Sunday, April 13, 2014

Onkyo P-3000R Preamp Review

Back in the 1980s, Onkyo introduced a minimalist all-discrete transistor stereo preamplifier that raised eyebrows in the then high-end community. Called the P-303 Ultimate Stereophonic Preamplifier, this single-ended preamp used a circuit topology that pretty much doubled the parts count by creating two parallel-symmetrical amplifier stages in each channel, one consisting of an NPN design and the other a PNP design (four amplifiers total in this two-channel preamp). Then, each channel kept its individuality by maintaining an end-to-end dual-mono configuration but sharing a single E-I transformer power supply (obviously a last-minute cost-reduction measure). Separate nickel-plated low-impedance solid copper busses evenly distributed a single-point ground and +/- power to this unique circuitry.


P-303 NPN-PNP (aka DIDRC) Layout

The outputs of these two stages were then summed via a simple R-C network back into one channel. The theory behind this design was that any distortions created at the transistor junction of the NPN topology would be inverted PNP topology and therefore cancelled at the summing point. Interresting design approach and one that was improved upon in two subsequent models, the Integra P-304, P-306, P-308, and P-388F with the P-388F being the last model to use only discrete transistors in its design. Subsequent models used integrated circuits instead of descrete devices.


Onkyo Integra No-frills P-303 Stereo Preamplifier

Another feature of this no-frills preamp was that it used Mu-metal as an RF/EMI shield ver the entire top of the preamp and the bottom of the phono-stage. Mu-metal is expensive and used by the big boys (like NASA) to improve the noise floor in highly sensitive scientific instruments and shield them from stray interference. With a sweet all-wood cabinet and a single-supply but dual-mono layout, this preamp made waves.


P-303 Exotic Mu-metal Shielding

Its shortcoming was that it only selected two high-level inputs, a tape loop, and MC or MM phono cartridge (yes, it did have a similar circuit topology for the additional gain stage of the MC pre-preamp).


P-303 Spartan Inputs/Outputs

No one else ventured into this intense esoteric realm and after a few years the design faded into audio obscuredom...until 2013. Onkyo revived this fundamental design, improving it again, and resurrected it as the P-3000R.


Onkyo P-3000R No-frills Preamp

Now the P-3000R does not feature the Mu-metal shielding of its predecessors, does not have the beautiful rosewood cabinet, and it does not provide a well-designed moving coil pre-preamp, but it does retain the dual-mono NPN-PNP circuit topology and incorporate a few modern updates like a torroidal transformer, remote control, and alphanumeric display. Its limiting factor is that it is still a mostly single-ended design like its famous P-303 predecessor (it has one balanced input but no balanced outputs). BTW, Onkyo coinded the abbreviation DIDRC (short for Dynamic Intermodulation Distortion Reduction Circuitry) in 2013 to describe its unique NPN-PNP topology and its contribution to the improvement of solid-state reproduction of sound.



Toroidal Transformer for Analog Section, E-I for Digital Section

I owned a P-303 back in its hayday and found it to be every bit of what it was touted to be. But as time marched on, the unit and I parted ways not by choice but by circumstances. Needless to say that when I learned of this circuit topology being reintroduced I was anxious to hear its improvements.

This unit now selects from three high-level inputs, a tape in/out loop, two optical inputs, two coaxial digital inputs, a USB input, an AES/EBU balanced input, plus the phono stage making it a really nice addition for people with a lot of gear to manage. With built-in 32/192 Burr-Brown DACS, it is a real steal for its price.


P-3000R Rear Panel

After only four hours of play time, this unit settled in and sounded wonderful. As I recalled, the phono section was stellar being so low in noise that I could have been convinced that they still used the Mu-metal shielding. High-level inputs were also dead quiet making this unit non-contributor to any hum or noise that your system may have. However, know that when the unit is turned off, the preamp chassis itself is not grounded to the power cord and can therefore cause a bit of hum to the amplfiier (that is, if you leve it powered on all the time as I do).



P-3000R Under the Hood

After about another 100 hours of play time, the sound again smoothed out even more and transparent is the best word I can use to describe its change. The NPN-PNP topology is carried over to two discrete output stages meaning that unlike many high-end manufacturers who use the same discrete channel to drive two amplifiers from their two output jacks, the interaction between varying amplifier input impedances and the preamp's ability to trive them uniformly is completely resolved by using these two separate stereo driver stages. Individual output level controls allows you to make minor adjustments to the gain differences between amplifiers providing a master-volume level that properly drives both amplifiers. An optical digital output is also offered providing selectable 32, 44.1, 48, 88.2, and 96KHz sampling rates.

