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Everything posted by CindyJarvis

  1. I thought sound can't propagate in space? It is a vacuum after all right? -Cindy
  2. Once again please don't include me in your witch hunt. And personally myself and most competent engineers usually lift the center tap to around 50vdc and not 2-3v. And here I don't mind educating you because it appears you need it. Elevating the heaters will reduce hum by reducing or saturating the leakage current between heater and cathode. You know nothing about me so don't begin to think you do. The laymen on here might be impressed with your bullying but anyone with a pinch of technical prowess can figure out you don't know bull. You act like a scared animal backed into a corner when presented with a technical question. But hey I get it, if you can't answer the question by all means attack the credibility of me but all it does is prove you know nothing and that you would be better off being a politician than an "amp tech". Everyday I am here you prove yourself more and more incompetent in my eyes. You can do two things, continue with this charade or just speak your mind and prove me wrong. Oh and I do read your other posts and I find it a bit sad you have to drum up business the way you do, it's actually pitiful. Someone needs more hugs in life or something -Cindy
  3. The caps can be what ever dielectric you want, Aluminum are the cheapest. The 47uF must be 10v or higher and the 10uF must be 250v or higher. As for the 10uF cap, if you want to go with a higher quality film cap you can lower the value depending on what you think it will be driving. Basically if it is being plugged into an amp I don't think it will see anything lower than 100k, this means you could use .33uF. 10uF was kind of a safe value so you wouldn't get any bass rolloff while driving heavy loads. The 1Meg is a load resistance which will be in parallel with whatever you plug in. -Cindy
  4. I think I figured it out. I biased the follower so that it is really close to 0v so the two stages interact with one another. It should be rich in second order harmonic distortion. Gain is around 18db. You could always stick a volume pot at the input too but I assume your instrument has volume controls. What do you guys think? -Cindy
  5. I drew something up for the tube builders to take a look at, problem is I can't figure out how to upload it to the forum. Anyone care to help me? -Cindy
  6. I can draw something up if the tube guys haven't already. A couple more questions. Are your bass' pickups active or passive. Same question for the acoustic you plan on getting. -Cindy
  7. Yes. You should still be able to drive a reasonably long cable like 10'-20', pick a higher transconductance tube and get a lower output impedance, plenty of current too, 5mA-10mA. How much gain do you want? How about adjustable gain? Tone controls? The world is your oyster. -Cindy
  8. http://www.ampeg.com/pdf/svtdi.pdf Most guitar amps don't have a balanced input. Keyboard amps do I guess. The device is meant to drive a long cable from a stage to a soundboard. The block diagram does show what looks like a common cathode gain stage directly coupled to a cathode follower. The cathode follower will have a low output impedance and the output transformer lowers it even further and converts to balanced. Make note of the -14db gain. I find it strange because with all passive pickups there will be a resonant spike in the midrange, the placement is dependent upon the parallel capacitance of the cable and the inductance of the pickup. I think this is why most guitar amplifier tone stacks will scoop the mids to to flatten things out. Of course if you were sending the signal to a soundboard with a competent engineer he would adjust the sound accordingly. But most people that wouldn't know this or don't have the ability to flatten the mids might end up with a lumpy sound with boosted mids. Other than that I am sure someone here that builds amps could make you something very similar relatively easy. -Cindy
  9. Hello, do you have them all plugged into the same electrical outlet? If not try doing that. It sounds like a ground loop passing through the interconnects. The reason the iphone doesn't do it is because it is battery powered. -Cindy
  10. Any other people out there using chopsticks regularly? We use them in the house all the time, I think it's a fun way to eat. -Cindy
  11. Are amps 'A' and 'B' the same? If yes running different rectifiers could yield audible differences depending on the topology of said amplifiers. If the amps are not the same it's like comparing apples to oranges. Depending on the topology of the amp you could hear a difference. Power tubes in a common cathode configuration with the output taken from the plate takes a small change in voltage at it's grid and creates a change in current at the plate, this change in current across the plate load (Rp) creates a larger voltage swing. All tubes manufactured slightly differ, even in the same production facility, these small differences can be audible due to the amplification nature of the device. A rectifier has zero amplification of signal, it's only job is to pass current in one direction and that's it. It does this by physics, the electrons boiled off the cathode can only flow in one direction, to the positively charged plate. -Cindy
  12. Jim you bring up some good points to the "why's". Maybe if the countries ideals don't change for the better at least kids can start eating more healthy. -Cindy
