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

PostPosted: 31 Mar 2008, 10:59
by analogguru
An interesting Apollo Fuzz up for sale:

http://cgi.ebay.com/APOLLO-PEDAL-VINTAG ... 0228514860

The intersting thing is the case looks like a Maestro Fuzztone clone - inside it doesn´t match with the Sekova´s or anything else - especiallybecause there are 2 Ge-diodes visible.

Any infos are welcome,
analogguru

Re: Apollo - Fuzz

PostPosted: 31 Mar 2008, 17:22
by MoreCowbell
2 Ge diodes, 7 electrolytics, what "looks like" 2 Ge transistors, 12 resistors, 1 film cap, 1 unidentified part (white cap transistor ?)....

It doesn't match any circuit I can think of.

The electrolytics look like new replacements.

Re: Apollo - Fuzz

PostPosted: 02 Apr 2008, 16:56
by MoreCowbell
it looks like the crestwood fuzz ...

Image

Image

Re: Apollo - Fuzz

PostPosted: 05 Nov 2008, 13:10
by royaltoots
I just got one like this that is badged Sekova in the usual chrome wedge ('cept the Sekova badge is mssing, so can't be 100% sure, but def from the same source) - Sounds nothing like a Fuzztone.
It has 2 x 2SB173 Matushita PNP germs, the white thing is a tant.
It's 9V, but slighlty different to other 9V Sekovas I've seen online. Here's another pic:

Image

More detailed pics, inc the underside of the pcb, soon.

Re: Apollo - Fuzz

PostPosted: 05 Nov 2008, 14:54
by DiscoFreq
I have a black fuzz (no brand label) like this too. I thought it was a painted Sekova, but then I got a Sekova and saw that the circuit was completely different...

Here's a picture of a "normal" Sekova:
http://filters.muziq.be/model/sekova/59

Re: Apollo - Fuzz

PostPosted: 07 Nov 2008, 11:35
by royaltoots
this post on the DAM forum has detailed pics, as well as referring back to here.

http://www.stompboxes.co.uk/forum/viewtopic.php?f=23&t=525

Re: Apollo - Fuzz

PostPosted: 07 Nov 2008, 12:26
by analogguru
the white thing is a tant.

I have seen a unit where a film cap was used instead - approx 220n from the size.

Interesting circuit - component values would be appreciated to finish the schematic. The unit appears to be produced in mid-1969.

BTW, the input jack appears to be not original.

analogguru

Re: Apollo - Fuzz

PostPosted: 07 Nov 2008, 22:27
by royaltoots
values

R1 - 27K
R2 - 100R
R3 - 15K
R4 - 5.6K
R5 - 5.6K
R6 - 27K
R7 - 5.6K
R8 - 15K
R9 - 5.6K
R10 - 22K
R11 - 22K
R12 - 68K

C1 - 10uF
C2 - 10uF
C3 - 33uF
C4 - 33uF
C5 - 10uF
C6 - 10uF
C7 - 10uF
C8 - unknown poly
C9 - unknown tant
C10 - 0.001uF

Q1, Q2 - 2SB173
D1, D2 - Ge diodes

input jack moved? yeah - input originally hardwired, as on the Fuzztone. 1969? from the caps?

Re: Apollo - Fuzz

PostPosted: 08 Nov 2008, 00:31
by analogguru
Thanks for the values.

From the size I would say that it is a 100nF which should have printed "104" or ".1" on it (in black or in silver). Maybe it is smaller thenthis would be "473" or ".047".

The tantalum is in another unit a film capacitor in the size between 220n and max. 470nF. The tantalum has color dots on the side to C8. Maybe you can identify them ? red/red/yellow would be 220n .

Still missing are the potentiometer values.

analogguru

Re: Apollo - Fuzz

PostPosted: 08 Nov 2008, 13:23
by royaltoots
Hi again

the film cap is probbaly 100nF, the printing is faint but I can now see 100 and a strange symbol which I think is a maker's mark - looks like this:
Image

tant has 2 dots only I can see - red + black

forgot the pots - they are Attack 500K Lin, Vol is switched Fuzztone type, 50K Lin

also - a drawing to clarify wiring:
Image

Re: Apollo - Fuzz

PostPosted: 08 Nov 2008, 14:34
by analogguru
the film cap is probbaly 100nF, the printing is faint but I can now see 100 and a strange symbol which I think is a maker's mark

I think this is the voltage rating: 100V
Typical markings for 100n mylar caps can be seen in the picture below.

50k for the volume pot appears to be a bit low when the attack pot is 500k :hmmm:

analogguru

Re: Apollo - Fuzz

PostPosted: 08 Nov 2008, 15:04
by royaltoots
no other visible markings on the cap, must be on the side closest to the switch...
on-off vol pot is defnitely 50K.

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 07:06
by RnFR
analogguru wrote:[quote
50k for the volume pot appears to be a bit low when the attack pot is 500k :hmmm:

analogguru

this is similar to DIY copies of the mosrite fuzzrite. the original had a 33K/350K setup.

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 11:22
by analogguru
That´s a valid argument, but it doesn´t take into account, that he tone control is completely different there.

For the interested ones I made some frequency plots, assuming the one capacitor to be 100n and the other one 220n.

If you increase the 220n to 470n only the bottom end below 40Hz becomes more flat - neglectable. black dot/red dot may also show 0.2 µF.

the freq-plots for the attack control are arranged as follows:
first-half attack pot value (from 1n cap) - second-half attack pot value (from 220n cap) - vol-pot value.

There are three sets:
500k attack-pot - 50k vol-pot
500k attack-pot - 500k vol-pot
50k attack-pot - 50k vol-pot

enjoy,
analogguru

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 11:43
by royaltoots
I don't know enough to interpret the charts, but regarding the tone control - instead of a standard treble bleed to ground, I think it pans between two caps, like the BMP (and Orpheum fuzz) tonestack - smallest one is 0.001uf and fully rotated this sounds a bit Superfuzz-bumblebee-like, but with a drop in volume as the the cap cuts most of the output to get this sound. At the opposite end of the sweep, it's al lot louder, very bassy and with all the fuzz gone.

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 13:23
by analogguru
Do the 2SB173 have a suffix (-B, -C or -D)?
And the attack control is really 500k ?

analogguru

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 17:57
by royaltoots
analogguru wrote:Do the 2SB173 have a suffix (-B, -C or -D)?
And the attack control is really 500k ?


ok - the transistsors have an A suffix in a circle a little distance away from the part number - underneath it on Q1 is the letter S in a red dot, and on Q2 an X in a red dot.
the Attack control is definitely 500k, very clearly printed.

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

PostPosted: 09 Nov 2008, 19:33
by analogguru
Ok, then here is the final
Sekova Fuzz (FA-II) schematic

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

analogguru

Re: Apollo - Fuzz

PostPosted: 09 Nov 2008, 19:43
by RnFR
analogguru wrote:That´s a valid argument, but it doesn´t take into account, that he tone control is completely different there.


well we haven't seen a schematic yet have we? :wink: ****edit*** - you beat me to it!
thanks for the plots. should be helpful for reconstructing this circuit. the 500k/500k looks like it might be a bit more useful- doesn't have such a massive mid scoop. just an initial guess though. i know my frequencies, but don't have much experience reading these charts as they pertain to stompboxes.

**edit again- looks like the 500k/500k might have more output on the scooped side as well?

and thanks for the schematic!

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

PostPosted: 09 Nov 2008, 19:49
by royaltoots
great - thanks!