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Posted By: Zimm Added an Amp...WOW, kinda. - 04/25/09 12:26 AM
OK, FredK and JohnK (and many others) have taught me much in the last months about amps. My opinion has changed dramatically, and my opinion yesterday was that it only really matters at the edge of the amps power limits, where dynamic peaks go beyond the amps clean power range.

Turns out, i was right; and so were John and Fred. Today I decided to stop pestering the educated folks laughing at my Krell/Bryston/McIntosh erection and go get a damn amp. So, because I am cheap, I went to Guitar Center and found a Crown XLS 402 stereo amp for $350. The musician I found there said Crown is the live standard bearer while other were more recent entrants to the field, so I figured that was safe for a purchase I expect to return in a few days. My speakers are 4 ohm, so it makes about 450 watts per channel. My AVR is a 2001 Denon AVR 3300, that I love, and is rated at 110 wpc. But test reports say it starts to clip the signal at about 80, and hits 1% distortion at 180w into my 4 ohm speakers. Again, i love the sound of this amp, and I like it loud.

So I hook up the Crown and skip the six week burn-in. I heard that is BS! Final verdict - it is better, noticeably better. Here's why: Peaks are dead clear. I thought my speakers added some harshness at the edge of male voices and the peak of guitar and other string solos. Not so, it turns out. My AVR adds distortion, at high levels, to mail voices and high guitar notes. That's the long and short of it - my AVR was outside its clean zone more than I ever imagined.

Also, music has more peaks that I knew. Listening to Dave Matthews at RCMH (Blu Ray in 2ch PCM), I used a meter to see if it was just the volume making it sound "better" [quick answer: yes it is] and noticed that on the first track, Bartender, the SPL meter went from 92-94 constant, to peaks of 101-105 - CLEANLY. On Dire Straits "Ride Across the River" it bounced off 109 [yes that level is F'n loud] but it never distorted. On my Denon, the dynamic range was much more limited - between 92 and 100 on DMB. And since the amps don't add anything to the music, I know that was in the recording, but my Denon just could not get there.

As I said, it is the volume that matters. What I did not realize is that the "volume" is a second by second issue. I was thinking loud day versus quite day, but turns out the volume is much more dynamic than I knew and those peaks really add something.

To keep this rather short (for me) I'll say this: the amp makes little or no difference (as Fred and John say) for most listening. Sitting here with DMB at nice soft levels (80 to 85 db) it makes no difference that I can hear. (Actually, I perceive some mild changes, but I think they are psychosimatic).

But if you like it louder, or have a bigger room, the extra power is immediately evident. With 400+ watts flowing (never clipping the amp) the guitar plucks, the DMB wails, the Knopfler picks (all without a sub turned on) you get clean sounds at the edge of you old amps ability. You get the clean sound of 85db but at realistic levels. You won't notice it every day, but for critical listening, you will appreciate the difference because the music has more dynamics than I ever knew. I keep turning it up. DMB on piano, turn it up more. Tim Reynolds on guitar, make it real. I'm hooked.

So everybody was right. But man, even my wife was impressed with Dire Straits at levels she would never listened to just my AVR. For $350, I'm having trouble figuring out why to return this amp. The fans or loud, but apparently that is a problem across the pro amp realm so I might just have to adjust. The real issues is THD (as warned). I notice in quite parts more background hiss than I am used to. This amp has <.5% THD, and I know that should not matter, but Alan's reference to .2% is leading me to think I am hearin that .3 difference. Could be the AVR (now 2ch pre-amp).

Uh oh, might be the signal wires! \:o I'm using some non-levitating copper wire. I bet that is the hiss.

I can't freaken imagine what the Axiom A-1400-8 sounds like with about 3 times this much power on tap for 8 channels without the THD issue. And now I see the value of that amp. I would need 4 of these A/B amps to equal half the power of the Axiom, while the Axiom is the size of one of these Crown amps and skips the hiss. Nice job Axiom.

Three year warranty for whatever that is worth. Thanks all.
Posted By: SirQuack Re: Added an Amp...WOW, kinda. - 04/25/09 12:34 AM
Nice review Zimm, I'm glad your happy, as am I with my Odyssey monoblocks, that is even better than a stereo amp. \:\)
Posted By: fredk Re: Added an Amp...WOW, kinda. - 04/25/09 12:47 AM
Nice post Zimm. Thanks.
Posted By: tomtuttle Re: Added an Amp...WOW, kinda. - 04/25/09 01:20 AM
You're wrong, I tell you! Delusional!
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/25/09 02:01 AM
 Originally Posted By: sirquack
I'm glad your happy,

Oh, I love upsetting the spell-check police. Your email shows your intent desire to maintain your forum.

