Re: Battery powered amplifier from car speakers and booster amp?



First, a fiddle. It has a piezo bridge pickup but has its own preamp, both made by Fishman. Only needs amplifying outdoors.
Second, a traditional Japanese WX7 and VL70m pair. Yhe WX7 is a midi keyboard that looks and plays like a clarinet, the VL70m is a "Virtual Acoustic Tone Gnerator" that produces, apart from others, passable bassoon and bass clarinet sounds. Runs off 12v.

Yes. I understand that these, along with other percussion instruments, produce quite a lot of peak energy.
I've been using someone else's "Pignose" 20 watt amp. It has a single 6.5" cone that clearly doesn't manage some of the higher harmonics. Playing the instruments through the home hi-fi (ish), they sound very much like the real thing. Played through the Pignose, except in the octave around middle C, they both sound like ....... The upper ranges of the clarinet and bassoon sounding very electronic and similar. Mind you, it still sounds better than a Yamaha "portable pa" box.
The advantage, I thought, of the car speakers was their relatively wide frequency response and compactness.

Thanks very much!
Sam
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12v 7ah SLA.

I should have said the speakers are actually only the drivers. I don't think fibreglass would work very well for a cabinet unless it was very thick.
I don't want to play under water, the dancers get a bit soggy and rebelious. I just want to be able the resist the odd shower without wrecking the cones.
Sam
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Is that a type of battery? I assume it is by the 'ah' description. A 100% efficient 200 watt amp running at full power would flatten it in minutes. And car booster amps are anything but 100% efficient. For a reasonable portable outdoor system which will run for a couple of hours reliably, you're looking at a decent sized car battery - say about 45 Ah. You don't want to flatten the battery if it's a lead acid type as this will shorten its life.
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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wrote:

And they're also no good for connecting to pressure pads!
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On Wed, 21 Jan 2004 10:27:48 +0000 (GMT), Dave Plowman

Sealed Lead Acid A 100%

Indeed, I don't expect to need much more than 10-15 watts. It's just all I have at the moment is 100 watts. If all works well I may well change it, but not unless I have to.

This is not "continuous" music like playing a record but a single instrument. It makes a lot of difference to the power consumption. I've run a 20watt amplifier for 4 sessions of 2 hours on an old 4ah SLA.
Sam
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On Wed, 21 Jan 2004 10:27:48 +0000 (GMT), Dave Plowman wrote:

Yes, a "Sealed Lead Acid" type. Commonly found in alarms systems for backup power and in small UPSs.

Quite, my commercial UPS has two 12v 7A/Hr batteries in series. It's currently telling me I have an uptime of 4 minets at 82% load or about 575W.

Unless it's in your homebrew standby power system. B-)
A proper "leisure" battery will survive deep discharge and are available in SLA format. You do need to take care with charging compared to an open wet battery.
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I hope it never gets used. But a PA system surely would?
Latest mod is to the invertor so I can set the dropout voltage to choice.
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Sadly car speakers don't come with proper specs, the best I've found show "frequency response" and "sensitivity". I would hope that they are designed for fairly small enclosures but I've seen a frequency response quoted of 30Hz - 32kHz.

That's just what I wanted to know.

The one's I've got have an add on grille, presumably to protect them from foot damage in a car door.
Thanks Fergal.
Sam
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wrote:

dimensions &

designed for

30Hz -

cubic
add
the
the
box
Try
start.
stuck
well,
transit.
foot
I found some useful stuff on making fibreglass speaker enclosures and other aspects of car hifi which would be applicable to you here:
http://www.jlaudio.com/tutorials/index.html
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Yes, thanks. I'd looked at it some time ago but had forgotten. The port bit is certainly interesting.
Sam
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Yes, thanks. I'd looked at it some time ago but had forgotten. The port bit is certainly interesting.
Sam
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