Roll Your Own Ampmix & Vertmix SDIY

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MindSnared
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Roll Your Own Ampmix & Vertmix SDIY

Post by MindSnared » Fri Dec 13, 2013 4:17 am

Hello!

We've had a great run with these modules, thanks to all you customers and supporters! We have sold out our stocks of Ampmix and Vertmix and are currently working on the next run which will also feature a slightly improved circuity and a standing resistor layout to make the solder footprints more spaced out.

For those of you unfamiliar with these from our starter thread.

Ampmix

A 4-channel mixer/attenuator with 2.0x gain and 5V offset on each channel in an 8hp module.

Ampmix was designed as a handy CV mixer and processor with buffered inputs but its low-noise circuit means it will also work great with audio, even with full gain.

A 2.5V voltage offset is generated then normaled to the inputs of the 4 channels, giving them a maximum of 5V out each with knobs turned full clockwise (2.0x gain). Please note that these offsets will affect the mixing if the channel hasn't been patched on its input or output, so turning all unused channels fully counter-clockwise/left (off) is advisable for a clean mix.

It works as 4 channel mixer,
1 attenuator + 3 channel mixer,
2 attenuators + 2 channel mixer
or 4 attenuators.
With up to 2.0x gain on each channel.

The buffered inputs offer very large resistorless jFET impedance and is unaffected by output impedance (isolation/protection resistors) on the modules going in to the mixer. If a patch cable is inserted but loose at the other end, the input will be floating (this is modifiable by a resistor between input pin and ground on the inputs jacks, input impedance will then be equal to this resistors value).
The outputs have 1kohm impedance.

Basic specifications
Width: 8hp
Depth with power cable attached:31mm

Assembly manual (Legacy version, new version coming soon)

Vertmix

A 3-channel bipolar mixer/attenuator with 5V offset on channel 1 in an 6hp module.

Vertmix was designed as a handy CV mixer and processor with buffered inputs but its low-noise circuit means it will also work great with audio.

A 5V offset is normaled to the input of the first channel, giving it a maximum of 5V out turned full clockwise/right or minimum of -5V turned fully counter-clockwise/left. Please note that this offset will affect the mixing if the channel hasn't been patched on its input or output.

It works as 3 channel bipolar mixer,
1 bipolar attenuator + 2 channel bipolar mixer
or 3 bipolar attenuators.

The buffered inputs offer very large resistorless jFET impedance and is unaffected by output impedance (isolation/protection resistors) on the modules going in to the mixer. The inputs without offset voltage is grounded if no patch cable are inserted. If a patch cable is inserted in an input but loose at the other end, the input will be floating (this is modifiable by a resistor between input pin and ground on the input jacks, input impedance will then be equal to this resistors value).
The outputs have 1kohm impedance.

Basic specifications
Width: 6hp
Depth with power cable attached:31mm

Assembly manual
Last edited by MindSnared on Sun Oct 05, 2014 2:43 pm, edited 5 times in total.

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Kunfuz
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Post by Kunfuz » Fri Dec 13, 2013 4:34 am

Wow, I said it before and I will say it again.
Incredible good value for the money you ask :yay:

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MindSnared
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Post by MindSnared » Fri Dec 13, 2013 5:08 am

Kunfuz wrote:Wow, I said it before and I will say it again.
Incredible good value for the money you ask :yay:
Thank you for your kind words! It's a lot thanks to the low cost of PCB front panels that allows us to keep this price/functionality ratio with enough profit for R&D and to live of.

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Stinktier86
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Post by Stinktier86 » Fri Dec 13, 2013 6:06 am

Can they be ordered without panels? I'm trying to keep my system all-aluminium. 8_)

Maybe grayscale will do panels for these, too?

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Nantonos
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Post by Nantonos » Fri Dec 13, 2013 7:34 am

One ampmix for me please. Edit: ordered!

Oddly enough I was doing some patching a few days ago and realised that some post-filter outputs were inconveniently low relative to others; rather than attenuate the louder ones I would rather amp up the low ones to regular modular 10v p-p levels. Which implies a need for 2 or 3 amps with 1-2x gain.

