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bamph 25th March 2010 04:08 PM

Building the Oddwatt S2 “Poddwatt”
A few months ago I started looking for a tube amplifier that would be a good first amp to build. I found the Oddwatt S2 on and thought I would give it a go. I’ve noticed that this amp hasn’t received very much buzz and I was wondering if anyone besides rparsh has built one?

The reason I want to build this amp is that it appears simple, has excellent documentation, and can be directly driven with an MP3 player. unfortunately though, because I don’t have any background experience with tube amplifiers, I have a few questions about implementing the design. Any comments or advice would be appreciated.

I see that the 47uF and 100uF caps in the power supply a rated at 350V min, but I was wondering if certain caps are preferred.

I guess a temperature rating of 105 would be good.

Does low ESR matter?

Any special considerations for the 10,000uF cap in the heater power supply?

Also, I was wondering what the purpose of the 100uF 10V cap on pin 3 of the 5751 is?


rknize 25th March 2010 06:42 PM

This should probably be in the Tubes/Valves forum so that more people see it.

urmoo 26th March 2010 11:06 AM

Hummm, if you already came to Tubelab site, why not to consider Simple SE by Tubelab? Excellent documentation, very stable and "foolproof", lot of buzz around it and the sound its able to make is remarkable.
Simple SE board

bamph 26th March 2010 09:18 PM

I thought about going with the Simple SE, but with all the options (tube type, power transformer, rectifier, choke, etc.) I didn't really know where to begin. Also, can you drive the Simple SE directly from a CD player or MP3 player, or do you need a preamp?


bamph 26th March 2010 10:18 PM

Just found this post about the Simple SE. It looks like you can drive it directly with a CD player. This quote is from the Input sensitivity for Tube Lab Simple SE thread.

George said:

The absolute sensitivity can vary quite a bit. The biggest influence is the connection of the OPT, UL is more sensitive than triode. Next is the use of CFB or not, followed by the choice of output tube. The EL34 is more sensitive than the KT88 and the 6L6GC is in between. The type of 12AT7 and the efficiency of the OPT also affect the sensitivity.

The amp is designed such that under the worst case (KT88 in triode with CFB) the amp can be driven to clipping with a CD player (about 2 V p-p) In the other extreme (EL 34 in UL without CFB) the sensitivity can be as high at .75 V p-p.

neonthecat 27th March 2010 02:21 AM

You certainly can drive the SSE directly from a CDP. I've also used mine with an FM tuner, and MP3 player. Plenty of volume.

The SSE is a wonderful project for a number of reasons, not the least of which, is the superb documentation by the designer (George). It's hard to make a mistake. The design is very versatile, allowing you to easily sample the sound of various tubes.

Depending on what parts you may already have on hand, this is an amplifier that will not bust your budget. I compare my little SSE to my Primaluna and Conrad Johnson gear, and it's not embarassed. Get a board from George and start having some fun!

mikejennens 27th March 2010 02:31 AM

If you want to got with a kit, I've heard good things about the S5 Electronics 12G amp.
S5 Electronics
There are even sites dedicated to upgrading this amp.

rknize 27th March 2010 02:47 AM

There are a lot of choices, but if your intent is to drive it with a portable, then you probably just want to set it up for the EL34. 5k primary on the OPT, etc.

blue lander 28th March 2010 01:51 AM


Originally Posted by mikje (
If you want to got with a kit, I've heard good things about the S5 Electronics 12G amp.
S5 Electronics
There are even sites dedicated to upgrading this amp.

I built a K-12G before tackling the Tubelab SE. It's dirt simple to build (they include everything, even a wooden block to mount it on) and there's some worthwhile upgrades out there on the internet for it. I'd recommend it if you want to build an amp for cheap from an easy kit. Anybody with a soldering iron can build this kit. But soundwise it's absolutely no match for the Tubelab, and doesn't even sound as good as the tube amp I got from an old console stereo. So I wouldn't recommend it if you want the best tube amp that $250 can buy.

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