Sekova - Fuzz ( FA-II , Apollo , Crestwood )

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

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby RnFR » 10 Nov 2008, 00:14

I just made a vero layout for this pedal. of course it is not yet verified, but it looks good to me. i haven't put the values of the parts up yet, but the part numbers match AG'S schemo. if anyone builds it, make sure to let me know so we can get it up in the ready to build pages.

oh yeah, i added a power filtering cap- C11.

Image
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO
User avatar
RnFR
Old Solderhand
 
Posts: 5139
Joined: 09 Jan 2008, 07:02
Location: Inner Earth
Has thanked: 150 times
Have thanks: 174 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby analogguru » 10 Nov 2008, 01:29

Funny, on my HD I found guts where the diodes are silicon, the 27k resistors are 33k and the 5k6 resistors are 4k7. The pcb has also minor differences.
On these guts the capacitor which was in doubt is a 100n as I expected. The tantalum is a film cap.

analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
analogguru
Old Solderhand
 
Posts: 3285
Joined: 26 Jun 2007, 14:58
Has thanked: 0 time
Have thanks: 116 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby royaltoots » 10 Nov 2008, 13:46

analogguru wrote:Funny, on my HD I found guts where the diodes are silicon, the 27k resistors are 33k and the 5k6 resistors are 4k7. The pcb has also minor differences.
On these guts the capacitor which was in doubt is a 100n as I expected. The tantalum is a film cap.

analogguru


On the old DAM forum Andy/MoreCowbell posted this pic of a 9V Sekova, is it this one?

Image

more - http://dam.10.forumer.com/viewtopic.php?t=1439&highlight=sekova
User avatar
royaltoots
Breadboard Brother
 
Posts: 88
Joined: 07 Oct 2007, 18:55
Location: London
Has thanked: 2 times
Have thanks: 4 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby analogguru » 10 Nov 2008, 14:27

Yes, that´s the one.

analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
analogguru
Old Solderhand
 
Posts: 3285
Joined: 26 Jun 2007, 14:58
Has thanked: 0 time
Have thanks: 116 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby gigelmargel » 20 Jul 2009, 08:51

Hello,

I've just finished one of this using some SFT242 with gain between 70 and 90 and it sounds pretty OK, but I am not sure if it's as the original or not.

My voltages, using a 8.70 battery, are:

Q1: C = -5.75 B = -3.08 E = -2.95
Q2: C = -5.70 B = -3.03 E = -2.93

R4/R5 node: -0.06

Anyone can tell me if these voltages are OK or not?

Thx a lot !

For this message the author gigelmargel has received thanks:
modman (05 May 2015, 08:24)
gigelmargel
Resistor Ronker
 
Posts: 260
Joined: 16 Jul 2007, 21:57
Has thanked: 17 times
Have thanks: 15 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby RnFR » 22 Jul 2009, 14:45

i've got a silicon version of this on the breadboard now. i made some mods including an extra booster stage for more volume, diode switch, and i adjusted the bias a bit. later today i'll try to make it stock, pop in some Ge's, and test the voltages for you.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO
User avatar
RnFR
Old Solderhand
 
Posts: 5139
Joined: 09 Jan 2008, 07:02
Location: Inner Earth
Has thanked: 150 times
Have thanks: 174 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby gigelmargel » 23 Jul 2009, 16:36

RnFR wrote:i've got a silicon version of this on the breadboard now. i made some mods including an extra booster stage for more volume, diode switch, and i adjusted the bias a bit. later today i'll try to make it stock, pop in some Ge's, and test the voltages for you.


Thx a lot RnFR!
What silicon transistors did you use?
gigelmargel
Resistor Ronker
 
Posts: 260
Joined: 16 Jul 2007, 21:57
Has thanked: 17 times
Have thanks: 15 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby RnFR » 23 Jul 2009, 21:23

i used a 2n5087 into a 2n2907, but that's pretty much because i was set up for PNP because i tried it first with Ge transistors. i personally like this circuit better with silicon. you could try an NPN version with an 2n5088 into a 2n222 and it would probably be close. i messed with R6 a bit, too. i think i changed it to 3K9 or 4K7. that took care of any gating that was happening. i added a simple Ge booster after the tone section, and pregain control at the front of the circuit as well. now it's plenty loud, there is a tone control, and a gain control as well as an on/off/on diode switch. much more versatile and usable in my opinion. i heard this pedal at midwest buy and sell here in chicago years ago and always kicked myself for not buying it. it does a great swarm of bees kind of tone. :mrgreen:

i'll try to get those voltages measured tonight, but i think the difference in our Ge transistors used will affect the readings. do you have some silicons like i mentioned above? that would probably solidify it a bit.

