The Fullerwell

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

Moderators: CurtissRobin, colossal, zaphod_phil, Daviedawg, Graydon

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

Fullerwell #4 on a Wattkins Universal PCB
20200409_134522.jpg
Fullerwell #5 on a revised 2"x6" breadboard protoboard
20200423_201922.jpg
You do not have the required permissions to view the files attached to this post.
0 x

thesmokingwings
Unrated
Posts: 1
Joined: Sat 05/02/20 7:56 pm

Re: The Fullerwell

Post by thesmokingwings »

This is my first post here, and wanted to say this particular thread is the reason I joined. I am a member of a few tube builder groups on FB, and while there is no shortage of help there, your dedication to this series of builds is very inspiring.

I have probably 10-12 Hammond 18(ish) watt platforms from organ tear downs, and have been wanting to try my first PP amp with one or two of them (I have only built SE amps so far). I hope you continue to inspire and I will be starting one of your builds very soon. Thanks again.
1 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

Completed board #5
20200427_144638.jpg
20200502_234920.jpg
You do not have the required permissions to view the files attached to this post.
1 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

thesmokingwings wrote:
Sat 05/02/20 8:03 pm
... this particular thread is the reason I joined... your dedication to this series of builds is very inspiring.
Thanks very much. It's a nice community. Best of luck with your builds.
0 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

Well, it had to be done. Here is a Fullerwell with a LTP PI. I put it on Terry Stinger's "Baby Will" PCB. The standard Baby Will is a LiteIIb so I'm referring to this as a Lite2F ("F" for Fullerwell). I'm using the balanced PI but you can make it with equal plate load resistors if you prefer unbalanced. This particular board doesn't easily allow for splitting the V1 triodes into independent channels, so this "Fullertail" doesn't have individually-voiced channels the way my usual Fullerwell circuit would.
Fullerwell LTP.png
You do not have the required permissions to view the files attached to this post.
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Post by JMPGuitars »

crgfrench wrote:
Mon 05/04/20 1:28 am
This particular board doesn't easily allow for splitting the V1 triodes into independent channels, so this "Fullertail" doesn't have individually-voiced channels the way my usual Fullerwell circuit would.
Lighterwill?
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

Today I designed a tonestack for the Fullerwell circuit.
This inserts between the gain triode and the PI triode of V2.
The Pre-PI MV is already there now, just adding the TMB.
All of the components are P2P on the pots.
I'm going to implement this in my Evil Twin build.
Fullerwell P2P TMB.png
Here is a short video of my design process: https://youtu.be/RHZD43EHzpI
You do not have the required permissions to view the files attached to this post.
Last edited by crgfrench on Sun 05/10/20 12:14 pm, edited 1 time in total.
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Post by JMPGuitars »

You prefer cut mids?

Yours is the green one, compared to ZP's tone stack:
tone-curves.jpg
You do not have the required permissions to view the files attached to this post.
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

I'm not a huge fan of the Baxandall flat mid profile, but you can get the characteristics you're showing with my setup with Bass @ 10%, Mid at 80% and Treble at 65% or so. Your model shows way more Low end rolloff than my design allows (with the controls centered). Here, see this: https://youtu.be/RHZD43EHzpI
1 x

User avatar
Bieworm
Verbose Moderator
Verbose Moderator
Posts: 2287
Joined: Mon 02/10/20 8:24 am
Location: Belgium

Re: The Fullerwell

Post by Bieworm »

crgfrench wrote:
Sun 05/10/20 12:00 pm
I'm not a huge fan of the Baxandall flat mid profile, but you can get the characteristics you're showing with my setup with Bass @ 10%, Mid at 80% and Treble at 65% or so. Your model shows way more Low end rolloff than my design allows (with the controls centered). Here, see this: https://youtu.be/RHZD43EHzpI
Wow Craigh!!! Did you play that? Crazy good stuff man! 👍👍👍👍
1 x
"THIS should be played at high volume..preferably in a residential area"

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Post by JMPGuitars »

I don't have time to look at a video right now, but both circuits were compared with the knobs at 50%. Comparatively, yours has lower mids across the extremes. It seems that's your preference, which is fine. A friend of mine hates mid focus too.