This peamp also features a discrete headphone amplifier using this same NPN-PNP circuit topology. A separate volume control is also provided for the headphones and an auto-mute function is applied to the amplifier outputs when headphones are connected (a nice feature). The separate colume control allows you to listen to your headphones at whatever level you desire and then when you unplug them the amplifiers do not overpower you or blow out your speakers.

The Sound

With my OPPO BDP-105 is connected to the CD input, I put in the C-Major Blu-ray version of Mozarts's Magic Flute. This is an amazing 2013 production comperable to that of a first-class Cirque du Soliel feature. The sets were poised on a floating, rotating stage with towering bridges and pyrotechnics. The orchestra was superbly recorded as were the voices although I personally prefer more emphasis on the percussion section. Voices were absolutely fluid pulling you into the characters even moreso than any other transistor preamplifier I have ever heard. This preamp used in the "direct" mode is strikingly neutral. Adding the tone controls does color the sound just a tad so I prefer listening to it with the tone controls bypassed from direct mode.

The bass was deep and dynamic again with a balanced and neutral signature. Crescendos and pyrotechnic bursts routinely resounded in my listening room providing realism and depth that sucked me into the storyline of human nature without noticing that the sound is what was making the performance so enjoyable.

A switch to another Blu-ray (Pacific Rim) smoothed out the glariness I observed while listening to the OPPO directly driving the amplifier. Even my old trusty Dared MC-7P preamplifier was not able to do what this preamp does despite  its fine complement of NOS Mullard tubes.

The phono stage is connected through my pre-pramp (a hand-built solid state design based on this same NPN-PNP circuit topology but a true dual-mono, dual- toroidal supply design). IMHO, this is the best part of the P-3000R for it has the ability to lower the noise floor of analog vinyl to a level you may find hard to believe. Even recordings that I would consider not as good as my reference few sounded more accurate and more revealing than ever before. But with a really fine pressing, such as the cirect-to-disc M&K RealTime Records #RT-101 For Duke, Scott Hamilton breathing into the reeds of his sax was just as I recalled it while sitting in the first row center at the old historic Paramount Theater in Denver. Back in the early 1980s, I had season tickets to the Dick Gibson Jazz Concert series and Scott was one of Dick's routine favorites on the billing. His uncanny smoothness and flawless execution made a permanent impression of how a sax should be played forever in my audio memory. I feel like I am there again listening to this piece although in a much smaller hall.

In closing, the DIDRC topology allows you to hear things that other designs do not, something to remember when auditioning gear. It has a very different sound that to some at first may seem unnatural. What you percieve is not this preamp's unnaturalness but how almost all other solid state preamps color the sound. Once you setle into this difference, you begin to hear its other striking qualities and effortless dynamics.


Summary

Although lacking the midrange warmth of fine tubes, this preamp is definitely not sterile or metallic as most solid state preamps are. It is sort of a jump between what the best solid-state preamps do well and what the best tube preamps do well. Overall, I would still prefer lsitening to a well-tubed Audio Research but the differences on all but the best high-end systems are not that dramatic and for most these differences will not be worth the additional cost.

This is a really sweet preamp that does a lot of  things spot-on right. First, it is dead quiet (a must) and second it is extremely neutral (also a must once you climb that high-end ladder). Using this unit in your rig will most likley give it some life that you did not realize you had. If you are considering a best-bang-for-the-buck piece of high-end gear, seriously consider buying this.

Is this the best solid-state preamp made? No. Is it a seriously good solid-state preamp? Without a doubt. and one that you will be proud to own. Even if you are the type of person who loves to modify gear, this one will respond really well to tweaks like capacitor rolling.

Monday, March 31, 2014

Logitech Harmony 650 Universal Remote Control Review

As your collection of audio gear grows, there comes a time when you get tired of dealing with the pile of different remote controls on that table next to you. Have you ever wanted just to listen to music or watch a television program and could not find one of them? The frustration can be overwhelming and the clutter is something I personally despise.

