# Pro Amps For Home Theater?



## pwest (Oct 8, 2006)

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?


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## khellandros66 (Jun 7, 2006)

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


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## Blaser (Aug 28, 2006)

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.


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## bobgpsr (Apr 20, 2006)

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.


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## pwest (Oct 8, 2006)

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


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## bob1029 (Feb 26, 2007)

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.


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## Josuah (Apr 26, 2006)

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.


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## bobgpsr (Apr 20, 2006)

Josuah said:


> 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 :R ). 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.


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## khellandros66 (Jun 7, 2006)

:yay:

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


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## ISLAND1000 (May 2, 2007)

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!!!


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## tonyvdb (Sep 5, 2007)

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.


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## John N (Jan 2, 2007)

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)


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## bobgpsr (Apr 20, 2006)

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


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## MakeFlat (Mar 30, 2007)

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


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## Rodny Alvarez (Apr 25, 2006)

What you guys think about this amps???












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


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## tonyvdb (Sep 5, 2007)

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.


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## Josuah (Apr 26, 2006)

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.


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## ISLAND1000 (May 2, 2007)

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.


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## khellandros66 (Jun 7, 2006)

ISLAND1000 said:


> 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.


:dontknow:

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)...

:yes:

~Bobby


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## Wayne A. Pflughaupt (Apr 13, 2006)

Rodny Alvarez said:


> What you guys think about this 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


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## ISLAND1000 (May 2, 2007)

khellandros66 said:


> :dontknow:
> 
> 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)...
> 
> ...


'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.


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## Big Worm (Mar 8, 2007)

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?


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## Mike P. (Apr 6, 2007)

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.


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## ISLAND1000 (May 2, 2007)

My opinion is it's a case of 1) marketing and 2) the only real need for the Pro amp for HT being the higher wattages required for subwoofers and 3) Pro amps usually require mods to the interconnecting cables to make em work.
But now the latest and BEST consumer subs are coming with 2500 watt amps installed such as JL Audio F113 and the Gotham or Velodyne DD series. There might not need to be pro amps in consumer HT except for us DIYers.
Actually if you read a lot of these threads, one of the most popular amps is a Pro amp, the Behringer EP2500. It is probably the DIYers most popular amp and for good reasons.
I have NEVER had the cooling fan operate on my Crown XTi 4000 while watching a movie or listening to music. I HAVE been able to make it operate by running sweeps from 10Hz-80Hz for 7-8 minutes and even then it runs on a variable speed control and shuts off in about three minutes after I reduce the volume to normal listening levels.


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## ISLAND1000 (May 2, 2007)

Mike P. said:


> 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.


I wonder if the average HT dvd movie guy :hush: would be able to hear the difference between 

.08 THD, excellent for consumer amps
vs
.5-1.0 THD average for Pro amps

at the same volumes.

I wonder if you'd even be able to HEAR the distortion difference while playing violin or piano music? :huh:


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## ISLAND1000 (May 2, 2007)

Rodny Alvarez said:


> What you guys think about this amps???
> 
> 
> View attachment 4802
> ...


Not enough POWER! 100 watts not near enough for todays HT work. Give me at least a thousand watts! . . . . I'm serious . . . .


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## Mike P. (Apr 6, 2007)

ISLAND1000 said:


> I wonder if the average HT dvd movie guy :hush: would be able to hear the difference between
> 
> .08 THD, excellent for consumer amps
> vs
> ...


Probably not. The problem arises when the amp specs state 1.0%THD and it gets tested and it's really 15% THD. Or higher. I read somewhere about amps being tested and the results, but I can't remember where. The same goes for 2500 watt sub amps. Read the specs on the JL Audio F113 and it says 2500 watts "short term". My 270 watt plate amp does 1000 watts "short term". It's all about marketing. The best part about how this hobby has progressed in recent years is how individuals have taken it upon themselves to test subwoofers and amplifiers and get real world results on the products being sold. We all benefit from it.


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## Blaser (Aug 28, 2006)

Mike P. said:


> 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.



Well what do you base this on? THD is related to output, and cannot be generalised as you made.


