[Rant] Minor Rant III: For a Few Hollers More

It was probably 200W peak, which means it was more like 50W continuous. You want your amp to be at least as powerful as the continuous (RMS) rating of all your speakers combined, or when you have your volume turned up all the way, you'll burn out your amp and probably blow your speakers too.

Also, Pro (indoor) AV is a little different from Car audio, in that most cars don't have digital signal processors with peak limiting compressors to protect the speakers from too much juice from the amps, whereas we always do in our installations.
This was the home stereo setup with the big SB-G400 speakers. Input power rated at 200W, and I don't have any specs for power beyond that. Connected to that 70W receiver, you're looking at a hospital stay at anything past half volume.
 

GasBandit

Staff member
This was the home stereo setup with the big SB-G400 speakers. Input power rated at 200W, and I don't have any specs for power beyond that. Connected to that 70W receiver, you're looking at a hospital stay at anything past half volume.
Speaker manufacturers are notorious liars. Especially resi and automotive, where nobody's actually getting out voltmeters and doing the math. It's even worse than hard drive manufacturers who want to pretend that 1000000 bytes is a meg. Most of them advertise their "peak" rating as their watts, when what really matters is the Root Mean Square (RMS), or "continuous" rating.

Take, for example, those ElectroVoice 1122d speakers from my example. This is a really kickass pro-grade speaker. You can deafen an entire cafeteria full of rowdy middle schoolers into submission with 2 of these, easy, being driven by the appropriate amp.

Their peak wattage is 2400 watts. The RMS? 600 watts. So, the amp paired with them needs to be about 600w per channel. Often we go with the QSC CX-Q 2k4, which will get you about 700w per channel at 8 ohms (which is the impedence of these particular speakers), but man is it expensive. For this job, I went with a Dynacord L2800FD for about a third the price for the same wattage. Our DSP will have a peak limiter in its signal processing chain to make sure that too much power never reaches the amp for the speakers to get overdriven.

Numbnuts thought a Crestron AMP-X300 (at 150 watts per channel for almost the same cost as the Dynacord) would be enough, pushing through 18 gauge wire (which is fine if your speakers are only 20 feet away from your amp... these are not).
 
This seems weird from a guitar point of view. I have a 30W tube amp and 120W of speaker. I would rather not burn out my speakers with too much power, I also am not a fan of speaker breakup as I the next step is usually come seperation.
 

GasBandit

Staff member
This seems weird from a guitar point of view. I have a 30W tube amp and 120W of speaker. I would rather not burn out my speakers with too much power, I also am not a fan of speaker breakup as I the next step is usually come seperation.
You can burn out speakers with too LITTLE amp too... if you turn your amp up all the way and it doesn't generate enough power to maintain the sine wave pattern, it will clip, holding the speaker coils in position at the peaks instead of letting them oscillate freely. That utterly kills speakers (and burns out amps).

And again - the people who putt watts on the boxes of speakers are also bigger liars than used car salesmen. If your speaker is 120W "peak," it could very well be 30w RMS.

And if you don't believe me, here's corroboration from CNET:


Many speakers have a "maximum wattage rating" on the back. Treat this as a "minimum wattage rating." You are far more likely to damage a speaker giving it too few watts and trying to play it too loud. High-end amplifier companies make amps with more than 1,000 watts, and you could plug in a $50 speaker into it with no problem. Though why you'd want to...
 
There is that, if you are talking solid-state. But in the tube amp world my 30W amp is rated before breakup, guitar players rule of thumb is to double the rating at least for full overdrive(breakup) and then buy speakers. I already blew a set of 20W speakers in my youth. The sag from the tube rectifier doesn't allow the amp to always be peaking.

Guitar speakers are sold at RMS not peak, I didnt realize that audio/pa speakers were sold differently.

I know a lot of guitar players will pair 2 30W speakers with a 100W amp in order to overdrive the speakers, but I am not a fan of speaker breakup. I prefer my breakup in the tubes.
 
Last edited:

GasBandit

Staff member
There is that, if you are talking solid-state. But in the tube amp world my 30W amp is rated before breakup
I have to admit I don't know much about the difference between tube amps and solid state, as all the amps we sell are solid state.

But at least as far as that goes, I've done setups as small as a four-person conference room and as large as a collegiate baseball stadium, using the methodry I have described.
 
