Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jojokeo on March 08, 2011, 08:24:56 pm
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Just sharing a fun little weekend project. I've had a very small little PT for a long time and so I came up w/ small bedroom practice amp for it called Tiny Giant. My first using the jsch & psu programs too. It was drilled & primed starting Friday afternoon, painted Saturday morning, and wired up & playing on Sunday. It's all of 1.1watts according to the mighty 6AK6 "power" tube data sheet. :laugh: It actually sounds pretty darn good for such a little guy that can even get musical feedback going. Joe
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Nice looking amp! I need one of those for my daughter.
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I like it!
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:grin: NICE :grin:
Can you post schematics and values ?
Thanks
Kagliostro
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I haven't done that in a long time but I think it's so much fun, kind of like taking a vacation for an amper. Just have a pile of parts and a concept and just drop everything and go for it. Very neat job for such fast work? Platefire
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Did you use that Rust-O-Leum hammertone paint?
I really like that stuff, very hard when cured for a month or so.
That build has a real vintage look all round, looks like a project right out of those 50's electronics magazines!
What kind of speaker are you pushing it into?
Will you be using a cover for the bottom? or putting it into a cab?
Ray
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That's a little beauty! :grin:
I've never played a simple, two pentode amp but there is something special about those really stripped down circuits. Gain, Tone, Volume = SWEET! Nice, clean build too.
Can you post schematics and values ?
It's in the very first link of jojo's first post - the "Tiny Giant.jsch" file. You'll need to download the JSchem program to open the file (if you haven't downloaded it already). Go to the schematics section here for the download.
Cheers,
Chip
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very nice work. love the chassis and p2p work.
i have thought of experimentation with a similar tube, the 6AS5 for a while.
http://tubedata.milbert.com/sheets/093/6/6AS5.pdf
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Really cool. Thanks for posting the pics and schem!
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Thanks for the nice words everyone. I haven't shared a whole lot as far as personal builds as everything I've done has been schems and layouts drawn by hand plus I'm not sure that I've done anything special deserving of posting really like tubenit/geezer have. Just the usual kind of things w/ my own takes and combinations of ideas sort of things (you all know what I mean).
I had some fun making my own components in the jsch program once I got the hang of it and if people haven't noticed, I made a layout page if you look down at the lower tabs. The power switch doubles as a standby switch if you want to use it that way, the gain switch on the pentode is a must have whenever I use a preamp pentode these days (really makes them versitile IMHO), and I like to include the tone lift when there's nothing following the pentode in case you want full drive signal into the power tube. I only had to change one component - the coupling cap lowered from a .01 to a .005 to clean up a little muddiness and that was it as far as fine tuning.
The layout page would be easy for first-timers to follow it if they wanted to make such an amp very easily by following it. I really like the jsch program now that I've got the hang of it. It's a very handy program to have and use.
The amp is still loud enough for the wife to close all the doors or still tell me to turn it down when her quality TV time is being interrupted :laugh: (where's the evil laughing icon?) >:)
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Did you use that Rust-O-Leum hammertone paint?
I really like that stuff, very hard when cured for a month or so.
That build has a real vintage look all round, looks like a project right out of those 50's electronics magazines!
What kind of speaker are you pushing it into?
Will you be using a cover for the bottom? or putting it into a cab?
Ray
You got it Ray, it hides imperfections nicely and gives a cool look plus it doesn't run easily. I have a few speaker cabs on a footswitch that goes btwn a Celestion greenback & a Weber 12A125-A. at the moment. I don't worry about the bottoms of my chassis' being covered as I like to peer into them to check values on occasion or maybe make a quick change sometimes to. Since I have about 4 various chassis-type amps done now of the same size (but different circuits) I may have to get my table saw back into action for making small cabs for them yes? As much as I like woodworking, covering, etc... I'd rather be playing and building though. So maybe doing a run of them it would be quicker to bang out a bunch at the same time and not be so time consuming?
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Sorry -- I must have missed where the schematic was located. Can you help? thx.
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it is a link in the starting post.
attached a GIF.
