Xvive Vactrols from China BEWARE

[Giveusyourbones]

Well I bit it this time, I decided to buy cheap Xvive vactrols from China and save a few bucks. How wrong I was, they didn't work and it ended up costing more in the end after I had to order proper ones from small bear. I really should have known better, installing the chinese 'Xvive' in both the deadendfx turbo trem and E nigma made them partially work, the turbo trem only worked for certain wave shape settings and the time portion of the E nigma wouldn't flange properly. So to save others the self induced grief caused from being a tight wad you should avoid the following vactrols on Ebay;

https://www.ebay.ca/itm/5pcs-VTL5C3-Xvive-Audio-Opto-Coupler/392257148367?hash=item5b545915cf:g:Y0AAAOSwzMlchhaS

I tried these out in other projects I have that use opto's but they also do weird stuff, so I'd say they're complete duds. Lesson learned 

[ElectricDruid]

Yikes!

Here's what a genuine Xvive Vactrol looks like:

https://electricdruid.net/product/xvive-vtl5c3-vactrol/

BTW, Xvive is a brand of a Chinese company (Shenzhen FZone Technology Co.Ltd.), so the genuine ones come from China too. Interesting that the Chinese fakers are ripping off Chinese businesses as much as everyone else.

T.

[rankot]

In recent months (years?), I've bought a lots of different vactrols from different sources. Finally, I decided to make a vactrol tester and see what I really have at hand. Basically, I wanted to test rise/fall times, because resistance can be easily measured. So I came to this:



Simple 555 based astable multivibrator, with 1s period and short trigger pulse, so vactrol is hit with a short pulse, and then left to fall.

Those are oscillographs for the first three I tested:

#1 is Xvive VTL5C2 (green dot), bought from www.musikding.de


#2 is VTL5C2 1710 PRC (original?) I bougth recently from Aliexpress:


#3 is VTL ST, bought from Aliexpress, I have 30 of them and they were insanely cheap (and sold as VTL5C1, if I remember well)


It seems that #1 is actually very far from real VTL5C2 specs (if we look fall times), because it is very short. On the contrary, both Chinese VTLs look much closer to required fall time (500ms). I will test more soon and post my findings here. Off resistance on all three of them is more than 200M, so I couldn't measure it.

[rankot]

OK, after them, #4 tested is LCR-0202 (https://www.senbasensor.com/products/low-distortion-coupling-linear-optocoupler.html). It can be bought for cheap and is in a cute and small rectangular case.

Seems to have slow fall time as well. Off resistance is still too big to measure.

[rankot]

#5 is VTL5C3 1440 PRC (presumably original?) bought from Banzai Music:


#6 is VTL5C3 Xvive (yellowish dot) bought from Banzai Music, too:

Notice the difference between the two!

#7 is VTL5C10 1423 PRC bought from uk-electronic.de


#8 is NSL-32 bought from Banzai Music


And that's all from my collection. I do have one VTL5C9 (original), but it's already soldered to the Weak Joe compressor and I'm not in the mood to desolder it just to check it's fall time

Soon I will measure resistances at 1mA and 10mA LED current.

[rankot]

Photos of all tested vactrols for your reference:



Judging only by those fall times, VTL5C3 Xvive is very similar to LCR-0202 and VTL5C2 1710 PRC.
VTL5C3 1440 PRC (from Banzai) is very similar to NSL-32 and VTL ST is similar to them, but with slightly different resistance. I presume fall time for all those six fellas is 500ms, although VTL5C3 should have 35ms fall time.
VTL5C2 Xvive from Musicding is totally different from all the others, regarding both resistance and fall time, which is approx. 30-50ms (should be 500ms acc. to datasheet).
VTL5C10 1423 PRC seems to be original, see slow fall ramp (1.5s acc. to datasheet).

[garcho]

Quality components that are up to spec have everything to do with the seller, NOT the country of origin. If you don't trust the seller, don't buy regardless of where the manufacturer has underage slave wage labor toiling away for your convenience. If you trust the seller, Chinese components used in audio devices will be every bit as good as those made in Japan or Germany or the US. It's the owner/management of the company that is ultimately responsible for quality. Are there fake ______? Probably, but your chances of getting those as opposed to simply out-of-spec components are near zero. Selling fakes on eBay doesn't make anyone any significant money at all and most people aren't thieves anyway. Lazy redistributors of out-of-spec, passé technology? Sure. Thieves who spend time and effort making fake components to trick the random drop in the bucket DIYer who spends 10, 20 bucks a pop? No.