Followed by the discovery on modulargrid that the market is not well served with modules offering 2,3 or 4 channels of modest variable gain (1x-3x).

I see that these are mainly intended for CV but will work with audio ok?
ondes | current rack
I am afraid a firmware change will not be able to turn a rather expensive 16-bit DAC into a 16-bit ADC, and flip all those op-amps :)

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MindSnared
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Post by MindSnared » Fri Dec 13, 2013 8:14 am

Nantonos wrote:
I see that these are mainly intended for CV but will work with audio ok?
Thanks for your order!

Yes, we think they work great for audio although the pots are linear on both.

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MindSnared
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Post by MindSnared » Fri Dec 13, 2013 8:16 am

Stinktier86 wrote:Can they be ordered without panels? I'm trying to keep my system all-aluminium. 8_)

Maybe grayscale will do panels for these, too?
I believe he will, but you might want to ask him as well to be sure.

Also yes, the option to purchase without PCB front panel is present on the shop.

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Nantonos
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Post by Nantonos » Fri Dec 13, 2013 9:07 am

I added Ampmix and Vertmix to Modular Grid. Will update once there are mA values.
ondes | current rack
I am afraid a firmware change will not be able to turn a rather expensive 16-bit DAC into a 16-bit ADC, and flip all those op-amps :)

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stabilt
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Post by stabilt » Fri Dec 13, 2013 9:44 am

Thank you. We will be able to measure power consumption on monday evening. We are at family over the weekend.

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Post by Karl_Joseph » Sat Dec 14, 2013 5:32 pm

Great esthetics!
- KARL

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Post by vurma » Sun Dec 15, 2013 2:02 am

Even though my backlog is large as it is, i'm getting a kit just to support your business. Support your local wiggler, etc. etc.
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MindSnared
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Post by MindSnared » Thu Dec 19, 2013 7:51 pm

Thank you vurma and Karl_Joseph! :nana:

The front panels have arrived and stock has been added. All preorders have been shipped.

Holidays are upon us and we will put in an extra effort so that orders of KITs placed before tomorrow 20 dec 2013 14:00 CET will be shipped the same day. If you choose posten with no insurance/tracking orders before 17:00 CET will be shipped the same day. Next earliest date of dispatch will be 27 dec 2013 and after that it goes back to normal.

Happy holidays and goodnight!

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MindSnared
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Post by MindSnared » Mon Dec 23, 2013 8:34 am

Just liked to pop in and say BOM + build docs for Ampmix are now finished and is available here and of course via the webshop:

http://ljunggrenaudio.com/products/AMPM ... Manual.pdf

Happy seasons everyone :party:

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Post by j9k » Wed Jan 22, 2014 1:30 am

I just got my AMPMIX board and front panel. They look amazing! great work.

I can't wait for the WOFLTR to be released.
http://www.jninek.com/

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phala
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Post by phala » Sun Feb 23, 2014 6:57 pm

just finished the AMPMIX kit....just great! really good price point and a beauty of a kit!
:tu:

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Post by ben_hex » Sun Feb 23, 2014 7:38 pm

Amp mix looks great, so does vertmix be great next to a quad envelope to attenuate and invert to send around the modular.
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Post by Ginko » Sun Mar 16, 2014 7:32 am

I was playing with Vertmix today and realised it wasn't working the way I thought it did - I thought if you had nothing plugged into channel 1 then the channel 1 control acted as a bias control for outputs 2 and 3, but it only seems to bias output 3 - is this correct?

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MindSnared
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Post by MindSnared » Sun Mar 16, 2014 5:21 pm

Thanks guys for the support, we're glad you like the kits!
Roll Your Own - ljunggrenaudio.com

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MindSnared
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Post by MindSnared » Sun Mar 16, 2014 5:28 pm

Ginko wrote:I was playing with Vertmix today and realised it wasn't working the way I thought it did - I thought if you had nothing plugged into channel 1 then the channel 1 control acted as a bias control for outputs 2 and 3, but it only seems to bias output 3 - is this correct?
Yes, channels 1 and 2 are mixed to the channel 3 output only, so you either take the offset out directly at output 1 or mix it together with channel 2 and 3s incoming signals when nothing is patched in/out of channel 1.

