n_maher

I haven't heard enough to be able to compare but someday I'll own another beta22, preferably of the balanced variety. Commercial gear just isn't my thing.

Would it be too evil of me to just remove a couple options from the poll?

That's cold man, just cold.

That's all the hard mounted parts but there are definitely a few more (just resistors and caps) to go that will be wired into the circuit and either attach to the tube sockets, terminal strips or otherwise. I ended up adding a second terminal strip last night to use as a grounding point. I drew up a wiring diagram for the whole amp and I just wasn't happy with how things were being routed and by the number of connections that I was having to tie to a single point. This is mostly because as a starting point the ground of the amp is going to be floated and not tied to the chassis while the amp chassis will be tied to AC ground via the umbilical cord. We'll see what I get for hum, hey at this point I'd be happy with hum, and then figure out if I need to work on an alternate grounding scheme. I'm pretty sure that there was no way this was ever going to be a single chassis amp. Here's to hoping I can get the wiring finished up tonight and maybe test it tomorrow night. A box of tubes just arrived so I've got my test tubes ready to go. Nate

Wiring will commence withing the hour, but first a couple of pictures since fabrication is now complete baring the need for another terminal strip. I haven't quite made up my mind about that just yet. I couldn't resist mocking it up with tubes Upskirt

I hope that it isn't that ghetto looking to you guys.

Very nice work, man. Those look seriously sweet.

Yeah, I have a press and I've got a vice so really it shouldn't be all that bad. Just be a bummer if I torch a $30 knob from THL that I don't even want to use for this project but it's the only one that I have on hand that will really work w/ the rest of the project (scale wise).

In a word, no.

Day/Night 9: no pictures tonight, mostly because I had to stop mid-drilling for fear of waking my wife and unleashing the wrath. But today I managed to get both power umbilical cords built and just about all the rest of the chassis fabrication done. All that's left for tomorrow night is to finish drilling the power inputs (less than a half hour) and then it'll be time to start installing all the big parts so that wiring can begin. With a little luck I'll get that started tomorrow night. With a lot of luck I'll have all of the wiring finished up Tuesday night and might get to fire this sucker up Wednesday... Oh, and wish me luck as tomorrow night I get to try and drill out a knob to fit the shaft extension that I have. The extension that I have is 1/4" and the knob is 6mm (.2362") and there's no way that I have time to try and find another extension kit and also hope that it fits the mounting holes that I've already drilled.

Ok, back on topic. Nights 7 and 8: amp fab continues. Cut thumb aside I really did make some half-way decent progress tonight. First things first I needed to enlarge the holes that I'd drilled for the Johnson tube sockets. I guess that these are supposed to be mounted from the underside but that would make using the various output tubes that I have in mind a giant hassle. Basically it'd mean finding a way to mount them in the same location that would require 1-3/4" access hole for the tube base. Uh, that's not going to work at all. But with the help of a few folks here and my local hardware store I found all the things that I'd need to mount them on the top of the chassis which I think looks 10x better anyway. Also, after a few conversations with Pete we decided that my plan of running parallel 50W resistors to both help with temperatures and also run the resistors conservatively was a good plan. So a little more work with Autocad and I'd found a way to mount them such that my existing layout wouldn't require modification. That's a damn good thing since modifications at this point would involve overnight shipping and tossing what I have in the trash can. So after enlarging the tube socket holes I got down to the business of laying out the resistors in their predetermined locations and also laying out the mounthing holes for the two caps at the rear of the chassis (local B+ caps). Then it was just a matter of drilling 20 or so holes and the bulk of the top panel fabrication is now complete. I installed the resistors and the sockets to make sure that everything was fitting as intended and decided to call it a night. Tomorrow is front and rear panel time, with all round holes that should go pretty quickly. I suppose this wouldn't be complete without a few pictures. Custom Holes (not sexy, but functional) Socket and Resistor Mock Up Holes Drilled Top Layout Preview I Hope These Resistors Are Big Enough That's it for tonight, but wait, a preview of things to come...

They make silver vinyl?

Damnit, I meant to Season's Pass that and forgot.

Update: hour 783.216 - rich colorful sound with good tone and separation. Like all good burn-in reviews I haven't actually spent any time listening to the amp yet. Ok, a successful lunch time trip to the store yielded both rubber o-rings to use as spacers and RTV silicone to use as well. No black available so I had to settle for red. Devil colored RTV works for me. Also managed to put in a call to my tube pimp and order the last of the tubes that I want to have available for the trip to FLA. It's a damn good thing that I have in no way attempted to track what I've spent on this project. I'm guessing that the power supply has the better part of $500 or so into it not counting tubes. And the amp, while less expensive in terms of parts will be a lot more in terms of tubes. The race to CanJam continues...

