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Hi
I got 3 old (~1980 ?) 4" Coral speakers.
I don't know if they are considered "high eff.", but I was told that you guys might give me some help.
I'm looking for any kind of info on these nice drivers.
I've tried Google, but nothing turns up.
Any links/mail-address to people with Coral-knowledge would be appreciated.
Regards TroelsM
Follow Ups:
[Ive seen 4 different versions of the Coral flat 5. ]
I found out about series I, II, III from the link below, and you know the forth one?
http://fullrangedriver.com/forum/viewtopic.php?id=531
[The paper dustcap drivers i have had and still do own. They are a little sweeter than the aluminium dustcap drivers. Not a huge difference but so easy and cheap to do. You will like the result.]
Will probably give it a try!
[Enclosures. The wrong enclosure will kill these drivers dead. Ive heard them in 3 enclosures that i liked (and quite a few i didn't). ]
Excellent info! Will first look into the ported one, and also see if there are any BLH cabinets available around too.
[The flat 5 II's are the sorts of drivers you have to work with for a while to coax the best sound out of them. When you get them right they are wonderful. I much prefer what im listening too now but you will really love them. ]
Will post the listening results once they are installed and played : )
Thank you so much VirginVinyl and let me know if you have more information on these units!
Regards,
CFT
In Reply to: RE: Coral 4" speaker posted by cft on October 31, 2008 at 23:42:46
Hi VirginVinyl, great, so you are familiar with these units!
[They look like they are the Series II flat 5's. The very last few hundred of these had paper dustcaps which sounded slightly sweeter and more natural. Not a big difference really.]
Have you heard those with paper and Al? I was thinking of replacing the dented aluminum caps with paper ones. You think that's worthwhile? Or simply lift them back up...
BTW, the seller said these units were manufactured for a Danish dealer (biggest, worldwide for Coral)and they have higher efficiency (~94 dB) and better freq range than the flat 5 [II ?], and their closest relatives are the mk III black frame (he might mean series III). Anyway, waiting for his further reply. Do you know of mk III black frame? Would you think they are similar to series II?
[In the right enclosure and in a room that isn't too big so they 'load' the room you will a very beautiful sound.]
Really? terrific!!
[What enclosures are you planning on putting them in?]
Good question, no answer, any suggestion you may have? will appreciate it very much!!
CFT
Hi again,
Ive seen 4 different versions of the Coral flat 5.
The series 1 with a alnico magnet. Sounded very aggressive, due i have been told to the surround which was changed in the series 2.
Unfortunately the series II lost the alnico magnet but gained a surround which better damped the cone resonance. The series one was an ok driver, the 2 a magical one.
The paper dustcap drivers i have had and still do own. They are a little sweeter than the aluminium dustcap drivers. Not a huge difference but so easy and cheap to do. You will like the result.
Enclosures. The wrong enclosure will kill these drivers dead.
Ive heard them in 3 enclosures that i liked (and quite a few i didn't).
No one best and they all sound very different.
Concrete spheres made by Michael Brown outside of Canberra, Australia. He called them the audiospheres and they sound lovely. Quite electrostatic like (clean and clear). They were on short stands placing the spheres quite close to the floor which they needed for proper bass loading (otherwise they were just too lean and clean, robbing music of timber and foundation). Least boxy sounding box solution ive heard them in.
Small front ported wooden enclosure. Chipboard not mdf. Richer and fuller timbers than the audiospheres. A more weighty 'meaty' presentation. Also more corse, boxy and resonant. No clear pure electrostatic sound here but with its own charms.
Rear horn. Around i guess a metre tall. About 7 inches wide and maybe 60 cm deep. This enclosure sounded great but very different to the other two above. Lots of slam. A large sound. Direct, vivid. Maybe too direct and vivid. Suited some music much better than others. Great for Jazz, which is not really my thing. Also worked pretty well on blues and lovely on female vocal. Could be used in a larger room also due to the driver not working very hard. Along with the sphere above, the most ruthless implementation. By that i mean that your electronics and system better be up to scratch and tailored to complement the speakers or you'll hear it.
The flat 5 II's are the sorts of drivers you have to work with for a while to coax the best sound out of them. When you get them right they are wonderful. I much prefer what im listening too now but you will really love them.
