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  1. Replies
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    Thanks for pointing that out pdf64, I didn't...

    Thanks for pointing that out pdf64, I didn't think of it... Until I saw one tube red-plating ever so slightly, so I upped the shared power tube cathode resistor from 220 to 370ohms, and all is well...
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    Ok, just to make myself feel better, I added...

    Ok, just to make myself feel better, I added .047uf caps before tone controls. Hey, I just needed something to solder, and I realize there was little worry at this point.

    I got another plesent...
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    DC at both tone controls ?

    Just noticed there are no caps between the plate on the 6J5 and the first stage of the 12AX7, so DC appears at both the Treble and Bass controls. Is this normal on some amps ?

    I always thought you...
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    I used to support the notion that meters are all...

    I used to support the notion that meters are all the same... Wow was I ever wrong !!! I went through 4 or 5 cheap discount store meters in the span of two years, and that's how long it's taken me...
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    Looks like a bowl of noodles ! But hey, it's the...

    Looks like a bowl of noodles ! But hey, it's the opposite with amps from people for me, it's what it sounds like on the outside that counts... Provided it doesn't cause a fire, or go into...
  6. I've noticed this too, that some open backs...

    I've noticed this too, that some open backs generate more lows below the resonant frequency of the speaker, even though there is a sizable potential for cancellation of front to back sound waves, but...
  7. Interesting comment on the power supply caps...

    Interesting comment on the power supply caps Helmholz, I just checked those early today in the only way I know how, that is to parallel a good big 450v cap of at least the same value, and see if the...
  8. 470uf 50v cap. I must admit that I was driving...

    470uf 50v cap. I must admit that I was driving the amp input with a Seymour Duncan "Flat" boost (25db gain) and a with about another 6db of gain from a stomp box EQ, and at the front of all of that,...
  9. I think you may have hit upon it Chuck, and here...

    I think you may have hit upon it Chuck, and here is why. Yes I added a cathode bypass cap to the shared cathode resistor of the power tubes where there was none, and I also noticed that when I leaned...
  10. Overdoing a Good Thing !

    Recently I've been trying to extract as much lower Bass as I could from the power section of my smaller amps, figuring if some bass is good, then more would be better !

    Well I think I caught...
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    Thanks Helmholtz ! I missed the second Global...

    Thanks Helmholtz !

    I missed the second Global feedback loop. I will try the changes you recommended and let you know how it goes. I think I am going to leave the input filtration portion intact...
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    Made some changes to the amp to increase gain and...

    Made some changes to the amp to increase gain and change the distortion / tone.

    First thing I did was to knock back C9 (see negative feedback circuit) from .047uf down to .005uf, while...
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    Probably the single triode, I would guess as...

    Probably the single triode, I would guess as well. This "amp" is going to be a lot of fun for me, as it is close to a guitar amp by design, but I just received it as a chassis, so I can dig in at...
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    Been busy with family stuff, sorry for the delay....

    Been busy with family stuff, sorry for the delay.

    Here's the schematic on page 182 :

    http://www.nucow.com/SkizsPdfOnly/Supreme_1926-1969_Volumes/1957.pdf

    It's an old Zenith Hi-Fi amp, but...
  15. https://www.szynalski.com/tone-generator/

    https://www.szynalski.com/tone-generator/
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    Just found the schematic (It's seems very close...

    Just found the schematic (It's seems very close at first glance) online. I will take your advice and first measure everything over the weekend, to see if it's in spec or not. As usual for me, my...
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    That's correct Chuck H. Sorry, I didn't describe...

    That's correct Chuck H. Sorry, I didn't describe it well enough, yes I will rewire the socket to accommodate the 'New' and different 6SQ7 pin outs. Just wondering if I am overlooking anything else...
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    Swap out different Preamp Tube Type ?

    Is going from one preamp tube to another just a matter of making sure the tube socket pins are connected to the correct wires, as in #3 = plate, #2 & #7 = heater, etc... Is that all that needs to be...
  19. My guess is the speaker, as you already guessed !...

    My guess is the speaker, as you already guessed ! there has to be some changes in absorptive materials based on high humidity, I would think. Add weight to a cone and you will change the tone !
    ...
  20. I think Enzo makes a very good point. I woke up...

    I think Enzo makes a very good point. I woke up to this just last year, when we included another Led Zeppelin song into our repertoire ( What is and what should never be off the second album), and I...
  21. Quality is down in many areas, and it won't get...

    Quality is down in many areas, and it won't get better I fear.

    I remember several years back buying new aluminum rims from my classic car. The center cap screws they sent with the rims were the...
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    You Are 100% Correct. Seeing how I'm not a kid...

    You Are 100% Correct.

    Seeing how I'm not a kid anymore, when I got back into playing and buying equipment, I spotted those cheap MG speakers from a mile away. I've seen a lot 100watt Marshalls...
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    I don't think you can tell precisely just by...

    I don't think you can tell precisely just by looking at it as others have mentioned, but you could make a fair guess based on the visual size of the magnet and voice coil, as Chuck H indicated. I...
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    Might I suggest using this ? The ST-2 With an EQ...

    Might I suggest using this ? The ST-2 With an EQ in front of it is my "Amp Model" of choice, and it's amazingly inexpensive, and up to around 12 O'clock sounds a lot like a vintage Marshall Plexi....
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    Thanks for all the help so far. My laziness has...

    Thanks for all the help so far. My laziness has passed, and I will remove the old transformer connections when I test the new one, and now I know a bit more about the role of inductance being lowered...
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    Thanks Helmholtz, I have to read up on...

    Thanks Helmholtz, I have to read up on transformers a bit more and understand inductance. Now in the paralleling of the two transformers, only one will actually be connected to the speakers at the...
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    Test New Output Transformer

    Just got a spare 20 watt output transformer today that I think might help an amp of mine (A Gretsch 6162) to sound a bit better (more low end). The amp is running two 6973 tubes at 392vdc plate and...
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    I love to modify and "Hotrod" my amps to suit my...

    I love to modify and "Hotrod" my amps to suit my tastes, but I also spend a fair amount of time up front with a new amp using a parametric or graphic EQ at the very end of my rig chain - (just before...
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