joysjane At lower levels the music seemed to have lost weight/slam/punch. This loss was in the lower frequencies. As the volume went up the bottom seemed to increase but, the Kappa 9’s sounded anemic. After 2 minutes I get some very loud snaps coming out of my EMIT K & SEMIT K drivers on the left channel speaker.
I rest my case.
At 625W!! into 8 ohms, and 1225W!! into 4ohms and "said to be stable into 2ohms". They didn’t wattage clip, they have no drive into 2ohms.
It wouldn’t have mattered if these Kappas had the 3000w Behringer on them, same thing would have happened "no current, no 2ohm drive, no music".
They didn’t wattage clip or soft clip as atmasphere would have you believe, they just can’t handle the load and current that they were asked to give, and it’s what I’ve been saying all along.
Even a $199 1980’s NAD 3020 integrated "is stable into 2ohms", there’s more than just that, it needs to "almost double" or "greatly increase" it’s clipped" 4ohm wattage into 2ohms also (not just from 8ohms to 4ohms), and that why that spec need to be independently tested "if" ever given.
This is why a pair of old Mark Levinson ML2 monoblocks which are only 25w!!!! into 8ohms!! would have been able to drive these Kappa’s beautifully full range to a certain volume level, as they are only 25w, but they can close to double all the way down to 1ohm it’s said. 8ohm 25w 4ohm 50w 2ohm 100w 1ohm 200w
golfnutz Pretty much what I expected. Your experience is basically the same as my except I was using the IcePower 1200AS/2 modules (2.7 ohm rated) with Wilson Watt/Puppy’s. I believe you were using the 1200ASP modules (2 ohm rated). Not just the bass, but I noticed it in the midrange as well. It became very sterile to the point I couldn’t listen anymore. Stereophile also uses the word ’Anemic’
And the Wilson’s are over 92db efficient, but also have a nasty amplifier loading. Same happened to you as I posted above to the Kappa’s. And your 1200AS2 Class-D modules are said to be even better🤦♂️
Stereophile also uses the word ’Anemic’ to describe this behavior when an amp is under powered for a given pair of speakers - which I think is a good descriptive. I tried using subwoofers to ’fill-in’ more musicality, but it really didn’t help that much either.
This is classically what happens to "some" Class-D owners "with hard to drive speakers", that is to get a sub to give some more bass weight and to flesh out the lower/mids and mids more, but it doesn’t cure the problem fully
Buy a pair of pre-owned Merrill Veritas for $5K, they're stable down to 1 ohm. If you're unsure, just call Merrill and ask him if they'll drive the Kappa 9s.
As I said above, so is an 80’s NAD3020, stability is needed, but that is not the criteria for it to sound good at those types of speakers low impedance’s.It needs to be able to almost double it’s "full" rms wattage for each halving of impedance, from 8 to 4 and from 4 to 2ohms, and I asked Merrill twice, to supply that, and twice the question wasn’t answered.
just call Merrill and ask him if they’ll drive the Kappa 9s.
Ask him more so will they drive the Kappa’s to their very best, seeing they are very expensive amps. See if he’s a saint or a car-salesman.
'Stability' is that which prevents the amp from oscillating. Just so you know. So in the phrase:
As I said above, so is an 80’s NAD3020, stability is needed,
- the term is being misused. In fact its unclear what is meant here. Are you saying that the NAD goes into oscillation when presented with a 1 or 2 ohm load??
You are applying criteria that could be used as a measure of a Linear amplifier to a Class-D amplifier which can current limit cycle by cycle, hence the current limit and power limit of a Class-D amplifier can be decoupled rendering your statement irrelevant depending on the Class-D implementation.
It needs to be able to almost double it’s "full" rms wattage for each
halving of impedance, from 8 to 4 and from 4 to 2ohms, and I asked
Merrill twice, to supply that, and twice the question wasn’t answered.
OK, so what is the definition of instability for these Class-D amplifiers? Since they have over current protection mode, and soft clipping capabilities the amp continues to operate, but not optimally. Without the use of an LED display to the circuit board (1200AS2 has this option), how would you even know it’s happening - is bad sound is the only way? Again, since the amp is running and making music, would this indicate it’s stable?
dsper Back to the OP’s question What Class D amps will drive a 2 ohm load into his Thiel CS5’s
The proof is in the two posts done here, about Class-D and it’s ability to perform/drive "optimally" into hard loads full range, (not just to be stable!!) even with one of those speakers being very efficient at over 90db!!!
