Opinion please- new amp?

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mixsit

Opinion please- new amp?
« on: 19 Sep 2010, 09:31 pm »
I wasn't actually in 'new amp mode but ran across these in another group;
http://emotiva.com/xpa2.shtm
 
I'm currently running the Adcom GFA555. I almost never see this thing clip- I would really have to be pushing them and I only occasionally listen that loud (and then they would only light up' given old school mastered stuff that actually has some peaks left in it.  :P
But I do notice a bit of strain up in the 100spl range (Continuum's –I wouldn't expect and drive the Mini's like that).
Frankly I don't know if that's the amp running out of steam, the speakers. Could be the ears.. but based on other experience I think not.
And I'm still not sure I should really expect 'unstrained at these levels out of our 1" dome, but I have heard this kind of headroom in 'horn loaded well past the 100db range. (And really, I want to stress this is the only thing I can think anyway near 'lacking here. Short of having a sepperate, dedicated and less accurate 4-way $10K fun system..? Not needed. Not going to happen.  :lol: )
The other thing is XPA2 is but a small jump in real headroom presumably. 200 at 8 ohms on the Adcom vs 300.
There are also the XPA1's but that would be quite a bit lot larger jump (.. a pair $$).

Ok. Reality check please.

Help... Bob..?  Wink2 :inlove: :wave:

Oh and an add.. the Adcom could then go to the mini's' w/o out me having to switch back and forth..  :?

ooheadsoo

Re: Opinion please- new amp?
« Reply #1 on: 19 Sep 2010, 10:40 pm »
Some of us have had good experiences with the DAC amps like the 4800A and the Cherry series.  I have a 4800A that I am very happy with paired with the TP3.0.

Per their amazon ad: more than 380Wpc into 8 ohms, more than 640Wpc into 4 ohms, Bridgeable for Massive Power (>1000W into 8 ohms)

I got mine used for less than a pair of emotiva.  Definitely happy with it.  You can talk to Tommy, the owner/engineer, right here on AC too.  The sound is clean and clear, with power on demand.  You know, I see that they are listing some of their audiogon auctions with a really reasonable starting price, and they are willing to end the auction early if you contact them. 
« Last Edit: 19 Sep 2010, 11:41 pm by ooheadsoo »

lonewolfny42

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Re: Opinion please- new amp?
« Reply #2 on: 20 Sep 2010, 04:44 am »
Emotiva has a 30 day trial period for you try their products in your home...you could try it.

I read mixed reports about them...but worth a shot...cost is low.

As ooheadsoo mentions....the DAC amps work well with Bob's speakers....heard them many times.

Most important with Bob's speakers....good , clean , strong power amp...makes the speakers really come alive.

Good luck.... :thumb:

mfsoa

Re: Opinion please- new amp?
« Reply #3 on: 20 Sep 2010, 05:01 pm »
Wow I can't believe you got two Digital Amp Co recommendations before I could say anything!

Yes, they work very well on Bob's speakers - Very clean, excellent bass etc.

Outstanding transient response w/ great dynamics (same thing, I guess) that seems to match these qualities that Bob's speakers are great at.

Reveiw in the new Affordable Audio mag.

-Mike


turkey

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Re: Opinion please- new amp?
« Reply #4 on: 20 Sep 2010, 05:38 pm »

I'm currently running the Adcom GFA555. I almost never see this thing clip- I The

I've listened to both, and seen the insides of both. I feel the Emotiva products are better than the Adcom ones.

I don't know whether or not you'll hear a difference, but you can find out for the cost of shipping.

Along with the XPA-2, you might also look at a pair of the UPA-1. You'd still be getting as much or more power than your Adcom and many people like the looks of monoblock amps.



bhobba

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Re: Opinion please- new amp?
« Reply #5 on: 20 Sep 2010, 11:07 pm »
Another amp I have heard that works well with Bob's speakers are the AKSA amps:
http://www.aksaonline.com/

I have a NAKSA and it works excellently with ML1's which are similar to Bob's speakers:
http://www.aksaonline.com/products/products_NAKSA70.html

Note they are not power demons like the DAC amps so you won't be able to really wind up Bob's speakers which they rather like.  But if you can live within that then I think it is a great choice.

