Author Topic: Octavia Evolution courtesy of Roger Mayer  (Read 24244 times)

Ghandi

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #20 on: January 22, 2007, 08:27:41 PM »
ok analog,
seems that my axis fuzz schematic was wrong!

so to get the sound (or better sound making device) that syd barrett, marriot, framton and jimi had/used
look at point 16 and 17 in rogers history:

>16. The Octavia configuration used for the driver comprised of
>complimentary NPN PNP low noise silicon transistors driving a
>commercially obtained iron audio driver transformer. The biasing for
>these units were also varied to operate from 24V for studio work to an
>optimised version using an internal 9 Volt battery. This series of
>pedals used the type of knobs you have on your exhibit at EMP.
>17. These units were completed in early 1969 and went to guitar players
>like. Syd Barrett - Pink Floyd, Steve Marriot - Small Faces Peter
>Frampton - Small Faces. Jimi of course had some too.


take the front from the octavio where you can see the 9V changes and the right transistor in the right direction
and the back of the tyco octavia with just the transformer and the diodes, right!?

but has roger used silicon or germanium diodes?
in the octavio there are definitely silicon and even on the pics of the old tyco the diodes look like silicon.

cheers
ghandi

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #21 on: January 23, 2007, 01:11:23 AM »
johnabraham wrote:
Quote
The pivotal circuit was developed a couple of years before it's implementaion into olympic studios gear.

I do believe this, but I also believe: not from Roger Mayer...

Roger Mayer claims here:

http://www.roger-mayer.co.uk/axis.htm

Quote
The Axis Fuzz was developed in early 1967 to give an additional series of tone colours for Jimi.

and in the posting he states:

Quote
I first met Jimi on Jan 11th 1967.

and in this time Roger Mayer not even started in studio electronic developments:

Quote
After the winter 68 tour in the USA I returned to work at Olympic Studios having left the Admiralty Research Laboratories to start a new career designing and manufacturing recording studio consoles and associated outboard equipment.

This makes sense, because the chief technician Dick Swettenham had left this time olympic studios and founded the Helios company.

But this time the shown amplifiers with the pivotal circuit were still in use in the olympic console.

And I really don´t believe, that Dick Swettenham copied a fuzz-schematic to make a Mic-Amplifier out of it.

Frequency doubling with transformers and diodes for radio-frequencys was fairly common this time - if you don´t believe it, you can look through the books presented here for free:

http://www.pmillett.com/technical_books_online.htm

Do you want to know what I would like to believe ?

WARNING:
THE FOLLOWING IS A FICTIONARY FAIRY TALE AND HAS NOTHING TO DO WITH REALITY OR LIVING PEOPLE - ANYHOW, PEOPLE WITH NOT SO STRONG NERVES SHOULD NEVER READ THE FOLLOWING - THEY COULD BE IN DANGER OF A HEART ATTACK:


We are writing the year 1967, Beatles, Stones, Sex, Drugs Rock´n Roll. Love, Peace, Freedom is all around everywhere.

A young boy named Roger Rabbit is running around and wants to participate in that exciting scene.  So he is carrying equipment and visiting locations of this scene.  One day in January 67 a rory´íng friend takes Roger Rabbit to a studio named Olympic that little Roger could see, whats going on there.

At this time there was a guitarist named Jimiboy recording an album in this studio.  Sadly Roger Rabbit was male and not a "usefull" groupie - for "free love".  Jimiboy saw Roger Rabbit and was astonished, what the guy with this "uncommon" hairdress is doing here.  So he asks Roger Rabbit: "Hey, young fellow, do you have any d*pe ?".  Little Roger didn´t know, what Jimi was talking about (thinking: "d*pe, what the heck is this ?") so he answered "Sorry no, but I have a soldering iron...".  Jimiboy answered: "Fellow, I need sex, drugs and Rock´n Roll and I have my own "soldering iron" for the groupies..., so for what are you useable, hanging around here ?"

