The Build: Chassis fabrication to power-on

[SoulFetish]

What a great feeling it is to have a soldering iron in hands, to make me feel like I'm actually doing amp work. I had to wait til today because I wasn't even CLOSE guessing how many turrets I would need and had to wait to get more from Allied. Apparently, I didn't want to count?
Anyway, just getting the soldering underway and it feels good; power supply is coming along

[SoulFetish]

update

Can I just say +1 for printed circuit boards

I just finished up all the "on board" wiring connections:




It's important but... a little tedious doing this part. I think I'm really liking the idea of a hybrid pcb/handwired approach. That would have made for much quicker work.
I guess I'm a fan of hybrid techniques, because I thought of a way to make quick component changes when I go live and start testing this amp. This amp's is new and if I need to make changes (which I'm sure there will be a few) because real world results may differ from what I expected, I wanted to be able to make the changes efficiently. So, I "socket-ed" the turret terminals holding the components most likely to be altered or tweaked to get the results I'm after. I soldered some beryllium copper/brass sockets which sit nicely in the turrets to allow me to experiment and breadboard if I need to.



It's a little more work on the front end, but it should really give me some flexibility and save me time if I need to change things. I like to think Bob Pease would be pleased with my contingency plan

One last thought. There are two things that frustrate me when I'm on the bench working. The first– not being able to find a tool which I literally just put down, I haven't gone anywhere to have left it, and it may as well vanished for at least until I don't need it any longer. I mean, it has to be in a (generous) 5' radius, doesn't it? Logically? Nope. It's f*cking GONE. That ever happen to you guys?
I haven't solved that problem yet, but the other thing is when my soldering iron chord gets caught on something or when it (or other leads) gets in the way on my bench. I want to share a cheap, easy, quick trick to keep your cable up and out of the way. If you have a pegboard, go to a Staples (or whatever) and get one of those retractable cheap name tag/card holder things -
like this:


You can hang it from a long pegboard hook and use this to keep the chord out of the way and has a decent range to act as a runner.
Like this:

Problem solved.
Anyway, that's it for tonight. Keep it real

[SoulFetish]

Heater wiring.

[SoulFetish]

After giving up my week and a half long quest to find some great deal or inexpensive cache of RV4 pots in the values I needed (of course, all the same type), I gave up. It was ambitious, I know, but I guess I'm just cheap. So, I bit the bullet and faced up to the fact that I was going to have to pay retail. What the hell, I can't win 'em all. So my pots arrived and I was glad to be back at it!. It was time to wire up some of the front panel.





You may have noticed the empty hole between the last to pots to the right. It's for a common, inexpensive, simple 2PDT toggle switch, which for some crazy reason I didn't have, and thought would just end up showing up? (I can't believe I didn't have one!).
It's funny, so far it's has been the little odds and ends that have been the hair across the ass of this build. A resistor value that I was sure to include in an order, or a small fastener, or common small type of switch that I can't believe I didn't have. This is often what has brought progress to a grinding halt. Okay, that's a little hyperbole, but they're important parts of this that I'm relying on. Whenever I try to take a short cut around it, I usually end up regretting it.
I'm really beginning to see the value in a complete BOM, and inventory check list.
But, what I do have is geeks for friends. So I put out the Bat Symbol, and my buddy Scott sent me this and said "are these what you're looking for?"







(Damn right these are what I'm looking for).
Before too long I was making it rain mini 2PDT in my shop again. I finally got to put the board in and began lining up and cutting the leads to size. I'm starting to get psyched. Check it out, almost looks like an Amp
Finally!! I'm hitting the home stretch!
.

[mozz]

In 100 years, that amp will still be around. Looks very nice. The pots look like the old Allen Bradley type J. What are those caps? Vishay?

[SoulFetish]

In 100 years, that amp will still be around. Looks very nice. The pots look like the old Allen Bradley type J. What are those caps? Vishay?

Yes Sir, MKP1848 series. Thanks for the kind words.
I have some parts comkng today, and Thats the last batch. I think I may be ready to fire it up by the end of the week. Im exited to put it under test and hear this thing. Hey, Ill finally get to play some guitar for a change! Wont that be something

[mikepukmel]

After giving up my week and a half long quest to find some great deal or inexpensive cache of RV4 pots in the values I needed (of course, all the same type), I gave up. It was ambitious, I know, but I guess I'm just cheap. So, I bit the bullet and faced up to the fact that I was going to have to pay retail. What the hell, I can't win 'em all. So my pots arrived and I was glad to be back at it!. It was time to wire up some of the front panel.

