Makeshift preamp for ST-70: a Rod Elliott design?

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Makeshift preamp for ST-70: a Rod Elliott design?

Postby LowRedMoon » Wed Feb 01, 2006 7:09 pm

Hello, good tube heads! This is officially my first post.

I just ordered an ST-70 off of eBay for $250. This will be my first amp of this quality. The simplicity of design, good reports and vast community support for this amp are why I've picked it. I'm pretty excited about it!

I'm trying to select a decent, cost effective preamp for this baby. Gradually, I'll upgrade into something truly decent, but for now, due to cost limitations, it looks like I may be stuck with a SS design.

I'm considering this one by Rod Elliott. http://sound.westhost.com/project88.htm It provides around 9dB of gain and looks pretty straightforward.

Unless any of you good people can guide me toward a more suitable design, I'll get started on this one. Any suggestions are quite appreciated! Thanks!
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DIY preamp

Postby Shannon Parks » Wed Feb 01, 2006 9:10 pm

Hi LowRedMoon,

Welcome and congrats on your ST70 pickup - it's a fantastic amp. As to your preamp question:

1) Are you looking for a DIY? Phono needed, too? Pricerange for project? A single twin triode preamp isn't difficult or expensive.

2) If you just need a preamp fast/cheap, a few of us really like the Adcom GTP series. The GTP-350 and GTP-400's can be had for around $100.

Shannon
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Postby LowRedMoon » Wed Feb 01, 2006 9:23 pm

Thanks for the reply, Shannon.

I'd prefer to build the preamp myself. This is part of my self-teaching program. I've heard good things about the Adcoms, but I can't bring myself to buy one because their all-black look gives me unpleasant flashbacks of the days when Lo-Fi 80's consumer-level equipment was all I could afford. I'm usually not picky about looks, but I can't seem to get over this one.

I'd like to keep my costs for a preamp betweek $100 and $200. I know this isn't much, but it's really all I can spend for a while.

I do have a phonostage, so this wouldn't be a necessary inclusion.

I'd love to hear about a twin triode design that you think is particularly good.

Thanks!

Adam
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Postby MarkC » Wed Feb 01, 2006 10:32 pm

I built this one to use with the ST-35 and St-70. It's a triode connected EF86 design that was pulled from the Svetlana home page. I did a lot of research before I settled on this one and to me, it sounds really nice with these amps. Easy to build and inexpensive.

http://kevinsgarage.50megs.com/images/ef86prebuild.html
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Postby EWBrown » Thu Feb 02, 2006 7:21 am

There are a few tube linestage circuits presented here on Gary Kaufman's site:

http://www.the-planet.org/

as well as some SET and PP amps, nixie clocks, and tube and trannie data, Dynaco data, etc

/ed B in NH
Real Radios Glow in the Dark
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Pre-amp

Postby leadtower » Mon Feb 13, 2006 6:38 pm

Hi LowRedMoon; I just noticed your post concerning the Rod Elliott pre-amp and thought I might offer some thoughts since I am in the middle of building one. I made the mistake of buying black-gate caps and riken resistors which it so happens don't fit on the PC Board. I am making them fit but truthfully I should have just used standard parts from mouser. The PS is completed and works beautifully. I used a Hammond Toroidal Trans and larger reservoir caps.
The take-offs are very small so what I did was used the clipped leads from the Rikens as a tie-point for the inputs and outputs.
As soon as I finish up the chassis wiring the unit should be good to go. I would be interested in your thoughts on the pre if you choose to do it.
I also have a Bottlehead pre-amp kit that sounds darn good with the ST 70 and that is pretty inexpensive also.
Hope all this helps.
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