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  1. These types of switches are a bit noisy (as in...

    These types of switches are a bit noisy (as in pops) and weird when they get old. I have two of them, and both "leak" some signal across even in the standby mode.

    I've become super good at...
  2. Thanks Helmholtz, I recognized that as a problem...

    Thanks Helmholtz, I recognized that as a problem early on, and tried to install a 470k input resistor to ground early on, but picked up a ton of hum, and this amp is super quite in it's stock form. I...
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    I also have three of those amps, the older...

    I also have three of those amps, the older version with no tone control, the ancient early 1940's version, and one other with a tone control from 1955, but that last one it uses a 6SQ7 tube and...
  4. Please Help me to Understand this Phase Inverter.

    Sorry, this may be a repeat question, but I will try to be more specific in my questions this time around, as I am still lost.

    54357


    What is the function of the .005uf cap just after the...
  5. Thanks ! Good idea, I've seen those tubes and...

    Thanks ! Good idea, I've seen those tubes and wondered. I will buy a couple and find out. This could be really good, as the amp already has a slightly bigger 20 watt output transformer and I've...
  6. Junk is Junk. I've only been at electronics...

    Junk is Junk.

    I've only been at electronics for a couple of years, but I have a lot of experience using cheap parts for auto rebuilds, and you get what you pay for (cheap part and cheap tools =...
  7. Yes, I think that's my problem, assuming...

    Yes, I think that's my problem, assuming automatic red plating past 12w or so.

    But still I've seen this now in the coin-based tubes, they all handle high watts. All my other RCA, Sylvania, etc......
  8. Ok. You are correct, I need to measure the...

    Ok. You are correct, I need to measure the cathode voltage drop !

    I think that's what Helmholz was saying in the first place, and I didn't get it and thought it was the same as the OT drop, it's...
  9. Here's the schematic :...

    Here's the schematic : http://schems.com/bmampscom/valco/National_1224_Tremotone.jpg

    I measured the hot tube voltage drop as 9.98vdc and the plate voltage right around 350vdc (fluctuating a bit)...
  10. Thanks Helmholtz. I realize that was a mistake. ...

    Thanks Helmholtz. I realize that was a mistake.

    But shouldn't the net calculated dissipation should be fairly close anyway since the cathode voltage is very low (plate voltage around 350vdc) ?
  11. 6V6 (other than JJ) that can take high plate dissipations

    I recently got an amp with two coin based G&E 6V6s and I love the sound of this amp. The amp with its stock 200 ohm cathode resistor (measured 219ohms) had a very high plate dissipation ( 15.5 watts...
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    I ran a test of switching from a pentode to a...

    I ran a test of switching from a pentode to a triode power tube mode on one of my single ended Valco amps, and reached a similar conclusion regarding the extra ripple and hum it created.

    The guys...
  13. Very Hot Amp Sounds and 'Feels' Better ?

    I realize this is entirely subjective evaluation, but here it goes.

    I've had occasion to run several tube amps over the years under extremely hot and poor operation conditions, as in out in the...
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    After my third or so not all that expensive...

    After my third or so not all that expensive repair to my beloved vintage amps, I got the message loud and clear, just like with my vintage cars. That Everything is old, so either you plan on paying...
  15. It's hard to make a fair qualitative analysis of...

    It's hard to make a fair qualitative analysis of someone else's likes or dislikes, and Nosaj stated, but I will just add a portion of my opinion to the mix. I much prefer tube amp distortion through...
  16. I would like to have the original speakers...

    I would like to have the original speakers re-coned very much, and would pay a premium to have that done, but it doesn't look like anyone has those cones, or the facility to fix the voice coils. The...
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    You guessed well, that's what it was, a ground...

    You guessed well, that's what it was, a ground from the speaker frame to the chassis. I've never seen that arrangement before on a Valco amp, but in my foggiest of memories from when I was a wee lad,...
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    Ok, LOL, I tend to have a quick trigger when...

    Ok, LOL, I tend to have a quick trigger when talking about modeling, that has been established on other boards.

    I used to own and gig with an early 70's Marshall Plexi, and about a Dozen or more...
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    I agree. Comparing a Digital Delay to a tube or...

    I agree. Comparing a Digital Delay to a tube or solid state modeling amp is like comparing your Lawnmower to you car. Both run gas engines, but are quite different in their function. You wouldn't...
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    Here's a link to the actual MOV (Varistor) so you...

    Here's a link to the actual MOV (Varistor) so you can purchase through Mouser if you are so inclined.
    ...
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    How about eliminating the diodes and using...

    How about eliminating the diodes and using Varistors between the CT and each leg of the push pull to protect the output transformer ?

    It's my understanding that this is "dormant" until you reach...
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    LOL, yes I will be short, as I don't want to be...

    LOL, yes I will be short, as I don't want to be shot ! I have to start proof reading I think.

    I drank a little last night, but I am reasonably sober now, one would think anyway.:)
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    Excellent comments so far, so I will be 'short' -...

    Excellent comments so far, so I will be 'short' - (correction : not shot, thanks g1) and try not to repeat anyone.

    There's also an advantage a tube amp has in handling picked or strummed...
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    I use a real tube amplifier and I also use some...

    I use a real tube amplifier and I also use some digital gear at the same time, and here's what I've done :

    Carry along a smallish super light JBL self powered PA cabinet along with my tube amp.
    ...
  25. Today I removed the 350ohm cathode resistor and...

    Today I removed the 350ohm cathode resistor and put in a 250ohm one in it's place. The original 200ohm factory resistor was actually 219ohms, so I decided upon the 250ohm as a good compromise to just...
  26. LOL, I should have read your excellent suggestion...

    LOL, I should have read your excellent suggestion before I took apart the amp today ! I found a suitable 350ohm cathode resistor in all my junk and put it in, but it's quite easy to take out again....
  27. Just got a strange thought... The amp is a combo...

    Just got a strange thought... The amp is a combo and this is not an ideal situation when it comes to cooling, as heat rises and can actual get caught in the pocket at the top of the amp, and get...
  28. It is biased pretty hot currently. The stock...

    It is biased pretty hot currently.

    The stock Supro (Valco) cathode resistor is 200 ohms, and I am sure that was ok for 115vac back in the 40's, but my outlet today is 125vac and sometimes a bit...
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