You’ve got one of the greats in those Thiel CS5’s dsper, but are seriously hard to drive.
The OP has asked which Class-D can "DRIVE" a 2ohm load, not one that won’t occillate or blow up into a 2ohm load, and not be able to drive it fully.
I’ve seen no Class-D independently tested, be able to come close to doubling it’s 4ohm wattage when presented with 2ohms, and remaining stable and comfortable doing so.
This is a true test of being a great amp that can handle and "DRIVE" speaker loads such as Wilsons ect can present down to below 1ohm, including your Thiel CS5’s, they can go down to .5ohm at 20hz and remain at 2ohms still at 50hz!, and are still under 3ohms all the way up to 200hz!!!
None of the Class-D’s mentioned here will do these great speakers justice at all, the ones suggesting so are all tripping!.
Yeah your speakers are one of the greats but need a equally great amp to do them justice, especially in the bass.
Those here that say x class-d can, can not show independent test resuts that show the 8ohm wattage doubling to 4ohms and then the most important one almost doubling again from 4ohms down to 2ohms.
This is the true test to see if an amp is able to "drive" properly into 2ohms and in your case .5ohms, and not just make some noise into it.
DESPER a pair of John Curl designed Parasound Halo JC1 monoblocks will do the job nicely, and not cost much used.
Speakers like these Thiel CS5's, their bigger bother the CS7's, all Wilson Watt/Puppy, Alexia's mkI an mkII, also the Alex, Max ect ect ect and many other brands, have sound to behold when "driven" with amps that can do current, that can keep doubling the full output wattage for each halving of impeadance loading, and to say this type of speaker doesn't make sense, shows high degree of ignorance, bad hearing or never heard them "driven" properly.
The reason you are putting **** on this type of speaker, is that class-d won't drive them to their maximum sound quality. These types of speakers are engineered to be far closer to having ideal test mearsurements and sound perfection than easy to drive speakers, that are far more comprimised.
You guys are just p***ing against the wind quoting big watts, and not quoting the wattage for each halving of impedance at 8, 4, and 2ohms
It’s not about the big watts, Class-D P.A. amps like Crown ect can do that. It’s about the amp being able to come close to doubling it wattage for every halving of impeadance 8, 4, and 2ohms!
The classic massive Mark Levinson ML2 mono blocks at only 25w into 8ohms will sound better into into these speakers than any 10,000w Class-D, because it can double it’s 8ohm wattage all the way down to 1ohm ( 25w 50w 100w 200w). Which means it can "DRIVE" these speakers
Granted it won’t do party levels because after all it’s still only 25w at 8ohms , but it will p**s all over your ice power class-d for sound quality, into these types of speakers.
And my IceEdge modules
And there is is! the plug yet again.
1200 watts into 4 ohms and 1000watts into 2ohms
And there it is, s***'s itself, can't deliver into 2ohms
Anyone know why Thiel designed such hard to drive speakers
Not just Thiel, there's many others that strive for perfection and they're usually the most expensive.
Xovers/drivers ect, are complicated to get everything to operate in the most linear function and best specifications without having many compromises, that most efficient speakers tend to over look for the sake of efficiency.
That's why you need great amps usually with great speakers otherwise you don't get what's the speakers capable of giving you, if not you compromise the speakers performance.
I'd say to the OP, contact Nord directly and run your thoughts by them. I'm pretty sure the last thing Colin will want to do is sell an amp that turns out to be useless!
Now your twisting things by saying "useless".
Of course it will "work" and he will say so, but will it get the very best out of the speakers?, DEFINITELY NOT! especially in the bass where they are a pig of a load.
I have a Classe Class D Sigma Amp 2 driving Wilson's which I am told dip down to 2 ohms. They sound GREAT.
Not saying they don't, but if you have Wilsons that go to 2ohms (your not saying what ones) then your not hearing them at the their best. And you maybe happy with that, because you don't know better.
Then why did you say "useless"
Of course it will work, class-D just won’t get the best from these speakers especially in the bass, and some maybe happy with that not knowing any better.
But I think if anyone had a speaker that was regarded as Stereophile "Class A" in the "full range" category, and one of Thiel’s all time master pieces, you would like to get the best out of it.
