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John Warren

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John Warren last won the day on October 4 2014

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    Engineering-Audio, magnetics, materials for electronic and magnetic applications, engineering models and simulation, SPICE, MATLAB, FORTRAN, acoustics, complex algebra, physics of sound, microphones, vintage audio, loudspeaker design, amplifier design, McIntosh amplifiers, discrete semiconductor devices.....and movies including silents, foreign and indies.
  • My System
    12" Utah Tri-axial drivers mounted in LRE bass "reflex" enclosures.

    Sony Superscope FM only

    Lafayette Solid State Stereophonic Integrated Amp

    16 GA Lamp Wire

    Koss Pro 4AA

    Technics SL-QD33

    CD Player:
    NAD 325i (modified)

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  1. The unity coupled transformer offers improved performance for CL-B vacuum tube operation only. CL-B amplifiers are somewhat higher efficiency than CL-AB.
  2. High BP can have nothing to do with weight. I recall a statistic that ~20% of the people on BP meds are at a good weight (i.e. BMI <24).
  3. It's dB (capital B for Bell as in Alexander Graham).
  4. John Warren


    A1C is the gold standard, most docs will prescribe an A1C if a couple of 12h fasting BG ratings are 105-115 (at least that was my experience). The correlation coefficient between BMI and A1C for the 50+y/o crowd is basically =1.0 so if you're heavy or obese you're most likely prediabetic or diabetic. To your point, you can live into your early 90s with all sorts of metabolic issues. I've got family members there now. And they're depressed, immobile (really crippled), fatigued, constantly panting and vision impaired. And that started 10-15 years ago. Not saying I won't experience same fate but if there's any opportunity to avoid it, I'll try. Genetics loads the pistol but it's lifestyle that pulls the trigger.
  5. John Warren


    In the meantime, researchers are still trying to figure out the causes of obesity in the USA.
  6. John Warren


    the health experts...
  7. John Warren


    And more along those lines...
  8. John Warren


    Shown below, the reason nearly 40% the US population is obese and we're in a T2D crisis in this country. They want you sick.
  9. Yes, I know where you're coming from. Even guys I know with T2D with A1C in 7s and on meds eat like they're teenagers. Oh yea, I love all forms of carbs, a classic carboholic. As Monty mentioned, I really don't miss them although it did take some getting used to. The wife was never really a big carb type which has been very helpful. What's been interesting is I've upped the red meat and expected to see a bump in the cholesterol numbers but nothing yet. Still working at 74? I honestly hope you enjoy what you're doing! Agreed. Not sure it's reversible either but we shall see. That said, thank you all for the words of encouragement! The other "trick" that's been working for me is making the morning run real early, like 6:30AM and making it a short duration, low preperation thing. I can do about 2.8mi. in 35min so it's no real time killer and easy to implement. Get up, coffee, read WSJ, NYTs (online), dress in running outfit and just go.
  10. For those of you struggling with sugar diabetes, a story. I've retired from full time engineering work about 6 months ago. Devoting a ton of time to amplifier design. One health issue that's always hassled me was blood sugar levels, A1C numbers hovering between 6.1-6.3%. Wasn't obese but always in the 25-27 BMI range. I'm 65y/o. I don't want to get T2D, it effects vision, hearing and motor function not to mention hammers the immune system. About two years ago, I went practically no carb. And, after about 6 months of that. dropped 30 lbs. In my little world, no carb means no pasta, no rice, no grains, no breads, no sugar and no to most fruits. For many people it's very restrictive and given this stuff's in everything, difficult. For me it was an experiment. Basically, when you come to the realization that white bread or whole wheat bread or brown rice or heart healthy plain oatmeal all turn into a gelatinous, sugar-rich "mass" in your gut, you start to get the picture. And don't take my word for it, just get a BG pin prick monitor and measure the results after eating say a cup of plain, "heart healthy" oatmeal with a bit of cinnamon and 1/2 a banana. There's NOTHING healthy about a spike from 102 before to 155 after, it's damaging and boosting the average BG levels. Not good. After about 18 months (15 Oct 2022) of no-carb living my A1C was 6.0, a small trend towards better but nothing to get excited about. Hence, no-carb was only part of the solution. I was eating lots of meats, vegetables, nuts (I'd even strip all the cheese and toppings off pizza and toss the pie!). Greasy stuff, except for processed meats are ok however. New strategy was needed. With a BMI of 22.5 thanks to no carb and a good EKG, in July I started running each and every day. First just to the end of the street, then a wee-bit more until about three months ago I was able to jog about 3mi each morning. Today, I can run at full stride over the same route. Many changes occur in the body, it transforms. Last week, I had a physical so some data share: The takeaway for me was it took three changes to get to a normal A1C 1. No-Carb enables weight loss 2. Weight loss enables running 3. Running lowers average BG levels Even today, my 12h fasting BG isn't great at 115 BUT after a run it drops to low 90s which, averages out to good A1C numbers (A1C is a 3 month average). That all said, there's hope if you want to reverse the trends. It's no easy but if I can do it, any clown can.
  11. I used the polypropylene orange drops (715P series) to replace the American Radionics foils. Tubes were new EL84M Sovteks. I thought the amp sounded respectable.
  12. Sovteks have been available for some time. Purchased 4 5AR4s, 10 12AX7s earlier this year. Just purchased a quad of EL84Ms too, supplier as 90+ is stock. So much for the Russian import ban.
  13. On the rectifier replacement, the 12AX7 filament string should read ~ -72VDC without tubes and with all four plugged in drop to -55VDC. If one tube socket is dodgy the whole string is out of commission and none will light, they're in series. It's not uncommon to have the original 12AX7s in these amps, they last forever. They were shipped with Telefunken. That got a chuckle out of me!
  14. The first place to start, assuming the power supply transformer is ok. is to pull all the tubes and go after the three electrolytic multicaps, all three need to be replaced with either replacements (Hayseed Hamfest does a nice job) or discrete assembilies under the chassis. Don't bother "reforming" or some other foolish thing. One must first get all the DC rails up to snuff. Replace all the carbons with ceramic compositions then get rid of the selenium rectifier. These amplifiers are very straightforward to service but can also be a ticket to an early grave so ground your chassis and check the fuse first before you go in. Updated link. Scott 222C (ipage.com)
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