Roger Rabbit stumbled: "....ah...ah.. I....I´am a technician..."

Jimiboy said: "A technician..? F*ck off, who needs a technician now?"  But then Jimiboy had an idea:  "Ok young fellow, i will tell you something: you want to be a technician ? This guitar playing here makes me sick cause it makes my fingers wound. So if you are really a technician, then make me a unit, that I must not squeel my guitar all the time on the high E-string and destroy my finger cups with this....Go home, and if you have finished this, you have been at least good for something..."

So Roger Rabbit got a little bit nervous.  He remebered, when he build a diode-detector radio published in a thick book called "Radio Amateur´s Handbook" published by the ARRL he read that radio amateurs use frequency-doubling-stages to achieve higher frequencies.   He ran into the library and looked in this thick book, "yes here it is, and it uses ferrite cores for the transformer...very easy, one transformer, two diodes...this also should work for audio frequencies, if the core is big enough...Hey I won, with this, I can be around Jimiboy without beeing a groupie or a dr*g-d*aler".

So there was only one problem: the driver circuit.... But little Roger remembered, that the chief technician had explained him, that the big mixing console he saw in the studio uses a lot of transformers and the impedance ist about 600 Ohms. The chief technician showed him also one of the driver cards they used in the console.

Little Roger was in a hurry to finish this unit, but he remembered this cards from the mixing console.  So he went to the chief technician and asked him: "you know.... all this is very fascinating...and...you heard was Jimiboy was talking to me....".   The chief technician had a big heart and lend Roger Rabbit one of his spare modules that Roger could finish his experiments.

Yes, it worked...it really produced double frequency....Jimiboy was impressed, and Roger Rabbit was allowed to hang around further.

There was only one problem:
The recording session was finished with time, and Jimi found this little box usefull.  Roger Rabbit only had a little problem: He used the amplifier card from the mixing console, which he couldn´t take with him.

But Roger found the schematic of this amplifier card in the service department, so he drew it up, and
everything was fine...Only one little problem: the chief engineer drew in a hurry the first transistor in the wrong way...not a problem for the chief technician, cause from his mind he did it always the right way.

So little Roger was happy, that he got hold of the schematic of the driver card. He went home and tried to made copies of it... it worked somehow, but not the same way as the driver card used in the studio.

While listening to Vox Wah-Wah commercials little Roger thought: "When big Jimiboy likes such a unit, this could be a chance for me to get big into business with another guitarists".

So he produced 5 units which he sold to different musicians.  At this time there was a big PA-rental TYCON organizing the sound system for big live concerts.  One roadie saw this unit and asked the guitar player: "What the heck is this for a box?".  The guitarist said: "Little Roger assembled this usefull unit for me".  The roadie had a look inside: "Hey, f*cking sh*t, Little Roger placed the transistor in the wrong direction...".  "Ok, the rest is not so complicated, nothing really special inside...." "Let´s correct the orientation of the transistor and go into production..."

Yes, and with this words the Big TYCON stole the "intellectual property and copyright" of little Roger Rabbit.


WARNING:
THIS STORY WAS ONLY A FICTIONARY FAIRY TALE AND HAS NOTHING TO DO WITH REALITY OR LIVING PEOPLE.


@johnabraham
It seems that you have a very good contact to Roger Mayer.  Maybe you could be so kind and ask him, in which issue of the "Journal auf Audio Engineering Society" I can find the original schematic of the amplifier stage ?

analogguru
« Last Edit: January 23, 2007, 01:31:43 AM by analogguru »

petemoore

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #22 on: January 23, 2007, 01:35:04 AM »
Little Roger placed the transistor in the wrong direction...".  "Ok, the rest is not so complicated, nothing really special inside...." "Let´s correct the orientation of the transistor and go into production..."
  How does this 'compare with the schematic I built my Tycho from?
  http://www.generalguitargadgets.com/diagrams/toctsc.gif
Convention creates following, following creates convention.

