Nice Kyle. Your wife will love it? Now there is a good wife.
I need two boards when you have them.
Don't know about the hum.

Yeah I'm adding Bluetooth to the receiver and it'll be her daily driver in the craft room!

I will end up making all 3 tube versions of the boards when the PCBs get in so plenty running around.

Hello guys
I can't believe what the 5902 tubes are going for now wish would bought more if I am going to built done if those amps
I getting ready to start drilling my steel chassis for the tubes and transformers and I laying them out this this weekend

Good Rich:
Anxious to finally see if you really do make progress this time!
Good luck.
John sent you all the parts for free already... all you have left to do is put it together... Right?

There are a few people on here that stocked up so I doubt it'll be much trouble to find a set of 4 from someone.

It'll be interesting to compare the 6V6, 6AQ5, and 5902 versions to each other.

Kind of want to make a 5902 single ended headphone amp.

I did.
I have a 5902 amp as the 1st one I built.. and it is just fantastic. (~ 2-3watts)

Then just for fun I beefed up the power supply and built it again as 6V6/6aq5 amp... and I can use either tubes from time to time.
( I even added a 6v/12v switch so I can use 12V6 or 12AQ5 )
This 6V6amp is everything the 5902 amp is.. in spades... Wow.

Both have enough power to fill my living room and the whole house!

6AQ5 is the 7 pin version of 6V6 so it's sounding quite terrific too.
This 6V6 version amp has more wattage than the 5902 so it can really drive my speakers nicely too. (approx 6-8 watts)

The output tube PP balance is so perfect that you get amazing stereo separation and it makes you feel like you are sitting in the middle of a concert hall.

It's also silent as black velvet between songs... not even a hint of any hum anywhere.

Hello Kyle
See I want to start making custom mini amps forsale using 5902 tubes
But the prices are starting get little crazy

Rich:
If I were you.. I'd just build the 1st amp .. see how that goes.
... then think about the rest.
I recently bought a bunch of 5902 tubes as did others here, for practically nothing. ... So we all have some to sell plus I'm sure there's more surplus ones out there somewhere too.

Those of you who have built an amp with 5902 tubes, what are you are you using for speakers?
I am interested in building one of these amps (or perhaps the 6v6 version), but it seems the 5902 tubes don't have much in the way of output power.

The 5902 amp produces approx 3 watts per channel. But it can handle quite a lot.

...because with my 5902 amp I am driving two sets of (8 ohm) 3-way speakers in parallel (4 ohms)

Fischer 3-way Bookshelf w/6" woofers
in parallel with
Auvio 3-way Bookshelf w/8" woofers.

..[for 4 ohms I use the Edcor output transformer for 4 ohms as referenced on the schematic]

That's 6 speakers per channel. No problem!

The 6v6/6AQ5 does have more power, but let me tell you ...that 5902 will blast me out of the house!

I'll second that Peter. Both those amps are exceptional. And both have plenty of power for up to 8" 3 way systems. The 6V6 probably does have move power available. I can drive a pair of Genesis 8" floor model's from the 60's with amazing sound. The 5902 should not cost more that a set of 6V6's, I guess.
I have 3 5902's that I don't need

Thanks for the info, it sounds like the 5902 will be enough for my intended use, which is a small set of speakers on my desktop. It seems that the supply of cheap good 5902 tubes has dried up, but I bought a lot of subminiature tubes that supposedly has 8 5902 tubes in it (they are unmarked), so I hope the description is right and they are good tubes. I don't have a tube tester to check the tubes, but I will see what I can do when they arrive.

I hear that the 5902 tubes were built with Mil specs. So they should be Ford tough. Build that 5902. I use Edcor OT's and really admire the performance.
You will be impressed

I bought a whole bunch recently plus I had a bunch.
So if anyone needs them let me know I let them go for a good deal + postage.

5902 tubes were designed to be used in missiles.
They can withstand 450gs while operating.

That well passes my limitations.

Made a bit of progress today. Got the sockets laid out in a way that any of the 3 compatible tube types can be installed. Meets IPC-2221B specification for clearances at 350V B+ for the 6V6. The 5902 layout will need the tube directly soldered. Not sure if this will pose a problem eventually as the tubes need replaced but it is difficult to get sockets of any kind reliably enough to warrant setting up the layout for it.

I decided to go with mono boards because the thing turns into a mess when it comes to the shared reference between the opamps, the heaters, and it gives better mounting options. The 8.5" long board that having the 6V6Gs requires looked bad and reduces enclosure options. Trying to make it as universal as possible for caps and such so people can use whatever they want.

Tubes stick out of the board opposite to the components. This is very early in laying this out but I should be able to get these out to a manufacturer by the end of the week so when I get home from Brazil(where I currently am) I can get parts laid out and solder these rather quickly when they arrive.



If there is anything you don't like about the early layout or anything you want to make sure it has let me know.

I know the 5902 socket is a bit off center, I noticed that when I took a screenshot. I haven't added the silkscreen keys yet for tube/socket orientation. I do plan on grounding pin 1 of the octals for metal types.

That's great Kyle.
If all connects are checked out accurate.. wonderful.
The 5902 leads are flexible wires so no problem there.

Guys
How important is the IC gain pot, 20k? I have built several amps using this gain adjustment control. It don't seem to make any difference when I try to calibrate. Just wondering if we could do with out it.
I like it Kyle. Mine will use the 6V6G Coke Bottles. I must have a few sets. Thank You.

That feedback pot adjusts the opamp gain from ~83:1 to 100:1. Not a huge change but enough to bring a channel in line if the amp is unbalanced. If all of your tubes are new or equally used I doubt you'd need to change it.