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tube fanatic

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  1. It all depends on who you ask.  Cathode bias works very effectively and allows for totally plug and play operation with no tweaking ever needed.  If the tube draws a little more current the bias increases to maintain the status quo.  If tube emission decreases a bit causing less current flow, the bias will decrease accordingly.  It is impossible to maintain rock solid operating parameters with any circuit arrangement as the tubes themselves change over time with use.  As for the cathode resistors generating heat, that should not be a problem in any properly designed amp, and the resistor value is chosen to set a particular operating point.

    My recommendation to prospective tube amp buyers is to go with something which suits your needs.  If you don’t want to ever be bothered with making adjustments, a cathode biased unit is definitely the way to go.



  2. 22 minutes ago, tube fanatic said:

    And this is why so many folks I know will not consider the vaccines.  

    To add to the discussion, read this piece by a lay person with concerns about the vaccines:




    Most importantly, read all of the links he includes and explain to me why the information presented should be dismissed without consideration as seems to be the case.




  3. 2 hours ago, CECAA850 said:

    Nothing to see here, move along...........................



    • Pfizer received the biggest fine in U.S. history as part of a $2.3 Billion plea deal with federal prosecutors for mis-promoting medicines (Bextra, Celebrex) and paying kickbacks to compliant doctors. Pfizer pleaded guilty to mis-branding the painkiller Bextra by promoting the drug for uses for which it was not approved.
    • In the 1990s, Pfizer was involved in defective heart valves that lead to the deaths of more than 100 people. Pfizer had deliberately misled regulators about the hazards. The company agreed to pay $10.75 Million to settle justice department charges for misleading regulators.
    • Pfizer paid more than $60 Million to settle a lawsuit over Rezulin, a diabetes medication that caused patients to die from acute liver failure.
    • In the UK, Pfizer has been fined nearly €90 Million for overcharging the NHS, the National Health Service. Pfizxer charged the taxpayer an additional €48 Million per year for what should have cost €2 million per year.
    • Pfizer agreed to pay $430 Million in 2004 to settle criminal charges that it had bribed doctors to prescribe its epilepsy drug Neurontin for indications for which it was not approved.
    • In 2011, a jury found Pfizer committed racketeering fraud in its marketing of the drug Neurontin. Pfizer agreed to pay $142.1 Million to settle the charges.
    • Pfizer disclosed that it had paid nearly nearly 4,500 doctors and other medical professionals some $20 Million for speaking on Pfizer’s behalf.
    • In 2012, the U.S. Securities and Exchange Commission announced that it had reached a $45 Million settlement with Pfizer to resolve charges that its subsidiaries had bribed overseas doctors and other healthcare professionals to increase foreign sales.
    • Pfizer was sued in a U.S. federal court for using Nigerian children as human guinea pigs, without the childrens’ parents’ consent. Pfizer paid $75 Million to settle in Nigerian court for using an experimental antibiotic, Trovan, on the children. The company paid an additional undisclosed amount in the U.S. to settle charges here. Pfizer had violated international law, including the Nuremberg Convention established after WWII, due to Nazi experiments on unwilling prisoners.
    • Amid widespread criticism of gouging poor countries for drugs, Pfizer pledged to give $50 million for an AIDS drug to South Africa. Later, however, Pfizer failed to honor that promise.

    And this is why so many folks I know will not consider the vaccines.  If paying huge damages is not a deterrent to turning out a dangerous product, why would they care when there is no liability?  As has been made clear, the manufacturers cannot be sued and people who have been harmed must go through the government CICP which rejects virtually every claim made.  Remember also that Pfizer refused to supply Brazil and Argentina unless they were given access to the sovereign assets of those countries from which they could draw to pay damages.



  4. 8 hours ago, WMcD said:

    After the second Pfizer I had a little ache while reaching for a bottle of ketchup.  That is all.


    "Doctors and scintists can't tell you the long term effect. "   Ridicule is not sufficient to address this.  The scientists didn't use the flux capacitor Delorian to go ten years to the future and check the results?  Gasp. They didn't even use the Sherman-Peabuddy Way-back to go to the past, jab a few people and then see the effect in the present.  Double gasp.


    People who harp on this lack of information as if they have seen through a magnificent deception do not have the sense that God gave a goose.  They are dangerously sophmoric (wise fool).


    Being vaxed is not a matter of whimsical or political personal choice -- that crabby refusal kills our fellow citizens. (Daddy, why did grandma have to die?  Was it because you refused to get a jab?) They should be forced to go to a nursing home or hospital or even India where people are attempting to breath their last breath, and can't.  In India the funeral pyres are in the hospital parking lots.  The anti-vaxers should go and help chop wood.



    Gil, I know fully vaccinated folks who when out walking cross to the opposite side of the street and pull up a mask when someone approaches within 50 feet of them.  Yet, they say that they feel protected by the vaccine!  Additionally, asymptomatic spread is not as concerning as once believed.  The PCR test used here is cycled so many times that totally inactive, non contagious, virus fragments result in a “positive” report.  Some very notable virologists and epidemiologists at US hospitals have said this many times.  

    What I ask folks who say that they believe they are protected by vaccines is why they are so afraid to get near anyone.  They should not be concerned in my opinion.




  5. 20 minutes ago, chn68b said:

    So now I'm back to square one. Some say yes, some no? 


    Is there an easy way to accurately measure the wattage I'm using at the volume I like? 


    Edit: no by the look of it. 