When are the Class-D spruikers going to stop trying to push them like they’re the total answer to amplification, and sell them for what they are, good for easy/medium loads and not hi-end "yet", like Agostino, Gryphon, Solution, Boulder ect ect for driving the types of speaker discussed here, and the topic of this thread!!!!!!!
You guys have me thinking. I’m not at all on your level of knowledge. So now is a good time for me to throw this out there. I have Legacy Focus mains, with Legacy Marquis center and a nice pair of Ascend Acoustics Sierra 2 raal surrounds. Couple of 18 inch subs also. We do up some video concerts while entertaining, classic rock mainly, and volumes stray up over 110 db ( at 10 feet ). The sound in that room is phenomenal. I had a new ATI Signature 6005 series amp, and occasionally the right channel would just quit. I called ATI. They were really nice about it and explained that probably the Legacy’s were dropping below 2 ohms and tripping the channel. ATI then called Legacy and found out that they indeed did go down to 3 during certain conditions. ATI replaced the board with one that could take more punishment, no questions ask. Here’s my question. Legacy has just released their "V" series amps. They are D series with Ice technology. It's double the output of my ATI. 600 verses 300 per channel . It sounds like a perfect fit to me. Any drawbacks ? Please don’t scold me on the effects of loud listening. I’m 64, been racing cars and enjoying loud hobbies my entire life. Too late to cradle myself now .. Thanks for any input.
Very nice speakers but sorry a b***h to drive, neither your amp (mosfet) or a class-D will suffice, they’re just not up to getting the very best out of these Legacy’s
That’s a pretty nasty looking impedance and -phase angle graph. Read back at amps I have suggested and you get the idea of what you need. Doesn’t have to be high wattage 50-100w will do, as those speakers are 95db, BUT!! you need gobs of current all the way down to 2ohms, look at what I say about "almost doubling wattage" for each halving of impedance, then go and search for amps that come close to doing this.
https://www.stereophile.com/images/archivesart/LEG20FIG1.jpg (fig.1) reveals that it needs to be used with an amplifier that can deliver high current into low impedances. Not only are there two minima in the bass of less than 2 ohms, and another of less than 3 ohms in the mid-treble, but there is an amplifier-crushing combination of 3.3 ohms magnitude and 60 degrees capacitive phase angle at 20Hz
@nitrobob - it would appear that V series amp is based on the IcePower 1200AS1/2 modules (not sure if it’s the 1, 2, or combination of both), which has a minimum impedance of 2.7 ohms. They also mention you should use a 20amp circuit for best results.
You might want to consider using a high current stereo amplifier for left and right channels only, and something different for the center, and surrounds.
OK, so what is the definition of instability for these Class-D amplifiers?
Stability is the same definition regardless of the kind of amplifier. It is the ability of the amplifier to resist oscillation. Oscillation has nothing to do with whether an amplifier can double power as impedance is halved, and has nothing to do with whether or any such nonsense. Its simply means the amplifier won't oscillate.
Now one thing that potentially could muddy the waters: it is possible to build a class D amplifier that is self-oscillating. This is done using the feedback loop with the intention of using the oscillation frequency in the encoding process of the amplifier. This is a handy technique as it also allows the amplifier to correct for phase shift in the audio passband. But such an amplifier could still be able to oscillate independently of its self-oscillation if there were a design bug! Confusing- but there it is.
Oscillation has nothing to do with whether an amplifier can double power as impedance is halved, and has nothing to do with whether or any such nonsense.
This statement is false, and quoting nobody, your inferring that someone said if an amp can double down to 2ohms, it’s also stable (won’t oscillate)
Can you point to who said this, or is this just a ******* in the wind statement that someone did, I’ve searched and no one has, not even golfnutz who you quoted.
Old Infinity speakers were tuned without much regard to impedance. I'm not sure which speakers you have, but I've seen a number of crossover upgrades for them you should consider which fixes these issues.
Good as they originally sounded, they were designed without the tools we have today which would allow for simultaneous optimization of frequency and impedance.
I've owned Kappa 9. X before and after mods to the XO. 10 plus years ago. I sold those speakers and the guy LOVES them. I did too, to tell the truth.