So I decided to finally do something about the clutter. But where does one start? Organization? You bet! I sat down and created a short-list of what features were important for me to get based on my previous experiences with poorly-designed universal remote controls. The "must have" features I came up with are:
  • Learning mode for atypical control codes (use the existing remote to train the new remote)
  • Long battery life (possibly rechargeable)
  • User friendly and intuitive (MUST have an ultra-high spousal-approval factor [aka SAF])
  • Small, preferably controllable from one hand
  • Does not forget its programming when quickly changing batteries
  • Capable of controlling both IR and RF gear
  • Easy to program
  • Easy to access repetitive functions
  • Does not require any device to be network connected
  • Best bang for the buck (read under $300, preferably under $100)
While some allow computer programming, this ability to me is optional. And although I need it only to control IR devices, many newer products are RF controlled and it would be nice to plan for the future. With this shopping list of features in mind, I decided to look into what was available.

The problem with remote controls is that there is no standard. Unlike HDMI, USB, and other interconnects, remote controls use a variety of digital command sequences based on a slurry of methods prepared by a variety of engineers from a plethora of manufacturers, none of which are involved directly in the industry to which the remote is used. For example, one manufacturer creates a remote control device that is used on a toy car and this same electronic device is used on a television or personal media streamer without conflict by just tweaking a design parameter. Convenient for equipment designers, yes, for consumers, not so much.

And there seems to be no relief in sight...or is there. Logitech, a company who first entered the consumer market with its computer mice, has grown its product family in many ways, each with its successes and failures. But this market seems to need someone to take the reigns and get a hold of simplifying complicated issues and they have done a decent job. After evaluating the higher-end offerings, I decided to spring for their more budget-based product, the Harmony 650 available for well under $100.

This remote offers PC-based programming and an online tool that allows you to research which devices it can control, something you really need to investigate before buying anything. And with all of my gear on their list, I was at least confident that training it from the manufacturer's remote would not be necessary (although it can do this too).

I was frustrated after the first software installation and control setup since it frankly did not program the remote as I had instructed it to do, but after removing, rebooting, and re-installing the web app, all went well. (BTW, to reset this remote, remove one battery, hold down the "All Off" button, and reinsert the battery. This will enter SAFE MODE on the remote allowing it to wipe the current training and relearn everything.)

What I really liked about this remote is the four one-button tasks. Say you get up early one morning and have not drank your favorite morning beverage reviving your weary eyelids and encouraging your sluggish body to move. The Harmony 650 has a button labeled "Listen to Music" and once properly programmed it will allow you to do just that with the push of that button. What a concept! Now, a word of caution, you must keep the remote pointed at the gear for a while so that all of the commands can be executed at the time required. For example, my OPPO BDP-105 takes its time getting to the HOME screen so the remote control understands this and pauses the appropriate amount of time before telling it which source to select. Brilliant! High marks for the Logitech's attention to the SAF.


Full-Color Logitech Harmony 650 Display and Four Task Buttons

However, and this is a big however, this remote forgets its programming functions. Yes, you heard me correct, with the next day's use, this remote control forgot how to turn everything on. While it did recall how to switch individual devices on/off, doing so from one of the four-button tasks did not reliably work. Use of the HELP button did resolve the issue for the moment, but after another all off/on cycle, back to the same old forgetful behavior and I have to retrain it...again, and again, and again. I don't know about you, but having to reprogram a remote almost every time you use it is not why I buy a universal remote control.

On the rare occasion that is does remember to turn everything on properly, accessing a device to perform another function (like changing the source of the OPPO) forgets the mapping to the volume control on the preamp (duh!). So going back-and-forth between devices becomes essential but again for a remote of this level it should not be unnecessary.

So, the bottom line is this: the Logitech 650 has the right idea but the sample I received did not work as advertised. For this reason, I am going to give these folks the benefit of a doubt that for some unknown reason I received a lemon (lemons happen). However, for this same reason I cannot give this remote a glowing review.

Until Logitech steps up to the higher-quality-control plate, I would look elsewhere for an under $100 universal remote control.

Yours for higher fidelity,
Philip Rastocny 

I do not use ads in this blog to help support my efforts. If you like what you are reading, please tell your friends and remember to reciprocate by purchasing some of my very affordable works at Amazon.com. My titles include:


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Monday, March 17, 2014

On Esoteric Wire...


Conductor types and purity have often been a topic of hot debate where on side endorses use of exotic materials and another snubs up their noses at any audible benefit. To set the historical record straight, below are some notes that should help you understand why this topic seems to rear its head so frequently.

Back in the early 1970s, someone questioned one of the most overlooked and common components in every audio system: the material used for wire or conductors. Since once cannot escape wires in interconnects, speaker cables, speaker voice coils, phonograph cartridges, internal chassis wiring, and circuit boards, this seemed to be a logical area for investigation. If there were an advantage to moving to a different material, there were a diverse number of places it could be implemented. A few companies introduced speaker wires and interconnect cables in response to this curious question touting this or that advantage because of this or that feature. In reality, most claims were fruitless and sheer marketing hype.

