Building my first 18watt from the ground up.

[spin]

If you turn your tube sockets 45 degrees, they'd all fit better, and you could put them in a single row. Having them in a single row means the heater wires won't be traveling under or around the board. The heater wires can cause issues with noise and such, so keeping them shorter and together usually works out to your advantage.

I'd also suggest using taller standoffs. A little more room will give better airflow around the board.

Thanks,
Josh

-I made some concessions for aesthetics (needed to have the tube labels a certain direction), I have no defense.
-Thinking about using elevated DC heaters if it become necessary, cross that bridge when we get there.
-McMaster-Carr cart going, getting both 3/8" and 1/2" stand-offs to tryout, agree the 1/4" leave no room for wiring, especially transformer wiring after it passes the rubber grommet.

Very creative!

So did you swage and then solder the turrets (on the bottom) to the vias?

Yeah, takes a bit of heat, but appears to be working. First go at it. I made sure to use the cheaper 'Hot Air Solder Leveling' from the PCB manufacturer so the pads and vias would be well tinned. I feared that if I got the nicer gold plated pads, I wouldn't be able to get solder in after the crimp.

[JMPGuitars]

Yeah, takes a bit of heat, but appears to be working. First go at it. I made sure to use the cheaper 'Hot Air Solder Leveling' from the PCB manufacturer so the pads and vias would be well tinned. I feared that if I got the nicer gold plated pads, I wouldn't be able to get solder in after the crimp.

That depends on your iron. You need some good heat/heat inertia to do that without any issues. I use an Aoyue 2703A+ solder/rework station. It's my 5th station (I've been through a few different brands/models), and it's great. Occasionally I need to clean the smoke absorber hose for the iron, but that's been the only thing.

[spin]

New hardware day. Trying these high heat grommets for fun, a little easier to work than the black rubber.

65847452_2107191969410364_6126572141082050560_o.jpg

66195994_2107193932743501_754138592946683904_o.jpg

[spin]

Got a little progress done over the last month, been slow going due to work stuff. New transformer came in last week and I got some time to start working on my nodes this weekend. It's starting to sound decent as well.

TMB Early Voltage.jpg

Bonus chassis work:

Post Paint Chassis.jpg

Early Headshell.jpg

[AussieTim]

I was reading through this post when I noticed Josh,s comment of raising the turret board for better airflow. Which got me thinking as his comments usually do, It occurred to me that the board is basically housed in a sealed aluminium box with no ventilation. So although the notion of providing better airflow around the board is a good one, given there is no airflow through the box would it make any difference? then to take the thinking another step should the chassis be ventilated? it would be simple enough to do but is it necessary? where I live we get some pretty hot summers so I imagine externally venting the chassis would be helpful even the addition of heat sinks or computer style fans to push air around, or is air flow past the chassis in a combo where It would rise from the open back and out the top vent be sufficient
Tim

[Daviedawg]

I always have low and high vents in some form. Some not very big.
The only exception is my reverb unit where the chassis with two valves is above a full width solid ally screen and the tank below. So I just have a partially open back at the top. But I will always vent in some way. No science involved, just observation of what happens if you don't and play for long periods.
One advantage of no vents is you don't waste beer I guess.

Dd

[spin]

Extremely valid point guys.

I did think about it for a little bit prior and came to the following conclusions:
-I don't want to drill holes everywhere, it looks ugly
-It's only 18 watts, how hot could it get? (more on that later)
-None of my Fender clones had ventilation (5w, 50w, 100w) (steel chassis). My 100w Slo-clone is also non-vented (though much larger aluminum chassis)
-The amp isn't inverted like the Fenders, tube heat 'should' radiate mostly up and out not building up on chassis or wood
-Aluminum chassis should radiate up and out as well dissipating PCB heat

What I learned:
-These el84's get hot as hell.
-Cathode bypass resistor gets hot as hell.
-It looks like a lot more space on paper.
-I don't know **** about thermodynamics.
-I might need ventilation on the final version.

[JMPGuitars]

I was reading through this post when I noticed Josh,s comment of raising the turret board for better airflow. Which got me thinking as his comments usually do, It occurred to me that the board is basically housed in a sealed aluminium box with no ventilation. So although the notion of providing better airflow around the board is a good one, given there is no airflow through the box would it make any difference? then to take the thinking another step should the chassis be ventilated? it would be simple enough to do but is it necessary? where I live we get some pretty hot summers so I imagine externally venting the chassis would be helpful even the addition of heat sinks or computer style fans to push air around, or is air flow past the chassis in a combo where It would rise from the open back and out the top vent be sufficient
Tim

Here's a thought. Or two.

