Class D is just Dandy!

Okay so, a couple of votes for a $60k product....

madavid

I strongly wncourage you to read this threa. At least skim it. It is filled with glowing recommendations for Class D. 

You can disagree, but there are other threads for trashing class d and I would appreciate it if any detractors took their coments there.

Best,

E

Absolutely all that and more.

I was a long time tube and class a guy,not anymore.

Offcourse it's system dependent.

Kenny.

madavid0

Every moment of every day

Have any of you guys who claim class D is just fine manage to get musical, non-fatiguing sound and soundstage depth?

@autre maybe the amps had different input impedences?

@autre

The Wyred 4 Sound STi v.2 integrateds were on my list. They do not have a dac. The Wyred gear is very well reviewed and there are many happy users out there.

http://https//www.wyred4sound.com/products/integrated-amps/sti-v2-series

Cheers,

Scott

Thanks for the NuPrime recommendation. I'll check it out. 

That's funny Erik, I hadn't noticed people were mud-spelling it!  It helps to have two other acquaintances with the same spelling as you. 

I eont take take this wonderful thread too far off track but I had two follow up questions. 1) anyone know of some good "standardly" equipped integrateds (no onboard dac)?  And 2) as was mentioned in an early post, I had encountered RF issues with one of the amps. Curiously it was only through the line inputs, and while connected to the CD unit. This only occurred with one of the amps and not the other even though all the other pieces including wires were kept the same. Any ideas?

@autre

Thanks, and thanks for being among the first to spell my name correctly.

Best,

E

@autre 

NuPrime IDA-16; I really enjoy mine. It has 200 watts; build quality and functionality is excellent and it sounds great.


http://http//www.nuprimeaudio.com/index.php/products/amplifiers-and-preamps/integrated-amps/ida-16.html

Cheers,

Scott

Erik, as many others have said, thanks for starting this thread. I've found it extremely informative and quite entertaining. I'm new to the Class D amplifiers but love them because of their sound and ability to run cool which is perfect for the tight fitting cabinet that I have.

By pure chance thetwo integrated amps I've home auditioned were Class D: the Rogue Sphinx and the Peachtree Nova 125 SE. I was interchanging the two in my system which includes Kef ls50s and an old Onix XVD-88 CD player. The sound from both was phenomenal, but different from each other. Instrument representation seemed very accurate and vocals were gorgeous. Of course my descriptions should be taken with a grain of salt since I'm not an audiophile by any means. Both amps in my room sounded great but each portrayed music with their own distinct signatures that definitely made me curious to try some others. 

Given this does anyone have suggestions for a nice Class D integrated that they like?  Price range would be in the neighborhood of the Rogue and Peachtree ~$1500. 

It's also important to say, differences are not better or worse necessarily. Maybe two amps sound different. Is one better or worse, is it worth caring about? Are you trying to make your ears more sensitive or enjoy music and movies more? :)

We get all confused in our goals (Me too!) so it's important to be clear. Audiophiles too often think the next different thing is "better" when it's not. I think even John Coltrane was guilty of this, and would make endless takes until someone told him "You can't play it any better, just different."

Best,

E

@jrunr

I would listen to them. :)

Bridging is a tricky thing, possibly involving slightly more circuitry at the front end, and possibly lower damping factor (Higher impedance). How much is audible? Is a higher 8 ohm power rating going to help you drive speakers better? (unlikely)

The real question for me would be whether you need 500 Watts / Channel. :) The basic 200W/ch models are overkill for almost everyone. In a modest configuration (< 8 channels) you could have a lot of reserve power.

Depending on the costs involved, you might also want to play with the 400 W/Ch nCore kits available from Hypex. I’m not sure how they compare to the ATI multi-channel amps.

Best,

E

E,

Do yo think there would be sonic differences between the modules?

Hi @jrunr

Regulator or not, the question is whether they all share a transformer, that's where the money/size/weight is.

If I were designing them, I'd stick to 1 power supply model, and add or remove amp modules as necessary.