  13. Yes, it appears we have reached our saturation point. Let it grow! -Cindy
  14. Yes I see what you mean, that is a more precise observation. The educational system wouldn't be the way it is if we hadn't made it that way. I guess the real question is will it ever be reversed? -Cindy
  15. Well if you are concerned with the audible difference the biggest will be caused by the internal plate resistance (rp). In a class AB amp there can be large current differences between quiescent state and full signal state, this change in current causes a change in voltage across the rp and the result is audible in the form of compression, or "sag". The less this resistance the stiffer the supply is. Changing a rectifier out with more or less rp will give you more or less sag. In a class A amp like the Yamamoto A08-S the current draw is relatively the same from quiescent state to full signal state so there is little change in voltage across the rp. BUT when you change from one type rectifier to another with more or less rp you will get more or less quiescent voltage, this can result in more or less power available since a lower plate voltage means less of a voltage swing. There are a lot of other things to consider from an engineering standpoint when choosing a rectifier but I won't get into that unless anyone really wants. -Cindy
  16. I use the directly heated 5U4GB. My other tube amp uses silicon, UF4007 in a bridge. -Cindy
  17. I just love Japanese kids they are so cute! I think it's great how the kids thank the adults so much for the lovely food. I know of one private school that serve very fresh and healthy food, the administrator told me it's not even any more expensive than the government garbage the public schools serve. I also like how they have to clean up after and brush their teeth. The fact they ask the kids of any illness before handling the food is very important. It's a 180 degree difference from our school systems. I am certain they learn a lot more there too. The Japanese are taught respect, something I see very little here in the states these days. This video should be an eye opener for us but it most likely won't be. Our educational systems have failed us. Thank you for sharing! -Cindy
  18. Post 7 Post 8 Post 12 You mean the heaters being only AC grounded that you mentioned in post 7? This is too easy, I thought you were a big shot tube amp guy the way you carry yourself, but honestly you aren't proving to me you know as much as you think you do. I also don't think this obsession with this other person "xxjpmxx" is very healthy. What did this guy do to you? From my reading it looks like he ticked off a few other members but I can't seem to find anything where you two go at it. Can anyone shed some light on this for me and give me some links to the good stuff I seem to be missing. -Cindy
  19. It's a more likely scenario in that you actually don't posess the ability to answer any of my question. I didn't think you were an engineer an engineer, more like a kit assembler. It's nothing to be ashamed of. I think I may be the one educating you -Cindy
  20. NOSValves, stop harassing me. I don't care who you think I am or what you think I sold. With you trying to get back at the person you think I am you in reality are actually only making yourself look worse. Especially technically. Now if you want to have a real conversation about electronics then grow up and lets talk, or better post a schematic of what you are talking about. My understanding is you think in an indirectly heated tube the heaters need no DC reference? Heaters should not float; they should always have a DC reference (the simplest is just ground). Some people don't understand this and think that a capacitor to ground is sufficient. If they don't know what voltage their heaters are floating at, how can they know that they are within the heater-cathode voltage spec? Although they don't realise it, they are relying on leakage currents or insulation breakdown to set the heater potential. An example of this is in the Dynaco ST70 amp so if you have copied this bad habit form them then it's your problem. If you know something that I don't please enlighten me. Heater Circuit is on the last page. http://www.thehistoryofrecording.com/Manuals/DynaCo/Dynakit_ST70.pdf -Cindy
  21. So what you are telling me is that those amplifiers were in service probably working great for 30+ years and then you "PROFESSIONALLY" rebuilt them and now they need to be serviced every few years? That doesn't sound right at all. What about your "VRD" amplifiers? Why use modern production tubes that only last a couple years in their designs? -Cindy
  22. Troll? If anything I helped prove the amplifier in question meets required slewrate and it also has very good bandwidth? Not too sure what you consider trolling? Maybe you misunderstood my posts? -Cindy
  23. Thank you oscarear for bringing up a great point!! There are a number of threads/posts that are about politics which from my understanding are against the Terms of Use. A couple times I wanted to join the discussion but felt it best to stay out of it. Like I said the rules seem confusing to me because they aren't enforced all the time. -Cindy
  24. Yes I got a warning point issued to me. I just feel like I was sticking up for myself from his attacks. https://community.klipsch.com/index.php?/topic/162090-my-bespoke-st70-amp-build/page-2 Post #38 -Cindy
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