BYOC Optical Compressor- issue?

[Mick Bailey]

When you pull a Vactrol apart it's just an LED and LDR in a plastic housing. Some are moulded up, some are epoxied. When you remove the epoxy there's a standard 3mm LED in there. They're a ridiculous price for what they are. The only thing special is the LED/LDR combo are spectrally matched to improve efficiency. The LDR can have different characteristics to suit different needs.

I've used the Juan's method for years in compressors, VCFs, trems and all kinds of stuff. I've used Delrin to make little housings that look pretty, but perform no better than a heatshrunk assembly, so that's now what I use. The only application where I've found a commercial Vactrol to be better is in Mesa channel switching, and building trem pedals that can chop the signal. I've not found a standalone LDR that can turn off quickly enough (10ms or so), but that's just perhaps because component suppliers just sell pretty generic LDRs over here.

I'd prefer a slower device than the VTL5C9 to improve the flutter at high compression settings, though it's arguable that no-one would use a compressor set to the max. I'll see how the rebuilt defice turns out.

[Sea Chief]

Ok I understand- so does the compression come from it set at a very high 'blinking' rate? maybe a fluke of sorts found when trem circuits with a natural sort of slight compression/ sustain .. which tbh I only realised seems to be in evidence y'day with my DR set with 'Intensity' only slightly audible. Maybe Im talking bllx.

Im unlikely to use the compression at max ever; I dont think even a 'working' pedal theres any use for this setting- like a turbo OD pedal set at max its unuseable (unless you still have big 80s hair gurning away with an Ibanez "axe").

Btw- what might be used here: again a similar'ish often-heard clean "base sound" to the JMArr clip I posted #1 but a bit cleaner/ clearer to tell maybe. A semi-acoustic gtr however well-made surely cant sustain like this naturally, so I wonder again: comp pedal? (jump to 8.00 for eg) https://www.youtube.com/watch?v=gyWM2YSdBek

[Mick Bailey]

.... so does the compression come from it set at a very high 'blinking' rate?

The compression comes from a gain circuit that attempts to maintain a constant preset signal level. When you hit a chord the gain gets reduced (because the strings are loudest at that instant) and as the note decays the gain increases as the circuit tries to compensate. This gives the illusion of increased sustain. The Vactrol is just a means of coupling the bit that detects the signal level to the amplifier section.

You can never get longer sustian then the natural note decay.

A feature of compressors is because the gain is increased as the note decays the noise level also goes up. You can hear this in the JM clip. More sophisticated units handle this noise better.

I know what you mean about a trem giving a compression effect - it's somewhat dependant on where the picked note coincides with the trem waveform. Compressors can give a trem effect for other reasons though. Mainly if the level sensing circuit is too sensitive - it can respond to string modulation and feed this back into the gain cell in a loop. You need some kind of averaging on the signal detection to prevent this. Or a Vactrol that has some latency.

A good compressor will match the note decay to the gain increase to give a more natural sound and better 'sustain' characteristics. The attack also needs to be just right, otherwise playing can feel either too spongy or too snappy. Using a compressor takes a fair bit of experimentation and getting used to the feel and dynamics. They're often a disappointment because they don't appear to do very much when they're set up correctly, but the improvement in string response and removing annoying peaks in chord work is a blessing.

I recently did some work with a guy who thought he needed a bigger amp. While he was picking notes he had plenty of clean headroom, but was getting some clipping when he hit an open chord. The amp was plenty loud enough for picking though and he wanted to keep the same sound. I suggested he borrowed a compressor. He wasn't convinced this would make much difference but said he had a mate with one. Anyhow, this fixed his problems and he reported back that the amp actually sounded much louder than it did before and now had more than enough clean headroom.

[J M Fahey]

Problem with YT videos is that they add (a lot) of (very) cheesy compression.
And cameras too.

So you'll clearly hear compression setting in (at chord strumming, for example, too slow to react to individual string pick attack) and then releasing also in a very audible way,you hear background noise fading up, in most any YT video, even if it's about a plain acoustic huitar picked up by camera microphone, no special electroniocs involved.

It's just the nature of the beast

So you can't use YT as more than a very rough idea of a sound.

Just yesterday I got into a gearpage thread by a guy using an SS Digital Markbass combo with a single 12" speaker, the combo was about 14"x14"x12"deep, plus an extension single 15"cabinet, not much larger, worried that he couldn't get the sound of the bass players at Lamb of Good and Tool (Doom bands) and asking "what pedal could he buy to get that sound" .

He linked to a YT demo by Tool's stage tech showing what they called "THE solution" , a clean boost pedal , set to 20dB boost, which he kicked in at approppriate moments in the songs.

Now 20dB is A BIIIIIIG difference .... here it was almost the same, in or out, the video showed a tiny level difference, the tone got slightly buzzier; I definitely wouldn't buy that pedal based on what could be heard.

Yet I bet live the difference must have been deafening, but none of that could be seen, among other things because of YT compression.

Even less feeling gut wrenching pressure from a 400W tube amp driving a mountain of speakers, through puny 2" plastic PC speakers.

[Sea Chief]

Well I think it sounds good with the cheeesy compression. maybe thats what I need then, a cheap cheese-compressor! ok lets say the tinny mic can et al chain is responsible mainly for the comp effect in the JM clip.. but there is a section where he transitions from one sound to the next where it sounds totally uncompressed tho, like hes going momentarily straight into amp.

Ytube cam/ PC etc compression is problematic sure- for the life of me I still cant understand the clips of some chap demo'ing a DlxReverb or a Tweed Dlx for eg, strumming away at vol 4-5 then ramped up to 9 without A) being physically uncomfortable with the massive volume eminating 3 ft away or B) how on earth any cam mic can cope without blowing up or sounding decidedly unwell itself or C) how he merely murmers -and not shouts after such deafening vol- asap after. With my DR or a 5E3 if I sit nearby, put vol to 3 I couldnt even strum a firm chord without the windows rattling or w'out it being uncomfortably loud (shame- Ive never heard my DR above 2.5). How on earth I could record it at vol 5, here, without a myriad of SM57's.. processors.. mixing desk etc to cutail the vol pressure is a perpetual mystery. I put it down to "its YTube compression" and just forget it as its a confounds me / Ive absolutely no understanding of how.