Newbie Tube Pre-amp Build

I've been thinking about this since we built the CarverFest Amplifiers. Although my soldering skills are marginal, I figured since this little pre has so few parts I could manage the construction and manage installing some upgraded parts in the process.

This is the link:

http://diyparadise.com/web/images/stories/ANM7.gif
or
http://diyparadise.com/web/images/stories/yeo5687.gif

This should take you to the schematic I want to use. Now, what I want to do is pray upon those way more knowledgeable than I am to look at this and make some mod/upgrade suggestions, keeping in mind this pre is going to be running my CF amps and the Klipsch speakers.

Here is what I have in mind so far.

In the power supply I want to use a Jensen 47+47uf 500v Cap. Is that close enough to the 50+50uf 500v to work alright or do I need to stick with the JJ can? Next are the 470uf caps that are paralleled with the 470 ohm resistors. Are Muse Caps OK and Mills resistors good here or is there something better? I had planned on Jensen .47uf Caps on the outputs with AN Tantalum resistors all through the signal side. A Goldpoint stepped attenuator and selector switch. The power transformer I planned to get from Edcor and Hammond chokes from Digi-key. I 'finally found covers(thanks James!!!) I found a chassis with a bottom cover that are painted satin black and some tube protectors.

I'm open to ideas from y'all with tube experience. Please don't be bashful:-)
Thanks for giving me a hand!!

ray

Take a look at these kits.

http://www.tubes4hifi.com/home.html

Cool stuff, but I think I want to build at least 1 small pre. Maybe for my office system. Like the models with tone controls though.

Been digging the Audio Note kits also. Way Kool!!!

ray

For those interesting in the idea of building their own tube preamp, here is a video with some good basic info.

http://www.youtube.com/watch?v=mrMGGHp8yLk&feature=youtu.be

This is not a detailed parts value design guide. Just a what it is and what it's purpose is. This is meant to be an ongoing series with more info coming. Roger Modjeski is one of the tube gods if you don't know of him.

Another thought is if you want to start a tube preamp project and help to keep it kind of simple, here is a way to do a power supply in a simple and reasonably decent way. Use this HV DC output supply....

http://www.mpja.com/prodinfo.asp?number=8530+PS

This is an adjustable supply that will get you up to about 270vdc. Not hard to get a preamp that uses that or lower for B+. That brick and a filament transformer and you have your voltage supplies.

You start to lose the simplicity, but putting those two things in a seperate box and you've got a PS that could be reused if you redesign. Preamps are good to have in seperate chassis if you don't mind the extra work. If going with one chassis, just use space to your advantage and don't crowd things.

OK....two project thought starters. Who's going first???? Great winter project!

Mark

OK....two project thought starters. Who's going first???? Great winter project!

Mark

I have ordered all of the parts for my build(most have already arrived).....except the chassis. I'm planning on roughing it together and getting it to work, then figuring out how much space I really need and then ordering the chassis. I've bought 2 sets of parts. 1 build will be on the cheap while the other will have some boutique parts. I've got some Mills and AN resistors, Jenzen, Relcap, and Auricap caps in the signal side(to see what this deaf guy can really hear) and I found some gawd awfully expensive BlackGate and Jenzen caps for the power side. I'm going to try using both sides of 2 5687s in the pre to get back the 20db I'll lose inserting the passive tone controls.

ray

Here is an example of using that $50 adjustable PS brick in a power supply for a preamp.

Front with seperate Filament and B+ switching


Rear side with IEC, fusing, PS output connector and metering test points


Interior with adjustable HV B+ supply and regulated DC filament side


DC filaments is a level that isn't absolutely required and as you can see adds complexity and space requirement. Something to consider carefully is when adding things for higher quality or taking on not absolutely required features, is that it can really add to the effort you have to go to. Drilling mounting screw holes, wiring things in, buying materials. Figuring out mounting and spacing. And so on....

It's easy to be think high going in. But harder to bring to the finish line. Balance desire versus actual needs versus performance.

Mark

Good fun and great reading.

Keep updating this --please!

Roger Modjeski has posted the second in his intended series on building with tubes. This one focuses on the tube itself.

http://www.youtube.com/watch?v=z46PInHdmXI

Basics are important!

Mark

Roger Modjeski has posted the second in his intended series on building with tubes. This one focuses on the tube itself.

http://www.youtube.com/watch?v=z46PInHdmXI

Basics are important!

Mark

When I have time I've been reading from this link.

tscm.com/NEETS-v06-Tubes.pdf

ray

I've been reading here for those of you browser delayed

http://diyaudioprojects.com/Solid/12AU7 ... dule-6.pdf

ray

I am ready to begin my pre build. All of the parts(except tubes) are finally here. I'll be posting pics of the parts later today. On another front I've been in contact with one of the DarkStar engineers. I have a copy of the logo and some supplemental information including some specifics of cabinet design and performance level. It has strong similarities to Sunfire subs.

I'm going to be laying the pre out and figuring where each part is going to belong in the chassis. Pics should follow each step along the way. Constructive criticism VERY WELCOMED!!!

ray

you can do it.......you can do it all night long.....go RAY!!!!!

Ok...Feeling like what I'm throwing in is again not exactly right to be in Ray's thread here. But we don't have much of a DIY or tube build area.

But if you missed out on the CF tube amp build, you're not sure where to start with doing anything with tubes, then here may be an option for you. This is part of the on going series that I've mentioned above.

Roger Modjeski is now working on putting out a small tube amp breadboard amp project. Looks like you'll have to join his forum right now to get access, but it could be an avenue to getting started for some.

Youtube video here...
http://www.youtube.com/watch?v=7qg9ot20EdA

Thread here...
http://www.audiocircle.com/index.php?topic=113764.0

The forum link is...
http://www.audiocircle.com/index.php?board=124.0

Mark

Ok...Feeling like what I'm throwing in is again not exactly right to be in Ray's thread here. But we don't have much of a DIY or tube build area. Mark

James, can we(you) build a DIY tubes and SS section on the Forum? Mark, Jesse and some other have possess a large knowledge base that I'd like to take advantage of and I'm sure other would also.

Thanks!!

ray

here's a link to pics of my parts layout for the M&M 5687 pre build.

http://www.flickr.com/photos/fotosnap/

I haven't had time to even start working on the build yet , work has intruded as usual. I bought a Lightstar Direct pre chassis from one of Bob's engineers to use for my build. $50 shipped, and it's way cheaper than anything else I'd found.

ray