The Fullerwell

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JMPGuitars
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Re: The Fullerwell

Post by JMPGuitars »

No worries Dd, I moved it to the right place. ;)
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Re: The Fullerwell

Post by crgfrench »

Thanks guys, I appreciate being a participant, as well as all the work you do behind the scenes to run the site.

Is there an objective set of criteria that one could refer to in determining what characteristics of an amplifier would qualify or disqualify a specimen as a "18W derivative"?

Common characteristics of the Fullerwell as constructed in the Denim Deluxe include:

1) all tube push-pull design, class AB
2) output power is 18 Watts
3) 1x12 cabinet construction [=1974]
4) can run same tube set as 18W (less the trem 12ax7, like Lite IIb)
5) uses Marshall 18W PT
6) uses Marshall 18W OT
7) uses same power tube bias resistor and cap
8 ) input stage and V1 same as Lite IIb except for separated cathodes
9) tone stack similar to lite IIb, with slightly different cap & pot values
10) same current filter caps and resistors
11) same B+ line load resistors throughout
12) same or very similar voltages at all tube pins
13) same rectifier tube
14) same grid stopper and grid leak resistors on power tubes
15) same coupling caps
16) same plate load resistors throughout
17) same power switch and standby switch design
18) same safety fuse at mains
19) same 6.3VAC heater supply to rectifier tube
20) same 6.3VAC heater supply to signal tubes
21) tube phase inverter via 12AX7 or variant

The only dissimilarity of any substance is the PI is set up as Cathodyne rather than LTP. That disqualifies it?

I just noticed that conger has a post in the 18watt Tech Discussion forum about an 18Watt with a cathodyne PI and the same preamp setup as mine, running 6V6 output tubes; surely the Fullerwell belongs here if that does, and it's been there for over a decade?

Best regards and thanks for considering this,

Craig
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Re: The Fullerwell

Post by crgfrench »

18 Watt Blues
(To the tune of crossroad blues)

I built my own amplifier, cause I need 18 Watts
I built my own amplifier, cause I need 18 Watts
It wouldn't make no noise, the tubes were smoking hot.

Oh I connected a Celestion, tried to make some sound
Oh I connected up a greenback, tried to make some sound
It wouldn't make no music, just like it's powered down.

Plugged in a brand new triode, and that thing started to howl
Yeah, I plugged in a brand new Mullard, that thing started to howl
Electrons off the cathode, pentodes rumble and growl.

It's got gain it's got gain, and tube distortion too
It's got gain it's got gain, and tube distortion too
Old lady shouting "turn it down", it's just too loud for you.

Plugged in my stratocaster mama, sounds like the hounds of hell
Plugged in my stratocaster baby, sounds like the hounds of hell
Cause you know that circuit honey, is called the Fullerwell.
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Re: The Fullerwell

Post by crgfrench »

Getting back to the first Fullerwell circuit, it's in my "Denim Deluxe". One nice thing about this 1x12 cab is it uses a black t-shirt for a speaker grille, and the front pocket is handy for stashing your Lucky Strikes.
20190612_145649.jpg
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Re: The Fullerwell

Post by crgfrench »

crgfrench wrote:
Fri 02/22/19 5:54 pm
... So, up it goes, erect and vertical and my 0.68 uF bypass cap standing up next to it in the jumper hole. ..I put a loop in the ground leg of the cap to solder the resistor low side into.
I am not happy with this vertical mounting; am going to re-solder it in the normal lay-down style.
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Re: The Fullerwell

Post by crgfrench »

Build #1 was the Denim Deluxe 1x12 combo, it used a prototyping board;

I'm midway through build #2, the Blues Briefcase 1x10 combo, it uses the TubeDepot 5E3+ PCB;

I just designed my Turretboard for Build #3, the Hellhound 1x12 combo.

This is a DIYLC file I submitted to Doug Hoffman for drilling on his CNC machine, it's about $18 with turrets installed. It's a 9.5" x 3.125" board with 35 turrets; you could also make it with eyelets instead with this same template.