Should all components be super close to the chassis, or should many of them be away from the chassis?

Even if the chassis isn't externally vented, what happens with changes in temperature in an enclosed space?

By raising the chassis up slightly, you maintain a safe gap from the chassis. You also allow for static airspace around the circuit board. I usually use 10mm standoffs, but for a bigger chassis I've used as much as 20mm or so.

Most of the heat (assuming no issues or oscillations) will be coming from the tubes outside of the chassis. So make sure your head cabinet has real airflow.

[JMPGuitars]

New hardware day. Trying these high heat grommets for fun, a little easier to work than the black rubber.

I see you have PEC pots in there. I recently bought some to try out in an amp build too. A word of warning though- Aiken said he used to swear by these, but then people complained about noisy pots. Since these are sealed, you can't spray them with contact cleaner to correct that problem.

I usually use CTS pots and generally don't have any issues. I guess we can both see how these turn out for us.

[spin]

New hardware day. Trying these high heat grommets for fun, a little easier to work than the black rubber.

I see you have PEC pots in there. I recently bought some to try out in an amp build too. A word of warning though- Aiken said he used to swear by these, but then people complained about noisy pots. Since these are sealed, you can't spray them with contact cleaner to correct that problem.

I usually use CTS pots and generally don't have any issues. I guess we can both see how these turn out for us.

I picked these up to try as well. Same, I use CTS for most all of my 24mm pot needs. I used clerostat (I think that's how it's spelled) on my Slo-Clone, and those were beautiful. Cost a pretty penny though. I've replaced parts in 40 year old CTS pots, says something about serviceability. I'm 'trying' a lot of things on this 18watt build that I wouldn't normally do, so far so good.

[crgfrench]

The strain relief on the wiring of the BMP board is just a large plated via.

This fx.transposed BMP board is excellent. I'm almost finished my "Lil' Hare Pi" pedal using it. Will post some follow up once it's done. For the 3 sets of wires, I soldered Phoenix Contact's terminal blocks (MKDS 1/2-3.81 HT) and they work beautifully. This way I have screw terminals for power, signal in and out, in order to uninstall & reinstall the board in the pedal box without soldering.

20190815_014948.jpg

[spin]

What do you guys think of these voltages? I'm pretty happy with the sound as of right now. I have compared voltages to the charts and nothing seems too far out given the schematic differences. My TMB V2 section is most influenced by the Mojotone TMB and seems to be somewhat different than what's in the schematic library on here.

Test 5 Voltage.JPG

Schem V1 - low.jpg

[crgfrench]

I like that design. With no grid stoppers on V1 can you tune in WMMR?

You may find you have unbalanced gain coming from the PI triodes. This would likely be due to R13 at 100k. An 82k resistor there would balance it out if you find it to be an issue.

[spin]

I like that design. With no grid stoppers on V1 can you tune in WMMR?

Surprisingly, no. I do currently have a 68k grid stopper on v1a, but not b. Input jacks are: v1a or v1a+v1b parallel. The parallel input has significantly more gain. Learning is fun!

[crgfrench]

Check out from the 22 minutes mark in this video (viz. R13):
https://youtu.be/U6By31V9fDo

[spin]

Productive last couple days. Got the amp built in the final chassis and have begun testing. Very happy so far. I was expecting a fair amount of hum due to the compact nature as well as the heater scheme, but it is remarkably quiet, silent even. Doing some burn in and thermal testing this weekend, wish me luck!

Front Chassis 02.jpg

PCB 01.jpg

Back Open 01.jpg

[crgfrench]

Love the heater wiring. Is it DC?

[spin]

Love the heater wiring. Is it DC?

It is not DC, nor elevated, which is why I was worried about it. The last time I did this parallel heater wiring, I made it DC. I gambled and won this time. We'll see how much hum I end up with once the honeymoon phase of my listening experience wears off.

[crgfrench]

I think Soldano does it that way too.

[spin]

I think Soldano does it that way too.

That was where I picked it up from, I built a SLO 100 a few years back.

soldano 3-9 017.jpg

amp wiring 001.jpg