Pedal love

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #23 on: January 23, 2007, 01:54:37 AM »
Quote

WARNING:
THE FOLLOWING IS A FICTIONARY FAIRY TALE AND HAS NOTHING TO DO WITH REALITY OR LIVING PEOPLE - ANYHOW, PEOPLE WITH NOT SO STRONG NERVES SHOULD NEVER READ THE FOLLOWING - THEY COULD BE IN DANGER OF A HEART ATTACK:


We are writing the year 1967, Beatles, Stones, Sex, Drugs Rock´n Roll. Love, Peace, Freedom is all around everywhere.

A young boy named Roger Rabbit is running around and wants to participate in that exciting scene.  So he is carrying equipment and visiting locations of this scene.  One day in January 67 a rory´íng friend takes Roger Rabbit to a studio named Olympic that little Roger could see, whats going on there.

At this time there was a guitarist named Jimiboy recording an album in this studio.  Sadly Roger Rabbit was male and not a "usefull" groupie - for "free love".  Jimiboy saw Roger Rabbit and was astonished, what the guy with this "uncommon" hairdress is doing here.  So he asks Roger Rabbit: "Hey, young fellow, do you have any d*pe ?".  Little Roger didn´t know, what Jimi was talking about (thinking: "d*pe, what the heck is this ?") so he answered "Sorry no, but I have a soldering iron...".  Jimiboy answered: "Fellow, I need sex, drugs and Rock´n Roll and I have my own "soldering iron" for the groupies..., so for what are you useable, hanging around here ?"

Roger Rabbit stumbled: "....ah...ah.. I....I´am a technician..."

Jimiboy said: "A technician..? F*ck off, who needs a technician now?"  But then Jimiboy had an idea:  "Ok young fellow, i will tell you something: you want to be a technician ? This guitar playing here makes me sick cause it makes my fingers wound. So if you are really a technician, then make me a unit, that I must not squeel my guitar all the time on the high E-string and destroy my finger cups with this....Go home, and if you have finished this, you have been at least good for something..."

So Roger Rabbit got a little bit nervous.  He remebered, when he build a diode-detector radio published in a thick book called "Radio Amateur´s Handbook" published by the ARRL he read that radio amateurs use frequency-doubling-stages to achieve higher frequencies.   He ran into the library and looked in this thick book, "yes here it is, and it uses ferrite cores for the transformer...very easy, one transformer, two diodes...this also should work for audio frequencies, if the core is big enough...Hey I won, with this, I can be around Jimiboy without beeing a groupie or a dr*g-d*aler".

So there was only one problem: the driver circuit.... But little Roger remembered, that the chief technician had explained him, that the big mixing console he saw in the studio uses a lot of transformers and the impedance ist about 600 Ohms. The chief technician showed him also one of the driver cards they used in the console.

Little Roger was in a hurry to finish this unit, but he remembered this cards from the mixing console.  So he went to the chief technician and asked him: "you know.... all this is very fascinating...and...you heard was Jimiboy was talking to me....".   The chief technician had a big heart and lend Roger Rabbit one of his spare modules that Roger could finish his experiments.

Yes, it worked...it really produced double frequency....Jimiboy was impressed, and Roger Rabbit was allowed to hang around further.

There was only one problem:
The recording session was finished with time, and Jimi found this little box usefull.  Roger Rabbit only had a little problem: He used the amplifier card from the mixing console, which he couldn´t take with him.

But Roger found the schematic of this amplifier card in the service department, so he drew it up, and
everything was fine...Only one little problem: the chief engineer drew in a hurry the first transistor in the wrong way...not a problem for the chief technician, cause from his mind he did it always the right way.

So little Roger was happy, that he got hold of the schematic of the driver card. He went home and tried to made copies of it... it worked somehow, but not the same way as the driver card used in the studio.

While listening to Vox Wah-Wah commercials little Roger thought: "When big Jimiboy likes such a unit, this could be a chance for me to get big into business with another guitarists".

