schematics for a 60's Marshall 200 watt "pig"

Discussion in 'Let's Talk Vintage' started by rbehm, Mar 27, 2012.

  1. vintagekiki

    vintagekiki New Member

    Joined:
    May 1, 2008
    Messages:
    15
    Likes Received:
    5
  2. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023

    Dear Dan!
    Do you have a sound clip of your amp? Your experience is that its a rather clean amp, right? I however find my amp rather gainy as you have heard in my two sound clips. There is also a guy on you tube with a couple of clips of his pic, that sound similar to mine. Slightly differences I find on his circuitry which are not 100% original as one could easily see.

    I used an old gold top conversion with original PAFs (7,2k ohms) in my sound clip, so no high gain pickups

    Edit: Do you use an ultra linear OT or regular like the TH1498? I think this might be the reason

    plexi


    [​IMG]



    In the youtube clip I have two t88 in bias at 21mV each
     
    Last edited: Mar 18, 2016
  3. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Hi Plexi,
    Yes, the one I built sounds rather clean. It makes a great bass amplifier; clean and loud. The one difference between my amplifier and yours is that I have A LOT more filter capacitance in my amplifier. I can not remember why I did this; maybe because I didn't have any small value filter capacitors at the time. My first filter after the diodes is 330uf. I have 100uf for the screen supply and 47uf for P.I. and 47uf for the 1st 2 preamp tubes. I am willing to guess that this is why my amplifier sounds clean. I just bought some 16uf and 32uf capacitors and I am planning to change out the filters with these new capacitors. I don't have much in the way of recording gear but I will try to get a recording of mine up soon.

    When I first built my version of the "PIG", the original voltages I had were 640v for the plate supply and 358v for the screen supply, considerably lower than what was original. I am using a power transformer from an old Tektronix Oscilloscope that has many secondary voltages. I have since rewired the transformer so now I am getting 700v and 410v for the supply voltages.
     
    Last edited: Mar 18, 2016
  4. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    How about the OT Do you use an ultra linear OT or regular like the TH1498? I think this might be the reason for the gain difference as well. The guy on youtube also have a TH1498 OT

    best plexi
     
  5. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    My "PIG" has a regular OT, not ultra-linear.
    I built a Superlead with an ultra-linear OT about 25 years ago for a guitarist friend of mine and after about 5 years of playing it, he blew the OT, and the OT in that amplifier was rated for 200 watts. It was a very robust OT. Ever since then I no longer build guitar amplifiers with ultra-linear output stages; they tend to blow OTs. The reason I built this SL as ultra-linear is the same reason that Marshall used an ultra-linear output stage in the Major... It really simplifies the design of the power supply. Live and learn!:)
    My "PIG" has a 5000 ohm primary OT that I halve the impedances on when I use KT88 tubes. So with KT88 tubes, I use the OT as a 2500 ohm primary to 8, 4, 2 ohm secondary. I originally installed EL156 output tubes in this amplifier, which require a higher load impedance; this is why I used a 5000 ohm primary OT. The EL156 tubes sound very good; they are true pentodes like the EL34. In fact they are basically a EL34 but with a 50 watt dissipation per tube.
     
  6. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    I also have the Electro-voice 200 watt transformer set which are equivalents to the original "PIG" transformers. They were from a Sound City amplifier. When I build another "PIG" with these transformers, I will make everything "stock", to the best of my knowledge, to the original "PIG" circuit.
     
  7. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    This is very interesting, only filtering difference?


    Here is the other pig on Youtube, same transformer as mine TH1498...



    The schematics of the PA the Pig have the dual core transformer. That schematics doesn´t show a ultra linear OT either. As a matter of fact I have never seen any picture if a Pig PA or regular with an ultra linear OT that was original. The Pig amps were designed by GEC and not Marshall.

    Marshall then redesigned the 200 into the Major (6 knobs) and they had ultra linear OTs. I am starting to believe that a Ultra Linear the pigs never existed and they used regular trannies and the UL came with the redesigned major.

    Marshall-Major-PA-PIG.png
     
  8. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Ultra Linear OT was only on the Marshall Majors, never on the "PIG".
     
    pleximaster likes this.
  9. vintagekiki

    vintagekiki New Member

    Joined:
    May 1, 2008
    Messages:
    15
    Likes Received:
    5
    Unfortunately I have to disappoint you. Schematics you gave is incorrect.
    - Cathode tubes connected to the output voltage of +450V (point C)
    - Screen grid over 1k resistor connected to the cathode
    There is simply no logic.
    There is no magic to amplifier in this circuit (anode connected to +650V and the cathode connected to +450V) can work.
     
  10. Michael RT

    Michael RT Well-Known Member VIP Member

    Joined:
    Jan 27, 2009
    Messages:
    9,963
    Likes Received:
    5,597
    I like this video.
    Definitely one of the nicest video's on youtube of the Pig I've ever seen.
     
