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Old 4th January 2007, 06:59 PM   #21
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Quote:
Originally posted by panomaniac


I can't find that driver on any English language site, not even Beyma. Is it still current?
I'm actually not sure. I haven't really found any solid info on it anywhere, but the thought that it could be discontinued hadn't occurred to me.

FWIW, lautsprechershop.de sells this driver in a Cyburgs Viech kit, but I can't find this particular driver in the list of Beyma drivers that they carry.

These guys sell it though:
http://spectrumaudio.de/breit/beyma8AGN.html

Looking at the frequency graph, the 60-18KHz number looks kind of odd. But people seem happy with it in a horn, so it can't be all bad.
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Old 4th January 2007, 07:28 PM   #22
Pano is offline Pano  United States
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Thanks! The FR chart does not look too bad for this type of driver. BTW, it's a really high Qts driver, might not work well in a small portable box. Might be fun for OB, tho.

These guys http://www.prosl.com/ in Belgium have it for 29.50 Euros, tax included! Not bad.
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Old 4th January 2007, 08:27 PM   #23
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Another thing to consider in seeking volume from a portable device is how strong the input signal is.

iPods and most portable CD players these days are designed to have long battery life, which means the output signal is less that it could be. Putting a small battery-powered headphone amplifier between source and amp, preamp fashion, can make a louder noise at any given amplifier wattage rating.

In my experience, some of the DIY versions have grounding/power rail issues that conflict with the Sonic Impact (at least if you're trying to power them off the same 12v source). I just got a Little Dot Micro that seems to work just fine for this purpose, though. Definitely makes more noise.

--Buckapound
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Old 5th January 2007, 04:21 AM   #24
Magicdj is offline Magicdj  United States
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XSpunge - That looks awesome! I bet with those horned tweets it has a nice SPL output. Any idea what SPL @ 3 ft?
Is that amp you built the same output as the T-amp? I'm a little confused with the tripath amps, I heard that at 12V the most you can get out of them is the same as the T-amp? I checked out that link for that Blaupunkt (Tripath) amp and it has a rating of 150W X 2??? The T-amp is like 10-15W? Maybe someone can explain? (with out - flux capaciter lingo ) (BTW- raintalk thanks for the tip - I'm very tempted to get that amp!)

I never tried batteries in the JVC... I heard it sucks them down too quickly. JVC is bi-amped 6W full range 20W to the subs... I do have to admit in my bathroom that thing hits pretty hard... Not outside though

I was considering the Li-ions, but I have little experience with them. What cells do you use? What charger?
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Old 5th January 2007, 04:41 AM   #25
Pano is offline Pano  United States
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Car amps use a DC-DC step-up device to increase the voltage. There is only so much power you can get out of 12V into 4 or 8 ohms.

In the old days the tube car amps did the same, most of them.
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Old 5th January 2007, 05:48 AM   #26
Xspunge is offline Xspunge  United States
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Thanks for the compliment. At 3ft its pretty loud at max volume outdoors. You can hear it across the fields where I use them at, so if you were to build a box like it, using an Amp32, or Amp6 Basic you would get similar results (using 4ohm speakers with similar efficiency... 95db for the "woofers" 93db for the mids and allegedly 104db for the tweeters but I doubt that number) I don't have any testing equipment so I can't give quantitative numbers regarding actual volume. All I do know is that it will drown out an Altec Lansing IM-7, a portable boombox for the iPod.

The amp in my pics are 41HZ models, the AMP32, and AMP 6 Basic which is essentially the same thing as the 32 but in a larger easier to solder kit. Both have the same power output and both have a max voltage input of about 14.x volts. ANy higher and you risk ruining the chip. Also, the extra voltage is given off as heat and not used to power the speakers so you don't gain anything by using a higher voltage source you just get a hotter main chip.

The 41HZ amps all have a higher rated power output than the Sonic T Amp (which I also have) and can say that the volume output is indeed higher (when using the same battery and same speakers at full volume) The AMp 32 and the AMp 6 Basic are rated at 25W x 2 channels max output. However that is at clipping and distortion, real world output is lower maybe 15-20W (my non scientific estimation) So it could probably out do the JVC, and especially so if you get efficient speakers at 95dB or higher. The Sonic T Amp will put out a real world output of about 10w with clipping, so figure a little bit less for full volume without distortion.