So he produced 5 units which he sold to different musicians.  At this time there was a big PA-rental TYCON organizing the sound system for big live concerts.  One roadie saw this unit and asked the guitar player: "What the heck is this for a box?".  The guitarist said: "Little Roger assembled this usefull unit for me".  The roadie had a look inside: "Hey, f*cking sh*t, Little Roger placed the transistor in the wrong direction...".  "Ok, the rest is not so complicated, nothing really special inside...." "Let´s correct the orientation of the transistor and go into production..."

Yes, and with this words the Big TYCON stole the "intellectual property and copyright" of little Roger Rabbit.


WARNING:
THIS STORY WAS ONLY A FICTIONARY FAIRY TALE AND HAS NOTHING TO DO WITH REALITY OR LIVING PEOPLE.


 


You sir have a vivid if not disturbed imagination >:(

Arno van der Heijden

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #24 on: January 23, 2007, 05:16:07 AM »
I like your story....  :icon_mrgreen:

johnabraham

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #25 on: January 23, 2007, 05:44:18 AM »
On 11 Jan 1967 a experimental distortion in a seperate box, along with the Octavia in another box was introduced to Jimi. Work had started on this in 1966 and does not exist in any electronic manuals.

Pedal love

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #26 on: January 23, 2007, 05:49:53 AM »
Quote

So he asks Roger Rabbit: "Hey, young fellow, do you have any d*pe ?". 


 Jimiboy answered: "Fellow, I need sex, drugs and Rock´n Roll and I have my own "soldering iron" for the groupies..., so for what are you useable, hanging around here ?"

 
Hey I won, with this, I can be around Jimiboy without beeing a groupie or a dr*g-d*aler".

 


Analogguru, did you know Jimi? If you didn't, I would refrain from characterizing him in such a negative fashion. Its really irritating and Jimi is not here to defend himself.pl
« Last Edit: January 23, 2007, 05:58:42 AM by Pedal love »

Ghandi

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #27 on: January 23, 2007, 05:58:46 AM »
Conclusion: The Tyco-copy of RM´s Octavia has the first transistor the wrong way....
In the Helios schematic there are three trannys of the same type.  Mostly every technician would immediatly recognize this and nearly automatically change emitter and collector. So this can be the reason why the Tyco-copy has a wrong configuration.

The transistor orientation of the Roger Mayer Octavia as shown in the schematic is authentical (and correct).

so the tyco boys immediately saw the fault on rogers units but nevertheless copied it
and after some time roger recognized his mistake and corrected it on his units?

Is this the right conclusion of yer funny story analog?

ghandi

Arno van der Heijden

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #28 on: January 23, 2007, 06:00:33 AM »
@Pedal love: Calm down man... take it easy.....

@analogguru: Roger Mayer claims that the first Octavia unit used germanium transistors. It is quite possible that the first versions of the Helios modules where also based on germanium transistors. What do you think? Are there schematics available to prove this theory?

P.S. The Helios modules need negative supply, right?

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #29 on: January 23, 2007, 07:37:10 AM »
Sometimes i question myself, iIs reading really such a big problem ?

@Pedal Love
No I didn´t know Jimi...Did he say to you, that he knows me ?

I believe that I wrote this:

Quote
THE FOLLOWING IS A FICTIONARY FAIRY TALE AND HAS NOTHING TO DO WITH REALITY

this means my characters are in no connection with Roger Mayer, Tycobrahe or Jimi Hendrix - they are fiktiv and source only from a "vivid imagination" , maybe....This is normally the basis for every good artist.

I don´t your age, cause you keep it secret, maybe you even haven´t been born in the 60´s or 70´s.
Have you been in the 70´s in London´s Edgeware Road ? A paradise for electronicians: Miles of electronic (component) shops, one after the other....not any of the young DIY here can even imagine this, but I have seen it.
I was in the electronic and music business in the 70´s so it is also possible that this is not a "vivid or disturbed imagination", maybe it is experience - who knows ?

