It would seem many here hold their own share of beliefs and agendas either in favor of or against Class-D for a variety of reasons - certainly predictable and all too common to have some sort of investment in a particular design principle, sometimes based more in theorizing than drawn from actual listening sessions.
Perhaps in an effort to counterbalance my own inexperience and skepticism, or even prejudice against Class-D designs in regards to successful implementation with very high efficiency loudspeakers (+100dB’s), does anyone here have practical experience in this regard and how this combo plays out? Typical "wisdom" seems to have it that Class-D designs are less favorable within the first watt of usage compared to Class-A designs - not least SET’s/SIT’s - and are therefore considered the poorer match with very high efficiency speakers. Is there any merit to this in the eyes (ears) among those with actual experience here, or is it a field laden predominantly with theory as to how things ’should’ (as opposed to how that actually ’do’) pan out?
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Hi Phusis,
Not sure why high efficiency would be a bad combo. The issue with different Class D designs, as covered, has more to do (in my mind) with impedance drops of exotics.
They are dead quiet.
When I first heard digital amplifiers it was with a pro monitors based on pioneer metal-dome compression drivers. OMG that was painful. :)
But that was in the 80's.
Class D amps are also dead quiet, so that's not a big deal.
Still, I don't have recent experience, so I hope some one who does will chime in.
Best,
E
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@kdude66
No worries at all. :) I think that the participation of so many here who have been pleasantly surprised and are enjoying Class D amps speaks for itself.
We also went a little deep into theory without measurement. :-) We should stay away from that. My bad.
Best,
E
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I can easily comment a little about the pairing of class d with efficient speakers.I have been using d with Zu definitions for 4'yrs and also a pair of Crites cornscalas that I built for 2 yrs.Basically if the first watt of any amp is no good I don't want x amount more of them.There has been a lot of people say that high damping factor of any class of Amp is'nt a good match too full range drivers which cause over damping of the cones and don't sound as natural in a musical note decay.I found this not true too my ears,I have owned lots of tube and class a amps over my time and my preference in the music presentation leads me back too the class d amps I currently own.I had a pair of the Janzen Valentina hybrid ESL speakers recently for 6 months and drove them with class d very well.But I like the Zu's better in my room and kept them.I have a pair of Tekton double impacts that will arrive this wed and I will see how they sound with class d.
The only negatives to class d is driving the exotic speakers,the ones that drop below 3ohms.
Reproducing audio in the home has and will always be highly subjective and system synergy has tremendous benefits.
Erik,
I'm not a Amp designer but I have been a Avionics tech at a major airline for 28 yrs,so I have a fair understanding of electronics in general.It is very cool and also very interesting too learn as much as we can about our gear but you are going to hurt your head just like I have trying to fully grasp class d.I prefer to just kick back and enjoy the music.I recently caught myself analyzing my double impact speakers before I even get them,crossover points and driver configuration.There is a lot of positives for class d now and in the future.
Kenny. |
Class-D that can finally equal or better hi-end linear amplifiers, tube or S/S. It's closer than you think.
Why We'll Soon Be Living In A Class D World
"In fact, that transistor technology is available today and is increasingly being used by manufacturers to create near perfect sound quality for Class D audio systems. The greater switching speed of Efficient Power Conversion's (EPC's) eGaN® FETs allow amplifier designers to increase PWM switching frequencies, reduce dead-time, and drastically reduce feedback; in turn, producing a sound quality previously limited to large, complex, heavy Class A amplifier systems. Further, this innovative high-speed switching technology has already disrupted myriad other industries, including telecommunications, medical, and automotive to name a few.
A high-definition eGaN FET-based system with higher PWM switching frequency, reduced feedback, and higher bandwidth produces the sound that has the warmth and sonic quality that audiophiles demand; while actually improving upon the power efficiency of traditional Class D. Class A audio's historic lesser child Class D is coming of age with eGaN technology. And in the next decade, these systems will replace Class A technology, as well as the silicon MOSFET Class D systems in active use today.
Significantly, audio manufacturers are taking notice and incorporating GaN-based Class D FETs in their systems. This is why, in another two or three years you will start seeing a slew of new Class D amps - ones based on GaN - rolling out to the market;
and, for such varied uses as home theatre, car, boat, portable wireless speakers, along with high-fidelity home systems."
Cheers George |
George,
Right on track,I love it.
I was eventually going to post this info but you beat me too it.
Kenny.
