easy/cheap 1st tube build?

[lightningfingers]

i know this has been asked before but im going to ask it again.]i never built a tube project before, can anyone recommend a good starting point?

[petemoore]

Yes I'm Pete, but let me be Frank !!!
 I too would like a Cheap Tube Amp.
 I have Cheep Tube Amps.
 I get them from old:
 8$ RCA Victor console stereo...no later then the 60's model I guess...worked, a added 40$ worth of output tubes, next to a Fender Deluxe, [Same output tubes as^] it sounds remarkably similar, just as usable as a Deluxe -reverb, and an 'extra tone control.
 HEATHKIT...this one was 75$, and still needs work, if I ever find a better deal on the tone tubes [70$ A PIECE..OUCH], this amp would be absolutey Killer, like the...
 DYNAKIT ST70...Dad built. I rebuilt the whole front end, point to point, bypassing the baked PCB around the 7199 tube sockets, re-biased the whole circuit in a very complex way...Dropping the AC voltage supply would have been the way to get it 'back to 'specs'...at the time voltage coming out of a wall socket would be between 90v-110v, not 120v like these days...enough to upset the whole bias arrangement.
 Teeny tuber Radios, free, amazing what less than 2w can do.
 Powered extension cabs from the very early Mono or Stereo reproduction days.
 Basically you can find old keyboard amps and speakers in old keyboards units that fail...the amp and speaker might be just fine, are most probably workable or fixable...
 Look for old junk with tubes in it. There are your 'cheep transformers, frame etc etc etc etc. ... you can build using them, I recommend retrofitting, and rebuilding on the existing units, rehousing them etc.
 So you Can actually get a tube amp for cheap.
 Also look for ones that are for sale that have problems...pick it up dirt cheep, and fix the problem..there you go!!!
 However there is something to be said for New Amp...alot of things..new caps, pots, jacks etc etc etc etc.... etc.
 Drag is, New Tube amps are $$$, and probably worth it, I like my old retro tube jobs Real Good soundwise. Really great.
 They are out there, it is your duty to save them from the landfill, should you choose to accept it.
  You might want to change your handle before you start getting your fingers around high voltages though...lol
 By scouring for deals on used Tube stuff, you can get the whole shooting match pretty cheap, already running, or close to it.

[Arn C.]

Petemoore writes:  

HEATHKIT...this one was 75$, and still needs work, if I ever find a better deal on the tone tubes [70$ A PIECE..OUCH],

What tube are you looking for?  Maybe I can help you!

Peace!
Arn C.

[Paul Marossy]

How much power do you want?

The Firefly is an easy build. (1 watt?)
The Octal Fatness isn't too bad. (5-10 watts)
Fender Champ
Fender Bassman
Marshall Plexi (18 watts)
Matchless Spitfire (15 watts)
Several of the projects at www.AX84.com

I consider the ones above to be fairly easy to build - no reverb, no vibrato, simple tone controls (if any are present).

The higher wattage amps aren't necessarily more difficult, but there is more stuff - 4 power tubes instead of 2, etc. It just gets more complicated from there. Look at a Fender Twin Reverb schematic sometime. Not an easy build!

No tube amp is really cheap to build, though. My Firefly cost me about $200, even using stuff I had lying around. My Matchless Spitfire clone has cost me about $350 so far, and it will probably take another $100 to finish it. I'm just waiting for the parts now.

Tube amps parts are in a whole different category as far as price is concerned. Maybe you can get salvaged parts and save some money, but it's a lot harder trying to round up stuff that way than it is to just buy it new, off the shelf from a supplier.

[MartyB]

Try Fred Nachbauer's project.  It's a 12a_7 single tube preamp.  It cannibalizes two readily-available wall warts which are easy to find in junk stores.  I've made two of them and housed them in old A/B steel switchboxes.  They sound great.  His site has some sound samples.  If you don't want to wire point-to-point there's a pcb layout available at Tonepad.

http://www.dogstar.dantimax.dk/tubestuf/mctube.htm

MartyB

[Paul Marossy]

IF you want a tube based stompbox, you could try the Shaka Tube. That's a cool one, which I built, of course.  :wink:

[MattAnonymous]

If you're looking for something really simple, but tube based I'd go with the ruby tuby preamp.  I'll be building one soon for my Peavey Deuce.

[cove]

what kind of output wattage does the ruby tuby preamp have...nice that it runs off of 12v.

[MattAnonymous]

dunno, but from what I understand preamps are measured in dB .  Not a lot of info from what I've seen, but definately a simple, small design.

[bobbletrox]

If you're looking for something really simple, but tube based I'd go with the ruby tuby preamp.  I'll be building one soon for my Peavey Deuce.

Post a build report when you finish!

[petemoore]

Looking tube schematic I've ever seen !!!
While I'm looking, ...help me get this straight?
 Jfets could actually just about go in there? Ie the schematic certainly looks similar [nearly identical in many ways] to a transistor schematic.
 Questions [is there a schematic with expanded text and explanations of pin names?...I guess tubes have different pinouts too...this is as good as any I've seen, to use as The first example for reference.
 1.    pins 4 and 5 are for the heater?
 2.    what are the names for the tube parts that connece to pins 1,  2,  and 3?... pins 6,7 and 8 could be called by the same names as 1, 2 and 3 [which one is A Cathode, which one is An Anode, and which one is A Plate?]  
 I'm starting to get a kick out this schematic...the 250k looks like it's in a trimpot position...[would be rather large for a collector resistor]...hm..works like a gain knob.[?]
 I just happen to be having 12AX7"'s and sockets, a frame, there's even a transformer in there, now a Whole lot else tho...Talkin' bout a Dyna tube preamp.
 Yupp, I feel like I'm about to try a tube build.
 and...if more voltage were provided at the supply side, would this circuit work as shown?
  ..yepp, Really good to see tube posts!!!

[lovekraft0]

Here ya go, Pete:

Pins 1 & 6 are anode or plate leads, pins 2 & 7 are grids and pins 3 & 8 are the cathode leads. Pins 4 & 5 are the 12.6 volt heater leads and pin 9 center taps the heater filament so you can run it in parallel at 6.3 volts. Biasing is very similar to a FET, although it's not nearly as linear. I haven't built the Ruby Tuby, but it's very similar to a Fender Tweed preamp with a lot more available gain. The gain control also adjusts the operating point of the triode, so I suspect there's some asymmetrical clipping going on there to sweeten things up. Check out RG's Tube Amp FAQ for more specific info. HTH