Let me go back to what @atmasphere objected to.
The biggest issue with input/output impedance is the change in frequency response...
I was very specific in what I was talking about. I did not say "the biggest issue with tube preamp sound quality." I said the issue with "input/output impedance." If you see another issue with input/output impedance to be more important, please show your work. Best, E |
Let’s simplify this. I wrote this: The biggest issue with input/output impedance is the change in frequency response....(followed by supporting discussion with links to external sources)
You replied: This is mostly misleading or outright false. Now your latest posts seem to be supporting my argument. I’m not sure you even read what I wrote before you claimed it was a lie or misleading, but you launch into discussions about how Atmasphere preamps are different (which while informative does not make your case that I was wrong). So I challenge your "statement of fact" as having anything which directly refutes my statement with evidence. Best, E |
@atmasphere Wrote: As we can see, if one is to point at a tube preamp and blame it for a change in frequency response, I don’t "blame" preamps for changes in frequency response. I say high output impedance causes frequency response changes which vary based on the load. This is an irrefutable fact based on simple serial circuit analysis. Anyone with a basic understanding of AC circuit analysis would conclude the same. It is also irrefutable that in general, tube preamps have higher output impedance than solid state. That is different than saying preamp X sucks, which is what you seem to have read. the factor is not the output impedance (which is often only stated at 1KHz), its the coupling cap at the output. That is a bit different from ’output impedance’ and that is why I placed the correction.
A - I never limited myself to 1 kHz B - It makes no sense to talk about changes in frequency response if i was talking about a single point C - The coupling cap is a major if not THE major contributor to output impedance. However it is not the only issue. I never said it was. The factors that go into any devices output impedance is more complicated, but includes the coupling cap if any. There is no logical way to make both of these statements true at the same time: - Tube preamps don't have a problem with output impedance
- The problem with tube preamps is the impedance of the coupling cap
Since the first includes the second, you can't have both of these be true at the same time.
Best, E |
Hi @autre
I got to hear the NAD Master series DAC two years ago. Cold, it was a painful screech.
I never heard it well warmed up, so I would strongly caution you to get a good listen yourself.
I also heard Arcam, MUCH MUCH nicer. Like an inexpensive Ayre.
Best,
E
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Al -
Yeeeeep.
Otherwise I would have said "resistance" and wouldn’t be pointing to frequency dependent graphs to illustrate the magnitude of the effects.
Best,
Erik
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@randy-11
I think Class D is as good as many Class A or AB designs. It may sound different, as some amps will sound different to each other regardless of the technology. Some may also deal with different speakers differently, just like Class A/AB designs.
I think there are some very affordable great sounding Class D amps right now. Please skim this thread for a number of good suggestions, and listen for yourself.
My Class D monoblocks sound as good as mega-buck class A amps to me.
Let’s say my hearing is impaired (for argument’s sake). Why would I buy anything more expensive I don’t hear an improvement for? :)
Best,
E
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autre,
ICEPower AS/ASP is very very good.
Hypex definitely has some improvements in output impedance, but whether this is a good or bad thing is going to be a matter of amp/speaker synergy.
I would say that the current crop is so good you owe it to yourself to listen. :)
Best,
E
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Thanks Autre!
I had not really noticed the ASC line before, interesting. Half the damping factor, with ratings for minimum speaker impedance.
Apparently designed to be less rugged, but also offer a universal supply (ASP has a jumper to select).
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@ebm
I really appreciate your careful reading of the purpose of this thread, not to mention your thoughtful and nuanced contribution to the hobby in general.
I can only hope that the you can contribute as much for others in your life.
Best,
E
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@randy-11
I am a huge Mytek fan, Randy, how did you learn about the amp? I haven’t heard a peep about it.
Best,
E
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I will say, for the form factor, the Mytek is really small, even for a digital amp. I'm VERY curious to know what is inside it. :) A scaled down nCore? Pair of Pascal amps???? Hmmmm......my screwdrivers scream to be let loose to see inside. :)
I'm such a fanboy Mytek should send me a prototoype. :)
Best,
E
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George,
It is an open forum. That gives me the right to every single word in my last post.
Cheers,
Erik |
let us know, Ricred!! :)
E
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Thanks for the support, @asvjerry our contributors make this thread worth participating in.
Best,
E
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Hi @merrillaudio Welcome. I'd like to ask you a few questions about what you pointed out.
However as with all transistors, there is a lag between the command to
switch and the actual full switch. This is call the dead time. This has
been reduced over the years with faster transistors and also limited
with feedback. But it is fast. Hence the apparent speed of Class D
also.