If I return the Crown, I think I might go the Odyssey route - they are clearly the best deal I have seen, with Emotiva close behind. But even there, getting to 400 watts per ch gets expensive. I think there are some pro amps that get below .2% and I may try to get one of those. But for $350 (plus $20 in balanced-t-RCA plugs) this is pretty impressive. I looked inside, and this thing has a huge toroidal transformer, but there are many competitors in the sub-$500 class. So why can't Emotiva or Odyssey make a 500 watt (4 ohm) amp with RCA inputs?
I still don't get that. Economics is a part of my daily life and supply and demand should have exploited this issue long ago. Maybe THD is a real impediment to massive power.
There must be something to explain why Crown, QSC, Mackie, Yamaha, and other don't offer a HT version with RCA plugs for half the price of Rotel, et al.
Posted By: LT61 Re: Added an Amp...WOW, kinda. - 04/25/09 02:49 AM
Nice post.

IMO, THD is one of the most important numbers to consider when buying an audio/AV amp.
For some reason, (which I can't recall just now) most A/V amps have high THD numbers until you get into fairly expensive (relative) equipment. I don't care what anyone tells you......you will hear 1% THD.
Posted By: pmbuko Re: Added an Amp...WOW, kinda. - 04/25/09 04:09 AM
LT61, even inexpensive amps have low (< 0.1%) THD now.
Posted By: JohnK Re: Added an Amp...WOW, kinda. - 04/25/09 04:15 AM
Very good, Charles; enjoy. I do have to comment about one statement however: 80-85dB is by no means a "soft" level, it's quite loud and is the upper limit for long term exposure without hearing damage. For example, ordinary conversation with a nearby person would typically be about 60-65dB(doesn't always apply to wives)and 20dB above that is quite a significant jump considering that a 10dB increase is said to be subjectively "twice as loud".
Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/25/09 05:32 AM
Nice post Zimm.

I agree with the fact that the amp plays better loud, but I think at most volume levels, not just high.

I tested my amp with an SPL meteras well and from 75db and up it made a very significant difference. I can listen at lower db levels now and get the same sound I would get only at higher volumes. The speakers just come alive sooner \:D
Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/25/09 06:20 AM
That was with M60's though(8ohm) so we might just get different results.

I couldn't edit the above post.
Posted By: JohnK Re: Added an Amp...WOW, kinda. - 04/25/09 06:48 AM
Misti, amplifiers simply don't work that way; they have no capability of performing a miracle by making speakers "come alive sooner" at lower volume level. Volume is volume.
Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/25/09 07:01 AM
What I meant is that at the same SPL as before, the speakers have better bass, mids and there is more detail everywhere. Before I had to listen at higher SPL for the speakers to have this "sound". Maybe I have crappy receiver, good thing it has pre-outs.
Posted By: jakewash Re: Added an Amp...WOW, kinda. - 04/25/09 09:15 AM
Zimm might I send you to Outlaw Audio and try out the M2200

http://www.outlawaudio.com/products/2200.html
Posted By: Spoiler Re: Added an Amp...WOW, kinda. - 04/25/09 12:50 PM
I like mine, and they're dead quiet... and on sale!

The Behringer Europower amps seem worth a look. Low distortion, good price. They have fairly noisy fans, but there are sites for DIY's to quiet them down.

Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/25/09 01:51 PM
 Originally Posted By: jakewash
Zimm might I send you to Outlaw Audio and try out the M2200

http://www.outlawaudio.com/products/2200.html


Thanks, i had not found those. For $270 per ch that is pretty good. Still not the power level of this Crown (450/ch at 4 ohms) but clearly a bargain with low THD. it is now on the radar!
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/25/09 01:59 PM
 Originally Posted By: JohnK
Misti, amplifiers simply don't work that way; they have no capability of performing a miracle by making speakers "come alive sooner" at lower volume level. Volume is volume.


I accept that the impact is driven by a placebo effect, but I do "find" more bass even at low levels (this time about 70db). They call it weight I think. The only non-placebo explanation I can offer is possibly power reserves allowing bass (without a sub) that a smaller power supply can't reach. Sames as the greater dynamic range I explained above. But that is far from scientific, and I'm too lazy to do true A/B testing for the group.

