Rivendell61

DrWho-- This is not true (assuming I am reading you correctly). There is nothing 'inherent in the topology' of Class D amps which would make the distortion plots act 'weird'. It sounds a bit like you are saying "I built a lousy Class D amp....therefore all Class D amps are lousy". There are poor designs in all types of amps. A well designed Class D amp will have distortion as low (or lower) throughout it power range as a well built linear (Class A/B) amp. In fact, the very low distortion of some Class D amps in the sub-1 watt area should make them particularly good with very efficient speakers ala Klipsch. Mark

DrWho, there is a 'theoretically' definable limit for unbalanced (or any) signal. However, from the numbers you are quoting I bet you are thinking of SPDIF or USB?, which have c. 30/15 ft region limits. Here is an example of a defined limit for unbalanced RCA: Benchmark Media state that for the DAC1 unbalanced output (low impedance! = 30 Ohms), using something like Mogami 2944 (they spec 32 pF/foot--Mogami is lower) 1360 foot of unbalanced cable would be the maximum. That is based on a self imposed 'theoretical' limit of no more than 0.1 dB loss at 20 kHz. Which, of course, is not to say that Tigerwoodkhorn can run even 25ft!....local factors of poorly designed equipment grounds or lousy RFI design on some local amp/DAC, etc., may impose limits. Mark

There is a distinction made (above) between demands of HT and music/orchestras, etc. Well, I'll just note that some well recorded 'classical' (I would guess not so with rock) music will be quite demanding. I have a CD (Prokofiev) which if you want to: a) Not compress the peaks and Hear the quiet bits You would (sitting at 10 ft--and with the above mentioned 100dB speakers) need.....c.300 watts. Mark

Tom, You might look at the Hypex class D amps. Great specs. Very neutral. They publish the THD vs Power plots and at .5 watts they are sub .005% THD. A nice 100k Ohms input impedance (don't you have a passive pre?). Balanced or unbalanced. Flat frequency into all loads.... They are incorporated in a few amp manufacturers products but can also be bought as simple kits. Mark Edit: here is a link to a datasheet: http://www.hypex.nl/docs/UcD400_datasheet.pdf

You might re-read your source..... Mark Edit: Jay, your source says aluminum--but other metals can be used (gold most prominently--certainly silver could I should think). The point being the known issues with CD failure relate to oxidation of the metal layer--most commonly aluminum as in the PDO 'bronzing' (look up CD Bronzing). If the layer of protection is not breached the CD will be fine.

Jay, That is the comment I was responding to where you state CDs use dye. CDs do not use dye--only CDRs. I did not say anything about distortion or sound quality. CD information is coded in plastic which is metalized with Aluminum (the vast majority)--some use gold. I doubt any use silver.... Mark

Gil (and Jacksonbart) are correct here..... There is no degradation of CDs. Jay is conflating CD information and CDR information: a CDR uses a dye layer and that dye will fail over time (Taiyo Yuden says 100 yrs if stored like you would keep film negatives--but leave one in the sun and....). Standard CDs are encoded in Aluminum (usually) and they are completly stable if the seal is not breached. CDs made by PDO (Philips Dupont Optical) between 1988 and 1993 used a bad laquer layer to seal the CDs and those will fail (and are failing). The fragile portion of a CD is the top. The laquer is very thin and any mechanical abrasion that breaches the seal and allows in air will cause the aluminum to oxidize. But....most CDs should outlive their owners. Mark

Another to compare with the Olive is the Cambridge 640H (see below). There may be some reason to use caution re the Olive Opus but the EU made Olives (Symphony, etc) seem to be OK.

The RIAA (always controversial) 2005 year-end numbers were: LP/EP sales 1.02 million, down 25% from 2004. (CD sales 705.4 million, down 8% from 2004.) Mark

Kev313, Hoffman got rid of the HE-833 a few years ago. I would be cautious about the idea he used them to power his mastering speakers for normal use. He also gets personal visits from the WAVAC folks who give him amps--then they get photos and mention on his site--he is (unlike most MEs) quite secretive about the gear he uses for mastering. Hoffman also had a WAVAC 300B "in the mastering chain"--but not to power speakers--it was an 'attempt' to see if he could get the 300B sound by adding it to the amps powering his record cutting lathe. Not sure if that worked out-- Mark

Just FYI: The Hypex/UcD based switching amps are unconditionally stable with no load attached--even at full vol/clipping. No problem at resonant frequency. Mark

This is sposed to be quite good at it.