Sorry, could you be mistaking "switching time" with "dead time?" As I understand, you are talking about switching time. How long to go fron on to off, or vice-versa. I think "dead-time" is a little different. As I understood, the problem with bi-polar PWM amplifiers (uses + and - V at the transistors) is that you must NOT have the positive and negative sides on at the same time. This affects both efficiency and distortion. I link Wikipedia and a B&O brochure discussing it. (The PDF is a little easier to get). https://granitedevices.com/wiki/Dead-time_distortionhttp://www.icepower.bang-olufsen.com/files/solutions/iceedge_brochure_final_20150624.pdfBy the way, this issue with multiple transistors being on at the same time plagued Carver for many years. :) but in his case, he was switching among multiple voltages of the same polarity. Eventually it was solved by reducing the switching speed. Best, E |
In the professional world, "bi-amping" a single speaker system is always active, meaning it uses an active crossover before the amps. Multi-way active speakers also use this type of crossover.
Only in the consumer world is there a question of whether or not to use a crossover when bi-amping, hence the confusion.
Far too many types of crossovers further confuse this, because while most line-level crossovers are "active" or powered, a rare few are passive.
Best,
E
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Can’t really argue with that. :) The separates craze creates it’s own list of extra problems to solve.
At the same time, I really really like selecting my own parts. I find it a real difficult thing to want to give control to some one else as to what makes my system.
If I could, a two box system with a 5 channel amp and HT processor would have been here long ago. :)
Best,
E
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in excess of 100MHz- and likely with no need for dead time circuitry
This would be a spectacular improvement upon the state of the art. I can't wait to see it in real life. Don't even need a working amplifier to try this, just hook up two tubes and have them switch back and forth as you suggest. Please post the pics of the results. By pics, I mean of the smoke. :) Best, Erik |
Hi @rhale64 and welcome!
Funny you mention the Parasound A23’s.
I have to say that going to Class D did not improve imaging. I found the A23’s in my set up to be great imaging amps. Maybe because I ran them as dual mono? I used them in a 4.1 channel setup, so one amp was L /LS and the other R/RS.
I have always gotten that sense of music coming out of nowhere with these speakers, whether it was class A/AB or D. As I recall, the one technical area where the Parasound stereo amps are a little weak are in the crosstalk spec.
I am very happy you are having such a great experience with a multi-channel amp though, I need to run 5 channels, and having a single unit would make things easier. :)
Best,
E
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Welcome @nonoise
I must say, AA makes some of the very best looking gear. :) Also, there are a number of new (< 5years) dacs which sound outstanding at any resolution, and make Hi-Res and SACD less important to me.
Thanks @mdeblanc glad you found a good resource. Let us know what you listen to and what you end up buying.
Best,
E
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Todd,
Interesting! Those modules are 2x more expensive. :)
Best,
E
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One biased reporter backing another doesn't convince me of a thing. Sorry.
Everyone should use their own ears and definitely not Fremer's or JA when evaluating modern class D amps.
Best,
E
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Fremer's 2013 review was riddled with bias. He's no neutral observer.
What should you buy? Class A? Class D? I dunno. But don't come and tell me the best of each aren't very very good.
Best,
E
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BTW, I have no particular opinion on ML amps, but the generalized claims Fremer made in the article were just not true anymore for Class D amps.
Whether any reader here likes a particular amp or not, well, OK, I can't argue with that. But the general issues with Class D amps of the 1980's were long solved by 2013, despite some people being unwilling to let go of the same old myths.
Best,
E
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That discussion belongs in another thread, George, but practically everything you complain about on a weekly basis. Hahahaha
This thread is for talking about Class D amps we actually like.
Best,
E
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Hi @chrisr
Class D is not Digital, but for the next type in sequence, after A, B, C.
They are switching amps, but everything is controlled in the analog domain. Designers like Bruno Putzeys bristle at the term "digital" amplifiers.
There is no A/D or D/A process. At least, not how DAC's think of them.
Some class D are also digital, but rather rare. I'm thinking of the latest Technics amps.
So, no, most Class D amps take in analog signals only.
Best,
E
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@kuribo
Hey there!
I'm thinking of spending for a pair of Hypex monoblocks soon. Could you please tell me your thoughts on the sound, and especially if you have compared them to ICEPower?
Thank you,
E
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BTW, I've had a number of golden eared audiophiles listen to my system. The issue of Class D never comes up until the end. No one ever says "OH, wow, I can hear the Class D problems!"
We talk music, headphones, speakers, and room acoustics. On the way out some one will ask, "Oh by the way, where are your amps??"
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So George would like you to believe all Class D amps have issues, but this one future amp finally fixes "The class D problem." and reviews say so.
Hahahah.
BTW, technically this may actually be a Digital Class D amp, given the A/D conversion and processing.
Best,
E
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The non-existent problems? Oh, but wait, they only address the non-existant problems but never actually solve them. Damn. And all that money.
Maybe people should just stick with inexpensive Class D amps available already which fixes it all.
George has nothing but shade. WEEPS.
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@sfseay So long as your wallet is the one talking, that's how it should be!
E
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@asvjerry
I cannot hear the difference between my class D amps and Parasound A23s. Zero. None. Therefore, small, lower stand-by power wins.