Stereophile JA " All in all, the CS5 is both the most thoroughly worked-out speaker design I have ever come across and perhaps the best-measuring loudspeaker I have yet experienced."
The Manley 500s, which I held off hooking up for a long
time, were, as nearly as I could determine, simply unable to deal with the CS5's cruel 2 ohm impedance at the low end."
The Manly 500 watt monoblocks https://images.reverb.com/image/upload/s--i_Cjxmnb--/f_auto,t_supersize/v1552409073/zucn7la3dmcwphn2...
I’m not going to get further involved as, for me, hi-fi is about the music more than the equipment although the latter isn’t without interest.
Now that reeks of a copout.
I also don’t pretend to have the level of knowledge evidently demonstrated by numerous contributors to these forums.
Yet your not willing to take it onboard when it's presented to you in simple terms that anyone can understand.
Kudos to Joseph Audio for going the other way, and actually adding crossover components
That’s just adding series resistance to the perceived load to make it look higher to the amps output stage so it doesn’t complain, and what that does is lower the damping factor and raise the output impedance as seen by the amp
You get a similar effect by using a ZERO output transformer with amps that aren’t right, and we all know know that is just a band aid fix, better off having the right amp to start with.
last thing Colin will want to do is sell an amp that turns out to be useless!
I never insinuated Class-d's would be "useless", I said Class-D's into these types of speaker loads won't get the very best out of them, end of story.
They will drive 2 ohm speakers with ease and aplomb all with a very satisfying sound quality.
Looks like there’s still no takers willing to put it on the line, and post up the 8ohm, 4ohm, 2ohm wattage measurements just before clipping, to see if they are "almost" doubling the wattage for each halving of load, so to prove if their amp/s are going to drive these types of speakers close to their best, not just "satisfactorily"!
There's no mention of power doubling down all the way down to 2 ohms but an amp that is completely indifferent to actual speaker impedance variations seems promising, right?
That's because it can't, here is the a snippet from the manufacturer's data sheet, which you can take with a grain of salt normally, independant would be even more revealing usually.
As you can see at 1% distortion!! the 2ohm watts didn't double at all from 4ohm, the 8ohm to 4ohm came close to doubling though. And that little 1 next to 450w said went into current limiting on 2ohm.https://ibb.co/YcQ8xV7
tell us which proven amps specifically you are recommending dsper consider buying?
As I posted just ones that can almost double their clipping wattage from 8 to 4 to 2ohms. Even the ML2 monoblocks at only 25w into 8ohms will do it, but not at party levels, because they can double down to 200w at 1ohm.
All we have here are a few manufacturers spruiking their new or yet to be released Class-D amps without any shame, saying they "can handle" the 2ohm load, making out they can drive this speaker to it’s best in the bass. Without presenting any measured proof of their claims, that they can almost double their clipping wattage from 8 to 4 to 2ohms.
Our prototypes can double power into 2 ohms and we’re not even trying to make it do that. It comes with the territory.
+10 atmasphere for putting that one to rest.
Nothings been put to rest, let’s see the independant test or even his own, that show the rms wattage doubling just before clipping (same distortion) with all three 8, 4, and 2ohm loads, then I’ll eat my words, and congratulate you on doing something that other Class-D’s can’t. I’ve asked the same from Merrill twice now and got no answer.
And btw, I’ve never claimed the new GaN Technoglogy could drive these speakers properly and double at all 8 to 4 to 2ohms loads either, they just sound better than the old technology, but I wouldn’t recommend them here either.
find yourself a brute linear amp/s with BJT (bi-polar) output stage, with high bias Class-A used somewhere to get the best from your highly regarded speakers.
Do not get sucked into by these Class-D spruikers because you won’t get the best from your speakers.
Or (I wouldn’t) sell your speakers and get something easier to drive that doesn’t reach down to sub 2ohm loads in the frequency range, then you can by a GaN based Class-D which will sound very good.
and can handle speaker impedance loads under 2 ohms, dsper
That statement it’s should tell you something, they "can handle" a 2ohm load.
