now...(?prime?). Quite small and great sounding, but all will sound best if on stands....

CHR-Ken for short (dCHR-Ken70 in full form, d=deci (as in one sze down from the original Fonken) and 70 for the 70mm CHR (i am anticipating other sizes of CHR eventually)). Name coined by a member here, and pronounced as per the sea monster.



dave

[tommy_o]

Originally Posted by planet10

CHR-Ken for short (dCHR-Ken70 in full form, d=deci (as in one sze down from the original Fonken) and 70 for the 70mm CHR (i am anticipating other sizes of CHR eventually)). Name coined by a member here, and pronounced as per the sea monster.



dave

Dave can you describe the dCHR-kens enclosure? I see that loans are for sale on your site, but I don't have terrible confidence in my woodworking skills. This is a fonken, so it has slotted, forward facing vents? And what is pricing like? Thanks!

[planet10]

Originally Posted by tommy_o

Dave can you describe the dCHR-kens enclosure? I see that loans are for sale on your site, but I don't have terrible confidence in my woodworking skills. This is a fonken, so it has slotted, forward facing vents? And what is pricing like? Thanks!

The larger green/ w silver drivers on the upper right are our demos. These are still doing us service so aren't up for sale. There are versions of this cabinet for A7/A7.3/EL70/FF125wk that use the same shell. At some point trapezodal versions will also be availble (working thru the betas at the moment). The CGR versions (Classic Golden Ratio) are posted for free and are easier to build.

We will do a bespoke order, contact me about pricing, these are not on the price list.

dave

[disjunction]

These are my recently completed mark audio CGR-dCHR-Ken variants.
This is only my second DIY. Both have been based on Dave's planet-10 designs (Thanks for the plans Dave).

main differences:
I had to use different thickness of ply, So the design had to be modified to suit my available materials. Also there no divider (as yet) in the vent. The main regret it that i don't have access to a router which meant i could not have the driver flush with the baffle.
There is however a CNC router going in at the workshop where i work in the future which makes me happy for the the next project

I spent more time finishing this time than the last time and i think it has paid off as the look great (the colour is 'Space' by montana). I used a bobbin sander at 45degrees to chamfer the back of the baffle and holey brace holes.

My impressions of the sound so far (1 day burn in) is that they are pretty picky with amps.
when i plugged them in for the first time i was shocked by the lack of mid and lower mid frequencies. the top end needed to be rolled off but the bass extension was pretty nice. I found this when i had the CGR-dCHR-Kens were plugged into a sure electronic TA2024 D-class amp. I had great success with the sure amp when i built my FR125S-4L5-aperiodic boxes. I think the FR125s benefitted from the detailed high end that the sure amp provided, off setting the limit of the drivers top end.

So, not being happy with the sound of my new speaker i decided to attach them to another amp. I hooked them up to a couple of Flying mole dadm100pro mono blocks.
The improvement was dramatic. Though still slightly lean in the lower mids and still a bit forward in the top end, i could live with that. The extra power from the Moles sorted them out. I think a softer sounding amp could help them further

Cheers
Luke.