Thanks - much appreciated ... it was your videos that showed me to get the monitors and tube mics, makes a *huge* difference in production value ... I appreciate the tips as always...


take care,

ken

I've got a new pair of Alesis M1 Active Mk2 monitors, they're great - but is it ok to leave them powered on 24/7, or not?

I don't know, mine have only been on continuously for five years so far.

:O)

And if you don't have your monitors on Auralex Mopads, you're in for a very nice surprise when you do get them (it's foolish not to, considering the huge improvement in sound for very little money).

Vacuum tubes are really incandescent "light bulbs," with a filament that has a limited life.

Hey now that's another fine tip, thanks! I'm ordering from zzounds as we speak..
http://www.zzounds.com/item--AURMOPAD

I really appreciate all these tips; let me know if I can return the favor, w/tips on how to make a fortune selling dvds online etc... Those pads are a great idea to isolate from the tabletop. Good to know re 5 years and still on! So many things I wish I'd known about years ago... it's great to get these tips from you guys, means a lot. Thanks!

Ken

My M-Audio, 5.1 set up only made it about 3 months. The front satellites took a dump, but the woofer still works. I hope it 's an easy fix, but very disappointing it happened this quick. I never hooked the center and rear speakers up yet.

I hate to be the green party popper here...but..
unless they have low-power standby modes, then that's a lot of energy just being wasted for convenience / laziness

A-they do have low power modes (I think most of the powered monitors do)
B-Monitors, like lightbulbs, tend to go when being turned on or off.

Type A amplifiers also tend to draw more power the louder the signal is. So, if you're not piping signal through them at night then they won't draw much.

As far as the original question goes, i always apply the fingertip test. If the device is too hot to comfortably touch then it should probably be turned off when not used for long periods. If you can leave your hand on it comfortably then it should be fine. Another thing to look for is devices that keep getting hotter the longer they're on after the initial warmup period. That indicates a serious design flaw and you might want to consider a different piece of equipment.

Well, these monitors don't have Class A amplifiers, and I dare say no active monitors do.

"Class A" refers to running the output transistors with such a high bias current that the current through the output stage never goes through a zero transition. This makes for wonderful sound, and also creates a phenomenal heat source from the "wasted" power.

Class B has no current going through the output transistors at rest (in the absence of signal), and are subject to crossover distortion when the output signal goes through the zero transition. Quite power efficient though.

Class C is not used for audio to my knowledge, as it generates enormous distortion due to use of negative bias on the output stage. Works great for frequency modulated RF power amplifiers though, as all the nastiness can be easily removed from a relatively narrow signal (bandwidth wise).

Class D is switching amplifiers, popular for hearing aids and other battery powered equipment. Why? It has by far the highest efficiency of all amplifier designs.

So which class is used for active monitors?

If you answered "none of the above" or "umm, a combination" you'd be right on.

Class AB is a good compromise, where you run anything from a few milliamps to much more through the output stage at rest, but not enough to prevent the output stage from going through zero when "cranked to 11." Basically the stage runs in Class A for less intense passages, which is where our ears are the most sensitive anyway.

By setting the bias current low, you get low power consumption, little heat, and better sound than a pure Class B.

It's not really the current that matters though, it's the voltage. If the input resistance of the transistor is relatively high, and most are, then the voltage needed for pure class A will draw very little current.

It gets worse if you run a surround setup. I have a 5.1 (I reduced from 7.1) setup. With the sub having a nice extra-large power amp. Factor that in, along with 5x 100W+ power consumption, over time - that's a lot of juice, which in terms of money saved could be spent on more toys. Just worth considering. Now leaving Behringer gear on 24/7 - that's a REAL sin! hehehe

Hi,

I don't think this is the right forum for power amplifier topology discussions. However, Chienworks please do not spread false information. The input resistance of the output transistors has nothing to do with the amp's idle power consumption. Class A is always wasting lots of power, both at idle and full output power. Most smaller class AB amplifiers (used in active montors) consume something like 4..10W idle power per channel. This is wasted power indepent of how you calculate it. If you need it to warm your house - there are better ways of doing it.

A transistor power amplifier degrades mainly due to repeated extreme temperature cycling. Electrolytic capacitors also "wear out" due to high temperature and simultaneous voltage bias.

It is completely fine to leave the monitors constantly on if you prefer it, but why should you? I have opted for a solution with a power strip with a built in switch, when I'm done for the day I switch off everything to save power, and also for the sake of overall safety. You will not wear out your active monitors by turning them on and off repeatedly something like once a day. Theoretically they would even last a little bit longer this way.

Christian

Christian is right, an easily accessible power strip switch is a good idea.

What I really would like is a remote switch for a power strip that could control equipment that may be turned off at night. I don't want to pull out the power strip itself to turn things on or off.

I have a UPS and half a dozen power strips under my workstation, some of them feeding equipment that must stay on. The rest of course really should be turned off, and I'm glad Christian reminded me of this.

You sometimes see "current amps" as a term for home electronics with a particularly low impedance output, but common power amps are voltage amps.

Class A requires that the output stage produce full power at all times, with that power going either to heat your studio or to move the voice coils of your speakers.

I used to have a beefy Class AB studio amp that was Class A up to 750W and class B from that up to 2,000W output. Needless to say, this was great in winter and not so great in summer... It sure sounded sweet though.

Perhaps something like this would be of interest?
http://www.maplin.co.uk/Module.aspx?ModuleNo=217801&doy=12m3&C=SO&U=strat15

http://www.oneclickpower.co.uk/images/oneclickdemo.swf

The voltage isn't held at a constant 70 volts. Here's a decent explanation:

http://www.alectrosystems.com/audio/Distribution/70volt.htm

Thanks John for that correction. Now I understand also why so many of these systems sound so crappy (cheap transformers).

The Maplin auto power strip sounds like a great possibility for home theater, anyone seen these in the U.S?

They wouldn't work for my computer hookup though, as I do automatic offsite backups every night (EMC MozyPro, I pay $14.95 for 22GB).

Unless I could turn off something else and use that to turn off the power strip for the monitors, etc.