Advice on small loudspeakers
Reply #13 – 2013-02-11 15:44:26
I read on that site that uneven orders are the recommended (so it would be either 1st or 3rd), that would avoid the polarity inversion trick. Yes, that's what the site says, however 2nd order (and 4th order, but these do not require polarity inversion AFAIR) are used pretty often anyway.It comes to my mind now that the box is sealed. And I just read the words heat & dissipation... It is not that I need ventilation, right? Then your box wouldn't be sealed anymore. You theoretically could use a radiator, this is used for amplifiers of more powerful powered speakers. In your case it should not be necessary though. First, the actual power delivered to the tweeter will only rarely be full 20W, unless you are actually trying to fry the tweeters (or resistors). Second, if there was no attneuator network, all 20W would go into the tweeter, which would also convert much of it into heat. Speakers are not very efficient and at best a few % of electrical power is converted to acoustic power, the resto goes into heat. So I don't think this is going to be a serious issue, although I don't guarantee this. A tweeter is exposed to the outside, so it can loose some heat more easily.Ok, so we have these 1W or 2W resistors which are huge... we're talking about those, right? I entered 20W per channel, based on the amplifier power... I am not sure if I have done this right. However, I see weird results like one resistor being 18W. A 20W resistor would be the huge squared porcelain resistor. Is this more or less the deal? Your problems results from trying to match two drivers of very different sensitivity. I think that the proper solution is to find better-matched drivers. Or go with a large resistor. Now, I had my try into bulding (or rather rebuilding speakers) years ago, I learned quite a lot then, and I passed most of I learned to you. I think it would better for you if you found a dedicated speaker/DYI forum and ask your specific questions there, like whether it makes any sense to try to match these drivers, or specific questions about circuits. People who actively build speakers at this time will answers such questions better than I ever could.