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My own take on high efficiency speakers and flea tube amps:
People LIKE the sloppiness.
That is, the high impedance outputs of the amps make the electrical frequency response much more variable, and .... that's what some people like. :)
I don't think it's from "damping" or over-controlling the drivers at all. But hey, no matter. Buy what you like.
Best,
E
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"The only negatives to class d is driving the exotic speakers,the ones that drop below 3ohms."
Kenny,
I believe it is all about system synergy and listener's preferences. I have class D driving the Apogee Scintillas just fine. The Scintillas's impedance is 0,8 ohms from 20Hz to about 2 KHz, and about 2ohms from there on up to 20KHz.
Henry
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I would think your not using a ncore 400 or 500 to do that.
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Offcourse it has always been about synergy and preferences,that should be a given.
Kenny. |
@h2oaudio
VERY interesting. :) Please elaborate on the amps you are using, and how the speakers are configured (bi-amped? etc.)
Thank you!
Erik
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Hi Kenny,
Just to be clear so that there is no misunderstanding that I am not here to advertise my product. I am the manufacturer of the H2O AUDIO amps as some of you here know. But since you are asking, for over 10 years I have used the icepower modules, and specifically the 500A and 250A modules to drive my Apogee Scintillas. These are rated at 500W/4 and 250W/4 respectively. Recently, I have the implemented the NCore 400 modules just to see/hear what is the rave is all about. And it appears that the NCore 400 drives the Scintilllas just fine with one caveat. I have not really push it hard like I do with the icepower modules. And the NCore is still relatively new and is still being breaking in. As for SYNERGY. I really think it is very relevant in any discussion especially with any audio discussion. I will elaborate at a later time as this can take pages to get my point across.
Erik,
I use the icepower 500A and 250A modules. The 250A module which is rated at only 125W/8 but can drive the Scintillas with no problem. For those who are not familiar with Icepower, these modules do not come with the integrated SMPS. I design the H2O amps with my own home brew power supply using these amp modules. Biamp is always better with apogees which I have tried occasionally, but my system is currently configured as single amp with biwire.
Henry |
@h2oaudio
That's fascinating, for two reasons:
1 - I did not know any ICEPower modules were rated for 1 Ohm
2 - The output impedance is quite high at the top octave
Have you measured the speakers with those amps?
Best,
E
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Henry,
Keep us informed with the pairing.I wish you the best of luck.
I have'nt been involved with panels of any kind in a few years and now don't have the room for them anyway.But I did recently over the Christmas break try my pair of nc400's with a friends pair of Infinity kappa 9's with not very good results when pushed a little.The speakers sounded very strained and soundstage collapsed.I know these speakers well because I gave them too him about 15 yrs ago and I bought them new in the day.
The pair were restored by me 3yrs ago,doing the usual surround replacement on the woofers and I replaced all internal wiring and rebuilt the crossovers with better caps.We also tried my pair of ref600m with slightly better results.
It would have been nice to try a higher pwr ice on them nether of us own any.
Henry,
Can you give us any details about your special edition amps?
Kenny.
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georgehifi, Your most recent post, posted last night at 10 p.m., consists entirely of a quote from the author of an article on www.audiophilereview.com, Skip Taylor, that is dated 9/21/2016 and is titled Why We'll Soon Be Living In A Class D World. You and I have both previously linked to this article on this thread; you initially then me subsequently, mistakenly and redundantly. I'm not sure why you felt the need to also post that specific portion of the article again, this time in quote form rather than a link, since your post lacks any pre or post quote comments. atmasphere and I previously expressed concern with the author's inaccurate terminology and his knowledge of how class D actually functions. Now, I want to freely admit upfront again that I do not claim to be technically knowledgeable of electrical engineering generally or how class D functions specifically. Even a class D fan but technical layman such as myself, however, is able to find fault with some of Skip Taylor's article and question whether he has a firm grasp on how class D actually functions. I'll just critique one sentence you quoted from his article to explain my concerns from my layman's perspective: "The greater switching speed of Efficient Power Conversion's (EPC's) eGaN® FETs allow amplifier designers to increase PWM switching frequencies, reduce dead-time, and drastically reduce feedback; in turn, producing a sound quality previously limited to large, complex, heavy Class A amplifier systems."