But there are interesting hybrids. NuForce is basically class D voltage rails + Class A linear amp. Yamaha’s EEEngine technology is similar.
Both could be considered derivative of the NAD/Carver voltage tracking power supplies.
Best,
E
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Hi Tim,
That is interesting, George has been hawking this for a while.
However, since I cannot hear any problems with good class D, I won't be put out if I stick with "slow" transistors. They work just fine for me.
One really interesting thing about the Technics however is the heavy DSP processing they rely on to flatten the electrical amplitude and phase response. I'm tempted to do this with a miniDSP to see if I hear any benefits.
Not any time soon though, this apartment doesn't lend itself well and I'm all out of funding. :)
Best,
E
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When I'm watchin' my tv and a man comes on and tell me
How white my shirts can be
But, he can't be a man 'cause he doesn't smoke
The same cigarettes as me
- The Rolling Stones, 1965 |
So I know people are used to me laughing at most 1980’s attitudes about Class D. However, the reality is that some Class D can emit a lot of RF noise, I think Putzeys writes somewhere that it can actually cause cross-interference if two Class D amps are too close together. Will, it’s worth investigating HOW that interference is happening. It could be via the case, power or interconnects. If in the interconnects, or power cord, using snap-on ferrite donuts can tame it. Something like this could be useful, but check the inner diameter: http://amzn.to/2sGdR49Worth trying on the tuner's AC cord as well. Best, E |
Nothing shows respect for the people you are interacting with less than straw man arguments and innuendos.
I’m really unhappy to see it here.
Best,
E
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Delta Sigma processing = digital. :)
Most Class D amps are not digital. Weird. :)
Best,
E
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Hi Everyone, Just FYI, Mytek has just posted info on their Class D amp to their web site. The Mytek Amp fits perfectly under a Brooklyn DAC for a little under $2k. Order with the Brooklyn DAC and you get a $500 package discount ($3500 or so) which is a really good deal. More here: https://mytekdigital.com/hifi/products/brooklyn_amp/For the power rating (250W/Ch) this is one of the smallest Class D amps I’ve ever seen. I can’t wait to look inside it! :) Erik |
Atmasphere,
If you use a delta-sigma encoding process, you are converting analog to digital, no? This AD conversion makes the amps "digital" a step most Class D amps do not need.
Otherwise, please show an example of a Class D amp which uses Delta-Sigma conversion which is not "digital"
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I’m bringing this over from another thread, but Primare seems to be using their own digital amp modules, and Hi Fi News test reports praises their performance, unaffected by load, and flat to 60 kHz is quite a feat! I also noticed how well Hi Fi is keeping track of Class D. Their comments about the relative differences between Class D modules shows they are taking the genre quite seriously, unlike say Stereophile, which has never bothered. http://www.primare.net/assets/_managed/products/files/I32HiFiNews611UK.pdfBest, E |
Which is why I'm keeping it short.
E
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So apparently a short version was considered abusive. I thought I was being concise. This is me being perfectly reasonable.
The best educators lead by example. Those who show a willingness to listen, learn and adapt instill the same in others. I look forward to seeing more of that in this thread.
Best,
E
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Hi Dan,
I don't know enough about your amps to help you I am afraid. The DIYAudio web site is a great resource for kits and components.
The site is down for upgrading, but should be back up by Monday, July 10, 2017. I would ask there.
While some digital amps have noise issues when you put modules too close together, I would not think this was an issue. I would suggest try unplugging all but 1 module, and see if that does anything to the sound quality. If so I wonder if your issue is proximity.
Best,
E
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Here today gone tomorrow world of digital parts and design would make me seriously think about putting serious money into a product that may have obsolete parts in the future that aren’t available. I have to say the modules I’ve seen were barely serviceable. I like the sound of the ICEpower modules, but having attempted to service several of them which arrived with broken off caps, it was a real challenge. They are packed tight and with little care for easy disassembly and re-work. Every other amplifier I've worked on fell apart (in a good way) as soon as I realized where the screws were that were holding it together. |
My goal was a little desktop integrated or pre/amp combo.
After hemming and hawing and fretting I purchased an NAD D 3020. My local dealer had one $100 off.
I ruled out all of the Parasound Z series just because they are too big. at 9" wide they wouldn't fit on top of a speaker, like I need.
Plenty of digital and a couple of analog inputs make the input selection pretty good. There is also a bass boost which is perfect for my little desktop speakers.
So far so good. The one negative is really the volume display is hokey as hell, and it takes a lot of turns to adjust it.
The display has a series of numbers: -20, 40, -60, -80 and -100. As you turn the volume down the numbers dim, or go off. The physically larger sibling the 7050 has a graphical display with direct volume readings in dB. It was only a little more expensive, but seemed to lack analog inputs and was twice the physical size.
They call this a hybrid digital, but I could not find much information on what makes it a hybrid.
My only source right now is the PC, via analog, but I'm always careful to get motherboards with S/PDIF outputs so I'll try that eventually.
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