Thanks
Bill

mixsit

Re: Opinion please- new amp?
« Reply #6 on: 21 Sep 2010, 04:31 pm »
Thanks for all the help and info guys (folks' Sorry!
I followed 'DAC to some reviews at AffordableAudio.org, and they definitely look very good as well. Also there is some more um, very interesting stuff on Emotiva.

But I'm still hoping for someone  :roll: to jump in on the base question -(not bass'  :P  regarding the higher level sonic conditions I mentioned (i.e. amp vs speaker.. a bit of each?

rms

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Re: Opinion please- new amp?
« Reply #7 on: 26 Sep 2010, 11:19 pm »
Hey Mixsit - I power my Continuums with a DAC 4800A and it can be positively frightening. It will go much louder than anybody should be exposed to with no hint of strain whatsoever. But it also does low volume extremely well. Detail is fantastic, it is very fast and accurate. I couldn't be happier. If you have any other questions specific to the pairing with the Continuum's (or Mini's, I have both) please let me know.

Aether Audio

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Re: Opinion please- new amp?
« Reply #8 on: 28 Sep 2010, 12:52 am »
mixsit,

Quote
I'm currently running the Adcom GFA555... Help... Bob..?

My friend.. you're tracking and mixing LIVE music.  You should already know what I'm gonna say.  :duh:  After all these years of me harping on the subject of power, power, power!!!?

I don't care if you are using compressors and limiters (which there's no getting around), I'll still bet anything you're not using as much compression as is used in most of the commercial music everybody listens to.  Even then, most audiophiles have no idea how often they are actually clipping their amps.  Well... you're one of those guys too, but on steroids!

Does anybody here know what an amp in clipping sounds like?  Actually, you know far more than you realize, it's just that you don't realize.  OK... I'll really go out on a limb and tick everybody off.  Most of you know what good "Hi-Fi" sounds like, some more than otheres - but that's about it.  On the other hand, if you actually *knew* what real, live music sounded like, there'd only be a couple dozen or so audio manufacturers even in business.

You don't believe me?  Do the math.  A typical pair of speakers of 87 dB sensitivity will produce 87 dB SPL at one meter.  If you listen at 3 meters (about 10 feet) the SPL drops -9.7 dB to 77.3 dB SPL.  To seriously listen you're going to want to get back to 87 dB or so.  To make the math simpler, let's just round it up to needing 10 dB more power.  OK, average SPL is now around 87 dB during certain musical passages, so you're using a measly 10 Watts per channel.  No big deal - right?  Well... but you're listening to a good digital source, so transient peaks come along with many plucked guitar notes and drum/cymbal strikes and what-not.  Those can easily be 10dB higher than the average signal, even though they don't last for more than a millisecond.  To keep from clipping them though, now you need 100 Watts/ch.

That's not too big of a worry as a lot of guys have 100-watts or a bit more available from their amps.  Uh-ohhh... what if that peak is only 3 dB louder (+13dB)?  Now you need 200 watts/ch.  At +16 dB you need 400 watts and at +20dB you need 1kilo-watt!  Is a 20 dB peak "common"?  Probably not common, but possible.  The better the recording, the more probable it will be.  Now... what if you "push" the volume a bit to where you're listening at 90 dB SPL or a bit higher at times... like in a real concert?  All that headroom you "thought" you had is now long gone and now you're clipping the amp pretty frequently.

But... those peaks are so fast and short in duration compared to the average power you're using, you don't "hear" any clipping.  Only when you're clipping the *snot* out of the amp do you typically hear it as such, but if that happens you know it and turn down the volume.  In  lieu of such obvious clipping, what do you hear?  You hear...

Quote
But I do notice a bit of strain up in the 100spl range

I'll bet!!!

Strain is a good word.  Brightness, listening fatigue... anything along those lines are common observations.  Mixit is talking about 100 dB SPLs on top of it.  For the guy that has a 50-watt/ch amp... what do you suppose he's hearing MOST of the time?  "Yep... gotta get a new preamp to smooth things out a bit."  My brain hurts.  :duh:

If you ever saw what the FFT of a clipped amplifier waveform looks like, you'd understand.  Harmonics galore and out to infinity!  There ain't no preamp, DAC cable or you name it that's gonna fix the problem.  You need a new power amp.  While you're at it, get the biggest/best sounding one you can afford and lay the issue to rest once and for all.  If you do, THEN you can spend the rest of your time and money tweaking every other gizmo in the chain to your little heart's conntent... and actually be able to hear just what those tweaks are REALLY doing - good or bad.