i'll try and get a schematic of what i did drawn up one of these days, too.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO
User avatar
RnFR
Old Solderhand
 
Posts: 5139
Joined: 09 Jan 2008, 07:02
Location: Inner Earth
Has thanked: 150 times
Have thanks: 174 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby gigelmargel » 23 Jul 2009, 21:38

RnFR wrote:i used a 2n5087 into a 2n2907, but that's pretty much because i was set up for PNP because i tried it first with Ge transistors. i personally like this circuit better with silicon. you could try an NPN version with an 2n5088 into a 2n222 and it would probably be close. i messed with R6 a bit, too. i think i changed it to 3K9 or 4K7. that took care of any gating that was happening. i added a simple Ge booster after the tone section, and pregain control at the front of the circuit as well. now it's plenty loud, there is a tone control, and a gain control as well as an on/off/on diode switch. much more versatile and usable in my opinion. i heard this pedal at midwest buy and sell here in chicago years ago and always kicked myself for not buying it. it does a great swarm of bees kind of tone. :mrgreen:

i'll try to get those voltages measured tonight, but i think the difference in our Ge transistors used will affect the readings. do you have some silicons like i mentioned above? that would probably solidify it a bit.

i'll try and get a schematic of what i did drawn up one of these days, too.


Thx a lot RnFR!

2N5087 it's impossible to find here, but I have some BC560 (or something like that)...booster I will not add because I used booster almost all the time, so that's not a big problem.
gigelmargel
Resistor Ronker
 
Posts: 260
Joined: 16 Jul 2007, 21:57
Has thanked: 17 times
Have thanks: 15 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby gigelmargel » 25 Jul 2009, 20:35

I replaced Q1 with a BC560, Q2 with a 2N2905 and the germanium diodes with silicon ones and it sounds better.
I will try in the next days to tweak it a little.

Thx a lot RnFR again for your advices!
gigelmargel
Resistor Ronker
 
Posts: 260
Joined: 16 Jul 2007, 21:57
Has thanked: 17 times
Have thanks: 15 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby RnFR » 04 Aug 2009, 20:08

gigelmargel wrote:I replaced Q1 with a BC560, Q2 with a 2N2905 and the germanium diodes with silicon ones and it sounds better.
I will try in the next days to tweak it a little.

Thx a lot RnFR again for your advices!



you are very welcome! sorry i didn't get around to posting those voltages. try lowering the 5K6 collector resistors a bit. this helped get rid of some gating that i was hearing at the very final end of the decay. you might not be able to hear it with the diodes clipping, but without them it is very noticable.

also, i put a schematic up in the Ready To Build section with all of the mods i've done.

viewtopic.php?f=13&t=6885
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO

For this message the author RnFR has received thanks:
modman (05 May 2015, 08:25)
User avatar
RnFR
Old Solderhand
 
Posts: 5139
Joined: 09 Jan 2008, 07:02
Location: Inner Earth
Has thanked: 150 times
Have thanks: 174 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby gigelmargel » 12 Aug 2009, 12:30

RnFR wrote:
gigelmargel wrote:I replaced Q1 with a BC560, Q2 with a 2N2905 and the germanium diodes with silicon ones and it sounds better.
I will try in the next days to tweak it a little.

Thx a lot RnFR again for your advices!



you are very welcome! sorry i didn't get around to posting those voltages. try lowering the 5K6 collector resistors a bit. this helped get rid of some gating that i was hearing at the very final end of the decay. you might not be able to hear it with the diodes clipping, but without them it is very noticable.

also, i put a schematic up in the Ready To Build section with all of the mods i've done.

http://freestompboxes.org/viewtopic.php?f=13&t=6885


Thx a lot again! You're great man !
gigelmargel
Resistor Ronker
 
Posts: 260
Joined: 16 Jul 2007, 21:57
Has thanked: 17 times
Have thanks: 15 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby LucifersTrip » 24 Aug 2012, 10:25

sorry to dig up an old thread, but there was a question about whether it gates (yes)...the answer to the the low output volume was obvious (yes).

there's one on eBay now with a sound file:

http://thenoir.net/pedal-samples/sekova-faII-01.mp3

...of course, the gating could also simply be from degenerated / misbiased transistors...

