Aion Meridian guitar to bass switch

[DailyDovetails]

I'm building an Aion Meridian as one of my next builds. I'm thinking about adding some switches to make some of the settings switchable. My thoughts on mods are Install R8 and R17 to the bass spec. R8 will just adjust the range of the sustain pot and R17 appears to add a slight bit more negative feedback to IC2A. C10 and C11 appear to filter for IC2B and IC3B do I add a switch to make this adjustable for bass/guitar input or do I build it to one or the other. I would like to play mostly guitar but being able to play some bass might be nice. For C16 and C17/C23(same location) I'm thinking I make these switchable to give me a flat EQ and scooped EQ. Has anyone done anything similar with their Meridian build? Any advice/feedback is appreciated.

 

[eh là bas ma]

The bass specs are the best for both guitar and bass, in my humble opinion. To put it simply, it felt like the guitar version is only cutting off much warmth, much low frequencies in this circuit. In my experience, the difference between the two version sounds similar to turning up the Color control. The bass version feels better, with some extra warmth available, that can also be dialed down when playing guitars.

I tried the guitar specs, and it felt like the Color control had less range, much less bass frequencies, which can be also achieved with bass specs, setting Color past mid-rotation. So it felt like with bass specs, Color has more range than with guitar values...

Exciter sounds like it's affecting some mids, it's great for shaping the tone. Maybe something changes there too with bass specs, i don't remember. Exciter's range is still very effective and beautiful on guitars with bass values. I couldn't really tell the difference between both versions, if i recall correctly.

Be that as it may, i do think that an extra toggle to switch between both versions could be a nice feature, good idea !

Edit : I wouldn't bother with some EQ mods. With Color and Exciter controls, this circuit already have lots of range for tone shaping. Color can do some hi/low boost/cut, and Exciter can increase or decrease mids.

 

[DailyDovetails]

The bass specs are the best for both guitar and bass, in my humble opinion. To put it simply, it felt like the guitar version is only cutting off much warmth, much low frequencies in this circuit. In my experience, the difference between the two version sounds similar to turning up the Color control. The bass version feels better, with some extra warmth available, that can also be dialed down when playing guitars.

I tried the guitar specs, and it felt like the Color control had less range, much less bass frequencies, which can be also achieved with bass specs, setting Color past mid-rotation. So it felt like with bass specs, Color has more range than with guitar values...

Exciter sounds like it's affecting some mids, it's great for shaping the tone. Maybe something changes there too with bass specs, i don't remember. Exciter's range is still very effective and beautiful on guitars with bass values. I couldn't really tell the difference between both versions, if i recall correctly.

Be that as it may, i do think that an extra toggle to switch between both versions could be a nice feature, good idea !

I’m wondering if I should just do the switch for the caps on C16 and C17 then. I think I might like the option for the flatter EQ. If the rest ends up being a little bass heavy I think I have a few places I can trim it out.

 

[eh là bas ma]

I count 7 values that change between both version.

https://aionfx.com/app/files/docs/meridian_documentation.pdf

I would look for a big 8PDT toggle, or 2 x 4PDT to add these parts to the circuits. This way way you will have the two versions in a single box.

If you are looking to modify a Meridian, create some kind of variant, i guess you will have to experiment, find the best modifications to suit your tastes.

 

[DailyDovetails]

I count 7 values that change between both version.

https://aionfx.com/app/files/docs/meridian_documentation.pdf

I would look for a big 8PDT toggle, or 2 x 4PDT to add these parts to the circuits. This way way you will have the two versions in a single box.

If you are looking to modify a Meridian, create some kind of variant, i guess you will have to experiment, find the best modifications to suit your tastes.

I was thinking for the resistors installing them as the bass version which should just slightly adjust the gain. I’m not 100% sure what the difference in values for C10 and C11 do. If it’s significant I’m seeing possibly 1 switch there. Then C16 and C17/C23 will affect the range of the color/BMP tone control. If you look C17 and C23 are the same in the circuit just with 2 different footprints.

I guess I need to experiment a little.

 

[Feral Feline]

Here's some notes of my planned build:

MODS:
SW BETWEEN GUITAR & BASS MODES W/ ONE 4PDT ON-ON (and scrap of VERO/PERF)

Sustain modification
The compressor portion of the circuit is identical to the classic Ross / Dyna Comp circuit, except that the sustain control has more limited range in the PS-021. But, it can easily be modified to give a more Dyna- style effect. Change R8 to 27k and the Sustain pot to 500kC.