This doesn’t mean that there were not differences between conducting materials – there are drastic measurable differences – but when marketing spun the assets of these features they turned out to sound more like snake oil than science. After a prolonged learning curve, these marketing goons learned what did and did not work when pumping up the benefits of their products and today buzz words associate fair, good, better, and best conductors. (BTW, I love these goons since they are the people responsible for advancing sales and therefore the advancement of the high-end itself, but often question their choices of words or stand on reasoning.) Before jumping into the fray of these buzz words, let’s review a bit of historic around conductor materials.

When wires were first needed, scientists analyzed which pure materials (not alloys or processed metals) had the least opposition to electrical flow and in the order of their “conductivity” (electrical resistance per unit length) are from best to worst are: silver, copper, gold, aluminum, zinc, and nickel. So the best conductor was silver with copper a very close second. Two characteristics of silver eliminated it from the desirable material list since it was expensive and it easily oxidized. Copper was therefore the number one choice (see a highly descriptive resistivity table for all electrically conductive elements in the periodic table at http://hyperphysics.phy-astr.gsu.edu/hbase/tables/elecon.html#c1).

With the introduction of computers and high-speed electrical signal technologies, coated copper materials were developed to improve high-frequency characteristics. Called “wire-wrap wire” this coated copper also came in a new manufacturing process introduced in 1975 called OFHC (oxygen free high conductivity). Here, oxygen normally encountered in is production is eliminated from the extrusion process thereby improving its conductivity. Another refinement also improved conductivity by eliminating normally-encountered impurities (called high-purity or HP). Again, audio manufacturers swarmed behind this new process and introduced a variety of cables featuring this new type of copper.

Recently, a further copper refinement process was patented by Professor Ohno of the Chiba Institute of Technology in Japan that reduces the number of fractionated crystal structures and other impurities. Termed the Ohno Continuous Cast (OCC) copper, this metallurgical process uses a heated mold for casting and extruding, with cooling taking place in a separate process. The result is ultra-high purity copper with a larger crystal size.
Copper Type
Oxygen Impurities (PPM)
Hydrogen Impurities (PPM)
Traditional (TCP)
200-500

OFC
10
0.5
LC-OFC


OCC
5
0.25

With these results, the OCC process creates "ultra-pure" (UP), also known as “ultra-high purity” (UHP), copper and the abbreviation for this material is UP-OCC. (See http://www.copper.org/publications/newsletters/innovations/1997/12/wiremetallurgy.html for more information on current high-technology metallurgical manufacturing processes for copper.)

Oxygen Free Copper (OFC): Oxygen free copper was developed in Japan around 1975 as it became increasingly apparent that sound quality was related to the quality of copper and the processing used during cable manufacture. OFC is produced is a carefully controlled oxygen free environment resulting in a significant reduction in oxygen content (10 ppm). There are fewer crystal boundaries in OFC which results in much higher performance than TPC where the numerous crystal boundaries cause a degradation of the audio signal.

Linear Crystal Oxygen Free Copper (LC-OFC): In 1975 Hitachi improved the OFC process to further reduce impurities and crystal boundaries. The patented LC-OFC process developed by Hitachi re-heats the copper following extrusion which reduces impurities between the crystal boundaries as the copper crystal expands. This in turn leads to a longer overall crystal length. A typical crystal in a 1mm diameter LC-OFC conductor is 130 mm long which can be compared to typical crystal length of 4mm long in TPC conductors.

Ultra High Purity Oxygen Free Copper (UHP-OFC) is processed much in the same way as OFC but is also subjected to a further Zone Refining process (developed by William Gardner Pfann). With Zone Refining the purity of the copper crystals is increased by drawing a narrow molten region of a crystal. This molten zone is moved along the crystal (in practice, the crystal is pulled through the heater). As the molten region melts it leaves a wake of purer material solidified behind it. The impurities concentrate in the melt, and are moved to one end of the conductor whilst it is being drawn.

