Sola Sound - Tonebender Mark II Professional  [schematic]

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

maybe misbiased.

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mcaviel
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Post by mcaviel »

Taller76 wrote:
phibes wrote:Son of a bitch rendered to a different folder...

Let's try again.
Now "verified" and sounding amazing...
THANKS!
:applause:
Might want to add a note about the trimmer legs...or maybe add an optional cut for e14
:thumbsup
Did the Phibes layout, i am getting really low volume, did all the cuts, which legs on the trimmer needs to be tied?
BTW, now the trimmer doesn't effect anything.

Thanks
Aviel

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johnnyg
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Post by johnnyg »

Did the Phibes layout, i am getting really low volume, did all the cuts, which legs on the trimmer needs to be tied?
I've been a little confused about fitting the trimmer as well. I've not attempted Phibe's layout yet, but I got the impression from what's been said that you could connect the outer (3rd) and middle legs together... or you could bend the outer, unused leg up out the way below the trimmer but above the board.
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Post by sonicvi »

You DO NOT want any of the trimpot legs to be connected to each other. You need to either cut off or bend up one of the legs or make a cut between them.

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Post by phibes »

As sonicvi said, it's best to knock out one of the legs as you only need to use two. You could tie the third leg in accordingly in case the trimpot fails (it probably never will) but it's kinda just extra work for nothing when fucking around with vero. You have to set it up as a variable resistor. I would draw a diagram but there are a million trimmers so I figured it would kinda be second nature to know how to adjust the trimmer your using to the layout. Always check a datasheet. If legs 1 and 3 stay connected on the same track it will obviously be rendered useless. If I'm soldering one onto Vero I won't cut any of the legs off, I'll just make a trace cut on the whichever outter leg can take the cut and then trim it shorter. The other two legs soldered in will hold the trimmer with no problem. You could also just bend one of the legs under and then make any necessary trace cuts if needed. If your building this on PCB you can either delete a pad out before etching or adjust the artwork to have lugs 1 to 2 or 2 to 3 connected. The trimmers that Dave uses have the legs spaced apart a lot wider then your standard Bournes trimmer that has the legs in the middle. If your using something along the Bournes line you'll need to bend the legs outward before pushing them through the vero.

I guess post whatever trimmer your having problems with and I'll tell you how to set it in.

As far as the low volume goes, how low is it and what kind of transistor trio are you using?
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Post by johnnyg »

That clears things up for me (new to using vero) - thanks for that sonicvi & phibes :thumbsup. I've got the same type of trimmer as used by DAM (bitsbox.co.uk sells em).

Lookin forward to building this circuit after chrimbo - have built a mkiii clone and curious how different the mkii is. Just waiting on transistors to arrive!
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Post by johnnyg »

I was just wondering if anyone has built both the DAM version and Electric Warrior's layout? I was curious how the two compare - i.e. where it's best to place the bias pot? I'm naturally assuming the DAM layout with a 100k vr in place of the 47k resistor works best - DAM being the doyen of these old British fuzzes (from what I see on the net!). It's interesting though that you are then affecting the voltage at two transistors I gather? The base of Q3 and collector of Q2?
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Post by phibes »

Putting the trimmer on Q2's Collector works the best in my opinion.
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Electric Warrior
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Post by Electric Warrior »

Seconded.

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graemey
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Post by graemey »

Built this yesterday from Phibes' layout. Wow! sounds better than my old Sola original! EVEN more gain and smoother decay (thanks to the trimmer).
Great layout, thanks!
I will post a youtube video when I get it boxed-up.

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Post by Scruffie »

Hey Graemey, Did you go for the Q2 or Q3 Trimmer pot? I'm just about to build another Tone Bender up On PCB hopefully and can't decide now.

Looking forward to your video though, keep 'em coming :D

Oh and for those interested I got another Trio of OC81Ds, they're all around the 90-100 hFe mark upon testing.

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Post by johnnyg »

As it's Phibes' layout the trimmer will be on Q2.

If you don't mind me asking Scruffie, where'd you source the OC81ds? Can't find them - other than for stupid crazy prices on ebay... got some germaniums on order from Bulgaria in right gain area I hope will do the job.
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Post by Scruffie »

My OC81Ds came from having a grandad that hoarded stuff, they were in some random PCB, dunno what it used to be but I snipped them out of that, no secret supply sadly, I see some unbranded glass OC81Ds on ebay at a reasonable cost occasionaly though but I have no idea how good they are.

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Post by johnnyg »

Ok thanks man. Those 0c81ds are a very cool find!

I have to admit I kind of like the idea of using different germaniums to what is found in these old fuzzes and seeing what sounds you get... I'm pretty certain that when they were designed it was largely a case of what was easily available at a competitive price and I'm sticking to that ethos :wink:
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Post by Scruffie »

I know, it almost feels like a waste to even put them in a pedal!

Yeah i've got a bunch of weird and wonderful germaniums that I've never heard of or know how they sound in pedals that I wanna try out, it probably was a case of grabbing what was cheap and available, i'd give the newer russian ones a go, I wanna get and try some of those myself.

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Electric Warrior
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Post by Electric Warrior »

graemey wrote:Built this yesterday from Phibes' layout. Wow! sounds better than my old Sola original! EVEN more gain and smoother decay (thanks to the trimmer).
Great layout, thanks!
I will post a youtube video when I get it boxed-up.
Sweet. I'd love to see pictures of your Sola Sound pedal...


here's an updated version of the OC81D Tone Bender layout:

Image

These seem to be the last version of the Sola Sound made Tone Benders. 50µF filter caps were used at that point.

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Post by phibes »

Cool score on the trannies Scruffie. How are they branded? I've been stocking up on em a while and really need to get off my ass and box em up. Personally, I think I like the sound with OC75's better myself.

Definitely post some pictures Graemy! Your MKi video was mucho cool.
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Post by Scruffie »

phibes wrote:Cool score on the trannies Scruffie. How are they branded? I've been stocking up on em a while and really need to get off my ass and box em up. Personally, I think I like the sound with OC75's better myself.

Definitely post some pictures Graemy! Your MKi video was mucho cool.
British Made Mullards 81Ds, I got one glass Mullard and one unbranded OC75 aswell as a metal can Mullard OC75 so i'll try them out aswell.

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Post by graemey »

Scruffie wrote:Hey Graemey, Did you go for the Q2 or Q3 Trimmer pot? I'm just about to build another Tone Bender up On PCB hopefully and can't decide now.

Looking forward to your video though, keep 'em coming :D

Oh and for those interested I got another Trio of OC81Ds, they're all around the 90-100 hFe mark upon testing.
Hi Scruffie,
It's on the base of Q3.
I knocked this one up using AC125's. The gains were around 120/130 and honestly, it just screams!
Is that a little high for Mk2 trannys?
As soon as it stops bloody snowing, I will get outside and spray an enclosure then post some pics and a video.

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Electric Warrior
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Post by Electric Warrior »

David reported even higher gains in vintage units: http://dam.10.forumer.com/viewtopic.php ... hlight=hfe

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