Ampzilla 2000 were the only amp that I owned at the time that would drive ANYTHING, including those.
They were touched by Mr B himself. I got them to actually drive .5-2.0 ohm strathearns ribbons. True amp killers at the time worse than Kappa 9. They were flawless, got hot but NEVER shut down. THE KEY was supply voltage for me. 20 amp circuit per amp.
The same when I sold them and went to class Ds. It was a supply and demand issue for me.
A single 15 or 20 for two monoblocks just couldn't provide the UMPH!! (mechanics term) without loosing the dynamics that Strathearns can provide. It took two dedicated circuits and voltage maint. of 120. The class Ds sounded stunning, even more so after a break in. How did I find out? The guy that bought the Kappa 9 went to class Ds at least a year before me. He almost got rid of them and he installed 2 dedicated 15 amp circuits from a single 15. He was amazed the difference in BASS response. From Krells to class D and once the electrical issue was ironed out, it sounded better than the Krells. ZERO floor noise, zip, nada, nothing... Goes to show that the amps PS is a big factor in how it performs. Krells, Big Macs, Pass, serious power supplies.
The class D sounded BETTER, than ANY amp I've used to drive True ribbons, or planars. As a matter of fact, the only place I run a different typology is in the mids and highs, that only with a GREAT valve amp (over 22K spec), and normally in the winter..700hz down nothing but class D. Just the best.. I use Nords One Up rev B,C,D NC500s x 7 and never a problem. Sparko and SI OpAmps.
I still have a shop full of great amps, and use them, sound great, but these class Ds are SO COOL....
One other thing, even VTLs that were sent back to the factory for the drop from 5.2 to 3.6 ohm, still didn't run the strathearns right. No valve amp at the time except Mcintosh MC275s in par or ser mode were 2 ohm stable, Mcintosh was! Crazy ay, old Mac, 2 ohm stable..I think even GG were too.
Mcintosh MC275s in par or ser mode were "2 ohm stable"
I've said it before, there is a massive difference in sound driving a speaker that's <2ohms correctly, and saying an amp is just "2ohm stable" and another that can drive down to 2ohms by almost doubling it's wattage down to it, and "remain stable doing it".
As I said before a $100 30w 1980's Nad 3020 integrated is also "2ohm stable" but sound like s**t into a 2ohm load, but hey! "it's 2ohm stable!!!"
As I said before a $100 30w 1980's Nad 3020 integrated is also "2ohm stable" but sound like s**t into a 2ohm load, but hey! "it's 2ohm stable!!!"
Cheers George
MC275 is a valve amp, no doubling..., most valve amps don't double, why? VTL, Mac, Cary Audio, Carver? why? I don't know why.
The wattage is the same at 8,4,2 ser or par. It didn't sound like like shi? same non ser or par. 16,8,4 either 75 wpc or 150 (186 act) ser or par. There is no doubling. It sounds good at 2 4 6 8 10 12 16, NO DOUBLING..Run warmer, yes, run hot yes, sound bad NO...Same with the class D, they may not double at 2 ohms but they sound, SOUND better than anything close in price. It was mentioned the THD was and is higher the tougher the load, BASS is not a problem. At 20% THD in the bass most people can't tell the difference..Even good ears, 3 out of a 100, might be able to hear 20 plus %. maybe..I'm at less than 5% using phase plugs, and basket termination. and class Ds.
I use to swear I'd never use a class D. Then I listened, with my ears, not my mouth, it's stereo then, not mono. I just shut up and learned, like a good mechanic, I learned.. Their, quieter, less expensive, 15 watt idle, lighter, cooler, VERY easy to work on, opAmp swaps a breeze, black background, ZERO floor noise. 1 ohm able 2 ohm stable, and no HYPER bright, blistering sonics like some amps. I don't care what's being used for speakers, if a class d Nord One up can't make it sound GREAT, move on. I bought Wyred 4 Sound and Nord, ICE, and Hypex.. Both have some neat features..Expansion wise
Mac says 2 ohm stable, it means STABLE, nothing more nothing less. It works there, not badly, not anything, but stable.. Nad is not 2 ohm stable it is 2 ohm ABLE, can hit a 2 ohm load, not trip a breaker, not sustained, just able to hit 2 and not blow up, blow fuses, the normal stuff from tough loads. Car audio .5 ohm stable loads. The size of the supply conductor, as I stated before, the key to low ohm loads. TIGHT connection, Very tight, required, not hand tight, wrench tight.. Increase the ability to deliver the AMPS, to the AMPS. Stable AC supply = stable amp...
