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@provenrad
Hey guys - the speakers are sitting in Push. I had a quick look at the specs and only remember that they are 92db sensitivity. Sorry, I can't remember the impedance.
If we wire each side with a 3-series/3parallel array, they the sensitivity (efficiency} will go up a fair bit, without affecting impedance AFAICS. If they are 8 ohm, they a 5 parallel/2 series grid will reduce impedance to 3.2 ohm, which would help loudness without affecting the amp too much.
I reckon peizo (horn) tweeters would be good for top-end - we dont need a X-over for them, and they are quite efficient, though only a few are as good as regular tweeters in terms of fidelity / reproduction. cost 5-10 gn each
For low-end, a couple of high-efficiency 8-12inch drivers would be necessary. I have seen some available for 30-60 quid each that look promising. If we cheap out on these drivers, we will have to get more of them and do the same as for the mids (i.e. grid/array) Not ideal, as it means more weight and more baffling. Crossover is required, if not at least some signal filtering.
I have also been looking up some amp stuff online; the t-series amp6/9s from 41hz are very popular for portable setups, which means some of the research has been done for us. Efficient, run off 12v, small... the amp6/9 kit cost from 35-75 Euros depending.
If Jono's amp needs >12V after the transformer (most home amps txs are tapped at >30V it seems) then it might be a no-go without some more electronics, and that would be inefficient.
Does anyone have a car stereo that we can nick for testing? This would be less efficient, but at least get the music started ASAP.
Regd. power supply. The car battery is available, but it will die with deep cycling (designed to be topped up almost constantly.) Since it is virtually new, I am a loath to kill it so quickly. And lug it across London for the privilege.
I have a couple of SMART 6v Sealed Lead Acid batteries possibly somewhere that would be lighter and have a charger too. Perhaps the forum can supply more of these for free, as most people are using better batteries these days.
Ideally we would get hold of a SLA battery from a mobility scooter or similar from Maplin etc, which would be lighter than a car battery and we can parallel them if they capacity is not enough. cost 17-20 quid each.
Or a deep cycle battery from a boat (JB) would be good so we don't have to worry about efficiency too much... they cost more.
anyhoo... back to the sunshine.