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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
    Currently using RF-15s in a small room, near-field, arrangement and driven by low power SETs. The soundstage is enormous, and the musical involvement beyond anything previously experienced.
  1. inherited some stuff.. please enlighten me

    It is possible to use push-pull opts single ended. I would need to see a schematic of what your father in law did to determine if his method was valid. If you have the time to reconstruct his modifications and post the schematic on here, I can look it over. Maynard
  2. Understanding THD in tube amplifiers

    The reality is that it is impossible to correlate a single parameter with a particular sound. There is simply too much going on. Rod Elliott, with whom I agree about 99% of the time, did a nice overview of this issue: http://sound.whsites.net/amp-sound.htm No question that Ski Bum's statement is true based on my years of experience. Push-pull is a necessity when high power is desired from tubes at reasonable cost, but overall it has many disadvantages. The only way push-pull can deliver on its lower distortion promise is to maintain perfect balance in the phase splitter and output stage. Unfortunately, tubes never age identically so the balance is always in a state of flux. And further, there's the issue of so-called matched tubes. Regrettably, most vendors match at a single operating point which is vastly different from the actual operating conditions. A curve tracer, which few have, is the only way to match tubes to perform similarly across their entire power curve. Single ended, using cathode bias, is truly the best way to go as it is a "plug and play" arrangement which self adjusts as the tubes age (in my opinion it also sounds vastly superior to push-pull amps as well). Maynard
  3. Audio Myths and Human Perception - Explored

    I'm surprised that this discussion hasn't included Cardas' work on speaker placement (unless someone posted the following link and I didn't notice it): http://www.cardas.com/room_setup_rectangular_room.php Mike mentioned "envelopment" in some post above. All I can say is that by using the proposed speaker placement the envelopment, regardless of listening level (I have tried this at listening position levels of around 60 to 85 db in multiple sytems), is totally extraordinary. And, the best part is that it doesn't require any fussing or bothering with acoustical treatments or equalization. I invite anyone who is blessed with having a dedicated listening room to try this. Maynard
  4. The appeal of tubes

    Myths are popular when it comes to tube equipment. Firstly, many SS amps run hotter than many tube amps. Secondly, many tube amps don't require a user to incur any more expense than SS amps- depending on the design, output tubes can last 25k+ hours. That's 25+ years at 1k hours/year of use. Purchasing a couple of spare sets of tubes for $50 or less isn't much of an expense in the context of other audio expenditures. And lastly, tube rolling is a sub-hobby which is absolutely not needed. Guys who are into tube rolling often do so for the pursuit of audio minutiae. As with rca cables, speaker wires, and so on it can be analogous to a dog chasing its own tail. Maynard
  5. Audio equipment repair west coast

    I first heard of this guy last night. Looking at his extensive photo library, his work looks really good: http://www.raincityaudio.us/projects Maynard
  6. The appeal of tubes

    I find it interesting that some of the most popular SS amps are revered for their "tube like" sound. As I've said many times before, we're fortunate to have so many high efficiency Klipsch speakers to choose from as almost all have excellent synergy with virtually any tube amp. It all comes down to the amount of power needed to satisfy a given listening level. Those who have taken the required measurements are often amazed when they find out that even 1 wpc is more than enough for any level at which they listen. Maynard
  7. Fall/Winter EL84 Monoblock Project-Some Questions

    I thought I heard a voice in the far distance calling. The sound must have taken longer than expected to arrive here! That amp is one of many inverterless push-pull types with differential output stage which were popular back in the day. Although the balance between the output tubes is far from ideal, these amps can sound amazingly nice. R6 is the shared cathode resistor and must not be bypassed or the amp won't work. As to the p/s, do not increase C3 to a higher value than 22 uf. However, since you are using a choke, you can increase C4 to even 220 uf with no concerns. That will really get the ripple down. As to the type of choke, unfortunately, the dcr wasn't specified and the true output voltage of the power xfmr is unknown. That said, a Hammond 156L should be fine. The p/s output voltage isn't going to be overly critical. Definitely use star grounding and a 3 wire power cord. You could move the volume control to the 6C4 grid and simply replace R5 with a 470k resistor. There are other possible modifications to that circuit, but we can deal with that later if you are not satisfied with the performance. As to metal film vs. carbon film resistors, I'm not convinced that it really matters except that the former will have much tighter tolerances. C1/R3 form a high frequency rolloff filter (similar to my famous "ear bleed" filter) which can certainly be useful in shaping the response to your taste. I'm not on the computer much right now, but don't hesitate to ask any other questions that arise. Maynard
  8. Top Ten Vintage Speakers on Ebay (inc RB-51 II)