For this message the author LucifersTrip has received thanks:
jrod (24 Aug 2012, 14:32)
User avatar
LucifersTrip
Resistor Ronker
 
Posts: 416
Joined: 06 Aug 2010, 11:39
Has thanked: 21 times
Have thanks: 85 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby edkoppel » 29 Aug 2012, 15:26

I would say that is a pretty accurate audio clip.

not sure if it's anything you guys don't already have, but I did a blog post on a Sekova a few months back:
http://tonemachines.blogspot.com/2011/1 ... -1969.html

the strange thing is that is sounds extremely similar to the fuzz-side of the 6-tranny Shin Ei Fuzz Wahs, but doesn't seem to be related circuit-wise at all?
:hmmm:
Tone Machines: vintage effects blog:
http://tonemachines.blogspot.com/
edkoppel
 
Posts: 25
Joined: 15 Jun 2011, 18:32
Has thanked: 1 time
Have thanks: 26 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby GodSaveMetal » 05 May 2015, 01:19

analogguru wrote:Ok, then here is the final
Sekova Fuzz (FA-II) schematic

Circuit and frequency-plot discussion follows later when I find some time.

analogguru

Please man can you repsot the circuit of the versions of SEKOVA FUZZ? great man!!!
GodSaveMetal
Resistor Ronker
 
Posts: 301
Joined: 19 Sep 2009, 17:11
Has thanked: 141 times
Have thanks: 53 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby d312a » 05 Jul 2015, 09:32

I found this schematic
Image

Some values in the tone section is incorrect:
1nF shold be 2,2nF
1uF should be 100nF
1,2 should be 220nF

I have built several variants of this circuit and IMHO it sounds better without the diodes.
I also increased the volume pot 500kB to increase the output level.

Cheers
d312a
 
Posts: 12
Joined: 01 Jun 2014, 12:00
Has thanked: 68 times
Have thanks: 9 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby d312a » 05 Jul 2015, 09:35

Ooops, don't know how to ad images or edit post to the forum so here is the link to the schematic

https://78462f86-a-87c6d4c2-s-sites.goo ... edirects=0
d312a
 
Posts: 12
Joined: 01 Jun 2014, 12:00
Has thanked: 68 times
Have thanks: 9 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby GodSaveMetal » 05 Jul 2015, 14:25

d312a wrote:Ooops, don't know how to ad images or edit post to the forum so here is the link to the schematic

https://78462f86-a-87c6d4c2-s-sites.goo ... edirects=0

Please man you would post the lay+PCB you have build?? thanks a lot, it´s awersome you post!!!
GodSaveMetal
Resistor Ronker
 
Posts: 301
Joined: 19 Sep 2009, 17:11
Has thanked: 141 times
Have thanks: 53 times

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby dukeofearl » 16 Feb 2019, 18:25

Sorry to reactivate this very old thread! I've been searching for info on this Sekova FA-II pedal and haven't had any luck.

I'm not sure but there appear to be 3 film caps on mine. Maybe some are tantalums? One of these capacitor leads is broken. The other two look fuzzy. I was hoping to replace these but can't find values. Any suggestions?! Thanks!
You do not have the required permissions to view the files attached to this post.
dukeofearl
 
Posts: 5
Joined: 16 Feb 2019, 18:20
Has thanked: 0 time
Have thanks: 1 time

Re: Sekova - Fuzz ( FA-II , Apollo , Crestwood )

Postby dukeofearl » 16 Feb 2019, 18:27

one more pic...
You do not have the required permissions to view the files attached to this post.

For this message the author dukeofearl has received thanks:
george giblet (29 Mar 2019, 05:45)
dukeofearl
 
Posts: 5
Joined: 16 Feb 2019, 18:20
Has thanked: 0 time
Have thanks: 1 time

PreviousNext

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

Who is online

Users browsing this forum: No registered users and 4 guests