Bass Micro Synth adjustments

Rawk Bassist · #1 05-30-2010, 05:06 PM

Recently I got an EHX Bass Microsynth pedal. It's an older one - big box, Green lettering, and detachable 24 volt wall-wart power supply. It seems to work intermittently at best. The filter-sweep sound comes through sporadically or the sound will be muffled. Pertaining to the age of these units - I suspect they work better with passive basses? I have a 5 string fretless Schecter Stiletto Studio bass. These have an 18-Volt preamp. I know you can just turn the Micro-Synth over and there's a gain adjustment pot you can access. However, I opened mine up and there are actually TWO adjustable pots. Anyone know what each does? I've used the Search function here - and there is not any info regarding the 2nd internal pot.

If anyone has any insight on using an 18 Volt active bass with this pedal, it would be greatly appreciated.

I did come across a thread where people talked about this having true-bypass or not. (or that EHX changed that factor at some point). I did note quite a bit of tone-suck. Also - the thread mentioned Analogman doing mods to this. Anyone get those done and what can/did they all do?

Rawk Bassist · #2 05-30-2010, 06:21 PM

Well I spent an hour investigating. FOR ANY OF YOU WHO HAVE THIS UNIT: The trim-pot that you can get to via the underside of the unit is the output level. The all-important INPUT gain trim-pot is inside the unit and you have to take the back cover off. So if you have a passive bass or a high-output one like myself, this is the important adjustment to make it work correctly. ALSO - keep in mind you are adjusting from the underside of the trim-pot as well - so MORE gain/output is counter-clockwise, and LESS gain/output is clockwise. (sheesh - thanks EXH).

Hope this helps anyone who has or plans to get one of these older micro-synth pedals.

cheapbasslovin · #3 05-30-2010, 07:07 PM

My understanding (I haven't played with them extensively as I am happy with how mine sounds) is that the one you can access without removing the cover is for the input gain. This will up the output, even when bypassed, because it is active before the bypass circuitry. I am pretty confident in this one because I've messed with it on mine and juicing that pot too much caused the unit to distort (differently than it is supposed to).

I've read the other one is the control of the gate. The setting will cause the unit to cut off early in the note decay or allow the unit to decay more naturally before cutting off. I haven't played with this one much and can't confirm this is accurate.

One thing to be aware of is the setting of the trigger. If the trigger is set improperly the filter wont engage. If your stop freq is set very low and the trigger is set too low, the sound will be muffled and stay that way unless you really dig in something fierce (to trigger the sweep).

Bill Ruppert · #4 05-31-2010, 08:22 AM

To set the trimmer set the unit as seen below.
Adjust the trim pot so the sound is the same if the unit is switched on or off.
It should sound the same volume wise.
This is how the MicroSynth sounds best.
(If you want it to distort then turn it up)
Bill

kevteop · #5 05-31-2010, 09:33 AM

Quote:

Originally Posted by cheapbasslovin

My understanding (I haven't played with them extensively as I am happy with how mine sounds) is that the one you can access without removing the cover is for the input gain. This will up the output, even when bypassed, because it is active before the bypass circuitry. I am pretty confident in this one because I've messed with it on mine and juicing that pot too much caused the unit to distort (differently than it is supposed to).

You are absolutely right.

The the OP: Adjust this pot until the pedal doesn't quite distort when you play very hard on your loudest bass. This will give you the optimum adjustment from the Trigger slider.

Rawk Bassist · #6 05-31-2010, 11:33 AM

All - thanks for your advice and input. I know there's cool sounds to be made with this - just getting it set right is more complex than I thought it might be. So - that internal trim pot (that you have to take the back cover off to get to) isn't a gain adjustment? I couldn't find documentation - just electrical schematics and I couldn't tell what that 2nd pot was.

Bill - that slider setting for adjusting the trim pot - will that also be true for the older model (which I have)?