See
http://www.audioasylum.com/cgi/t.mpl?f=hug&m=137419
WarmestTimbo in Oz
The Skyptical Mensurer and Audio ScroungerAnd gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
http://www.theanalogdept.com/tim_bailey.htm
The spheres had two fathers - Michael Brown and David Jones, apart from Olson on wave-launch, they did not know that curved surfaces have very low bending modes as well.
Eg, a sphere made of different radius rings of MDF, clamp-glued and then turned smooth, would be a lot lighter than concrete, and faster. And very probably quieter than Celestions 600 and 700 boxes. I've heard both models and despite disappearing they till sounded like boxes.
IME for the Flat 5 the box enclosures threw away just about everything the spheres got right, and got in the way of much of what the Flat5's get right.
Floor loading does help with the baffle diffraction step (BDS), but adds early reflections in front of the enclosure.
The model 2's # (Coral Fl5), and M3 * (the Fostex 2-way), and M4 #(2 x Coral Fl5) all had BDStep issues. *No LP filter/ # no filters. I've always wondered what an M4 would sound-like if the second 5 was only fully effective from their -3db BDS point and on down IE as a 1.5 way design, ;-)!
Near to wall mounting on adjustable articulated arms strikes me as likely to keep most of the sphere 2's launch right, and give some broadband bass boost. I used to run my LTLoan pair in the bedroom on tall stands about 2.5feet out. Articulated? Hard to wall for when you're not listening closely, and out for close attention sessions. But they still can't/don't do bass. More than half the 5's I find are burnt out, by people trying to MAKE them do bass.
IMO the best way to use a pr of 5's in sphere2's is from no lower than 150 and all the way on up. The lower down the steeper the high-pass needs to be. Just like with single pairs of 57's - ;-). As the link, in the post above, sets out.
Did you ever find a fill-in / 'super' tweeter to go with the 5's that was worth the trouble? I've heard the Foster/x RPT in that role (the one with the round mounting plate) but thought it needed a small wooden sphere - ;-) as it was audible and placeable. I'm thinking of that small 16?mm Dayton?!
What is your opinion of pole-piece extensions - misnamed phase-plugs - for a pr of metal dust-cap Flat 5's? IE remove the dust caps and put a turned 'bullet' on the central magnet pole?!
JBTW David J taught me how to set-up sprungies, and I now have their Linn jig!
http://www.theanalogdept.com/susp_tim_bailey.htm
TIA
WarmestTimbo in Oz
The Skyptical Mensurer and Audio ScroungerAnd gladly would he learn and gladly teach - Chaucer. ;-)!
'Still not saluting.'
http://www.theanalogdept.com/tim_bailey.htm
Hello TroelsM
Is it coral 4A71.
If yes i can send you all infos about this speaker.
It is 90 db eff.
Never use but just have a notice with differnet coral drivers.
Regards,
Marc
Hi TroelsM,
I haven't seen a Coral 4 incher like this one before. The basket and finish on the magnet also is not similar to any I have seen.
Can you post photos of the front of the cone?
I have owned various Corals of the flat series and also the Beta 8 and both early and later versions of the Beta 10.
The best sounding Coral speaker ever made was called the flat 5 which your driver may be similar to? If your driver is similar you are very lucky. The flat 5 series 2 was one of the best full range drivers ever made. The only full range driver i heard which i thought was better was the Goodmans Axiom 80 and the Phy and only in some areas. The Flat 5 will give you the best vocal reproduction from a full range driver you have ever heard. Its also lightning quick with its 3 gram moving mass and a super smooth response. These are much better in sound to the Beta 8 and 10 other than in loudness capability and bass response. In the correct enclosure you will get nice response to around 50hz.
Its achilles heal was its power handling (not too great in really large rooms or if you want to play it real loud) and its low end which not surprisingly for a 5 incher will not compete with a Beta 8 or a Beta 10. Balance is similar to a hot rodded quad 57 (grills removed, placed on its side ala dapalito style and well off the floor, third of the way into the room, rear horse hair blanket removed and almost touching the side walls and about 50cm off the floor). You will hear detail and a sense of 'thereness' you have probably not heard before. In saying that in a proper enclosure it will play to a slightly louder level than a 57.
