Wednesday, August 27, 2014

Transistor Tweak

I have a McIntosh MC-2100 power amplifier I have been tweaking now since I purchased it new back in 1972. It has undergone some serious modifications including the replacement of all internal wiring and converting it to a true single-point ground scheme (that took a while) back in 1984. After performing that amount of major surgery, this amplifier sounded REALLY sweet and its purity has been locked firmly in my sonic memory ever since. As time passed, this sweet sound gradually faded and while it still sounded "good," it just lost that magic it had right after the wiring upgrade.

McIntosh MC-2100 Amplifier, Power Transistors on Heat Sinks

This generation of solid-state audio amplifiers used the TO-3 style power transistor sandwiched to the heat sinks in the usual manner: insulator between the transistor and heat sinks and screws holding the transistor to the socket.

Typical TO-3 Mounting Hardware Style 1 (screws not shown)

Typical TO-3 Mounting Hardware Style 2

Any well-respected high-end enthusiast will routinely clean off his/her interconnect cable and speaker cable connections with anti-oxidation cleaners; the contact resistance rises as these connections oxidize. That quality sound you once valued begins to fade in proportion to this corrosive effect. A quick cleaning treatment usually restores the music to its previous glory (tube pins and sockets suffer a similar fate).

Taking this contact cleaning thought another step further, I tried something not so drastic as to clean the contacts of these transistors (mine are soldered into the sockets), I merely loosened and re-tightened the mounting screws. You see, the screws are the electrical path for the outer case to the socket and the same oxidation can occur on these as they do on the interconnect cables and such other mechanical switch contacts. A simple twist of the screwdriver to loosen and another to re-tighten knocks off the oxidation enough to make a difference. Of course removing the screws one at a time and cleaning them as you would the interconnect cables is another (better) option but I was in a hurry just to see if my theory was correct.

I am elated to report that the glorious sound of the amp has again returned. The focus within the sound stage is as refined as it ever has been and the depth, width, and height are considerably improved beyond what I recalled it to be at its best. There is also an improvement in the subtle inner detailing of all instruments regardless of frequency and harmonic distribution.

Much like other simple mods I have suggested, this one is pretty simple to do and can change the way your system sounds with little effort. Make sure that the power cord to the amp is unplugged before beginning and wait an hour or so to allow the power supply to totally bleed down before popping off the cover. A screw driver, a wrench, a twist loose, and a twist tight is all that it takes.

The next time I schedule my amp for downtime (the main supply capacitors are starting to show signs of hum), I will indeed remove the screws and clean them properly. But for now, I cannot believe how just this simple fix has rejuvenated the sound of this amplifier. I would highly recommend having this don to your amp too.

Yours for higher fidelity,
Philip Rastocny

Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

http://www.amazon.com/dp/B00QFIAC3G

My other titles include:

Copyright © 2015 by Philip Rastocny. All rights reserved.
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Saturday, August 23, 2014

Pioneer Selling off their A/V Division

One of the first receivers I ever heard was a Pioneer way back in 1968 (a mere 44 years ago). A friend brought one back from Japan and set it up in his room; big, bold, and making a statement. Pioneer took audio (then stereo) and elevated it to the level of high fidelity cashing in on a quickly growing industry of stereo receivers. Previous business decisions were made in an attempt to turn around the profitability of this division (most notable the elimination of the Elite plasma TVs) and this one is the nail int he coffin.

But today, audio in all forms seems to be losing traction yielding to other technologies and Pioneer made an uncomfortable business decision, one that I am sure was not as easy to make as just a stroke of an accountant's pen. For example, record sales in general are down as is just about everything in the audio realm and many companies are feeling this same urge.

Business decisions are fine and necessary for a company to survive. Abandoning a sinking ship makes sense and with Pioneer's decision we see signs that soon there will be less and less quality mid-fi to lure people into the high-end. It's not that Pioneer's A/V sales were bad (over $1 billion last year), they just were declining (although their car audio business is booming, pun intended). Onkyo and Baring Private Equity now control the ship and I hope together they steer it to new heights.

What does this say about the mid-fi and high-end community in general? Are we a dying breed that will one day be relegated to antique stores, museums, and exotic collectors? Will your entire DSD collection be one day wiped by a simple press of the DELETE key? It makes me shudder to think.

RIP, Pioneer Audio and their high-end Elite line. Hopefully, the new owners will have the dedication to persist as other struggling audiophile companies today are. They all feel the pinch of change. It would be sad to see all of the great work Pioneer engineers created over their history lost forever falling prey to the dreaded but essential balance sheet. I believe Onkyo will be a good infusion to this new team of owners but time will tell.

This makes me recall a similar tales of companies gone by. R.T. Bozak, Crown International, Phase Linear, Fisher, Apogee and many, many others succumbed to a similar fate and I am sure more will fall in the future. But history demonstrates that others will rise up out of the ashes and carry on the torch - the Phoenix. Hey, maybe that would be a great name for the new products if they decide to drop the old Pioneer name!

