DIY Speaker question
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Steve Irwin Unregistered guest | G'Day, I've just finished making my own 2ch 40WRMS amplifier thats 20WRMS x 2 and now I want to make my own speakers to go with it, I've found a good quality 10wRMS 8ohm speaker in a shop and I was thinking I could buy 4 of them, 2 to go in each box. My amp does 24WMAX into a 4ohm load so I want to wire 2 of these speakers together in parallel in order to get a 4ohm load. Now to my problem, if I wire 2 of these 10W speakers together will I get a total of 20W? Or will it still be 10W? (10w + 10w = 20w or 10w + 10w = 10w) So will the amplifier see these 2 speakers as 1 20w speaker and give it 20w or as 2 10w speakers and give them each 20w. -Cheers |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4593 Registered: May-04 | I hate to tell you; but speakers don't have watts |
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Silver Member Username: DiabloFylde Coast, England Post Number: 172 Registered: Dec-04 | Your amp will see a 4 ohm load. It won't know or care about the maximum rated wattage involved, as amps are usually not very intelligent. Are the drive units which you have found 'full-range' units? If they are not, then you will need to buy tweeters as well, together with an appropriate crossover unit, which will alter the equation a little. It is best to get the design sorted before buying the components.  |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4602 Registered: May-04 | Speakers don't got no watts and amplifiers ain't intelligent. Whatta hobby! |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 360 Registered: Dec-03 | >I hate to tell you; but speakers don't have watts Absolutely correct. For the time being, forget about watts. >Your amp will see a 4 ohm load. Well, 4 ohm nominal (average). This means, depending on the frequency being reproduced, it may be more or it may be less than 4 ohms. Will your amp handle less than 4 ohms? If the answer is no, then don't wire the drivers in parallel. > It is best to get the design sorted before buying the components. Correct. If you don't care about sound quality go ahead and throw a couple of drivers into whatever box you like and have fun. If you do want good sound quality then either build a proven design posted on one of the DIY speaker forums or get a speaker kit. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4607 Registered: May-04 | "So will the amplifier see these 2 speakers as 1 20w speaker and give it 20w " OK, whose gonna 'splain this one to Ricky? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4608 Registered: May-04 | "So will the amplifier see these 2 speakers as 1 20w speaker and give it 20w " OK, who's gonna 'splain this one to Ricky? |
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Steve Irwin Unregistered guest | >Well, 4 ohm nominal (average). This means, depending on the frequency being reproduced, it may be more or it may be less than 4 ohms. Will your amp handle less than 4 ohms? If the answer is no, then don't wire the drivers in parallel. According to the data sheet included with the IC it can be used to drive a speaker with a 4 to 8ohm impedance. I think the question your asking is - is it 2ohm stable? I don't think it is but I'm not to worried about this because alot of amplifiers out on the market arn't either and it doesn't seem to be a big issue after discussing this with some friends. >Are the drive units which you have found 'full-range' units? If they are not, then you will need to buy tweeters as well, together with an appropriate crossover unit, which will alter the equation a little. It is best to get the design sorted before buying the components. Well it ranges from 119hz to 9Khz so this seems good enough for me. The speaker I have in mind comes with all details necessary to build its enclosure so I'm not just going to throw it into a box and hope it works. >I hate to tell you; but speakers don't have watts Hang on I must of missed something here, If I have a 50W amp and I want to hook a speaker to it wouldn't it have to be rated somewhere between 1 and 50W to work correctly? Havent you ever seen a speaker in a store that says 20W on the back of the magnet? Could you please be more specific. >Your amp will see a 4 ohm load. It won't know or care about the maximum rated wattage involved, as amps are usually not very intelligent. >Speakers don't got no watts and amplifiers ain't intelligent. Whatta hobby! >"So will the amplifier see these 2 speakers as 1 20w speaker and give it 20w " OK, who's gonna 'splain this one to Ricky? It seems you have misunderstood me, I know amplifiers arn't intelligent beings that can desifer complex equations at the touch of a button or something like that I'm just asking if the speakers I have in mind a right for the amplifier I built! People I'm still learning could you please tell me if my idea looks correct? |
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Silver Member Username: DiabloFylde Coast, England Post Number: 179 Registered: Dec-04 | "Well it ranges from 119hz to 9Khz so this seems good enough for me" No, it isn't. I'm 53 years old, yet I can still hear slightly above 16 khz. If I live to be 100, then my hearing will probably give up at 9 khz. If you are 100 then your speaker idea is probably okay. Otherwise, you should give your speaker intentions more thought. I will try to find some links to speaker design and post them. Nasty old world, ain't it? Rgds, diablo |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 362 Registered: Dec-03 | Wattage ratings tell you how much power the driver can typically handle. There are generally two ratings associated with this. How many watts they can handle continuously and how many peak. This has absolutely nothing to do with how much power the amplifier is going to put out. The power output