That is the most surprising aspect of the external amp issue for me. There literally was more music than I was getting - 2 to 3 db of sound peaks. I didn't expect that and i think it adds something to the experience, when you exceed my old amps comfort zone of 80 to 100 watts.

And just to show I am not completely cured, I could swear the image moved higher in the room. No idea why, but Knopfler's voice is about 18" higher on "You and Your Friends" than I recall on the Denon. Damn powerful placebo!
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/25/09 02:27 PM
 Originally Posted By: JohnK
Very good, Charles; enjoy. I do have to comment about one statement however: 80-85dB is by no means a "soft" level, it's quite loud and is the upper limit for long term exposure without hearing damage. For example, ordinary conversation with a nearby person would typically be about 60-65dB(doesn't always apply to wives)and 20dB above that is quite a significant jump considering that a 10dB increase is said to be subjectively "twice as loud".


And that is where I think so much of the debate on the amp issues lies. To me, 85db is nice. No, it is not soft, but it is far from the live instrument volume you are trying to reproduce. If 85db is near your top end, then a 5000 watt amp would make no difference. But trying to recreate a live emotion (not live rock concert! ), where 100db is often found, and 105 is common, then these more powerful amps just keep the signal clean so you don't get the distortion of my Denon clipping the signal.

In short, I agree with you, and your wrong. ;\)
Posted By: bugbitten Re: Added an Amp...WOW, kinda. - 04/25/09 02:29 PM
 Originally Posted By: Zimm
 Originally Posted By: JohnK
Misti, amplifiers simply don't work that way; they have no capability of performing a miracle by making speakers "come alive sooner" at lower volume level. Volume is volume.


I accept that the impact is driven by a placebo effect, but I do "find" more bass even at low levels (this time about 70db). They call it weight I think. The only non-placebo explanation I can offer is possibly power reserves allowing bass (without a sub) that a smaller power supply can't reach. Sames as the greater dynamic range I explained above. But that is far from scientific, and I'm too lazy to do true A/B testing for the group.

That is the most surprising aspect of the external amp issue for me. There literally was more music than I was getting - 2 to 3 db of sound peaks. I didn't expect that and i think it adds something to the experience, when you exceed my old amps comfort zone of 80 to 100 watts.


I must be taking the same placebo.

I'm with Zimm on this one.
Posted By: jakewash Re: Added an Amp...WOW, kinda. - 04/25/09 05:00 PM
After my A1400 experience I can't buy a seperate amp soon enough.
Posted By: MarkSJohnson Re: Added an Amp...WOW, kinda. - 04/25/09 06:12 PM
Damn, you guys make me want to order a couple of those Outlaws. I've been saving their Sale e-mail as a reminder.
Posted By: PeterChenoweth Re: Added an Amp...WOW, kinda. - 04/25/09 06:37 PM
Cool Zimm. \:\)

Thanks for sharing.

Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/25/09 06:41 PM
Get a couple and see for yourself, if they have a 30 day trial that is. \:D Great price too.

I purchased the amp with the full intent of returning it if it did not make a difference. It stayed.
Posted By: Ken.C Re: Added an Amp...WOW, kinda. - 04/25/09 07:50 PM
Anyone have those M2200s floating around? How hot do they get?

I've been scared off by the amp manuals suggesting you have a separate 15A circuit for them, yadda yadda, tons of clearance, yadda yadda, since I don't have much of either.
Posted By: RickF Re: Added an Amp...WOW, kinda. - 04/25/09 07:55 PM
 Originally Posted By: bugbitten
 Originally Posted By: Zimm
 Originally Posted By: JohnK
Misti, amplifiers simply don't work that way; they have no capability of performing a miracle by making speakers "come alive sooner" at lower volume level. Volume is volume.


I accept that the impact is driven by a placebo effect, but I do "find" more bass even at low levels (this time about 70db). They call it weight I think. The only non-placebo explanation I can offer is possibly power reserves allowing bass (without a sub) that a smaller power supply can't reach. Sames as the greater dynamic range I explained above. But that is far from scientific, and I'm too lazy to do true A/B testing for the group.

That is the most surprising aspect of the external amp issue for me. There literally was more music than I was getting - 2 to 3 db of sound peaks. I didn't expect that and i think it adds something to the experience, when you exceed my old amps comfort zone of 80 to 100 watts.


I must be taking the same placebo.

I'm with Zimm on this one.


Me too.

I'm with Bug on this one. \:\)
Posted By: Spoiler Re: Added an Amp...WOW, kinda. - 04/25/09 08:33 PM
 Quote:
Anyone have those M2200s floating around? How hot do they get?

