Aion Gale

[Brian S]

Anyone built one of these yet?  I finished one up last night and the pedal works but I'm not getting any noticeable difference on the threshold pot. 0 sounds the same as 10. Here's a link to the build doc. Just asking before I start looking to see if I have a problem.  Thanks.

https://aionelectronics.com/project/gale-booster-limiter/

[antonis]

It isn't very polite to make other people search for your circuit.. 

[antonis]

First step is to check for continuity between items wired with red lines..
(resistors legs may be reversed  - it doesn't actually matter as long as you locate the lower resistance path, so check it with beeper on..)



If all are OK, we'll proceed to Vactrol circuitry..

[Slowpoke101]

Just wondering if there has been any progress with this project? I am interested to see how well the limiter function works. This means I'll probably build one anyway.

[Radical CJ]

I've been having exactly the same problem described above, threshold pot does nothing. Experimenting with varying/boosting the input signal suggests that no audible compression is happening.

Done a lot of trouble shooting, testing components and contentions, etc., but I'm now at the point where I'm beginning to wonder whether the orientation of the vactrol indicated on the PCB is incorrect.

[duck_arse]

c'mon Radical, you know the drill. photos, voltages, circuits, etc.

[Radical CJ]

c'mon Radical, you know the drill. photos, voltages, circuits, etc.

In my heart I know there is nothing wrong with the PCB, its just that this one has got me feeling quite despondent. The issue must be around IC1, its passing signal and I don't see anything wrong with the voltages, but if anyone does I'd be much obliged. 

IC1 legs (supply is 9.4V)

1) 4.7V
2) 4.7V
3) 2.4V
4) 0.0V
5) 4.5V
6) 4.5V
7) 4.5V
9.1V

I'll re-flow some connections, and if I'm still stumped I'll post the humiliating photos of my messy soldering 

[duck_arse]

what diodes did you use for the bridge around the vactrol led? have you tried disconnect that led, and hook-on an external led, for to view rectifier action?

but photos.

[Rob Strand]

There's two aspects which make this a very subtle compressor:
- Once the threshold is reached the compression is quite soft.
- The maximum gain reduction  is set by the ratio R4/R3.
   If the vactrol is zero ohms the gain cannot be reduced to more than 1.
   If the vactrol is open the gain will not be more than 1 + R4/R3.

As a test you can increase R4 to say 100k.   That will give you more gain reduction and reduce the threshold.

The softness of the compression needs a different detection circuit.  That's going to change the whole concept of the circuit.

[Radical CJ]

what diodes did you use for the bridge around the vactrol led?

For the bridge I used some Small Signal Schottky Diodes labelled "BAT42", which I assume are the right type.

... have you tried disconnect that led, and hook-on an external led, for to view rectifier action?...

... As a test you can increase R4 to say 100k.   That will give you more gain reduction and reduce the threshold...

Both good ideas. I'll try them out. Many thanks.

There's two aspects which make this a very subtle compressor...

It's a funny one. The commercial product is certainly not marketed as a compressor, but as a 'magical' pre-amp. Although, as soon as I saw the schematic I thought, that's a simple/mild compressor, that could sound good between distortion and amp.

If the circuit is in fact working and the compression is just too subtle to hear, then for my purposes it would be worth switching some of the values until compression is audible. In addition to increasing the value of R4, would it be worth switching the threshold pot for a 500k?

...

but photos.

To come, I'll need to dust off and charge my camera.

[Radical CJ]

As a test you can increase R4 to say 100k.   That will give you more gain reduction and reduce the threshold.

So after trying a few of the tests suggested above it turned out that the circuit was working , but that with R4 at 15K the compression is just too subtle for the Threshold pot to make audible difference. However, it didn't need to be increased all that much to become audible, which makes me wonder whether the issue was related to some other components I used being at the extreme of their tolerances.

In the end I socketed R4 and have a 47K in their at the moment, which sounds as I imagined it should work.

Switching R4 for 100K or more allows the pedal to produce its own clipping that can be controlled with the Pre-gain. However, then the "Threshold" begins to act as a reverse volume knob in addition to increasing compression. Also the clipping isn't that beautiful.

Thanks for the help duck_arse and Rob.

(@duck_arse, I see you follow the correct variant of football, hope you're not Lion's member)

       

[duck_arse]

cheer, cheer the red and the white.

3-0. only two weeks in, 2-0. confused w/ the rugby league. Buddy running. I hope you're not a blues or pies fan.

nah, yeah, now 3 - 0. suck it up, tigers fans. buddy not running today.

[Radical CJ]

cheer, cheer the red and the white.

3-0. only two weeks in, 2-0. confused w/ the rugby league. Buddy running. I hope you're not a blues or pies fan.

nah, yeah, now 3 - 0. suck it up, tigers fans. buddy not running today.

If my girlfriend's dad asks, I'm a Bombers fan... but I was taught to kick a footy by my uncle who was Swans (although he did have a weird inclination to 1970s style drop kicks). And between us, I think we both know who is going to win on Thursday. 

[duck_arse]

nothing weird aboot drop kicks, plenty of them around here. well, alright, yes, weird.

I dunno how to kick. one of my favourite things is when the swans beat the bombers by one point or less. after the siren.