Spectron from Aion FX

matopotato · November 03, 2021, 05:51:50 AM

Quote from: aion on July 29, 2021, 04:59:28 PM
Quote from: idy on July 29, 2021, 01:39:04 PM
A recent thread brought up new Meatball clone, Aion's Spectron. The build doc has many interesting observations, which I thought I'd present here as of interest to all Meatball fans.

The Spectron wouldn't have been half as good if it wasn't for all the information in this thread... which, hard to believe, just turned a decade old on Tuesday. Thanks to everyone who's contributed along the way - including sharing your failures and frustration, since that's where most of the improvements come from.

I am about to build a Spectron from Aion FX and this thread is already very helpful.
I read in instructions that you can add an external trigger but then the blend will be affected. The procedure includes to cut a bridge.
Would it be possible to add and solder everything in place but leave the bridge uncut and having no impact on blend? (And of course no use of ext trigger as well)
If the answer is yes, then wouldn't it be possible to add a jumper where the bridge is. Solder the wires to the jumper pins, cut the bridge and then have a jumper to add vs remove when wanting original blend vs ext trigger? Of course only one of them at a time?

aion · November 08, 2021, 04:57:32 PM

Quote from: matopotato on November 03, 2021, 05:51:50 AM
I am about to build a Spectron from Aion FX and this thread is already very helpful.
I read in instructions that you can add an external trigger but then the blend will be affected. The procedure includes to cut a bridge.
Would it be possible to add and solder everything in place but leave the bridge uncut and having no impact on blend? (And of course no use of ext trigger as well)
If the answer is yes, then wouldn't it be possible to add a jumper where the bridge is. Solder the wires to the jumper pins, cut the bridge and then have a jumper to add vs remove when wanting original blend vs ext trigger? Of course only one of them at a time?

The Ext. Trigger mod is set up to use a switching jack, so if it's wired as in the diagram then it will be fully stock if nothing is plugged in, as though the mod was not included. So in other words, the switching jack automatically bridges the trace that was cut, but then breaks the connection if a jack is inserted.

matopotato · November 08, 2021, 06:19:08 PM

Thanks! I was unsure if the blend wet/dey functionality was lost for good. Good you cleared that out. Then installing it seems to be the obvious choice since nothing is lost as long as you are not using the ext trigger.
👍🏻

orangetones · December 03, 2021, 08:04:49 PM

Hello all!

I built the Spectron recently and am finding that I have to have the sensitivity up fully to get a decent trigger. On some settings I can't get anything going with my bass, or I have to pluck really hard.

I read this in another thread, but there as no confirmation on the outcome.

https://www.diystompboxes.com/smfforum/index.php?topic=98164.msg857563#msg857563

What are my best bets for increasing the sensitivity? The envelope triggers fine when I pluck hard, but I would like a little more sensitivity.

Using an LM358N in this build.

idy · December 03, 2021, 10:45:25 PM

Ah, the sensitivity issue. Is that a good 358 from reputable dealer or mystery IC from eBay? We all struggled so hard with 1458, some worked, others no... the 358 seemed to work... so there are a couple other things to look at:

If you have an indicator LED, is it lighting up when you play softly? (Sensitivity and Intensity on full). If it lights but no filter, then you look into your LDRs. Did you use the suggested by Aion LDRs? There is a huge range of values out there... they need to go up to a few M when dark, down into 10k or lower range when lit. If they go too low they can be padded, but that is not your problem....

So if the LEDs are just not lighting up until you play loud, you can look into this hack, biasing the opamp, the 358. Worth a try maybe...

QuoteTake a 100k pot. Attach the CW terminal terminal 3) to 9v somewhere on the board. Run a wire from the wiper to pin 3 of the 1458. There is already a 22k from pin 3 to ground (if you can find which one, you can attach your wire to the side attached to pin 3), you should see now about... less than 2v when the pot is set to CCW. As you turn it up you should approach 2v. Somewhere you will get the LED to light with no signal. (and with sensitivity maxed). You want it just below that point, so the detector is "on the edge." When (if) you get that to happen you can pick a resistor (or solder two together) to approximate that value

idy · December 03, 2021, 11:06:00 PM

I spent a few years not minding the issue because I was always using some kind of preamp boosting the guitar first. Try that and make sure that the only problem is a sticky trigger.

orangetones · December 04, 2021, 08:33:52 AM

I'll try with a boost pedal in front. This is being used with bass for me right now. I will try guitars with it today as well.

