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Jeffrey D. Medwin

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About Jeffrey D. Medwin

  • Rank
    Forum Veteran
  • Birthday 11/27/1944

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  • Gender
  • Location
    50 miles East of Kansas City, MO.
  • Interests
    Audio, music, and the stock market, ..............is there anything else ?
  • My System
    Two stage Direct Coupled DIY triode amps, careful wiring, very lightly-modded professional - use speakers.
  • See My System

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  1. True. But. Mine hardly ever have failures, and any need to do a repair, due to a far superior implementation, starting with the chassis. Look more carefully at just the thickness of the chassis / metalwork in the two amp photo !! View how thick the steel chassis is in both is please. Mine is made out of rigid, vibration-minimized 12 gauge cold rolled steel, with welded corners. The lower amp has a thin, cheap chassis, looks like its made from recycled tin cans in thickness alone. Transformers and magnetics vibrate when operating, and it vibrates the tubes also. Mine is 14 years old, and has five amps built in it. Jeff Medwin
  2. AMP BUILD PROGRESS REPORT..............................................................12 - 03 - 2020 No pretty pictures here, but some very exciting news !! Yesterday, I discovered a fundamentally different B+ filtering topology, that has never been done before in audio, and it seems to have substantial effects on what we hear from an amplifier at our loudspeakers. I am thinking these thoughts...1) this could be patentable and / or 2) this could lead to either my Mentor Dennis, applying it to his Serious Stereo new amps, or 3) perhaps me personally going into the amplifier building business, small scale, for others. Right now, I have to work out several developmental details, in my 6005 SE DC prototype amp, so that the unit will be a representation, of what my new circuit innovation has to offer. If William Z. Johnson ( who I knew, along with his second wife, Nancy ) can call his Audio Research Corporation gear : " High Definition " I would tend to call this new circuit topology " Higher Resolution ", because it will be an edge in circuit design, that was never ever developed by anyone ever in audio, until yesterday, by me. One of the things I love about this, is it is all done 100% with passive parts, no solid state parts are employed. And its simple in design. It took, someone just like me, and it seems like only me, to design it !!! Remember me posting on this Forum " In the end, we all listen to a modulated power supply , how good is it ?" Well this addresses that most basic, and the most overlooked and misunderstood aspect of tube amplifier design. Where will this lead me, and importantly, how might others derive the benefit??? Jeff Medwin
  3. I'll show a top-side photo, at some point in time. Its an old old chassis being reused. Welcome to the Klipsch Forum.
  4. There are a wide variety of people who post on a public audio Forum. They have a wide variety of personal experience, with understanding amplifiers, and personally building them. It's the fifth amp built in that chassis over 14 years. Are you able to post some below-deck photos of SET amps you have personally designed and built? Maybe I am missing something in my execution, and you can assist me. Thanks, Jeff
  5. Two engineers are pleasure riding their bikes along the Santa Monica beach bike trail. One of the engineers glances over to the other and says, " I see you have a new bike . When did you get it? "Well", says the second engineer, "you'll never believe how I got it" Engineer #1, "Tell me." Engineer #2, " I was riding in the park last evening when this beautiful girl rides up to me, winks at me, motions for me to stop. We do. Then she smiles at me, gets off her bike, and starts removing her clothes until she is naked!!" Engineer #!, "Wow, what happened next?" Engineer #2, "She smiles at me and says, take what ever you want. I took the bike". Engineer #2, "Good choice. The clothes would never have fit you!"