......

You may have noticed the empty hole between the last to pots to the right. It's for a common, inexpensive, simple 2PDT toggle switch, which for some crazy reason I didn't have, and thought would just end up showing up? (I can't believe I didn't have one!).
It's funny, so far it's has been the little odds and ends that have been the hair across the ass of this build. A resistor value that I was sure to include in an order, or a small fastener, or common small type of switch that I can't believe I didn't have. This is often what has brought progress to a grinding halt. Okay, that's a little hyperbole, but they're important parts of this that I'm relying on. Whenever I try to take a short cut around it, I usually end up regretting it.
I'm really beginning to see the value in a complete BOM, and inventory check list.
But, what I do have is geeks for friends. So I put out the Bat Symbol, and my buddy Scott sent me this and said "are these what you're looking for?"

......




(Damn right these are what I'm looking for).
Before too long I was making it rain mini 2PDT in my shop again. I finally got to put the board in and began lining up and cutting the leads to size. I'm starting to get psyched. Check it out, almost looks like an Amp
Finally!! I'm hitting the home stretch!
.

Your build quality is a work of art!

[mikepukmel]

Heater wiring.

Again, beautiful job. It looks like solid core, what gauge are you using, is it 18ga?

[nsubulysses]

Hi soulfetish, great build I agree. Inspires me to make a very neat build. Great j0b

[SoulFetish]

Again, beautiful job. It looks like solid core, what gauge are you using, is it 18ga?

It is solid core wire. It's 20AWG/600V wire code UL1015. I also use type MIL-W-76, which is mil spec 1000V wire when I have it. I my opinion, 20AWG seems to be the sweet spot for what we do. 22AWG, is a little to thin and is prone to shifting around, while 18AWG solid core is so stiff when soldered, that if your not careful working with it, you can break some terminals.

[The Dude]

Very tidy build! I hope it sounds as good as it looks. Thanks for the update shots!

[mikepukmel]

It is solid core wire. It's 20AWG/600V wire code UL1015. I also use type MIL-W-76, which is mil spec 1000V wire when I have it. I my opinion, 20AWG seems to be the sweet spot for what we do. 22AWG, is a little to thin and is prone to shifting around, while 18AWG solid core is so stiff when soldered, that if your not careful working with it, you can break some terminals.

Thanks!

[tedmich]

nice build!

You might have to clean those fancy PEC pots eventually...

Randall Aiken has rethought their use:

"caused me to switch to the hot-molded carbon types from PEC, which I now use exclusively. They are extremely well-built units, even better looking than the Clarostat, but more expensive. These RV4 type pots are more expensive than other types, but their sealed construction, reliability, and precision feel makes them worth the extra cost. UPDATE: I have to admit I was wrong on this issue. After having quite a few amps in the field for going on 12 years now, I am starting to see a few complaints of noisy pots from people who own my amps. Normally, I would just tell them to open the amp up and spray some contact cleaner in the pots. Unfortunately, you can't do this with a sealed pot, so you have no choice but to replace the pot. No pots are going to last forever, so you may as well use a cheaper pot like the Alpha, that can be cleaned or replaced for a fraction of the cost of one PEC pot. The Alphas have a nice smooth torque feel to them."

from Technical Q&A
about 10% down the page

Of course I never actually move my knobs so YMMV

In general I try to use conductive plastic or cermet pots over anything carbon but I still prefer CHEAP and love the construction of old RV4s

[SoulFetish]

I would add that the heater wire is 18AWG stranded which is the thickes diameter that will fit in most 9-pin sockets (barely fits as it is).

[mikepukmel]

I would add that the heater wire is 18AWG stranded which is the thickes diameter that will fit in most 9-pin sockets (barely fits as it is).

Thanks SoulFetish. The last thing Im toiling with on a first amp build is getting the right wire. I read someplace that "you MUST use solid core wire..." on the heaters, but then seems lots of builders use 18ga stranded and I haven't heard of any horrible mushroom could things happening with those amps. (would be nice not to burn up a 200.00 transformer the first time around )