Heathkit SP-2 vs. SP-2A difference?....no it's not mono vs stereo.

Discussion in 'Tube Audio' started by matt e., Sep 9, 2018.

  1. matt e.

    matt e. Active Member

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    I've seen at least one comment here and another at an online website that claim the SP-2A was the mono version of the SP-2. However; that conflicts with what I've seen in the Heathkit catalogs. All the catalogs show the SP-1 was the mono version that could be converted to SP-2 with a C-SP-1 conversion kit. The SP-2A doesn't show up in magazine ads until early 1960, but nowhere can I find what the heck made it an "A". Anybody know what the difference is and if there were any circuit changes?
    59_June_sp2_sp1.jpg
    June 1959 catalog

    I know Heathkit made other cosmetic only changes like when they went from tan to blue test equipment and like when they went from gold chassis amps to black chassis amps like the difference between an AA-40 vs AA-121. Is there some cosmetic difference between the SP-2 and SP-2A?

    Thanks, Matt
     
    Last edited: Sep 9, 2018

     

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  2. matt e.

    matt e. Active Member

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    March 1960 catalog page:
    60_March_sp2a_sp1a.jpg
     
  3. Dave C

    Dave C Super Member

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    Looks like 2 extra pounds to get the stereo version. or 5 extra pounds for the converter. Pretty well sums it up.
     
  4. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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  5. matt e.

    matt e. Active Member

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    Yeah, so you must have had 3 pounds of left over panels and knobs from the SP-1 to hit the dumpster.
     
  6. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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  7. matt e.

    matt e. Active Member

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    Great scans Mark. Do you see any difference between the 1960 "A" version and 1959 original version?
     
  8. matt e.

    matt e. Active Member

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    1959 SP-1 was "monaural", 1960 SP-1A was "monophonic". Maybe just a different manual? I can't see any real difference.
     
  9. AdamAnt316

    AdamAnt316 Collector of heavy things Subscriber

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    Monaural = Monophonic. Two different terms for the same thing. The stereo equivalent of "monaural" is "binaural", but that term is usually used to denote something else.

    As far as the SP-1/A vs. SP-2/A, I'm not entirely sure. I have a Heathkit pre which is apparently a SP-2, though it's missing its cabinet and ID sticker, so I'm not entirely sure. It's been awhile since I looked at it, but I believe it's essentially two different chassis bolted together in a 'H' fashion. I'll try and dig it out of the garage soon, and see what else I can tell you about it.
    -Adam
     
  10. darkblue94

    darkblue94 It wasn't me. Subscriber

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    Here's my SP-2, I honestly have no idea if it's a SP-2 or SP-2A, there's no indication on the outside. One thing is for sure though, I like it. :D
    IMG_0633.jpg
     
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  11. matt e.

    matt e. Active Member

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    Adam...right just semantics from early evolution of market. Only question is why Heathkit felt the need to change the model to "A". What was different about it? Must have been a reason, different circuit or maybe different power supply? Had to be something different. I picked up one of these that has both channels so I know it's an SP-2 something. I have the SP-2A manual so when it arrives I'll have to check through everything.
     

     

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  12. matt e.

    matt e. Active Member

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    Nice! Rolled the dice on the one I bought. Hope it turns out as nice as yours once cleaned up and restored.
     
  13. Sam Cogley

    Sam Cogley Last of the Time Lords Subscriber

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    There was a vertical faceplate available for the SP series for console mounting, but that doesn't seem to have anything to do with the "A" designation.
     
  14. matt e.

    matt e. Active Member

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    Received my SP-2 yesterday. 5 of the 6 tubes are "Heath by Mullard" with dates ranging from B8D through B8J. According to the online tube daters those tubes would've been made at Blackburn-1958-April through October. Of course they could have been purchased months earlier by Heath so I'm not sure if it means a thing in determining weather it was made as an SP-2 or SP-2A. So far I haven't found any deviations from the SP-2A manual. Anyway it's a nice virgin unit responding well to soap and a toothbrush.
     
  15. radioactive

    radioactive tube gear fanatic Subscriber

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  16. matt e.

    matt e. Active Member

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    :needpics:
    heath_mullard01.jpg
    heath_mullard02.jpg
    View attachment 1278942
    sp2_01.jpg
    sp2_02.jpg
    sp2_03.jpg
    sp2_04.jpg
    My good camera is at the office so this is best I can do with a dust filled Canon pocket camera: Best I can tell: Both 12AX7 = type code f91 with date codes B8I and B8J, Both 12AU7 = type code k61 with date codes B8D and B8E, Original 6267 = type code ?88 date code B8G, replaced 6267 marked IEC by Mullard type code 8Y1, date code B5D1 (1965).

    And my 1947 NC 173 :)
    nc173.jpg
     
    Last edited: Sep 11, 2018
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  17. gadget73

    gadget73 junk junkie Subscriber

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    And the matching National speaker, nice. Matching speakers seem to be a lot more rare than comm receivers of that era are.
     
  18. matt e.

    matt e. Active Member

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    No kidding. Paid more for the speaker than the radio and it's still wrong. Pictured is the 10" version. It originally came with a 6" that was in a case that matched the height of receiver. Hard to find in nice shape for reasonable $.
     
  19. gadget73

    gadget73 junk junkie Subscriber

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    I rebuilt an NC-183D for someone, it was a very nice piece. What burns me up about that thing, all the work I did on it and I know it has been sitting in the garage, untouched, in exactly the same place since I dropped it off. I know he hasn't even plugged it in.

    I have a Hallicrafters HQ-170 myself. Unfortunately its not a GC, so it doesn't really get much use. My GC is a 1940s EH Scott military radio. I paid about 50 cents per pound for it.
     
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  20. matt e.

    matt e. Active Member

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    Hallicrafters made some cool stuff. Have not owned many GC sets. I didn't go looking for the National, but I really like it. My wife wouldn't agree, but I think it's a piece of art and the machine work quality is outstanding. A guy in the area unfortunately had some serious health issues come up and didn't want to leave his family with having to deal with all his stuff so he had a big sale one weekend a few years ago. I heard some people showed up at 4am. I got there around 9 and the National hitched a ride home. He sold it to me for $65 and someone had already restored it. The only other GC outfits I have are a Hallicrafters Sky Chief and a Heathkit SW7800 I bought new as a kit. Oh yeah, I also have one of those Scott SLR's.....somebody got the tag so I'm not sure which model it is. Got it for cheap and regret buying it. If I wasn't afraid of herniating another disc I would put it in the truck and sell or give it away at the next meet.
     
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