Billy Gun
Stunt Coordinator
- Joined
- Jan 22, 2001
- Messages
- 50
I was wondering if pro-audio amps could be used in a home theater setup?
What are the differences?
What are the differences?
I was wondering if pro-audio amps could be used in a home theater setup?
Why not?
THere are good pro amps, and there are ok pro amps, and then there are crappy pro amps.
Lots of pro amps are just that-amps. Not many bells or whistles to them. If you can find a decent amp spec-wise, go for it.
Oh also make sure that the inputs and outputs of the amp are compatible with your equipment(i.e.- if you don't have balanced XLS connectors, and that's all the amp has, don't buy it).
Sam
To agree with what Sam said, make sure if you choose one that it has compatible connectors. If you don't have XLR and that is all the amp has then you will not be better off. Most amps though have 1/4" inputs that accept balanced AND unbalanced so a simple RCA-1/4" cable would work.
I respectfully disagree with both of the above statements. There used to be a bit of a problem interfacing the balanced (+4 dbv ) and the consumer level (-10 dbv) components. There are several manufacturers that produce low cost interfaces. These are active units and not passive transformers; so phase shifting problems have been pretty much eliminated. Rane makes a multi input/output unit called a "Balance Buddy". They are designed to both match line level signals and impedence. Pro amps of any configuration is no longer a problem.
The problem that occurs when you use an unbalanced source at -10 dbv is that the signal is pretty much in the low end rail for signal on the pro amp. The result would be a need to increase gain either on the output of the source, or in the amp itself to get the signal to a usable level up in the linear operating range of the amp. By doing that at either the source or the amp, then you will effectivly raise the overall noise floor on your system. Even then, if you raise the gain on the output of the preamp, you may go into clipping on the output stage of the pre-amp; thereby sourcing a square wave to the amp. The amp will reproduce that and send it to your speaker. That's a bad thing.
Danny
I am powering them with an Adcom 555 two, which is 200 watts x 2, but I don't like the "Hiss" I hear during completely quiet passeges in movies.
This is exactly why the line matching IS an issue. If you have to drive the gain way up to get a respectable output you will get gate noise (hiss); whether from the source or the amp itself.
Sure amplifiers can be ordered any way you want, but how many are going to order them as opposed to getting a good (meaning cheap) deal; an overwhelming minority I'm sure.
I hear arguments constantly on these forums about small tweaks and other ways to get the best quality sound out of your system. Line level matching is a basic core fundamental in basic electronics; not to mention a common sense approach to maximizing quality audio. It is not just a tweek. A -10 dbv signal being fed to a unit designed for a +4 dbv level input WILL increase the noise floor. It can't get any more basic than that.
I have built and repaired amplifiers from many manufaturers over the years; the sound company that I had worked for was a factory service center for several different manufacturers. I have dealt with this issue hundreds of times in real world applications and it always ends up the same way.
What Tim did mention is that amps can be special ordered from manufacturers with a -10 dbv input. What is the difference? There is another gain stage introduced at the input, or the switch adds another feedback resistor to increase the output of the primary gain stage of the amp; so, apprantly line level matching is still an issue and the manufacturers are adapting their equipment to work with demand. I'm sure that the switch he referred to is to bypass the -10 dbv gain stage when a +4 dbv source is introduced.
I do believe that pro audio could be very good in a HT application; but you do have to do a bit of research on what units you are buying and be aware that there may be some "extras" required to maximize both the useable output and the S/N ratio.
The other thing that you have to ask yourself is: If it isn't an issue, then why do the amp manufacturers bother to include the added gain option on their pro grade amps?
Assuming that we all agree that Rane is an authority on audio, here is a link to the Balance Buddy.
Balance Buddy
They apparantly think that it is a big enough issue to manufacture the device soly for this particular application. There are other links to papers written on the subject that I will add later, right now I'm at the office and I don't have time to list them.
Danny
The jist of the matter is that 99% of the consumer equipment outputs more than enough signal for 99% of the pro amps...
And this has been my point from the early days.
This balancing issue and -10 vs +4 issue alludes to the concept that preamp units are supplying -10db fixed output, which is not the case. I haven't gottent oo far into dedicated PRE/PRO units, but every receiver with a line Sub out I've played with has been MORE than able to pass the right amount of voltage to get a pro amp hopping.
Even Crown stuff, which I think uses 1.4v input sens, I've been able to get to clip with my Denon at +3 sub 00 vol and playing test tones.
So Denon provides enough voltage from the sub out, I would imagine that most dedicated preamp units would provide plenty of juice without running them wide open.
I think Gregg Loewen runs an Outlaw Pre/Pro with QSC DCA amplifiers- and although I don't know the fixed Input Sens on the DCA, I think he gets ref level at -25 on his master volume knob without boosting any of the channels beyond one or two clicks (heck the sub level is reduced a few clicks)...
-Vince