Eko - Multitone  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Eko - Multitone  [schematic]

Postby Bononoob » 15 May 2019, 02:17

I traded and repaired a Eko Multitone a while back. Apparently it's the firt multi-effect ever.
It has Wah (called Strepitoso in italian), Treble/Bass Booster, Distortion and Repeat (percussion tremolo).
So I traced the 4 different circuits, you can find attached the schematics and some pics.
FS33805 are npn BJT with 1:C 2:B 3:E pinout. I tested one and hfe was 216. BC208 is apparently an equivalent and if i'm not mistaken 2n3904 could do the job.
4JD5E44 is a UJT (maybe equivalent to 2n2646 ?)
I hope I got it right the first time, but if you find anything weird on one of the circuits, point it out and I'll check the board
You do not have the required permissions to view the files attached to this post.

For this message the author Bononoob has received thanks: 12
alexradium (15 May 2019, 11:49), digi2t (15 May 2019, 03:27), fuzzbunny (15 May 2019, 06:14), Intripped (15 May 2019, 15:57), karul (18 May 2019, 17:52), Manfred (15 May 2019, 03:10), modman (15 May 2019, 08:33), rockola (15 May 2019, 13:44), toneman (15 May 2019, 05:23), Zokk (15 May 2019, 22:17) and 2 more users
Bononoob
 
Posts: 4
Joined: 28 Jun 2017, 02:45
Has thanked: 2 times
Have thanks: 18 times

Re: Eko - Multitone

Postby rockola » 15 May 2019, 13:48

Bononoob wrote:It has Wah (called Strepitoso in italian)

Eko gear has the best labels. I have an Eko Duke combo where the power switch is labeled SI/NO, inputs INGRESSI, and the tone controls ALTI and MEDI-BASSI :D
rockola
 
Posts: 4
Joined: 09 Oct 2014, 11:33
Has thanked: 9 times
Have thanks: 0 time

Re: Eko - Multitone

Postby Ben N » 15 May 2019, 18:50

rockola wrote:
Bononoob wrote:It has Wah (called Strepitoso in italian)

Eko gear has the best labels. I have an Eko Duke combo where the power switch is labeled SI/NO, inputs INGRESSI, and the tone controls ALTI and MEDI-BASSI :D

I have GOT to use this.
Ben N
Resistor Ronker
 
Posts: 308
Joined: 12 Dec 2008, 04:34
Location: Israel
Has thanked: 16 times
Have thanks: 13 times

Re: Eko - Multitone

Postby nightraven » 16 May 2019, 10:35

The first? It seems unusual for an Italian effects manufacturer to come up with something original...
Does this thing predate the Selmer Fuzz/wah/repeat? (c. 1969)
nightraven
TGP Refugee
 
Posts: 128
Joined: 21 Jul 2009, 19:38
Location: UK
Has thanked: 14 times
Have thanks: 61 times

Re: Eko - Multitone

Postby Dirk_Hendrik » 18 May 2019, 16:32

nightraven wrote:The first? It seems unusual for an Italian effects manufacturer to come up with something original...
Does this thing predate the Selmer Fuzz/wah/repeat? (c. 1969)


Careful here. Italy had a very respectable industry of electronic musical instruments in the 70's and eigthies. Especially in the synthesizer arena they did cool stuff. Think brands like Crumar and Siel. Siel was taken over by Roland for production capacitywhen they lost the battle against the DX7 (and they weren't the only one) later which resulted in some very characteristic Siel design work showing up in Roland equipment.

Which means that it's not that hard to imagine some original effects technology can originate from Italy. Or perhaps be more known under another non-italian brandname.
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

For this message the author Dirk_Hendrik has received thanks:
OC26 (21 May 2019, 10:57)
User avatar
Dirk_Hendrik
Old Solderhand
 
Posts: 4230
Joined: 03 Jul 2007, 09:44
Location: Old Amsterdam
Has thanked: 255 times
Have thanks: 1033 times

Re: Eko - Multitone

Postby idy » 20 May 2019, 18:10

Is that booster schematic right? very unusual...?

For this message the author idy has received thanks:
Bononoob (21 May 2019, 17:37)
User avatar
idy
Breadboard Brother
 
Posts: 110
Joined: 14 Dec 2011, 05:41
Location: Idyllwild, CA
Has thanked: 31 times
Have thanks: 27 times

Re: Eko - Multitone

Postby Manfred » 21 May 2019, 11:52

idy wrote:Is that booster schematic right? very unusual...?


I cannot recognize any circuit principle.
Thought to myself, who knows and ran a circuit simulation, but the circuit was not working.
I think the circuit needs a review.

For this message the author Manfred has received thanks:
Bononoob (21 May 2019, 17:37)
Manfred
Diode Debunker
 
Posts: 898
Joined: 05 Apr 2009, 00:42
Has thanked: 1028 times
Have thanks: 616 times

Re: Eko - Multitone

Postby Bononoob » 21 May 2019, 17:37

Manfred wrote:
idy wrote:Is that booster schematic right? very unusual...?


I cannot recognize any circuit principle.
Thought to myself, who knows and ran a circuit simulation, but the circuit was not working.
I think the circuit needs a review.


Oops looks like I swapped Input and Output. It makes sense if you read it the other way right ?
I corrected it, and ran it through a circuit simulation. You tell me if it still looks wrong (it's a weird boost anyway, lot of treble very quickly).
Thanks for the heads up
You do not have the required permissions to view the files attached to this post.
Bononoob
 
Posts: 4
Joined: 28 Jun 2017, 02:45
Has thanked: 2 times
Have thanks: 18 times

Re: Eko - Multitone

Postby Manfred » 22 May 2019, 13:16

The EKO booster circuit very similar to the VOX V8401 booster circuit.
I run the simulaton, using a BC183BP transistor that is a good replacement for the FS33805 transistor.
There is no significant gain, but a gain less then one namely from 0.14 to 0.91 depend on the potentiometer setting.
Thereby the input voltage was 50 Millivolts @ 1kHz.
Following the VOX booster circuity a changed the resitor values of the base voltage divider
form 22k to 220k and from 68k to 680k.
The circuit work now and have a gain form 1.4 to 8.6.
VOX_V8401toEKO_Treble-Bass_Booster.jpg
You do not have the required permissions to view the files attached to this post.

For this message the author Manfred has received thanks:
287m (22 May 2019, 14:00)
Manfred
Diode Debunker
 
Posts: 898
Joined: 05 Apr 2009, 00:42
Has thanked: 1028 times
Have thanks: 616 times


Return to Vintage Stompbox Corner ( ... - 1975)

Who is online

Users browsing this forum: crickyo and 3 guests