about speakers and impedance

[dpb]

On 12/31/2014 8:59 AM, Pico Rico wrote: ...

Not Google but the browser url display...

[Pico Rico]

you are right. Now I see the problem exists with both google and yahoo searches.

I don't see anything that leaps out at me in Firefox to change - any suggestions?

[Les Morpion]

This is what google gave me:

[clare]

Only if you tried to push too much power through too many speakers.

Yes, they still use 70 volt "distribution" outputs on many PA systems. The output transistors are made to handle the high voltages directly. Lots of Bogen systems out there with direct outputs to 70 volt line.

If you read the fine print it is "1000 watts peak music power" aka "Peak Power Output" and in even finer print it will say something like "20 watts RMS per channel".

There is no established standard for measuring "peak music power" or Peak Power Output"

As for getting into legal trouble, The Federal Trade Commission is putting an end to this with Federal Trade Commission (FTC) Rule 46 CFR

432 (1974), affecting Power Output Claims for Amplifiers Utilized in Home Entertainment Products.

[clare]

Use IE11

[dpb]

On 12/31/2014 10:14 AM, Pico Rico wrote: ...

right click/copy I think doesn't use the shortened display altho at the moment I couldn't get a long-enough url to show to try it...

[Pico Rico]

It seems to only happen for .pdf links.

[Pico Rico]

no, I am wrong.

and the problem does not occur in IE8, just Firefox.

[trader_4]

Oh no, impossible. A MSFT product is actually better than an alternate browser, at least in some respects?

[Pico Rico]

yeah, but I see it only works (wrong) when I use Google or Yahoo as the search engine. Bing and Duck do not have this problem in Firefox.

will it never end?

[Tony Hwang]

Hi, Most 12V car amps can load 2 Ohm speakers. They are not AB1 or AB2 class amps. D or G class with MOSFETs. Like I said my old Quad PA can take piece of wire without suffering damage. Frequency response is almost flat from DC to ~20KHz.

[Jerry.Tan]

Bogen seems to have been the leader in P.A. systems for many years. Since I have not worked with this sort of stuff in years, I didn't even know the company was still around. But this comes as no surprise, since they always made quality equipment.

Somewhere in my garage, there is still a Bogen amp from maybe the 1950s. It's a tube amp. It did work, but has not been plugged in for at least

25 years. I'd hesitate to plug it in, before replacing the power supply capacitors. It was no big power, probably about 50W. I got it from a building that was being demolished. That building was used for livestock auctions. I suppose it was the PA for those auctions.

Back in the 60s and 70s, Peak Power was generally about DOUBLE the RMS power. That made sense and was probably fairly accurate. I had a power amp back then, rated at 100W RMS, and it said 200W Peak. I used it to do sound for some Rock bands from that time period, along with a mixer board.

About time!!! I'd be surprised if that boombox output is more than 10W per channel RMS. That would mean 20W peak per channel, or 40W total Peak. That 1000W rating is pure bullshit. There is no 5" speaker that could handle that power, and no D-cell batteries that could power it. (or a 2" Wall transformer power supply).

I still remember back in the 70s, when I did sound and lighting for rock bands, far too many times the bars and small clubs that hosted the bands did not have enough breakers to power the sound system and other equipment. Granted, our stage lighting sucked most of the power, but the amplifiers still needed a good 15A (preferably 20A) dedicated outlet.

We finally got a breaker box, mounted it on a board, and added a bunch of outlets. Then there were 3 heavy cables with well insulated large alligator clips, which we'd tap right off the MAINS. But there was an extra charge to the club for doing that, so some of the clubs did update their wiring after awhile.

Today's sound systems for bands need even more power than back then, but most modern stage lighting is now LED, so that offsets the power demands. And most places that host live music these days seem to have a whole bank of outlets at the stage. I guess they finally wised up!

[Jerry.Tan]

After getting the correct URL I downloaded this and it's a very good and interesting article. I'm glad it went back to the history involved, because the earlier systems were the ones that I was familiar with, and I did have to work on a few of these systems in large buildings, where a speaker would stop working or sound bad. Most of the time it was a faulty speaker, but I did change a few transformers. Thanks for the link.