  6. AMP BUILD PROGRESS REPORT ...................................... 12 - 01 - 2020 Got all six of the new Russian Caps GE Silicone 2 positioned in place and semi neatly wired , 14 AWG Mil Spec. These six green bypass caps are going to 6 of the 7 key capacitor areas of the amp. These six Russkies are added to augment the mid bass to lower midrange's music presentation. I find a single high quality film cap, on its own, can not do this as well. To every key capacitor position of my circuit, I also will add separate bypass caps to augment these following music ranges : mid bass, midrange, lower treble, and highest treble. When I listen to just one good film cap, in any spot in an amp or a speaker crossover, I get just " so much " music performance. Once you learn how to properly do multiple film cap bypassing, in a tube amplifier, you will never ever be satisfied to live .... without it !!! It is like holding hands with your date, and being fully satisfied, VS: doing much more. Notice above, I often slightly separate ( position ) one wire one from another, and try to cross differing wire fields at right angles. The Yellow ( 12 AWG ) and Blue ( 14 AWG ) Mil Spec wires are B+. Green is ground return, to a 12 AWG M22759/11 ground buss. Above, a single star point ground, a brass bolt, brass washers, and brass nut. It sure looked "messy" yesterday. Above, Power Supply : Dual 5U4GB rectifiers, their bronze endbell filament transformer ( 5VCT @ 6A.) nearby, feeding a sub ten Ohm L1/C1/L2 filter chokes in the photo. Voltage divider and black cap raise filament voltage to the directly coupled Final tubes, which are elevated about 160 + VDC, above ground ( the voltage on the plate of the 6DJ8 ). That hole in the chassis ( above ), between the ON-OFF switch, and the bronze filament transformer, is for a second ON-OFF switch. It will allow me, once the amp has started, to illegally short out the fuseblock, to get maximum dynamic contrasting, when I am in the room with the amp. I call it my very own " attended listening " switch. The joys of DIY. Now, to fire this up, and recheck all voltages before listening some. I will next execute a bottom cover ( 14 gauge steel ) which also acts as an isolation platform. That is to do on another day. ' Wanna hear this - now that all the basic multiple bypass caps are in place. All of this gets tested, after voltage checks with my Fluke 8060A, on familiar reference music material. No O-Scopes need apply. How does it sound on music, a well miked grand piano, sax, trumpet, cello, and a drum kit ???? Jeff Medwin.
  7. Tonight, I GE Silicone 2 glued-in-place ( "shoe - horned in" ) five of the six needed big green - colored Russian bypass caps, with long leads attached. In a day, it will be dry. I will neatly cut down and attach the flying leads, install the sixth Russian ( paper in oil ) cap, and try to finish the build. I am using 100% film caps in this build, as I always do, the last dozen years. Film caps, first of all, are long term reliable, and if properly chosen and carefully combined, they can usually sound nicer than shorter-lived electrolytic capacitors, commonly used in amps. On the B+ supply to the Driver's Plate resistors, I am using a multiple ( five ) film cap combination, to get the musical nuances and linear frequency spectrum I want, and can never satisfactorily-to-me get out of a single film cap. In fact, the cathode resistors of all four audio tubes ( two channels ) will each get that same ultra-careful five-film-cap treatment, as will the 50uF WIMA film cap, supplying the output transformers' primaries, which in effect, is the plate B+, for each 6005 Output tube. This amp fired-up fine, on Saturday, and I have been doing some power supply listening and designing ( to the Drivers) on Sunday. I came up with a unique-in-audio new B+ filtering innovation, for the front end B+. It is a brand new design topology, B+ filtering, that pretty much excites me - with what I heard. ( Appreciably better inner detailing / resolution and dynamic contrasting ). Please realize, this is the fifth amp built in this chassis, so I was constrained in my lay out, and how it looks below deck. I will know more, later in the week, when all seven " C " ( or capacitor ) locations, gets their full-complement of five film caps each, and they break-in some. This circuit is ultra simple, half of a 6DJ8 ( or a better Russian equivalent ) directly coupled to a 6005, operating ultra linear through the output transformer. Ohh, dual E.H. 5U4GB tube rectifiers, to do peak power and dynamic contrasting to my personal satisfaction. Lots of m22759/11 Mil Spec wiring was used, and a certain amount of silver wire in critical signal spans. What I am showing, is just a work in progress, in an highly used chassis, so don't expect perfection. The GE SILICONE 2 is drying / setting -up now ! 24 hours. This stereo amp uses more Caddock Resistors ( 9 ), than any that preceded it. Chokes are all under ten Ohms DCR. Jeff Medwin
  8. What do the Japanese know about tube audio, that we Americans don't ?? Nothing. That guy, who I have never even heard of, does not know the most rudimentary things, on how to lay out an amplifier properly. The Power Transformer and the rectifier tubes have to go as far away as possible, from the amp's sensitive input signal tubes. Putting a rectifier between two input tubes, is absolutely a novice's total stupidity showing...no thought , he likely didn't know better. It is the worst place possible to position a rectifier tube. Now YOU know this also. Welcome to the club. Jeff