My concerns with this quote are:
1. I think most are aware that MOSFETS are used as electronic switches in class D amps, required to turn on/off very quickly as the PWM (Pulse-Width-Modulation) circuit's introduced ultrasonic switching frequencies dictate, rather than as linear gain devices as in other traditional linear amps. Given this, I think everyone understands that the new
eGaN® FETs, having the ability to turn on/off much faster than MOSFETS, will allow amplifier designers to increase PWM speed thus reducing dead-time, something called 'shoot through' and distortion. But how do these new
eGaN® FETs allow amplifier designers to increase PWM switching frequencies? He mentions this as if it's a direct result but without any further explanation. He fails to mention whether current PWM switching frequencies are too low and whether they cause any proven audible sonic anomalies in current class D amps' outputs. He also gives no explanations or proven scientific facts as to why higher PWM switching frequencies are desirable or would be beneficial. 2. Skip Taylor states that the new
eGaN® FETs will allow amp designers to drastically reduce feedback in class D amplification, something that may be beneficial in traditional linear amp design but I'm not certain he realizes that reducing feedback in class D amps has no relevance since high levels of feedback is a major factor/tool utilized in good class D amp design. As the inventor of Philips Ice and Hypex NCore class D power modules, Bruno Putzeys, often states: "there is no such thing as too much feedback in class D amp design". While I agree with Skip Taylor's article title that we'll all soon be living in a class D world since many of us already are, I also got the impression from his article that he doesn't have a complete grasp of class D amplification. Please take the above only as the reduced value opinions of a declared layman who isn't as concerned with how class D functions as with how good it already performs. I've been listening to some computer audio music files
as I write this post; Two very good albums from Carmen Gomes that were recorded direct to 96kHz/24bit high-resolution digital: the highly recommended Thousand Shades of Blue and Torn(SE). These downloaded files are one-to-one exact copies of the masters recorded live, unedited, unmixed and without the use of compression in front of a small audience at the legendary Dutch Studio Eleven with just left and right main mics and a few additional mics for the minimal instrumentation. Most songs are intimate- jazz-club like tracks with the beautifully soulful, smooth and sexy lead vocals of Carmen Gomes backed up by a small but very skilled group of clearly jazz/blues influenced musicians on guitar, drums/percussion and double bass. I mention this because I believe the combination of very low distortion, low noise, extremely detailed, completely uncompressed and accurate source material that direct to hi-res digital recording provides paired with the very low distortion, very low noise floor, very neutral tonal quality, powerful dynamic ability, highly detailed and accuracy that good class D amplification allows produces the most life-like and natural reproduction of live music that I've ever been able to attain in my system by a wide margin. Now georgehifi and randy-11, are you both claiming I'm currently attaining this extreme level of system fidelity despite the presence of sonic anomalies in the audible frequency range caused by my class D switching amps' switching frequencies being too low? Have you guys even considered the possibility that your unproven switching frequency theory is unproven for a reason? Do I, and all of the thousands (millions?) of other class D users and fans just have tin ears? Why do only you two contributing thus far on this thread apparently buy into this unproven class D switching theory? Do you both have canine-like hearing and inexplicably obey dog whistle commands? I actually hope you two pooches are correct and class D switching frequencies in the 3-5 mHz range really do eliminate the sonic anomalies that it seems most users cannot currently hear.
I'm just wondering how we'll be able to perceive the absence of something as a sonic improvement when we didn't perceive the presence of that something in the first place. But heck, let's look on the bright side, at least you two good doggies will appreciate and possibly even salivate at the suspect improvement if your theory is correct. Sorry guys, but I think you two 'woofers' may be barking up the wrong tree. Later, Tim |
Tim,
Offcouse I have read all this info before,I appreciate you taking the time to post all of this pertinent info so others can read it too.
I like this statement the best-
I'm just wondering how we'll be able to perceive the absence of something as a sonic improvement when we didn't perceive the presence of that something in the first place.
I have been been blessed to own a lot of really nice gear over the 30 yrs I have been in this hobby,but I really enjoy my present day class d amps.
