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Zero-Loss FX Loop--Installing on a Soldano SLO?

Posted: Fri Jun 12, 2015 3:29 pm
by Angle Loss
Hello all!
I've been feverishly reading this forum (lots of great info!), and just registered. I have an '03 Soldano SLO which sounds awesome, but of course I hate the loop and was looking at the Zero-Loss Loop.

Some presuppositions:
-I like my current SLO tone
-the current awkwardly placed loop *does* positively contribute to the classic SLO tone
-I will keep the original loop in its place (bypassing jacks) to keep original tone
-I do not want to move or remove the existing loop for tone reasons
-the best solution seems to be a solid state post-master fx loop
-my fx can be run pedal or line level (up to +8)
-current loop position is the problem, not current loop level
-I have searched this forum, sloclone forum, and several others

So, with that said, how would I best install it? The current fx loop jacks seem spaced too close. Any other issues to be aware of?

Thanks for your help!

Re: Zero-Loss FX Loop--Installing on a Soldano SLO?

Posted: Sat Jun 13, 2015 6:19 pm
by SDM
If you really are set on adding another loop, plan sounds OK, except ideally the loop would be PRE masters to be sure you get the right signal level to the effects and optimize signal to noise ratios overall.

So, install would be the same as for a Marshall really. Loop input would be fed from the treble pot wiper. Output of loop just feeds both masters here (by default in the design, nothing special you need to do).

If you opted to install post-masters, you'd find you'll need to set the masters at a specific setting to optimize things all around, and they'll always need to be be set very very loud. Won't have that problem doing things as per above, master settings won't matter.

If the stock SLO loop level is OK, best to order a line level version of the ZL loop. A line level loop can be quite easily turned into pedal level if need be, or even made switchable between the two.

Can't say on the jack spacing, don't know what the SLO measures. Several people have mounted the ZL loop board and jacks separately with success in other projects though (shielded wires to jacks if a longer run is needed).

Re: Zero-Loss FX Loop--Installing on a Soldano SLO?

Posted: Tue Jun 16, 2015 3:36 pm
by Angle Loss
Thanks for your help, SDM, I appreciate it.

I'm worried about the fx spillover between channels that I have now when running the loop. Clean and dirty masters at different levels cause a reverb or delay trail to crash/get suddenly loud when switching channels. Post master I wouldn't have that problem.

Would it work to install the loop post-masters and then add a global master immediately after, so I could set up channel volumes to appropriate send levels and regulate overall amp volume with a global master (like it works in Mesa Mk V)? I was thinking of disconnecting the slave out and using the knob hole for a global so I wouldn't have to modify the chassis. If I understand correctly (I'm a hobbyist only), I could use a 1M voltage divider as a Global just before the .02 cap leading into the phase inverter (assuming this schematic is correct). Am I missing anything? ... o100_2.gif

I did just order the ZL loop without jacks attached and will run flying leads to the board/jacks as you suggested.

Re: Zero-Loss FX Loop--Installing on a Soldano SLO?

Posted: Tue May 08, 2018 9:01 am
by burialcloud
Hey just found this post and hoping you see this as I have the exact same amp and issue. I have a Soldano slo clone I built. I purchased a zero loss a few years back and have never been able to get it working exactly how I need it to. I need a post master volume loop for the same reasons you mentioned.

I can run my zero loss pre master just fine, but when I move it to post master I get this annoying low freq. hum that intensifies when I turn my delay on as it amplifies the noise. I actually talked to mike Soldano about this and he confirmed that I was taking the signal at the correct spot (immediately after the ldr switches, and before the cap that heads off to the PI).

All I have in my effects loop is a strymon timeline and a vintage memory man, and they just don’t sound nearly as good as they do in my other amps with post master loops (Rivera knucklehead, sunn 300t, 5150) My install is clean and the b+ is great. I’ve been hearing people mentioning the need for a universal master after the loop in post master applications, but will that fix my hum/buzz issues? Did you run into this hum/buzz?

I also have a two channel matamp “black” and I’m sinilarly frustrated with my ZL in that amp. Basically the the same issue but even worse. That one is literally unusable post master because of how loud the buzz is, but works fine pre.

Just wondering if you ever got yours working as I’ve suffered along with the hum for a few years now and it’s driving me nuts.

Also, have you ever run into the other slo issue that really grinds my gears? The amp reverses phase between the distortion channel and the clean. So if you pair it with another amp in a stereo rig, you’ll have one channel out of phase. I talked to mike about this as well and we’re working towards a fix. Basically a phase switch right off the input that will flip the phase triggered by when I change channels.

Anyway. Hoping you might see this and wondering if you ever got the ZL working in an slo post master.