Author Topic: Coral 3-ways and a Akai  (Read 14452 times)

Offline oNyX

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Coral 3-ways and a Akai
« on: January 09, 2013, 03:22:59 AM »
I received a pair of 3-way Coral speakers today (the kit one), they are used and not in a good condition. The wood needs some sanding and the cloth must be replaced. Inside the speakers seems fine, they have two caps & two resistors mounted on a strip. No crossovers. The kit doesn't look completed because some screws are missing and there are holes in the wood for screws but no holes below it to tighten the screws. There's only one Coral badge left, sealed brand new.

They have 2H-21A tweeters (20W, 8 ohms), 5M-12 mids (40W, 8 ohms) and 10L-24 Subwoofers (50W, 8 ohms). Each speaker seems to have their own frequency response as stated on the speaker magnets themselves.

Tweeter: 3 - 20KHZ
Mids: 0.8 - 14KHz
Subs: 35 - 2000Hz

So here's my first question: Should I get 3-way crossovers for these, at which frequencies should they cross over and where in the Cape Town area can I get them?

Along with the speakers came an 40 year old Akai AA-910 still in it's box. At first it seems pretty brand new and unused. The aluminum still shines bright with no scratches, but after turning it on I realized the tuning knob for the radio is stuck. So stuck that I have to turn it with both hands. It also has a dual volume knob, but the second small knob doesn't work. It's scratchy and intermittent.
http://audio-database.com/AKAI/amp/aa-910-e.html

Second question: What can I do to ease the the movement of the tuning knob so that it works normal again?

Hopefully the dual volume is replaceable.
« Last Edit: January 09, 2013, 03:27:10 AM by oNyX »
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Offline Atjan

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Re: Coral 3-ways and a Akai
« Reply #1 on: January 09, 2013, 08:46:28 AM »
There are off the shelf xo's  available, but they're far from ideal.
Your best bet is to get the original xo. If not, get someone to help you design a new one from scratch based on measurements.
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Offline mahleu

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Re: Coral 3-ways and a Akai
« Reply #2 on: January 09, 2013, 08:50:42 AM »
I've still got some Coral drivers waiting to go into something. Replace the caps in the existing crossover.

Don't force the tuning knob, you'll break the string which is admin to fix. Open it and see where it's sticking.
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Offline dean

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Re: Coral 3-ways and a Akai
« Reply #3 on: January 09, 2013, 08:59:25 AM »
Please stop calling bass drivers subs   :flame: Goofy
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Offline VS

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Re: Coral 3-ways and a Akai
« Reply #4 on: January 09, 2013, 09:35:33 AM »
Get some switch cleaner (Kontakt K60 is good) and clean out the volume pot before trying to replace it - it will most probably solve your problem. Lube the tuning wheel (where its shaft goes through its attachment to the body) (and all other liitle wheels assoc with the tuning mech).

Offline Kent Kassler

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Re: Coral 3-ways and a Akai
« Reply #5 on: January 09, 2013, 09:39:47 AM »
...and when it's running nicely,kill Dean.
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Offline dean

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Re: Coral 3-ways and a Akai
« Reply #6 on: January 09, 2013, 10:29:13 AM »
 :angrywife:
Contact me for denon, monitor audio,klipsch, rotel,boston,velodyne,marantz,oppo,  B&W.any many more quality brands. We install home cinema , dstv and top line security systems.we now also do nad, mission and psb.yamaha,onkyo,integra,Cambridge audio.svs

Offline dean

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Re: Coral 3-ways and a Akai
« Reply #7 on: January 09, 2013, 10:36:20 AM »
Subwoofer ,a limited bandwidth ,low frequency driver,handling frequencies below 60 hz.
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Offline fdlsys

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Re: Coral 3-ways and a Akai
« Reply #8 on: January 09, 2013, 11:04:13 AM »
....they have two caps & two resistors mounted on a strip. No crossovers....
You live and your learn... Well, some of us do. What do you call a crossover if I may ask? How do we recognise one when we see it?

Or, more directly: Will you please finally read up on the passive "crossovers" (consisting of "filters"...) so that you stop with this "no crossover" nonsense? Please?
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Offline Kent Kassler

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Re: Coral 3-ways and a Akai
« Reply #9 on: January 09, 2013, 11:09:28 AM »
Onyx,the caps and resistors are the crossover,not all speakers carry complex networks bud.
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Offline Atjan

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Re: Coral 3-ways and a Akai
« Reply #10 on: January 09, 2013, 11:17:02 AM »
Ja...I missed the bit about the caps and resistors.

Those are indeed the xo. Does it sound crappy? If so, either the caps have drifted out of spec or they were just crappy to start off with.
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Offline oNyX

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Re: Coral 3-ways and a Akai
« Reply #11 on: January 09, 2013, 12:24:27 PM »
Ja...I missed the bit about the caps and resistors.

Those are indeed the xo. Does it sound crappy? If so, either the caps have drifted out of spec or they were just crappy to start off with.

It doesn't sound crappy, it sounds good. I just wanted to know if real 3-way xo will improve the sound.

The caps are 50V 6uF and resistors are 5W 5 Ohms.

As for the amp, the tuning knob has a type of weight inside but the Allen Key  screw is also stuck and is starting to crack around it.
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Offline oNyX

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Re: Coral 3-ways and a Akai
« Reply #12 on: January 09, 2013, 12:26:53 PM »
You live and your learn... Well, some of us do. What do you call a crossover if I may ask? How do we recognise one when we see it?

Or, more directly: Will you please finally read up on the passive "crossovers" (consisting of "filters"...) so that you stop with this "no crossover" nonsense? Please?

Technically it's more of a filter than a crossover. A crossover splits frequencies, caps prevents or limits the lower frequencies from entering the tweeters.
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Offline Atjan

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Re: Coral 3-ways and a Akai
« Reply #13 on: January 09, 2013, 12:37:29 PM »
:popcorn:

If you can get someone to design a proper xo it will almost certainly sound better. The xo you have now is the way it is because of cost considerations.

I'd replace the cap, just to be sure.

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Offline oNyX

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Re: Coral 3-ways and a Akai
« Reply #14 on: January 09, 2013, 12:47:32 PM »
The caps look fine, but isn't it a bit too high? Most have 2.2uF - 4.7uF but these has 6uF.

I guess higher is better, make them sound sharper.
« Last Edit: January 09, 2013, 12:51:05 PM by oNyX »
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