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catman

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catman last won the day on April 24 2015

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About catman

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  1. G'day all, yes that is one of the issues. The overall design looks like it was derived from something much more complex with components removed to a bare minimum to keep it working! Regards, Felix.
  2. Humble pie time! G'day all, I'd like to think that I'm not stupid and my general comments on phono matters are truthful and technically accurate, but alas I have to admit that a commercially made phono stage that I once regarded highly and actually recommended, has turned out to be a badly designed POS! It plays well but a little technical investigation has revealed some major design shortcomings one of which could actually cause amplifier damage because of a significant DC offset on the output! Some amplifiers will happily tolerate this, but some amplifiers (like my own) will not! In fact this is how I actually became aware of this design problem! One of several I might add. It is just as well that this particular unit is no longer in production. Caveat Emptor! Regards, Felix.
  3. What are the audible signs of a stylus that definitely needs replacement? G'day all, this is a question that I've never really had a definitive answer to. As I generally don't keep tabs on how much use my stylus has had (time wise), I am looking for a definitive answer to this. With the Ortofon stylus 10 that I've just replaced whilst it looks fine with a simple x10 magnifier, and it sounds ok however I have noticed occasional bursts of severe playback distortion at times. Replacing that stylus today, all occasional playback distortion is gone, so I guess that old stylus had reached its 'use by' date, yet that isn't a definitive sign of wear, or is it? Any comments or thoughts? Regards, Felix.
  4. When do you most notice sonic differences during comparisons? G'day all, I've been playing lots of records of late using mostly my DIY op amp phono stages and they all sound great so for a quick comparison tonight I plugged in my Rothwell Simplex and had a listen, and immediately on stylus set down the 'different' and unstressed/musical sound of the Simplex was readily apparent, however after a relatively short time it sounded much like any of my best phono stages. That is curious. Acoustic differences and clues apparently are quickly absorbed and seemingly accepted as 'normal'. Regards, Felix.
  5. G'day all, yes it has all the 'looks' of a phono stage designed for broadcasting applications. As such it is bound to be very high quality! Leave it as it is, get it working as needed and enjoy! Regards, Felix.
  6. G'day all, this can be heavy reading, but is an excellent technical reference, and is recommended reading. Regards, Felix (vk4fuq). http://audiosystemsgroup.com/RFI-Ham.pdf
  7. The bass response of modern 'chip' amps. G'day all, I've had a new commercially made 'chip' based amplifier for a little while now which is excellent, however one little thing is slightly curious. With my old DIY (chip) amp I happily used an external active subwoofer with excellent results, however with this new amp the bass response, even with just the bookshelf speakers, seems much stronger than with my old setup and actually a subwoofer seems entirely unnecessary. Is this good bass response 'typical' of modern 'chip' based amplifiers, or is something else at work here? Regards, Felix.
  8. IC socket issues! Maybe things like this happen in these crazy days, but today one of my DIY phono stages 'just stopped working' for no apparent reasons and all the usual faultfinding achieved 'nothing'. Head scratching time! Then I happened to bump one of the op amp sockets and things suddenly jumped into life! A few checks indicated an intermittent contact(s) on that 'high quality' op amp socket! Mmmmmm. I always prefer to use good quality IC sockets when possible for obvious (faultfinding) reasons but I know knowledgeable people who suggest that sockets should never be used in any case. I wonder! Regards, Felix.
