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Old 30th November 2004, 06:19 AM   #11
Wodgy is offline Wodgy  United States
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As a first project, I second the recommendation for the S5 Electronics kit amp that someone else has already mentioned. It's a nice little amp, and it's well engineered in the sense that the sound is more than you'd expect from the modest sum of its parts. The designer of that kit is George Fathauer, who was one of the pioneers of color television and also founded Antique Electronic Supply. You can find a review of the S5 Electronics amp from a sound perspective on the AudioXPress website.

Tube gear doesn't have to be expensive to sound good (in that sense it is more forgiving than solid state), and to be honest, I agree with you that some other kits are overpriced. Welborne uses boutique parts and then adds on his customary large price markup to his kits. The Bottlehead kits are reasonably priced given the level of sound you get and the hand-holding you can expect during assembly from the online forum, but you can do the same or better for less if you buy the parts yourself.

If you're just looking for a good introductory amp project and not necessarily a kit, this page is really good:
http://boozhoundlabs.com/howto/
The author essentially takes you from start to finish in designing and building a single-ended tube amp using inexpensive but quality parts (6V6 power tubes, Hammond 125 transformers), without assuming you know anything about tubes to start with. That particular amp is only about 2W per channel, but if you want something more powerful you can apply the same principles to designing a more powerful SE amp.
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Old 30th November 2004, 06:35 PM   #12
azira is offline azira  United States
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Quote:
Originally posted by jpchleapas

Actually Doc B's amps are rather inexpensive by comparrison to the Welborne amps I own. If you break down on paper the cost to build an amp from scractch it is not really that inexpensive at all to DIY one.
Thanks. I guess I'm not looking so much for a kit as a beginner schematic and a parts distributor. There was a link given earlier that had a straight forward 13EM7 1wpc and also a PP 3wpc version that looked simple enough to start with. I'll look into that as well as 6V6 one. Looks like I might be able to use allelectronics for some of the xformers.

One more question: The surplus shop I go to every now and then has a box full of random tubes, most of the numbers don't seem like the standard ones I see all the time (12AX7, EL84, 6V6, etc). Are tubes flexible like MOSFETS in that pretty much most of them can be used, it's just a matter of the params, load lines, and how well they actually work...

Thanks everyone, the info has been great.
--
Danny
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Old 30th November 2004, 07:19 PM   #13
SHiFTY is offline SHiFTY  New Zealand
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Quote:
One more question: The surplus shop I go to every now and then has a box full of random tubes, most of the numbers don't seem like the standard ones I see all the time (12AX7, EL84, 6V6, etc). Are tubes flexible like MOSFETS in that pretty much most of them can be used, it's just a matter of the params, load lines, and how well they actually work...
Sometimes. Many radio and tv valves are totally unsuited for audio however. (variable mu, rf tubes etc.)

I would take a look, you might be lucky...
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Old 1st December 2004, 05:15 PM   #14
azira is offline azira  United States
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Quote:
Originally posted by SHiFTY


Sometimes. Many radio and tv valves are totally unsuited for audio however. (variable mu, rf tubes etc.)

I would take a look, you might be lucky...

Any tips on how I might be able to distinguish something usable for audio vs not suitable out of a bin of tubes, they're all still in boxes although old looking...
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Old 1st December 2004, 08:39 PM   #15
Sherman is offline Sherman  United States
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Quote:
Originally posted by Kofi Annan
If you want a cheap kit, the S5 Electronics Kit might suffice. I actually have one of these, but I have yet to assemble it....

...Its an 8W push-pull job, so it may have enough power to push more inefficient speakers.
...

And now, back to world peace...

Kofi

Quote:
Originally posted by gmilitano


I have also purchased the S5 kit and have yet to build it. S5 was very friendly. It took a while for the kit to arrive as a result of border/customs delays in Canada.

I will also try have it together by this weekend and will post my initial listening results.

Cheers,
GM.

Get to work on those you two! It really is a nice little amp and nothing I've seen touches it for the price. (I have one and it is built!) Also, do use Voltsecond's site for reference (mentioned in the Secretary General's post). Lots of good stuff to make it sound even better at very low cost.

The amp I built actually had a few of Voltsecond's mods designed into the pc board already so it appears they do pay attention and upgrade occasionally. Mine also came with ceramic sockets.

For a beginner to tubes this is a very nice introduction. And the power is pretty good as I initially was using it with a pair of Advent/1 speakers (I think they are about 87db/1W/1M). While it wouldn't make your ears bleed it did a great job at more normal (for me) listening levels.
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Old 1st December 2004, 08:56 PM   #16
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Hi,

Quote:
Any tips on how I might be able to distinguish something usable for audio vs not suitable out of a bin of tubes, they're all still in boxes although old looking...
Best thing to do is to jot down the types you don't know much about and look up their data in a manual.

There are several well respected manuals online from RCA, Sylvania etc.
Then there's Duncan Munroe's database as well....

Naturally you'd still have to understand what these data mean but quite often the intended use of the tube gives you a clue.
Not that many tubes were made with the exclusive use for audio in mind so that still leaves a vast choice of tubes.
Classes of special purpose tubes such as carcinotrons, thyratrons, photomultipliers, etc. can safely be discarded for any normal audio applications.
Receiving tubes are often fine but not all are suitable.

DUNCAN AMPS.

Cheers,
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Old 1st December 2004, 10:33 PM   #17
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Quote:
Originally posted by Sherman


The amp I built actually had a few of Voltsecond's mods designed into the pc board already so it appears they do pay attention and upgrade occasionally. Mine also came with ceramic sockets.
Hi Sherman,

My kit also came with ceramic sockets, so they have adressed the melting socket problem.

I am curious, which of the Voltsecond's mods were included with your kit?

Regards,
GM.
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Old 9th May 2006, 08:25 AM   #18
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Default Need to learn the basics on tube systems

Sorry guys,

I am fascinated by the discussion of tube preamp/amp systems and the downstream speaker needs BUT I get lost in the terminology for the hardware.

Can anyone recommend a good source for developing a basic understanding of the "tube" space so I don't waste your time with naive questions that can be easily addressed elsewhere?

Thanks in advance,
StuHaugen
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Old 9th May 2006, 04:55 PM   #19
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www.diyaudio.com has always taught me a lot. believe it or not, every question you could ask, has been asked at one point or another! just start readin'. good luck
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Old 13th May 2006, 07:24 AM   #20
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Default Getting good background on building

YOu can't do better than Morgan Jones book:

"Valve Amplifiers". He has pretty much everything there.

With respect to boxes full of tubes at yard sales--best to stay away from them unless they are the standard audio type.

Build your fist project off of one of the projects on this forum, or from Morgan's book.

A simple 12AU7 line stage preamp is a good learning project--try a few different configurations like grid choke versus leak resistor, anode choke versus resistor load, current source or not. This will give you a good sense of the various options and tune your ears to what is available. Then try one of the more exotic pre-amps from this forum.

Then go to building the expensive output stage. Basically spend as much as you can afford on iron.

As for speakers--full range high efficiency is a great option. Fostex are cheap and middle class. Lowthers are fantastic for most people, but a lot more expensive. Other horn systems are great also.
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