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dacboy

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About dacboy

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  • Headphones
    cheap pc type (my reference)
  • Headphone amplifiers
    diy tube preamp.
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    vcd/dvd players
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  1. For Sennheiser,there is a shop on the third floor of Sim Lim Square to the left in front of the escalator.Sorry I can't remember the name.
  2. HI fir3dp, You are the boss my friend and by the time you set up a good system you would have spent a considerable amount of money.Well if money you must spend then spend it on something that do the job.Since PC sound is what you most listen to , Creative EMU 0404 midi interface It is USB 2.0 and has a headphone output meaning builtin opamp but the power supply is switchmode so not exactly audiophile standard.To really experience what is high resolution 24/192khz. digital audio. Of course you will need the required software like flac and what is described in the advanced mod below. However for advanced modders you can upgrade to audiophile standard here Which I think you are not up to it so don't attempt it but may give you ideas to improve? You can go down to Creative's showroom in Jurong east and have a look. regards.
  3. Hi, Unfortunately the Common PCM290X chips by TI/BB or other brands implement a cheap solution so you are back to square one.Manufacturers go for lowest cost ,highest profit margin and easy trouble free design in fact they just use TI recommened circuit. A separate usb interface with a standalone DAC ic is better but I have not seen any on the market. . regards. BTW the X can ver8 sports a PCM2706 so you are really back to square one and it has a tube buffer. like I said they slap on a cheap solution ,add a tube buffer and brand label and charge a hefty profit for it.That's Musical Fedelity UK style. Hey it's your money. cheers.
  4. Hi , By the way there are some help or readme files in english in the main directory after installtion of VA. I have since discovered that if you use 16 bit sound card like soundblaster live,in the settings tab, device tab you can select your soundcard and increase the spectrum analyser bandwith with 96khz. sampling to get 40Khz. but if you use 24/196khz. soundcard you can get 93khz. as Nyquist theorem states that half of sampling frequency is possible. I have notice my soundblaster live card shows soundcard noise to average around -120db.I was hoping to make it lower or cleaner as the peaks are all over the place.Apart from using better caps I don't think I can't do much because it is troublesome. regards.
  5. Hi bribadi, I have not built the jung super regulator as you know the people who help to implement it at diyaudio is very protective of it's IP ( interlectual property) of the circuit but as you know one cannot copyright a circuit so it is in public domain so to speak.Nonetheless jung had some clever tricks done.On paper the design is easy but when you want to make it there are a number of obstacles such as the components used like LM329 which by now could be obsolete or NS only makes it as a 6.8v voltage reference is not commonly used nowadays though you can still find it in electronic catalogs. The last revision was in 2000.Looks like it's largely "forgotten" and the following paragraph may reveal the "difficulty". If you try to substitute the original components or change values you may get an unstable circuit. so this is a major hurdle as I see it.I am trying to find a less complicated solution of course with not as good performance as jung super regulator but still serve a purpose in high end audio like a MC phono stage.The Lm49990 can be a part of the solution.By the way the jung super reg does use a LM317 as preregulator to inprove performance in a floating arrangement. Regards.
  6. Hi, This is only my opinion. Are you sure there are no reviews diferenciating between DT880 models? Or are you an audio virgin? Well to be fair I can't blame you but you have to learn your craft or else you will be conned through and through or as they say the sharks will rip your clothes off.By the way I'm not a guru but I'm knowledgable enough to give you some advice or tips? First look at DT880 frequency response http://www.headphone.com/headphone/beyerdynamic-dt-880.php In speaker design you try to achieve a flat frequency response in order to say it will reproduce all frequencies at the same amplitude or level which make it sound neutral.But in real life it is not but you still try and look at DT880 a hump at the mid frequency (voice) where your ears are most sensitive ,a dip from 1khz to 5khz and jagged peaks at the high frequencies at around 10khz.This will mean the highs are over emphasized and will sound bright. You have to be knowlegable and read between the lines of reviews.Although the reviewer's job is to sell the product but some reviewer does not want to betray his own conscience so he puts it in a diplomatic way in order to appear that he sides the product but is also telling the truth in an oblique way. See the 6 moons review of DT880. http://www.6moons.com/audioreviews/beyer/dt880.html Here 6 moons say DT880 is bright and the highs are "noticeable" and is not as neutal in true audiophile fashion.Mind you it is advertised as a studio monitor headphone and as a recording engineer you would want a neutral one to do mixing and mastering. I'm not too sure about the product development stages and timeline but it appears that DDT880 pro was introduced in 2005 and the impedanced was and still is 250 ohm.Lately there is a 600 ohm version.I wonder if there is a 32 ohm version as this is a "high end" one.As to the different models... Pro,consumer they are just cosmetics.Although there is a difference being that the first DT880 of 2005 is a close back one where else the 2008 DT880 I think is stated as semi closed . All this diversion and you will notice Beyer nor anyone talks about the star which is the driver in the headphone. Makes you wonder does'nt it? Are they all the same? well if to look at DT880 frequency response the plot is of a raw driver or in the enclosure, there could be no equalisation added (filter) and that's how most headphone drivers are so it boils down to housing or enclosure to makeup for the deficiency in actual frequency response or sound. Ultimately you are the one who decides if you prefer the coloured sound or a neutral one. There is no right or wrong you are paying for it but convention and scientific way is a flat response so that others can be judged at the same criteria or standard.Hope this helps. http://www.testfreaks.com/headphones-heads...amic-dt-880-pro
