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In Reply to: RE: Old glue formulation or newer formulation posted by Carl G on April 13, 2016 at 21:18:38
>>>you need about the same power to drive a mid/tweeter as is used for the bass panels<<<<
I probably wasn't paying attention when this was brought up in the past but I'd like to revisit this concept. I've got a pair of Emotiva XPA-1 mono blocks on each bass panel (high current, 1000 watts @ 4ohm), no way would I even consider my mids/tweeters getting pumped with those. I use a pair of UPA-1s which are about 400w ea @ 4ohm.
The reason I mention this is I just had a discussion with M3 Lover the other day regarding a pair of Parasound JC1s on the top end of my 20s and we both felt it would be a bit of an overkill. Although it would be possible to reduce the gain on my Marchand XO, I figure that would defeat the purpose.
Just my opine, YMMV.
Follow Ups:
The MAIN drive behind the 'how much power' question is Crossover Frequency. Full range requirements are certainly high. But, with the crossover used @line level, your amps are given QUITE a break and actually put out more power (apparent) 'in band'.
It gets a Little more comlicated with 3-way and up speakers or when you have a 2-way, like my 1.6 panels AND a sub.
Generally, the 50:50 point is considered to be 350hz. In NO case should the power to the bass end be less than maybe 30 to 40% of the total. If you crossed as high as 5000hz, you could easily make due with 100 watts for the highs given the kilowatt below crossover.
Too much is never enough
The mids of the 20-series will certainly not withstand hundreds of Watts without melting the Mylar. Remember the foli conductor is just 0.0005" x 0.1". They will also compress in its lower range as they cannot move very much air.
Those of you running 1000 W amps with Magnepan speakers. Have you ever measured how many Watts you really feed to the speakers? I would be surprised to see 1000 W in the bass, at least the in low bass where the fundmental resonance take up very much of the limited excursion.
Do foil conductors in the 20 series (0.0005" x 0.1") differ from those in the 3 series. If not it doesn't explain the failures in the 20.Xs. Additionally, there are probably fewer 20.s than 3.s in service.
Do the 20.s move less total 'corresponding' air than do 3.7s (or 3.7is) when given the same amount of 'juice', which might then tempt their owners to crank it up?
The 3.7/3.7i has different foil conductors, 0.001"x0.075". These can take more power. I am not sure if the 20-series mid have the thinner Mylar as the Tympani IVa had. Thinner Mylar will melt earlier/quicker. The mids of the 20-series are more "stressed" due to the lower cut-off frequency compared to the Tympani IVa.
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