n_maher

Hey, my only vested interest in this is making the design work. If there are issues I'd rather know about them now rather than when I flip the switch!

Sorry, missed this earlier, the diodes that we were considering were 6.3V heaters and that still would have meant running an additional transformer. It's my understand that running the rectifier and say the input tube off of the same heater supply is not a good idea at all. Not to mention that in this amp both the input and output tube heater supplies are referenced to B+ and floated above ground. I've run your initial question by the designer and I'll add this information to the query and see what he says. Let's hope there aren't major issues with the PS design as that would put a serious hurting on my hopes of getting this thing running any time soon.

All of those posts are related to a choke input, correct?

Yes, the 193Q is the first choke. Choke input was looked into but given the current requirement (again, this is my understanding) this wasn't possible unless I wanted to get a custom choke made. 300mA? You mean on the downhill side of the first choke? If so I sure hope I can get more out of it than that since the design was intended to produce ~380mA. And while this is a new design a similar one has been used successfully by the designer in the past so we both have a pretty high level of confidence in what has been sketched out so far.

Agreed, that was one of the 3 options that we came up with for the power supply, the reason that it wasn't used is that it would have required yet another transformer (for the heaters). When I post the schematics I'll post that power supply option as well. As with anything DIY this is just one way of doing it and as usual each had their own compromises/sacrifices. The large choke is a Hammond 193Q, the two smaller chokes are Hammond 1193H's. And I just noticed while looking at the schematics that I have the caps mounted in the wrong positions, d'oh!

The way I understand it each rectifier is fed 385V and then the various other stages drop the B+ down to ~300V at the output. While I didn't design the power supply or the amp for that matter I have complete confidence in the guy that did. The B+ requirements are 300V/.4A which made traditional, single rectifier designs impossible and made trafo selection a matter of "can this be made to work" rather than "this one works best".

You know, the first time I read that I saw now instead of not and thought, "Awww, isn't that nice of Vicki to say." Now I'm more like . I'll PM as soon as I have info. There are two heater supplies for the amp (input/output) so that's one set of 4 and there are left and right HV supplies so there are the other 4. What it feels like it needs is a stiff bottom plate to increase torsional rigidity. I've got some 3/4" oak and maple that is high on my list to use. No clue but I also don't care since I'll just be burning it in through use. Somewhere in the 50 to 60lb range. The trafo is 15, the big choke 21, the chassis another 5 then you've got the caps, 2 other chokes and everything else. Justin is mostly correct, they are rectifiers but they are run in parallel rather than separately. The supplies don't separate until after the large primary choke.

I think it's a safe bet that you'll be a fan of the Menace given your main home amp. And I'll check with my supplier and see if he's got any more 6528s, if you're interested. The BFT is a friggen beast, to be sure and can probably be adapted to many a project given the available secondaries. And thanks for the kind words on the aesthetics. I'm not sure it'll win any beauty contests unless you're like me and drool over things like tanks and trains for the shear mass of them. As far as the 6528s are concerned they are somewhat similar to the 6AS7/6080 family of tubes except that they have a 5A heater so they require a pretty non-standard power supply, as Vicki mentioned. I've actually got some pretty cool tubes to roll through this amp including 7236's and some uber rare Bendix tubes that allegedly have titanium in them. I'm sure some of you at this point are drawing conclusions based on the tubes posted as well as other little details I've leaked. You're probably on the right track, I'll leave it at that for now.

Nights 4 and 5: the final PS chassis fab So I got the tube sockets installed last night (I think it was last night...) and after painting a room today finally got back to it and did the panel layout and fabrication. I also tidied up the caps and chokes a bit and removed the labels. I'm hoping that this is the last time that I mount those particular bits. Overall I've very pleased with how things are coming along and hope to start the wiring tomorrow. The PS is really fairly simple as the eventual posting of the schematic will show and does use some nifty bits. My favorite, as already somewhat hinted at is the transformer. It is so unbelievably flexible it's crazy, here's a link to the data sheet. A few pictures and then it's just about sleepy time. Oh, and two more picture to hint at what's coming in the amp section... Imagine these plus these

Yeah, that's kind of what I was thinking as well. The problem being that given the time sensitive nature of this build the priority is to get a basic version working first and add more features later.

This is basically what I was thinking, so the chokes are all rotated 90deg from the transformer. I got the tube sockets mounted last night so I'm one step closer to wiring. Right now I'm going to go mark and maybe drill the holes for the two Lemo connectors, the IEC/fuse module and also the main power switch. I haven't decided if I'm going to have a separate power switch arrangement on the amp side yet, I'm leaning towards no.

Glad to see the amp in another happy home, I still miss it and I'm growing more sure by the day that selling it in the first place was a dumbass thing to do.