  7. Hi chknbll, This is only my opinion basing on science and experience.Many audio virgins think that what is missing in sound quality is the price tag of a pair of headphones,more cost equals quality and technology.Because of business and marketing the truth is actually ignored and suppressed to impress the gullible.Research has been done long ago and the facts established,you can search online or buy books that talk about headphones or speakers and transducers as such. Does that mean all is known about the science of headphones/ hearing? Well research cost money and it depends whether a company wants to stay ahead of the game.Currently the main components which is the transducer or "speaker" which technically what it is are standard ,the big ones (40mm) and the tiny in ear buds.So the difference between them is the quality of maufacture,materials used (magnet material) and cosmetics or the packaging that give the impression of quality and luxury. I don't want to talk about the earbuds because in reality one cannot expect the optimum sound quality due to it's tiny size.Now let's come back to the big ones with 40mm diameter transducers or "speakers".In general they have a thin sheet of plastic (mylar) over the magnetic driver or in speaker terms the plastic sheet is the cone and magnet assembly, the voice coil and magnet.So it all boils down to construction or build quality and type of magnet.The cheap ones use ferite material,ferites are not metalic but have electromagnetic properties,in essence they behave like magnets have north and south polarities.They better ones are made or rare earth elements,I'm sure you have heard it in the news about rare earth material/supplies allegedly being controlled by main producer China that made Japan look towards exploiting/finding rare earth elements in their own backyard so to speak.Rare earth elements are the over 20 types of elements that you learn in basic chemistry and it is the mastery and technological use of them to make things that basic metal or iron/steel alone cannot possibly make a modern car engine for instance. The better transducers have what is commonly termed neodenium magnets what that means is that the magnet material contains neodenium which is one of the rare earth elements.See how important they become to headphone people? You may have heard of alinico magnets in conventional speakers of old.The basic advantage of these magnets is that they have what is commonly known as high magnetic flux or power to push or drive the cones that is to vibrate thus having greater efficiency and therefore improved sound output.Alinico magnets contain alluminium,nickel and COBALT which is also a rare earth element of which the USA has designated as STRATEGIC RESOURCE so it controls worldwide the stockpile of rare earth elements.You may like to know that cobalt is used in steel making, imagine steel plates for battleships and armour piercing artilery shells. It can make many "useful" things. Why is it called rare earth? Well because it is rare or not commonly found and the quantities are small or less in the earth as a whole.Nobody calls iron rare only diamonds which you know as rare and expensive. Our housing prices are increasing not because they are rare but controlled, an artificial lack or "rare" if you like.It's basic economics of supply/demand and greedy people take advantage of it. That's how the world works. Back to topic The construction and housing play an important role in the sound quality. You may notice that some housing are half dome and fully enclosed that is there are no holes or openings. Now these can have boomy base as the enclosure behaves like a resonating chamber as everything in this 3D world or universe resonates or vibrate like electromagnetic energy.Then there's the open back type or hear through ones which don't have a cavity or less of it behind the transducer.So open types sound "open" unrestricted feel airy. The rest of the construction is mainly ergonomic that is it follows the contour of the human anatomy in the case the part surrounding the ears and head for comfort and efficiency.The exterior cosmetics like syntethic leather trim and chrome/gold plating make you think there is a high tech transducer in there when like putting spoilers on commercial stock cars don't make them a Lotus or Ferrari sports car. Now come the most important info when it comes to audio.Since you say that it is the laptop or PC that you listen to ,everybody and now's the time for you to know that the PC is a noisy environment when it comes to signal to noise ratio.What that means is that the PC was never intended as the ideal piece of equipment to use as an audio device.What with noise radiation from 50 hertz AC supply to gigahertz digital signals floating around literally.But of course the marketing people say humans cannot hear beyond 20 Khz. so that shouldn't bother you but research has shown that higher frequency signals as high as 200Khz. can be felt by humans thereby giving the sensation of a fuller sound. Check the Stereophile magazine archives for the article.So in short there is more than a good pair of headphones for you to start enjoying music as the whole is the sum of it's parts. Remember this and you can make your way to audio nirvana. Good luck.
