SKU: 72003354785

Doepfer A-101-1 Vactrol Filter

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Description

Doepfer A-101-1 Vactrol FilterDoepfer A 101 1 Vactrol Filter Eurorack Module For Sale. This module is part of the extensive Doepfer A 100 Modular product line. We're a Doepfer dealer. If you're looking to buy a system, monster case, or large lot of modules, please contact us. This item is new in box, carries the manufacturer's warranty, and ships free within the continental US. All photos shown here were provided by the manufacturer, along with the following product description:

Doepfer A-101-1 Vactrol Filter Eurorack Module For Sale.
This module is part of the extensive Doepfer A-100 Modular product line.

We're a Doepfer dealer. If you're looking to buy a system, monster case, or large lot of modules, please contact us. 

This item is new in box, carries the manufacturer's warranty, and ships free within the continental US. All photos shown here were provided by the manufacturer, along with the following product description: 

This is the first vactrol based module in the A-100 system. A vactrol is a combination of a light depending resistor (LDR) and a LED (light emitting diode) both put into a small light-proof case. Increasing the LED brightness causes a decrease of the LDR resistance (e.g. the light controlled voltage module A-179 is an application of a LDR). This effect can be used in circuits that require variable resistors to obtain the desired function (e.g. VCFs, VCAs, VC phasers, VC trigger delays, VC slew limiters, VC Envelope Generators, VC LFOs, VCOs and many more). The advantage of vactrols compared with other solutions (e.g. OTAs, diodes, transistors or FETs as variable resistors) is that they behave like a normal Ohm resistor and can handle high voltages without causing distortion. This is probably the reason why the sound of vactrol-based circuits usually is described as soft or mellow. Disadvantages are theexpenditure and consequently the expenses and the not exactly defined coherence between LED current and LDR resistance. For each vactrol the LDR resistance decreases when the LED current increases but mechanical and electrical tolerances cause that each vactrol will behave a bit different (e.g. because of the differences in alignement and distance between LED and LDR, different brightness of the LEDs at the same current).

Module A-101-1 is a special multitype filter based on an idea by Nyle A. Steiner (published in Electronic Design, issue  25, December 1974, page 96 ff). The circuit uses the standard non-inverting amplifier filter design. Different filter types (low pass / LP, band pass / BP, high pass / HP) are realized by injecting the audio signal into different points of the circuit and using a common output for all filter types. One may feed three different audio signals into the filter simultaneously. Each signal is filtered correspondingly (LP resp. BP resp. HP) and the sum of the three filtered signals appears at the output. Of course it is possible to feed the same signal to all three inputs. In this case one obtains different combinations of LP/BP/HP according to the settings of the three input attenuators for LP/BP/HP. Even a Notch filter is possible (not available in the original design). The filter inputs are normalled, i.e. the BP input is connected to the LP jack socket provided that no cable is plugged into the BP socket (same applies for HP/BP inputs). 

In contrast to the original circuit vactrols are used instead of diodes as variable resistors for frequency control of the filter. Due to the"crooked" response of vactrols the filter has not an exact frequency control standard (like V/Oct). The inevitable tolerances between different vactrols will lead to an individual sound of each module and individual resonance behaviour. Even the resonance control is realized with vactrols. Consequently this parameter is voltage controlled, too. Resonance can be increased up to self-oscillation. Resonance and consequently self-oscillation may vary with the filter frequency because of vactrol tolerances.

A special feature of the module are the two audio outputs. Out 1 is the output of the original circuit. In the original circuit by Nyle A. Steiner the output level was distinctly dependent upon the resonance (higher resonance = higher output level). Out 2 compensates this behaviour by the usage of an additional vactrol that is connected in series to the vactrol that controls the resonance. This additional vactrol forms an attenuator (or simple VCA) that approximately compensates the level increase for higher resonance settings.

Two LED displays show the current frequency and resonance setting. The LEDs are connected in series to the LEDs inside the vactrols and show consequently the LED illumination inside the vactrols.

Width: 16TE / 16HP / 80.9 mm
Depth: 50 mm (measured from the rear side of the front panel)
Current:
+30mA (+12V) / -30mA (-12V)

 

 

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SKU: 72003354785

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Lauren
Whiting, US
★★★★★ 3
My opinion
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Let me preface this by saying I really liked the story and the characters however, this book is in desperate need of some sort of editing. It's not misspelled words or formatting, but continuous run on sentences. Redundancies within the sentences. There were a couple of paragraphs that I had to go back and reread 3 or 4 times. Overall, I'd say it was worth the read.
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Reviewed in the United States on May 29, 2025
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Phoenix, US
★★★★★ 5
Beautiful
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I love omegaverses I had looked at this one multiple times thinking it's just another book about cocky rock star guys that let fame get to their heads and there are parts like that so I wasn't 100% off. I started reading the second book and met the fmc Astraea from the first one,after she had a run in with the aphla from the gym.😁 it gave me the push to stop and read book one first and im so glad I did this book was amazing their was so many characters I fell in love with hoping they will find their happily ever after. the guys were great, the plot was 🎯, and the ending had me 😭😭😭. I was wondering how nate could ever redeem himself, and he did. the last scene with him was sad, but I also felt it was beautiful. thank you to the author for making a beautiful omegaverse book that gave me all the feels. now I'm jumping straight into book two.
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Reviewed in the United States on March 25, 2025
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Lowell, US
★★★★★ 4
Knot their Omega
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It took me a day to really get into the book, there is a lot happening in the beginning of the story. I wish there was more of a time frame because I felt like something’s happened quickly but they were farther away than I thought so that was a little confusing to me. I felt like there was so much happening but also not enough. As for the story itself I enjoyed it, it was different than other OV I’ve read. Bring the tissues, you will need them. They guys were great, I wish we saw more of Kai and Kenjis relationship. As for Nate…… IYKYK. I enjoyed this book, my first from this author and look forward to reading about Kamaris story. Book: ⭐️⭐️⭐️⭐️/5 Spice: 🌶️.5/5
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Reviewed in the United States on October 24, 2024
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M. Schmitz
Port Orchard, US
★★★★★ 2
Has Potential, Poorly Executed
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I really really wanted to enjoy this book and was looking forward to reading it. However there were just one too many convoluted plot points, sentences just did not flow nicely at times, and I was left with a lot of confusion on my end. I think it has the bones of being a great story but seems like it was rushed and I had to push myself to finish the last of the book and was left with an unsatisfying ending. It’s definitely different from other omegaverse novels I’ve read but not for good reasons. I really think it could be great but needs some serious tweaking and editing before I’d read it again.
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Reviewed in the United States on February 3, 2025
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Carmen Alicea
Alexandria, US
★★★★★ 5
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Rockstars, secrets, and off-the-charts chemistry? Sign me up! Cinder Blaze takes us on a rollercoaster of passion and peril with Knot Their Omega. Blair Vesper, a secret Omega masquerading as an Alpha, strikes a risky deal to tour with Blooming Salvation, a band teetering on the edge of chaos. Enter Icarus Morrigan, the enigmatic manager, and his three complicated and irresistibly sexy rockstars: wild Kenji, icy Kaiser, and fiery Nathaniel. This book delivers steamy Omegaverse drama, sizzling slow-burn romance, and just the right dash of angst. The tension between Blair and the band crackles like electricity onstage, while the societal stakes add depth to the spicy dynamics. Short, sharp, and oh-so-sinful Knot Their Omega will have you hooked from the first note!
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Reviewed in the United States on December 9, 2024

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