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mike stehr

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Posts posted by mike stehr

    Cannabis at Bargain Prices

    in Lounge

    Posted

    23 hours ago, grasshopper said:

    ...on the upper end of the market, idiots are paying $25/seed....that is per ONE seed.

     

    Seems a bit risky...what if the seed dies? 

     

    Most grow operations clone their strains of plants.

    Unless it's autoflower, which grows from seed, has a quick grow time from seed to flower, and is mostly grown on outdoor operations.

    • Like 1

    Tube amp recommendation

    in Talkin' Tubes

    Posted

     

    12 hours ago, Jefe said:

    watcha got?

    BTW, the two amplifiers recommended aren't integrated tube amplifiers.

     

    I have two integrated tube amplifiers that are vintage. A Lafayette Stereo 250A EL86 push-pull, and a HH Scott LK48B.

    Both sound rather good for what they are.

     

    I haven't heard any new offerings of low watt integrated tube amplifiers.

     

    Being an integrated amplifier, you want a phono stage...correct?

    • Like 1

    Is mild hum normal?

    in Technical/Restorations

    Posted

    27 minutes ago, seti said:

    All transformers hum or have potential to hum as they all vibrate.. I made a jig to clamp down transformers. I've cured it sometimes with my funky clamps but also with putting rubber washers under the transformers and really clamping them down.. This can be a bugger. I work on one amp that it was so bad I couldn't get it to go away no matter what I did to it..

     

    If one has the end-bells detached, you can sometimes get away with using a small piece of wood tapped into the winding/core area...depending on the transformer.

    Separating the OPT from the amplifier

    in Talkin' Tubes

    Posted

    Imagine the length of the OPT primary wire, and B+ (or wires for a PP amp) going from the tube plate and or plates to the location of a speaker.

    A push-pull output transformer may or may not have feedback from a secondary tap to the cathode of the driver tube.

    So one would have to run a longer wire for feedback from the OPT secondary from the location of the speaker, back to the amp.

     

    Quite a few OPTs have a chassis ground. There's another wire to run from the OPT back to the amplifier.

    Doesn't seem practical in the least IMO, and I have no idea what advantages there would be from using high voltage primary wires as glorified speaker leads.

     

    I have never tried it however.

     

    What advantages do you think of having the OPT near a loudspeaker?

    • Like 1

    The long awaited "Little Sweetie" mono SETs

    in Talkin' Tubes

    Posted

    3 hours ago, John N. Lumley said:

    Hi Mike,  great idea!

     

    Actually, the idea was from a friend of mine who designed the circuit and coached the build for me.

    The PS transformer is a Gramer television transformer, with a 10-12 Awg heater winding for the 6AU4.

    A 36uf Mallory oil is the first capacitor in the supply, with a 4 Henrie choke, a 100uF Sprague Atom with another Mallory 36uF oil cap in parallel with the Sprague.

     

    And I thought this audio amp power supply using 6AU4 for full-wave was just a bizzaro one-off...and it turns out Marantz did it with a commercial amplifier.

     

    Pictures of your Tube Amplifiers

    in Talkin' Tubes

    Posted

    A retired audio engineer friend of mine gifted me this Zero Zone Grounded Grid line-stage circuit and power supply last winter.

     

    All I needed was a PS transformer and so I ordered one. Then I ended up blowing up a mosfet in the first PS he gave me, and had to buy another.

    I need to point out these ZZ grounded grid line-stage PCBs have the silk-screening incorrect for the 22uF 450volt Epcos decoupling caps.

    The ground line is backwards on the positive side.

    If you notice, the caps are in backwards, which are oriented correctly. Keep that in mind if one desires to purchase these GG boards.

     

    The original output capacitors were some green supposed Vishay brand metal polypropylene. They look rather cheap...

    I had the 1uF Jantzen Silver Z-caps sitting around, so I swapped out the Green caps for the Silver Z-caps.

     

    Never thought my 2A3 amp would benefit from a line-stage, I always used a passive volume control. And I always thought that I had bloom, depth and width.

    The retired AE replied that you won't get bloom, depth and width from a passive volume control...you need tubes with gain.

    Lesson learned. Ann and Nancy Wilson almost made me cry with their harmony...

     

    I'll try my Altec 345A next with ZZ GG line-stage.

     

    Mike

     

     

     

     

     

     

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    • Like 4

    Eico ST-70

    in Talkin' Tubes

    Posted

    I bought a Eico ST70 at ST. Vincent DePaul in the as-is area for 3 bucks...back in 2007-08...

    All the original tubes, all testing strong. The clerk,  (jail work release) had no clue what it was.

     

    Unlike Henry, who wants to rehabilitate and restore his ST70, I promptly ripped mine apart wanting to build a power amp out of the unit.

    Getting over my head, I ended up with an oscillating mess. Gave up, and it's been on the shelf ever since.

     

    I still want to build a power amplifier out of the unit, but maybe using 6L6 instead of 7591.

     

    post-6643-13819297961982_thumb.jpg

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