DIY Stompboxes => Building your own stompbox => Topic started by: analogguru on December 26, 2006, 11:30:24 AM

Title: Octavia History - Truth revealed ?
Post by: analogguru on December 26, 2006, 11:30:24 AM

Letīs start with Analog Manīs Interview with Roger Mayer (Analog Manīs Guide to Vintage Effects p. 239):

Which do you think is the version tycobrahe copied ?

Oh, I know, the one they copied, that was the one that Noel had.  ....  Jimi (Hendrix) didnīt use it on any recordings that I know of.  In the studio model that model was optimized; it could be used on 24V if you wanted to.  And the reason for that was it gave him more headroom in the actual circuit, if he needed it.  In other words, having the box designed for 24V (it would work on 9V) ......

What Analog Man didnīt ask, was:  "Roger, did you and when yes, from whom did you steel the driver-circuit ?"

Here you will find the answer:

According to:
"Helios Electronics built custom recording consoles in England from 1969 through approximately 1978…The late Richard („Dick“) Swettingham (or Swettenham?) had been the chief electronics tech at London’s Olympic Studios, where he custom built the console for Studio 1..Encouraged by the positive reactions to that desk, he founded Helios in 1969 upon being commissioned to build a desk for Olympic Studio 2, (as Helios Electronics serial #1)."

You can see a Helios console here:

The above means nothing else that chief engineer Richard Swettingham constructed many stuff before he started the Helios company. This is confirmed by the following report:
"Cyril then starts pulling out old modules A module from the FIRST Helios desk ever made I spotted - Colvin Pots - the turret board with BIG mustard caps Then - Veroboard/Stripboard, Lustraphone transformers and the inductor".

The later Helios modules were not on stripboard, they looked more like this:

or this:

And now, lets have a look at the schematics:

interesting ... it looks the same like an Octavia schematic except VT1 is drawn wrong:
2 N 3707 is a Si-NPN Transistor and not a PNP.

You can compare this with a hand-drawn schematic:

The gain Poti was a switch with resistors from 110 Ohm to 22k Ohm.

I can not really believe, that „Dirk“ Swettenham stole the circuit of „Jimiīs guitar effect unit“ to use it as an input stage in a high-end-studio-mixing-console.

So: Who stole from whom ?

what we can see is, the only secret and ingenuity lies in a transformer and two diodes to double the frequency....and this was very common at that time for frequencydoubling in radio-transmitters.

Here the transistor datas for your own personal "Roger-Mayer-Jimi-Hendrix-Octavia":
2 N 3707   30V/200mA/360mW   ß: 100 - 400/0,1mA   F<5dB   Fg: 80 MHz
2 N 4058   30V/30mA/360mW    ß: 100 - 550/0,1mA   F<5dB

Title: Re: Octavia History - Truth revealed ?
Post by: vanessa on December 26, 2006, 01:13:26 PM
This is probably a common circuit that both modified from an old Mullard spec book.
Title: Re: Octavia History - Truth revealed ?
Post by: analogmike on December 26, 2006, 01:27:48 PM
Very cool!

I always thought the 1st octavia came from Japan... check out the early superfuzz type effects. Seems more likely to me that RM heard one of these and made his own version, maybe based on that circuit above. Or did they hear Purple Haze in Japan and come up with the Japanese octave fuzz pedals  on their own just from the sound (they had no access to an octavia in Japan). Wish I had time to document some of these dates...

have fun!
Title: Re: Octavia History - Truth revealed ?
Post by: Mr.Huge on December 26, 2006, 02:37:57 PM
That's very cool info. Thanks analogguru!

I would be supprised if the first octavia was a Japanese super fuzz type pedal because Hendrix used Roger Mayer's Octavio in 1967 for Purple Haze and Fire. But hey, who knows....
-Mr. Huge
Title: Re: Octavia History - Truth revealed ?
Post by: JonFrum on December 26, 2006, 03:59:38 PM
Everyone wants to know who came first - who "invented" this or that. It comes up in music all the time. The truth is rarely as simple as "Joe Smith invented XYZ". Most ideas are in the air when they are developed, and different people are capable of putting them together on their own. Accusations of stealing are usually not particularly helpful in understanding who invented what.
Title: Re: Octavia History - Truth revealed ?
Post by: Paul Perry (Frostwave) on December 27, 2006, 03:16:56 AM
what we can see is, the only secret and ingenuity lies in a transformer and two diodes to double the frequency....