  8. Hi all, I came across this free and powerful PC scope and spectrum analyser with a new ZRLC meter. As you know a RLC is a Resistance, Inductance and Capaitance meter in addition it can also measure impedance.Although mesuring range is conservative but good enough for general use. If it was me I'll add a speaker testing and design module and it will become a killer application yes? Alfredo Accattatis an Italian PHD holder said he could have comercialised ver.2010 next 2.4 but decided not to because he has a passion for electronics and heart for diy audio hobbists. I loaded the beta 2011 version to see what is latest you may download the more stable ver2010 next 2.4. But I still think using beta 2011 ( I am adventurous) and if you give feedback he may do something about it in his SPARE time.He has to work for a living and it's free so don't complain. Documentation is minimal but it's intuative but he is compiling a manual so be patient as most of the help screen are blank.So you need to be familiar with electronics,instrumention and digital signal processing.But if you are a newbie this is a good time to learn and he has a forum to ask questions or help.But remember they are Italians not english speaking people so there may be something lost in translation. WARNING If you are using your fancy notebook PC,it is not recommended as most soundcard inputs can only take 1 - 5 volts maximum and you risk frying the sound chip or expensive soundcard. Like tube circuits with high DC/AC voltage. Better to use ( old ) desktop PC with a decent soundcard like Creative soundblaster or newer models.If you use standard 16 bit soundcard you will get 20 khz. bandwitdh which is sufficient for audio ( 20 -20khz.)But if you have 24 bit /192k soundcard then you get about 100khz. which is better. What you need is a soundcard interface as an attentuator and level setting with buffer because there are long cables etc.Although you can calibrate it in soundcard (software) it may not be easy.There is also a ZRLC interface articles but they are in italian but the circuit schematics are easily understood by electronic hobbist like yourself. Alternatively a cheap digital multimeter can be easier? Visual Analyser download- http://www.sillanumsoft.org/download.htm Edit: Download Translated VA doc. by diyaudio member of VA thread on pg.6-- http://www.diyaudio.com/forums/software-to...cr-meter-6.html PC soundcard interface- http://www.pmillet.com/ATEST.htm PS the soundcard interface is not cheap because of the true RMS converter ic AD536 so may you can omitt it and use multimeter( not true RMS unless buy more expensive one) but if you are an advanced hobbist you may prefer the convenience. Have fun.
  9. Hi all, Just saw this yesterday and thought you might like something new to do for 2011. Well this is just a standard hookup of an instrumentation amp ( 3 opamps-LME49990) and a high current buffer LME49600.Now these are National Semiconductors new line of high performane opamps designed for audio as most opamps are for industrial uses. The thread in diyaudio - http://www.diyaudio.com/forums/headphone/1...ifier-pcbs.html He is offering 2 channel amp pcb + power supply at US or CAN $20 combo only and partial kit at $98 but may go down as more people join in.But I think you can save a little if you source locally but if you don't want the hassle he says he's not doing at cost as last group buy he made a loss . Anyway I checked Farnell singapore ( they now renamed their site- 14 elements sg) PS. The pcb is smt (surface mount technology) so may be tricky for some people. LME49990 - $7.21 you need 3/channel total= 6 LME49600 - $13.70 at 1/channel total=2 subtotal = $70.66 before GST. Edit- Sorry,mistake in calculation ,now show correct amount. Looks like you may really save if you add $20 pcb + smt resistors + caps. You can do the math and it's not a cheap project.If I had my way I'll not use instrumentaion style circuit but modify the 3 opamps and connect them in parallel by doing so you lower the noise level like Nelson Pass' Pearl2 phono amp.He parallels 4 jfets so that will get 6db reduction of noise level theoreticallly. But bear in mind if you modify the amp it may not be stable so there's the catch. I will not use the supplied generic power supply but make a Walter Jung super regulator instead and that will move this amp in the real very high performance level also theoretical. Super regulator links: the most recent is the 2000 version.Be careful with the part selection ,use the recommended ones like PN2907 and not 2N2907 and LM329 voltage reference.If you can't get LM329 then use a 6.8 zener(noisy) or series other voltage ref. but costly,then of course there are cheaper alternatives. Edit- wrong part number X 2709 X previous. Super regulator is a challenge to construct from what I've read,if you are not up to it then stay with conventional type.Which is based on the same principle except with regards the refinements and complexity. http://waltjung.org/Regs.html There's one easy to read page titled opamp regulators ,see if you can search it. So just see the pics and test results made with a Audio Precision test setup.Quite impressive. But then again despite the claims I cannot vouch for the sound quality as it varies with individual's taste and experience. Welcome 2011. Cheers.