Here's both circuits with the knobs at 50% and all at both extremes:
compare.jpg

Obviously there's some flexing between the extremes (and not moving them all to extremes at once), but not that significant.
You do not have the required permissions to view the files attached to this post.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

The reason Marshall, Fender, Vox and a lot of other folks include a mid-notch in the EQ is that most guitar pickups generate excessive mids. Nothing wrong with a flat EQ setup, just depends on what each person likes the sound of.
0 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

If you have a chance to watch the video, be sure to enable captions. It's all narrated in the captions.
0 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

Bieworm wrote:
Sun 05/10/20 1:12 pm
Wow Craig!!! Did you play that?
Aw thanks but I did not play the music -- that's just Free Youtube Audio available in the editor. The first track is called "Clash of Gods" by Quincas Moriera; the second track is "To the Sun and Back" by TrackTribe.
0 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

JMPGuitars wrote:
Sun 05/10/20 4:15 pm
both circuits were compared with the knobs at 50%.
Something's off with your parameters, my bass doesn't go nearly that low dBs at 50%.

If you squint at just the green lines in your chart though, I like how mine looks like an angry Hawaiian God of surf and volcanoes.
0 x

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

JMPGuitars wrote:
Sun 05/10/20 4:15 pm
Here's both circuits with the knobs at 50% and all at both extremes:
Hi Josh -- thanks for taking the time to model that. I think the reason your results are showing the steep bass rolloff (typical of Marshall, but reduced in my stack) is you may have modeled it with the original (Marshall) 0.022uF Bass Tone Resistor, rather than the 0.22uF I am using. One other thing I just realized is, even though I have a 10k Mid pot in my layout (which gives a deeper mid scoop), I actually left that pot at 25k when I modeled it in the video, and it has less mid notch in the video, closer to the ZP profile.
1 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 3955
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: The Fullerwell

Post by JMPGuitars »

crgfrench wrote:
Thu 05/14/20 11:02 am
Hi Josh -- thanks for taking the time to model that. I think the reason your results are showing the steep bass rolloff (typical of Marshall, but reduced in my stack) is you may have modeled it with the original (Marshall) 0.022uF Bass Tone Resistor, rather than the 0.22uF I am using. One other thing I just realized is, even though I have a 10k Mid pot in my layout (which gives a deeper mid scoop), I actually left that pot at 25k when I modeled it in the video, and it has less mid notch in the video, closer to the ZP profile.
Oops. You're probably right about that cap. Reading is hard sometimes. ;)
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright

Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info


Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

User avatar
zaphod_phil
Builder, Admin
Builder, Admin
Posts: 15208
Joined: Wed 03/19/03 2:00 am
Location: YYZ

Re: The Fullerwell

Post by zaphod_phil »

crgfrench wrote:
Sun 05/10/20 4:55 pm
The reason Marshall, Fender, Vox and a lot of other folks include a mid-notch in the EQ is that most guitar pickups generate excessive mids. Nothing wrong with a flat EQ setup, just depends on what each person likes the sound of.
Who can say what measure of mids is excessive? It's well known that the sweet spot for lead guitar is in the midrange, and also for human voice. Unless we're talking about modern metal. That needs a very scooped sound.
3 x
Nature abhors a clean tube amp

User avatar
crgfrench
Frequent poster
Frequent poster
Posts: 827
Joined: Fri 04/27/18 3:02 am

Re: The Fullerwell

Post by crgfrench »

zaphod_phil wrote:
Sun 05/17/20 6:04 pm
crgfrench wrote:
Sun 05/10/20 4:55 pm
The reason Marshall, Fender, Vox and a lot of other folks include a mid-notch in the EQ is that most guitar pickups generate excessive mids. Nothing wrong with a flat EQ setup, just depends on what each person likes the sound of.
Who can say what measure of mids is excessive? It's well known that the sweet spot for lead guitar is in the midrange, and also for human voice. Unless we're talking about modern metal. That needs a very scooped sound.
Yep it's subjective -- Tom Scholz used a peaked mid setting on the MXR 6 band EQ he used with his "Hyperspace" pedal. And I love that tone too.
0 x

Post Reply