Well...... most things look 'obvious' AFTER someone has done it!!

I agree that the preamp is probably based on a 'standard' Mullard circuit of the day. Notice the three transistors are direct coupled & have a DC negative ffeedback loop to prevent thermal runaway, a holdover from the days of Ge transistors, when it would have been needed. (the AC characteristics of the amp depend on what is hung from the "feedback'" 250uF cap, for a flat response this would go to ground).
Title: Re: Octavia History - Truth revealed ?
Post by: brett on December 27, 2006, 06:49:46 AM
I've always thought that the frequency fiddling by messing with transformers (to phase split) and diodes (to rectify) looked like it came out of a 1940s or 1950s radio manual.  Perhaps the genius was in realising what it would do if applied to audio instead of radio freqs.
The driver ciruit looks like a valve analog, so it could be very old.
Title: Re: Octavia History - Truth revealed ?
Post by: Pedal love on December 27, 2006, 09:27:24 AM
The genius is how the Octavia is used. Most people in the know, talk about Octavia's in terms of the sound, complimented with other electronics. The most important thing is how the Ge diodes are matched and believe me, you could write a book about that
Title: Re: Octavia History - Truth revealed ?
Post by: analogguru on December 27, 2006, 09:40:13 AM

Maybe some people get me wrong, for this reason:

1.) RM claims, that he - as the "originator" - only knows about the real "jimi Octavia"

2.) IMHO RM seems not to be the "originator" of the driver circuit (it doesnīt matter, if it was Mullard or somebody else, even if i am interested if somebody has this mullard application)

3.) RM claims, that the unit "tyco copied" was a stage model and not optimized for 24 V.

4.) But the Tyco looks like the original 24V model

5.) When I look at the 9V RM (transformerless) Octavia and the Axis fuzz, RM made adaptions for 9V - he decreased the emitter-resistor from the first stage fromm 220k to 100k and the collector resistor from 1k to 220E, which makes sense.

6.) IMHO there has never been a 9V-(transformer)-model, because everyting derived from the 24V-circuit (Mullard or Helios, it doesnīt matter)

7.) But: If RM copied the Helios and there was a mistake in it (schematic as shown and/or assembly) RM would copy also this mistake.

8.) In the original Helios-schematic is shown a PNP-device. This would be definitely wrong, so the first thing would be to assume, that emitter and collector are misplaced, lets change it.

9.) This was in the first unit(s)

10.) I am reffering to a photo posted by Steve C in this thread: (
which looks original - and the observations of Mr. Huge in this thread: (


It will be clear, that Jimi "never used this" in the studio on 24V

11.) Maybe after short time RM found out, that it will not work properly on 24V DC and corrected this - than this will be the "studio-optimized Jimi-Octavia".

12.) Tyco copied only the wrong "copy of the Helios" and didnīt change the orientation, because it did "something" - as can be seen in the photo and schematic of the above threads.

13.) That RM found out this mistake can be seen, that in the transformerless Octavia and the axis-fuzz the first transistor is in the correct orientation.

14.) Conclusion: The real "24V-Jimi-Studio-Octavia" is the Helios-Version with an interstage-transformer and 2 diodes on the sercondary.


P.S.: Matching the diodes in IMHO is not really the problem, was done before for radios.

But, the best unit will not help you, when you cannot play like jimi - and a good guitar-player will even sound good with the worst pedal.

Title: Re: Octavia History - Truth revealed ?
Post by: analogguru on December 29, 2006, 07:22:13 AM

Ever heard of the Roger Mayer RM 68 Noise-Gates ? (

6 of them were fitted into a..... helios console:;jsessionid=ac112b791f430fe81e5619e64bebb2abf6f6a91e56a4.e3eTaxeKbh0Te38Kb3eKbxuMbNn0n6jAmljGr5XDqQLvpAe (;jsessionid=ac112b791f430fe81e5619e64bebb2abf6f6a91e56a4.e3eTaxeKbh0Te38Kb3eKbxuMbNn0n6jAmljGr5XDqQLvpAe)

And in the schematic you will find our well-known (slightly adapted) amp-circuit running on 24V: (

Here you can have a view to some inside-pictures of the RM 57 Compressor:
ftp://myspace:1234@ (http://ftp://myspace:1234@

And....if you have by chance $ 3.495,-- !!!! left in your pocket you even can buy a RM 58 Comp/Limiter: (