SoloDallas - Storm

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aionios
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Post by aionios »

The SoloDallas Storm is a pedal conversion of the audio path of the Schaffer-Vega Diversity System, a wireless guitar system from the mid-1970s that was used by stadium legends like Van Halen, KISS and AC/DC. In particular, Angus Young used it in the studio because he didn't feel like his guitar sounded right without it.

The Storm is based on a ton of research that SoloDallas did into the SVDS, picking apart the circuitry and eliminating the non-audio portions. SoloDallas has also released a full replica of the original tower which is both impressive and expensive in equal measure.

The attached schematic is for version 2 of the Storm, which was released this summer. I'm not sure what the differences were between this and v1, but compared to the earlier Schaffer Replica pedal, it replaces the compander with an optical limiter sub-circuit and adds the Limiter knob.

Really fantastic circuit, lots of warmth and squish with really high output.

Full tracing log here, including photos and more background info:
https://aionelectronics.com/blog/tracin ... las-storm/

PCB available here:
https://aionelectronics.com/project/gal ... r-limiter/
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Post by boby6kiler »

if you can do the same job with the tower it is nice :popcorn:

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Post by bajaman »

shouldn't R7 be connected after C6 not before ? :!:
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Post by EddieTavares »

It's a modified Flatline Compressor;

Image

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Post by aionios »

bajaman wrote:shouldn't R7 be connected after C6 not before ? :!:
Nope... it doesn't look quite right to me either, but it definitely does come before C6, straight off of IC1. Here is the board with components removed:

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Post by aionios »

EddieTavares wrote:It's a modified Flatline Compressor
Very similar, although SoloDallas says that they traced the optical portion from part of the original SVDS which would have been 1976. Not sure whether or how much this portion of the circuit was adapted for pedal use, but optical compressors go back to the 1950s, so I would have a hard time believing the Flatline wasn't based on something earlier (or at least collage of a few different circuits).
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Post by foxey »

it's OK?
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Post by EddieTavares »

aionios wrote:
EddieTavares wrote:It's a modified Flatline Compressor
Very similar, although SoloDallas says that they traced the optical portion from part of the original SVDS which would have been 1976. Not sure whether or how much this portion of the circuit was adapted for pedal use, but optical compressors go back to the 1950s, so I would have a hard time believing the Flatline wasn't based on something earlier (or at least collage of a few different circuits).
This one has no expander, maybe they believe that the expander portion are irrelevant to the tone.

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Post by Ben N »

If I am not mistaken, the purpose of the expander was to restore the original dynamics after compression for wireless transmission. It's not necessarily part of the "secret sauce".
BTW, the Solo Dallas account of all this makes absolutely no sense. The original product was the compander necessary for wireless; the new version is an optical limiter--both of which were (allegedly) in the original Schaffer-Diversity, but seemingly performing entirely different functions, but this is somehow an evolution?

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Post by boby6kiler »

foxey your layout look ggod to me
just some things i have see :
r20 andr19 you put a link but you don't and you can remove c1 and c5 probably
you don't have r21 so i presume your r5 is 1k
r17,c18,r18 and led is not show in the circuit just cable it outside
the name ic1 and ic2 is wrong
all the rest look ok to me
nice and compact thanks

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Post by foxey »

boby6kiler thanks.

The limiter doesn't work very well.
The noise is pretty loud, but it will be quiet when put in the case.

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Post by foxey »

Sorry if wrong.
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Post by bmxguitarsbmx »

Ben N wrote:If I am not mistaken, the purpose of the expander was to restore the original dynamics after compression for wireless transmission. It's not necessarily part of the "secret sauce".
From what I read from SoloDallas themselves is that you could control the compression, but the expansion was preset. Depending on which settings are mismatched, you would get something of the action of a transient modifier. Which to me seems promising, but is not represented in the circuit that has the commander circuitry.
Ben N wrote:BTW, the Solo Dallas account of all this makes absolutely no sense. The original product was the compander necessary for wireless; the new version is an optical limiter--both of which were (allegedly) in the original Schaffer-Diversity, but seemingly performing entirely different functions, but this is somehow an evolution?
From my reading of what Solo-Dallas wrote there is not only a commander circuit involved, but an optical limiter.

Cheers,
BMX

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Post by boby6kiler »

foxey if you try with the links in r19 and r20 just try without and tell us if it is better

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Post by boby6kiler »

foxey i think i have found your problem just reverse d2 d3 d4 d5 and it will work i suppose

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Post by foxey »

boby6kiler thanks for your advice.

This layout omits R19C1 and R20C5.
And the LED between BAT42 lights up only when playing the guitar.
It was like an LED used for clipping.
When the LED pin was reversed, it did not light up.
So I think BAT42 is in the right position.
But...
Is it correct that the LED lights only when playing the guitar?
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Post by boby6kiler »

c6 is polarized in the original

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Post by foxey »

boby6kiler

That's the case in the photo that answered bajaman,
but it's different in the aion photo and schematic.
which is correct?

https://aionelectronics.com/blog/tracin ... las-storm/

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Post by boby6kiler »

just look the photo and retrace all that what i have done and i see just little erros in the schematic

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Post by foxey »

little errors?

:slap:

:secret:

please

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