I have to admit I don't know much about the difference between tube amps and solid state, as all the amps we sell are solid state.
Maintenance aside, solid-state amps have much lower latency and so can reproduce transients better. But that is not always a good thing if there is no limiter in the chain to keep it from shredding your cones/diaphragms/ribbons/whatever.

--Patrick
 
I have to admit I don't know much about the difference between tube amps and solid state, as all the amps we sell are solid state.
I can't see tube amps ever becoming relevant again in the PA realm. Sourcing tubes for my amp is a pain. I can't imagine the size of an amp for that wattage in tubes.
 

GasBandit

Staff member
I ran the carvin audio thing past some colleagues, and they agreed that amp power being a 1/4 RMS of the speakers is generally safe if it is your own system and you know its volume limits. But it would be a bad idea in a public system (like, say, a classroom) because there's always gonna be that one guy who comes along when you aren't there and keeps turning it up because "not loud enough" and next thing you know you are clipping like crazy because your amp can't push enough power, everything cooks til it breaks, and sounds like shit during and after.

It would definitely not be good in the music classroom setup we were working on, which is really emphasizing sound quality and volume.
 
The upside of working at a school, but being a District-level employee is that the Principal at my school is not my direct supervisor. Definitely a good thing at the school I am at.

The downside is that the day before holidays, they tend to let all the teachers and staff go home early and I have to stay on until the regular end of the day.
 

Dave

Staff member
Took Poppy to the dog park today. She’s known very few humans and only like 2 or 3 other dogs. And she’s scared of EVERYTHING.

At first she was a little nervous. She stuck by my side and shied away from any attention. But a couple people came by and petted her. A couple dogs ventured over and she took a few steps away from me.

Then Fucky McFuckface brought in his two aggressive dogs and it all went to shit. They ran up on all the dogs hackles raised, chest bumping and growling. Including 4 month old Poppy. The owners apologized but it sounded like it was just something they thought they should say since they didn’t do anything about it. When we left one of the dogs was getting into a fight with the sweetest old German Shepherd we’d been playing with.

Poppy is probably scarred and won’t want to go back. She whined all the way home.
 
I hate our trash company.
View attachment 37518

They have torn up every single trash and recycling can I have. I don't mind so much the recycling can, because they supplied it. But I bought these damn trash cans for $54 each at home depot.
Is this a lift arm type pickup or pulling the bags out of the can thing? If it’s lift arm, you have to supply your own cans? We have a lift arm type truck here, but the company (city) supplies the cans for curbside, and repairs/replaces damaged cans.
 
Is this a lift arm type pickup or pulling the bags out of the can thing? If it’s lift arm, you have to supply your own cans? We have a lift arm type truck here, but the company (city) supplies the cans for curbside, and repairs/replaces damaged cans.
They do it manually. We're supposed to bag everything, and I do. But they're strong (said in a Major Payne voice) and usually just lift the whole can up and dump it, and then just throw it down, I guess just about as hard as they can.

They've somehow cracked my recycling bin, last week, and that's done with a lift arm (and they supply the bin). That said, I've seen them dump that manually, too, when they're in a rush and don't want to add the few seconds per can of the slow hydraulic arm.
 
They do it manually. We're supposed to bag everything, and I do. But they're strong (said in a Major Payne voice) and usually just lift the whole can up and dump it, and then just throw it down, I guess just about as hard as they can.

They've somehow cracked my recycling bin, last week, and that's done with a lift arm (and they supply the bin). That said, I've seen them dump that manually, too, when they're in a rush and don't want to add the few seconds per can of the slow hydraulic arm.
Dang, sounds like needing to catch some video to send to the company to point out the disregard to your property and the companies property.
 
Oh, I've had words with this guy before :) Last spring, I got a weed violation, because I had 4 or 5 weeds spring up right after a spring rain. So I had him go through the section of lawn that said anything about weeds. It says "predominately grass" in the HOA guidelines...meaning my yard can be a quarter weeds, and still be "predominately grass" and that the violation's spirit was for people not keeping up their lawns--not for people who had a couple weeds spring up right after a rain.

He backed down.

Edit: on a positive note, he did send out a letter to the whole HOA afterwards saying he was going to be providing better guidance to the company they contracted to do inspections concerning the weed violations
 
Last edited:
Top