Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Amp tinkerers and people who aren't afraid of 700 volts or so in here....

Moderators: Slowy, Capt. Black

User avatar
Bg
Site Admin
Posts: 43187
meble-kuchenne.warszawa.pl
Joined: Fri Sep 05, 2003 12:13 am
Location: Auckland
Has liked: 2254 times
Been liked: 3873 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Bg »

Mattallica wrote:The blue tolex is nice. There's enough black and tweed around the place already
and banned....
So, is that low alcohol or no alcohol at all? mmmm, no alcohol, do you want to try it? Noooooooooo.

User avatar
Jay
Vintage Post Junkie
Vintage Post Junkie
Posts: 7761
Joined: Sat Sep 25, 2010 9:35 pm
Has liked: 1630 times
Been liked: 1297 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Jay »

Bg wrote:vinyl is a complete PITA to apply, you'll find the tolex much easier and it will turn out much better.
Yes, I don't know why I went that way :crazy: Anyway, there's always the TolexMeister just across the border :)
When faced with quality, I recognise it every time.

User avatar
Bg
Site Admin
Posts: 43187
Joined: Fri Sep 05, 2003 12:13 am
Location: Auckland
Has liked: 2254 times
Been liked: 3873 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Bg »

jvpp wrote:
Bg wrote:vinyl is a complete PITA to apply, you'll find the tolex much easier and it will turn out much better.
Yes, I don't know why I went that way :crazy: Anyway, there's always the TolexMeister just across the border :)
Its easier to obtain... some is workable but the majority just doesn't want to conform. Then the backing comes off etc etc...

But I know that because, I've tried the same.
So, is that low alcohol or no alcohol at all? mmmm, no alcohol, do you want to try it? Noooooooooo.

User avatar
Jay
Vintage Post Junkie
Vintage Post Junkie
Posts: 7761
Joined: Sat Sep 25, 2010 9:35 pm
Has liked: 1630 times
Been liked: 1297 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (MORE COMPLETE)

Post by Jay »

The original Jansen 4/Twelve does have a spare triode, not used for anything which seems a pity...

So finally I managed to put that triode to use and made the following changes:
  • extra gain stage using the spare triode (separate bias and gain controlled by its own potentiometer)
  • introduced more gain in the V2 section
  • put in a Master Volume pot
These changes transformed this amp into a different beast. It can now roar with the growl of a grisly bear or wail like an old woman moaning about her lost beauty :shock:

Five knobs to fiddle with :D

Five knobs - 20210223_132818.jpg
Five knobs - 20210223_132818.jpg (360.64 KiB) Viewed 3051 times
When faced with quality, I recognise it every time.

User avatar
Slowy
Vintage Post Junkie
Vintage Post Junkie
Posts: 22638
Joined: Wed Sep 09, 2009 4:13 pm
Location: Orcland
Has liked: 1011 times
Been liked: 2465 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (MORE COMPLETE)

Post by Slowy »

Jay wrote: Tue Feb 23, 2021 12:50 pm

These changes transformed this amp into a different beast. It can now roar with the growl of a grisly bear or wail like an old woman moaning about her lost beauty :shock:

Five knobs to fiddle with :D
Oh well, I still have the original.
:rofl:

Keen to hear it.

And if you're still up for a challenge, I have two other stunning amps for you to clone.
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.

User avatar
Jay
Vintage Post Junkie
Vintage Post Junkie
Posts: 7761
Joined: Sat Sep 25, 2010 9:35 pm
Has liked: 1630 times
Been liked: 1297 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (MORE COMPLETE)

Post by Jay »

Slowy wrote: Tue Feb 23, 2021 2:24 pm
Jay wrote: Tue Feb 23, 2021 12:50 pm

These changes transformed this amp into a different beast. It can now roar with the growl of a grisly bear or wail like an old woman moaning about her lost beauty :shock:

Five knobs to fiddle with :D
Oh well, I still have the original.
:rofl:

Keen to hear it.

And if you're still up for a challenge, I have two other stunning amps for you to clone.

Sure, but it should be heard with your speaker, not?

Let me know when you are free. Happy to drive your way if that is convenient.

ps1 - I had to change V1 from the AX7 to AY7 to tame the beast a bit. Before that it behaved even more brutal.


ps2 - always up to challenges, but a few too many on right now
When faced with quality, I recognise it every time.

