Spud: what, again!?!

[MellowTone]

Originally Posted by tubelab.com

Any way you lay it out a dual socket board will be bigger, increasing the cost. I haven't looked into it, but dual socket designs are usually best done with the common parts in between and the sockets on the edge of the board.

Originally Posted by squiffiness

The pin sizes are known (.050" and .040"), but it sure sounds like the sockets that are PC mount will vary to the point where you'll need to know the source and bought some to confirm the PCB pad circle diameter for your socket.

Hmm. After looking around for 6LU8 and 6LR8 tubes a bit more, they seem fairly comparable, so at least cost wise this is probably a moot point anyway.

That said, has anyone had any luck finding PCB mount Novar sockets? PCB mount 12 pin Compactron sockets are easy to find, and Magnoval too, but not Novar (only place I could find with Novar PCB mount sockets was charging $10 a pop)
Unless we wanted to go the route of manually crimping each pin in a Magnoval socket, we would need to find a decent supply of Novar sockets before putting this all together. Plus, as mentioned by squiffiness, as they don't seem to be in current production as far as I can tell, we'd probably need them before sending off the board to make sure the PCB holes for the socket are correct.

Was there a specific reason for going with the 6LR8 over the 6LU8? As far as I understand at, they're identical apart from the base, so it would seem as though going for the 6LU8 might simplify things?

EDIT: Just realised George explained the reasoning for choosing the 6LR8 back in post #5. It's quite late and I think my brain's checked out for the day

[tubelab.com]

That said, has anyone had any luck finding PCB mount Novar sockets?

Stan at ESRC has them. I saw him today at the hamfest, the sockets are there at his display, I had them in my hand. NO, I wasn't smart enough to ask the price, or measure the pin circle. This was the third day of standing in a huge asphalt parking lot in the 88 degree weather selling my warehouse junk. One more day to go. My brain was somewhat fried from the heat, 12 hour days, and lack of sleep and decent food.

I have however succeeded in converting one cubic Honda Element full of "stuff" into a bundle of cash. I will be stopping at ESRC next Saturday on my way home to drop off some tubes, and pick up some tubes.....and some Novar sockets.

I will check again for price and availiability of 6LU8 VS 6LR8. Availability is the main criteria. No point in designing an amp for a tube you can't get.

I am on hotel internet now. I probably won't be back to this forum until Monday evening. Any questions for Stan......post them here.

[rknize]

So what's the word? I'm probably going to build a spud-like amp for my computer desk. I'd probably prefer the spud over one of Pete's compactron amps, because George is funnier (sorry Pete .

[vinylkid58]

Originally Posted by tubelab.com

This was the third day of standing in a huge asphalt parking lot in the 88 degree weather selling my warehouse junk. One more day to go. My brain was somewhat fried from the heat, 12 hour days, and lack of sleep and decent food.

I'd be toast after the first day.

Originally Posted by rknize

I'd probably prefer the spud over one of Pete's compactron amps, because George is funnier (sorry Pete .

Even the stock DCPP amp has too much power for the desktop, but it does sound good.

jeff

[rknize]

Originally Posted by vinylkid58

Even the stock DCPP amp has too much power for the desktop, but it does sound good.

I was referring to his "Jonokuchi" (dual triode) and his "Mighty Midget" (dual pentode).

[squiffiness]

Originally Posted by rknize

I was referring to his "Jonokuchi" (dual triode) and his "Mighty Midget" (dual pentode).

The Midget appears to be a more involved design to stuff into a custom FrontPanel Express case unless you mod it somewhat.

The SimpleSpud (hoping...hoping) is much simpler in design from what I can see.

Earlier in the thread, George alluded to having something like a bunch of parts kits and gain matched tubes for the small board, but had not optimized his PCB design. Hopefully, the earlier post about small batch, inexpensive board houses in The Land of Mao will push this project over the top.

Another design (see neurochrome.com) used the functional twin of the 6LR8; the compactron 6LU8. The end product uses a 5AR4 in the P/S, a toroidal power transformer, UL and CFB and is a real looker in its wooden home.