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## Mike P. (Apr 6, 2007)

My statement is based on the results of amplifiers that were tested and the results that were found. An example is the Buttkicker amplifier that was "great" according to people who use it for subwoofer duty and when tested it had a rediculous amount of THD.


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## Blaser (Aug 28, 2006)

Mike P. said:


> My statement is based on the results of amplifiers that were tested and the results that were found. An example is the Buttkicker amplifier that was "great" according to people who use it for subwoofer duty and when tested it had a rediculous amount of THD.


Unless I am mistaken, the Buttkicker is not a pro amp. Moreover you need to fix the output and compare between home or pro devices. And, as I understand, pro amps will deliver much higher output with less distortion.


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## bobgpsr (Apr 20, 2006)

IMO pro amps that are classic class AB amps with big heat sinks, etc for 19" rack mounting have normal low distortion specs (Crown, QSC, Behringer, Mackie, Carvin, etc). Whereas the Buttkicker amp and some subwoofer plate amps are switchers, class D, etc that may have higher distortion.


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## ISLAND1000 (May 2, 2007)

Mike P. said:


> Probably not. The problem arises when the amp specs state 1.0%THD and it gets tested and it's really 15% THD.


 You're right about that Mike although 15% THD is supposed to be around the limit of distortion that becomes audible to most people. :scratchhead:
On another forum there is the "Bink Amp Shootout" which does an excellent job of amp testing. The results of the Pro amps is really good when it comes to THD but not so good when you look at the maximum real watts VS the claimed watts for some of the lesser amps. :boxer:


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## Mike P. (Apr 6, 2007)

blaser said:


> Unless I am mistaken, the Buttkicker is not a pro amp. Moreover you need to fix the output and compare between home or pro devices. And, as I understand, pro amps will deliver much higher output with less distortion.


Yes, the Buttkicker amp is not a pro amp. I was using it as an example. My point was THD levels. For subwoofer duty you can't tell the difference between .01%, .1% or 1% or 5% THD.


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## Ilkka (Jun 8, 2006)

Mike P. said:


> My statement is based on the results of amplifiers that were tested and the results that were found. An example is the Buttkicker amplifier that was "great" according to people who use it for subwoofer duty and when tested it had a rediculous amount of THD.


You definitely shouldn't generalize the Buttkicker's high'ish THD to concern all pro amps. The ones I have seen being measured do not have any higher THD at the same output than higher priced "home amps". I think it's just another audio myth that pro amps have high THD and sound terrible.


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## Ilkka (Jun 8, 2006)

Mike P. said:


> For subwoofer duty you can't tell the difference between .01%, .1% or 1% or 5% THD.


Oh you definitely can! :yes:


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## Mike P. (Apr 6, 2007)

Ilkka said:


> Oh you definitely can! :yes:


I should rephrase that to SOME people can't tell the difference. For sub duty the Butkkicker was called "excellent" and "great". Maybe there is a pro audio 'myth'. I wonder why we don't see more pro audio amps powering full range sytems in the home. They seem to be mostly for subwoofer duty.


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## Rodny Alvarez (Apr 25, 2006)

I want to use a pro amp for my mains ( Boston Acoustics VR3), less then $300 and about 200 watts per channel @ 8ohm.

What do I need to look for ?? :dontknow: 

What do you guys think about this amps..

Thans!!

Crown® XLS 202 $299


The power amplifier shall meet or exceed the following performance
criteria: Sensitivity for full rated power at 4 ohms: 1.25 V. Rated output
with both channels driven with 0.5% THD (at 1 kHz) in Dual mode: 300
watts per channel into 4 ohms and 200 watts per channel into 8 ohms.
Rated output with 0.5% THD (at 1 kHz) in Bridge-Mono mode: 600 watts
into 8 ohms. Frequency Response at 1 watt, 22 Hz to 20 kHz: +0 dB, –1
dB. Signal to Noise Ratio below rated power (20 Hz to 20 kHz, inputs
terminated): greater than 100 dB A-weighted. Total Harmonic Distortion
at full rated power, 1 kHz: less than 0.5%. Intermodulation Distortion (60
Hz and 7 kHz at 4:1, from full rated output to –40 dB: less than 0.3%.
Damping Factor (8 ohms): greater than 200 from 10 to 400 Hz. Crosstalk
(below rated power, –75 dB at 1 kHz, –50 dB at 20 kHz. Input Impedance
(nominal): 20 kilohms balanced, 10 kilohms unbalanced. AC Line Voltages
and Frequencies Available (±10%): 120 VAC 60Hz, 100 VAC 50/60 Hz, 220
VAC 50 Hz, 230-240 VAC 50 Hz.