Best,

E

I don't know if that would make that big of a difference as the amps are not really modular and can't be modified to add or delete channels once built so I assume ATI has some regulator in the mix once they are built...

I really just wonder what the sonic differences would be between the regular and the bridged modules, if any.

Here is the relevant part:

The AT52XNC amps are rated at 200W RMS per channel at 8 ohms
with300W RMS at 4 ohms and are available with 2 to 8 channels.

The AT54XNC amplifiers use two N-Core modules per channel in a differential bridged output configuration delivering 500W RMS per channel at 8 ohms and 900W RMS at 4 ohms. The AT54XNC amplifiers are available with 2, 3 or 4 channels.

It seems the 54xNC series are bridged, and therefore have half the channels of the 52xNC models.

Since the power supply is linear, ATI is limited in what they can put in a single chassis. A 1,600 watt linear supply is BIG and HEAVY and EXPENSIVE.  This wattage / size limit is driving everything else.

If you limit the channels to half, you can double the per channel output (more or less).

Personally, I'd rather go with a pair of unbridged 52xNC models, but limit the channels. 3 or 4 channels in each would give you a lot of power supply capacity/channel and ensure you had the best low-impedance drive possible.

Best,

E

So I just checked out ATI's multi-channel nCore amplifier. It looks really interesting, except packing that many channels (8) into a single chassis limits the total simultaneous output.

If you only have a pair of hard to drive speakers, this should not be a problem. Also depends on what you mean by "hard to drive". This is a big range.

Still, 8 x 200 watts = 1,600 watts total. That is a lot of output!!

Best,

E

@jrunr

No, not necessarily. :)

Usually you can tell by how low a speaker impedance it is rated for (8 --> 4 --> 2 --> 1 Ohm) and how well the power doubles each step down in impedance. So for a 50 watt amp the best should put out 400 Watts at 1 Ohm. :) :

50--> 100 --> 200 --> 400

This is how Krell go their fame, with a 50 Watt class A amplifier that output 400 Watts into 1 Ohm.

Of course, these amps are beefy, but also usually ridiculous. :)

It's also important to understand exactly where your speaker is hard to drive. Digital amps tend to do better in the bass than the treble, which is good because most conventional speakers are hard to drive in the bass. nCore modules are famous for being less sensitive to where your speaker is hard to drive.

Best,

E

Do you know if there is a difference between the 543NC and the 523NC?  I know there is more wattage, but does that equate to better sound for difficult speakers?

@jrunr, I don’t have any direct experience with 7B’s but I was in similar situation as you. I own a pair of B&W 800’s and they are quite power hungry. After sticking with Class A/B amps for couple of years I begin experimenting with Class D amps.

If you’re looking for multi-channel amp, I would give it a serious consideration to ATI 500NC series amps. I have been listening to 544NC amp for a week now and couldn’t be any happier. While amp is still settling, the amp got gobs of power and finesse to drive my 800’s with ease. Most dealers have 30 days return policy minus the shipping so you can audition this amazing and fairly inexpensive amp risk free.

I’ll probably order their 543NC - 3 channel amp soon to complete my 7.1 HT setup.

http://ati-amp.com/AT52XNC.php

PS: I have also heard high praises for Bel Canto REF600M’s.

I have some Aerial Acoustics 7B and CC3b speakers that are notorious for being hard to drive and loving very large amounts of power.  Has anyone used any Class D amplification on these?  If so, how was the synergy and sound compared to a more common class A/B amp?  I am looking to find out what would be the best solution for these.  They already sound great and image very well, but I want to take it up a large notch and power them adequately so I can get the most out of them.  Anyone have any suggestions?  Comments on possible class D amplification for them?  Advice? 

I meant...a Rotel 158x amp

I've owned a total 158x amp and peach tree nova/220 equipment....both sounded great.  Punchy...clean...not strident...  Unless you are into uber-syrupy sounding tubes or something...i can't imagine one not  liking the sound. I have heard that wyred4sound equip can be bright sounding...but have no hands-on experience.

@kdude66

Sounds like something I've said, about other things though. :)

Best,

E

Hello all,
I read this statement on another forum and thought it sums up my outlook,each to there own Offcourse.