So is a Nad 3020 integrated 2ohm stable, just means it won’t oscillate. Doesn’t mean it can drive that load to it’s fullest without breaking a sweat, same goes for the Mac.
The term 'stability' refers to the ability of a circuit to not oscillate. In the context as seen in this thread where it refers to doubling power as the load impedance is halved, it is being misused. IOW a circuit that is unstable is prone to oscillation; one that is stable won't oscillate.
Too many manufacturers here bend the truth and "con the readers" in their advertising into believing, that if they say their amps are "stable" into 2ohms, they can drive 2ohms loads easily, this is a "con" and needs to stop.
Like I said so many times now, a "stable" amp into 2ohm load means it won’t oscillate blow up and take out speaker drivers, but it does not mean it can drive the loads we are talking about here. If it did, then as I say once again, a Nad 3020 could drive the Sony SS AR1 talked about in another thread, or Wilson Alexia’s because "it’s also stable into 2ohms", which it has no chance of doing, and there are vary degrees of this, right up to big expensive amps
Look at unbiased tests and see if an amp can do it by looking at it’s wattage doubling performance into 8ohm, 4ohm then 2ohm and remain stable doing it, then you’ll know if it’s comfortable and able to drive 2ohms and "yawning while doing it". Many can double from 8 to 4ohms, but fall off a cliff when presented with 2ohms, these manufacturers usually only give 8 and 4ohm wattages hoping you’ll think it can do it into 2ohm as well, almost another con.
I have witnessed class D driving Thiel SC5 which belongs to a dear friend. And It has no problem of driving the Thiel at all and sounds fantastic. My friend own Krell FPB600. I also know a customer who has the Kappa 9 and he likes his class D more than his McCormack DNA amp. I personally own the Apogee 1 Ohm Scintillas and class D does wonder on these speakers. Hope that helps
I personally own the Apogee 1 Ohm Scintillas and class D does wonder on these speakers. Hope that helps
🤦♂️
I have witnessed class D driving Thiel CS5
And It has no problem of driving the Thiel at all and sounds fantastic.
My friend own Krell FPB600.
🤦♂️
36 posts nearly every one on Class-D amplification🤷♂️
You have been asked before by other members.
h2oaudio, welcome. A friendly note: the expected courtesy here is for those that are in the "business" regardless of how small an enterprise it may be, proclaim that each time they post. This is especially true if they're listed as a "private user".
I thought it was clear that I am a manufacturer. My apology to the OP if that was not clear. I am not sure why I am not listed as a manufacturer as Audiogon knows that I am a manufacturer as I have registered as a manufacturer.
Like I said so many times now, a "stable" amp into 2ohm load means it won’t oscillate blow up and take out speaker drivers, but it does not mean it can drive the loads we are talking about here.
Ok 550 watts not oscillating, won't drive a speaker correctly? Wow, never heard of such a thing. 550 watts at 2 ohms is 550 watts at 2 ohms. It gives a time it will hold that 550 watts too. Mac says STABLE, it mean stable and ABLE.. Not just able for a second or two. You keep saying what you mean, NOT what the manufacture mean. Stable is stable.. I'm sure some of the claims of amp manufactures is bogus, but the class D Hypex and ICE amp specs have withstood the test of time for many many years now. not a lot of problems.
Thiel
dontnwaste time w D
get class A/AB for best sound
w D 40?
I can figure it out, proof your stuff mate.
Thiel is not a problem, they will sound wonderful, NC400, 500, or 1200 all will drive them..The two latter have buffer board options..
Class Ds with Sparkos or SI are class a opamps, LEARN, before you speak..That type of stuff just isn't talked about. CLASS A. That is the reason the upgraded buffer boards make such a difference in Class Ds, Upgraded voltage regulators and class a opamps, night and day.
