Pro Amps For Home Theater?

**pwest** · **10-28-07, 12:10 PM**

What are the pros and cons of using pro amps for home theater and music? I have a 7.1 yamaha receiver rated at 140 per channel. The speakers are JBL S series rated 150-175 watts,89-91 db syns. The room is 17.5x14.5 with a 68" opening on one side. Most of my music listening is in 7 channel stereo. This is ok with jazz, blues, and alternative, but it cannot hang with AC/DC. What do you think?

**khellandros66** · **10-28-07, 05:43 PM**

Pro amps are usually spec'd better and more reliably. I'd take a Crown XTi over a $1500+ 2ch Hi-Fi amp, just cause I know its crisp and with the built in EQ (software included, PC with soundcard and RTA mic needed for measurements) Its tough to beat.

Drawbacks are they do often have a fan in them cause they need to assume you are using an array of amps to power an array of speakers in a live stage/dj eviroment.

Rueben (SandmanX) I think uses 4 Crown XTi 1000 and a 4000 for LFE

~Bobby

**Blaser** · **10-28-07, 05:53 PM**

Pro amps are the way to go IMO. Cheaper power, and anyway I wouldn't care about amps distortion as they will always be much less than the speakers...and can be neglectable if (of course) we stay within the amp limits.
As bobby said, the drawback is the fan (or fans), but once you play any stuff (even at moderate level), you can't hear it anymore.

**bobgpsr** · **10-28-07, 06:07 PM**

And quite a few of those of use who use a pro amp for home theater (especially for driving DIY subwoofers) modify the fan's electrical drive. Take the covers off and insert a in-series dropping resistor of just the right ohm-mage and wattage to still let the fan turn but be much quieter. The value for this resistor will vary according to the fan voltage and current draw.

I also included a switch to bypass the dropping resistor when I know I'm going to be pushing the amp.

**pwest** · **10-28-07, 06:18 PM**

Thanks for the responces, I have bought a yamaha pc1002 that can be bridged for 300 watts for the ceter and a yamaha p2201 that is 230x2 and a 44 space rack for my gear. I have not hooked these up yet because I wanted to get the other 2 amps and get them all situated in the rack first, but I figured that it might be a good idea to ask some questions before going any farther. If there will be any problems with running these through the pre-outs on the receiver I thought I should know up front. Thanks again, Phil

**bob1029** · **10-28-07, 11:20 PM**

I love using ep2500 to run my mains. The only downside is that it can get very warm and if the fan isnt modded, it is loud. Otherwise, more transient response than I could ever use and unrelenting continous power. To compare it to the power of a 140w rms reciever is like apples/oranges.

**Josuah** · **10-29-07, 11:35 PM**

You don't necessarily need to introduce a resistor to reduce the fan speed, and in fact that might not be good because you're decreasing the air flow as Bob described. Another solution is to replace the cheap fan with a high quality fan made for quiet computers. You can get the same amount of air blowing through (compare the ratings) but with much less noise.

**bobgpsr** · **10-30-07, 07:52 AM**

Quote:

Josuah wrote:

You don't necessarily need to introduce a resistor to reduce the fan speed, and in fact that might not be good because you're decreasing the air flow as Bob described. Another solution is to replace the cheap fan with a high quality fan made for quiet computers. You can get the same amount of air blowing through (compare the ratings) but with much less noise.

I monitor the exhaust air temp coming out of the side vents on the Mackie pro amp (using a scientific instrument -- my fingers

). Normally fairly cool -- but when I am pushing the amp with a longer high bass level session (which is loud), air starts to feel warmer -- so I flip the bypass dropping resistor switch. I looked up quieter fans that have the right voltage and size, so I know of a fan model that is rated a few dBA quieter -- but first I thought I'd try the dropping resistor mod and see how it worked. I'm happy with the results after 18 months of use.

**khellandros66** · **10-30-07, 09:01 PM**

You can use Scythe pc fans they are whisper quiet and move good air. That owul be my solution. Or setup a well ventilated rack with a door. Have cool air come in from the front bottom using 2x120mm scythe fans and have hot air pushed out the back top with 2x120mm scythe fans. Easy wall to setup these is go to radioshack and grab a couple AC to DC power adaptors (like the ones for cell phones chargers etc) grab ones that are like 5-10v, and 1amp cut the end off and solder the red/black wires to the fan cables (ignor yellow its for speed control in a pc) then you can plug em in to a powerstrip or an aux outlet on a receiver, so they only run when the rest of the equipment is.

