Active Speakers

Cooper005 · 30th January 2012, 07:22 PM

Hello,

As I'm new I'll say hi to everyone, I'm Jasper.

I am planning on building my own speakers from scratch for a school project but they are still for my own use later. At the moment we have a stereo with the speakers connected (the normal). Now, I would like to make two speakers with a build in amplifier, so that it is possible to play music from my iPod by directly connecting it to the speakers. I don't know much on how to do this and hope somebody can answer my questions. I have found 2 Coral Beta 6 drivers which I will use.

Do I need a 2 way system to get a reasonable sound? as the beta's won't be full enough.

Which amplifier do I need to use? Is it possible to use 2 mono amps?

Will the Corals preform well in an enclosed cabinet?

Thanks,

gfiandy · 30th January 2012, 07:55 PM

How much time do you have for this project. I would recommend matching the build to your time resource.

As things normally take much longer than you expect I would simplify the project as far as possible. If you want to improve it later then you will have a starting point and some experience to work from.

My approach to this as a school project would be to use the one driver as it is full range. Buy two. Mono amplifier kits which take a low voltage input. No more than 24v. Find two cheap built power supplies of about 20 to 30 watts at 12 -24v.

Now what you need to do is research the right size enclosure for you speaker and work out if a port will work or not. There are several free programs to help you with this.

Build the enclosure, fit the amplifiers and sockets for the power input and audio connection for your iPod.

This is plenty of work for a school project. Depending on what subject it is for if it is design tec I would drop the power amps to start with and just do the enclosure and wire it up as a passive speaker to start with. Then if you have time left go onto the power amplifiers if you have time.

Regards,
Andrew

Cooper005 · 30th January 2012, 10:05 PM

Thanks for the quick response. I don't have that much time, max. 2 months but I have other work as well. I have to say though that this is more my own project but I will use it for school, it is important they work well. I chose the enclosed cabinet as I thought this would be the easiest. I'm waiting for the drivers, when I get them I will connect them to our stereo to hear them and decide from there but I would prefer to just use those as you said. I'll have a look for a programme to calculate the enclosure.

How can I connect the iPod to the amps and get a stereo sound?

Thanks again,

chrisb · 31st January 2012, 05:36 AM

Quote:

Originally Posted by Cooper005

How can I connect the iPod to the amps and get a stereo sound?

Thanks again,

this has gotta be the easiest part of your project - there are any number of simple iPod docks or even just mini headphone to RCA patch cords that can do that for you

for about $100 the Pure i20 dock is a stupidly good sounding direct digital dock - it bypasses the iPod / iPhon's built in DAC and replaces with its own fairly decent one, and as well has coaxial and SPDIF outputs for connection to an outboard DAC

talaerts · 31st January 2012, 06:40 AM

Quote:

I'll have a look for a programme to calculate the enclosure

WinISD is free and easy to use.
But you'll need to find the Thiele Small parameters for those Corals for a good simulation. Google may help.
Foresee enough space above the coral in the front baffle so that you can possibly later add a tweeter, should this be necessary.
For an affordable yet ok amp, google for Gainclone kit. Several are available.

Cooper005 · 31st January 2012, 07:27 AM

The Beta 6 is I think a bit in-between. If I would want it to be a more powerful speaker should I add a tweeter or a low range speaker?

Thanks for the Gainclone suggestion. WinISD is for windows only.

The iPod dock is not really necessary for me. As long as it's properly connected it can just lay on top.

talaerts · 08:46 AM

It is a full range unit, it may be ok as is, certainly according to the specs.

Yes, it is a pain that winisd does not run on a mac, but surely someone you know has a pc you could use?

fyi here you can find the official coral plans for closed (rather big) and vented enclosure:

Perhaps simply make these?

You could also envision an old-fashioned kind of all in one music system, with the two speakers in one bigger box (keep the volumes of enclosure and vents), with a cutout on the top for an ipod dock (these come with a remote!)

Cooper005 · 31st January 2012, 09:01 AM

Thank you that's really helpfull, I didn't find the official numbers for a beta 6 closed cabinet. If I was to add a tweeter, would the enclosure change a lot?

About the all in one speaker. This would be a lot easier but I am afraid the sound will not be as good.

talaerts · 31st January 2012, 02:34 PM

Well the closed cabinet dimensions are in the right column.
There is plenty of space below the main speaker in case you want to add a tweeter.
For an all in one design (inside it must still be two boxes!), think about it as a cool ipod speaker which are usually small, not as a pair of speakers. The stereo effect will be less but it could be cool.