I feel sad that my Pioneer PL-L1000A turntable has now made one more step to being officially called an antique -- but maybe that is a good thing! Just feeling a bit melancholy - even though the Denver Broncos at the moment are winning even though Wes Welker just took a cheap shot to his head.

Yours for higher fidelity,
Philip Rastocny

Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

http://www.amazon.com/dp/B00QFIAC3G

My other titles include:

Copyright © 2015 by Philip Rastocny. All rights reserved.
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Wednesday, August 6, 2014

Capacitors: All Things are NOT Created Equal - Part 1

When buying speakers or electronics, designers always begin a project with a budget and an idea of what can be done with that budget. In the lab behind the curtains, designs take on a very different look than what finally gets out the door. Bread-boarded amplifiers, cobbled-together cabinets, and recycled power supplies are common items jockeyed about in an engineer's inventory never seeing the light of day, at least from the consumer's eyes.

 Part 1 - The Budget

 An evolution occurs in an audio design where once a fundamental parts count is achieved, juggling the costs of these individual parts makes a difference in how the total comes in line with the budget. For example, the budget for a small 2-way speaker could look something like this (actual values vary but this is just an example to make a point):

  • 8" Woofer: 20%
  • 1" Tweeter: 10%
  • 2,500Hz BW-2 Crossover: 15%
  • Cabinet: 20%
  • Shipping box:: 5%
  • Misc. Materials: 5%
  • Labor: 25%
  • Raw Cost: 100%
  • Selling Price: 5 X Raw Cost

A similar budget is created for any piece of electronics gear with a far greater granularity but you get the general idea. What typically happens is that one of these items runs over budget so the designer must start juggling numbers to stay within the budget OR increase the budget (something the bean counters hate). So if the design must stay within budget, something has to give if the design is to make money. What typically is compromised first is the quality of the parts used in the design (what is on the bench rarely makes it into production).

 If the designer can make a crossover network for less and stay within budget, this is one option OR use cheaper drivers OR a cheaper cabinet. Sourcing alternative drivers while possible is harder to do if a certain sound is to be maintained and the price difference for a typical 8" woofer can range from $20 to $80 (4x difference). Sourcing alternative cabinets is an option, especially if cabinet resonances can be disregarded and price differences are similar (2x-4x). 

 But the cost of a quality capacitor or inductor can be hundreds of times higher than the least expensive form available. For example, a 2.2uF/100V Deuland Cast PIO is $443, a 2.2uF/600V Mundorf Supreme is $22.50 (about 20 times lower in cost), and a 2.2uF/100V non-polar electrolytic is $0.50 (886 times lower in cost). So the parts count can be identical but the cost for these parts can be adjusted so that the design stays within budget.

 But what do you give up for the lower cost?  A good analogy to answer this question is to look at the MSRP of new automobiles. All of them will go 70mph but why does the TATA Nano have a MSRP of $3,056 (the cheapest car built) and the LAMBORGHINI Veneno have a MSRP of $4.5 million (BTW, the last one of the nine built sold for $7.6M)? Is the Veneno worth 1,472 times more than the Nano? Well that is what the high-end is all about, right? And if you believe that the Veneo is worth it, then you are truly a hopelessly hooked audiophile like me.
The Lamborghini Veneno

So to build a Nano, one uses the lowest cost parts possible (here the non-polar electrolytic capacitors) and does not include much in the way of an audio system and for the Veneo cost is truly not an issue (here the Deuland Cast PIO capacitors). BTW, the Veneno comes with a hand-tuned custom-built Monster(TM) audio system and the Nano doesn't. So it is with audio design and the allocation of its budget that determines what is and is not possible. (Does your automobile go from 0-60 in 2.9 seconds? The Veneo does and the Nano doesn't!)
 
The Tata Nano

 Matching the links in the audio chain becomes as important as the budget to which this speaker is assigned. Again as an analogy, would you suspect to find the Monster audio system of the Veneo in the Nano? No. And why not? I am sure that this question need not be answered.

 The question becomes one of applying the right money to the right design to fit into the right system. One would not appreciate the $400 Deuland capacitor in a $100 boom box but even in this modest system one would appreciate a minor capacitor upgrade from a $0.50 non-polar electrolytic to something a little more esoteric at just twice the price.

 So now that you understand a little about budgets and how things fit into the overall audio chain, in Part 2 we will look at why it costs what it does to make a good sounding capacitor and what some of the major design considerations are.

 Related articles:
The Vishay 1837 Review and Modification
Bypass Capacitors
Mundorf Supreme Capacitor Review - Part 1
Mundorf Supreme Capacitor Review - Part 2
Capacitors: All Things are NOT Created Equal - Part 0
Capacitors: All Things are NOT Created Equal - Part 1
Capacitors: All Things are NOT Created Equal - Part 2
Capacitors: All Things are NOT Created Equal - Part 3

Yours for higher fidelity,
Philip Rastocny

Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

http://www.amazon.com/dp/B00QFIAC3G

My other titles include:

Copyright © 2015 by Philip Rastocny. All rights reserved.
Posted by at No comments:
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