Cerwin Vega CV-900 $299

• 
Frequency Response: 0/-0.5dB ; 20Hz-20KHz, 0/-3dB: 5Hz-60KHz

• 
Rated Output Power (Stereo): 210 watts at 8 ohms; 320 watts at 4 ohms; 420 wats at 2 ohms

• Rated Output Power (Mono): 650 watts at 8 ohms; 845 watts at 4 ohms 
• At Full Power @4 ohms: 10.5A / 5.5A 
• Signal to Noice Ratio: 20 Hz - 20k Hz - 100dB 
• Distortion (SMPTE-IM): .05% 
• Output Circuitry: AB 
• Damping Factor (400 Hz): 200


Mackie FR 800 $299

Continuous Sine Wave Average Output Power, per channel, both channels driven, 20 Hz to 20 kHz
FR•800 FR•1400 FR•2500
2 ohms: 480 W 800 W 1400 W
4 ohms: 300 W 450 W 750 W
8 ohms: 205 W 310 W 575 W
Bridged Mono Operation, 20 Hz to 20 kHz
FR•800 FR•1400 FR•2500
4 ohms: 800 W 1400 W 2500 W
8 ohms: 560 W 900 W 1500 W
Note: Power ratings are specified at 120 VAC line voltage.
Power Bandwidth
5 Hz to 50 kHz (+0, –3 dB)
Frequency Response
25 Hz to 25 kHz (+0, –1 dB)
Distortion
THD and SMPTE IMD; 20 Hz to 20 kHz
< 0.03 % @ 8 ohms
Signal-to-Noise Ratio
> 100 dB below rated power into 4 ohms
Channel Separation
> 90 dB @ 1 kHz


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## Ilkka (Jun 8, 2006)

Mike P. said:


> I should rephrase that to SOME people can't tell the difference. For sub duty the Butkkicker was called "excellent" and "great". Maybe there is a pro audio 'myth'. I wonder why we don't see more pro audio amps powering full range sytems in the home. They seem to be mostly for subwoofer duty.


I think you are confusing some things. The Buttkicker (as all amps) doesn't have high THD at lower output levels (say below 500 W @ 4 ohm). Only when the amplifier closes up to its limits, the THD rises to several %. So unless people were overdriving/clipping their amps, there is no reason why they should have heard the distortion.


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## Blaser (Aug 28, 2006)

Mike P. said:


> I wonder why we don't see more pro audio amps powering full range sytems in the home. They seem to be mostly for subwoofer duty.


The reason is very simple and far away from the distortion issues. At home, speakers do not need great amount of power to be already very loud (human ears sensitivity). Reference Level can be reached with say a 100 W amp and 90 db speakers in many rooms.

Nevertheless, some purists (Like Ilkka:bigsmile for ex. are using pro amps to power their fronts. Don't you Ilkka?:innocent::bigsmile:

But subs are another story, they require large amounts of power.


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## Mike P. (Apr 6, 2007)

Obviously I've made some bad assumptions. Pro amps are just as good for home theater as any amplifier. THD levels are acceptable for subwoofer and full range duty. Thanks for the "education" on the subject. Now all we need is Stereophile.com to do a review on the EP2500.:bigsmile:


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## Ilkka (Jun 8, 2006)

blaser said:


> The reason is very simple and far away from the distortion issues. At home, speakers do not need great amount of power to be already very loud (human ears sensitivity). Reference Level can be reached with say a 100 W amp and 90 db speakers in many rooms.
> 
> Nevertheless, some purists (Like Ilkka:bigsmile for ex. are using pro amps to power their fronts. Don't you Ilkka?:innocent::bigsmile:
> 
> But subs are another story, they require large amounts of power.


