Hellfire Amp Build-along - first build

[bilbarstow]

After following Randelli's thread, I am going to post my progress on building a copy of his design, the HELLFIRE amp.

First, I need to thank Randelli for his generous sharing of his plans and the detailed images that he provided of his build. I had been wanting to do an amp build for myself, but did not just want to build a kit. This seems like the perfect compromise. He has been very supportive and I feel that he has provided enough detail that even a noob like me can follow along.

I don't intend to rehash the ground that he covered in his build thread, but more to document my experience, warts and all, to show what a first build experience can teach. At the same time, the experienced builders here may occasionally have to come to my rescue

I hope to inspire other new builders that are considering a project to finally jump in and get their feet wet (or eyebrows singed, as the case may be ?)

[randelli]

First off, it's randelli - Randelli's my dad...............

Not really; but all seriousness aside I know you will thoroughly enjoy this build - both the experience and the end result. My son really really likes how this one turned out, even with the crap stock speaker. I get the Reaper tonight and then it will be complete.

Good luck! and call me if you have any questions.

*HINT* heater wiring sucks so get it out of the way first!

[bilbarstow]

First steps:

After receiving the plan PDF's and ordering the parts, when the parts arrived, I went to Kinko's and had the drawings printed at 1:1 size.

Cut out the chassis drawing and taped it to the chassis to locate all of the holes that needed to be punched and the mounting holes to drill.

This Epi Valve Jr replacement chassis is pretty heavy aluminum - nice and easy to work with, but I cannot stress enough that you NEED a drill press to punch these holes cleanly. I got the step bits cheaply from Harbor Freight.

The Chassis is open on both ends ( I think I would prefer a full box chassis next time, but this is a direct fit for the VJr cabinet so ). The plywood platform is temporary, just to provide stability while punching the holes on the drill press, and then as a temporary base while I build my head cab (the next project !).



Paper template attached to the turret board for drilling locations



Chassis ready to punch.

[bilbarstow]

Punching the Chassis is not difficult, but it does take some time. The paper template really helps, but I suggest that you verify the tube socket screw holes against the socket retainers themselves AFTER you have punched the holes, don't just go by the template, because lining up the retainers if the socket hole is not exactly centered is important.

Drill 1/8" pilot holes for all of the chassis holes - the step bit needs a centering pilot to start it's cut.



The cheap Step bits actually do a pretty good job and make mostly clean holes. There were some burrs on the inside edges, mostly on the tube socket holes. I cleaned them up with a Dremel with a grinding stone bit.

Hint: don't just go by the size markings on the step bit, test fit the components to the hole sizes as you go along. One of my bit's markings were shifted by a step, and several holes had to be made bigger to fit the components.

Once all the holes were done I test fit / installed all of the hardware to see my progress :



I don't have my fancy faceplate yet, Randelli has ordered it for me and it is on the way. Since I have chosen to build my own cabinet for this when it is done instead of putting it in a VJr cab, I have decided to make mine "upside down" - bottom mounted. Randelli can provide either choice of face plate, as he made both drawings

This means that I have to consider the fact that the switches are reversed, and don't just follow his pictures when I wire it up ! Hope I don't forget.

Next up, Turret Board drilling and staking, test fit of the TB, and beginning the wiring.

[bilbarstow]

Originally Posted by randelli

First off, it's randelli - Randelli's my dad...............

Not really; but all seriousness aside I know you will thoroughly enjoy this build - both the experience and the end result. My son really really likes how this one turned out, even with the crap stock speaker. I get the Reaper tonight and then it will be complete.

Good luck! and call me if you have any questions.

*HINT* heater wiring sucks so get it out of the way first!

How about for all future references, I just use "r" ? - cuz you're gonna get a lot of credit - or cussin' - not exactly sure which yet ?

[Lyle Caldwell]

Originally Posted by randelli

heater wiring sucks so get it out of the way first!

Yes it does. You can make it a little easier on yourself. The power tube and PI (if present) heater wires don't have to be twisted, only the preamp tubes. You can get away with this if none of the preamp circuitry comes near the power tube heaters.

[eddy999]

looking good so far

[randelli]

Looks really clean!

Keep track of your time so we can see how long it will take a first timer to complete the build. I am guessing 8 hours....