Kenny.
|
Taking a pure listening approach in evaluating class D
amplification I can say that with most of my experience being with the W4S
STI-1000, ICEpower, it has provided the longest service of audio satisfaction
of any single piece of audio equipment I have owned. I have had it with several generations of
home brewed speakers as well as Gallo Classico CL-4, and currently Gershman Grande
Avant Garde. In the course of the years I
have had in for serious auditioning against them a Pathos Classic One Mk3 which
I found lacked the dynamics, vivid soundstage, and delineation of instruments
of the STI-1000 while having as good or maybe better transparency. I also had a very well modified NY Audio Labs
Moscode 300 that outperformed the Pathos in all manners and edged out the
STI-1000 in most areas of musicality and I would have kept it but for some left
channel reliability problems. I
currently have a pair of Antique Sound Labs Hurricanes with modification by Response
Audio NY and I use them for a change of listening upon occasion. In the end while the two amps are different I
find them to be of equivalent levels of performance. I am, however, more relaxed when using the
STI-1000 because of its proven reliability. I found from the very beginning that the class
D responds very well to improvements in AC power cord and power conditioning as
well as vibration control. And, I have
continued to make improvements in those areas.
Recently, I have bypassed the preamp stage of the STI-1000 and am using
the digital volume control of my front end piece. W4S confirmed for me that the front end still
sees the 60k load impedance as before. In reflecting back on transparency in
comparison to previously mentioned amps I could say that the STI-1000 had a
slight powdery sense within its transparency which was reduced when
bypassing the preamp stage.
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To sell a new product we must sell the problem first, so I can see where a lot of this is coming from.
I don't have a problem with listening to the new when it comes out.
I'm not easily swayed by naked kings though.
Best,
E
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This should be an interesting read for some here. Alex Lidow, Ph.D. CEO and Co-founder of EPC.co. And who happens to be the co-inventer of the Mosfet/Hexfet transistor And now he is leading the way with this higher switching speed GaN-Fet transistor that Technics uses, in their limited SE-R1 Class-D poweramp.
Looks like the GaN Class-D modules have become available, maybe to everyone?
http://epc-co.com/epc/Applications/ClassDAudio.aspx Cheers George |
George,
Those have been on digikey with a 12 week lead time for at least 6 months or so.
I haven't heard of anybody including DIY using them or even ordering them.
The old time will tell saying is in full swing I guess.
Kenny.
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"Tim,
Ofcouse I have read all this info before,I appreciate you taking the time to post all of this pertinent info so others can read it too."
Hi kdude66,
Thank you, but I actually really enjoy reading the Audiogon and other audio and video forum threads on-line and contributing my version of the truth especially when I believe I have useful input based on personal knowledge or experience related to the subject being discussed.
Unfortunately, I had emergency open-heart surgery about 8 yrs ago and suffered a stroke immediately following the surgery when I was relatively young at 51. I recovered my cognitive and speech abilities rather quickly but I’m still trying to coax my paralyzed left limbs back into action. I decided to retire early after consulting with my cardiologist and neurologist and am currently on SS Disability Insurance with a reasonable but fixed income until I reach my actual retirement age in about 8 yrs.
I wasn’t prepared for how much I actually missed my job as an operations manager at a very large (1 million sq. ft), high volume, fast paced and highly automated distribution facility and the people I worked with, Oddly, my dreams often revolve around work and my former colleagues. I’ve even awakened many times in the morning thinking I need to still solve fairly complex problems or employee situations I was dealing with a few minutes earlier in my dreams.
So, while I feel grateful I’m still on ’the right side of the grass’, I’m also grateful for this forum that enables me to keep learning from other members about this hobby I’ve enjoyed for decades and post my thoughts when I think I can contribute constructively on certain subjects.
As my typically overly long posts indicate, I now have plenty of spare time to read and respond when I may be useful to forum threads, too.
Like this thread for example. I initially learned of class D amps from positive comments on various audio threads. I purposely began researching all I could on the subject here and on other sites and I credit my own quasi-scientific readings on the over 60 yr history of class D amp development along with the forum posts of class D guru Guido Corona and a few other members with exceptional knowledge and experience.
After my older class A/B amp went belly up due to leaking caps a few yrs ago, it was the perfect time to take the plunge and start gaining some personal experience with class D and I bought my first amp, a Class D Audio SDS-440-CS stereo unit that was superior in virtually every aspect that audiophiles care about in an amp. I was so impressed that I replaced the other 2 class A/B amps I used in my combo 2-ch music and 5.1 HT surround system with relatively inexpensive class D amps; a Emerald Physics EP-100.2 stereo unit and most recently a pair of D-Sonic M3-600-M mono-blocks.
When I read posts from members like georgehifi and randy-11 about a theoretical issue with class D amps switching frequencies needing to be dramatically raised to avoid affecting frequencies in the human audible hearing range without presenting any semblance of even anecdotal evidence that it’s true, makes me seriously suspicious of their true motives for spreading and trying to validate something that I highly doubt 99%plus of humans could even begin to detect, although I believe at least georgehifi has heard a good class D amp and acknowledged how good they currently are but is going to wait for his view of perfection. I’m not even sure if either one of these guys has personally heard any sonic anomalies from a class D amp.