Mixsit, I suspect you amp's clipping indicators have integrators on them.  The trick is to combine that with a pulse stretcher so the user only sees severe levels of clipping (after integration) and the LED stays on long enough for the human eye to see (as a result of the pulse stretcher).  I'll bet that if you had a Crown amp of the same power with their IOC indicator, you'd be seeing that thing flashing like Christmas tree lights.  If you don't believe me, listen to RMS.  His Continuums are older/more feeble than yours... and he ain't complaining. Of course, how many watts per channel does he have? :wink:

Take care,
-Bob
« Last Edit: 28 Sep 2010, 02:54 pm by Aether Audio »

bhobba

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Re: Opinion please- new amp?
« Reply #9 on: 28 Sep 2010, 03:01 am »
Does anybody here know what an amp in clipping sounds like?  Actually, you know far more than you realize, it's just that you don't realize.  OK... I'll really go out on a limb and tick everybody off.  Most of you know what good "Hi-Fi" sounds like, some more than otheres - but that's about it.  On the other hand, if you actually *knew* what real, live music sounded like, there'd only be a couple dozen or so audio manufacturers even in business.

Yea all true - even though I tend to put up with it because I listen at low to medium levels.  With my trusty SPL meter I know I rarely, if ever, exceed 80db, if that, which means I can get by with a bit less power.  But wind it up a bit and I would have problems.  Interestingly I know one guy, a real purist type, that has software that preprocessors digital audio to the maximum level so the peaks are at the top level.  Then he feeds his DAC direct to the amp - no volume control.  Man when I heard it did it ever sound good.  And one reason for that is there is zero possibility of clipping.  However he only used a 3w amp but has some extremely sensitive speakers and like me listens at medium levels.  If you tried the same trick with Bob's speakers you would be surprised at the power you would need if you wanted loud levels instead of the medium levels that 3W job produced.  500W in that scenario would not be out of the question.

Thanks
Bill

Aether Audio

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Re: Opinion please- new amp?
« Reply #10 on: 28 Sep 2010, 02:56 pm »
Mixsit,

PS. Come to think of it, your clip indicators may not have integrators - they just may (probably) not have the pulse stretching circuit.  If that's the case... fast, short duration clipping does not illuminate the LEDs long enough for the human eye to detect.  That's why Crown uses the pulse stretcher in their IOC circuit.  Without it, the fact is that by the time the LED lights up long enough to be able to see, you're already well into gross clipping.  That was one of Crown's many amplifier improvements over the competition.  I wish everybody employed the Input/Output Comparator circuit in their amps (except I think its patented).  That circuit not only shows all clipping of even the shortest duration, but also detects ANY form of distortion - including slew rate distortion ( a tough one to detect).  If there's ANY difference between the input and output waveform (other than gain), the IOC lights up and let's you know.  Of course, if everybody did use it, you'd all be demanding MUCH larger amplifiers!  :o

Take care,
-Bob

mixsit

Re: Opinion please- new amp?
« Reply #11 on: 2 Oct 2010, 05:47 am »
Ok.. I've just got back (switching gears from a spell of 'full live gig mode.  :bomb:
This is encouraging.  And this..
Hey Mixsit - I power my Continuums with a DAC 4800A and it can be positively frightening. It will go much louder than anybody should be exposed to with no hint of strain whatsoever. ...
  :wink:
It occured to me, I have a QSC (PLX-1804) which may indeed sound funky in any number of ways, but I could at least try it out for a headroom experiment.
Bob's spec says '250 long term' –but I still keep thinking 'the poor little tweet! :green:

lonewolfny42

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Re: Opinion please- new amp?
« Reply #12 on: 2 Oct 2010, 05:59 am »
That "poor little tweet" will be fine.... :wink:  :weights:

mixsit

Re: Opinion please- new amp?
« Reply #13 on: 2 Oct 2010, 06:06 pm »
Cool
 8)

I want to believe.. I do.

Guess I'll find out.

Hi Bob!  :beer:

rms

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Re: Opinion please- new amp?
« Reply #14 on: 26 Oct 2010, 03:19 pm »
It occured to me, I have a QSC (PLX-1804) which may indeed sound funky in any number of ways, but I could at least try it out for a headroom experiment.