Don't know about the blaupunkt amp, so I can't help you there.

Regarding batteries, you can find some Li-ion cells on ebay pretty cheap. The ones I use are size 18650 and have soldering tabs so you can put a pack together easily. Each cell is 2400mah, 3.7v but in actuality they will put out 4.2v per cell fully charged so thus you will get 12.6v out of a 3 cell pack. Just solder them in series to get 12.6 volts (although they are called 11.1v packs), then make another 3 cell pack to double the run time. If you want you check the link to one of the auctions for cheap Li-Ion Cells

http://cgi.ebay.com/New-Lithium-Ion-...QQcmdZViewItem

Just disconnect three cells to make 3 packs of 3 cells. Then you can parallel them all to get massive run time.


The charger I use is from www.batteryspace.com and its cheap especially for LI-Ion chargers. It has auto cutoff and you will have to solder on your own connector, but that is easy to do too.

http://www.batteryspace.com/index.as...OD&ProdID=2488

It is listed as a 4 cell charger, but underneath that silver sticker is a switch you can select for the 11.1v pack (12.6v). That is the exact charger I use, and I soldered on a connector for my battery.

You can also use prismatic (flat) cells from Li-Polymer/Li-Poly batteries. They are rectangular and are very thin and very light. Same voltages apply to them 3.7-3.8 rated but real world 4.2v per cell. You don't have to worry about discharge rate since D or T Class amps won't draw anywhere near the amount needed for other applications so you can go with normal or lower output cells which are cheaper than stuff needed for RC, wheelchairs, or other high drain devices.

I have an RC Helicopter battery that I sometimes use in a pinch if my main battery isn't charged. It is a Li-Poly battery that is 11.1v (12.6v) and I put the same connnector on it.

I can help you out with instructions as to how to construct a pack if you choose to go with one.

But if you don't want to deal with making your own battery, then Sealed Lead Acid is the way to go. Cheaper, high capacity, but they weigh 5-10 pounds instead of 10-12 oz.
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Old 5th January 2007, 11:54 AM   #27
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Quote:
It is listed as a 4 cell charger, but underneath that silver sticker is a switch you can select for the 11.1v pack (12.6v).
You mean under the sticker that says "Never remove this label!"

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Old 5th January 2007, 02:32 PM   #28
Xspunge is offline Xspunge  United States
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Yup, that's the one! You have to remove that to get at screws so you can take the charger apart, at least I had to in order to add my connector. I wanted to make absolutely sure the polarity was correct... you don't want to short Lithium based batteries.

And as a bonus gift, for your removal of the "Do Not remove sticker", you discover the sticker is hiding a selector switch for 3 or 4 cell packs. The charger says to use it only with 4 cell, but after testing it with a multimeter and then testing it with both my 3 and 4 cell pack, it works exactly the same for both. Voltage cut off works fine and auto cut off does as well.

They sell the same charger without the sticker and call it a "Universal Charger" for more.
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Old 16th February 2007, 11:02 PM   #29
shr-t is offline shr-t  Finland
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Quote:
Originally posted by Xspunge
[B]What type of batteries are you using to power that boom box? I would suggest 12v Sealed Lead acid. They are cheap, can supply enough power for just about all amps (especially the Tripaths) but they are heavy. I would also suggest Li-Ion or Li-Polymer since they are much smaller and lighter, but of course are much much more costly.

I can assure you that if you are using Alkaline batteries with that JVC then it will start to clip and distort at high volumes. And to make matters worse when the batteries run down the max volume decreases and the clipping starts at lower volumes until the batteries run out. You also have to figure in the high cost of constantly replacing those things.

Can you please explain, why are Alkalines a bad idea?

Because of this?: (from Wikipedia)

Quote:
Unlike NiMH rechargeable batteries, alkaline batteries are normally not sold with a nominal capacity. The reason for this is that the capacity of an alkaline battery is strongly dependent on the load. A AA-sized alkaline battery might have a capacity of 3000 mAh at low powers, but at a load of 1000 mA, which is common for digital cameras, the capacity could be as little as 700 mAh.
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