"We can hear everything we measure, but we can't measure everything we hear. Let your ears be your guide."

Kenny.

Ah, fine. :) That's fancy.

All we really need is a signal generator, and voltage meter at a couple of frequencies.

Best,

E

Erik said:

REW is great, but measuring the speakers adds a ton of confounds. I say this as a speaker maker and integrator. And that's fine, but what I'm personally after is to understand how well these amps do electrically, as that will be the most clear. 

You can use REW to measure impedance and electrical transfer functions too (since Ver5).  Nice link on impedance measuring:
http://www.avsforum.com/forum/155-diy-speakers-subs/1340740-lilmikea-s-diy-impedance-measurement-jig...

By the way, I just ran the numbers on that.

Based on output impedance, and assuming a 1 Ohm speaker impedance the ICEPower 250 A would droop around 2.2 dB at 20 kHz. That’s not unacceptable, and in line of what a tube amp would do to a lot of normal speakers.

Pro: A gentle glare reducing effect.
Con: Removes air, dulls top end.

A bigger concern to me would be the speaker efficiency and output power of the modules used.

Also, one not well known thing about these modules is that their cooling matters a great deal. The power rating increases with better heat sinks. Some manufacturers stick these in sealed speaker cabinets but the power gets derated.

Best,


E

If it were possible to measure, I'd ask for these amps to be measured with a 1 Ohm resistor at 2.83 Volts. :)  About 8 Watts. Let's see that first.

REW is great, but measuring the speakers adds a ton of confounds. I say this as a speaker maker and integrator. And that's fine, but what I'm personally after is to understand how well these amps do electrically, as that will be the most clear.

If we try to measure just the speaker/room we won't have any idea what is due to the speaker, and how much is due to the amp/impedance interaction.

If I remember where my oscilloscope is I may do this with mine.

Best,


E

Hi John,

Thanks very much for the tip on the microphone and the software. I will check it out.  Sorry you have to give back the Scintillas.

Erik, Agreed. The room plays a big part as well and among other things.

Kenny, Looking forward to your review, especially the difference compared to the Ncore.

If anyone here interested in hearing the H2O, I am willing to send it for you to test drive in your system. No string attached of course. I would be very interested to read your review on the differences, especially compared to the Ncore and other icepower amps that you have.  Please remember though, the H2O has 8 kohm input impedance so you should have an appropriate preamp to drive it properly.

Henry

I have a new Red Dragon S500 I eventually will try out,haven't got too it yet,will be a diff. class d module then the ncore's I do have.
I will write a comparison review when I do try them.

Has anybody else tried this amp and what speakers do you use them with.

Kenny.

Hi @h2oaudio

Oh, agreed. In many cases a top octave roll-off may be much better sounding than a flat amp.

Also room dependent.

Best,


E

Kenny

Unfortunately, I am not very well equipped with instruments to perform such tasks.

Do you have a computer / laptop with audio out?  Then all you need is REW (Room Equalization Wizard) which is free and a mic.  You can get a USB mic with a reference curve here for a very reasonable price.
http://cross-spectrum.com/measurement/calibrated_umik.html

- John

Henry

It is very rare to find a Scintillas owner.  Are you located in Texas?

Former owner I'm afraid.  Parted with them many years ago - the original owner wanted them back.  Today I have a system based on the BG72 ribbon and 6 Carver hex cone woofers, and I just finished restoring a set of Carver Amazing Platinums with NOS ribbons and new woofers.  

- John

P.S.  Yes, I'm in Texas, the DFW area.

Erik,

Just to add a bit about the Scintillas. Sure, they are closer to a short over the entire audio frequency spectrum than any other speakers to date. It is not that hard to design a conventional linear class A amp to deal with that which I have done. But what compounding to the low impedance problem is their efficiency, and if I remember correctly, Stereophile’s measurement came up with was in the mid 70 dB or so. And Here is where it is an equally challenging task to deliver substantial power into such low impedance and inefficient load.

