• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Amazing $50 3 Tube Preamp

You can get a fuse assy. from rat shack. Iec with fuse is alot easier to use.( less wires) If you look at my amp in my link.(some where in this thread) You will see the fuse holder switch and iec plug.

Mark
 
Last edited:
THE IEC/fuse is the way to go. I already had a Rat Shack fuse holder and a scavenged power cord and didn't want to order anything. Plus I'm cheap. :D
 
Got home and fired it up, it definitely is warmer sounding but I'm not sure what I'm hearing yet. It does have somewhat of a hum though thus far. I haven't installed it in anything yet, so I have some working to do.
 
I've finally received all the parts needed for my hybrid integrated amp that I spoke of earlier in the thread. Yesterday after work, I threw it all together for a test listen. The chassis/tray is the bottom portion of a Philips DVD player that I gutted. I retrofitted some speaker terminals, inputs, and power receptacle.

I plan to make a front bezel out of wood and then mount a power switch and the volume pot in the front bezel. Then I'll cut a hole in the cover panel for the tube to stick through, and mount the 12vac transformer and the huge capacitor on top a la "retro DIY tube amp" style. Mods to the Tripath amp board include 1) replaced input electrolytic coupling caps with bipolar PIO Roedersteins, 2) removed unnecessary connectors to make room for direct soldering, and 3) (obvious) removed the stock 3300uF power cap and tied in the huge 9500uF sucker!

It sounds un-f&*$ing-believable! Way better than it has any right to sound, that is for sure. I have maybe $60 into this thing (I had a lot of the parts laying around) and it rivals the massive tube amp it is sitting on, all the while using a tiny fraction of the power of the tube amp!

I can't believe it.

Hybrid_Amp_Test.jpg
 
Last edited:
Hey that looks great. I bet that t-amp is freaking out with that biga$$ cap. I might try this setup with the tk2050 amp I have.

Mark
 
opa1 said:
Hey that looks great. I bet that t-amp is freaking out with that biga$$ cap. I might try this setup with the tk2050 amp I have.

Mark
Click to expand...

Thanks!

I plan to make it look much better and optimize the wiring. At least now I know it sounds great!

I'll post back here when I have a "finished product".
 
Love it!

Amazing the good sounding stuff you can get from China for peanuts.

Can you lay that big Mallory on it's side? Hows the range on the preamp volume pot?
 
The look I have in mind includes the Mallory standing on top with the power transformer, and the tube sticking through a hole in the top.

Perhaps hard to imagine, not not unlike many classic tube amps...

Oh, the volume pot ... Ummm... It goes from "off" to "louder than I need". That's about as specific as I can be, as I never paid much attention to volume pots unless they are scratchy as hell.
 
I just bought the 3 tube magic buffer thingy and will build my own integrated with it and a 2x50 sure board. but for now I have to wait for it to make the journey from China.
 
Nice work Cogitech.

My 3 tube pre arrived as well and is sitting on my bench waiting for me to be done with my 2A3 SET amp build. Any ideas of how to mount the pre so it looks presentable in a living room? Maybe separate boxes for the pre and the TA2020?
 
goldleaf said:
Nice work Cogitech.

My 3 tube pre arrived as well and is sitting on my bench waiting for me to be done with my 2A3 SET amp build. Any ideas of how to mount the pre so it looks presentable in a living room? Maybe separate boxes for the pre and the TA2020?
Click to expand...

There are so many enclosure options for the pre. I'd like to see one mounted in a nice wooden cigar or tissue box. The craft stores like Hobby Lobby have all sorts of nice wood boxes. Some are deep enough to hold the pre and cover with a piece of plexi from Lowes ( they will cut to fit ). The pre makes little heat and the plexi can easily be vented. Since it uses the Matisse circuit it could be called a "Matisse under glass".

If you have shelf space, separates allow more flexibility when swapping gear. I recently tried my 2050 with a Bottlehead preamp which was easy as I built it as a power amp.
 
I received my 3 tube pre yesterday, it arrived well packed in a box wrapped with lots of tape. I think there is a post on wiring the transformer here somewhere. I need to come up with a few things then I am going to build a copy of the amps posted here using my Sure board 7492 chipset. I am not sure what I will use to house this and am thinking about more than one set of inputs. stay tuned..
 
Mine's been in limbo. My chassis plans turned out to be more work than I care to devote to it. Back to brainstorming. Need something simple like Poultry did...
 
68custom said:
I received my 3 tube pre yesterday, it arrived well packed in a box wrapped with lots of tape. I think there is a post on wiring the transformer here somewhere. I need to come up with a few things then I am going to build a copy of the amps posted here using my Sure board 7492 chipset. I am not sure what I will use to house this and am thinking about more than one set of inputs. stay tuned..
Click to expand...

The wiring diagram is a few pages back. Using a good switch box for multiple sources is a heck of a lot easier than building in extra inputs. I use one made by Niles.
 
Had to do it. Order placed last night. 3 Tube just like you said . Already want new caps and tubes to play with and don't even have it yet ! Gotta find a wood box too. Yard sales and flea market bound ! Thanks for this very interesting post ! I would like to know more about the voltages as I have many power supply's around and would like to know advantages of changing the stock one. I would think that using the same voltage but higher amperage is what you are shooting for ? Cleaner power ? Thanks !! with best regards, vsat88.
 
vsat88 said:
Had to do it. Order placed last night. 3 Tube just like you said . Already want new caps and tubes to play with and don't even have it yet ! Gotta find a wood box too. Yard sales and flea market bound ! Thanks for this very interesting post ! I would like to know more about the voltages as I have many power supply's around and would like to know advantages of changing the stock one. I would think that using the same voltage but higher amperage is what you are shooting for ? Cleaner power ? Thanks !! with best regards, vsat88.
Click to expand...

Glad you're pumped. It's a cheap and cheerful little project.

I'd like to see someone build it in a wooden cigar box with holes in the top for the tubes to stick out. Actually the stock 6n3 Chinese tubes are rather tall whereas the replacement 2c51 are about half as tall and I'm guessing may fit inside a cigar box with the lid closed.
 
I may well use a Cigar box ! However what about the last part of my post Poultrygeist ? ( I would like to know advantages of changing the stock (transformer) one. I would think that using the same voltage but higher amperage is what you are shooting for ? Cleaner power ? Thanks !! with best regards, vsat88.) Please do tell ! Thanks !! Best regards !
 
vsat88 said:
I may well use a Cigar box ! However what about the last part of my post Poultrygeist ? ( I would like to know advantages of changing the stock (transformer) one. I would think that using the same voltage but higher amperage is what you are shooting for ? Cleaner power ? Thanks !! with best regards, vsat88.) Please do tell ! Thanks !! Best regards !
Click to expand...

I'd try it stock and live with it awhile before changing anything. If I ever get around to it maybe a volume pot upgrade would be in order. The stock one has a limited range.
 
You must log in or register to reply here.
Back
Top Bottom