Well not a pro amp per se but a separate power amp (Rotel).


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## Blaser (Aug 28, 2006)

Mike P. said:


> Obviously I've made some bad assumptions. Pro amps are just as good for home theater as any amplifier. THD levels are acceptable for subwoofer and full range duty. Thanks for the "education" on the subject. Now all we need is Stereophile.com to do a review on the EP2500.:bigsmile:


We are all learning! That's sure:nerd: If you want I can try a pro amp of mine with my fronts, and give you impressions...(I will have to dramatically reduce the gain, which is basically already a good thing for distortion):bigsmile:


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## Sonnie (Apr 11, 2006)

SteveCallas uses the Carvin pro amp on his VR3's in his system.

I know there are several using the Crown XLS amps. I believe we have a couple of members that use the Behringers, whether it be the A500, EP1500 or EP2500. Some use QSC... and I know I've seen some others.


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## Blaser (Aug 28, 2006)

By the way, here is a distortion figure of a pro amp that Ilkka previously provided. Still care about distortion with pro amps?:bigsmile:


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## Sonnie (Apr 11, 2006)

I don't know how to read that graph, but I'm assuming it good simply by looking at the .02380% figure.


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## Blaser (Aug 28, 2006)

Yes Sonnie, you're correct. It is a good one assuming (and I believe) all the measuring parameters involved are correct


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## Josuah (Apr 26, 2006)

You look at the primary peak and then find all the peaks that are multiples of that frequency. The first multiple at 100Hz is -95dB. The numbers in the corner seem to indicate pushing 1800W over a single 8ohm load. Which doesn't seem like something you'd normally be able to do. And I'd wonder about that a little. But that means when you're only pushing 300W over an 8ohm load, the THD should be much lower.


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## Blaser (Aug 28, 2006)

Josuah said:


> The numbers in the corner seem to indicate pushing 1800W over a single 8ohm load. Which doesn't seem like something you'd normally be able to do. And I'd wonder about that a little.


What do you mean? this is for the sake of measurements as any other amp would be measured.


> But that means when you're only pushing 300W over an 8ohm load, the THD should be much lower.


Yes, even much lower.


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## Josuah (Apr 26, 2006)

Ignore what I said about wondering.


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## bluejay (Sep 10, 2007)

> Now all we need is Stereophile.com to do a review on the EP2500.



I would love to see that. I don't know what they would say. 

I made my mind up a long time ago that I really liked reading the Stereophile reviews of cool audio gear, however, I would never be able to justify the costs involved due to my personal circumstances. As a do it yourselfer I remain content listening to "good as I can" sound. Thus a desire for more pro audio gear. :neener:


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## Sonnie (Apr 11, 2006)

A theoretical sample review clip of the EP2500 from a Stereophile reviewer: 



> Then La Capella Reial de Catalunya began singing softly and Figueras' voice began soaring over it—once again, I was immersed not just in a gorgeous performance, but in a gorgeous performance happening in that singular acoustic, and being both defined by it and glorifying it.
> 
> Then they rang the bells and I nearly fouled myself. Those immense tolls—hitting peaks about 30dB louder than the singers—just about launched me out of my almost not-so-sweet spot. The EP2500's vanishingly low noise floor may have defined the chapel, but the sheer grunt factor made that mad expostulation real.
> 
> ...


All in fun... :bigsmile:


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## bluejay (Sep 10, 2007)

You nailed it Sonnie! :jump:


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## ISLAND1000 (May 2, 2007)

Sonnie said:


> A theoretical sample review clip of the EP2500 from a Stereophile reviewer:


But really . . . . I used to get online and read these humorous threads for hours and hours . . . . now I go down to the listening level of my humble abode and crank up the Crown XTi 4000 and tune in the PEQ and create yet another frequency profile for my wonderful audio reproduction system.


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## bobgpsr (Apr 20, 2006)

^^^ You nailed it thylantyr. :clap:

Always enjoy reading your posts. :T


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