As far as I’m concerned, they’re in my doghouse until they can cite a SPECK (as in Peewee Herman’s dog) OF EVIDENCE.
Tim
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When I read posts from members like georgehifi and randy-11 about a theoretical issue with class D amps switching frequencies needing to be dramatically raised to avoid affecting frequencies in the human audible hearing range without presenting any semblance of even anecdotal evidence that it’s true, makes me seriously suspicious of their true motives for spreading and trying to validate something that I highly doubt 99%plus of humans could even begin to detect By saying this, a little better explanation is needed. It’s the output filter to rid that switching frequency completely, that is the problem, not the switching frequency by itself. As that output filter has phase effects down to 5khz, the upper midrange and highs. And by moving it (output filter) and the switching frequency much higher, takes those effects at 5khz upwards by the same amount, hopefully passed 20khz. Why I ask then are these transistors developments happening, if not to do anything good? Forest and trees. Cheers George |
Hi Erik,
Well, It is not rated doesn’t mean it can not drive it. It is just that the designer didn’t test it with such a load. The same goes for the NCore. And to be fair, Apogee is no more for many many years and very few own the 1 ohm scintillas. So it is not a very popular speakers so there iI can see why there is no point in testing the amp with such a load. No worry about impedance, it is low enough, besides lower output impedance is not necessarily better or conversely, high output impedance is necessarily bad as you can have too much of a good thing knowhatImean :-)? I think you read a bit too much into spec at time. Don’t get me wrong. I am not saying that spec is not important It all depends on the system as I have alluded to. No I have not measured the Scintillas with these amps.
Kenny, Thanks for the good wishes. And yes I will keep you posted as long as no one here thinks that I am here to sell products :-). The H2O Special Edition uses the icepower modules 500A. has 1KW transformer and lots capacitance filtering reserves. I have implemented with many other goodies which is too long to list here. These are rated at 250Watts/8 and double that into 4 ohms. Don’t let the power fools you though. These will put the biggest boat anchors from Krell, Levinson and the likes into shame when it comes to liquidities, smoothness, extension, control subtleties, dynamic, composer when push hard :-). And should I go on? Oh even some class D too. LOL.
BTW, I spent 2 hours wrote about 3 pages long. Took a break and came back to continue and everything I wrote disappeared. This stupid computer. Not sure what happens.
Henry
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@h2oaudio
What you do with your amplifiers is between you and your part supplier, but these are high current outputs. Unless specifically rated for such low loads I would never encourage anyone to attempt this without further input from the manufacturer. :)
Um, as a guy who makes loudspeakers, no, I don’t know what you mean, but measurement and experience trumps theory. It would be interesting to examine what happens to the output response on those scintillas, as they are pretty much the worst case scenario. :)
Honestly, those speakers were absolutely brutal. If ICEPower modules can drive them as well as you say they do that’s pretty astonishing, even for me, an obvious fanboy. I think the biggest, most lasting impression they have left on the audio industry was to give Krell a raison d’être. I think without Apogee loudspeakers the history and viability of Krell might have gone a different way.
Best,
E
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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. 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. Only the biggest heaviest Refererence Monoblock Krells of yesteryear can drive those sort of loads and sound good. To quote a great Australian movie (The Castle) "Tell'im he's dreaming son." https://www.youtube.com/watch?v=dik_wnOE4dk Cheers George |
George,
If I'm not mistaken,do you still have a pair of ref600m.
If so what amps do you like better and what speakers do you use.
Just curious.
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,
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.
|
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.
|
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
|
John,
Thanks for asking George that question as I forgot and really very puzzled as to where he got that from.
Henry |
@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
|
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 |
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 |
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
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Henry,
I would be more inclined to measure the in room response of your speakers and see what you get.
Kenny. |
John,
It is very rare to find a Scintillas owner. Are you located in Texas?
Henry |
Kenny,
Unfortunately, I am not very well equipped with instruments to perform such tasks.
Henry |
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 |
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. |
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 |
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
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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.
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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 |
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
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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
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Ah, fine. :) That's fancy.
All we really need is a signal generator, and voltage meter at a couple of frequencies.
Best,
E
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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.
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