Ampmix is normalled in the same way, only channel 4 out gives a mixed output, which breaks if you patch a cable into the outputs of channel 1, 2 and 3. The Ampmix also has a +5V offset on all 4 channels, compared to Vertmix that has a -5V to +5V offset on channel 1 only.
Roll Your Own - ljunggrenaudio.com

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Ginko
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Post by Ginko » Sun Mar 16, 2014 6:08 pm

MindSnared wrote:Yes, channels 1 and 2 are mixed to the channel 3 output only
Ok, I kinda figured this would be the case after I posted earlier but couldn't try it out.
MindSnared wrote:so you either take the offset out directly at output 1 or mix it together with channel 2 and 3s incoming signals when nothing is patched in/out of channel 1.
So just to check:

If I plug a signal into Ch 1 input and patch Ch 1 output - Ch 1 works as a bi-polar mixer right? and the case is the same for any of the channels.

If I plug a signal into Ch 2 and Ch 3 inputs, they are both offset with Ch 1 knob but only at Ch 3 mix output (unless I patch something into Ch 2 output)?

What happens (if anything) if I plug a signal into Ch 1 input but patch nothing to the output?

I'm not quite sure what you mean by "take the offset out directly at channel 1" - which channel is offset in this case?

Sorry for all the questions (and I probably could figure this out just by doing a bit of patching) :hihi: Module has been really useful so far though!!

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MindSnared
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Post by MindSnared » Sun Mar 16, 2014 7:26 pm

Hey, I'll answer each question separately so you might get the same answer more than once but I thought it was better to make it less confusing :)
Ginko wrote: If I plug a signal into Ch 1 input and patch Ch 1 output - Ch 1 works as a bi-polar mixer right? and the case is the same for any of the channels.
Each of the channels are capable of working as stand-alone bipolar attenuators (attenuverters), channel 1 and 2 outputs are normalled to channel 3 output to give the module mixer functionality, so for instance if you want to use it as a 3-channel attenuverting mixer connect 3 different signals to all 3 channels inputs and take the mix out on channel 3 output, to exclude channel 2 and 3 from the mix and thus use the module as 3 separate attenuverters just patch cables to channel 1 and 2 outputs to exclude these from the mix.
Ginko wrote: If I plug a signal into Ch 2 and Ch 3 inputs, they are both offset with Ch 1 knob but only at Ch 3 mix output (unless I patch something into Ch 2 output)?
Yes, in this patch example the signals going into channel 2 and 3 as well as the voltage offset on channel 1 (because nothing is patched to its input or output) will be mixed to channel 3 output. If you now patch a cable to channel 2 output then channel 2 will be excluded from the mix leaving channel 1 and channel 3 mixed.
Ginko wrote: What happens (if anything) if I plug a signal into Ch 1 input but patch nothing to the output?
The offset voltage normalization to the input will break.
Ginko wrote: I'm not quite sure what you mean by "take the offset out directly at channel 1" - which channel is offset in this case?
Since the offset voltage is normalled to channel 1 input you can just patch a cable to the output and use the pot to attenuate/invert the voltage offset until happy.

Glad to gear you are finding good use for the module, if there is anything you wonder still don't hesitate to ask more questions! :)
Roll Your Own - ljunggrenaudio.com

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MindSnared
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Post by MindSnared » Sun Mar 16, 2014 7:26 pm

Doppelganger post
Roll Your Own - ljunggrenaudio.com

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Post by Ginko » Mon Mar 17, 2014 2:21 am

Cheers, thanks for clearing that up :tu:

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Post by charonme » Sat Mar 22, 2014 6:52 am

I just finished building the vertmix and realized at the end that the -12v power pin is on the top.....

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Post by Ginko » Sat Mar 22, 2014 7:48 am

Did you realise that before or after the smoke? :deadbanana:

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