    The Rectilinear III should be on any top ten list. There's a pair on Ebay right now. It's no surprise that they sound so amazing given some of the engineers who were involved with the company at one time or another. I sold a lot of them back in the day and deeply regret selling mine to one of the local guys about 30 years ago. https://en.wikipedia.org/wiki/Rectilinear_Research_Corporation Maynard
  9. Quicksilver Audio Tube Amps

    You probably need far less power than you may imagine and should be able to spend far less than your budgeted amount to achieve truly excellent sound. Since you are in California, I recommend getting hold of Justin Weber: http://ampsandsound.com/ But, if you decide to go with something in the Dynaclone area, Bob Latino offers excellent value in my opinion: http://www.tubes4hifi.com/ And, there's also Decware which offers many options which should work very well with K-horns (you certainly can't beat their lifetime warranty!): http://www.decware.com/newsite/homepage.html All of the above can set you up with amps which can be directly driven by a high level source like a CD player or DAC. That way, you don't need to spend any of your budget on a preamp. Maynard
  10. Audio Myths and Human Perception - Explored

    I don't have the time to write a long piece on my thoughts about this subject, but this will give you some idea about what could be going on (keep in mind that I usually agree with Rod Elliott on just about every subject): http://www.audioholics.com/audio-amplifier/the-sound-of-an-amplifier Maynard
  11. Audio Myths and Human Perception - Explored

    Mike, you and I have had enough discussions on here for you to know that I don't consider my words or opinions to be the gospel and that my mind is far from closed to the ideas of others. What I find offensive is someone who is considered knowledgeable making a statement which is too ludicrous to be allowed to stand. Such a generalized statement is a disservice to every person who is involved in the design of audio electronics. I'm sure that someone like Nelson Pass, among dozens of others, could write a long dissertation refuting the claim that they are "amateurs" simply because they know that electronic components can affect the sound of an audio system. Obviously, room/speaker interaction has a profound effect on the resultant sound. And, you have no doubt read many of my recommendations to folks on here in which I have asked them to try a small adjustment in speaker or listening position (among other things) as a means of changing an undesirable characteristic. However, I am also a realist in knowing that few have the luxury of a dedicated listening room in which they can hang panels, or use other physical devices to create the desired result. Most often listening rooms are shared with family members with the result being that certain compromises must be accepted. And it is in those instances that changing the electronics can often create a result which is far closer to what is desired. One last thought to leave you with is that if an active crossover is used to correct room and driver anomalies, isn't that using "electronics" to create a desired result? Along with that, many use different types of amps for each driver (such as SS for the woofer, and SET for the mid/tweeter). Again, one is using "electronics" to create a particular sound. If that is so, then Chris is as much of an "amateur" as I am. No, it is not. I invite you to visit a dealer and ask for some level matched comparisons of various SS amps. You will quickly be able to draw your own conclusion. Maynard
  12. Audio Myths and Human Perception - Explored

    So, as an expert in room acoustics, do you place any value on the role of electronics in producing the desired musical experience? And, if you do, please elaborate on the parameters of the electronics which have the greatest influence on the sound and explain why solid state equipment, in spite of minuscule distortion and near identical specs, can sound so radically different in a particular system. I would like to be enlightened since I am only a vocal "amateur"! Maynard
  13. Audio Myths and Human Perception - Explored

    Really Chris, you can't possibly believe this! Regardless of the perfection in speakers, room acoustics, and the relationship between the two, if you feed those speakers with an amp lacking the needed synergy the result will be poor sound. A true expert will consider every aspect of the reproduction chain starting with the source. One of the local guys, an acoustics engineer, designs recording studios and looks at absolutely everything before coming up with his design. To me, that's the only way to achieve the presumed perfection that some strive for. I question how many on the forum are willing to go the speaker/room acoustics route given the near total lack of response to even taking a measurement to find out how much power is needed to satisfy a given listening level. Maynard
  14. Audio Mirror equipment

    I'm not surprised at your impressions of the AM amps. I would expect them to destroy the popular p-p ultralinear amps any day. Did you sell yours because of the high heat generated? In a cold climate they could probably replace a space heater in a poorly insulated room! Maynard
  15. Audio Mirror equipment

    Wondering if any of you guys in the Houston area know Vlad or have seen/heard his equipment. It appears to be very well made and I've read some glowing reports of how his stuff performs: http://www.audiomirror.com/index.html Maynard