  11. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    Thanks for clarifying this! I have seen multiple people saying the pig could have ultra linear OT and I have three book stating the same some say they only had ultra linear OT

    I guess someone mixed up the pig with the major and after a few misquotes especially on the inter net it "becomes the truth"... :)

    plexi
     
  12. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Hi Plexi,
    I think a lot of people get confused about the two different models. I have even seen the confusion on this forum and even this very thread! I would like to know the "official" reason why Marshall discontinued the 3 knob "PIG" and started making the 6 knob "MAJOR". Personally, I think the reason is that musicians didn't like the way the controls operated on the "PIG". I don't know if you have noticed on your amplifier, but if you adjust one knob, you have to slightly adjust the other two knobs to get "the Marshall sound" working correctly again. It's like all 3 knobs are kind of interacting with each other; if you adjust one, you then have to adjust the other 2 knobs.
    When are you planning on letting Johan Play your amp? I'd like to know what he thinks about the amplifier.
     
  13. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Vintagekiki,
    Yes, the output section of that schematic is incorrect, as are some of the voltage values. It would be great if you and Pleximaster could correspond and draw a corrected schematic for the Marshall 200 "PIG".
    With the Partridge TH1498 Power Transformer, the Marshall 200 PT secondary connections should look like the following Sound City 200+ schematic:

    sc_lb_200_schemo_right.jpg
     
  14. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    This is the inside of my pig look like now.

    [​IMG]

    I have followed Vintagekiki schematics with the exception of and added 47pf phase inverter capacitor between the 82k and the 100k resistor, as in a super lead, your suggestion Dan. I have also added two extra internal fuses one at the choke and one for the B+
    I also have 1,8K 5 watt resistors on the octal tube sockets instead of 1k 5 watts

    The rectifier section is done as you suggested (I didnt move the diodes I just used jumpers under the board, two diods on the big board are not used) PICT0001.JPG

    For the biasing i used the Hiwatt dual trimpot setup (Didnt need the voltage doubler with the GEC tubes they matched the circuitry well) I use two 47uF cans instead of one 100uF. The two trimpots I´ve used are not 10k as in the picture but 47k
    DR_200wPS.gif

    And using the dual trimpots as i Dan´s picture (Great illustration for dummies like me :) )

    PICT0007.JPG

    I hope this info is enough for anyone who like to try this or do a new schematic with the TH1498 transformer

    plexi
     

    Attached Files:

    Last edited: Mar 20, 2016
  15. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Very nice work on your Marshall 200. Have you played guitar any more with this amplifier? What are your impressions of the sound of this amplifier compared to a 1968 SuperLead?
     
  16. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    Thanks Dan!

    Yes I played it a lot! It´s so much fun! It´s Marshall sound but something different. The interactive knobs are cool. The table volume is sort of bright channel on a SL and the Bass volume is the normal channel end then you have a master volume that are like both channels jumped in a way. The KT88 is different sounding from el34 and i feel the connection here to my park75 that have kt88 as well.

    This amp has possibly the best rhythm guitar sound I ever heard so huge and fat but at the same time well defined and clear even up to were I mas both the treble and master (the bass can mush it up a bit)

    for soloing it is also great having this fat and full sound however shredding is not for the pig as the attach (is good) but its not as fast responding as a 68SL the. I love the sag in this amp (I have lower filtering than you have) but its too much for super fast shredding.

    Johan is coming Tuesday for a demo.

    Yesterday I tried a super wah (for the first time ever, got it years ago and never hooked it up) into the pig and it sounded so cool!

    I run it with two kt88s and (8 ohms from amp into 16 ohm cab) for practical reasons and that I have delicate 25 and 30 watts greenback speakers that I don´t want to blow up. This alters sag and sound a bit but I don´t think its that a big deal.

    best regard plexi
     
  17. vintagekiki

    vintagekiki New Member

    Joined:
    May 1, 2008
    Messages:
    15
    Likes Received:
    5
    Hi Plexi, Day and all pig lovers

    Compare schematics power supply from the image
    http://www.marshallforum.com/index.php?attachments/marshall-major-pa-pig-png.34437/
    with schematics power supply from the image
    http://www.marshallforum.com/index.php?attachments/sc_lb_200_schemo_right-jpg.34447
    obviously there is a difference in the configuration of transformers Partridge TH1498 and 7032-6 (Dual core Partridge).

    Transformer with full wave rectifier has both high voltage secondary windings with 3 wire each, and all electrolytic capacitor (for + 700V and 450V +) are connected in one point to chassis. It can be seen from images
    http://www.rig-talk.com/forum/download/file.php?id=11908
    http://www.marshallforum.com/index.php?attachments/image001-gif.34392/

    Transformer with with bridge rectifier has both high voltage secondary windings with 2 wire each, and the power supply for the anode (+ 700V) is connected to the "floor" with the power supply g2 (+ 450V)

    I study the images from the links listed in
    http://www.marshallforum.com/index....60s-marshall-200-watt-pig.40968/#post-1405857
    how would draw power supply schematics for both types of PT
     
  18. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    Hi again,
    I just saw this...
    My KT88s are biased at 40ma each.
     
  19. pleximaster

    pleximaster Well-Known Member

    Joined:
    Feb 6, 2012
    Messages:
    1,164
    Likes Received:
    1,023
    I have them lower but not that low I have them at 31mV. The 2 and 3 are too close on my keyboard and I have fat fingers! :)

    35watts for a kt88 at 725V at 70% is (35/725)*0,70 = 33,8 mV

    So I sat them around 31mV

    best plexi
     
  20. danfrank

    danfrank Active Member

    Joined:
    Mar 5, 2015
    Messages:
    420
    Likes Received:
    131
    I thought KT88 dissipation is 42 watts?
    Or are they 35 watts dissipation each?
     

Share This Page