Kevteop - when I'm adjusting the trim pot so "it doesn't quite distort", should I have all the sliders down or at mid-level?

Sorry for all the questions - this just seems to be quite the fickle piece of equipment.

cheapbasslovin · #7 05-31-2010, 12:42 PM

Quote:

Originally Posted by Rawk Bassist

All - thanks for your advice and input. I know there's cool sounds to be made with this - just getting it set right is more complex than I thought it might be. So - that internal trim pot (that you have to take the back cover off to get to) isn't a gain adjustment? I couldn't find documentation - just electrical schematics and I couldn't tell what that 2nd pot was.

Bill - that slider setting for adjusting the trim pot - will that also be true for the older model (which I have)?

Kevteop - when I'm adjusting the trim pot so "it doesn't quite distort", should I have all the sliders down or at mid-level?

Sorry for all the questions - this just seems to be quite the fickle piece of equipment.

No worries about the questions. It is a fickle piece of equipment. Many a folk have gotten rid of it because they couldn't wrap their head around how it worked and didn't bother asking.

The new one is true bypass, the old one is buffered bypass. On your unit the trimmer controls gain before the buffered bypass, so it will change the volume bypassed or not. The new one is true bypass so it will only change the gain on the unit when engaged.

To hear for the distortion: with the unit engaged, turn the sub octave slider all the way up, have the start and stop frequency at about half and the resonance all the way down. If you mess with the trimmer at those settings the suboctave tone will change dramatically (distort) as you get into the 'too hot' range. This pedal has some triggering/ tracking issues down below the low A. Some can get it to trigger lower, but most can get consistent triggering down to low A under the worst circumstances. Try to do your testing in the middle of your bass' range.

I haven't played with the other pot, but I read on these boards that it is a decay (maybe a noise gate) control. It kills the output when the input drops too low. This helps give the pedal the synth style decay rather than a bass guitar style decay. Hope this helps.

kevteop · #8 05-31-2010, 02:44 PM

Quote:

Originally Posted by Rawk Bassist

Kevteop - when I'm adjusting the trim pot so "it doesn't quite distort", should I have all the sliders down or at mid-level?

IIRC EHX recommend that you put the Guitar slider up full, the other three voice sliders off, the trigger slider off, and the Stop frequency slider half-way. That's how I've always set mine up anyway.

It's really not that fickle a pedal, it takes five minutes to set up and then you don't have to touch it again. The newer one is a bit more of a pain because you have to take the back off to set the preamp level (but it's not such a big deal since you should only have to do it once).

Bassnut62 · #9 06-01-2010, 12:31 AM

IMO this pedal is well worth persevering with. It is so phat, juicy and funky.....as the bishop said to the actress!

I have the old steel one too and it really was a case of set the internal pots up once and then enjoy for ever...in my case about 4 years now and i've not had to go back inside yet, despite acquiring 2 new-to-me basses since then.

Unrepresented · #10 06-01-2010, 10:05 AM

Quote:

Originally Posted by Bassnut62

IMO this pedal is well worth persevering with. It is so phat, juicy and funky.....as the bishop said to the actress!

I have the old steel one too and it really was a case of set the internal pots up once and then enjoy for ever...in my case about 4 years now and i've not had to go back inside yet, despite acquiring 2 new-to-me basses since then.

+1

Should be a set it and forget it situation.

To address an earlier question the older units had an unimpressive buffer bypass and a status light that lit on the unit being on regardless of whether the effect was active or bypassed. I had both of these issues remedied relatively inexpenively by a local pedal builder.

Bill Ruppert · #11 06-01-2010, 09:10 PM

Rawk
The Big Box version has setting just a bit different.
Below it the setting for FLAT.
Adjust the trim pot so bypassed and on are the same.
The old directions are not for a neutral or flat setting.
They were published a LONG time ago.
Bill

[quote=Rawk Bassist;9201631]

Bill - that slider setting for adjusting the trim pot - will that also be true for the older model (which I have)?