  9. Work in progress....as of tonight, more to do . In a four-time-used chassis.
  10. Besides the zip ties, the Manufacturer positioned the rectifier tube, right between both input tubes. Think about it for a moment. The rectifier tube has the nastiest of fields associated with that function. Of course, everyone caught that - right away,...... except for the Manufacturer. Those neatly spaced tie wraps and red and white wiring will sell amps, if you are impressed with that. Those electrolytic caps are nice also. See that 6 Watt 18 Ohms power resistor between the rectifier tube, Pin 8, and the choke? Sure, go ahead and add some series resistance to the Finals stage, it doesn't matter at all. Its all very nice ! Glad to have seen it. Is it three grand, or four, or five or six? I'll take it out of my 401K. Red and white wires, wow, and blue to sell to us, in the USA. Will this piece get me that " tube sound " that everyone talks about in audio ??? Jeff
  11. I would simply slowly, maybe over several hours, variac the units to a full 120 VAC home line voltage and give them a listen. Do not be so anxious to modify the caps, as the amp was built a certain way. Any cap change will make the amp sound different, but not necessarily better. Plus, how competent are you, in wiring, soldering and parts layout, VS Ron's original attempt. You are a novice, he was a pro. Only after you have lived with the piece, for a while, many months, should you go in and systematically change parts. But any possible changes should be researched really well by you, prior to doing any changes !!! Jeff Medwin
  12. $500 for two monoblocks is very little, almost nothing. The price alone .....may be a red flag !! Don't know. I don't know where you and he live, but it could be $100-150 for each mono amp, for shipping, not including packing. The external heatsink in the photo is a packing problem, for sure . I personally would not trust the average packing shop, to pack them for you well. Depending upon how heavy the chassis is, and how he mounted all the components, there is a good chance that the units will be damaged in shipping. Then you will have to get them repaired. A DIYer builds the unit with the mind-frame that it won't fall apart in his living room, or recreation room. A Manufacturer designs and builds so the unit will withstand shipping drops. The seller is hesitant to ship, perhaps ......because he feels the unit, as built, won't safely get to you . I am just sharing some thoughts, you get to do what ever you want to do ! Jeff
  13. This is a different deal than what you led "me" to believe. I thought you were buying these directly from Kevin at K and K. There is no telling how well these are laid out, parts choices, and actually built from scratch, by the average DIYer. I would say there is far more risk involved, than I had originally envisioned. A DIYer's build will vary widely, from what Kevin himself may do. I would not be so inclined to buy these "blind " as I see more and more of whats going on in this thread. So, I would like to alter my first post, where I was encouraging you to act. What were you going to pay for these, prior to shipping may we all know? There may be other, safer alternatives to consider. Jeff Medwin
  14. Holey smokes !! I would suggest you buy them in a heartbeat. I have no affiliation with Kevin of K and K . I'll tell you this : He is one of the better designers in tube audio. He, like me, is getting older, and perhaps he is wanting to lighten up on units on his shelves !!!! You will likely get much much more than your money's worth, in both build quality and in performance / and in value. The GU50s are a fine output tube !! Kevin knows all about the Russian small signal tubes, and he runs them conservatively, so they will last !! MY mentor in audio runs one of his phono preamps, and it's a huge winner. I have tons of respect for Kevin, and his work, his knowledge, whereas , usually I dismiss most audio products as being mid fi designed, and poorly implemented. I just do not think that will be the case here. You should consider yourself lucky to have these monoblocks made available....from K and K. . It will be something to keep using until you pass them on to your grandchildren. Please let me know how this goes for you !!! BTW : Leave the circuit alone, and do not try for more power !! It is all you will ever need, those seven Watts on a Klipsch La Scala speaker. Jeff Medwin
  15. It looks like,on the inside photo, those are two circular moving coil type Input transformers on the bottom, so, without doing any additional checking, I'd guess it has a MC capability on phono. You might want to give it a listen, before booting it out the door. USA made no less. Jeff
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