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Another major find by the audiophile scrounger. ... The final block, the amp(s).

  1. skwoodwiva
    So in my quest to get back to where I was 25 years ago, I landed a scrap yard find of unique fratuers for bi amplification of my 206 reference monitors.

    Much more to say. I will make this my DIY home thread & consolidate all projects here

    How about class a bias for these ?

    Those are simi complimentary BP transitors(?). As there are 2 different of the same size & an oddball smaller one. .. I did not examine it long.

    TFE perf boards anyone? https://www.diystompboxes.com/smfforum/index.php?topic=60933.40


    https://tubeamplifierparts.com/watts-store.html/#!/Watts-Perf-Board-3-125-x-14/p/65263243
    ALL THAT fiberglass resin, it is as bad/ worse than pvc as to diaelectic absorbtion.:)

    I did this to a Sony Ta-n90ss just add sinks as needed. DSC_0022.JPG DSC_0014.JPG DSC_0011.JPG
     
    Last edited: May 1, 2018
  2. skwoodwiva
    Some quick do up of another find.
    DSC_0037.JPG

    The Damar takes a peak out out my woodies. 9v battery amp
    W/ tone & volume.

    Sounds not bad for amp building music
    DSC_0039.JPG DSC_0040.JPG
    See hoe the amp modules & chip leads will fit within the box & fins will be exposed.
    60 v rails (24 ac) vs 75 (36) of original , a no brainer. DSC_0042.JPG

    My 206s are next these are guinea KRK , get the boards that will actually fit in the 206s.
    Well bent 90* at the transistor leads. Heat sinks on the back all "Professional looking" for the vintage CBS monitors.
     
    Last edited: May 4, 2018
  3. skwoodwiva
    Very similar to the Sony T/an boards, simi complimentary AB. With bias adj. pots. Class A here we come. DSC_0051.JPG

    What a find I bought 2 for $40 scrap.
    I found out while at the yard, the controlled gizmo portion never worked w/o a dealer only piece of equipment .
    What a gem to mod. All descrete, not a chip or op amp in sight! One amp is 300w AB. If I learn to bridge 2 modules , I could use 8 boards &
    Go balanced getting ~100 w class A stereo.

    So I am asking any Guru here if this board can be bridged into a 2 board stereo pair?
    Then each pair would drive a balanced configuration.

    I think it is the Quasi-complementary design below.

    From https://en.wikipedia.org/wiki/Sziklai_pair
    Quasi-complementary output stages
    Historically, designers frequently used the "quasi-complementary" configuration, which uses a Darlington push pair (i.e., two NPN transistors) and a Sziklai pull pair (i.e., one PNP and one NPN transistor). This configuration, which uses three NPN transistors and one PNP transistor, is advantageous because while the first transistors and the most common small signal transistors for decades were PNP Germanium devices, silicon PNP power transistors were slower to develop than and have historically been more expensive than their NPN counterparts. Alternately, if a germanium PNP device were used, it would have significantly different characteristics. In the Quasi-complementary topology, the performance of the lower pull pair, which used a single NPN transistor, more closely matched the performance of the upper push pair, which consists of two NPN transistors and an identical power device.[3]

    While for decades the Quasi-complimentary output stage made sense, recently PNP and NPN power transistors have become roughly equally available and have more closely matched performance characteristics, and so modern audio power amplifiers often use equivalent topologies for both pairs, either both Darlington emitter follower or both Sziklai pair.[3][4]
     
    Last edited: May 4, 2018
  4. skwoodwiva

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