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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devastator
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Post by devastator »

Why using a wire with ground connection (like the one you used with your input jack ) if you not connect the ground ?

Maybe it's a stupid question but I would like to undersand, I see a lot of circuit with that way to wire the audio connections.

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Post by WhiteKeyHole »

The ground is connected, you just can't see it.

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Post by DrNomis »

Hiya Bajaman,


I built myself a Fuzz Face with a couple of Germanium transistors I got out of an old HP Electronic Counter,
the part number on the transistors were 2N2048,I measured the current gain of the two transistors,one was
about 82,I think,and the other was about 126,from memory,anyway,I put them in,set the bias up properly,
tried it out and got a nice mid gain bluesy tone out of it,which was a little bit bassy,power chords were quite
fat sounding too,especialy ones based on third intervals,deep purpleish,or ZZ Topish.

I got some pure red spray paint,primer,and spray painted the case so it had a similar colour to a Fuzz Face,
eventualy I replaced the footswitch with one of those nifty 3PDT types,and added a 3mm blue indicator
led,looks cool.

I've also built a Tonebender Mk 2 as well,I painted the case a soft silver,I ended up modding both pedals
for heaps of output level,my Tonebender deffinitely gets that Led Zeppelin tone.
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.

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Post by Scruffie »

Hey,

I just re drew Electric Warriors Tone Bender Mk II layout with bias mod (except a trimmer instead of pot) (hope your cool with this) so I could fit it in sideways into an 1590B 111x60x30 enclosure 21 Holes being the largest size that will fit in my past experience, 22 if you sand it down a bit, i've left off the pot wires as it still equates to Electric Warrior and just wondered if it looks right? Don't want to waste my only 3 Mullard OC81Ds in an incorrect build, doubt they'd survive unsoldering.
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Tone Bender Mk II 1590B Size.gif

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Electric Warrior
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Post by Electric Warrior »

2 trimmers?

get rid of VR1 and use 20k for VR2.
C6 needs to be connected to the ground trace, you got that one wrong. And you missed the trace cut between C5 and the jumper.

you could use some sockets to test you circuit without soldering in the transistors.


of course it's ok to redraw it. I don't think the arrangement of parts on a vero board is subject to copyright. The only thing that's protected is my png file.

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Post by Scruffie »

Ah cheers man, Yea I put 2 trimmers because on your layout with the Bias Pot you'd left that resistor there, should I replace VR1 with an 8k2 or just leave it out entirely.

And I would use sockets, but in England I can't find inline sockets and have to just cut 6 Pin DIP in half so that's why I need to solder them in one go. Guess I could get round it though... Sockets are useful.

Stupid hangover making me make mistakes...

Thanks for the help!

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Post by Electric Warrior »

Yes, it's meant to set the sweet spot (the voltage at c3's collector at which you think it sounds the best) at 50% of the external bias pot, so that it can compensate for higher and lower temperatures equally well. I wouldn't bother with it when using a trimmer inside the box.

It should work just right if you leave VR1 away. Its placement is seriously f***ed up, anyway ;)
and 6 pin sockets cut into pieces will work just fine.

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Post by Scruffie »

Yea I realise now my hangovers cleared up how wrong I made that... lol...

Yea it's not that they wont be fine, i''m just wondering if I can cut them into singles rather than triplets if you get me... as i'l have to for a couple of the transistor placements that aren't put together and my Dip switches don't really have a weak spot inbetween each hole.

So Just VR2, with an Jumper taking it to Q3 Collector? And no 8k2 resistor, just to make sure I get it right (it's gunna be off anyway as the resistors i'm using are some carbon comps I salvaged so will have drifted some... then bias it up to 4.5V

My brain truly isn't working today, normally i'd probably be able to work this out for myself, but as you can see, i'm not trusting my thoughts today with good reason. :slap:

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Post by Electric Warrior »

Scruffie wrote: So Just VR2, with an Jumper taking it to Q3 Collector? And no 8k2 resistor, just to make sure I get it right (it's gunna be off anyway as the resistors i'm using are some carbon comps I salvaged so will have drifted some... then bias it up to 4.5V
you'll need both jumpers.

you only seem to visit this thread when you have baaaad hangovers :D

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Post by Scruffie »

Electric Warrior wrote:
Scruffie wrote: you only seem to visit this thread when you have baaaad hangovers :D

Lol... So I do... (Yesterday started at 4 in the afternoon as a just 1 drink thing and ended up as a pub crawl going till 1 A.M with about 14 pints...) I do have hangovers alot but I think the alure of this homely pedal comforts me when I have one so I consider building it.

Oh ok, i'l leave them in, cheers man! Once again epic :slap: Oh and do I need to remove the track cut on VR2 or is that cool.

Just remembered I never gave the checked OC81D measurements either, i'l have to do that to make up for all the help you've given me.

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Post by Electric Warrior »

the track cut under VR2 is ok.

sure would be cool to have the exact measurements. thanks to you we know at least that these are not low gain..

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Post by hamster »

Scruffie wrote: but in England I can't find inline sockets
http://www.maplin.co.uk/Module.aspx?ModuleNo=5348

Image

.

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Post by Scruffie »

Shoulda said with cheap prices and postage... Yea I have seen them but too expensive for my cheap ways, I normally only order from http://www.bitsbox.co.uk Cheers anywho though! If I do order from maplin at any point or drive past one, i'l remember they do them.

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Post by Scruffie »

Oh yea with Polarity protecion with an Parrallel 1N4002 Diode... Which orientation is correct with an Positive ground pedal (I'm not loosing my Germs :( ) Is it now Anode to the -9V rail? I swear this must be somewhere and my searching skills have just been lost.

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Post by noelgrassy »

^^^^^^^scruffie, that's how I've done 4 different +gnd pedals presuming it was the only way
it could function.

NG.
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Post by noelgrassy »

^^^scruffie, that's how I've done +ground pedals presuming it was the only way
the diode would respond.

NG.
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Post by Scruffie »

noelgrassy wrote:^^^scruffie, that's how I've done +ground pedals presuming it was the only way
the diode would respond.

NG.
Cheers man :thumbsup , I shall stick that in there when I board it tommorow (the layout i've now done based on electric warriors is so horribly cramped with an couple of Carbon comps...

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Post by Scruffie »

Hoorah, with a hangover (the only time for me to work with ToneBenders...) I've finally finished my MkII with 2 OC81D and one OC81, could only bias it down to 4.6v but that's good enough (although i'm getting some reallyyy weird low background oscillation... but this may be due to my laptop), getting some really good tones out of it, used a completely different layout in the end though Electric Warrior as it didn't seem to work.

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Post by Electric Warrior »

congratulations!

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Post by Scruffie »

Thanks :thumbsup

I can also confirm that the OC71's and OC75's to me anyway, don't have the same tone as the OC81's... the 81's seem plenty gainy to me aswell yet with that smooth (yet harsh) Led Zeppelin fuzz tone, so I think I can confirm they're damn good for Tone Benders even if I stillll haven't got round to properly measuring them for gain.

The layout issue with the altered layout Electric Warrior turned out to be the crappy AC128s I was using for testing (didn't want to damage the mullards) for some reason they work fine in fuzz faces but just made white noise in this circuit, so now I just have 2 tone benders.

Also the Oscillation seemed to only occur with the 81's in a specific order, so swapped them round and now that's gone too, guess one of them is leaky and I had it in the wrong place.

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