Cooper005 · 31st January 2012, 05:32 PM

I have decided to make 2 separate speakers, we have the space for it. As long as it's easy. I am looking for a mono block that has the power supply already build in. I want to keep it simple so chances of messing it up are minimum. I found these secondhand mono blocks with the following specs but I have no clue if they are suitable for the coral beta 6 + tweeter (per block)

Rated Power, rms 20-20.000 Hz @ 0.03& THD
125 watts/8 0hms
Frequency response (+0, -0.4 dB) 10Hz-20Hz
THD 0.03%
IMD 0.03%
SN -100 dB (A weighted)
Voltage gain 29.2dB
Input Impedance 24K ohms
Damping factor >500

It might be too powerful? Then I was wondering how you get a stereo sound. The device has a single rca input and a xlr input.

31st January 2012, 08:43 AM	#7
talaerts diyAudio Member Join Date: Oct 2005	It is a full range unit, it may be ok as is, certainly according to the specs. Yes, it is a pain that winisd does not run on a mac, but surely someone you know has a pc you could use? fyi here you can find the official coral plans for closed (rather big) and vented enclosure: Perhaps simply make these? You could also envision an old-fashioned kind of all in one music system, with the two speakers in one bigger box (keep the volumes of enclosure and vents), with a cutout on the top for an ipod dock (these come with a remote!) Last edited by talaerts; 31st January 2012 at 08:46 AM.

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30th January 2012, 07:55 PM	#2
gfiandy Audio Engineer diyAudio Member Join Date: Jul 2003 Location: Cambridge UK	How much time do you have for this project. I would recommend matching the build to your time resource. As things normally take much longer than you expect I would simplify the project as far as possible. If you want to improve it later then you will have a starting point and some experience to work from. My approach to this as a school project would be to use the one driver as it is full range. Buy two. Mono amplifier kits which take a low voltage input. No more than 24v. Find two cheap built power supplies of about 20 to 30 watts at 12 -24v. Now what you need to do is research the right size enclosure for you speaker and work out if a port will work or not. There are several free programs to help you with this. Build the enclosure, fit the amplifiers and sockets for the power input and audio connection for your iPod. This is plenty of work for a school project. Depending on what subject it is for if it is design tec I would drop the power amps to start with and just do the enclosure and wire it up as a passive speaker to start with. Then if you have time left go onto the power amplifiers if you have time. Regards, Andrew

30th January 2012, 10:05 PM	#3
Cooper005 diyAudio Member Join Date: Jan 2012 Location: Netherlands	Thanks for the quick response. I don't have that much time, max. 2 months but I have other work as well. I have to say though that this is more my own project but I will use it for school, it is important they work well. I chose the enclosed cabinet as I thought this would be the easiest. I'm waiting for the drivers, when I get them I will connect them to our stereo to hear them and decide from there but I would prefer to just use those as you said. I'll have a look for a programme to calculate the enclosure. How can I connect the iPod to the amps and get a stereo sound? Thanks again,

31st January 2012, 07:27 AM	#6
Cooper005 diyAudio Member Join Date: Jan 2012 Location: Netherlands	The Beta 6 is I think a bit in-between. If I would want it to be a more powerful speaker should I add a tweeter or a low range speaker? Thanks for the Gainclone suggestion. WinISD is for windows only. The iPod dock is not really necessary for me. As long as it's properly connected it can just lay on top.

31st January 2012, 09:01 AM	#8
Cooper005 diyAudio Member Join Date: Jan 2012 Location: Netherlands	Thank you that's really helpfull, I didn't find the official numbers for a beta 6 closed cabinet. If I was to add a tweeter, would the enclosure change a lot? About the all in one speaker. This would be a lot easier but I am afraid the sound will not be as good.

31st January 2012, 02:34 PM	#9
talaerts diyAudio Member Join Date: Oct 2005	Well the closed cabinet dimensions are in the right column. There is plenty of space below the main speaker in case you want to add a tweeter. For an all in one design (inside it must still be two boxes!), think about it as a cool ipod speaker which are usually small, not as a pair of speakers. The stereo effect will be less but it could be cool.

31st January 2012, 05:32 PM	#10
Cooper005 diyAudio Member Join Date: Jan 2012 Location: Netherlands	I have decided to make 2 separate speakers, we have the space for it. As long as it's easy. I am looking for a mono block that has the power supply already build in. I want to keep it simple so chances of messing it up are minimum. I found these secondhand mono blocks with the following specs but I have no clue if they are suitable for the coral beta 6 + tweeter (per block) Rated Power, rms 20-20.000 Hz @ 0.03& THD 125 watts/8 0hms Frequency response (+0, -0.4 dB) 10Hz-20Hz THD 0.03% IMD 0.03% SN -100 dB (A weighted) Voltage gain 29.2dB Input Impedance 24K ohms Damping factor >500 It might be too powerful? Then I was wondering how you get a stereo sound. The device has a single rca input and a xlr input.