[bilbarstow]

OK - so here's the first noob question :



The pots have these little tabs - I 've seen somewhere people said cut them off or bend them back.

My question: Bend back, cut off, is there a preference ? I'm concerned that bending them may mess with the stability / alignment of the pot casing and long term reliability.

They need to be out of the way to allow the pots to sit flush on the chassis and protrude enough to allow for the face plate. Is this another ground point for the pot ?

[rsi]

Those are to keep the entire pot casing from turning when you use the pot. Some chassis have little guide holes drilled for these. You can either drill your own guide holes or break them off.

[randelli]

Just bend it back and you will be OK. That tab is used to get a ground on printed circuit boards and is not needed for your build. These Alpha pots have very soft tabs so you can bend them without causing any damage to the pot.

The tone and volume pots ground to the star ground 1.

[bilbarstow]

Originally Posted by rsi

Those are to keep the entire pot casing from turning when you use the pot. Some chassis have little guide holes drilled for these. You can either drill your own guide holes or break them off.

rsi - now that is the kind of tech trivia that I can completely enjoy.

Now I may have to drill those holes, just to take advantage of the knowledge !

So then the question for randelli would be - If I did drill the "locator" holes, and the tabs were making (incidental) contact with the chassis, would this be a source for the creation of ground loop, since Tone and Volume pots ground at Star 1 ? I assume not, since the pot is already connected there due to the mounting nut and case contact.

[bilbarstow]

And now the special magic Faceplate has arrived :




I think I have all the goodies now. Oh ... and it goes to THIIIIIRTEEEEEN ... take that, Nigel Tufnel

[randelli]

the locater holes would not cause a problem.

HELLFIRE MUST GO TO 13!!

[randelli]

<crickets>

[mudfinger]

Originally Posted by randelli

the locater holes would not cause a problem.

HELLFIRE MUST GO TO 13!!

It's only fitting, after all.

[bilbarstow]

Originally Posted by randelli

<crickets>

I'll give you <crickets> !

I had to drag the drill press back out this morning. Of course, that required stripping out all of the hardware first. Then I drilled the special "locator" holes for the pots, and touched up a couple of the tube socket mounting holes.

Then I was able to drill the Turret board. Staking the turrets comes next.

All the hardware goes back on the chassis (finally got my nuts !)

and then I'll finally be ready to start some soldering. Pics to come soon.

[chriseskew24]

Sweet! Can't watt to see and hear her!

[hipofutura]

What a great project! It's very cool when we share and spread our ideas, designs, and knowledge. Very decent of you randelli to help and contribute like this.

I love the drilling template!! I have yet to figure that out. I do it the hard (slow) way with ruler and pencil.

Can't wait to see how this turns out, and the cab as well.

[bilbarstow]

OK, here are some progress pics:

Locator Holes, Thanks to RSI



And how the pot fits in them:



Turret Board drilled using the template from Randelli's plan documents:



And how it looks after you remove the template :



And the Turret Board after staking it by hand, using a punch and a hammer over a piece of steel for an anvil:



And, because I promised warts and all, it is possible to get a little too over-zealous with the hammer :



I did drill that one out and re-stake it. But they are not easy to get out without damage to the TB, so don't pound them !

[bilbarstow]

Originally Posted by hipofutura

What a great project! It's very cool when we share and spread our ideas, designs, and knowledge. Very decent of you randelli to help and contribute like this.

I love the drilling template!! I have yet to figure that out. I do it the hard (slow) way with ruler and pencil.

Can't wait to see how this turns out, and the cab as well.

hipofutura, you are so right about how cool it is that the people on this board share so much. And Randelli is more than decent - he has really given above and beyond the call. His drawings certainly make it easier, but the pictures and running commentary in his thread are like looking over his shoulder - and the amount of confidence that provides makes this noob pretty hopeful that my first build will be a success !

I've gotten so much knowledge just from reading the threads of this board, and generous contributors like Randelli, Lyle, Hipofutura, and so many others. You can't really buy this kind of education. Thanks to all of you. I just hope to inspire the next person to come along.