Ohno Continuous Casting (OCC): In 1985 Professor Ohno from the China Institute of Technology developed his patented method for the extrusion of a grain free copper wire. When a pure metal solidifies, its crystals grow in a specific geometrical pattern (typical to that metal) emanating from a nucleus, rather like the dendritic growth pattern of a tree. The size of the metal crystals grown can be varied by repeatedly annealing metal such as is done in the LC-OFC process. The structure of a strand of copper may be likened to that of a bag of sugar. Every grain of sugar has a crystal boundary. In a conductor, these crystal boundaries (potential barriers) act as a non-linear resistance to the flow of electric current. It follows that, the fewer the boundaries, the less the effect there is on an electric signal as it propagates from one end of the conductor to the other. The Ohno Continuous Casting method re-heats the extrusion as the molten copper is forced out of the mould and very slowly and gradually draws the grain or crystal down the conductor's length, creating a 'single crystal structure'. The typical crystal length of OCC copper is more than 200m.

So what’s the conclusion from this? In 350BCE, Aristotle wrote that women have fewer teeth than men and everyone did not question Aristotle because…well he was Aristotle, someone much smarter than most ever would hope to be just do not question these sort of things. But one day, someone got a brainiac idea, “Let’s count them!” What a concept. And sure enough, men and women both had the same number of teeth proving that even the great Aristotle could make a mistake. WOW! This means that even the brightest minds can learn a few things since their followers are taught to blindly do what they were told…until someone doesn’t. This is how advances are made – by questioning authority and finding out if what was once believed to be true still is - or is not.

Technology advances every day and sometimes several times a day. Our understanding of the world and how it works constantly evolves and with it should our reasoning for accepting old facts. What was once understood by one set of physical laws will always change once our understanding of these laws advances. It was once believed that the world was flat and the earth was the center of the universe. Anyone who disagreed was considered at the least off his/her rocker and at the worst a heretic and put to death. Skeptics have a purpose in keeping those of us who wish to investigate our changing understanding in one word "honest." Truth must prevail but even skeptics can be biased since they adhere to what they know – which may be an old understanding to which they unquestioningly now regurgitate the words of their teachers.

What I am trying to say is this: keep an open mind and even though the reason someone states that this is why something like wire sounds better than this other conductor, it is the goons who write the words you read (or even the idea maker her/him self) that may not be quite right. This does make the advancement any less justified; it is that we as human beings always struggle explaining what is going on with a new discovery of change. One day, Einstein, Stephen Hawking, every skeptic, every critic, you, and I will all be proven wrong. It is inevitable; all we need is more unconstrained time and open-mindedness for future generations to clearly understand why.

The best position you can take is that of neutral; neither for nor against but completely open minded. You count the number of teeth, you listen to the differences, and you make the choice. Don’t let biases influence your decisions and a better sounding system can result. Give that linear-crystal wire in our tonearm a shot, give that interconnect cable or power cord a try, and give that new CD player a go. All you can do is be wrong, and what’s wrong with that? No one ever advanced anything without making a few mistakes. Go ahead: fail and learn something new about what does not work. Then, try again.

Yours for higher fidelity,
Philip Rastocny 

I do not use ads in this blog to help support my efforts. If you like what you are reading, please tell your friends and if you are so inclined, buy some of my work at Amazon.com.  My titles include:



Thursday, March 13, 2014

URL to Bozak B-199A Thiele-Small Parameters

Some of you have requested information about T-S parameters for the Bozak B-199A woofer. Below is a link to the only site I know of containing this information:

http://petoindominique.fr/php/mysql_listehp3.php?marque=BOZAK

While the data is incomplete and uses many calculated values, until another source is found this is it.




Yours for higher fidelity,
Philip Rastocny 

I do not use ads in this blog to help support my efforts. If you like what you are reading, please tell your friends and if you are so inclined, buy some of my work at Amazon.com. My titles include:


·  Extreme Audio 1: House Wiring·  Build an Extreme Green Hot Water Solar Collector
·  Extreme Audio 2: Line Filtering·  The Extreme Green Guide to Wind Turbines
·  Extreme Audio 3: Chassis Leakage·  The Extreme Green Guide to Solar Electricity
·  Extreme Audio 4: Interconnect Cables·  Meditation for Geeks (and other left-brained people)
·  Extreme Audio 5: Speaker Wires·  Althea: A Story of Love
·  Extreme Green Guide to Improving Mileage·  Build an Extreme Green Raised Bed Garden
·  Extreme Green Organic Gardening·  Build an Extreme Green Rain Barrel
·  Extreme Green Organic Gardening 2012·  Build an Extreme Green Squirrel-Proof Bird Feeder
·  Build an Extreme Green Composter·  Extreme Green Appliance Buying Guide