~Bobby

**ISLAND1000** · **10-31-07, 12:56 AM**

I use a Crown XTi 4000 to drive my sub but it's so versatile and pleasant to listen to I might get 4 more to power each speaker. The parametric equalizer is amazing and it's all controllable through a hook-up to your laptop or desktop computer. Amazing for the price and 1200 watts per channel unbridged!!!

**tonyvdb** · **10-31-07, 08:02 AM**

I have a Samson servo 4120 4 channel amp and will not ever go back to using the on board amplification of the receiver. Its cleaner and offers more power. Bang for buck its the way to go.
The only issues is that some "pro" amps can have a slightly higher noise floor but in most cases this is simply not noticeable and they rarely have remote power on off so you need to turn it on/off by hand.

**John N** · **10-31-07, 09:37 AM**

All amps are not created equel . I'd pick a good pro amp over a cheap home amp and a good home amp over a cheap pro amp. (This debate always turns into pro vs. home, watts vs. watts...)

I'd like to try my QSC plx 1602 on my mains some day . (using a Parasound 1500a right now)

**bobgpsr** · **10-31-07, 12:44 PM**

Agreed that QSC is a quality brand. Better than my Mackie's IMHO.

**MakeFlat** · **11-01-07, 12:15 AM**

If anyone is looking for quiet pro-amps, try Yorkville. They even have air filters. Now I call that good engineering.

**Rodny Alvarez** · **11-01-07, 07:52 AM**

What you guys think about this amps???

VLP-STACK.jpg

http://www.americanaudio.us/product....=1276&cat=Amps

**tonyvdb** · **11-01-07, 03:43 PM**

I dont see a problem with American audio reading the specs, but they can sometimes be misleading so you really dont know until you try them.

**Josuah** · **11-01-07, 04:18 PM**

Also, lots of people claim QSC or Crown or whatever to be much better than Behringer, but I think that may only apply towards durability and reliability, rather than performance. I haven't actually seen anyone claim measured differences. If you're not sticking it into a gig rack, I'm not sure it's worth it to go with the more expensive brands.

**ISLAND1000** · **11-01-07, 04:38 PM**

The Crown XTi series amps contain a Parametric Equalizer in addition to the high quality high power amp and has a hook-up which can operate the controls on both the amp and PEQ via computer or laptop.

**khellandros66** · **11-01-07, 06:06 PM**

Quote:

ISLAND1000 wrote:

The Crown XTi series amps contain a Parametric Equalizer in addition to the high quality high power amp and has a hook-up which can operate the controls on both the amp and PEQ via computer or laptop.

So what are you saying this a really good amp that makes the home theater more balanced and cool, not to mention assisting in better timbre matching from 100Hz-20kHz (most import range in timbre matching imo)...

~Bobby

**Wayne A. Pflughaupt** · **11-02-07, 05:31 PM**

Quote:

Rodny Alvarez wrote:

What you guys think about this amps???

http://www.americanaudio.us/product....=1276&cat=Amps

Where to begin? The 0.1% THD spec is pretty high for modern electronics (although probably still low enough to be inaudible). Using the EIA power rating standard (@1 kHz) instead of the more stringent FTC standard means that broadband power (i.e. 20 Hz – 20 kHz) could be up to 20% less.

And glaring typos in the manual? Hope their attention to detail on the assembly line is better...

The absolute lack of a S/N ratio (noise floor @ idle) spec would be a deal breaker, as far as I’m concerned. Unless it was going to be used for subwoofers

Regards,
Wayne

**ISLAND1000** · **11-03-07, 09:12 AM**

Quote:

khellandros66 wrote:

So what are you saying this a really good amp that makes the home theater more balanced and cool, not to mention assisting in better timbre matching from 100Hz-20kHz (most import range in timbre matching imo)...

~Bobby

'YES' I consider the Crown XTi to be a really good amp and not only good at timbre matching from 100Hz-20KHz but also as a sub amp.
You can use one channel for sub amp duty and the second channel for the rest if you're into pro sound stuff.
So far, I've had mine 4 month's, I've used the amp mainly for HT sub duty. I use three of the six PEQs to adjust the 10Hz-100Hz range to acheive a fairly flat in-room response.
Adjusting the EQ using a laptop computer is as good as it gets.

**Big Worm** · **11-03-07, 10:44 AM**

Here is my question that I always wondered.

If pro amps are good for home theater, why do you not see more people running them? Is it because of the fan noise?

**Mike P.** · **11-03-07, 11:03 AM**

Most pro audio amps that are used in HT are used for subwoofer duty where the pro amps higher THD doesn't matter that much.

Advertisement