of the amplifier is going to depend on what's happening within the entire circuit. The only reason to be concerned about the wattage rating of a speaker is if you're concerned the amplifier will put out more power than the speaker can handle. Can you connect a speaker rated at 5 watts to a 35 watt amplifier? Sure, I do it all the time. Just don't turn the volume up too high. So, does your 20 watt per channel amplifier put out 20 watts all the time regardless of input? I don't think so. What it may do is deliver 2 or 3 watts to play a quiet passage then suddenly jump to 10 watts or more when some large dynamic shift in the music occurs. This happens often with classical music, btw. Bottom line, the drivers you're looking at will work ok. Since you've described what sound like cheap mid-range or possibly TV speakers you're unlikely to damage either the amplifier or the drivers with your proposed setup. It's not going to sound very good though. A much larger concern should be the impedance of your speakers and if the amplifier can drive that load satisfactorily without being damaged. The question you should have asked has been answered. If you take two drivers rated at 8 ohm nominal and wire them in parallel you will have, theoretically, a 4 ohm system. If you wire them in series you will have a theoretical 16 ohm system. Impedance ratings of drivers are an average of the impedance curve measured over the drivers operating range. An 8 ohm wide range driver, for example, may range from 40 ohms at 15kHz to 5 ohms at 300Hz and rise back up to 40 ohms at 60Hz. If you wire two of these in parallel what do you imagine your impedance will be now? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4615 Registered: May-04 | Uh, let's see ... that's 8 over 40 multiplied by 15,000; subtract the 300 and divide by 40; toss out the 60 'cause it screws with the equation ... and "Now to my problem, if I wire 2 of these 10W speakers together will I get a total of 20W? Or will it still be 10W? (10w + 10w = 20w or 10w + 10w = 10w) So will the amplifier see these 2 speakers as 1 20w speaker and give it 20w or as 2 10w speakers and give them each 20w?" BUT! "I think the question your asking is - is it 2ohm stable? I don't think it is but I'm not to worried about this because alot of amplifiers out on the market arn't either and it doesn't seem to be a big issue after discussing this with some friends." And, of course, "Well it ranges from 119hz to 9Khz so this seems good enough for me. The speaker I have in mind comes with all details necessary to build its enclosure so I'm not just going to throw it into a box and hope it works." And, in summary, "I'm just asking if the speakers I have in mind a right for the amplifier I built!" Steve, we understand you're still learning; but you aren't learning the right things. As a matter of fact, you seem to be somewhat resistant to learning. You ask if I've never seen specs on the back of a speaker. Of course I have. And I have a bit of an idea that when a speaker says it will drop the impedance load down beneath the safe operating conditions of an amplifier, you just don't blow that information off because it doesn't suit your purposes. And the justification that other amps are also unstable at that load is just not thinking this through, Steve. It seems you want to do this combination no matter what information you get. In that case, go ahead. Stop reading this answer as of now. The nice thing about that approach is when it blows up, it will be easy to repair since the parts that need replacing will be surrounded by scorch marks. That does make troubleshooting easy. You're not going to learn very much from this group of friends you have who don't appear to know much more than you. I do wonder why you came to this forum when you have such experts to get information from. Here's how you learn something, Steve. You read quite a bit about what you're trying to do and you ask a lot of questions of people that know a lot more than you do about the subject. Then you go read some more to figure out how what those people tell you fits into what you already know. Then you ask more questions. Then you begin to experiment and you learn from your mistakes. Then you read and ask what went wrong. You want to jump in at the experiment stage. OK. But thinking you have the answers because your friends told you to ignore specs isn't smart. Having plans to build a box for the speaker doesn't mean you're not still flying blind. Even if it works, you won't have a clue as to why it works. But, as they say, we are where we are and we might as well address the issues at hand. Speakers don't got no watts is the first thing to learn. Recommended wattage means little to nothing in the actual world of audio. It is a matter of what signal you put into the speaker and for how long. It is far easier to blow up a speaker with an amplifier that has less power than the "wattage" of the speaker than it is to damage a speaker by using too much power. Remeber that, Steve. It's one of the most important lessons in audio. It's especially important if you want the system to play loudly. Your question about will the amp see a 20 watt speaker is poorly phrased because you have a poor understanding of what is important and how to put together what is important. That's why your still learning, right? Combining speakers will increase the overall power handling of the system; but it doesn't have a simple equation that you can plug in and get this many Y's as an answer to this many X's. Why? Because it's easier to blow up a speaker with too little power than ... yada yada. No, the system will not become 20 watts. Obviously from the answer Timn8ter gave you, you should understand that the question "will the amplifier give the speakers 20 watts" is not the way to ask the question. The problem here is there's no way to get from what