Jtm 100 Super P.a. Amplifier

Discussion in 'Let's Talk Vintage' started by Starbangledspanner, Feb 14, 2017.

  1. Starbangledspanner

    Starbangledspanner New Member

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    Greetings from rural England. I have had the amp mentioned above since 1979 I think, when I bought it for £25 of an old school mate who had used it in the school (rock) band for his bass guitar. I used it for the same purpose but only ever in rehearsals for my brilliantly talented band (apart from the bass player). When it all failed the amp from then on lived in my bedroom until marriage then it lived in my "toy" room where it gets played through with my now 6 string B.C. Rich Mockingbird through a Zoom pedal. Before my mate had it I have no idea how, when or where it was used. I have done absolutely nothing to it apart from switching it on and using it. It did come with a cover but I am struggling to find in my loft.

    Now with a house move pending and my dreams of stardom fading, I began to think of selling my amp. I thought it might be worth something being old an all, but it appears it could be worth much more than I thought. It all depends it seems from reading all these forums and anything I can find on the interweb, that it needs to be in original condition or as near as possible.

    This is hopefully where you nice people come in. I am by trade, an electrician but electronics leaves me baffled. I have taken a multitude of pictures from all angles and present them here and I hope that you can be so kind as to tell me how original it is.
    Regards
    Geoff
    Img_3130a.jpg Img_3130a.jpg
     

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  2. neikeel

    neikeel Well-Known Member

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    Hello and welcome
    The good news is that the amp is very original. There are only a couple of the filter capacitors that have been replaced (the Spragues) and a couple of resistors to bias for your GEC KT88s, the amp would originally had x4 GEC KT66s, which can be had but are expensive. The KT88s are pretty robust tho'.
    The PA amps are not worth as much as the guitar amps. These get the most £ (well $ really) followed by the Trems and then the PAs.
    A guitar amp like yours would be worth over £5k if you were prepared to carefully prep and box etc for shipping to the US. Whether a PA amp gets there will depend who is looking.
    I would do nothing to mod or 'fix' the amp if you are going to sell. Photo bomb and put in the classifieds here and at Vintage amps (plexipalace) where a lurker may well contact you with a decent offer (don't get lowballed - unless it is by me!!).
    Good luck
     
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  3. liontato

    liontato Well-Known Member

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    :cool:That is quite a treasure. You should hold out for good price. I don't have the money right now but I do have a couple healthy organs I could donate!
     
  4. Starbangledspanner

    Starbangledspanner New Member

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    Thank you for your quick replies. I have no intention of doing anything to the amp. I have only opened it up to photograph and clean some of the dust away.
    I am actually coming to the U.S. in late May for a family wedding as some poor girl has fallen for my nephew who lives in Virginia.
    I didn't realize about the valves being different to the originals, but somewhere among all the stuff I have been reading, I came across a comment about only driving two of the channels to give it more "grunt" so I assumed that was the deal with that.
    My organs are all fully functioning though my liver is borderline.
    Geoff
     
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  5. AlvisX

    AlvisX Well-Known Member

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    Thanks for sharing the pics !
     
  6. neikeel

    neikeel Well-Known Member

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    The amp has 4 pairs of inputs (2 per pre amp valve for v1 and v2) v3 is a gain stage and cathode follower (for the EQ section). V4 is the phase inverter to drive the output valves.
    Having two output valves I nothing to do with any of the above. It is a cost saving measure Normally I would caution against it but the OT has a big primary ratio and GEC KT88s are the dogs wotsits so no issue.
    Disconnecting the grid wire to take v1 (channels 1 &2) out of circuit is a common mod to give a bit more gain but having 4 channels and a stack of pedals can be fun.
     
  7. Appetite4distortion

    Appetite4distortion Active Member

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    Cool amp, I have ser #7159, they look twins
     
  8. danfrank

    danfrank Active Member

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    Nice amp! The 2 KT88s match well with the output transformer in that amp. If you get it re-tubed, keep the old tubes as they are worth money. Honestly though, those 2 original G.E.C. KT88s will hold up better to the high voltages the power transformer makes (550-600 volts) than any current production tubes made today.
     
  9. Lo-Watt

    Lo-Watt New Member

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    Wow! 7200$ USD?? That's awesome wonder what my 69 SL is worth???
     
  10. neikeel

    neikeel Well-Known Member

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    Who mentioned $7200US?
    Your 69 SL value will depend on plexi vs metal panel, originality and condition. I have seen people ask that much but never achieve it!
     
  11. soundboy57

    soundboy57 Well-Known Member

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    I will give you 10 times what you paid for it....PM me :)
     
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  12. Lo-Watt

    Lo-Watt New Member

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  13. Lo-Watt

    Lo-Watt New Member

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    5k pounds equaled 7200$ usd
     
  14. Lo-Watt

    Lo-Watt New Member

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    I'll never sell mine but it is all original dated Sept 20, I changed the filters and power cord, all else unchanged. Metal panel. Sounds glorious cranked. I wouldn't mind getting this one though!!
     
  15. neikeel

    neikeel Well-Known Member

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    Sadly not where I am! More like $6,250. Makes US-> UK imports painful! Had to stop buying US made stuff.
     
  16. Starbangledspanner

    Starbangledspanner New Member

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    The wife has been busy planning what to do with "her" new found fortune. I realise that I will not get the kind of money it would command across the Pond but still a lot more than the few hundred I thought initially.

    May I ask permission to use some of your descriptions when I do get around to creating an advert to sell?

    Looked on eBay for the price of the valves. Wow, even the little ones go for silly money. I remember as a kid being sent to the valve shop, which was quite a walk, to get replacement valves for the black and white TVs we had in the sixties. they were only a few shillings and we used to have a great big bag of them. I remember them getting thrown away, what a waste.

    I am now frightened to turn it on now I know it's worth, but I will. I have only ever cranked it up to the max a couple of times, I have two 12" Goodmans speakers in a hand made cabinet that I paid £10 for when I got the amp but they were blown so I got them re wound in Dalston, London buy some old boy for another £10 the pair. Things fell over on the shelves and the disply cabinets when I turned it up full and I thought the glass doors would shatter as they rattled so much so I only go loud enough to annoy the people next door.
    Geoff
     
    Last edited: Feb 15, 2017
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  17. neikeel

    neikeel Well-Known Member

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    Where are you Geoff?
     
  18. Starbangledspanner

    Starbangledspanner New Member

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    I live in Norfolk, England.
     
  19. neikeel

    neikeel Well-Known Member

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    I'm in Suffolk.
     
  20. Starbangledspanner

    Starbangledspanner New Member

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    My little sister lives in Ipswich. I'm near Kings Lynn in fact almost the last village before Lincolnshire starts so proper rural.
     

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