Second Hellfire Build - EL34

bilbarstow

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My first build went so well, I decided to make a second amp, based upon Randelli's design for the Hellfire. This time around, I went with EL34 power tubes, ECC83s for the preamp and PI tubes. The biggest change was I decided to make this amp with taps for 4, 8, and 16 ohm speakers. This required substituting the Output Transformer with a Hammond 1760E (replacing the single tap 1750E), and providing 3 output jacks. I went with isolated Cliff Jacks this time (reference previous builds discussions about grounding / chassis isolation).

I'm not going to give the full play by play this time as it went largely like the first time, building on the lessons learned and the discussions on the other people's builds.

Here are some pictures :

Mechanical assembly, holes drilled, hardware mounted in the chassis

MechHdwrInst.jpg


Front Panel hardware layout

FrontPanelHdwr.jpg


Turret Board punched and turrets set

TurretBd.jpg


Randelli graciously modified the drawing for me - I wanted to expand the board just a little to leave a little more room around the components.
 

bilbarstow

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To continue the pictures :

Heater Wiring Overall :

HeaterWireOverall.jpg


Heater Wiring detail at the sockets

HeaterWireSockets.jpg


This time I reoriented the sockets to give me access to the opening between pins 1 / 9 to route the heater pairs. I also tagged one side of the pair with yellow shrink wrap to ensure I did not cross-wire them.

Pilot light wiring :

PilotLite.jpg


Power Switch wiring

PwrSw.jpg


Notice the yellow and grey wires from the Power Transformer - folded back and shrink wrapped off (not used).
 

bilbarstow

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More Pics :

Tone Pot, Volume pot, Input jack - basic wiring :

VolToneInput.jpg


Power Tube sockets wiring

PwrTubeSockets.jpg


Output Jacks wiring

OutputJacks.jpg


It got a little cramped in there wiring under the lip of the chassis. But it was worth it, as it provides flexibility in use for the amp, can use pretty much any speaker cab now.

Loaded Chassis

loadedChasis.jpg


And an overhead view

Overhead.jpg
 

bilbarstow

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last pics:

Testing the loaded chassis :

testingChassis.jpg


and in the Head Cab

HeadCab.jpg


I re-used my Epiphone Valve Jr. Head cab for this. Had to flip the box upside down to suit my bottom-mount chassis. I went ahead and used the Back grill for the front - just because it looks "meaner" that way :laugh2:

In use, the EL34s are a little crunchier than the 6V6s in the first amp. It breaks up a little earlier and definitely gets a fatter power tube distortion.

This is what I was shooting for with this variation. I want to be able to run the 6V6 Hellfire for a "Clean" channel, and use a switcher to use the EL34 Hellfire as a "distortion" channel.

As always, this circuit is very quiet - no hum until you hit the deep end of the gain (vol from 11 - 13 !). Great tones and control of loudness with the Master Volume. And it does get LOUD.

Randelli has designed a great circuit / project. I encourage any of you thinking of building an amp to look into it - fun, easy to build, and an exceptional end result !
 

bwillard

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Bill,
Another AWESOME project! I'll bet it was a LOT easier to build the second time!

Ben
 

bilbarstow

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Thanks Ben !

It was definitely easier to build it the second time. I had much more confidence and was able to concentrate on the circuit itself.

You may notice the extra resistor (220K/2W) piggy-backed on top of the Second filter Cap (C5). This is a second bleeder resistor that works better in connection with the "standby" (middle) position of the Choke switch. I piggybacked this to allow me to test this out to see if it went to standby better/faster than without it. This change was as a result of a suggestion from Lyle, along with discussions with Randelli.

It definitely works. Makes the standby time much sooner. I will be adding this to my first board as well. Recommended to other Hellfire owners.
 

bwillard

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Bill,
I'll have to make that modification. That is the only thing that I don't like about my Hellfire!

Ben
 

hipofutura

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Outstanding, Bill! I would never dare show such close up pics of my soldering!

You did a very nice job with the build and looks like Randelli did a great job with the design.

Looks great in the VJ cab. It would be interesting to see that cab in blonde nubtex with gold piping. Would be a beautiful match with the faceplate.

Well done!
 

bilbarstow

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Don, Thanks for the compliment ! an honor coming from you.

I'm not afraid to show my work in closeup, I try for neatness and quality workmanship. I'm really showing the pictures to encourage other potential builders. I jumped into this with little more than the desire to understand and a little experience building simple electronics. I want to encourage others that it is do-able. (but as always, know your safety first !)

I really think that between the multiple threads and the superb plans and documentation that Randelli provides (for FREE, folks !), this is a pretty solid first project for someone to take on. It is just gravy that the amp it produces is very cool as well. A great master volume that provides the ability to play it at low(er) volumes, as well as great clean to crunchy range of tones. So nice I built it twice ! :naughty:

As far as the cab tolex goes ... well this may not be it's forever home. The last one I built a custom solid cherry cab for. I really like that cab design, just did not have the chance to build another one right now. My next project is to take the VJr that came out of this cab and re-work it. When that happens, it may go back into the VJr cab, and the Hellfire may get a ritzier home. So messing with the tolex was a secondary consideration.
 

randelli

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To continue the pictures :

Heater Wiring Overall :

HeaterWireOverall.jpg


Heater Wiring detail at the sockets

HeaterWireSockets.jpg


This time I reoriented the sockets to give me access to the opening between pins 1 / 9 to route the heater pairs. I also tagged one side of the pair with yellow shrink wrap to ensure I did not cross-wire them.

Pilot light wiring :

PilotLite.jpg


Power Switch wiring

PwrSw.jpg


Notice the yellow and grey wires from the Power Transformer - folded back and shrink wrapped off (not used).

Of all the heatshrinkers in the world, bilbarstow, you are the heatshrinkiest!

:cool:
 

randelli

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That looks great Bill!!!

Can I come over and hear it?? I will be in Houston for the rest of this week and looks all next week as well :D Unfortunately I will still have Ginger and the RM from my family reunion in Texas City this week end :thumb:
 

bilbarstow

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That looks great Bill!!!

Can I come over and hear it?? I will be in Houston for the rest of this week and looks all next week as well :D Unfortunately I will still have Ginger and the RM from my family reunion in Texas City this week end :thumb:

Of course you can come over. I always welcome a visit with the Amp Sensei. I'd love for you to hear it, we can compare the 2 side by side.

PM Sent

And heatshrink is cheap and abundant, might as well use it ! Neatness counts !
 

tex_lt

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Of course you can come over. I always welcome a visit with the Amp Sensei. I'd love for you to hear it, we can compare the 2 side by side.

PM Sent

And heatshrink is cheap and abundant, might as well use it ! Neatness counts !


Awesome work bill.....hopefully I will get around to building a hellfire one of these days, and your threads will be quite helpful! :applause:
 

randelli

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I got to spend time with Bill last night and play through both of his HELLFIRES. They sound so great!

He definitely got the mad scientist's seal of approval!
 

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