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    DIY ST70 from scratch?

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    DIY ST70 from scratch?

    Post by Guest on Wed Dec 30, 2009 9:31 pm

    Hey, I've always been interested in ST-70's but I still haven't gotten around to it. I've built scads of S.S. amps and helped in their designs, but I've always wanted to build (and own) an ST-70.

    These VTA boards sound like a perfect place to start. But are all the other parts available at reasonable prices? I'm thinking of the 3 transformers in particular. I'm a bit frugal (or maybe my wife is and I'm just afraid affraid of spending money). I guess the tubes can get a little pricey too. What's everyone's best advice to slap one together really cheaply but not cut any stupid corners?

    And how the heck do you cut socket holes into a blank chassis? scratch

    I don't care (not even a little) if it looks like an authentic ST-70. It will look great when I'm done. I just want it to sound great, which I'm sure it will.

    ..Todd

    avi.inc

    Posts: 53
    Join date: 2009-08-03
    Age: 61
    Location: L.A.

    Re: DIY ST70 from scratch?

    Post by avi.inc on Wed Dec 30, 2009 10:32 pm

    http://www.tubes4hifi.com/bob.htm

    Guest
    Guest

    Re: DIY ST70 from scratch?

    Post by Guest on Wed Dec 30, 2009 10:52 pm

    Yeah, I read that. The boards are a great place to start, but I want to do the rest myself. It was the rest I'm inquiring about. Thanks anyway.

    I'm not a buyer, I'm a builder. But PCB's are best left to experts when you're working with foreign topics. I'll buy those from Bob. The price is great.

    ..Todd

    tomlang

    Posts: 29
    Join date: 2009-08-12

    Re: DIY ST70 from scratch?

    Post by tomlang on Wed Dec 30, 2009 11:56 pm

    I've done one ST70 with parts from various sources with the VTA board and it was the best sounding amp I ever had. There is probably a dozen or so drive boards out there, and in my opinion, that is where 80-90% of the engineering and the parts of the amp reside. For the second ST70-type amp I want to build I am going to use this board http://www.diytube.com/phpBB2/viewtopic.php?t=3643

    Another thing...unlike SS gear, the transformers are expensive and represent about 50% of the cost of the entire amp or more! While your mileage may vary, I have not found a way to build an amp like this for less than $500 using new parts.

    Guest
    Guest

    Re: DIY ST70 from scratch?

    Post by Guest on Thu Dec 31, 2009 12:33 am

    So what are the options for transformers? How many different vendors sell them and who are they? I'll be doing some shopping around, obviously. Does Hammond still make them?

    Aside from the chassis (which can obviously vary from using cake pans to buying replica ST-70 chassis) what costs so much it adds up to $500? I see the tubes are about $25-75 for 'economy' match pairs, and the caps and resistors can be a wide range (those I know well enough). So... $300 for transformers? Sounds a bit steep for economy models. No?

    ..Todd

    arkivel

    Posts: 6
    Join date: 2009-11-11

    Re: DIY ST70 from scratch?

    Post by arkivel on Thu Dec 31, 2009 3:15 am

    I would assume the high cost of some parts is a reflection of the fact that these are reproduction items that are manufactured in relatively small runs. Setting up tooling is not cheap. It requires a substantial monetary investment.

    You can probably find cheaper alternatives for transformers and chassis elsewhere but you will definitely spend more of your time putting them together and you will need expensive specialized tools to cut a metal chassis. You should also consider that a dynakit based amp will have much better resale value than a hand built creation from an unknown builder.

    I think for the money involved you can't go wrong with these kits. You will not find a better amp for the money that comes assembled and you are getting a proven design with tons of support.

    Guest
    Guest

    Re: DIY ST70 from scratch?

    Post by Guest on Thu Dec 31, 2009 1:06 pm

    arkivel,

    I have no doubts that you are 100% correct on all counts. But I'm not interested in resale value or any of the other concerns you mentioned. I can see I've come to the wrong forum for this now, with apologies. Bye.

    ..Todd

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