I've been scared off by the amp manuals suggesting you have a separate 15A circuit for them, yadda yadda, tons of clearance, yadda yadda, since I don't have much of either.


If you crank them with music at 90-100 db average, yep, they'll get hot after about 20 min. I've kept them going alot longer than that (when 1st testing them) without shutdown. Of course, if you can stand music for that long at those levels, you're a better man than I. \:\)
Mine are stacked on top of each other with about 3" clearance above. No need for separate circuits.
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/26/09 04:55 PM
Well, the Crown amp experience was helpful. I know I want an amp, but the Crown's noise floor is too high (S/N is about 90, and THD is around .5%). Researching a bit, it looks like the QSC is a better option for my uses. QSC actually has several THX certified amps using their H-class amps. THX Cert Their noise levels are much lower (S/N >100 and THD is <.05). I can't find the THX amps locally, but the GX line uses the same H-class amp design and looks similar so I'm going for it today. I'll let you know.

But I have to give the Crown two thumbs up, other than a bit of noise during dead quiet sences, it is great. Hopefully the QSC will do the same without the noise.
Posted By: chesseroo Re: Added an Amp...WOW, kinda. - 04/26/09 08:49 PM
 Originally Posted By: JohnK
Misti, amplifiers simply don't work that way; they have no capability of performing a miracle by making speakers "come alive sooner" at lower volume level. Volume is volume.

Actually John, such an observation could be perceived if the amp has a higher gain to signal ratio than another although that is an observation of SPL and not sound quality per se.
Posted By: chesseroo Re: Added an Amp...WOW, kinda. - 04/26/09 08:51 PM
 Originally Posted By: pmbuko
LT61, even inexpensive amps have low (< 0.1%) THD now.

Didn't BrenR put up an mp3 demo of distortion awhile back that was rather enlightening?
Thinking a person can hear <1% THD is like thinking you can hear a mosquito fart at 100 metres.
\:\/
Posted By: Wid Re: Added an Amp...WOW, kinda. - 04/26/09 08:56 PM
Yes he did, here it is.
Posted By: PeterChenoweth Re: Added an Amp...WOW, kinda. - 04/26/09 08:58 PM
 Originally Posted By: chesseroo
 Originally Posted By: pmbuko
LT61, even inexpensive amps have low (< 0.1%) THD now.

Didn't BrenR put up an mp3 demo of distortion awhile back that was rather enlightening?
Thinking a person can hear <1% THD is like thinking you can hear a mosquito fart at 100 metres.
\:\/


You live in Canada. If a mosquito could fart, those B-52 sized mosquitoes you've got up there would present the best chance to actually hear one from 100 meters away. ;\)
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/26/09 09:00 PM
Picked up the QSC GX5 (QSC) - even swap for the Crown, so $350. Better stats, 600w/c at 8 ohms with one ch driven (700 at 4 ohms with 2 ch driven) at .1% THD, with .05%THD at non-peak volumes. Initial testing shows it is the same as the Crown (as it should be) but it does have a touch less noise in quiet sections which is what I was aiming for.

I only tested two songs from Dire Straits, but as my reference material it still supports my opinion that the extra clean horsepower does make a difference. On "You and Your Friends" the plucks that had a bit of harshness on the Denon on loud peaks sound, on the QSC, as clean as the Denon at lower levels. And again, the peaks are just more dynamic. Hitting 105db was rare with the Denon on this song. Now the db jumps from 94 to 105 in instantaneous peaks. You can't even hear the "loud" peak, but the db meter (set to fast, Max Hold) shows the peaks are happening - which were not there before on the Denon. Makes sense when you consider Home Theater Mag said my Denon 3300 starts to clip the peaks of the signal at less than 80 watts. So my AVR clipped these peaks off due to lack of clear signal amplification, now those same signals play unclipped. Not hard on the ears (for these instantaneous peaks) but running at 100+ does need to be done in short sessions. That Monk did not go deaf by illness!

P.S. - the QSC has a 6 year warranty and includes unbalanced inputs, which takes out the need for the converter I had for the Crown.