you asked to what you should have asked. The amplifier will put out the amount of power required by the signal depending on where you have the volume control set. If the amp can produce 24 watts, it can produce 24 watts and no more. It will produce varying amounts of wattage depending on the signal until it reaches its maximum power output. When the amplifier can no longer produce enough power to reproduce the signal without going into distortion, you will blow up a speaker if you don't turn it down. The next question is; should you be concerned that the system might drop below the impedance recommended for the amplifier? YES!!! I don't care what your friends say. Haven't you ever seen the specs on an amplifier that say "DON'T USE THIS AMP WITH A 2 OHM LOAD CAUSE IT WILL BLOW UP!!!" Or something to that affect. You are not making a wise decision here, Steve. But, like I said, it will be easy to troubleshoot. As to the plans for the box, they don't have diddly to do with whether the amplifier will drive the speaker system you put in the box. If you don't understand why that is from what you've been told here, then we've wasted a lot of time. The final question you've asked is, "if the speakers I have in mind a(re) right for the amplifier I built." Well, actually from the information you've given us, we can't tell. As a single speaker it would appear the speaker won't stress the amplifier. As a system you would appear to be treading on thin ice. But this does seem to be a fairly cheap driver system you're looking at, so replacing the system shouldn't be terribly expensive if it doesn't work out. On the one hand I would tell you to go ahead and try the system if you'll learn from the experience. On the other hand if you'll come away from the experience with no more knowledge than you have now; I would say you're foolish to try what you are suggesting. Sorry we can't give you the answer you want in a two sentence reply; but you aren't asking the right questions to get a two sentence reply. If you want to understand what question you should ask and why you should ask those question I would suggest you spend some time with web sites like the ones at: http://www.madisound.com/ http://www.partsconnexion.com/ http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=29 And, if you get more serious about learning from the experts, then you can look into this: http://www.crutchfield.com/S-2RW1MScSlJ0/cgi-bin/prodview.asp?i=224BKAA60 Tim can probably provide you with more links that will allow you to learn what is needed to make these decision about what works and what doesn't. If you read this material, you become the guy your friends come to for advice. If you just stick speakers in a box and hope for the best, you'll always get answers like this from guys like us. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4616 Registered: May-04 | http://search.yahoo.com/bin/search?p=diy%20loudspeakers |
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Steve Irwin Unregistered guest | Well sorry, I thought I asked a preety easy question in my first post, I'm not an expert on amplifiers or speakers and so arn't my friends but from what I've gathered an amplifier that can put out 24WRMS should be able to power a speaker rated at 10WRMS - simple enough? maybe even 2 of them to get 20W? Jan Vigne thanks for the long reply I will try to ask "the right" questions more often in future, and yep I am experimenting with this project I have been scince the start. I haven't bought any speakers yet but the one's I did have my eye on looked perfect for the job (10w 8ohm). I just got confused as to wether the amplifier would put out 20W to both speakers or 10W to both speakers and not stress itself, but now I know. Ok I did more research on the frequency range and diablo your right maybe 9khz isnt enough to get the full range of sound - back to the drawing board. -Steve |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4626 Registered: May-04 | Steve - Don't take this wrong, but the more you learn, the better your questions will be. Like they say, there are no stupid questions. Read some of the information and you'll figure out what you need to ask. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 367 Registered: Dec-03 | A good way to get started in speaker building is to use full range drivers for your first project. You can concentrate on the basics of power handling, impedance, enclosure volume and port tuning without having to get into crossover design and the need for sophisticated measurement equipment. I could make driver recommendations if I know what country you're in. Is it really Australia? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4631 Registered: May-04 | T8 - So you think a full range driver is easier for the beginner than a simple two way, sealed box with a cap on the tweeter? Here's my take on this - and like I said on another thread, I don't fully understand the world of full range drivers that are populating the speaker market right now. A full range driver from what you've said, Tim, and what I've read elsewhere, is going to require some low frequency compensation or the decision to limit low frequency extension. The FR driver should have some baffle step compensation to eliminate some irregularities in the overall response of the system. And, ultimately, the FR driver will require some additional assistance, in the form of another high frequency driver and a X-over, to extend the response to generally acceptable fidelity. Finally, the FR driver will be happier in a vented enclosure of some sort which will require some knowledge of port size, box dimensions and driver specs beyond 10 watts/8 Ohms. On the other hand a sealed box is the simplest form of enclosure to build first time out. (As many a budding speaker builder has ventured; with enough screws and silicon caulk, you can, sooner or later, build a sealed box.) A first order X-over has a good chance of sounding OK with decent drivers and the first time builder's results should be good enough to encourage more experimentation. Again, not arguing; just asking. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 369 Registered: Dec-03 | Simple. I was thinking a first time builder, if they have access to Fostex drivers, could go to the Fostex website and get plans and drivers for something relatively inexpensive and easy to build that would probably sound ok. That's about all the thought I put into it. The Fostex website includes options for adding a tweeter with just a cap and maybe an L-pad if someone wanted to do that. http://www.fostexinternational.com/docs/speaker_comp/rec_enc_1.shtml I don't know if Steve has access to Fostex drivers way out there in Alice Springs though. |