I will hazard a guess that Mr Spinner intended to convey the importance of something like "optimizing the impedance relationship"--rather than advocating the specific technique of 'Impedance Matching'? Mark

I've also been looking at the various methods for getting a signal out to my computer 2.1 speakers--many options. So why USB? Is it a laptop? I was looking at USB options but am now looking more toward a PCI card with digital out to a DAC. Re USB options here is one (c. $240): http://www.roland.com/products/en/UA-25/index.html Some prefer the previous version because it has an independant AC power source: http://www.roland.com/products/en/UA-5/specs.html Mark

Jazz historian and trumpet player Richard Sudhalter is ill, needs funds, and is selling his LP collection. 5000 jazz LPs "from King Oliver to John Coltrane". FYI, one of his books: http://www.us.oup.com/us/catalog/general/subject/Music/MusicHistoryAmerican/?view=usa&ci=9780195168983 I believe he is seeking a single buyer. Mark

Peter, The Boyk paper (next comes Oohashi) has been bouncing around audio web sites for a long time, and I don't think the general premiss is much disputed--or new. What it does not address is the desirability of reproducing that high frequency information. That question seems to be always answered in the negative (if we want to get an accurate representation of the event in the audible range). And there is vinyl.... Until the mid-60's or so it was limited to about a 12kHz top. And modern Lps usually top out at c.15+kHz. There are claims of higher than 20kHz frequencies being possible--but this is not the norm, even on 'audiophile' releases. Yet no one seems to complain about a lack of top end. So....not sure why this high frequency thing gets advocated by vinyl folks. Lots of effort (by Sony, Philips, etc) went into finding some excuse for ultrasonic reproduction due to SACD, DVD-A, etc. But there has been zero evidence (in theory or listening tests) discovered to date. In fact there are significant arguments against running ultrasonics through amplifiers and speakers (Kaoru and I believe Griesinger have written on this). Mark

Well if it is of any use to you here is the Whitlock url: http://www.aes.org/sections/pnw/pnwrecaps/2005/whitlock/whitlock_pnw05.pdf Parts of it are sales talk (Jensen Transformer) but also lots of good info. Wheatstone bridge is mentioned on p.46. Another good presentation on the subject is by Bruce Hofer (of Audio Precision): http://www.aes-section.nl/project%20157/Analog%20Signal%20Connection.pdf Both of these guys make the point that the primary benefit of balanced in a consumer system is not going to be rejection of external noise but of noise from the significant ground potential difference between components present in unbalanced. (don't understand....I have these on my computer as Power Points but the urls show as pdfs....) Mark

Mike, Are you looking for that PP article by Bill Whitlock? Here is a short excellent article by him (not the PP thing) on what 'balanced' is (as Shawn says above--equal impedance) and how to inter-connect balanced and un-balanced. http://svconline.com/mag/avinstall_mixandmatch_interfaces/index.html Mark

Gary, Attached is a link to a 'single post' from Hoffman Forum. Re using two speakers for mono causing tonal problems. The boxed area of the post is an explanation from Robert Greene (Absolute Sound): http://www.stevehoffman.tv/forums/showpost.php?p=838351&postcount=80 Mark

So you are talking about the latency of the unit: the delay from input to output. 3 sec? Latency in converters is very low (c. 2ms) and the difference between brands is on the order of a millisecond. But I was not denying any utility for external clocking when using multiple units. I thought you were suggesting it might help a stand-alone player. I was addressing a different subject: My saying there was no timing error out of a DAC was to point out that the common idea that digital sampling introduces timing error to the output is wrong. So using that idea to rationalize higher sample rates is not helpful. Here is a link on that subject: http://recforums.prosoundweb.com/index.php/t/7308/8269/?SQ=a8e348fb56f27ca9826fae64977fc7a5 "Micro-timing in low sample rates" A 4-5 page Forum discussion with some interesting plots posted. It takes a page or so to get going but there is some interesting stuff (if you are interested in this sort of thing!). There is also some brief commentary on Apogee towards the end.... Mark

OK, I think there are three subjects here. 1) Re Timing Error: there is no timing error at the output of a DAC. And sample rate has no influence on timing resolution. Internally any very small timing error (nanosecond stuff) becomes white noise which is....down in the noise floor (i.e., a non-issue). 2) Yes, moving up from 44.1 a bit may indeed be an improvement. But as you note that is not intrinsic to the increased rate (i.e., not regarding the capture/sample rate) but it comes from helping poor filters at the output. However, once you get past the 88/96 area the computational degradation negates that. For this same reason most DACs now run at very high (mHz) rates internally--but again, this is nothing to do with the "audio sample rate". So, 192kHz is crapping up the signal for no benefit. 3) Some manufacturers (e.g., Apogee) try to sell the idea of external clocks--but I think you will find that most EEs who deal in converters will disagree. The local clock is almost always going to be better than an external. DrWho, I don't want to hijack this thread to a digital discussion but if you want some links re the points above I can provide some (I don't expect you are likely to take my word on it!). Mark