I would recommend, that you listen this commercial:
http://www.archerproductions.com/MP3/archive/Vox%20Wah%20Wah%20Pedal.mp3
to get an imagination of the flavour that time of "we change the world" - Bill Gates and big concerns didn´t exist so much as today.

I believe that I also wrote this for guys without nerves and/or humor:

Quote
PEOPLE WITH NOT SO STRONG NERVES SHOULD NEVER READ THE FOLLOWING - THEY COULD BE IN DANGER OF A HEART ATTACK:

Do you know the definition of a "true believer" ?
This is somebody, whos decisions have been made, and who doesn´t want to get confused by facts.


@Arno van der Heiden
Reading is really hard, eh ?
As far as I know, the first olympic modules used germanium transistors.
they were also posititive ground. Later they switched to negative ground.
A little bit more up in THIS thread you will find a link to another one:
http://www.diystompboxes.com/smfforum/index.php?topic=52731.0
in the mentioned thread you can find all the resources, schematics, pictures, everything you need.

In this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=39466.0
you can find the observations Mr. Huge et al made independently concerning the tycobrahe.


@Ghandi
Quote
so the tyco boys immediately saw the fault on rogers units but nevertheless copied it
and after some time roger recognized his mistake and corrected it on his units?

I don´t know, cause I don´t have access to the transistor markings of the tycobrahe.
In the pictures I posted, they look all the same.  Maybe RM removed the marking on the unit they got hold of and changed the orientation.  Fact is, that in the Tycho the emitter is croslinked with the collector, you can have a look for yourself. I assume, that this happened when a tyco-technician wanted to be clever.

I don´t know if he used Si or Ge-diodes, in the picture they look like Si, Mr. Huge writes 1N34A which would be germanium. Both make sense, with Ge you will get more Signal, and Si will "soften" a little bit the signal at the bottom of the wave.


@johnabraham
interesting, but this was not my question

@petermoore
I don´t know, but I don´t believe that GGG ever traced a Tycobrahe.  It seems to me more a redraw of a schematic which was circling around in the net for years.
Look at the pictures and the thread mentioned (especially what Mr. Huge observed) and make your own opinion.

analogguru





« Last Edit: January 23, 2007, 07:48:29 AM by analogguru »

Ghandi

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #30 on: January 23, 2007, 08:44:01 AM »
before I mix it up altogether:

the hand drawn helios schematic is electronically correct,
the other helios schematic is electronically incorrect,
your tyco schematic is electronically correct,
your octavio schematic is electronically correct,
way huges tyco schematic is electronically incorrect.

and way huge said that he had some original tycos under his fingers,
and always found the first transistor to be connected electronically wrong,
if  I remember correct.

do I got it right?

anyway thanks for your time and help getting more clearance in the octavio/octavia history!

cheers
ghandi

Arno van der Heijden

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #31 on: January 23, 2007, 09:22:15 AM »
@Arno van der Heiden
Reading is really hard, eh ?
As far as I know, the first olympic modules used germanium transistors.
they were also posititive ground. Later they switched to negative ground.

Maybe I should have been more clear.

What I meant to ask was: Do you know if there exist schematics of the germanium version of the Olympic module (which were possibly used as a driver for the Octavia at one time)? Or is is it just a matter of swapping silicon for germanium transistors (having the right hfe etc...)?

petemoore

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #32 on: January 23, 2007, 09:26:33 AM »
  I just would like to know what the Octavio or via has evolved to. The Tycho I have has been modified, and has to be driven hard by a Fuzz for best results.
  Mine is out of the box for repairs right now, and is going to be looked at soon.
  I'm pretty sure I turned that transistor around at least once, and decided to leave it as the schematic shows.
Convention creates following, following creates convention.

