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  1. Replies
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    206

    Please post the exact schematic you are referring...

    Please post the exact schematic you are referring to, or a link to it.
  2. Replies
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    856

    With only 190V B+, a 5K primary will get you...

    With only 190V B+, a 5K primary will get you about 2 Watt. You should get one of those "Universal" OTs so you can adjust the primary impedance down to something below 2K where maybe you can coax 5W...
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    727

    It''s worth mentioning that the chokes are...

    It''s worth mentioning that the chokes are different. The Sunn chokes are 1.5 Henry, DC resistance about 50 Ohms. Current rating is something like 300mA. The Screen only chokes are usually between 5...
  4. The "Cam Switch" drums were usually specific to...

    The "Cam Switch" drums were usually specific to each instrument they were used in. They had a special machine in the Engineering department to make them as needed. The contacts on the PCB are gold...
  5. My favorite is the guy who asks "what's it for ?".

    My favorite is the guy who asks "what's it for ?".
  6. The original Fender parts were made by Amphenol....

    The original Fender parts were made by Amphenol. I have an old 2005 Allied catalog that lists the 3 wire equivalent as made by WPI under the part number 160-2N. If you google WPI 160-2N there are...
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    502

    Can you find the correct Mains plug to ship with...

    Can you find the correct Mains plug to ship with the amp ? Will the amp have an IEC inlet and the customer will supply a Mains cord set ?
  8. To build an amp from scratch you will need the...

    To build an amp from scratch you will need the following:

    A chassis. A pre-fabricated 'guitar amp chassis' will cost you. Other than that you can purchase a pre-fabricated box and drill holes in...
  9. The number 50 amp has lower plate resistors so...

    The number 50 amp has lower plate resistors so each side of the PI has lower gain. It needs more signal from the divider to balance the signal on the lower output tube.
  10. Replies
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    502

    Apparently the transformer has primary taps for...

    Apparently the transformer has primary taps for 100V, 120V, 220V and 240V.
  11. Replies
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    435

    What you are calling a bias adjustment doesn't...

    What you are calling a bias adjustment doesn't affect the bias of the output transistors, it has something to do with driver stage symmetry. No schematic shows the adjustment and there is no...
  12. Perhaps a picture would persuade you. Have you...

    Perhaps a picture would persuade you. Have you ever looked at how poorly a 12AX7 drives the tone stack in a 5F6A or Marshall 2203 ? It does OK until the signal gets really big. Then you start to see...
  13. The article has a factual basis, but it's...

    The article has a factual basis, but it's somewhat academic with no 'been there done that'. I don't think Rod plays guitar. What the article doesn't mention is that when you beef up the power supply...
  14. Is this the right schematic ? ...

    Is this the right schematic ?

    https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga15rvt.pdf
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    There is a way one vendor could rate a...

    There is a way one vendor could rate a transformer at 300mA and another could rate the same transformer at 600mA. It has various names, Marketing, Specmanship, lying, fraud, you name it. The specs...
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    The info you presented is confusing. Do you have...

    The info you presented is confusing. Do you have any pictures or links to other discussions? Is it really built on a Low Power Twin chassis (5 knobs) or the High Power Twin (6 knobs) chassis ? Are...
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    844

    It's rare to see a single rail Guitar Amp design...

    It's rare to see a single rail Guitar Amp design above 100W @ 4 Ohms.

    The earliest power amp designs used a driver transformer. You either used PNP germanium or NPN silicon output transistors....
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    844

    @jmaf, if you have a big stash of germanium...

    @jmaf, if you have a big stash of germanium transistors, they can be worth big buck$. Pack 'em up and send 'em to me.

    @TomCarlos, keeping with the KISS principle (Keep It Simple Stupid, or some...
  19. This is an ongoing problem. At an Amp show a guy...

    This is an ongoing problem. At an Amp show a guy from (IIRC) Red Plate Amps said they had problems with new tanks, got the vendor to use better wire by special order. I had a similar issue on a Two...
  20. If there is any question about the scope or...

    If there is any question about the scope or probes, connect both channels (via probes) to the same signal and compare the waveforms.
  21. Replies
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    1,013

    I feel your pain. Grounding on old Sunns is a...

    I feel your pain. Grounding on old Sunns is a nightmare. About the only thing done right is the cathode of the first triode is returned straight to the input jack ground (on some models). The laced...
  22. Ever notice that there are several holes where...

    Ever notice that there are several holes where the springs that suspend the reverb assembly from the outside chassis could be attached ? I've often wondered if that was the only difference between...
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    The B+ isn't much different between the two, 427V...

    The B+ isn't much different between the two, 427V vs 471V. The Blues Deville OT will tend to pull too much current. The Blues Deluxe OT is a much better match for the Blues Deluxe PT.
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    Is this one of those Peavey amps where all the...

    Is this one of those Peavey amps where all the power tube heaters are wired in series? Pulling one tube cuts off all the others.
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    There was a place in east Portland that sold some...

    There was a place in east Portland that sold some amp parts on the internet. They were a little hard to get in touch with for a while, then it was said the guy went on tour as George's amp tech....
  26. Thread: LTPI balance

    by loudthud
    Replies
    56
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    1,673

    I tried ground referenced inputs and transistor...

    I tried ground referenced inputs and transistor current source from the -80V bias supply. When the amp is in Standby mode, all the current goes through the grids. I ended up using a 30K resistor...
  27. Thread: LTPI balance

    by loudthud
    Replies
    56
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    1,673

    As an experiment, I'd like install a pot or...

    As an experiment, I'd like install a pot or switch to see how it sounds.
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    I don't disagree with what R.G. said above, but...

    I don't disagree with what R.G. said above, but ... you can't divorce the transformer from it's load, a speaker, unless you are talking about driving an OT with no load connected (not a bad...
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