It does look like George confirmed Novar PC mount socket availability, but wanted to confirm tube supply.

In the meantime, I have some time to burn, so I will keep trying to launch my own. If George beats me, I'll buy his board since he actually knows what he's doing.

[tubelab.com]

It does look like George confirmed Novar PC mount socket availability, but wanted to confirm tube supply.

My current plans are now to leave for Fort Lauderdale tomorrow morning. Drive the 1200 miles home over two days. Unload all the remaining hamfest stuff, load the trailer up with tubes and my old radio collection, turn around and drive 200+ miles back to Orlando to for an antique radio show Saturday morning. It happens to be in ESRC's parking lot, so I'll have some time to talk to Stan and maybe look around the warehouse. At last count it contained about 3 million tubes.

[MellowTone]

Originally Posted by tubelab.com

I have however succeeded in converting one cubic Honda Element full of "stuff" into a bundle of cash. I will be stopping at ESRC next Saturday on my way home to drop off some tubes, and pick up some tubes.....and some Novar sockets.

I will check again for price and availiability of 6LU8 VS 6LR8. Availability is the main criteria. No point in designing an amp for a tube you can't get.

I would be willing to take a stab and say that bundle of cash is of a lot more use than a cubic Honda Element of tubes

Had a bit of a look around, and found vacuumtubes.net has 21LR8 tubes for US$0.75 each. Anyone have any experience with them? Although I'd need another heater tap on the PT, not a particularly expensive addition and it broadens the supply of *LR8 tubes I can use.
Also, were there any other voltage variants of the 6LR8 available? I've only been able to find the above two thus far.

Originally Posted by tubelab.com

It happens to be in ESRC's parking lot, so I'll have some time to talk to Stan and maybe look around the warehouse. At last count it contained about 3 million tubes.

If we can confirm pin circle, price and stock levels of those Novar PCB mount sockets would be handy. Assuming the PCB goes ahead, even if you don't do a full parts kit (a much bigger investment of both time and money) would you be willing to buy and ship the sockets with the board? Seeing as how scarce they are, and for those of us outside the US, would save some extra postage and running around.

[tubelab.com]

I would be willing to take a stab and say that bundle of cash is of a lot more use than a cubic Honda Element of tubes

I didn't sell as many tubes as I had thought I would. After I finally got a chance to go shopping I found someone selling NOS tubes for $0.25 each! He had a crowd. Yeah, I bought a few.

I sold "stuff" from my warehouse, old stereos (including a Fisher 400), test equipment, tube testers, transformers, and all sorts of stuff I didn't use.

Also, were there any other voltage variants of the 6LR8 available?

I know there was a 21LR8 and a 31LR8. Not sure if there was a 16LR8.

Assuming the PCB goes ahead, even if you don't do a full parts kit (a much bigger investment of both time and money) would you be willing to buy and ship the sockets with the board

I already have all the parts for building the PC board itself. I was planning to do a "small parts kit" like I currently have for the Simple P-P. It contains all of the parts that you solder into the board. No tubes or transformers. I have about 100 of the 6LR8's too. I even tested them and sorted them by power output for a fixed input voltage to assure evenly matched channels.

I sold some tubes to Stan at the hamfest. He owes me some money, so i will pick up a bunch of sockets Saturday.

My current plans are now to leave for Fort Lauderdale tomorrow morning.

Currently in a hotel room about halfway home.

[squiffiness]

I have noted in the schematic for the Simple ProtoSpud ultralinear mode is used by not CFB like in the SSE.

Was there some design reason for avoiding CFB with the 6LR8?

A couple of other amps out there in DIY'land use various forms of feedback. The power hungry spudders all use UL for boost and some CFB for THD.

Could/Should the ProtoSpud Mark II consider CFB as part of the equation since a feedback cap would replace the bypass cap to ground on the pentode?

Second, since the first ProtoSpud underwent some cathode bias surgery on the triode section ("yellow" diode in for cap/resistor combo), will the design go traditional Cap/Res or move forward with the yellow diode to get the voltage drop consistent?

Continue to hope ProtoSpud will come to life as a PCB some time in the future.