I am curious though why you think 192kHz should sound worse...do they sacrifice accuracy to achieve the larger bandwidth? DrWho, Yes, exactly. Although note....I said 'signal damage', i.e., there is a loss of accuracy--which does not necessarily translate into your more subjective expression: 'sounds worse' (e.g., the current discussion--). There are a couple of pro-oriented converter makers who refuse on principle to make a DAC with a signal rate of 192kHz (Benchmark is one), but most go along since sales are lost if they do not provide the 'better', 'hi-rez' converter. This is, no doubt, all derived from the misconception that an increased sample rate will improve something called 'resolution'--when it really only changes frequency response. Resolution is not a real issue. There are no subtle, inter-sample, sound artifacts which are 'lost' at lower sample rates. Although this is a pervasive belief among audiophiles and audio engineers. Impulse response arguments get brought in here, etc-- This brings me back to the subject at hand. Some of the more interesting vinyl advocates have oddly adopted those digital arguments (the bogus ones mind you) about fast sampling to provide technical validation to their subjective preference. So you will sometimes see it claimed that since vinyl is analog it has a continuous, smooth, 'infinite' sample rate, thus being superior.... Oh well. Mark

I don't know how to do quote things on this forum.... Mdeneen--mentioned CDs having a "deadly lifeless sound where vinyl sounds lifelike and lively". Intereresting considering the notable potential dynamic range of CDs (manifested in some of my classical CDs with +50dB peak to peak)--could this be simply reflecting well known mastering issues in popular music? OTOH, I was reading a Microsoft PP presentation last night (what exciting evenings I have) on the differentiation between 'Intensity' (SPL) and 'loudness', and an example of vinyl was mentioned: "LP distortion grows with level. That means that as level grows, the signal bandwidth (including distortion) increases. --This means that an increase in intensity is over-represented by the increase in loudness. * This can create an illusion of 'More dynamic range'* ". Perhaps your 'lively' is a 'non-linearity'.....? jdm56--good post but one point:....wider bandwidth is one of the easiest to discard of possible reasons for the the perceived vinyl advantage (for several reasons). Consider one: people on this very forum have extolled the sonics of 1950's and 60's era vinyl. DrWho--I see a 192kHz mention.....uh oh. Speed kills. Faster is not always better and while audiophiles love the idea of 'faster', all converters will create more signal damage at 192 than at 88/96. It is a sales tool only (as is 'resolution', 'hi-rez', etc). Mark

Paul, The Burmester CDP and Transport also use 'belt drive'. They may have more info out on the Net than CEC re how the drives work. Mark

Max, I skimmed your earlier DIY post but somehow missed the Hawk reference--or I would have known you were building a Hypex based amp. The UcD modules have the potential to perform in the "as good as it gets" category (especially with efficient speakers: they have very low distortion in the sub-watt area). But it is all in the 'implementation' (op-amp choices, board modification, power supplies, layout, etc) and I have no idea how good the Hawk kits are. On to your query: yes, they are analog. Pure analog from stem to stern--just like Tripath (but much better). There are some Class D amps which are indeed digital or 'pseudo' digital, like the TacT, and the Sony Equibit--but sonically they are also not competative with your Hypex. You asked for some explanation. Here is a post by the guy who designed the UcD. It is a 'philosophical' vs 'technical' explanation of analog amps vs digital amps--and it is surprising just how difficult it is to distinguish the two....but it pertains to your amp. And really a nice bit of audio writing....IMHO: http://www.diyaudio.com/forums/showthread.php?s=378815689596de04047a8936bdf23a22&postid=635641&highlight=#post635641 (Reading on a bit in the thread--post#5--there is discussion of a 'digital' amp as well) He also gave a paper at the just passed 2006 AES meeting in Paris which is more technical on the same subject. I can find a link if that interests you. Do you know Kharma speakers? You might find this review of the new Kharma amp interesting. I can not be too specific here but I can say that if your Hawk amp module is a UcD 180 this may be very similar..... http://www.positive-feedback.com/Issue25/kharma_mp150.htm I know it's a meaningless 'subjective' review, but the last sentence re the $18000 DarTZeel is mildly heartwarming. The Graham's bottle is empty, and it is 5:30 am. Time for a nap...... Mark