  9. The attraction of 'good design'. G'day all, whilst my general working knowledge of electronics is good, my ability to design stuff is limited to the very basic, simple block stages and the like. The design of a complete phono stage is quite beyond me, requiring quite a high level of technical understanding, practical knowledge and measurement ability. The are thankfully people out there who can. For this reason Andrew Russell of hifisonix is one of these people. His 'Simple, Accurate RIAA EQ Phono Amplifier' is a fine yet simple example of good design and it is rapidly becoming my favourite DIY phono stage design, and it impresses me at every listen! I have learned a lot from reading his various design articles, and it is obvious that his excellent design work shows through in the performance! I believe that he has another fully featured MM/ MC phono stage with excellent performance in the final stages of development, and that is well worth keeping an eye on! Reflecting on what I had personally seen over the years it is apparent that there is 'good looking' gear available and for sale, but sadly as I have seen, 'good design' is not necessarily a part of the product and I can think of a few examples of this, and that is a real shame in my opinion. Coming from a technical background, good design has always impressed me more than anything else! Long may that trend continue! Regards, Felix.
  10. Phono stages. Is it horses for courses, or just the nature of records? G'day all, years ago I had one of spoken voice/ music test records, and one thing that I'll always remember was the commentator saying, 'the tonal balance of records varies a great deal'. Ain't it the truth? I guess this is why no phono stage or even cartridge can sound perfect on 'all' records. Maybe this is a good case for using good tone controls. That being said, I do have certain phono stages that sound superb on certain genres of music and others likewise! Don't you just love the whole record thing? Regards, Felix.
  11. The transient response of phono stages. G'day all, I've probably raised this before in my musings, and of late I've been rotating a few of my better phono stages and one thing that can be noticeably different is phono stage 'transient response'. It is a term that is difficult to define (even for me), but perhaps it is a sense of excitement as opposed to a sense of 'sameness'. As it presently stands only two of my (DIY) phono stages have this 'exciting' quality, and that is my ESP P06 DIY unit, and it is a quality that I recognised with the very first P06 that I built many years ago and my 'hifisonix' design (a very good design with excellent 'real world' performance). I have always attributed it to the 'split' RIAA equalisation used in the ESP P06, of active bass equalisation and passive treble equalisation. Fully passive RIAA eq stages can sound very similar, yet to my ears the 'exciting' sound of the DIY ESP P06 is rather unique! I have always felt that 'interaction' of for example, active equalisation might be a possible reason, but that is probably a bit simplistic in all honesty! I guess that there should be some mysteries in this world! Regards, Felix.
  12. G'day all, just further to this general subject it looks like there are indeed fake and/or poor quality NE5534's out there and unfortunately I have a few of them, but thankfully I do have some 'good' stocks. Interestingly enough since replacing the suspect ones in my DIY 'hifisonix' phono stage, the sound quality has markedly improved! All this makes me wonder how many of us are using fake and/or poor quality devices in our DIY gear without knowing it and getting poor results as a consequence! Mmmm. Regards, Felix.
  13. Fake and or poor quality op amps? G'day all, this is an interesting one and I am starting to wonder if I have a bad batch of NE5534 op amps. I use them in one of my phono preamps and for no apparent reason I have had several unexplained op amp failures, and today I noticed something possibly a little odd, while all of my op amp stocks have typed/ printed ID's on them all of the failures have ink that appears to be 'faint' and surprisingly easy to rub off! Are fake or non genuine op amps a possibility? Regards, Felix.
  14. G'day mate, I have the circuit but I'm actually not sure! Its design is sufficiently unorthodox! It is a very interesting and good sounding design! Regards, Felix
  15. Doing it 'right'. G'day all, back to musing! After reading those excellent hifisonix series of articles on aspects of RIAA and related things, I find it and indeed a trifle 'cheap' that many manufacturers of 'well regarded' phono stage designs, especially of the common full feedback op amp design approach, are not properly designed, and do not properly conform to the true spirit and intent of the RIAA specification, and to be honest although many of mine are in this category, and simply for this reason I actually don't feel like using them anymore despite sounding very good! I guess that is the old technician 'perfectionist' side of me coming out. Thankfully a few of my phono stages 'are' designed properly and also sound good! I guess this is part of the argument of what actually 'sounds better' regardless of design aspects. I can see merits in both sides, however because of my past technical training, I always tend to err on the side of technical factuality! Regards, Felix.
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