Question: would the noise floor from the Denon pre-out be lower if I up the channel level or lower it? Assuming the separate amp is not adding anything, I'd like to maximize the sonic quality of the output signal.
Posted By: CV Re: Added an Amp...WOW, kinda. - 04/26/09 09:03 PM
Thanks for posting your findings, Zimm. That amp sounds like a great deal.
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/26/09 09:39 PM
No problem. Must mention, after running it a while, I can hear the fan running. Louder than a PS3 fan. Not good. Need to address this issue.
Posted By: Wid Re: Added an Amp...WOW, kinda. - 04/26/09 09:49 PM

Rotel \:\)
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/26/09 10:32 PM
 Originally Posted By: wid

Rotel \:\)

Agreed. But at $2,500 to get similar power, I just can't get there yet. \:\( I need other parts first. For $500, I'd upgrade. For $350 I'll upgrade and troubleshoot until I have the package worked out.

Just worked out a nasty ground loop hum caused by the coaxial connection to my DVD/CD player. I thought the amp was doing it, but turns out it was just amplifying it. Go figure. \:\)
Posted By: Lorenzo1000 Re: Added an Amp...WOW, kinda. - 04/27/09 01:04 AM
ATI Bridge-able to 450 watts/ch at 8 ohms

Acurus

If you have any interest in the pre-owned route- good values for the $$$$
Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/27/09 08:58 PM
 Originally Posted By: kcarlile
Anyone have those M2200s floating around? How hot do they get?

I've been scared off by the amp manuals suggesting you have a separate 15A circuit for them, yadda yadda, tons of clearance, yadda yadda, since I don't have much of either.


If you'd like, I'll haul my MPS-2 over or you can bring the M80's over(amp weighs 115 lbs and disassembly) and we can test them with my receiver first and with the MPS-2 after. Not M2200's but you can see if the amp makes a difference or not.
Posted By: mistico Re: Added an Amp...WOW, kinda. - 04/27/09 09:01 PM
I only see two problems with the above:

1. You'll want an Amp
2. I'll want M80's(shutdowns \:\) )
Posted By: Ken.C Re: Added an Amp...WOW, kinda. - 04/27/09 10:10 PM
Heh... unfortunately, with the new addition to the fam, now's a really bad time for auditions.
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/28/09 01:46 PM
QSC G5 Update: Fan noise is a problem in small room with an open amp rack, and low volumes. I wish I could route my signals so that AVR ran until I wanted the QSC beast turned on. If I keep it, which looks very likely, I'll swap out the fan for a lower CFM model. Can't complain about the sound; forgot to turn the sub back one for two days and didn't even notice until I turned on Jurassic Park (on TV) and realized the LFE was missing on Dino steps.

I read the QSC and AVS forums a bit, and I must say it is really funny to see the pro side and HT cross streams. [Ghost Buster fashion!] The pro amp designers warn HT users not to use a pro amp because the power is so much more than the stated max of the speakers. The HT folk beg for more clean power. The Pro amp folks can't understand all the questions about THD, S/N, etc., and the HT folk can't understand the discussions about power consumption and 2 ohm loads.

QSC position of "audiophile" v. pro amps is that the only difference is colling capacity (loud fan) and "bling". So what happened when QSC re-badged a PLX line amp as a HT amp - the price jumped up to match HT offerings. Maybe it is all hype. Heck, on guy compared the QSC to McIntosh and Halo for a month and came away in favor of the cheap QSC. Wild stuff.
Posted By: jakewash Re: Added an Amp...WOW, kinda. - 04/28/09 02:48 PM
Thanks for the updates Zimm. I think I now know that I can get a pro amp, I just have to enclose it in its own area on the equipment rack ;\)
Posted By: tomtuttle Re: Added an Amp...WOW, kinda. - 04/28/09 03:53 PM
Those of us that don't live in swamps could consider putting the amp(s) in the basement or crawl space and routing cables accordingly.

;\)
Posted By: fredk Re: Added an Amp...WOW, kinda. - 04/28/09 05:07 PM
Thats very cool stuff Zimm. Thanks for being our audio lab rat.
Posted By: Zimm Re: Added an Amp...WOW, kinda. - 04/28/09 05:42 PM
 Originally Posted By: fredk
Thanks for being our audio lab rat.


As long as my hair grows back, I'm cool with it. But does that mean I can stop smoking now? Every time I hit the volume up button a cigarette pops out the amp, so I figure I should keep smoking them.
Posted By: JaimeG Re: Added an Amp...WOW, kinda. - 04/28/09 06:23 PM
 Quote:
Every time I hit the volume up button a cigarette pops out the amp, so I figure I should keep smoking them.

Darn, so you're not getting zapped when you reach for the cigarette huh? The experiment has been compromise guys
Posted By: fredk Re: Added an Amp...WOW, kinda. - 04/28/09 08:06 PM
\:D
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