I have recently purchased a 2 Channel Stereo Amp, which outputs 120W RMS per channel. I have decided to build myself a pair of 2 way speakers. I havent decided on any brands yet because there are a few things I am confused about.
As the Amp is 120W per channel, does this mean that the Woofer and Tweeter have to have a combined wattage of 120W(60 W ea) or does each one have to be 120W?. I will be using a 2 way crossover. And another thing, what do you reccomend the frequency response should be for the Woofer and also the Tweeter. They will most likely be in a .25 Cubic Metre Sealed Box, and will be about 6.5".
As you have proberbly realised I am new to this whole thing, I am therefore on a budget and I just want to build a pair of reasonable quality speakers. Any other suggestions are welcome.
Jeroth
As the Amp is 120W per channel, does this mean that the Woofer and Tweeter have to have a combined wattage of 120W(60 W ea) or does each one have to be 120W?. I will be using a 2 way crossover. And another thing, what do you reccomend the frequency response should be for the Woofer and also the Tweeter. They will most likely be in a .25 Cubic Metre Sealed Box, and will be about 6.5".
As you have proberbly realised I am new to this whole thing, I am therefore on a budget and I just want to build a pair of reasonable quality speakers. Any other suggestions are welcome.
Jeroth
In most musical situations when using a 2-way crossover even if the amp is near to clipping, assuming relatively standard power distribution and of course depending on crossover points and the type of music you listen to etc. about 40% of the output voltage from the amp will appear at the tweeter and the remainder of the voltage will appear at the woofer. This has the following effect.....
Of course, all figures below are generic and many assuptions have been mad but it should give you a general idea as to how the whole thing functions.
Now if your amp is 120W RMS into 8ohms and the speakers are also 8ohms, that is about 31Vrms output from the amp.
If 40% of that voltage (about 12.4Vrms) appears at the tweeter, the tweeter will receive about 19W and the woofer would receive about 43W. So, it can be seen that when using passive crossovers, not only does the music suffer because of the crossover but you also usually (more on this soon) lose about 50% of the output power. This allows commercial loadspeaker manufacturers to use drivers with a lower power rating. The exception to this is that if almost all of the input voltage is contained within a single passband. In this case, almost all of the amplifiers rated power can be delivered to a single driver frying it in the process.
Regards,
Daniel.
Of course, all figures below are generic and many assuptions have been mad but it should give you a general idea as to how the whole thing functions.
Now if your amp is 120W RMS into 8ohms and the speakers are also 8ohms, that is about 31Vrms output from the amp.
If 40% of that voltage (about 12.4Vrms) appears at the tweeter, the tweeter will receive about 19W and the woofer would receive about 43W. So, it can be seen that when using passive crossovers, not only does the music suffer because of the crossover but you also usually (more on this soon) lose about 50% of the output power. This allows commercial loadspeaker manufacturers to use drivers with a lower power rating. The exception to this is that if almost all of the input voltage is contained within a single passband. In this case, almost all of the amplifiers rated power can be delivered to a single driver frying it in the process.
Regards,
Daniel.
Well it depends on what type of music you like to listen to... generally, i'd probably go for a about a 60W - 75W woofer just to err on the safe side because some music is very bassy and so more than 60% of the total musical power (voltage) may go on the woofer. A 25W tweeter should be adequate as not much music has more than 40% of the musical power (voltage) located in the treble but a slightly higher rating wouldnt hurt.
Thanks!!
That has helped me tramendously.
When you say a 60W Woofer, is that the RMS or the MAX.Would you recommend getting woofers that are 50W RMS/75W MAX or should they be 60W RMS. And also, what frequency range would u reccomend for the woofer and tweeter.
Sorry for the amount of questions but I dont want to get the wrong thing and blow them.
Jeroth
Thanks Again!
That has helped me tramendously.
When you say a 60W Woofer, is that the RMS or the MAX.Would you recommend getting woofers that are 50W RMS/75W MAX or should they be 60W RMS. And also, what frequency range would u reccomend for the woofer and tweeter.
Sorry for the amount of questions but I dont want to get the wrong thing and blow them.
Jeroth
Thanks Again!
The wattage isnt all that important, although it does play a part, another thing to look out for is the sensitivity. Most DIY speakers are rated between 87-92dB, though for a 120 watt amp, less sensitivity will be fine.
For a simply 2-way, we really do need to get some exact budget figures.
As for the frequency responses, it depends on the drivers, lets start with a budget and work from there.
For a simply 2-way, we really do need to get some exact budget figures.
As for the frequency responses, it depends on the drivers, lets start with a budget and work from there.
Budget
My Budget would proberbly be about AUD$200 for the speakers, although i would prefer to have a bit of money left over,and then once I have those I will save for boxes, crossovers etc. Do you guys know any Online stores either within Oz or ones that offer shipment to Oz via money or cheque order, as i dont have a credit card.Thanks!
Jeroth
My Budget would proberbly be about AUD$200 for the speakers, although i would prefer to have a bit of money left over,and then once I have those I will save for boxes, crossovers etc. Do you guys know any Online stores either within Oz or ones that offer shipment to Oz via money or cheque order, as i dont have a credit card.Thanks!
Jeroth
Ok just a little clarification, when you said AUD$200 for the speakers, i assumed that included the drivers, crossovers, enclosures etc ... in short the whole thing.... if this is not the case please let me know. I dont have the links with me right now but once we decide on particular drivers, i can chase up the relavant links for you.
