AXIS pot values...

[b_rogers]

ok, so i got the axis perf finished, but i only have a 10k and 2 100k's. i am going to make 47k a external pot.

i cant seem to find the explanation of the resistor trick to lower the pot values.  its a resistor across the outside lugs right?

i figured i could just use a 100k for the 47k feedback resistor and it should be ok... i am really ready to fire this thing up!

Thanks guys

Brent

[b_rogers]

ok well i guess ill just figure it out...

[brian wenz]

Hello Brent--
    Yeah, just put a 100K res. across the two outer  lugs of the 100K pot.
Brian.

[b_rogers]

thanks brian, what value do you think i should use on the 10k gain pot to get close to 2.2k?


Brent

[brett]

Use a 2.7k resistor, or maybe a 3.3k.   From memory, only lugs 2 and 3 are used.
(2.7k parallel with 10k gives a max resistance of about 2.1k, 3.3k gives 2.5k).  The resistors will make the response non-linear, but it's not usually a problem.

cheers

[b_rogers]

ok...got it running!  

man this thing has some SERIOUS fuzz and volume!  

very thick and a lot of sustain. i only have my little gem to play thru for now, but it sounds really cool.

i think im gonna take it up to a music store i go to all the time and see how it sounds thru a hiwatt i have been checking out..

overall...very JIMI..a TON of fuzz and overtones, and suprisingly quiet.

gonna hafta bust out the ultravibe and octavia tomorrow for a BOG riff fest.


thanks for the help brett and brian.
Brent

[b_rogers]

ok ive played around with this thing for an hour or so and it just rips...

like petemoore says it has that cool note event, almost synthy attack with sustain for days and tons of boost above unity..very low noise also for the amount of boost and fuzz.

very very cool fuzz..i think my modded Trippple and this are my favs.


Brent

[brian wenz]

Hello Brent--
    What mods did you do to yer Tripple??   I still haven't been able to get mine to where I like it.  I kept going over the circuit to check for any "builder errors" and couldn't find any, but it still  doesn;t sound good to me....
Hello Brett!
Thanks-
Brian.

[b_rogers]

for the triple i used the diode comp example from Joe D's site as the first stage, but with a 2.2meg from q1 collector to base and a .01uf incap.

i left out the diodes also.

there are a coupla really sweet spots on the gain dial about 1/2 way and 3/4..

i think i need to change the .1 to .01 on the axis as with my strats neck pu its a little muddy.


Brent

[brian wenz]

Hello Hello--
  By lowering the value of that 47K res. to around 15K or 20K you should be able to dial out that "woofiness" on the neck pickup.  That's one of the things that's so cool about  putting the 50K pot in there.  I had to take some time to juggle the 50K pot with the fuzz control to get a good balance of tone and gain but it seems to work pretty good.  [Keeping the volume all the way up helps, too.]
Brian.

[Doug_H]

;lkj

[petemoore]

Yupp, I just put the Axis back in a box again last week.
 [I forget why it got booted from the original enclosure..bad switch or something].
 Real fun playing Fuzz and Od And Boost type tones, gets sorta near clean guitar with guitar vol rolloff..
 Basically no doubt this is a Very Nice Fuzz Circuit..
 I can see how a 'player' could get taken in on this one over a regular FF.

[b_rogers]

ok shes all cased up in a warmer like nightingales, but i plan on taking a torch to the inside of the enclosure to turn the outside that wonderful blueish swirl like a chrome exaust pipe.

gonna do that later, and take it up the music store tomorrow afternoon to try it on a few real amps.  

RM is the man!  thanks for the youse guys..


Brent

[MartyB]

Brent, Do you have a perf layout for the RM Axis Fuzz?

MartyB

[b_rogers]

i dont have anything on the computer, but i just kinda laid it out as the schematic is. probably not the best layout but it works..


the caps that are before the fuzz and vol i just soldered them to the pot lugs.

maybe brian or doug or maybe petemoore has one?


sorry i couldnt help more

Brent

[brian wenz]

Hello Hello--
  I used the "schematic" type layout for one of mine and then used the Fuzz Central layout for another one [both on perfboard] and they both work the same.  [Pretty quiet...]
Brian.

[brett]

Hi.  Here's an alternative PCB and layout.  Note that the 1kB pot should be 2.2kB; http://members.optusnet.com.au/~jethro.dog/mypic144.jpghttp://members.optusnet.com.au/~jethro.dog/mypic145.jpg
The reason why the axis has such good noise levels is the use of 2N3904 and 2N3906 transistors, which have moderate gain and quite good noise characteristics.  I'm no EE, but this looks like a clever design.

cheers