  10. Assuming you have a full time job and running an online audio shop and say you are bored and you want to share? Try sharing cheer and goodwill instead of sarcasm. Edit: You have your online shop and blog where you can share to your heart's content. Quite a lame excuse don't you think? http://audiohub.com.sg/blog-entries/a-new-home/ Please remember that what you put in writing here is "forever".Who is being juvenile? You seem to be an intelligent person but your ego is getting the better of you. EDit: Yes theory is just theory and real life is what you said but bear in mind that this real world don't care what's really happening when something bad occurs they want some "heads to roll" or take "responsibility".Scapegoat in short.so if you say ,they did this all by themselves (free will) and that's life or karma is not going to go well with the authorities.They only see only 3D realities,not philosophy or quantum physics. Do you think your customers will consult you if you say irresponsible things? The moderator has taken notice of you and in fact this forum has the proper section (Announcements/offers) for people like you to market your products but it is not enough for you that you have to"stick it in the face" so to speak here.Have you no morals or ethics? I shall not comment and indulge you any further. Happy and prosperous new year to all.
  11. Hi , It is obvious to people that what you are doing is "bill board" advertising with the attempt at replying to posts and not being helpful.If you visit tube diy sites at the begining or end of the article there is always a disclaimer alluding or warning that high DC/AC voltages is present and to avoid serious injury to your own person or equipment.Now this is to avoid being sued in the event that anyone who attempts such a project have been warned or advised and a reminder of the potential risks incured.As the saying goes "fools rush in where angels fear to thread". Imagine, heart defilibrators used in emergency hospitals are a few thousand volts to jump start a dead heart.What do you think it will do to a live,pumping heart? As to your revelation at Mingda factory claims that the technician pulls out tubes while it is still powered may indicate he is trying to locate a fault.I can assure you that is bad practice as most people who work with tubes and have read enough of tube/valve design books will point out real life examples of such actions that with certain circuit configuration can lead to excessive voltage to tubes that will lead to damage. Good way is power off and then pull out.If you assume this is harmless then it is "blind leading the blind".PS would you like to pull tubes like big transmiting ones like 211,845,805 at around 1000 volts? Now I do not object to your method of "marketing" for that is human nature but there are better or effective ways of doing it.Given what you saw at Mingda factory would I want to recommend people to use Mingda's products? It's like they say "don't go into the kitchen of a restaurent,after that you don't want to eat there" or "what you don't know will not hurt you".Best practices will always prevail. If you are operating a real or virtual shop ( online) and is sincere and you want to offer good and well designed products that are priced fairly, to genuinely have your customers at heart and not just profit margin then "word of mouth" is more effective than all the advertising in the world.It is the goodwill and trust/love that you engender and attract that is priceless, lasting or of long term benefit. It is your intentions that count.Try it you will be amazed. Cheers. Happy and prosperous new year.
  12. Hi, As a further expansion of the art of audio, here is a presentation by the ETF ( European triode festvial) held every year where tube artists gather and exchange ideas and do shootouts of tube equipment and present "new" research on all things audio. http://www.triodefestival.net/index.php?pa...8-presentations Lecture in 2008 by Menno Van der Veen , a well respected designer of toriodal output transformers and tube amps and author titled: The philosophy and application of observations. In it is a scientific explanation of the superiority of single ended amplification vs pushpull. It's in the low level signal details that single ended amps can "extract" vs pushpull. By the way his torodial output transformers did not make the final round (etf-2009) which was won by Audionote UK. So theory is theory but the art is really a black art,you need to read about the japanese tube masters to have a glimse of the magic, scientific or is it in the mind or senses? Very philosophical and deep.Low thd specifications of transistor amps is nothing, there is more unseen/undiscovered factors at work,for instance the human ear hearing is non linear yet the basis and foundation of electronic design is linear.What have we missed? Cheers.
