I recieved my two LPG 1U modules a few days ago. I am very impressed. My motivation to buy them was in hopes of them replacing my LXd (if they sounded right), and freeing up 4HP of 3U space.
So here are my thoughts on the comparision.
To begin with the LXd has two different LPGs - a 12db/oct (2-pole) and a 6db/oct (1-pole). The LPG 1U is only 6db/oct (1-pole). I have always found the 2-pole LPG to be too harsh, and too fast. If I wanted that sound, I can get it with the fastest AD envelope on the latest Quadrax, and a 2-pole LPF and a trusty Intellijel VCA. Even though this would be more complex of a patch - it has better controls. So, my real desire is to have two of the 1-pole LPGs in LXd… and this is where the Intellijel LPGs are perfectly up to the task. The other physical differences are that the LXd requires power, and has a strike input.
The Intelljel LPGs sound excellent. I find they are even slower than the LXd 1-pole. For me - slower is better - if I wanted fast, I’d just use a VCA - I want to hear that Vactrol! Sending just a trigger from my sequencer - which is basically a “ping” - it has a wonderful decay to it.
The Intellijel LPG has a much brighter attack, and has a slightly brighter decay than the LXd. It sounds much closer to what I have heard of the Buchla 292e and Easel LPGs. Because it is so slow, I find that it is much easier to make it float - ie. never close - when sending it a lot of very fast pings. But this little quirk makes the LPG 1U very unique. It does something you just can’t get out of a VCF/VCA very easily. Sending it varying levels of voltage, between 5V and 1V, has a nice effect on lowering the output level and lowering the cutoff proportionally, but does not change the decay rate. This is where the LXd is slightly more defined. You can almost use CV voltage level as a filter cutoff on the LXd, where the LPG1U is less pronounced.
But for an inexpensive 6HP 1U module - this is fantastic. If I was really focused on these complex details for an LPG - I think I’d invest in a Rabid Elephant Natural Gate (good luck finding one), or a RYO Aperature (haha… again… good luck finding one).
The LXd is an excellent module, but replacing it with two of the new LPG 1U modules, I’ve gained 8HP, which along with some other optimizations, allows me to focus on larger, more complex modules for my 3U real estate.
Cheers to Intellijel! I look forward to more great 1U developments!
Thanks the review!
Thanks for the review!
Excellent review.
I will need the space in my 1u row soon for something new, thinking of building little LEGO cases for the 2 I got, use them a bit like the magnetic robot “puck” mult intelljel used to sell.
Will report back with pics when done
hey, just signed up here to say thank you for the write up. exactly what i was looking for!
Thanks for the review as well.
What kind of Vactrol are they using ? Because depending on the tolerances it can be relatively low or fast.I’ll get one very soon for sure.
There is no code written on the Vactrol visible from the exposed side - and I’d have to desolder it to see the side facing the PCB.
Like I said in my review in July, the LPG 1U is pretty slow - much slower than the 6dB LXd low pass gate for comparison.
I have been habitually using the LPG 1U for a different purpose - not as a filtered gate on audio signals, but as a makeshift slow-decay VCA on modulation signals. Like a “poor-man’s Release Envelope/VCA”.
It is a really fast and effective way of decaying a signal to a modulation destination - here is an example patch - the goal is to apply a slight vibrato at the beginning of a note that smoothly dissipates.
- an LFO source goes to the input of the LPG 1U
- LPG 1U output to the Linear FM of my VCO
- Mult the trigger of your sequencer source to the CV input of LPG 1U
When you hit a note the LFO affects the Linear FM only for the decay of the LPG, and at the amplitude of tthe Linear FM on your VCO.
This allows you to add this vibrato as a completely separate signal effect to the envelopes/VCF/VCAs in the signal downstream of the VCO. I also use this to send little decaying LFO modulation to PWM.
Thanks for the message & patch example.
I used to have Buchla 292e for several yers, several 292c also (clones i built with Excelitas) but from one channel to another, if you don’t match it, it is easy to have different responses. My original 292e B&A by the way had inequal responses from one channel to another…
It is famous that Vactrol are subject to quite high tolerances (some says 20%ish) so i was just curious about it, don’t worry, no need to pull it apart 
. It might be the case that LPG 1U may reacts slightly different from one to another. That’s also the charm of it. I have even seen 227e with open “vactrol” : i.e. LED & LDR without anything else around. It’s also possible to build it yourself quite easily with LED, LDR & heatshrink.
any audio / video to accompany the review?
I’ve since let my intellijel LPGs find a new home since I acquired a Tokyo Tape Music Center TokyoGate, and reduced my 1U real estate from 376HP to 120HP with my new studio case.
I did some demostrations of using the LPGs on this track. All of the voices in this track are gated with Intellijel LPG1Us.
Very nice sounding, Tokyo tape is rad. I wish/would really like that intellijel design a full size LPG á la « natural gate » from rabid elephant (holy graal of lpg in euro). I would be interested in seeing intellijel take on that
awesome job!
Wow, that is awesome. 
Might as well hop in here to see if anyone out there has had any interest in a 3U version of the 1U VCA…. Essentially same design with same normal’d connections. A plug in plug out VCA.
I have both the 1U LPG and the LxD, and I too love the Intellijel version just as much, and sometimes even more! But I think I’ve turned into an Intellijel fanboy over the last two years. 
@Danjel
Is there any chance you could make this an official thing?
I just got one of the 1U LPG modules today and it sounds absolutely gorgeous. I’d love to have more but I don’t have enough space to fill the 1u rail with them.
I can provide the FPE file that I used to create the front panel, if anyone is interested (and if Intellijel doesn’t mind).