My car "can handle" being reved to 8,000 rpm. My hands "can handle" 60c on a Class-A heat sink for a few seconds!
Your speakers are at 1-2ohms for nearly 3 octaves in the bass
"JA which means that the amplifier with which it is used must have ample—to say the least—current capability if the sound is not to become anemic."
Like I said above " find yourself a Krell type ect linear amp/s with BJT (bi-polar) output stage, with high bias Class-A used somewhere to get the best from your highly regarded speakers."
Read these amps that were tried and you’ll get an idea of what’s needed to get the best from your speakers.
" The best one I heard was the Krell KSA-250 (their latest product—though by the time you read this there will be a KMA-600), followed not too far in second place by the older Krell KSA-200.
The newly arrived Threshold SA/12 monos had plenty of overall power, but lacked the drive at the low end possessed in such quantity by both Krells, and had a refined, neutral upper range that seemed to leave the Thiels lacking in sparkle.
Until now, my favorite overall amplifier has been the Mark Levinson No.20.5, but it simply didn’t have the low-end punch necessary to bring the CS5 to life"
Spectron Musician III mk2 mono blocks - I believe they will provide around 300 watts at 1 ohm - or it might be at 0.5 ohm -
Once again this means nothing, give us the clipped wattage at 8ohm 4ohm and 2ohm and 1ohm, only then will you know if it's being current starved (sagging).
why can't discussions of audio stuff, hifi stuff and music listening stuff, be non confrontational ?
really you have to ask this?? Because there's way too much BS and Voodoo in hi-end audio Mr D
What I’ve learned lately on this thread is to avoid using speakers that present loads to the amp of less than 2 ohms.
What can be the case, is these speakers can be the best measured/sounding ones, why drive them with amps that can’t do them justice.
As for flipping the bird to amp manufacturers, only when it’s warranted because of not saying how it is, or recommenders of them that have no idea what they’re on about.
Because they the manufacturers/recommenders would have "you" believe if an amp with 800w can drive a speaker that’s "inefficient" and with a "average impedance loading". Then that same amp can also drive a speakers that are "even more efficient" but with a "very hard impedance loading".
it does not double the power when halving the impedance - but it is apparently stable at 2 ohm
No it’s "not bad" for a class-D, nowhere near doubling still, at least it goes up as the impedance goes down, too many either don’t go up at all at 2ohms or go backwards. "Could" be ok for the OP’s speakers if it's to be believed, and "may" get the best out of the low impedance bass they have.
600 Watts at 8 Ohms
800 Watts at 4 Ohms
1400 Watts at 2 Ohms
It will be interesting to see with independent tests if they give it to someone like Stereophile, if they have "underquoted the 8ohm and 4ohm" to make the 2ohm look as good as it is. As many manufacturers are doing that now, that you can see that on Stereophiles bench tests, it one way of making the amp look to be doubling, and it’s wrong (lying) and should be stamped out.
Sorry - the specs above are for stereo single amp - the power is considerably more in mono block configuration
If these are bridged stereo’s into mono’s? (probably as they give no specs) if so they won’t even do as good as the stereo amp in doubling down.
I have driven my 1 ohm Scintilla’s with the NC400 mono blocks from hypex.I use them sometimes in the summer months when it gets to warm for my Krell KRS100 mono blocks
My friend also has the Scintilla’s, what a great speaker when driven right.
With this https://ibb.co/mSV04BPhttps://ibb.co/m6LhhPc
1st post, bet you can’t wait for winter, otherwise you wouldn’t still own the Krells. It must be because they sound and drive the Apogee’s better by quite a margin, otherwise you would get rid of them?
Also there are cooler running Krells, that would sound almost as good as the 100 mono’s, and still blow away the NC’s on these great speakers..
Theta Digital Prometheus -
8 ohm - 250 W
4 ohm - 500 W
2 ohm - 850 W
Yes another one beside the Spectron (which is yet to be independently tested) that "can" get the watts up into 2ohms, but this is at a cost.
JA’s Note: " However, the distortion rises considerably into 2 ohms"
BTW: Note! Both use Linear power supplies that’s why they’re big/heavy for a Class-D >20kg. No smp power supplies here, that’s a good thing.
