Redesigning stompboxes for line use (not reamping / DI)

[Jayzon]

I have read a lot about using stompboxes for line level signals (synths for example), and how this is accomplished by toning the level down before and amping it after the effect. I was wondering however, how one would redesign the stompbox itself to work at line level.
I could not find any information on how to do this, and i think although it might not be a stompbox anymore, would be a interesting direction to explore for a lot of people. Any thoughts on this?

(I am capable of building from schematics -from stompbox to studio eq, but have no experience in designing).

[Earthscum]

if you look at a lot of designs, attenuation is just part of what ya gotta do to the circuit to make components work within their specs.

The easiest way would to just make an attenuator input (resistive divider to ground), that goes out to your effects and comes back in to another circuit and boosts the signal back to line level. If you are running mono, you could use a dual op amp and run an active attenuator on the input and a 10:1 preamp on  the output.

[Jayzon]

@Earthscum, this is exactly the opposite of what im looking for but i see now where my question is a bit misleading. Sorry for that Your answer helps me to clarify my problem though;

I am aware of how one needs to attenuate the input and boost the output to make a stompbox work for line level signals ; "to make components work within their specs".

What i want to experiment with though is to redesign a stompbox (its components) so that its components are suited for line level; and thereby provide better audio quality, s/n ration, control over distortion etc.
- there are so many great analog guitar pedals, and yet so little analog effects designed for line level use!

Perhaps this is not something that a lot of guitarists are looking for, but it could be interesting for those who would like to use analog effects with their synths or mixer.

[Earthscum]

basically it's designing the circuit to accept a 1Vp-p signal, but somewhere in the circuit the signal gets attenuated anyways. If you make one box, you can just loop all your effects at the levels they need, and the input and output basically get line level in and out.

I believe all you have to do is make custom input stages for any pedal... so basically, you are making an active attenuator. If you are doing distortion, you can just run line level through a cap with a pair of diodes to ground and then build a boost circuit afterwards to bring the signal back up to line. Don't even need a boost to get a decent overdrive sound at line level.

If you build a digital delay, some chips won't handle a large signal, so it has to be attenuated.

Fet inputs: large signals are going to clip the JFet input circuits. I've tried running 1V signal to MPF102's and still had input clipping, albeit not NEARLY as bad as the J201.

[Jayzon]

Thank you for your quick reply! To be honest, I am not sure if i understand this correctly - or what the implications of this are.
I understand that certain components in stompboxes (and indeed especially digital ones) require a certain level / or can handle a certain level without distorting. And therefor you could make a input stage that converts a given signal to a 'workable'level.
My idea however was to 'upscale'the -non input/output- components. I know this is not the right word, but perhaps my original -crude- train of thought explains it better;

If you look at high grade (studio) compressors and eq's for example, they are designed to take line level signals - and higher voltages, and therefore use specific components for this purpose.A lot of these machines (all but passive eq's?) indeed have a input- and output amp-stage as well. But if im correct these machines do their work at higher levels/voltages as well; So not just input and output but also the compressing / equalizing.

Now compare these to a eq- or compressor- pedal for example; it requires components with different characteristics (value range), both for the input/output and the 'effect part' if im correct. Of course this has something to do with size restrictions, but there are obviously also sonic differences/consequences.

Following this, i thought; could analog effects (for example a analog flanger) be redesigned/upscaled/upgraded, to work at higher levels (instead of letting it work at lower levels, by providing suitable attenuation and boosting).


-- What i take from your answer (forgive me if im wrong) is that the attenuator / boosting is always needed, as the components would otherwise distort.
My assumption was that you could use different values/materials of components (upscaling if you will) to bring the entire circuit up to linelevel / perhaps higher quality.





 

[caress]

design the circuit to run on a higher voltage/dual supply?
most synth gear runs at +/- 12 or 15v.