Duly noted.

Actually, the ones that I'm using are bi-metal hole saws, specifically made for working with metal. I may be a hack but I do believe in safety first and always use the right tool for the job. Maybe not the best tool, but the right tool nonetheless. And while I'd certainly prefer to be using something like a greenlee punch for this type of work the three that I would need for this project (2-1/2", 2" and 1-3/8") would cost around $320 which makes them decidedly cost prohibitive. It'd be cheaper to have the panel made by FPE, which I may very well do if I decide to do a final version of the amp.

Now that would be a challenge! This is what I'm using:

That's like saying you just woke up for the 8th day in a row.

Does this mean that I finally need to build you a set of cables?

Everything. At least that was the idea that was used for design. I'll post a brief history of how this project came together some time this weekend if I have time.

I'm already realizing that I'm going to have to do something to stiffen the chassis, it's no match for the weight of the iron. I probably won't get to that before FLA but it'll have to happen at some point. The big trafo on the left side weighs about 15lbs and it's model number is "BFT", no joke. And that's the lighter of the two big pieces of iron, the large primary choke on the right weighs 21lbs. It should go relatively quickly at this point or at least it had better if I have hopes of bringing it to CanJam. The power supply is "scheduled" to be done this weekend and then I'll be stuck waiting for the amp chassis to arrive on Wednesday of next week. :fingerscrossed:

Thanks guys, so far so good. No real trick other than using a drill press, drilling the appropriate pilot hole, using the right speed and holding the material tightly in place. I've got a bench-top drill press that makes things pretty easy and I built an over-sized table for it so that it fully supports even stuff as large as this chassis. I'll try and remember to post a picture of it. Heh, I'm quite sure that my workshop and KG's are world's apart when it comes to goodies laying around. I had originally bought this chassis for my Aikido project but have since sold those parts and the buyer didn't want the chassis. It worked out quite well really and the amp will be going in a matching 17 x 12 x 3 chassis. Neither really needs to be that big but I'd rather have room to spare when it comes to routing wires and the inevitable probing during troubling shooting. Cramped space + high voltage = not good for Nate's health.

I'm going to create a thread for this amp since it is my intention at the end of the build to publish the schematic and any relevant details so that anyone who's crazy enough can build this amp. So for now this (and the amp) are a work in progress and just somewhere where I can share pictures. Actual information will come later. Night #0 of PS chassis fabrication: I did a preliminary layout of all of the parts on a large 17" x 14" x 4" Hammond Steel chassis that I happened to have laying around. It seemed big enough so I took rough measurements of where everything was located so that I could tweak them later for better alignment and symmetry. I'm not all that concerned about everything being dead-nuts accurate for this amp build. The look is going to be decidedly industrial, frills need not apply. Night #1 of chassis fabrication for the power supply: I got all of the hole centers marked and drilled a majority of the small diameter mounting holes. Both the transformer and the chokes are mounted on vibration isolating grommets, not strictly necessary but they can't hurt. Came home early the next day from work to break out the 2" hole saw to cut holes for the large motor-run caps and drill the associated mounting holes. Night #2 of PS fab: not much time tonight, drilled a few of the larger holes for wire penetrations in the chassis and installed insulating grommets to prevent wire wear and shorts. Also test fit the caps and small chokes. I erroneously bought a 2-1/16" hole saw so the cap holes are slightly oversized, oh well, there are worse things. I'll pick up the proper saw for the remaining 2, 2" diameter caps in the amp section. Night #3 of PS fab: drilled the remainder of the wire routing holes in the chassis so that I could do a fairly complete mock-up of the iron and caps. All seems to fit well but holy hell this thing is heavy. Tomorrow I'll pick up the remaining bits and parts that I need to complete the PS fab, all that I really need is a 1-1/8" bit for the tub sockets. I could use a stepped bit that I have but even with the drill press that bit gets unwieldy and I'd rather not trash the chassis at this stage.

I'm with you mulveling, I am not a fan of the LOK RCA connectors. I used them once early in my career, never again.

Well, it's not going to be the sexiest thing you've ever seen but should be pretty clean and tidy. It just didn't seem to make much sense to try and make a sledgehammer look like a delicate piece of artwork. And at this stage I'm pretty much planning on having to tear it back down after CanJam to make adjustments and tweaks so the goal right now is to just get it working in time for Florida in a state of build that will not be a complete embarrassment.

I have a majority of the chassis fabrication done for the power supply and started mounting parts last night. I'll be at it again tomorrow night and I'm probably going to take the second half of tomorrow off to work on it. How's that for dedication!?!??! I hope to have the PS done by end the end of the weekend and start the amp next week.

NO EXCUSES!!!