[rankot]

Conclusion:



I couldn't precisely measure fall time (from resistance @ 1mA to 100k) and I actually calculated this time from oscilloscope screenshots, which are very low res. But this table shows that most of these vactrols are really not so close to original Perkin Elmer / Excelitas specs. On the other side, it seems that there are some really cheap ones (LCR-0202 and VTL ST), which can be easily used in various circuits with little (if any) alterations instead of VTL5C2/4/10, for example.

If one has an idea how to precisely measure fall times, please help.

[Strategy]

I love using vactrols in stuff and will sometimes socket and even try different ones from the same batch to see what happens. But I wanted to recommend roll-your-own's for the Loveclone projects, Deadendfx or otherwise. I can't recall the exact specs recommended in the DEFX Meaty Balls build doc or Alanp's Meatball but after building Meatballs using both vactrols and my own green LED home made ones (including in a build of the musicpcb.com one) I will probably not go back to vactrols for any Lovetone build. I had an original meatball in the 1990s and only the rolled-my-own version comes close sonically.
(I have Turbotrem on the bench right now and Alanp's version of the ? flanger, and will probably make my own led/ldr combos for those too, we'll see.) It is certainly cheaper but extra legwork, but fun ---
Roll your own! 

[rankot]

I love using vactrols in stuff and will sometimes socket and even try different ones from the same batch to see what happens. But I wanted to recommend roll-your-own's for the Loveclone projects, Deadendfx or otherwise.

What kind of photoresistors do you use for that?

[Strategy]

What kind of photoresistors do you use for that?

I used 10k/1M LDRs and diffuse green LED's.

[mth5044]

Cool experiment, Rankot. Thanks for sharing!

[bushidov]

What would be a good recommendation to roll ones own VTL5C4/2 for a DOD 440 Envelope Filter clone?

I tried an XVIVE one from SmallBear. It filters, but crackles a lot. It appears to be the Vactrol as the crackle disappears when removed but I am not sure of the circuit either, so the Vactrol may be ok. I would like a test, but those Vactrols are pricey for just testing. This would be a 5pin Vactrol.

[rankot]

I used 10k/1M LDRs and diffuse green LED's.

Any specific type, or just some no names?

[garcho]

It filters, but crackles a lot.

That's probably not crackling, like what's going on in a faulty cable, but a phenomenon known as ripple. It's the bane of every amplitude envelope follower design. I seriously doubt there is anything "wrong" with your vactrols that's producing that sound. Instead of retread a well worn path here, let me just throw a couple links to further reading below.

http://www.geofex.com/article_folders/ecftech/ecftech.htm

https://www.nicolascollins.com/texts/electronotes.pdf

https://m.eet.com/media/1141271/18042-122602di.pdf

https://www.diystompboxes.com/smfforum/index.php?topic=37679.0

[rankot]

That's probably not crackling, like what's going on in a faulty cable, but a phenomenon known as ripple. It's the bane of every amplitude envelope follower design. I seriously doubt there is anything "wrong" with your vactrols that's producing that sound. Instead of retread a well worn path here, let me just throw a couple links to further reading below.

http://www.geofex.com/article_folders/ecftech/ecftech.htm

It says: "Audible effects of ripple are also most likely to occur if the control element is of the type that can respond very fast. Photocell-based ECF's are relatively immune from audible ripple, simply because photocells don't return from their MAX/ON to MIN/OFF value very fast, and impose a longer decay period without additional circuitry. The same envelope follower circuit used with a transistor as the control element may well result in considerable audible ripple unless the decay period is deliberately smoothed out with additional circuitry or larger value capacitors. The pros and cons of control elements are described in more detail in a section below."

So maybe his choice of LDR is important, if fall time is very small, it will produce ripple (if that is what bothers him)?

But also, maybe resistance range of LDR used is not proper, so op amp is clipping sometimes?

[Kipper4]

Also here's more reading on envelope ripple.

https://www.diystompboxes.com/smfforum/index.php?topic=114323.msg1060987#msg1060987

It can be challenging. A quick forum search for envelope ripple will reward you with more knowledge.

[Strategy]

I used 10k/1M LDRs and diffuse green LED's.

Any specific type, or just some no names?

I just used whatever I could get my hands on, but I didn't mix parts from different sources/batches
I didn't measure for matching or anything.
- Strategy

[bushidov]

Is this the ripple that you folks speak of?

This is what is happening with my XVive VTL5C4/2 vactrol. If that is the case, how do I fix that? Get another vactrol? Roll my own? If roll my own, what LEDs and LDRs and where do I get them?

[Kipper4]

And if you adjust the level pot?


http://beavisaudio.com/schematics/DOD-440-Envelope-Filter-Schematic.htm