Reason #2 not to use them.

A little bling for this amp but something worth considering if I can't get the others to work.

I care and actually have some nice, normal octal sockets I just didn't think it was going to be as much of an issue using the Johnson sockets. Now that I've got 1-1/2" holes in the chassis my options moving forward are somewhat limited unless I start fabing mounting plates to hide the over sized holes and I think that the rtv is a better solution.

The first brand that I used cut a pretty nice hole and with a correctly sized pilot seemed to track really well. I'm sure if I'd taken my time and fussed with it even more I could have gotten really good results. The second, HD branded bit was a serious POS and did nowhere near as good a job. That's exactly what I'm hoping to find. I just want to be able to find a data sheet first and confirm electrical insulation/isolation. [edit] Like this:

All good suggestions but as usual time and availability are the limiting factor. Fabrication of the amp chassis absolutely has to be done by the end of the weekend and really I'd like to be wiring before Monday night. I'm going to head to the local HW store at lunch and see what I can find. I like the idea of using some sort of caulking-type product since the size/shape of the bottom of the socket isn't perfectly round so I'd have to use a glue of some sort anyway. I don't think you're seeing the hole picture (no pun intended), the sockets sit on top of the chassis so the contacts on the bottom run through the hole in the chassis and there's less than 1/16" clearance which makes me nervous. The Johnson tube sockets that I'm using (second guessing this choice big time) are a pain to work with for this reason, there's no way to bottom mount them and be able to use the output tubes that I want to. The socket pictured below is pretty similar:

I'm investigating a product right now called pyrosealant. And we were thinking the same thing with the silicon caulking. There's no room for washers since anything that has an I.D. of 1-1/2" is going to have a huge O.D. and not fit in the hole. I'm working on some hand filing to slightly enlarge the hole that I drilled but I definitely want a physical layer of separation between the socket and the bare metal edge of the hole.

I've used that trick before. Thankfully this one wasn't that deep and didn't want to open up so I was able to leave well enough alone and treat it later with just a band-aid. My real challenge for the weekend is figuring out how to isolate the tube sockets so there's no danger of them trying to short on the chassis. I don't think that hot glue will hold up to the temps that these things will be running at...

It might be hot enough to make gravy on top. The cathode resistors for the output tubes look like this... Well, it's a limited run show so enjoy it while you can. I'm hoping to make big progress this weekend although my wife has other plans for my time.

I like sleep way too much to ever go without it for no good reason. But to answer the question I don't think I've ever gone more than 36hrs or so without at least a couple hours of shut eye.

Well between last night and tonight I'm beginning to question whether or not the amp gods are on my side. Last night's snafu is already documented but get this - so I duck out of work 10 min. early so I can run by the hardware store (which closes at 5) and pick up a replacement hole saw. Any guesses as to what size they're currently sold out of. SONOFABITCH! And the pisser was that I had 20 minutes to deal with this before I had to be at another meeting. So I run to Home Depot aka the friggen devil to see if they have anything. Ok, so they've got pre-packaged craptacular looking hole saws so I grab a 2-1/2" set and then look twice. "Dang, that looks smaller than 2-1/2", but it has a label and everything." Not wanting to be f'ed twice in one day I crack open the package and low and behold it's a 2-1/8" bit. I cannot begin to imagine how angry I would have been if I'd gotten it home and found that out at 9pm. So, I go back to the isle and select the right bit and drive pieces separately and I'm headed back to the register with 2 min. to spare. Fast forward to 9pm and the resumption of my hole cutting activities from the previous night. The third hole in the chassis, which was 90% done when the first bit gave out finishes up just fine. The fourth hole, yup, this HD bit sucks ass, fights me all the way. I manage to get it done but it leaves a slightly larger hole than the other three. Oh, and the burr that it leaves around the inside of the hole proceeds to slice my thumb, awesome. So for the rest of the evening I get to fight with trying not to bleed on the amp and bits since the cut is about the equivalent of a nasty paper cut and not worth doing anything about. Anyway, enough pissing and moaning from me for one night. All of the large diameter holes are now drilled and the front four output coupling cap positions have the mounting holes as well. The tube socket holes are going to require some manual enlarging to ensure that they don't short against the case (more on that another night) but that shouldn't be all that time consuming. But no one cares about any of this, show us the pics man, show us the pics!! Blank Canvas Real Nerds Do Full Scale Cad Drawings Mock Up As of 9:30 (more mock up) As of 11:00 (output caps provisionally mounted)

Happy Birthday Ethan!