Henry

Kenny,

Unfortunately, I am not very well equipped with instruments to perform such tasks.

Henry

John,

It is very rare to find a Scintillas owner.  Are you located in Texas? 

Henry

Henry,
I would be more inclined to measure the in room response of your speakers and see what you get.

Kenny.

Erik,

There is no misunderstanding at all and I apologize for my writing not being very clear at times. I understood completely what you asked, and that is you want to see is the real frequency response plot of the amp while driving such a load and also to determine what the 3 dB points are for both frequency extremes. Again, the answer is NO. I have not done the measurement. Because of the output filter of the icepower, and most of class D amp, I would speculate that there will be some high frequency attenuation at very high frequency due to the impedance raise of the inductor.

What I meant by lowest output impedance of the amp, especially completely flat up to the extreme treble region, is not necessarily always good is that it depend on the system. IMHO and IME, extreme low output impedance amp does not sound very good when mating to a highly damped loudspeakers. This is the very reason why tubeohiles really object to solid state amps, especially those with lots and lots negative feedback, to lower output impedance and distortion. The end result of such mating results in a sterile and one note bass and everything is too tightly control. Therefore, there is not much left in terms of air around instruments, much smaller soundstage, Closed-in midrange,
harsh and sterile treble etc... I am speaking strictly in terms of conventional discrete transistor design. I have designed, built, test, tried this and tried that for as long as I can remember. I agree with you about experience. There is no substitute for that.  Also, Absolutely! Apogee did put Krell on the map for sure.

Henry

George,
I bet that combo sounds spectacular.

Should have seen/heard the 90’s system, similar amps but water cooled, doubled stacked Acoustat 2’s with Magnat Plasma MP-02 Tweeters above 10kHz. esl panels crossed over at 80hz to Kef B1814 bass drivers in ported 12cu ft encosures FS at 18hz, tuned by the man himself Neville Thiele (rip), some rich dude from Singapore came to Australia just to buy it all from me, after it was reviewed in Stereophiles sister mag in HK.

Cheers George

Where do you get your data on the Scintillas?

Sorry my bad on the phase, looked at the graph wrong.
But not on the impedance, still 1ohm in the bass, and again it seems from your measurments at 1.3khz, no place for class-D or tubes or Mosfets, they will behave like tone controls or just give up.

"True, you could with some effort, re-wire your Scintillas at home for 4 ohm operation, but with a 6dB loss in voltage-rated sensitivity. At 1 ohm, MC estimated the sensitivity to be 73dB/1W, noting that, ’Consideration also needs to be given to the peak current demand of the Scintilla at 1ohm. Taking an average impedance of 0.9ohms, a Krell KMA-200 on full song will provide up to 60V peak. Assuming minimal cable losses, the Scintillas will draw peak currents of over 60amps. Now you can see why blockbuster amplifiers of Krell current capacity are required for 1ohm working.’"

Cheers George

@h2oaudio

No reason to get elaborate. Too many words make misunderstandings even easier. :)

I'm just curious if you have measured the electrical frequency response of those amps hooked up to the Scintillas. I'd love to see those charts. :)

Best,

E

John,

Thanks for asking George that question as I forgot and really very puzzled as to where he got that from.

Henry

Hi Erik,

I will elaborate at a later time since I lost all 3 pages which I wrote, seriously. But very briefly, I am not asking you to believe anything I say of course! until you hear it. In fact, I don't want anyone to take anything I say as gospel actually.  I wish you can hear it in my system for yourself.  Even then, you might still disagree with me after hearing it, but that is just fine as different people hear different things in the same system and more importantly each listener might consider different aspect of the sound as more or less important. This is what I have alluded to previously when conversing with Kenny. Just so you know.

Hi George,  

"There is no way an Apogee Scintilla will sound anywhere near it's best driven by ANY class-d, and they could just switch off or blow up."