At 10Hz it is approximately .6 ohms.
That when the vinyl warp frequency will tax an amp, or even a bit of dc servo flutter when the mains chucks a slight wobbly.
It's been reported that Jim Thiel ended up using Krell 600 Watt'ers.
Correct type of amp, that will almost double down to 2ohms without breaking a sweat, though the 250 or even 150 watt'ers would do, they all can do the Krell doubling act.
There are many other brands that do the Krell doubling act also, all use Bi-Polar (bjt) output transistors, just like the Krells.
We all know George will be first in line.
Having a dig are we? well at least you’ve got that one right sunshine. I’ve never been against Class-D, just it’s two Achilles Heels I have a big problem with, switching frequency and dead time. Which gives it that " Plate glass transparency" that you call it, I call it "sterility" and missing harmonic decay.
I’ve always said, ever since I started the the debate about the new GaN technology here way back, that when the GaN Class-D amp becomes affordable to me, with what Technics has done with the SE-R1 with using 1.5mhz switching speed, I’ll be the first in line to get one, and ditch my inefficient hot boat anchors, door stops if you don’t live by the sea.
he’s able to make them reasonably priced since I get the feeling I’m going to be a future customer.
Judging by his offsider Tweak1 by another maker here, that’s going to cost you far bigger than it should. https://forum.audiogon.com/discussions/which-class-d-amplifier-ps-audio-ghent-nord-merrill-or-other/...
the Bryston 14BSST would go into protection mode from overheating due to the impedance.
With these sorts of speakers like the CS5 ect it’s no wonder, these tested figures show it was definitely no current master into low impedances
8ohm load 690w
4ohm load a reasonable 1000w
2ohm load it barely got off the 8ohm mark at 720w, very sad.
I did see this:
Output Power, Short Term
8ohm, 1% distortion = 227 watts
4ohm, 1% distortion = 450 watts
2ohm, 1% distortion = 450 watts with a footnote stating "Power is limited by overcurrent protection system (OCP) and highly dependent on thermal conditions."
Not sure what the footnote means.
Amps goes self into destruct mode if current limiting doesn’t work, no other reason for it to be limited, unless purposely done to sound bad into those low loads?
Purifi 1ET400A has no buffer, so it is expected to a manufacturer to add a custom buffer, and add more gain as needed.
It also has a disappointedly low 2.2k input impedance, so the use of most capacitor coupled (unless >10uf) preamps, tubes, or solid state or passive preamps direct in are out of the question if no extra gain is needed, which with today’s sources giving so much higher output, no extra gain is needed, so then neither would be an opamp buffer.
And if more gain is needed then a direct coupled opamp smd buffer is the only obvious option, again not capacitor coupled, solid state or tube buffer otherwise a massive 10uf coupling cap will be needed into that 2.2k input impedance.
WHY!! they keep making low input impedance amps these days is beyond me, go back to 48k (the once recognized industry standard) or even 100k like it used to be with tubes, makes for a whole better range of preamps ,tubes SS or passive able to drive them properly.
Custom buffer adds gain and increases impedance to 47k ohms.
There’s no need for it in many cases, as sources and preamp have enough gain these days. It’s just "another opamp in the signal path" that’s not needed in many cases if the input was high enough instead of 2.2k, who wants that in hi-end if it can be taken out and one less opamp yay!!! gotta be good for the sound, and the business.
I think that’s a very legit observation or "complaint" as you would put it..
Seems like this could be the module your using, as you've turned up the force shields a notch higher on this one, if so just go with the buffer by-pass switch.
Our preamps can drive such low input impedances-
Of course it can, how did I know that was coming, stick with tubes, your good at it, and built your rep on them.
The fact is this amp without buffer it has around 15db of gain around the same as the Nelson Pass First Watt F5 and with today’s high output sources and preamps, in most cases you don’t need another soul destroying opamp buffer in the signal path with or without gain.
Here is the comments from a manufacturer of these Purifi’s Class-D amps when I queried him on the unnecessary low 2.2k input impedance. I think it could be because of the use of bjt input stage instead of fet, I’ve yet to suss that one out.