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #33 on: January 23, 2007, 09:55:36 AM »
Quote
the hand drawn helios schematic is electronically correct,

I ASSUME that the hand drawn schematic was done (traced) by a technician of Hyde-Street Studios.
Whern I look at the photos of the plug-in card the schematic SEEMS to reflect the reality.

Quote
the other helios schematic is electronically incorrect,
Definitely with 3 PNP transistors configured in this way this would be unusable in studio applications.
In a distortion-unit you can do everything, main point is that it should distort.
("Oohhhh, nice a new factory... sry, fuzz sound to play around" - yes, No. 287)

Quote
your tyco schematic is electronically correct,
My tyco schema is not 100% correct, it reflects only what I have seen from the pictures.
I can draw a perfect schematic, when i have three original units in front of me.
Then I would say: This is the way a Tyco was build.
But it SEEMS to be more correct than what was floating around previously.
And I have to say, I am only sure, that in the photo the emitter of the first transistor is connected to the base of the second one.  And I claim, that this was done intentionely.
I can NOT say if this an NPN as shown in Mr. Huges schematic, or a PNP as shown in my schematic.
A PNP would make more sense to me.

Quote
your octavio schematic is electronically correct,
The corrected octavio schematic shows what I can see from the pictures shown in this thread.
It SEEMS to me, that i reflects the reality - when I compare it also with the original RM58 and RM68 schematics. (Links to it are in the other thread).

Quote
way huges tyco schematic is electronically incorrect.
This I cannot say, outgoing from the assumtion that he has 3 original units, and I beleive that Mr. Huge is not stupid, I would say Mr. Huges schematic can be more correct than mine.

What confuses me ist the 100µF capacitor, even if he makes sense.  From the pictures above i would assume that this cap is only 25 µF, a 100µF would be bigger....

The important thing is the emitter orientation, and that is the same like in my schematic.
When you are in doubt, believe the schematic of mr. Huge.  I draw my schematic 2 years ago, without the schematic of Mr. Huge, I didn´t have time to play around with it and i didn´t want to use Mr. Huges schematic - copyright respect and so...

Quote
and way huge said that he had some original tycos under his fingers,
and always found the first transistor to be connected electronically wrong,
if  I remember correct.

When I look at the pictures , I can believe that.

Quote
do I got it right?

basically yes.

Quote
anyway thanks for your time and help getting more clearance in the octavio/octavia history!

no problem at all, "truthfinders" are alway welcome.

I am only reporting my finds and presenting my thoughts.
Please have a look at the photos and schematics and make your own opinion, and:

Never trust "authorities".

analogguru

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #34 on: January 23, 2007, 10:21:12 AM »
Quote
What I meant to ask was: Do you know if there exist schematics of the germanium version of the Olympic module (which were possibly used as a driver for the Octavia at one time)?

I was happy to find this schematics and they are rare....

What i forgot to say:
The Helios "Factory"-schematic seems to be from around 1972.
So I ASSUME that there existed an earlier hand-drawn schematic in the olympic-studio.

For one unit a hand-drawn schematic is enough, if you sell more units commercially you should be able to support the customer with "professional" schematics.

Quote
Or is is it just a matter of swapping silicon for germanium transistors (having the right hfe etc...)?
If the unit runs with germanium it should be normally no problem to swap in silicon.
silicon have less leakage current, more gain....

What confuses me a little bit on every schematic is the high input impedance.  For studio applications this gives a "not so good" noise performance and is not really necessary with input transformers as used in the mixing cxonsoles.  By using germanium transistors this can also lead you into troubles.
A rule in transistor amplifier design is, that the current through the voltage divider at the base of the transistor should be ten times higher then the collector current divided thru the gain (beta) to avoid temperature instabilities caused by the leakage current.

This is especially using germanium transistors, cause their leakager current is much higher than silicon ones - and the gain lower. So for a germanium design the very low current through the base-voltage divider would cause me real headaches.