You SEEM  to be knowledgeable about audio but I am truly surprise at some of the statements you just made.  Actually, I have seen your same statement being made at some other discussion as well.  You seem to be all about theoretical stuffs.  So with your statement which I quoted above... So let me be a bit blunt here.  Have you ever own the 1 ohm Apogee Scintillas in the past?   Do you currently own them?  Have you designed an amp of your own design to drive them? Have you heard a class D amp driving the 1 ohm Scintillas?  Have you personally heard an H2O amp driving the 1 ohm Scintillas? and if you did, did the amp blow up? I have the scintillas for about 20+years now. and Yes I have designed amps specifically to drive them.  Conventional discrete transistors pure class A design that is.  Since you mentioned about the big krells, so how about 80watts pure class A amps dissipated 1000watts idle weight 200 pounds with over 1 Farad of  capacitance reserve.  Two 1KVA transformers for the output and twin 250 VA transformers for the front end and makes most Krell and Levinson amp look small. I wish I can post some pictures right here just to show you. Now I am not all about mine is bigger than yours but since you mentioned the Krell Master Reference amp.  Well, I am sure it can hack the 1 ohm Scintillas without sweat.  Krell amps are pretty good in my opinion and many still love them to this day. But then suggesting only those big Krell can drive the Scintillas properly and sound good?  Can drive it! I agree totally no questions! Sounding good? Well that is just a matter of opinion and that is your opinion which is perfect fine. And the same goes for my opinion.  And here is my opinion.  The H2O icepower based amps can put all these big krell and Levinson boat anchors and the likes into shame across the whole audio frequency spectrum.  Talk about dynamic, transparency, extension, Bass power and control, not sterile and one note or bloated bass mind you, midrange liquidity, imaging, staging, composure at loud listening level, subtleties and should I go on???  But remember this is only one man opinion which is mine.  Actually, I know a few Scintillas owners happen to agree.  But still, that is still not the majority.   And as for class D blowing up while driving the 1 ohm Scintillas, Well all I can say is NOPE!!! Not here at least for the 13 years or so while some the big SS boat anchors either blow up and/or going into thermal shutdowns. 

Henry

Noble100,
Tim,I'm so glad for you too hear that you have recovered that well.
I really love my job as well and I would greatly miss it if something happened like you have been through.

I really like hearing how you like your dsonics,I almost bought a pair a few months back,I had a very good conversation with Mr. Deacon over the phone.But a used pair of bel canto ref600m came up at a good price.I also wanted to try another ncore product without moving too the much more expensive 1200's.

Best of luck to you,
Kenny.

George,
I bet that combo sounds spectacular.

If I owned Martin logans either past or present,I don't think I would use a class d Amp of any kind,just my opinion.

I personally have gone a different direction,usually a person buys the speakers that they like and then pairs the right amp for them.I like my class d amps so much that I'm gonna find and pair the right speakers for them.Kinda unusual but that's me.

Kenny.

George,

Not only is it 1ohm @100hz, but it has a massive -90 degree phase shift at 100hz also, these two together mean almost a dead short as see by the amp. 

Where do you get your data on the Scintillas?  I owned a pair and measured the impedance magnitude and phase (scroll to the bottom):
http://www.lippaudio.com/apogee-scintilla/

No 90 deg phase shift at 100 Hz.  A very well behaved 1 ohm in that region.

- John

George,
If I’m not mistaken,do you still have a pair of BC ref600m.

No don’t own them, but of all the D’s I have heard they were the best, "BUT" only when they drove an expensive Raven ribbon tweeter’ed two way bookshelf. This Raven has a very benign flat 4-6 ohm load and not much -phase angle to contend with, the whole speaker was an easy drive.

If so what amps do you like better and what speakers do you use.

A pair of these ME1500’s the one for the esl panels in 100w class-A mode the other for the bass in 25w Class-A mode.
And highly modified bass Martin Logan Monolith III with the newer aluminium vapour deposited Neolith esl panels.
http://www.stereo.net.au/forums/topic/109666-reading-specs/?do=findComment&comment=1689719

I also loved the sound of these on a pair of Quad ESL57's, but you've only got 25watts.
http://www.audiocostruzioni.com/r_s/ampli/amplificatori-finali/mark-lvinson-ml2/mark-levinson-ml2.html  


Cheers George