Keep watching - let's see how I do. (All feedback greatly appreciated)

[randelli]

Originally Posted by bilbarstow

And, because I promised warts and all, it is possible to get a little too over-zealous with the hammer :

I did that too! Those single turrets are really soft.

Looking good Bill!!!

[bilbarstow]

A little more progress ...

I re-mounted all of the hardware, including the Turret Board, faceplate and added the knobs, just to tease what it will look like when I finally get it together:




And, here is the underside of the chassis, ready to start the Heater wiring, Power wiring and begin the wiring to the turret board :



I know that this is slow progress, but I AM moving forward. Just updating these posts provides motivation. Then I listen to Randelli's demos and try not to rush myself because I want to hear it working !

[randelli]

Looks great so far Bill!

How did the faceplate fit? Mine was a little tight (I think I was off center on one of my pots) so I asked him to add 25/100's to the holes.

THOSE knobs are PERFECT!!!!!

Keep it up!

[bilbarstow]

Originally Posted by randelli

How did the faceplate fit?

THOSE knobs are PERFECT!!!!!

The Faceplate is off just a smidge - it is shifted right by a small amount, probably less than a 1/16th. My fault, I probably got the paper template just a little off before I drilled. Volume pot and input jack were off just a hair also, but a little sandpaper to the edge of the holes fixed that. I'll do final modifications when I get ready to build the head cab. I'm gonna take the faceplate OFF while I do the rest of the build - don't want to scratch the pretty !

As you said, perfect Knobs are hard to find. I've got 3 sets that are no-goes But I do like these as they are different enough to stand out.

[jon47715]

i'm curious what kind of sound you are going for on this Hellfire amp. it immediately brings to mind a super high gain kinda sound.

[bilbarstow]

Originally Posted by jon47715

i'm curious what kind of sound you are going for on this Hellfire amp. it immediately brings to mind a super high gain kinda sound.

jon47715,

You can probably get the best idea of its sound from the video demos in Randelli's original thread , specifically post 260, on page 9.

I'm personally most interested in the clean side with lots of headroom (seems kinda vox-y to me, with it's own character), but I have no doubt that I'll play some with the Master down and Volume up for crunchy gain. And who knows what variety will come from the use of the Tight/loose switch and variations of the Tone.

My driving interest was just to build an amp, not specifically a kit, and to learn about the process doing it. I'll figure out what sounds I can get when it's working (I decided to play along way before he had ever made a noise with his, the project just fit my needs so well)

Randelli has been SOOOO helpful with all of his information and feedback, it is sort of like having a guardian amp angel !

If it is your sort of thing, I invite you to jump on in - the water's fine !

[randelli]

The cleans on the HELLFIRE are super clear and transparant. Think Chili Peppers under the bridge or californication:

&#x202a;Red Hot Chili Peppers - Under The Bridge [Official Music Video]&#x202c;&rlm; - YouTube

‪Red Hot Chili Peppers - Under The Bridge [Official Music Video]‬‏ - YouTube

&#x202a;Red Hot Chili Peppers - Californication [Official Music Video]&#x202c;&rlm; - YouTube

‪Red Hot Chili Peppers - Californication [Official Music Video]‬‏ - YouTube

and the dirt gets into mississippi queen and barracuda territory:

&#x202a;Mountain - Mississippi Queen&#x202c;&rlm; - YouTube

‪Mountain - Mississippi Queen‬‏ - YouTube

You Tube

You Tube

Very useful amp here!

[bilbarstow]

Got the Heater wiring done today :



Heater connections at the Lamp socket with 100 ohm Ground resistors:



Heater Wiring at the tube sockets, 18 Ga wire to the Power tubes, 22 Ga to the Preamp tubes :



Everybody says heater wiring sucks, but I didn't find it that objectionable. Not particularly fun, and making some of those connections under the lip of the chassis was a little tight manoevering, but not SO bad. (of course, I hope I did it right ? - won't know for a bit yet. )

Next up, Power Transformer connections, grounds, and then start on the turretboard.

[randelli]

Looks good so far!

You are want to push those heater wires down tight against the chassis floor to help with hum. You can do it later; but I would check to see that you can at least, now, so that if you need longer wire you can get it in without anything else in the way.

I like the added insulation on the 100R's. Nice touch

Keep up the good work!