    Yes, there is:   https://community.klipsch.com/index.php?/topic/170414-who-wants-to-measure-how-much-power-voltage-is-really-needed/


    If that doesn’t work for you I can give you a simpler, but less accurate, method.



  6. This section was created to be a repository of info about using tube amps with Klipsch speakers.  When in 2 channel these discussions were quickly buried and were difficult to search out.  I think this section has fulfilled its mission quite well!


    As to the issue of power, it depends on so many factors that one needs to try an amp in their own system and draw their own conclusions.  Deckert offers a return policy for that reason.



  7. I was hoping that Al furnished the Forte plot with the crossovers.  You may want to ask him for it.  It is strange that you are hearing slight distortion at low volume levels.  Is your amp the Spudkit?  If so, ask Jerry if he has encountered this with other Forte users.  What other amps have you used with the Fortes successfully?



  8. 8 hours ago, brl0301 said:

    its super timely that this topic came up. I recently build a spud amp (6cl6 based) and it sounds great on my cornscalas running alk crossovers. I recently tried the same amp on my forte ii and it was a different story. I know that the forte ii are supposed to be a pretty rough impediance load and the alk crossovers are supposed to create a nice easy speaker to drive. 


    The amp is borderline unlistenable on the forte ii but 90% as good as anything ive ever heard on my cornscallas. Does this seem like the issue that Im running into?

    It may be.  Can you get the impedance plot for the speakers with the ALKs?  With the factory crossovers there is a huge impedance rise in the midrange which the resistors would bring way down.  

    In what respect are they unlistenable?  



  9. I asked some friends, who will never consider taking the “vaccine”, why and one sent this:




    Since the “vaccine” does not prevent a person from contracting, and potentially infecting, others they do not believe they have any moral obligation to take the risk.  I always like to consider points of view which are not mainstream, so their perspectives are interesting to me.



    • Like 1
  10. No one seems to be thinking about the impact on the environment of disposing of billions of masks every month.  This will be another pollution nightmare.  The states which have dropped the mask mandates have made a good choice in my opinion.  And if the “vaccines” are so effective, why are recipients still encouraged to wear them when indoors with other recipients?




  11. 35 minutes ago, steelgtr said:

    Is this little guy a true single end amp? EL84 is a pentode so it can't be a SET right?  (still learning)



    Any pentode can be wired to operate as a triode, and there are many wonderful SETs which use pentodes wired that way.  Some pentodes, when “triode strapped”, have more linear characteristics (less distortion) than some popular triodes.  Triode purists may disagree.......



    • Like 1
  12. I don’t understand why individuals who are rejecting the “vaccine” are being vilified.  Corruption and data falsification in the pharmaceutical industry is no secret (there is still lots on this to be found online), and the FDA is not totally innocent either.  The concerns of so called anti vaxxers are well taken and I don’t personally know any who apply their belief to anyone other than themselves or their families.  A friend, who won’t take the current “vaccine”, sent this link which highlights some of what I said:




    Personally, I never trust data generated by a pharmaceutical company, especially since the Vioxx scandal.  Add the total liability shield under which Moderna, Pfizer, et al are operating and being skeptical is justified.





    • Like 2
  13. Some additional information can be gleaned from this old thread on the forum:




    When one considers that the output impedance of some SEPs without feedback can hit 30 ohms or so, holding the speaker impedance to a narrower range is certainly valuable.  

    My work with SEP spud amps (no fb) has been enlightening in this area and all the future builds will include an internal, switchable, snubber resistor.  Such amps can really sound nice!

    The SET crowd snickers at us guys who still use pentodes...😄



    • Like 1
  14. This remedy addresses issues with pentode amplifier characteristics (high output impedance and high plate resistance) as opposed to deficiencies in crossover characteristics.  I don’t know many audiophiles who would be qualified to reconfigure a crossover which, of course, would change what the manufacturer had in mind.  Installing a resistor to make the amp “happier” is something anyone can do.



  15. Agree Mike!  But that is the nice aspect of using Klipsch speakers most of which are so efficient (as you know!) that the power loss is not generally an issue.


    The resistor does not turn the speaker crossover characteristics into a purely resistive situation but will lower the effective impedance seen by the amp.  The graph on the Zu link above demonstrates this.  Even if the speaker impedance drops to 4 ohms, the resulting slight decrease should not be a problem.  I usually use 27 ohms which covers most situations nicely.  It is the very large impedance increases which the resistor really helps to contain.



  16. It is no secret that tube amp/speaker synergy is very important.  This is especially true with single ended pentode amps which do not employ negative feedback and are sensitive to speaker impedance variations across the audio band.  A trick which I, and others, in the design world have always used is a resistor across the amp output terminals, or speaker terminals, to keep the impedance the amp “sees” more constant (i.e.“flattening the curve”, an expression with which all are now familiar).  It can make a huge difference and allow amp/speaker combinations which may not sound great to suddenly become glorious.  

    So, it is gratifying to see a speaker manufacturer actually promoting such a tool:




    The resistors they furnish can be purchased for a few dollars less but will not be matched.   As someone who designs single ended amps which are used almost exclusively with Klipsch speakers, I can tell you that using the resistors can be a worthwhile tool.



    • Like 1
  17. 4 minutes ago, Zen Traveler said:

    I am far from a lemming and am waiting for you or someone else to post something contrary to what the experts are saying. 


    Do a search and you will find many highly credentialed docs and scientists who disagree with the mainstream view.  Unfortunately, they have been branded as “quacks” and the self appointed social media arbiters have declared their work as being unfit for dissemination to the public.  You know as well as I that only certain viewpoints are being permitted.



    • Like 1
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