OK!
Here is the precise info:
I currently have AUD$200.00 in my account.I was planning on using this to purchase a pair of Woofers AND a pair of tweeters.
Then, start saving more money up and buy the rest of the things like cabinets etc in about a month.
If u think I would be able to get more than just the Woofers and Tweeters for this amount, PLEASE tell me.
Remember that I dont want the best system in the world, just reasonable quality speakers for my room.
Jeroth
Here is the precise info:
I currently have AUD$200.00 in my account.I was planning on using this to purchase a pair of Woofers AND a pair of tweeters.
Then, start saving more money up and buy the rest of the things like cabinets etc in about a month.
If u think I would be able to get more than just the Woofers and Tweeters for this amount, PLEASE tell me.
Remember that I dont want the best system in the world, just reasonable quality speakers for my room.
Jeroth
Well, this guy is in New York so it may be a problem, but I've had good experiences with http://www.zalytron.com
Under the budget speaker section, he has two kits that you might be interested in: the JML 5"TM ($99USD) and the German 2-Way ($110USD). The kits come with speaker drivers, crossover components and binding posts. Cabinets cost more, but you could save alot of money by building your own, particularly because of shipping cost, but I suppose you were planning on doing that anyway.
-Won
PS Welcome to the club
Under the budget speaker section, he has two kits that you might be interested in: the JML 5"TM ($99USD) and the German 2-Way ($110USD). The kits come with speaker drivers, crossover components and binding posts. Cabinets cost more, but you could save alot of money by building your own, particularly because of shipping cost, but I suppose you were planning on doing that anyway.
-Won
PS Welcome to the club
1st on the power thing. Except possibly in the Pro world, power handling of a speaker is not a very useful parameter. You are more likely to break a speaker if you have too little power then too much -- clipping, particularily with SS, is the enemy. Since music tends to be quite dynamic if you keep the peaks below clipping, then the average power levels will be quite low. If we assume that peaks are 20 dB above the average, and you are pushing the amp to its limit, but not clipping then the average power would be about 6 W. You do have to keep in mind that the rated power is into an 8 ohm resistor and into a real loudspeaker it is likely the amp won't be able to deliver quite as much power.
Generally (it varies quite a bit by type of music) the point at which there is a 50/50 power distrubution is at 300 Hz.
With a 2-way what is most commonly seen are systems with a 5 or 6" midbass and a dome tweeter with a cross-over between 2.5 and 5kHz. On these systems the woofer needs to handle the most power, but the tweeter is more likely to burn up if you run the amp into clipping.
Andy G is in Oz and has built a number of speakers from parts available there. He is also very helpful.
dave
Generally (it varies quite a bit by type of music) the point at which there is a 50/50 power distrubution is at 300 Hz.
With a 2-way what is most commonly seen are systems with a 5 or 6" midbass and a dome tweeter with a cross-over between 2.5 and 5kHz. On these systems the woofer needs to handle the most power, but the tweeter is more likely to burn up if you run the amp into clipping.
Andy G is in Oz and has built a number of speakers from parts available there. He is also very helpful.
dave
Clipping... http://sound.westhost.com/amp-sound.htm a little ways down has a few paragraphs on "Clipping Distortion", that will explain it better then I can in a post...
How Do These Look?
I Have been looking on the net and have narrowed a selection down, and have decided on Woofers & Tweeters.If these are the wrong things to get please tell me why(Wattage, Frequency Response etc).Remember that I have a 2 channel amp, with 120W RMS per/ch.Here is what I have chosen so far:
Woofer:
VIFA P17WJ-00 6-1/2" 8 ohms
Power handling: 70WRMS/100Wmax
Frequency response: 37-5,000 Hz
Fs: 37 Hz
SPL: 88 dB 1W/1m
Tweeter:
1" ALUMINUM DOME TWEETER 8 ohms
Power handling: 70WRMS/100Wmax
Frequency range: 2,500-20,000 Hz
Fs: 1,530 Hz
SPL: 92 dB 2.83V/1m
Thats what i thought will be fine but if anyone thinks otherwise, please post what should be different, things such as Wattage, Frequency Response etc.If you think this will work with my amp please tell me.
Jeroth
I Have been looking on the net and have narrowed a selection down, and have decided on Woofers & Tweeters.If these are the wrong things to get please tell me why(Wattage, Frequency Response etc).Remember that I have a 2 channel amp, with 120W RMS per/ch.Here is what I have chosen so far:
Woofer:
VIFA P17WJ-00 6-1/2" 8 ohms
Power handling: 70WRMS/100Wmax
Frequency response: 37-5,000 Hz
Fs: 37 Hz
SPL: 88 dB 1W/1m
Tweeter:
1" ALUMINUM DOME TWEETER 8 ohms
Power handling: 70WRMS/100Wmax
Frequency range: 2,500-20,000 Hz
Fs: 1,530 Hz
SPL: 92 dB 2.83V/1m
Thats what i thought will be fine but if anyone thinks otherwise, please post what should be different, things such as Wattage, Frequency Response etc.If you think this will work with my amp please tell me.
Jeroth
Yes I agree spend more time looking for a tweeter.... I dont much like metal dome tweeters as they are often harsh and just a word of warning, tweeters are often rated for system power (ie. amp output power) not for their own input power make sure whatever tweeter you choose is capable of what you want in this respect. Low Fs helps by taking some of the strain off the woofer (woofers dont do a great job of producing treble) and also allows for a more simple crossover.
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