User avatar
Olderama
Vintage Post Junkie
Vintage Post Junkie
Posts: 7007
Joined: Sun Dec 22, 2013 8:04 pm
Has liked: 971 times
Been liked: 876 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (MORE COMPLETE)

Post by Olderama »

Jay wrote: Tue Feb 23, 2021 2:38 pm
Slowy wrote: Tue Feb 23, 2021 2:24 pm
Jay wrote: Tue Feb 23, 2021 12:50 pm

These changes transformed this amp into a different beast. It can now roar with the growl of a grisly bear or wail like an old woman moaning about her lost beauty :shock:

Five knobs to fiddle with :D
Oh well, I still have the original.
:rofl:

Keen to hear it.

And if you're still up for a challenge, I have two other stunning amps for you to clone.

Sure, but it should be heard with your speaker, not?

Let me know when you are free. Happy to drive your way if that is convenient.

ps1 - I had to change V1 from the AX7 to AY7 to tame the beast a bit. Before that it behaved even more brutal.


ps2 - always up to challenges, but a few too many on right now
Lol you know your getting old when you struggle to read the PS2 :rofl:
:mental:

User avatar
bender
Darth Fader
Posts: 11838
Joined: Fri Feb 02, 2007 12:46 pm
Location: Dorkland
Has liked: 415 times
Been liked: 1010 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by bender »

Oh man, I’d be super keen on a clone of this.

User avatar
Jay
Vintage Post Junkie
Vintage Post Junkie
Posts: 7761
Joined: Sat Sep 25, 2010 9:35 pm
Has liked: 1630 times
Been liked: 1297 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Jay »

bender wrote: Tue Feb 23, 2021 4:12 pm Oh man, I’d be super keen on a clone of this.
That can be discussed, but I would like to do a couple then at least to make it more economical.

You did play the original one at the bollix which sounded superb and which then started this cloning process :D

Come and try the modded one to see if you like this variant of 3 mutations...
When faced with quality, I recognise it every time.

User avatar
Slowy
Vintage Post Junkie
Vintage Post Junkie
Posts: 22638
Joined: Wed Sep 09, 2009 4:13 pm
Location: Orcland
Has liked: 1011 times
Been liked: 2465 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Slowy »

bender wrote: Tue Feb 23, 2021 4:12 pm Oh man, I’d be super keen on a clone of this.
You need to play Optimus first.
Seriously.
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.

User avatar
StrummersOfThunder
Vintage Post Junkie
Vintage Post Junkie
Posts: 7161
Joined: Sun Jul 15, 2012 2:23 pm
Has liked: 807 times
Been liked: 1295 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by StrummersOfThunder »

Warm feelings

User avatar
Slowy
Vintage Post Junkie
Vintage Post Junkie
Posts: 22638
Joined: Wed Sep 09, 2009 4:13 pm
Location: Orcland
Has liked: 1011 times
Been liked: 2465 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Slowy »

StrummersOfThunder wrote: Tue Feb 23, 2021 5:29 pm Warm feelings
Nowhere near enough headroom for you, I reckon.
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.

User avatar
bender
Darth Fader
Posts: 11838
Joined: Fri Feb 02, 2007 12:46 pm
Location: Dorkland
Has liked: 415 times
Been liked: 1010 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by bender »

Slowy wrote: Tue Feb 23, 2021 4:35 pm
bender wrote: Tue Feb 23, 2021 4:12 pm Oh man, I’d be super keen on a clone of this.
You need to play Optimus first.
Seriously.
I have! I loved it. But it was skull crushingly loud. Also, less cloneable.

User avatar
bender
Darth Fader
Posts: 11838
Joined: Fri Feb 02, 2007 12:46 pm
Location: Dorkland
Has liked: 415 times
Been liked: 1010 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by bender »

Jay wrote: Tue Feb 23, 2021 4:30 pm
bender wrote: Tue Feb 23, 2021 4:12 pm Oh man, I’d be super keen on a clone of this.
That can be discussed, but I would like to do a couple then at least to make it more economical.

You did play the original one at the bollix which sounded superb and which then started this cloning process :D

Come and try the modded one to see if you like this variant of 3 mutations...
I’d love to!

Also, I already have a tweed style cab if one could fit nicely in that format.

User avatar
Jay
Vintage Post Junkie
Vintage Post Junkie
Posts: 7761
Joined: Sat Sep 25, 2010 9:35 pm
Has liked: 1630 times
Been liked: 1297 times

Re: Building a Jansen 4/TWELVE SPECIAL copy (COMPLETE)

Post by Jay »

Slowy wrote: Tue Feb 23, 2021 8:42 pm
StrummersOfThunder wrote: Tue Feb 23, 2021 5:29 pm Warm feelings
Nowhere near enough headroom for you, I reckon.
There's heaps for intimate settings, just 'dime' it to 11 for extra warm feelings :sarc:
When faced with quality, I recognise it every time.

Post Reply