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Steve Irwin Unregistered guest | What is your opinion on Ribbon Tweeters? I had a little read through an electronics magazine from a distributer here in Australia (Yep Aus) and I found 1 ribbon tweeter in the catlog for $25.60 with a frquency range staring at 9khz ranging to 40khz, it said in the description these tweeters usually go for $50 - $100 and even more and that they had ordered in a big bulk lot of these from a company in the USA but they wouldn't say who it was. They don't look to flash in the picture but their saying this is a once in a life time chance to get them cheap. I only a quick browse of the specs (I was on lunch break) but I can tell you they are 8ohm 20WRMS and 50WMAX, the catalog is from an electronics distributer called Electus. BTW I live on the Sunshine coast in QLD not way out in the bush. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 372 Registered: Dec-03 | Gotcha. Didn't know if you were truly an Aussie or just pretending. Can't be too sure on the Internet. Like any driver it's going to depend on how it's designed and constructed. The advantages of a ribbon are it's low mass and directivity. Because there's less mass it can respond faster to the signal than traditional tweeters. This doesn't mean it will have less distortion however. Because of its narrow dispersion pattern you'll have to sit pretty close the the "sweet spot" to get good performance. On the other hand, directivity can help deal with early reflections from walls. The biggest downside to ribbons is they are extremely fragile. Fast air pressure changes can easily damage them, such as quickly closing the door of your listening room. The other downside, perhaps, is ribbon tweeter require high-order crossovers, probably best with a 4th order. They can be easily damaged if played below their intended frequency range. Unless you have the proper software and measurement equipment I would recommend against trying to "wing it" with this type of system. Chances are you would end up with pile of dead parts unless Electus has a box and crossover design already. If you want to get into this hobby, which is lots of fun I think, you should check around with the DIY guys. I know there are many in your area. http://www.diyaudio.com |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 4638 Registered: May-04 | To my recollection most true ribbon tweeters (and there are psuedo-ribbons out there), apart from the concerns T8 has already stated, have a reasonably high capacitance compared to a conventional dynamic driver (dome or cone). If I understood correctly from an earlier post, the amplifier you've built uses IC outputs. Unless these outputs are heavily buffered, the chances the IC's will enjoy driving a high capacitance load are not that great. Somewhere around you enjoying your last root canal. Once again you run into a situation where watts and Ohms might not be enough information. |
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Bronze Member Username: PbdrPost Number: 46 Registered: Apr-05 | Tim, You seem to know quite a bit about speaker building (I have checked out the Ling review, and wish I had seen that a couple months ago..) and full-range/fostex drivers. I have been toying with the idea of full-range driver speakers, possibly putting something together myself (just one of those morons who has to "get his hands dirty", comes from too much time in the lab). Are their good full-range drivers out there? Are fostex the good? I read some review of Omega speakers (which use fostex) and noticed that they have a LONG burn in time and need to "warm up" with use. Anything there. I will back off for now and let you answere before asking more. Steve, not trying to Hijack here, figured it would be ok to "borrow" since this might interest you also. |
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Silver Member Username: Timn8terSeattle, WA USA Post Number: 374 Registered: Dec-03 | Fostex is generally held up as a good value for the money by the full range driver crowd. They are usually forward in the mid-range and need low end support either from a suitable enclosure like a rear loaded horn or a transmission style enclosure, or by a subwoofer. There are some that like putting Fostex drivers into sealed boxes or open baffles and supplementing with subs. If you would like to try your hand at building a single driver design I recommend Bob Brine's FT1600 which uses the Fostex FE167E. Many of these have been built and the owners are all pretty happy. http://www.geocities.com/rbrines1/Pages/FT-1600_MkII/Main.html Plans are $25 and the drivers run about $68 ea. You may enjoy reading this article too. http://www.6moons.com/audioreviews/firstwatt/firstwatt.html This is mostly Nelson explaining his philosophy but he gives a brief description of several full range drivers. If this is more than you wanted to get into let me know. I have some suggestions for smaller systems. |
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