What to do with Hemp CO8Vs?

[Scottmoose]

FYI, these are most likely fancy framed Radian 508s sans the big VC 'dust cover'. Notice the motor design and the fact that Hemp's plots appear to be a copy of the 508's, so Scott, how do these fare in your design?: http://www.radianaudio.com/products/ceiling/8_ceiling.php?viewT=ceiling&viewC=8_ceiling&viewI=

GM

Ha! Figures. Good spot Greg.

Not so great. I prefer this one: 40in x 10.5in x 5in (int HxWxD) Zdriver 8in, Zvent 36in, 4.5in diameter x 1.5in long, same damping. A little like the alignment you used in your FR8c MLTLs. Doesn't go as low as the other, but decent gain & a wide-ish baffle to help counter step loss. Probably have a nice kick in the midbass.

 

[spacies]

Considering the street price of 508s, this begs the question of how good was too good? I mean IMO you'd have to at least match the average 508 price to justify it unless of course there's more to this 'custom' driver than the cast frame and lack of DC the available info implies. For sure, $475 seems a bit much for an 8" co-ax when there's good 12"ers in this price bracket last time I checked: http://estore.websitepros.com/1736754/Categories.bok?category=HEMP+ACOUSTICS

GM

I probably wouldn't have touched if the price was any higher due to the lack of info on these drivers. I paid $400NZD
(400 New Zealand Dollar @ 0.6594 = 263.76 United States Dollar) so yeah, the price was too good to turn down.

I gots a pair of those here for playing with.... anyone know what people are using for XOs?

dave

Hi Dave,

Have you seen these pics?

Boy oh boy do those Radians look similar to the Hemps huh? In fact its very tempting just to buy those crossovers and try them. The part number is Radian 322/08B-2 and you can buy them from here

Another very interesting picture I found online was this one:

That was taken at a HiFi show a couple of years ago. Hemp, Clarity Caps and another company (not Radian) were in the same room. Look closely at that crossover because it is identical to the Radian. Strange how it is in that room when Radian is nowhere to be seen and the fact that these drivers are so similar to Radians 508s.n Maybe this is the crossover for me to try?

Thanks for the box design and graphs guys. I will investigate the Chang cabinets.

Oh, some more pics as promised:

Hopefully I can delete the pics above once I have a few more posts?

Enjoy!

 

[GM]

I paid $400NZD (400 New Zealand Dollar @ 0.6594 = 263.76 United States Dollar) so yeah, the price was too good to turn down.

Strange how it is in that room when Radian is nowhere to be seen and the fact that these drivers are so similar to Radians 508s.n Maybe this is the crossover for me to try?

Hopefully I can delete the pics above once I have a few more posts?

If for the pair, then yeah, you made out like a bandit.

Well, Radian is a prosound company, so wouldn't waste the time/$$$ showing their wares at a HIFI trade show.

Personally, I'd use an adjustable active XO, but if going passive, then lacking any real info on how these may be different from the 508, the factory XO seems as good a baseline as any to start tweaking as I use to do if you can't find one specifically for the CO8V.

Why delete the pics? Others may want/need this info in the future.

GM

 

[spacies]

A bandit, ha ha ha, I like it!

I have tried every supplier of these drivers but none of them have any info. Well all but one, onecaudio. They said they use the Radian crossovers which is why I looked for them
The rest said to try Hemp. I had a good email from Stew and he was going to ask Perry to do numbers. I really hope this comes through, not just for myself, but others too. C'mon boys, help a DIYer out. We are your bread and butter, lol.

As for the pics, sorry, I meant the ones up further I took in the dark. No probs anyway, I will just leave them.

I like the Curvy Chang cabinets. So thats just where these might end up

 

[Scottmoose]

They'll need some changes, assuming the Radian parameters are the more accurate -reduce the vent length to 18mm & depth of each to 15mm. Won't go as low as the intended drivers but you'll get more useful gain. Should be useable good to ~mid 40Hz regions.

 

[seanzozo]

OK, thanks, but where are they on their website? Googling turned up nothing either. Obviously, I don't have a clue about its diaphragm design, but this doesn't jive with the pics and published plots, so pardon me for being skeptical WRT the spec differences, though arguably its material could have an audibly different tone than the 508's.

If it does, it would be interesting to A/B/C them to see if they're even remotely worth the pricing differences between them.

GM

It is not on the Radian website anymore but still available at usspeaker:
http://www.usspeaker.com/radian index1.htm#Dual Concentric Coaxial Speakers

BHTX in a previous post said that the 508 and 5208 had identical t/s -> the CO8 should be no different

 

[GM]

Thanks! Bad link, but had no trouble finding it once I knew Radian's model number. A quick search yielded some good info of it being tonally similar to Tannoy with good reviews from disparate folks, so seems quite the bargain at USS pricing. Looks like a great choice for a high SQ HT system.

Maybe buying the Galante Audio Rhapody's XO plans for a DIY project is a better choice than the stock units, though it may limit baffle width to 18" if it has designed in BSC:

http://www.audiocircle.com/circles/index.php?topic=56501.0
http://www.hawthorneaudio.com/forums/viewtopic.php?f=7&t=2205

GM

 

[spacies]

They'll need some changes, assuming the Radian parameters are the more accurate -reduce the vent length to 18mm & depth of each to 15mm. Won't go as low as the intended drivers but you'll get more useful gain. Should be useable good to ~mid 40Hz regions.