Your drivers may be worth up to about $300 US if they are similar to the flat 5. They are very hard to find. I've never seen any that look like yours before so if they are the real deal and if they sound as good (2 big if's) then they may be worth more.
Most Corals play at a totally different level to the similar looking (and totally different sounding) Fostex drivers. You have to look to drivers like the Goodmans Axiom 80, PHY and Supravox drivers to get similar or better performance if you're after that full range driver sound.
There is a pair on Ebay in Australia at the moment (search number: 130146411768 ). You can look at photos to see if the cone is similar to yours. These ones are the flat 5 series 2 drivers which are better than the earlier flat 5 series 1. The series one had a peak in its response which was totally cured when Coral changed the surround material for the series 2.
One great mod which some people do to the series 2 is to replace the aluminium dustcap with one made from paper (as has been done to the one in the ebay link mentioned). It makes the top end slightly sweeter and is what Coral did to the final batch of 500 or so Flat 5's before the company closed down (or was taken over). If your cone has a aluminum dustcap you may wish to try this tweak yourself.
The drivers, like the Axiom 80's are very revealing of your equipment. If you have any problem with your electronics, the speakers will show it up. Get it right and you are there.
Please post photos of the front of the cone if possible to try and discover more.
Hope this helps.
Re "One great mod which some people do to the series 2 is to replace the aluminium dustcap with one made from paper (as has been done to the one in the ebay link mentioned). It makes the top end slightly sweeter and is what Coral did to the final batch of 500 or so Flat 5's before the company closed down (or was taken over). If your cone has a aluminum dustcap you may wish to try this tweak yourself."
From 1975 to 1985 I was involved in the production of Audiosphere concrete sphere enclosure loudspeakers using the Coral Flat5-II driver (Sphere2). The original prototypes were built around 1976-77, using the earlier version of the Flat5, which was unlistenable due to severe cone resonance problems. Coral resolved this problem with the Flat5-II, with improved treatment of the cone surround. We were still aware of some 'shout' being caused by the duralium dust cap, and around 1979-1980 placed a special order for 300 modified Flat5-II's fitted with the paper dust cap from the Coral 4A-60. Most Audiosphere Sphere2's are fitted with this driver.
I agree with the comments in the post about the Flat5-II - despite its modest specifications, it remains one of the best fullrange drivers ever made. It required an enclosure like the Sphere2 to achieve its full potential, and could sound very thin and nasty in conventional boxes. It was ideally suited for use with low-powered triode valve amps and solid-state Class A amps (eg Sugden A21). Its rendition of pianos and voices is still unsurpassed by most commercial loudspeakers.
Several Sphere2's were purchased by people who had previously owned Quad's - the Sphere2's achieved the transient performance of the Quad's without the dynamic range limitations typical of electrostatic loudspeakers.
Hi mstr_bojangles,
Just ordered a pair of Coral Flat 5, could you tell me whether they are of series I, II, or III?
Thanks!
Hi CFT,
Congrats on picking up these beautiful little drivers. Its unfortunate that there is not more discussion on really wonderful fullrange drivers like these.
They look like they are the Series II flat 5's. The very last few hundred of these had paper dustcaps which sounded slightly sweeter and more natural. Not a big difference really.
In the right enclosure and in a room that isn't too big so they 'load' the room you will a very beautiful sound.
What enclosures are you planning on putting them in?
Dear mstr_bojangles ;
I came across your discussion on Coral drivers and was very interested in your experience. Is it possible that I can contact you directly via email to discuss this further? [what is your email address?]
Thank-you
Regards;
BN
Hi.
Thanks for the fast answer.
My drivers doesn't look like the ones from ebay. The ones from ebay look like the "normal" vintage corals. I'm not sure that mine are fulrangers.
Mine has a very solid frame and a somewhat small magnet. Build qality are high.
The centerdome are inverted. Diaphragm and Dome are paper. Look very, very light. It has decent Xmax (linear or not?) and soft suspension. VC looks to be approx 1".
I'll post more pictures in the next days.
I'll try to measure T/S some day, but I haven't got the equipment right now. I'm thinking of speaker workshop?
Regards TroelsM
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