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Oh there *are* three links -- whadda dunce :embarrassed: thx.
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very nice work. love the chassis and p2p work.
i have thought of experimentation with a similar tube, the 6AS5 for a while.
http://tubedata.milbert.com/sheets/093/6/6AS5.pdf
Here's another one I was wanting to use but my "little red caboose of a PT" wasn't rated to handle it...
http://tubedata.milbert.com/sheets/127/6/6AN5.pdf
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very nice work. love the chassis and p2p work.
i have thought of experimentation with a similar tube, the 6AS5 for a while.
http://tubedata.milbert.com/sheets/093/6/6AS5.pdf
Here's another one I was wanting to use but my "little red caboose of a PT" wasn't rated to handle it...
http://tubedata.milbert.com/sheets/127/6/6AN5.pdf
kind of sorta, maybe like the 6CA5 - another high slope low watt tube.
http://tubedata.milbert.com/sheets/093/6/6CA5.pdf
lots of fun to be had with all these obscure little tubes.
good thing there still a bunch of them around and that they are still relatively inexpensive... :grin:
i do like the 6BK5 as well.
excerpt below from a guitar amp manual...
We used 6BK5s because (a) they're deviant, (b) nobody wants them, and (c) they KICK ASS on the
junky tubes most guitar amps use. 6BK5s would also make great high-fidelity power tubes, thanks to
very low distortion and great peak-power capability. But instead, we had to put them in an absolutely
hideous guitar amp. Yes, we suck.
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Those look to be workable definately. I've already made another one similar to this but w/ a 12ax7 called Little Giant that uses an EL95/6DL5 that rips it from 3 - 4.5 watts. It can also sub for a 6AR5 or a 6AQ5/EL90. There's a little bit of power difference from the 95 to the 90 but not a whole lot by the ear.
As for any of the tubes we've mentioned - they're all too much for my little PT at only 125v @ 15mA w/ 6.3v @ .6A total. So I'm already pushing it w/ the 6AK5/6AK6 combo. I can't imagine I'll ever go lower in output power but this was fun to experiment with and use that tranny after looking at it for years on a shelf. I was always thinking I'd use it for adding a 12ax7 or two in an existing amp at some point.
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...uses an EL95/6DL5
buttery used to thrash a little grundig tape deck he rigged into a guitar amp that used those and an EF86 front end... IIRC he said it was sounding better than it ever had and then it caught on fire.
:angel
...use that tranny after looking at it for years on a shelf.
it is good doings to recycle vintage stuff. :smiley:
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I loved that amp! OK tape recorder. 3 nights before a SXSW showcase, it burst into flames, but not before shocking the p155 outta me. Dying amp + guitar + person + microphone = loop to ground. I got my paws on another one. Gutted it down to just the amp circuit bit it wasn't the same so I sold it. I have a theory that the rumbling 1950's motor contributed to it's tone. It was a 1 trick pony but I've never gotten that tone from another amp. The death of that amp was a big contributing factor for me getting into thermionics.
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jojo, here's a list of tubes i feel may be of interest to our amp building community. please amend it if you wish.
i cannot post xlsx files, please send me a message if any of you wish to have the spreadsheet.
a note about the gm column; if the Va max < 250V then it's usually measured at Va max, otherwise, it is usually measured at 250V.
--DL
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i cannot post xlsx files
You can if you will first change the filename extension to one that the board will accept. Just mention that in the message body. Oh, and it still has to be less than the max filesize limit.
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...uses an EL95/6DL5
buttery used to thrash a little grundig tape deck he rigged into a guitar amp that used those and an EF86 front end... IIRC he said it was sounding better than it ever had and then it caught on fire.
:angel
Now that sounds very metal indeed!!! :guitar1
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Quote from: kagliostro on March 09, 2011, 07:07:41 am
Can you post schematics and values ?
It's in the very first link of jojo's first post - the "Tiny Giant.jsch" file. You'll need to download the JSchem program to open the file (if you haven't downloaded it already). Go to the schematics section here for the download.
Sorry for the inattention thanks for the warning
Kagliostro