Thanks Scott.
Tell me, if you had a pair what would you put them in too?
Building cabinets is no problem, but I hardly know anything about the measurements and designs, thats why I joined looking for help. I guess I am not a true DIYer but I am learning

BTW you must be the Scott who designed those cabs in the Frugal Horn Site? Great stuff.

Am I wasting my time with these because there are no (supposedly) correct measurements available or should I assume that they are the same as the Radians?

Should I find someone who can take measure them first?

Thanks.

 

[pjanda1]

I think the HA coax specs will be more accurate, as they too were probably done by Radian. I can't vouch for Radians numbers, but surely their measurement of that driver will be closer to reality than their measurement of a driver with a different cone and suspension (their standard coax). Basically, if the specs for the Hemp Coax are wrong, I think you can assume that the specs for the Radian coax are even more wrong for the hemp driver. I'd stick with the published specs and hope for the best. Those Radian guys seem pretty savvy.

pj

 

[GM]

Am I wasting my time with these......?

Should I find someone who can take measure them first?

Hardly!

Ideally you always want to design based on your driver's measured specs and if you don't, then when there's conflicting specs (measured or otherwise) for whatever reason, building to the largest practical design is always what I did and adapted it to suit since it's a lot easier to shrink a cab design internally than expanding it externally, so building Scott's first design and adjusting it to suit if required seems the prudent thing to do if you don't get them measured.

GM

 

[spacies]

Thanks.

So assuming I have no luck from HA, I guess the next best thing would be to get them measured and then its done and I can move on. I will see if I can find anyone here with the equipment but if I have no luck I am happy to send them to a member here.

GM, so you mean this one?
48in x 12.5in x 5.25in (internal HxWxD). Zdriver 17in, Zvent 44in, Vent 3in diameter x 2in long. Line top, back & one side-wall with 1in acoustic fiberglass or stuff 0.45lbs ft^3 from the top 30in down.

Scott, initially you had a MLTL cabinet drawing attached as well. Could you please post it back up so I can copy it?

Many thanks.

 

[GM]

You're welcome!

Right.

GM

 

[spacies]

Small update here.

I have a crossover design and another on the way soon.
Here is my Photoshop representation:

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

I will let you guys know when the next turns up.

Also I have done a couple of drawings for potential cabinets. I have someone doing some number crunching on some Horn software based on this Horn design:

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

Look forward to seeing some graphs on that design.

Also a tall Bass Reflex version of the Magico Mini.

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

I will wait till I see the graphs before deciding on which way to go.

 

[Scottmoose]

Beware 'tall' and 'bass reflex.' Unless you're careful with the dimensions, you could end up inadvertantly creating an MLTL, with an LF response rather different to that you were expecting.

 

[spacies]

Ok,

I could lift the port up higher and just make the bottom 1/3 solid. That would be ok?

Because the Hemp doesn't have a very LF, would a MLTL be suitable? I feel I need to make use of what little LF it does have, hence the ported cabinet. I don't want a sub.

 

[Scottmoose]

See my post 14 in this thread & followups.

What do you think?

 

[spacies]

Scott,

My apologies.
I am very new at this. I just had a look at MLTL cabinets and I realize now what I am looking at. I thought because of the 'TL' they would have a series of dividers inside. My mistake.

Sorry.

If go with the rounded cabinet above, I could still make it square internally. Do MLTL cabinets have any bracing inside?

 

[Scottmoose]

They can do, if desired. Usually a good idea TBH.

Providing the cross-section of the line remains unchanged, the shape of it won't matter (so you can curve it if you wish, that's not a problem).

As it happens, that's one of the several reasons that I'm not a huge fan of the MLTL moniker, as it can confuse people who aren't too familiar with the background.

 

[Davec113]

Presumably HA had hemp cones made for a 5208c.

Sean

Not likely. Tonetubby owns the patent and isn't sharing. This apparently does not stop HA from lying about it...

Exceptional 8 1/2-inch full-range driver uses a 100-percent natural hemp cone, with a 20-ounce ferrite magnet and die-cast aluminum frame.

from:

http://www.audio-magus.com/product_p/wl8.htm

edit: audiomagus is fully aware of this, and allows the misinformation to persist on their website. If it is not misinformation, it is patent infringement. Either way... not honest.

 

[planet10]

Tonetubby owns the patent and isn't sharing. This apparently does not stop HA from lying about it...

Do you have a patent number? (their web site says nothing of a patent -- maybe you mean trade secret?) They might be able to patent a specific recipe for hemp paper w, but that would leave literaly thousands & thousands of other potential recipes out there.

And they would be hard pressed to patent the idea of hemp paper cones as hemp was a very common papaer material before Dow lobbied to have hemp made illegal -- and certainly it would have found its way into speaker cones.

dave

PS: this line really gets me "Even more natural tone than paper". Paper was 1st made with hemp. Their drivers have paper cones...