Yes you are absolutely correct that you can use a high output DAC directly into this module. "That would be the ultimate solution"
And I am considering a buffer bypass mode. However most power amps will have gain in the region of 26dB to account for sources down to 2 Vrms. A typical DAC straight in is a good solution with digital volume
Most digital sources today have far more than 2v and owners preamps can certainly have enough for the Purifi without another buffer.
As Nelson Pass with his F5 said " If you need to turn the gain up on your preamp, then do so."
Sorry but what you get is a good PA amp.
Hypex suck in, they purposely put things backwards to confuse at glance. Look again, and that’s peak watts and amps, also the wattage go backwards as the impedance goes down, it gets severly current starved.
Nowhere in this universe can this thing come close to doubling into 2ohms The NC400 of theirs is a far better module as far as current delivery into low impedances it actually goes up in watts instead of down. Data sheet download here https://www.stereo.net.au/forums/applications/core/interface/file/attachment.php?id=480207
I emailed, to both Nord and Appollon, the Stereophile measurements for the Thiel CS5’s and both suppliers said that their amps would drive them.
(Without seeing any independent tests)
Of course they did, they want a sale.
No one disputes that they can’t drive the Thiel CS5’s to a point, just if they don’t try to double from 8 to 4 to 2ohm, you won’t get the very best out of them, they will be compromised in the bass, if you don’t mind that that go ahead.
But not if you drove them with amps like the ones I have described, that can come close to doubling wattage all the way, from 8, 4, and 2ohms, I believe the Thiel’s are worth the right amp to make them sing top to bottom, don’t you?? it’s up to you.
what’s wrong with efficient easy to drive horns?
If you need to ask that, you should delve into the measurements of both a bit
To have that efficiency and easy load ability. Measurement tests show they are always compromised when compared to a highly tuned speaker eg Wilsons ect ect, that will be far more inefficient and much harder load, that yes need far more serious drive characteristics from the amp/s
Bit like comparing a high octane highly tuned multi cam/valve Ferrari V8 motor, to a low octane V8 Ford iron slug from the 60’s.
George, the quote above suggests that you do not understand how a voltage source works
Yes you use this old chestnut everytime as it suits you to bring it out every time your OTL’s are brought into question doing the same thing.
So it’s simple for all, instead of doing war and peace to confuse everyone as he usually does. dsper OP
here’s is the proof, Thiels CS5 that have impedances that reach down to below 2ohms will get "driven" and sound far better "up to a given level" with the 25w!!! Mark Leveinson ML2 monoblocks, but certainly not louder than 1000w, 2000w or even 3000 watt Class-D amps, because the ML2’s can do the doubling act into lower impedances right down to 1ohm
Put the shields up Scotty, we’re being attacked save the Enterprise at all costs.
On these OP’s speakers with the minuscule 25w ML2 monoblocks will do bass and everything better to a given level, than any Class-D can, and that’s because of the current it can keep supplying down to 1ohm
I did unfollow, but I got this one before. definitely gone now.
Look at complimentary BJT’s with massive power supplies that I’ve been suggesting for these loads, then look at your Class-D Mosfets usually not complementary as the P channel stinks, then the 8th grade maths don’t mean ****..
George’s arguments are irrational. For him doubling down power is more important that the absolute power and current the amplifier actually gives.
Sorry but this is wrong, have you ever listened to a pair 25w Mark Levinson ML2’s on a pair of hard to drive speaker like the OP’s? "to a given level" (because they are only 25w after all) they will annihilate any 500w or 1000w Class-D.
This proves that doubling down (current) to below 2ohms into this kind of speaker load is the most important factor for sound quality, not wattage!. ( otherwise we would all own $400 3000W! Behringer NX3000 Class-D’s )
Although if you want to go louder then wattage becomes a factor also, so then the same kind of amp that can double with more watts is needed then.
So you my friend are the irrational one not me.
BTW You’ll never see a pair of ML2’s for sale used as owners die with them!
1. Get a Class D amp.
2. Find some Kappa 9’s.
3. Set the the switch in the rear to Extended.
4. Crank up the music.
5. The Class D amp that doesn’t shut down will drive a 2 ohm load.
I can say this after completion of the above five steps,
This is gonna be one very short list of Class D amps
Crude way, but effective.