  13. Hi, Most of the "kits" here are designed in China or Hong Kong i.e. they are adaptations (meaning they are not carbon copies as some details are omitted like phono,selector and even the types of tubes used originally ) of copies of well known tube preamps that audiophiles wish they could own but can't afford as it's use as headphone amp is not as popular here or asia plus salelability.Nonetheless they can drive a standard headphone. Just substitute the rca output connectors for headphone 1/4 or 3.5mm ones or include both with a appropriate switch so you can have it used as standard preamp.But take note that these amps can put out more signal voltage than what a pair of headphones need.... Koba at Peoples park shopping center 3rd. flr has some pcbs plus parts so go ask Wee Kok the son of the proprietor for the list of preamps like Jadis jp200 Marantz M7 Kondo Audionote M7 Audioresearch Matisse and many more. Price wise they cost around $38 - $40 each but some like matisse or Marantz M7 include the power supply section on the board but audionote m7 or jadis jp200 has separate amp and power supply so I don't know if the price includes both sections to complete the amp. Many people start off with a Marantz M7 where there are many positive reviews but it uses 2 tubes/channel some would find the cost of 2 small tubes not attractive as running costs matter but small signal tubes are not that scarry. Then there is the design part in terms of sound quality.As tube artists say less is more or if you are a single ended enthusiast ,by the way all /most preamps are single ended,then the less tube stages the better. So if you are a novice then a pcb with everything on it may be easy and less mistakes encountered or if you are more into the fine art of tube sound then separarate pcbs for amp and power supply is the way to go plus choosing the "right" part as oppose to most expensive or commonly used but good sounding parts don't come cheap as there is a "audiophile" label attached. I would recommend the Kondo audionote M7 as it uses only one tube per channel ( 12AY7) which you can find at Martin at Burlington sq. ground flr. square opposite Sim Lim sq.I don't know if the power supply is solid state ie. it has silicon diodes or the original design of tube diodes ( 6X4). For beginers there is the problem of getting a suitable power transformer for your kit as commercially available ones may not have the exact voltage like the audionote 200 AC volts where at Martin they may have 250V or 300V as preamp usage.So you need to drop the voltage by using resistors.All in all expect to spend "substantial" money but if you are knowlegable about transformers you can use off the shelf ones commonly seen at sim lim tower,of course you real estate or space and weight requirements will increase alot as you may need to connect them in series or parallel. Come to think of it you can download the famous audionote M7 circuit (old version use 5687 tube) foc from the net plus tube power supply and wire it point to point which is the "right" way to go instead of pcb, plus tube power supply and with the right parts can kill many commercial store bought ones.Do you know how much a real audionote m7 costs? There is one compulsory WARNING though as tube amps involve HIGH DC and AC voltages it CAN KILL. Although this fact is true begginners take the plunge anyway but if you are a tube virgin then get someone experienced to guide you or do it for you. Good luck.
  14. Hi , Googled the Shure e3g, what an exorbitant priced pair of earbuds,even the pdf broshure does not explain what technology or how it works.So secret that people believe the marketing.The specs say it is 29 ohm impedance just a little shy of the standard 32 ohm so this should not pose a problem to any well designed/proven headphone amp. Since I believe the Shure e3g is new the wires should be in good condition so that leads me to suspect the earphone jack on the cmoy or components may have come loose on the pcb.Check with your multimeter or visual inspection. Good luck.
  15. dacboy

    CK2III help

    Hi Andre, You are pretty smart with electronics ... what with that software scope...I myself have not been successful finding one on the net... mostly trial or crippled ones.But I have a 60 Mhz. scope on hand if I have tough dog problems like this. Now if I assume your soundcard is or has low noise performance,I'm looking at purely the 1 Khz. signal then the little wiggles at the top and bottom peaks of the sine wave is evidently the intermitant noise you hear and it varies from half cycle to cycle.Noise like this may be hard to trace but from what I mention about the input section of you measuring almost zero volts should tell you that that part is very suspicous.If I assume the resistors are all correct then my logic will have to assume Q5/6 may be faulty.Small transistors like that can easily damaged by insert them forcefully into the pcb,that is making them sit close to the pcb thereby stressing the leads to break from the silicon chip,the gold wire or maybe copper is very thin.so essentially you have a break but it may still be in contact with the pad so partial contact is made. Use your scope to probe Q5/6 one of them may give more distortion and the other one may see a perfect sinewave.I don't have to tell which one is bad right? Probe also the jfets 2SK74/SJ70 ...by the way these have stopped production but still availabe at Sim Lim tower. I normally assume the opamp is good which most times and seldom give problem.Yes it looks like it balance out the dc offset. R16 if you measure 900k ohm in circuit then it's close to the 1 meg value, yes you got it right. You can use dale resistors which are prefered by audiophiles but double check or measure them before stuffing into pcb. You can do it Andre.
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