If anyone uses DIYLC and would like a copy of my board file, just DM me and I'll be happy to share it freely.
Fullerwell V1 DrillTemplate HoffmanCNC.png
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Re: The Fullerwell

Post by JMPGuitars »

Why don't you make the board yourself? Drilling/installing turrets isn't that hard. Especially if you made a template for drilling.
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Re: The Fullerwell

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JMPGuitars wrote:
Thu 06/27/19 6:49 am
Why don't you make the board yourself? Drilling/installing turrets isn't that hard. Especially if you made a template for drilling.
I think I will next; but Hoffman makes it so easy and cheap to just send him the file, I sent him the custom layout last night at 1:30am and he shipped the completed board to me at 8:30am! It was seventeen dollars and change, seemed very reasonable.
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Re: The Fullerwell

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crgfrench wrote:
Thu 06/27/19 9:13 am
I think I will next; but Hoffman makes it so easy and cheap to just send him the file, I sent him the custom layout last night at 1:30am and he shipped the completed board to me at 8:30am! It was seventeen dollars and change, seemed very reasonable.
It's definitely reasonable. Post some photos after you get it.
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Re: The Fullerwell

Post by crgfrench »

Sure will Josh, thanks. I was originally planning to buy the board and turrets and then do all the drilling and swaging on my drill press, but then I saw how incredibly cheap it was to just have Hoffman fab it for me; here is the cost breakout:

Board material: $7.13
35 turret lugs: $5.35
Labor - Drill 35 holes: $2.80
Labor -Install 35 turrets: $2.45
Shipping First Class USPS: $5.22

The total labor is about the cost of a Starbucks cold brew. I think I would have been stupid not to have him do it (other than, I'm sure it's enjoyable and satisfying to do it myself).

Will post some pic when it arrives and when I install the passives on it.
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Re: The Fullerwell

Post by crgfrench »

The Hoffman board arrived, here it is next to my current Fullerwell build for the blues briefcase. Solid 1/8" thick board.
20190701_091857.jpg
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Re: The Fullerwell

Post by colossal »

Very nice turretboard!
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Re: The Fullerwell

Post by crgfrench »

The good folks at Wattkins kindly added the Fullerwell (Denim Deluxe version) to their menu for the Universal PCB (available at Tubeface); it's the 12th schematic in https://drive.google.com/file/d/1ApurBu ... p=drivesdk
Denim Deluxe UPCB schematic.png
I'd say that is quite an improvement over my hand-drawn original!
Fullerwell Schematic.png
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Last edited by crgfrench on Fri 07/05/19 10:20 pm, edited 1 time in total.
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Re: The Fullerwell

Post by crgfrench »

JMPGuitars wrote:
Thu 06/27/19 11:56 am
It's definitely reasonable. Post some photos after you get it.
Trinity 18 bare turretboard: $55 what???
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Re: The Fullerwell

Post by JMPGuitars »

crgfrench wrote:
Thu 07/04/19 3:55 pm
JMPGuitars wrote:
Thu 06/27/19 11:56 am
It's definitely reasonable. Post some photos after you get it.
Trinity 18 bare turretboard: $55 what???
I don't shop there, but the page is confusing; it's hard to tell if that includes components or not. It might?
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Re: The Fullerwell

Post by crgfrench »

That's just for the board with turrets installed. Could get 3 custom turret boards from Hoffman for that price.
Loaded with components, the Trinity 18 board is $120.

Weber Turretboard: $19 https://www.tedweber.com/6m18fb
Last edited by crgfrench on Mon 07/08/19 7:19 am, edited 1 time in total.
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Re: The Fullerwell

Post by crgfrench »

Over at Wattkins, jamesrr has kindly worked up the layout for the Fullerwell (Denim Deluxe version), it's the 7th page in https://drive.google.com/file/d/1PuCY0M ... j87Ld/view .

So, along with his schematic, that would be a good way to build one on the Universal PCB.
I'm going to give that a try for build #4. The PCB is available at Tubeface.

I'm very grateful to jamesrr for his great work.
Fullerwell Universal PCB Layout .png
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Re: The Fullerwell

Post by crgfrench »

Here is my detailed view of how to build the Fullerwell circuit on the Wattkins Universal PCB; this version has an off-board chassis mounted EZ81 (not shown here).
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Re: The Fullerwell

Post by JMPGuitars »

Looks like you could do a SS rectifier on there too.
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Re: The Fullerwell

Post by crgfrench »

Yes that board is very flexible! It also accommodates cathodyne (as here), paraphase or LTP PIs and cathode bias (as here) or fixed bias. 1 channel or 2 channels, octal or noval tubes, etc...
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