Some of the Pro Sound Reinforcement amps are great for this. In fact most studios use them in their monitoring chains - you don't usually see what we might normally think of as "Audiophile" brands in most recording or mastering studios. That said I have an older Hafler poweramp with some mods that is an absolute brute and sounds amazing. It is very fast and accurate, has tons of headroom, and the bass is nearly as good as the DAC 4800A. But the DAC does sound better, it really is a fantastic amp. Try your QSC out, you may be pleasantly surprised when you pair it with the Continuums.

ooheadsoo

Re: Opinion please- new amp?
« Reply #15 on: 28 Oct 2010, 02:55 am »
The only thing is that the more powerful prosound amps tend to have fans.

Karsten

Re: Opinion please- new amp?
« Reply #16 on: 28 Oct 2010, 10:49 am »
Then he feeds his DAC direct to the amp - no volume control.  Man when I heard it did it ever sound good.  And one reason for that is there is zero possibility of clipping. 

To be honest, I never heard a preamp that I really liked, There are some good ones around, but all I have evaluated have flaws. I don't know why making a good analogue preamp is so difficult? In theory it should be simple... :)

Many seem to be skeptical about digital attenuation, and there are many theories about why this is a bad thing. It just seems like the skeptics takes for granted, that attenuation in the analogue domain is perfect, which it is (usually) not..

I'm also going directly from my DAC into the power amps, which is by far the most detailed, open sounding, dynamic and neutral solution I have come across.

Before getting my DAC with build-in digital attenuation, I just used the attenuation i Windows Vista, which is pretty good.

It does however take a pretty good sound card (Like Lynx AES16e) and software like J.River mediacenter, to get up to par with or exceed the performance of a good CD drive.

Anyway, less can do it, if you just want to "preview" the effect of skipping the preamp. Even though the digital front end may not be optimal, it is quite easy to determine which taste the preamp has..

Regards,
Karsten


Albireo

Re: Opinion please- new amp?
« Reply #17 on: 29 Oct 2010, 05:21 pm »
To be honest, I never heard a preamp that I really liked, There are some good ones around, but all I have evaluated have flaws. I don't know why making a good analogue preamp is so difficult? In theory it should be simple... :)

Many seem to be skeptical about digital attenuation, and there are many theories about why this is a bad thing. It just seems like the skeptics takes for granted, that attenuation in the analogue domain is perfect, which it is (usually) not..

I'm also going directly from my DAC into the power amps, which is by far the most detailed, open sounding, dynamic and neutral solution I have come across.

Before getting my DAC with build-in digital attenuation, I just used the attenuation i Windows Vista, which is pretty good.

It does however take a pretty good sound card (Like Lynx AES16e) and software like J.River mediacenter, to get up to par with or exceed the performance of a good CD drive.

Anyway, less can do it, if you just want to "preview" the effect of skipping the preamp. Even though the digital front end may not be optimal, it is quite easy to determine which taste the preamp has..

Regards,
Karsten

Tastes being what they are, I can understand why someone would put a fat-/rich-/smooth-/whatever-sounding preamp in between source and amp as a tone control. But I'd also put in another vote for the direct-to-amp DAC approach. I remember trying to upgrade to "traditional" analog amplification from a long-term setup featuring a Bel Canto DAC3 into NuForce 9 amps (driving the NuForce S-9, and eventually Timepiece Minis), auditioning this and that preamp/amp combo, and the transparency losses just killed any competitors. And one of those preamps was a custom Placette PLS too ....

In my limited experience, the culmination of the pursuit of transparency was the "power DAC" where the DAC essentially drives the speaker directly. This is the TacT/Lyngdorf route. I've tried to stray away from my current Lyngdorf TDAI2200, to no avail. It makes even the Bel Canto/NuForce setup sound somewhat cloudy, grainy, and small by comparison, and I seriously loved that setup! Short of ultra-kilobuck systems (which I cannot afford), I'm fairly certain this is the best I can achieve in terms of dynamics, neutrality, and transparency.

BTW, Karsten is right about having a good source for a direct-to-amp DAC approach. I also use a Lynx AES-16 (SRC, in my case), with Foobar.