PART#	PS-021 (GUITAR)	PS-020 (BASS)	FFFX & NOTES
SUSTAIN	B1M	B1M	SUSTAIN MOD SW-A: 500k resistor across outer B1M lugs = C500k-ish
R8	560k	470k	SUSTAIN MOD SW-B: 27k (was part of “BASS” mods, above splits the diff
R17	39k	43k	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C10	33n	68n	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C11	2n2	4n7	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C16	10n	100n	4PDT MOD — SWITCH BETWEEN BOTH VALUES

MORE COMPRESSOR MODS POSSIBLE WITH LOOKING AT KEELEY 5-knobber etc… ?

SUSTAIN
EXCITER EVEN<>ODD
COLOUR
LEVEL
️ DRY LPF? BYPASS WHOLE CIRC OR JUST COMP?
SUSTAIN HI/LO
BASS<>TREBLE
BUFFER? DEADEND MOD



See DeadEndFX doc for mods:
“toggle switch switches in/out the final output buffer. Toggle up is buffer on, down is off. We included this
option to allow for more flexibility as to where in the chain you decide to run the pedal. Running it in front,
you may or may not need the buffer, but running at the end of a chain, or before a long cable run, the
buffer may come in handy. The original unit had this buffer on full time, but we decided to give you a
switched option.”
C9 100n > 220n




@eh là bas ma — the biggest toggle I know of is a 6PDT, and it's EXPENSIVE.
If going for an 8PDT, a rotary-switch would be feasible.

 

[eh là bas ma]

Change R8 to 27k and the Sustain pot to 500kC.

Understood, thanks ! Longue vie à Feral Feline !

Edit : just did this mod. I first used a 470k resistor across the outter lugs of the B1M Sustain control, and 27k at R8.

I had a little statics and scratching noises at the end of the pot's rotation. I added another 27k to the 470k and now it's almost completely fixed.
Sustain is greatly improved, great mod !

 

[DailyDovetails]

Here's some notes of my planned build:

MODS:
SW BETWEEN GUITAR & BASS MODES W/ ONE 4PDT ON-ON (and scrap of VERO/PERF)

Sustain modification
The compressor portion of the circuit is identical to the classic Ross / Dyna Comp circuit, except that the sustain control has more limited range in the PS-021. But, it can easily be modified to give a more Dyna- style effect. Change R8 to 27k and the Sustain pot to 500kC.

PART#	PS-021 (GUITAR)	PS-020 (BASS)	FFFX & NOTES
SUSTAIN	B1M	B1M	SUSTAIN MOD SW-A: 500k resistor across outer B1M lugs = C500k-ish
R8	560k	470k	SUSTAIN MOD SW-B: 27k (was part of “BASS” mods, above splits the diff
R17	39k	43k	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C10	33n	68n	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C11	2n2	4n7	4PDT MOD — SWITCH BETWEEN BOTH VALUES
C16	10n	100n	4PDT MOD — SWITCH BETWEEN BOTH VALUES

MORE COMPRESSOR MODS POSSIBLE WITH LOOKING AT KEELEY 5-knobber etc… ?

SUSTAIN
EXCITER EVEN<>ODD
COLOUR
LEVEL
️ DRY LPF? BYPASS WHOLE CIRC OR JUST COMP?
SUSTAIN HI/LO
BASS<>TREBLE
BUFFER? DEADEND MOD



See DeadEndFX doc for mods:
“toggle switch switches in/out the final output buffer. Toggle up is buffer on, down is off. We included this
option to allow for more flexibility as to where in the chain you decide to run the pedal. Running it in front,
you may or may not need the buffer, but running at the end of a chain, or before a long cable run, the
buffer may come in handy. The original unit had this buffer on full time, but we decided to give you a
switched option.”
C9 100n > 220n




@eh là bas ma — the biggest toggle I know of is a 6PDT, and it's EXPENSIVE.
If going for an 8PDT, a rotary-switch would be feasible.

Thank you for sharing your notes. I hadn’t thought about the sustain mod but that might be worth adding. Funny we came up with a similar idea on this one. The burning question tho. What are you doing with C17/C23? The dead end board looks neat I wasn’t aware of it. Maybe one day we can get a PPCB version with the mods built in Isosoles boost style.