Simple P-P "beta builders" thread

[tubelab.com]

There are three people of varying skill levels building Simple P-P amplifiers using parts kits that I provided, and will have available after at least one of these builds are completed. The purpose is to find errors, and I have already received feedback from two of the builders, and only one has received their kit.

As many of you know the construction manual was assembled in several places, on 3 different computers, over a 6 month period, and it isn't even finished yet. For this reason I don't have 100% confidence that everything is perfect yet. It is hard for me to catch everything since I can build these things blindfolded.

Sherri assembled the first batch of parts kits when she was here for 10 days, and one tube socket was missing from all of the kits.

I am starting this thread for the beta builders to post their findings, photos, and general thoughts on their Simple P-P amps. I ask that this thread be reserved to a discussion of these three (and maybe more) beta builds only. I am reassembling my 6CW5 amp, and I may post that build either here or in another thread (I haven't decided yet), but I ask that other builders start their own thread.

[nic6paul]

So far I haven't found any real errors on the site. One thing I would suggest for those that order the kit is grab a couple of pieces of paper and label each part with their value and the component number for the board and just adhere them to the paper with some tape. I found this useful with the resistors mainly. The capacitors aren't that difficult but misplacing a resistor could be pretty easy especially the 1/4 watt ones. As I was stuffing the board it was easy enough just to grab it off the paper and place it on the board. I think the resistors took me 15 minutes to place and solder.

[nic6paul]

George any idea on what size fuse would be suitable for the 6CW5 version of this amp would be.

[rknize]

Had a bit of time to stuff the resistors this evening. I followed along with the bottom assembly procedure and didn't notice any errors, though I put resistors on both sides for various reasons. The only comments are really for beginners:

Swapping R2 and R4 seems like the easiest error to make. You do mention it at the beginning, but maybe it's worth using a slightly different R2 value?

It might also be worth it for soldering novices not to solder joined pads until both parts are in (R110 and R111, for example).

Identifying resistors by color code is a good exercise, but the precision resistors might be confusing for some since it is not always obvious which way to read them (1.00k, for example). I've also seen some (not these) were it is hard to tell what the colors are because the resistor bodies are so dark (red looks like brown, etc).

[rknize]

The board is stuffed. A few discrepancies in the parts list for the caps:

C100/C200 are listed as 1000uF@16V but the supplied parts were 1500uF@6.3V. Looks to be the bypass cap for the input tube section cathode, so 6.3V should be fine I expect. Might match the cap in the pictures, but it's hard to tell.

C102/C202 are listed as 47uF@450V but the supplied parts were 82uF. Looks like it matches the picture, though.

[rknize]

I was a little weary of standing the noval sockets on their toes to align them with the octal socket. The tips barely reached the top surface of the PCB. I opted to seat them fully instead. I remember doing this for the SSE and TSE, but I don't remember them being so close to the edge. Maybe it's because I used Belton noval sockets on those?

[nic6paul]

Well I have pretty much got my chassis all built up. The board is stuffed with exception to one socket and I have all the transformers in hand. I still have to reinforce the aluminum top plate and add some brackets so I can keep it mounted to the wood base. Does anyone have any ideas for a decent color for the top plate. I got a whole bunch of free aluminum sheets from a guy building a fish house so the red wasn't really my idea. It is starting to grow on me a little but red really isn't my color.

[Pez]

Hey I think that red looks hot! Any other color with black is not as eye catching except for maybe lamborghini yellow. Stick with the red!

[tubelab.com]

C100/C200 are listed as 1000uF@16V but the supplied parts were 1500uF@6.3V. Looks to be the bypass cap for the input tube section cathode, so 6.3V should be fine I expect. Might match the cap in the pictures, but it's hard to tell.

C102/C202 are listed as 47uF@450V but the supplied parts were 82uF. Looks like it matches the picture, though.

The first 3 amps I built, and the first few parts kits that Sherri put together used the values that you have. They were based on components that I had in stock. I have since ordered 50 sets of exactly the parts shown on the parts list. I retrofitted 2 of my boards which are being used in the dual mono Simple PPP amp. I have also built 2 more boards, which have been tested, but not assembled into amps yet. Many of the pictures were taken using boards built last year.

I was a little weary of standing the noval sockets on their toes to align them with the octal socket. The tips barely reached the top surface of the PCB.

The board with the tube sockets standing on their tip toes has been doing duty as my tube tester / tube matcher. I have stuffed about 50 6CW5's through this board, often multiple times in order to come up with 6 sets of reasonably matched tubes. No issues were seen with the sockets.

[tubelab.com]

George any idea on what size fuse would be suitable for the 6CW5 version of this amp would be.

I have a 2 amp in mine because thats what I could find. I would think that a 1.5 or 1.6 amp slow blow would be a better choice. A one amp doesn't work. It will sometimes blow at turn on.