Boss SD1 *the other bleed*

[Chaoticidal]

Hey smart people, my (Monte Allums SD808 modded) SD1 is crystal clear when switched off, but the dry signal bleeds through when switched on. It's an awesome front end boost in a high gain channel (either one of my Randalls...gain + gain  ) but I'd like the option to use it clean.

and...go

[samhay]

>I'd like the option to use it clean.
>...SD1 is crystal clear when switched off

Hi Chaoticidal. Welcome to the forum.

I think there may be a typo in your question and/or a problem with nomenclature. Can you rephrase please?

[Chaoticidal]

>I'd like the option to use it clean.
>...SD1 is crystal clear when switched off

Hi Chaoticidal. Welcome to the forum.

I think there may be a typo in your question and/or a problem with nomenclature. Can you rephrase please?

Wet does not bleed through when bypassed
Dry does bleed through when active

[samhay]

OK - that makes more sense.

It may be expected behaviour. Did it do this before you/someone did the mod's? Does it sound different to other (mod'd) SD1's?

[Chaoticidal]

I never noticed it before the mod which I did myself. In case anyone asks, tomorrow I will test to see if any settings on the pedal affect this issue.

I did the mod a year ago and never used it through a clean channel until recently. It "sounds like" the OD effect is mixing with the clean signal instead of replacing it.

[samhay]

>It "sounds like" the OD effect is mixing with the clean signal instead of replacing it.
That is how the tubescreamer and derivatives (like the SD1) work. Clipping in the feedback loop of a non-inverting op-amp stage essentially mixs the dry and clipped signals together - give this a read: http://www.geofex.com/article_folders/TStech/tsxfram.htm

I'm guessing your mod's included replacing the clipping diodes. This can change the character of the pedal and if you added LEDs, then you will get more clean(ish) headroom, which will sound like more dry signal.

[Chaoticidal]

Bam I just got slammed with some smart. I'll read that up and if there's a specific fix for it I'll post it here.

And yes, clipping diodes and such..

Thanks

[duck_arse]

more bleeding threads:

http://www.diystompboxes.com/smfforum/index.php?topic=112051.0
http://www.diystompboxes.com/smfforum/index.php?topic=101879.0

[samhay]

>more bleeding threads:

I think type of bleeding involves wet signal bleeding into the bypassed signal.

[Chaoticidal]

I just remembered that I also did a volume mod. 3 3mm LEDs were added to the clip. If I don't find my answer in that article I'll remove them and post results

[PBE6]

If you really don't like the SD-1/Tubescteamer clean+dirty mix sound, you could try converting it to a hard clipping device instead. According to the diagram on the hobby-hour website (http://www.hobby-hour.com/electronics/s/sd1-super-overdrive.php), capacitor C4 is connected between Vref and the 10k resistor following the gain stage. You can remove the diodes from the feedback loop completely and reattach them across C4 instead, making it more similar to an MXR Dist+ setup but with an SD-1 tone control and filter settings.

[slacker]

Assuming it's a standard SD-1 and you haven't converted it to true bypass then If you want to see if it really is the clean sound bleeding through then with the effect engaged turn the level all the way down, if you can still hear clean then it is bleeding through and you have a problem somewhere in the bypass path. If it goes silent then all you're hearing is the normal sound of a tube screamer, which can sound like it's mixing clean and dirty..

[Chaoticidal]

It goes silent, but it didn't sound mixed before and my screamer doesn't either.

[slacker]

Can you remember what the mods were? Was it just replacing some components with different values, nothing that altered the actual circuit.
I think Sam is probably right, some change probably to the clipping has made it sound cleaner, it would be difficult to accidentally do something to the circuit that would let clean bleed into the distorted signal.

[dschwartz]

If you're using it for boosting an amp, i totally recommend changing the diodes for leds..more volume, faster attack, and the "mixed" feel goes away

[Chaoticidal]

I already did the diode to LED mod at the same time that I did the 808 mod. It drives a gain channel beautifully but when played through a clean channel you can hear that it is literally 50-50 wet dry mix, which is fine when my gain channel is roasting it anyway, but through a clean channel it sounds like when you're mixing and you forget to turn off your direct track.

[Killthepopular]

I am using an SD1 through a clean SS amp. I've already done a bunch of mods to get more low end out of the pedal and now i want to get rid of the clean signal thing that you guys are talking about, this common characteristic of TS type pedals.

I don't necessarily want to convert it from soft to hard clipping but (from what I've read) it seems like this soft clipping circuit design of having the diodes in a feedback loop will always necessarily let through some of the dry signal, so maybe a hard clipping mod is the only way to completely remove it.

You could try converting it to a hard clipping device instead. C4 is connected between Vref and the 10k resistor following the gain stage. You can remove the diodes from the feedback loop completely and reattach them across C4 instead, making it more similar to an MXR Dist+ setup but with an SD-1 tone control and filter settings.

I would have a go at this method but, besides doing a bunch of modding already, I'm too much of a novice to know how to do this mod without a little more guidance. Would i simply remove the clipping diodes or would i also need to jumper the holes, so that the signal runs through that part of the circuit? How do i attach the diodes across c4?



Any advice on how to do this mod? Or any alternate mod ideas that might remove the clean signal? I've done a bunch of googling regarding this issue, on TSs and SD1s, and haven't really found any mods to remedy the issue.

EDIT: Like the OP I also swapped the diodes for 2 LEDs plus a jumper and now the wet/dry thing seems to have been exacerbated. I thought I'd look for a fix for the this issue first, rather than simply giving up on LEDs.

[GFR]

You can try replacing one of the diodes (on the 2 diodes side) with a jumper so that the clipping is symmetric instead of assymmetric. You may want to match the voltage drop of the two diodes left in the circuit with a multimeter.

In my experience it helps making the "mixed cleans" less evident.

[Ben N]

I am using an SD1 through a clean SS amp. I've already done a bunch of mods to get more low end out of the pedal and now i want to get rid of the clean signal thing that you guys are talking about, this common characteristic of TS type pedals.

It sounds like you really want a different pedal.

[Killthepopular]

It sounds like you really want a different pedal.

Yes, I agree, but modding is interesting and inexpensive so I want to take my current pedals as far as i can before i leap down the rabbit hole of buying more and more pedals. Who's to say that I'll find what I'm looking for in the next pedal? or the one after that? At least with Modding i'm only spending a pound or two on each set of components.

Also I've struggled to find many resources on what dirt pedals work well with clean SS amps. It seems like, 1. 99% of pedals are designed to be used in front of a broken up tube amp and 2. Most guys who own loads of pedals also mostly use tube amps so can't offer much insight on the topic.

You can try replacing one of the diodes with a jumper so that the clipping is symmetric instead of assymmetric.

Already done this. If anything the bleed is more noticeable now than ever.

Incidentally I will probably go back to silicon diodes. LEDs just seem to give you hard crunch or hard fuzz and not much else.