All the class Ds I use will drive the loads correctly..Simple. They all require GREAT VAC to get there. Hypex an ICE both require a good source of VAC, via the spec sheet. They both give specs at 100, 110 120 volt. As I said. The supply is the key to any heavy load. VERY tight connection and 120 VDC, class Ds will hold their own with any of the big names, at many times the cost. I own Pass, ML, and Krell currently. For SS I'll take the Nords, Pass is as good if not better, but they cost.... 3 times and will never run as COOL...Sure like the sound, though, in the winter, krells will heat the whole house, and very expensive to work on.
Tell you what, you suggest an amp at 1000.00 USD New. It has to have just half the specs of the hypex or ice modules. 1000.00 USD New? Class A, AB, anything that sound as good, stays cool, low cost to run, quiet, and 1/2 the wpc, heck a 1/3, a 1/4. Now let's add, able to change the sonic signature, in 15 min, all over the map.. Now lets add can carry 2000 watts under each arm..
Everything I read, where you point to someone's quote, the article are single quotes, from a single source, and a single opinion, or 1989 speaker adds about how they still make it.. SO!!!
So they still make a poorly designed XO, heck I can do that.. Really I can screw up, make a mess, and say it's still a great product. Even if it's NOT...
Is there a reason? I think you got a house FULL of class Ds, are you a class D junkie on the down low.. Joined the A/AB club and it's blood in and blood out? 1% amp gang or something..
Class A-Z amps are the bomb What happened to Ds I like double Ds, a pair. WHY AREN'T Class D amps the bomb?
Like I said so many times now, a "stable" amp into 2ohm load means it
won’t oscillate blow up and take out speaker drivers, but it does not
mean it can drive the loads we are talking about here.
Yes.
'Stability' only refers to oscillation or the lack thereof. It says nothing about low impedances, unless the amp oscillates when presented with a low impedance.
What's wrong with Behringer? I use a pair of their 12Ks and a pair of 2496 active XOs and they WILL drive ANY load. I use them for 40-400hz . I've never listen to them other than bass duty.. Flawless.. I've used them for sub duty also 40-60 or less.. They can move a lot of air... a whole lot...Very Very low distortion.... No noise, I love um.. Their not a Nord, but sure work... I'm gonna add a fan switch, off / on for low low listening, other than fan noise...The 12ks are great..27 lbs...
A class D amp can do 2 ohms if the intention is there on the account of the designer. Several things have to be present to really make this so.
* the amplifier must have sufficient current handling ability in the output transistors and power supply * the amplifier must have sufficient heatsinks as they will run hotter driving 2 ohms * because of the output filter considerations, the amp should be self-oscillating. In this way it is possible to run enough feedback to allow it to correct for phase shift otherwise imposed by the filter.
Thank you, atmosphere, for your numerous interesting and very informative posts. Class D Hypex and UcD power module designer, Bruno Putzeys, has stated that there's no such thing as too much feedback and that he's able to make a class D amp sound however he likes but decided his goal would be accuracy. Here are a couple interviews with Bruno Putzey about class D I thought members on this thread might find interesting, relevant and informative:
@noble100 Yes, Bruno has been able to design class D amps with loop gain north of 75dB!!
He did acknowledge to us that there was a typo in one of his papers when we pointed out a math error regarding the oscillation criteria. It was not an error in the paper itself though, it really was a genuine typo. Brilliant guy.
Bel Canto e1X, stable into 2 ohms. See recent Stereophile review.
Like I said, "stable into 2ohms" is a smoke screen furphy, to make the gullible feel it can happily drive 2ohms without strain, it just means it won’t oscillate and blow up, as Ralph also said two of his post back. So is a 1980’s 30w Nad-3020 stable into a "2ohm load", but there’s no way in the world it can drive it without any strain, if it could you would see the 4ohm wattage almost double into 2ohms, but that’s not given with the BC for a hidden reason.
Even the Stereophile tests show the eX1 can’t even get close to doubling from 8ohm to 4ohm!!!, let alone the 2ohm, it for sure would have gone backwards, instead of up if it was given.
The output impedance of almost any class D amp is so low that doubling power as impedance is halved is no problem, even into 2 ohms.
The limitations are current capacity in the output section, current capacity in the power supply, heatsink capacity and finally issues surrounding the output filter. Its likely that the latter will be most problematic, which is why self-oscillating is attractive since it will allow the amp to correct for phase shift induced by the filter. Getting output devices that can handle the current is academic at that point- its all about how far you want to push it in the design- you face most of the same constraints you do with a class AB amp.
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