@petermoore

I started only to report my findings on the tyco stuff. I didn´t know that this would result in a RM octavia discussion.  What I know about the RM octavia is not much, you can find pictures, schemas in this thread and referencved links. (sorry, until now I didn´t find it important enough to draw a schematic of the RM Octavia or correct the values in Justin philpots schematic - only between us my confession: I drew one of the Fifi-Factory :o. I corrected this only very rough yesterday to answer german speaking Gandhi).

analogguru
« Last Edit: January 23, 2007, 10:27:25 AM by analogguru »

Ghandi

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #35 on: January 23, 2007, 01:50:50 PM »
Quote
way huges tyco schematic is electronically incorrect.
This I cannot say, outgoing from the assumtion that he has 3 original units, and I beleive that Mr. Huge is not stupid, I would say Mr. Huges schematic can be more correct than mine.

oh no,
i although don't think that mr. huge is stupid.

what I meant was that a pnp for Q1 would make more sense than a npn on his schematic.

cheers
ghandi

petemoore

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #36 on: January 23, 2007, 02:10:38 PM »
 Octavia = Octavio
  Some schematics reflect that there are unsettled or unknowns about the circuit, or my...drift is off...
  'Will the real Slim Shady please stand up?'
  I have a Tycho-like build here and wouldn't mind seeing the circuit gone over with a fine toothed comb to see if there isn't room for improvement, trying lots of stuff, a FF with comes closest, pretty close..I have to guess.
  I was about to take the last half and see what could be done with the first half [maybe a FF w/buffer, or...] to wreak a bit more Octavio sound from it. I'm not sure what I'm getting from it alone [especially, but also w/FF] is what I want, I'm not concerned with authenticity so much as function.
Convention creates following, following creates convention.

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #37 on: January 23, 2007, 04:17:11 PM »
Quote
I'm not concerned with authenticity so much as function.

This is a reasonable word...

so I had a loook at the actual schematic at ggg.

This schematic will work fine.

1.) You can try to change C4 to 100µF this will give more bass gain/distortion at higher gain settings.

2.) Then I would place a resistor of 47 Ohm to 100 Ohm in series with the Gain poti R8.
This makes it more easy to adjust gain and secures stability. Maximum Gain will be reduced a little bit.

3.) Then you can try to change the poti R8 to 5 ok 10k (reverse) logarithmic. (reverse) logarithmic makes it more easy to adjust gain.  If you use a logarithmic for test purposes exchange the outer lugs, gain will increase counterclockwise.

depending on the value of the poti this will decrease minimum gain so you can play around with "undistorted" signals.

4.) disconnect the center tap of the output transformer and make following series setup:
+V -> 10k resistor -> Diode -> Diode -> Gnd. (Diodes 1 N 4148)
Place a 2k5 Trimmer between the connection 10k Resistor and the 2 diodes on one side and the other side to gnd (This means in parallel to both diodes).
connect the slider lug to the center tap of the output transformer.
turn the trimmer fully to gnd.

Disconnect the volume poti from the two (rectifier) diodes.
place a 10k resistor from the two (rectifier) diodes to gnd.
Place a 100nF cap between the 2 diodes/10k resistor and the volume poti.

switch the unit on and adjust the trimmer to your taste.

The purpose of this mod is to place a small dc-current through the diodes which reduces the "gating" effect when the signal gets smaller.

5.) Use 2 x 9V Batteries in series.
18 V will give you more headroom and output signal.  Maybe you can even create "transformer saturation distortion" effects.

analogguru

analogguru

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #38 on: January 23, 2007, 06:05:44 PM »

Here is a schematic about the mod I was talking:



BE WARNED !!!:

"...THIS IS MY INTELLECTUAL PROPERTY AND COPYRIGHT...."
at least for the next 20 years  ;)

analogguru

johnabraham

Re: Octavia Evolution courtesy of Roger Mayer
« Reply #39 on: January 23, 2007, 06:06:54 PM »
Pivotal circuit starting in '66.