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tube fanatic

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About tube fanatic

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    tube amp designer

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  • Interests
    extracting the best possible sound from single ended tube amps using modestly priced designs and tubes.
  • My System
    Now specializing in extreme near-field desk top systems using flea power SEPs and SETs. This mode of listening must be experienced as it can be totally enveloping.

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  1. This has brought back memories of the power supplies my ham operator EE neighbor and I constructed in the mid 60s to power his 5 kilowatt linear amplifier for use on 40 and 75 meters. Of course, that amount of power was totally illegal! The station was built around a surplus Collins ART-13 which was an absolute "battleship." Lots of fond memories of his station. Maynard
  2. You are more insane than me (that’s a compliment)!!! Maynard
  3. Be careful about using blanket recommendations to influence your selection of brands. Many vendors will describe a particular brand as having all kinds of characteristics. While that may apply in some equipment, it certainly is not universal. The same applies when someone says that brand "A" sounds fantastic (to them- you may not agree at all) in their Lafayette amp and recommends it for use in any piece of equipment. Tubes act synergistically in a given piece of equipment. It may be the total effect which you are hearing, and not the influence of just the one tube. If you get into NOS tubes, be skeptical of those who tell you that the shape of a getter, color of the heat dissipation coating on the plate (typically gray or black), or color of the glass makes a huge difference in the sound. And with any tube, normal production tolerances which affect the spacing of the elements within the tube can affect the sound in some circuits. Usually the difference is slight, but may be discernible if one listens hard enough. These are general rules to consider. In the end, you need to experiment and trust your ears. That's the only way to know what makes you happy. Maynard
  4. Those tubes are totally different. I don't recall seeing the “C” version with EL84s in the output stage. Are you sure you don’t have an earlier model? Maynard
  5. I was old enough but was too busy working to go. So, I attended vicariously through my cousin who was living at a nudist colony near there at the time. Must have been fun! Maynard
  6. Very thorough review: https://hifihaven.org/index.php?threads/leben-cs300f-integrated-amp-with-matching-leben-rs30eq-phono-stage.5194/ Maynard
  7. Jeff, as shown below, you are missing out on a truly amazing listening experience! It's how I listen frequently!!! 😀 Maynard
  8. Jeff, now that the amp is back home, can you please post a 3kHz to 5 kHz square wave at around 250 millivolts across an 8 ohm resistor? While I agree that subjective impressions are always extremely important, I find it valuable to try to correlate what we hear with objective measurements. Doing that allows for other amps to be developed which offer similar characteristics. Also, if you have time, can you measure the output impedance as well? That too may shed some light on why the synergy between the amp and your/Dennis' speakers is so pleasing to you. Thanks--- Maynard
  9. He made the 10,000th post in this section. Glad things have been so successful here. Maynard
  10. Any fb loop which runs from the opt secondary back to the driver (even with only 2 stages in my experience) can be prone to some phase distortion issues. However, applying small amounts of fb locally at each stage pretty much eliminates that problem. I find with SEPs that some fb is needed and, if carefully applied, can result in an almost SET like midrange/top end and tighter/more potent bass which is useful for speakers like LSs and Heresys. That said, if a SEP is used at a small percentage of its total output power (say less then 25%), the distortion is usually quite low and the resultant sound very nice without using fb. We get into some definite personal taste issues here. In regard to the Hypex and Benchmark amps, I seem to recall that both use some nfb. Does anyone have definite info about that? Getting back to Cheever's thesis, I mentioned being fascinated by his discussion of the response of our auditory systems to harmonics and have started doing some research. So far, this article has been the most informative (it's a bit heavy in neuroanatomy but lots of info can be gleaned even if you don't have a strong background): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865599/ All of this raises some important points in regard to why some of us prefer certain types of sound from our audio systems. Apparently, there can be some wide variations in our neural wiring. Perhaps this is why some like the harmonic signatures of SETs vs SS vs PP and so on. And, in my mind, it can certainly account for why one person can be enthralled by one type of sound while another is driven out of the room. I'll have to continue reading about this as I go along. Maynard
  11. Jeffrey, I did not make any statement about the sound of your or Dennis' amp. As you astutely observed, I have not heard either. I simply questioned your statement that an amp which sounds good measures good. So, I must ask you what constitutes good measurements? I am a bit confused here as I had the impression that you and Dennis (since you have included him in this discussion) design totally by ear and eschew measurements since they will not influence any design changes. I look forward to your clarification when you have a free moment. Maynard
  12. I don't agree with this. There are many amps out there which measure poorly but sound wonderful to particular individuals. I always come back to the example of the original Darling SET which has around 15% 2nd harmonic distortion at full output (if I recall correctly)- there are guys who will not listen to any other amp after hearing one. And, Jeff, didn't you agree that the ripple of your LSES filter is fairly high and can result in some audible hum (please correct me if I'm mistaken)? Wouldn't the former be an example of poor measurement? As to using neg. fb, I'm one of those who does not consider it to be problematic at all. After all, it does extend bandwidth and lower output impedance. Personally, I don't like or use a global loop. Yet, when one looks at all of the renowned vintage amps which use the latter and sound outstanding it's difficult to reject the methodology out of hand. What I found most interesting about the guy's thesis is the discussion of the response of our own auditory systems to harmonic distortion and our built in cancellation effects. That's a subject which I'll have to research more when time permits. It's something which I haven't thought about previously. I understand Cheever's point about the amp being the determining factor in what we hear. As the last element before the speakers, its influence will be significant based on its output impedance and how it interacts with the speakers' impedance variations. I've always felt that preamps don't do all that much to alter the sound of a system. Maynard
  13. A friend saw this on AA and sent it over. This treatment raises some thoughtful points about why amps which measure extremely poorly often sound phenomenal, and why some amps which measure well can sound like crap: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.497.2126&rep=rep1&type=pdf It is well worth reading. Maynard
  14. I’m surprised that no one has brought up glyphosate, dicamba, paraquat, 2, 4- D, forced vaccination, water fluoridation, acetone/ benzene and other toxic chemicals in dryer sheets, and other chemical horrors which have been banned in many other countries. It seems that the more this stuff is banned elsewhere the more EPA raises the “safe” limits here. Maynard
  15. My wife, who has become quite a techie over the years, has been thoroughly enjoying this thread! She is amazed that Jeff is going to spend more on his 4 Dynamicaps at $66 each than the entire parts cost of one of my budget designs! She also couldn’t imagine spending $50 for a single tube socket which she doesn’t believe could work any better than the NOS Cinch sockets that I normally use. And, I can’t repeat what she said about cable tie colors affecting the sound...... This is what makes the hobby so much fun. Maynard
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