The Fullerwell

18watt-specific Tech Talk - Building, Fixing, Parts, Mods...

Moderators: CurtissRobin, Daviedawg, Graydon, zaphod_phil, rock_mumbles

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1368
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Postby JMPGuitars » Sat 05/18/19 8:30 am

crgfrench wrote:
Sat 05/18/19 6:26 am
Yes they both came with the mounting hardware. You can see it in the second image.
I don't see the metal plate, it should be on top above the rubber ring.
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
Amp Tools & Test Equipment
(anti)Social: Facebook · Instagram

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Sat 05/18/19 10:03 am

JMPGuitars wrote:
Sat 05/18/19 8:30 am
crgfrench wrote:
Sat 05/18/19 6:26 am
Yes they both came with the mounting hardware. You can see it in the second image.
I don't see the metal plate, it should be on top above the rubber ring.
There is a metal plate it's just underneath in this image -- it's not mounted in yet I was just showing a possible mounting position here. These each came with a bolt, washer, lockwasher, nut, 1 rubber ring (not 2) and 1 metal plate. The plate is dished rather than flat. If 2 rubber pieces are required it would be easy enough to make some extras; there is shielding around the coils so I was planning to just go rubber on bottom and plate on top. Not a bad idea to add a rubber disc on top too though -- thanks!
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1368
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Postby JMPGuitars » Sat 05/18/19 3:41 pm

Ah, you tricked me. :wink: Double check that there isn't two. My most recent toroid transformer had the two rubber rings together so perfectly it looked like one until I peeled it apart. The non-flat plate is normal.

Edit: I just looked back at your photo. It does look like two rubbers.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
Amp Tools & Test Equipment
(anti)Social: Facebook · Instagram

roadshow
Newbie
Newbie
Posts: 33
Joined: Mon 02/12/18 6:19 pm

Re: The Fullerwell

Postby roadshow » Sat 05/18/19 4:13 pm

Not having used a toroidal transformer before, after reviewing the spec sheet for the one in question:
http://www.antekinc.com/content/AS-1T275.pdf

For 550V you'd drive both pairs of red/black primaries and tie the yellows together and run off of the whites?

Does each pair of red/black primaries drive one of the 6.3V for tube heaters?

What's the purple wire for?

Thx...
0 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Sat 05/18/19 5:22 pm

20190520_003520.jpg
roadshow wrote:
Sat 05/18/19 4:13 pm
Not having used a toroidal transformer before, after reviewing the spec sheet for the one in question:
http://www.antekinc.com/content/AS-1T275.pdf

For 550V you'd drive both pairs of red/black primaries and tie the yellows together and run off of the whites?

Does each pair of red/black primaries drive one of the 6.3V for tube heaters?

What's the purple wire for?

Thx...
So on the primary side you wire black to black and you wire red to red, blacks connect to 115VAC neutral line and reds connect to 115VAC hot line, purple connects to earth ground.

On the secondary LV side blue/ green is filament heater supply 6.3VAC;

On the secondary HV side connect one white to yellow for center tap and the end white & yellow gives you 275+275VAC
You do not have the required permissions to view the files attached to this post.
Last edited by crgfrench on Sun 05/19/19 11:40 pm, edited 1 time in total.
0 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Sun 05/19/19 11:06 pm

JMPGuitars wrote:
Sat 05/18/19 3:41 pm
Double check that there isn't two. My most recent toroid transformer had the two rubber rings together so perfectly it looked like one until I peeled it apart. The non-flat plate is normal.

Edit: I just looked back at your photo. It does look like two rubbers.
Yes -- I finally had a chance to look again and there are 2 rubber discs with each transformer.
1 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Mon 05/20/19 12:27 am

crgfrench wrote:
Sat 05/18/19 5:22 pm
20190520_003520.jpg
roadshow wrote:
Sat 05/18/19 4:13 pm
...after reviewing the spec sheet for the one in question:
http://www.antekinc.com/content/AS-1T275.pdf

Does each pair of red/black primaries drive one of the 6.3V for tube heaters?
On the secondary LV side blue/ green is filament heater supply 6.3VAC;
Note, although the datasheet and my wiring diagram show 2 pairs of blue and green wires on the secondary, the toroid I received has a blue-green pair followed by a brown-orange pair; use the former for the pre & output filaments and the latter for the EZ81 filaments.
20190520_011659.jpg
You do not have the required permissions to view the files attached to this post.
0 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Mon 05/20/19 12:31 am

JMPGuitars wrote:
Sat 05/18/19 3:41 pm
Ah, you tricked me. :wink: Double check that there isn't two. My most recent toroid transformer had the two rubber rings together so perfectly it looked like one until I peeled it apart. The non-flat plate is normal.

Edit: I just looked back at your photo. It does look like two rubbers.
2 rubbers are safer than 1 rubber!
1 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1368
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Postby JMPGuitars » Mon 05/20/19 6:21 am

crgfrench wrote:
Mon 05/20/19 12:31 am
2 rubbers are safer than 1 rubber!
That transformer won't be feeling a thing.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
Amp Tools & Test Equipment
(anti)Social: Facebook · Instagram

Daviedawg
Superior Amp Tech
Superior Amp Tech
Posts: 518
Joined: Fri 01/08/10 2:00 am
Location: Scotland

Re: The Fullerwell

Postby Daviedawg » Tue 05/28/19 4:47 am

Just to reaffirm what has been said on a thread at PPWatt.com, this site was set up and has been managed over the years for discussion of the Marshall 18 watt design and derivatives. The Fullerwell discussions have been very interesting with plenty food for thought as well as there being a clear desire for detail knowledge. So the thread has stayed here and run. But the design would not strictly be deemed a derivative of the Marshall 18 Watt.

Dd
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1368
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Postby JMPGuitars » Tue 05/28/19 6:40 am

No worries Dd, I moved it to the right place. ;)
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
Amp Tools & Test Equipment
(anti)Social: Facebook · Instagram

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Tue 05/28/19 8:02 am

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
2 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Wed 06/05/19 8:25 pm

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.
1 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Wed 06/12/19 2:01 pm

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
You do not have the required permissions to view the files attached to this post.
1 x

User avatar
crgfrench
Occasional poster
Occasional poster
Posts: 268
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Postby crgfrench » Thu 06/20/19 10:43 am

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.
0 x


Return to “18watt Technical Discussion”

Who is online

Users browsing this forum: No registered users and 3 guests