Does anyone want to chime in on the solution of the feedback resistor proposed by Mark Hammer in the link above?

Taylor · December 04, 2021, 03:00:32 PM

.

orangetones · December 04, 2021, 09:17:16 PM

I haven't had a look yet, but are the schematics the same?

orangetones · December 04, 2021, 09:21:00 PM

Just looking, and it seems the envelope follower is identical, so I guess my question relates to your board and Aion's board. They are one and the same.

Taylor · December 04, 2021, 09:32:44 PM

.

idy · December 04, 2021, 10:27:17 PM

Taylor has a point. Should be new thread.

Orange: yes they are the same circuit. But it can get confusing when someone says "R18" or "that IC up close to the power jack." And there are a few mods in the Spectron.. I think it has "Moog mod?" And expression jacks....

I don't know how to make a thread "transplant."

PRR · December 05, 2021, 01:36:38 AM

> I don't know how to make a thread "transplant."

In general: find where the thread should be split-off, hit the "Report to moderator" link at that point, and suggest a "Split Thread", maybe with a suggested new title.

orangetones · December 05, 2021, 08:36:57 AM

Quote from: orangetones on December 03, 2021, 08:04:49 PM
Hello all!

I built the Spectron recently and am finding that I have to have the sensitivity up fully to get a decent trigger. On some settings I can't get anything going with my bass, or I have to pluck really hard.

I read this in another thread, but there as no confirmation on the outcome.

https://www.diystompboxes.com/smfforum/index.php?topic=98164.msg857563#msg857563

What are my best bets for increasing the sensitivity? The envelope triggers fine when I pluck hard, but I would like a little more sensitivity.

Using an LM358N in this build.

So, I will ask this again here. Does anyone have confidence that altering the feedback resistor will solve this problem, before I go changing it out? For clarity, has anyone changed the feedback resistor on their Spectron? Or Meat Sphere? Or other envelope follower circuit?

This is suggested for a different envelope follower here as well:

https://www.freestompboxes.org/viewtopic.php?p=278844#p278844

orangetones · December 07, 2021, 07:35:51 PM

Anyone?

Why do I feel like this would get more traction in a MeatBall clone thread...

idy · December 07, 2021, 08:13:31 PM

Apparently no one has tried it, but a knowledgeable member suggested it as theoretically working. I also shared my suggestion which is known to work.

You only need to gently remove one end of the R and add a second in series (we call that a "teepee", like a little tent.)

idy · December 07, 2021, 08:17:46 PM

Also you didn't answer any of the questions put to you:
Good 358 or back-door eBay maybe-358?
Is the LED lighting when you play?
Did you use the recommended LDR?
Did you try it with a booster to confirm that it is just a sensitivity issue?

There is a process for trouble-shooting.
Voltages on the chips is often helpful.

orangetones · December 07, 2021, 11:52:19 PM

A couple different 358 chips from different sources. Tayda and some NOS chips I realized I had as well.
LED lights when triggered. But doesn't light when not triggered. Seems to work just fine when it has enough signal.
Used the recommended LDR and diffused green LED.
Works much better with a booster in front.
I can get voltages on the chip and post soon.

idy · December 08, 2021, 05:35:25 PM

Sounds good. I can attest that "biasing" the 358 solves this, and maybe changing the feedback R will do it too. I think the gain is already like... 1.8m/4.7k... = 382. I am not an engineer and would love to have someone else correct this. It is also dependent on frequency because of the caps on the "bandwidth" switch.

Are you sure the bandwidth switch is in the right position? (we have to ask dumb questions because no one knows how much you know.) One position (1/2) doesn't trigger well on low frequencies, another doesn't trigger at all.

So my experience was these things always needed a booster and sensitivity and intensity maxed to work... until I started biasing the 358.

Meatball is based on Mutron III. Mutron had a 22k R on that opamp +input to ground... but that is a "bipolar" circuit. So the analogous design choice for our "single ended" supply would be attaching that R to 4.5v. Meatball was not designed by engineers.

I don't know if that is telling you the obvious or over your head. Make sense? the easy fix is a 100k pot from +9v to pin 3. You should then be able to get it right below the point where any additional voltage will trigger it.

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Spectron from Aion FX