calculate volts and amps from 1000 watt head into 4 ohms

#44
agedhorse said:
drummers often cause an accidental unplug incident with the amp powered up and playing. This can certainly damage many amps.
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I think I just found something about which I disagree with agedhorse. :)
Must be a new moon or something.
I wouldn't say it happens, "often"... or I'd never be able to hide that many drummers' bodies. :laugh:
To me "never" is most accurate.

Altho at an outdoor gig more years ago than I want to admit I did finish a set, walk around behind where we were set up, just as one side of the PA stack came down, thanx to a drunk toppling into it. No damage to those Altec or JBL or whatever they were, cabs and speakers. Quarter inch too, as that's all there was back then when dinosaurs roamed the land.

Merry Christmas.
 
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#45
JimmyM said:
Hoo boy! Time to separate the wheat from the chaff, and what better day to do it than Christmas? :D

Yes, speakons are a more reliable and robust connection, BUT....

1. If you are getting the PF cabs that have tweeters, there absolutely will be a PC board for the tweeter, and Andy is absolutely right that it could cause problems for you trying to add a speakon. In addition, there's every possibility you could botch the conversion and end up creating a hole that air can leak out of, which will make your cab sound distorted, or you could ruin the plate in other ways.

2. Andy is right that replacing all the wiring in the cab is useless, and going to such a heavy gauge could cause major problems with soldered connections.

3. I have been using 1/4" speaker cables since I got my first non-combo amp in 1978, and I still do, even if the gear I'm using has speakon connectors. Number of times I have accidentally come unplugged or had someone yank out a plug: 0. Most people put their amps somewhere where the audience can't get to it. And quite honestly, if someone does manage to plow into your rig, you should be way more worried about them knocking your amp to the floor than unplugging the 1/4" jack.

3. If you do the speakon conversion on new cabs, kiss your warranty goodbye.

So I can't speak for anyone else, but there is no way I'd do it. The warranty issue alone would be a non-starter for me.
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They are used cabs.
 
#48
Many places sell Neutrik connectors. One good source is parts-express.com. You can buy nice metal penn-elcom dishes that are pre punched for the connectors. This saves a lot of work.

If you ever open your speaker cabinet, note the gauge of the wire used. It isn't as heavy as you might suspect. When I build custom speakon cables, I often use rubber jacketed 18 gauge power cable from Home Depot that can be bought by the foot.

But wih shipping and parts costs, you can't beat a good pre made cable that can be found in the $20-$30 range.
 
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#49
Just opened up my Peavey TVX 410 to replace the 1/4" with a speakon to work with my new power amp. The 1/4" jack was directly soldered to a circuit board that controlled the crossover for the tweeter and adjusted the tweeter volume. So no dice. Ended up building a speakon to TS cable (had a speakon to banana plug that I didn't need and replaced the banana with a TS plug).

My point is you can't always replace the jack.
 
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#50
agedhorse said:
Iirc, back mounting takes a 7/8" hole, front mounting takes a 15/16" hole but you must measure as there are some different sizes (like an earlier version of the combo). They were supposed to follow the D series specs, but there are exceptions.

Large twist drills in thinner stick can get very messy in a hurry, and dangerous too.
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Yes, the work piece should be well clamped when drilling sheet metal.
 
#53
rufus.K said:
I's it hard to still get the 1/4" plugs where the shell is like 13/16" or so diameter?... remember those giant ones? Do they still sell them?
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Yes, but the problem with the large 1/4" plugs and the heavy cable hanging off it is that it tends to bend the plug, deform the jack bushing and become intermittent where the rivet stakes the tip on.
 
#55
agedhorse said:
Yes, but the problem with the large 1/4" plugs and the heavy cable hanging off it is that it tends to bend the plug, deform the jack bushing and become intermittent where the rivet stakes the tip on.
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As I mentioned above, I had to stick with the 1/4" jack on my cabinet because of the circuitry. Since my new amp (NAD post here) had only speakon jacks, I built a 1/4" - Speakon cable from an old banana - Speakon cable I had.

To address the drunkard falling onto the cable scenario, I used a rightangle plug. That way, it does't stick out. It's directed straight down to the floor where the cable can be effectively managed.

Nothing is foolproof, but this should help.
 
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#56
BassmanPaul said:
Agreed but with a modicum of care and slow speed it can be done safely.
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When it catches, it's helpful to have everything well clamped in a drill press.

(I have seen too many accidents of this kind, including some close calls by myself when younger).
 
#57
agedhorse said:
When it catches, it's helpful to have everything well clamped in a drill press.

(I have seen too many accidents of this kind, including some close calls by myself when younger).
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You and me both Andy! Luckily I do have a drill press in my garage. It’s like all things that one needs to do, you must have adequate tools to accomplish the task safely.
 
#58
I've step drilled, used nibblers and filed, but nothing compares to the ease of using a punch. They draw through a steel panel like butter, all it takes is a couple of turns of a wrench.

In the case of an amp, often you have to do a major disassembly to free up the space inside the chassis to properly do the work. But first carefully check that there's the clearance to accommodate a Speakon where the ¼" jack is mounted. Speaker cabs are easier to deal with.

One potential problem of doing a head. Often shorting jacks are used to offer protection to a tube amp output when a plug is not inserted and the amp is turned on. A dead short is better for a tube amp than an open circuit on the output. If a speakon is installed, you loose that safety measure.
 
#59
Note that you should draw the mandrel (male side) of the punch from the finished side through to the unfinished side so any burr does not interfere with the flush mating of the part.
 
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