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Monkeyboi

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Monkeyboi last won the day on May 17 2014

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About Monkeyboi

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    D.I.Y. Audio Enthusiast

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  1. My comment was a generic observation of the internet and not specifically aimed at anyone (I've yet to name) or about jfets. Indeed I have used jfets in pre-amps and the front end of power amps as well as RF gear dating back to the 1970s so they are devices that I would like to think that I have some degree of familiarity with. In many decades working in the industry I'm yet to find a datasheet or reference book from a semiconductor manufacturer with blatantly obvious technical data errors beyond the odd spelling or grammatical errors that somehow slipped through the p
  2. Hmmm.... 3% distortion is IMHO pretty high. Easily audible to most. I guess it just goes to prove that measurements do matter. Cheers, Alan R.
  3. Hmmmm... there sure is some fugly gear pictured here. Perhaps better listened to in a dark room or with the eyes closed? Cheers, Alan R.
  4. The internet is an amazing source of information. Unfortunately not all of it is true. There's one hell of a lot of misinformation being thrown around with zero accountability for potential consequences. Like some of the electronics channels where the vloggers / presenters have a very distorted and erroneous view on basic established electronics concepts. However no matter how often you bring the errors to their attention the BS continues. Dare to challenge their assertions and risk incurring their wrath. Hey but 100k+ subscribers can't be wrong - or can they? 🙄
  5. Apologies guys. I got side tracked with a few other projects and a number of repairs for some SNA members. Nothing to really add since the d.c. offset mod, but expect if you are building from an original kit of parts to have tantalum capacitor failures. The best solution is to simply buy new ones and heave those old ones out. The old ones fail short-circuit but may trap a few players as some of these old tag tantalums will test okay out of circuit on your LCR meter but will fail the leakage test when a voltage approaching their working voltage is applied. Happy to an
  6. It depends mostly on the type of resistor. In the ESP05 improved PSU the 10 ohm resistors shown are cracked carbon film 1W types. When overloaded but not to the point of total destruction the thin layer of carbon can develop microfine fractures which can alter the resistance when the resistor is hot and dissipating heat. This can potentially introduce minor changes in the resistance thus creating additional noise when current flows through it. These carbon film resistors have brass end caps which are mechanically attached to to the carbon film which is bonded to the ceramic
  7. Unfortunately the medium wave AM broadcast band it prone to interference especially in the modern world of switch mode power supplies (SMPS) which have infiltrated almost every appliance. Most LED lighting uses a SMPS instead of transformers the halogen incandescent bulbs we used to use. Cheap and nasty ones or faulty units can cause a lot of interference. SMPS generate a lot of unwanted RF which is usually well suppressed in good designs, but if one of the EMI filter parts fails the power supply can radiate considerable levels of RF pollution causing havoc with other devices li
  8. Possibly a trace of pressing mold release compound (no, not the fungus type)? Annoying but be thankful the music part of the playing surface is pristine. You'd think that over half a century of pressing LPs the manufacturers would have it down to a fine art, but alas it's all about profit and not so much about quality control. Cheers, Alan R.
  9. Hey Tim, A local source of one of the Exicon equivalents in TO-3 case. Z1456 2SJ56 ECF10P20 P Channel TO-3 Power MOSFET Exicon - Altronics $13.40 ea in 10+ quantities. Not likely to be fakes. I've had a trade account with them for decades and never had a fake product from them. Besides Altronics has a 12 month warranty and also a 14 day money back guarantee if the devices don't measure to specification or marketing claims. Unfortunately they no longer carry the N channel complimentary device. Cheers, Alan R.
  10. Try here - ECF10N20 Metal Lateral MOSFET | Profusion (profusionplc.com) Looks like they carry TO-3 versions of these devices. When you click BUY NOW you can order the quantities you need. The intro page kind of suggests minimum 500 pieces, but you can buy in quantities as low as 1 piece. Price of course varies. Cheers, Alan R.
  11. Very nice work Suzy and well documented too. Very tempted to build a pair of these. Cheers, Alan R.
  12. The Bottlehead Crack is a simple amplifier using point to point wiring. If you follow the instructions carefully you should have no problems. Just be mindful that you are working on a project that involves mains (240v) and high d.c. voltages inside the chassis. These are potentially lethal and I advise you exercise care when working on this kind of gear. Electrolytic capacitors in tube circuits can hold a lethal charge for some time even after the power has been switched off. Contrary to popular misconception good soldering is an art. By all means watch a few YouTube video
  13. You can strengthen those hollow plastic feet by filling them with epoxy. Cheers, Alan R.
  14. The question that needs to be asked is "Is it a bearing that requires lubrication in conventional sense that the manufacturer provides a lubrication point and a recommendation to use a lubricant as such?" Some bearings require lubrication but conventional coating lubricants just don't work. These bearings are made from a porous material and require the lubricant to be absorbed or infused into the bearing in a vacuum environment. Once the process is complete the bearing can be reinstalled provided it wasn't too far gone to begin with. With use the bearing is self-lubricating until
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