Better to just see how they behave in tests not understated into 8,4, and 2ohm and see if they can do "close" to the doubling act for each halving of the impedance.
My answer to the posted question,
Stay away from Class D amps to drive low impedance speakers.
Many manufacturers just under specify the 8ohm rating to allow their product to be in spec for the lower loads.
Yes this must be observed, as many "cheat" by understanding the 8ohm or the 4ohm watts, just so the 2ohm look better.
If all above is not taken on board, just buy a 3000!watt Class-D for just $400 and see how you go. https://www.storedj.com.au/behringer-nx3000-ultra-lightweight-3000w-class-d-power-amplifier
That’s right, it doesn’t matter how many watts you have, if you don’t have the current to back it up all the way down into 2ohms and less, with speakers like the OP has in the bass, you got s**t.
Like I said the "puny" 25w Mark Levinson ML2 monoblocks will slay them "to a given volume level"
Are you serious! You buy it and drive the Op’s speakers then
You are really in a world of denial. if you think this Class-D can out drive the 25w ML2’s "to a given level into these OP’s speakers."
I’ll lay money on it also that those watts are not real or RMS, would be nice to see some independent test, at 8,4,and 2ohms
You buy it and live with it, because you obviously think 3000w can sound better than 25w into the OP’s extremely hard to drive speakers.
It’s like saying a 1/4mile dragster with 8000hp can get to the top of Pikes Peak hill climb faster than a 100hp rally car, delusional is the only word, even the most technically inept on these forums would think so.
design your own amp, send it to me
You just need to search buddy, I’ve built some of the biggest pure class-A solid state that were water cooled, one that was a three man lift, explained in great detail in Audiogon and other forum pages if you could be bothered looking.!!
This is what I use at present https://ibb.co/zNMMnpThttps://ibb.co/8XqKvJd
find out whether the phase shift has any relevance in your listening.
If you believe there nothing to hear when you have 70 degrees phase shift at 5khz and still 50 degrees at 2khz!! then there’s no hope for you. https://ibb.co/JdrgGBH
I have heard class D amps that sound euphonic/rolled off in HF, and others that sound harsh.
All because of the setting of the switching frequency output filter and where it acts, either "too high" or "too low"
"rolled off in HF" (too low) , and "others that sound harsh" (too high), with today’s 500khz switching frequency.
Raise that switching frequency 3 x to 1.5mhz as you can with GaN, and you’ve got rid of the problem because the output filter can then also be raised 3 x higher, and then you don’t get that phase shift so low down into the audio band or the problem of as you say ("rolled off in HF, and others that sound harsh"), because the filter then can be set to do it’s job fully and rid the switching frequency completely and not effect the audio band with phase shift.
It’s that simple, even the most technically inept should be able to understand, maybe! Or you can believe the ones that are trying to tell you it doesn’t matter. From day one Class-D has had this problem, because of it’s low switching frequency/filter.
Well you have just made yourself look like a total ?
Read again and take it in, I didn’t say I built Peter’s amps who is a long time mate, and not at all in a good way.
I said it’s what I’m using at the moment, mcreyn
get a life, really!!!
Your defiantly not worth the time or effort, I said search and you find out.
And you believe all he says, I believe my own findings and an Electronic Institute before any manufacture spruiking and trying to make a buck.
Once again here is one main difference why a Class-D with Mosfet will not drive into a hard speakers load like the OP’s Thiel CS5’s like a good linear amp like the ones I have suggested with BJT (bi-polar) output stage.
And Class-D’s don’t come in BJT
Electronics Foundations: Semiconductor Devices
[Lecturer] BJTs tend to have better, more linear gain characteristics…and can give you a lot higher voltage gain than MOSFETs.…They’re also able to handle higher output currents…and have a lower output impedance.…That gives BJTs a huge advantage over MOSFETs…for building amplifier circuits…that need to provide a significant amount of output power…and or drive loads that have low input impedance.…MOSFETs are going to have a harder time…driving a low impedance load…because they have a higher output impedance.…