Showing posts with label Chips. Show all posts
Showing posts with label Chips. Show all posts

Sunday, October 27, 2013

Quick Tip: Differences in Eurorack Modules

When you have multiple modules of the same brand and type , you might sometimes experience small differences between those Eurorack modules.
Sometimes oscillators are tuned differently and you can't get them to match.
One may sound lower than the other with each's controls identical, yet they sound different..
This is often not something to worry about.

Four A-110 VCOs that look the same,
all sounding (slightly) different.
Although most modules are thoroughly tested, some batches may indeed sound a little different due to (internal) trim-pot settings, differences due to tolerances of the electronic parts, etc...

If you want to compare your modules, it is always smart to check the production date/ batch number on the test label and/or on the PCB (version nr) first.
Usually this can be found at the inner side of the front panel.

If the numbers match, and one of your modules does sound different than the other one, you might check out the trimming pots on the backside of the module on the PCB.
In most cases this can be easily fixed with a small screwdriver once you located the right potentiometer (often printed on the PCB or can be found in a manual).

Sometimes it just has to do with other components.
During the production-years of a module the values of all kinds of parts of your module may have been changed a bit (for example R77, R86, R88).
These differences can sometimes be audible, sometimes only to the trained ear...

Especially the specifications of a main circuit like the 74HC4046 (Used in the Phase Locked Loop - A-196 PLL module) may differ for different manufacturers (even different batches from the same manufacturer) of this circuit.
Because the PLL module is not a precision module like a VCO there are no trimming potentiometers available to balance such tolerances.
You'll just have to live with that...

Friday, June 01, 2012

New Doepfer Re-Designs Due to CA3080 Shortage


After the unplanned re-design of the Dark Energy (due to the unavailability of the CEM3394 chip ) there now seem to be more re-designs of Doepfer Modules coming up.

This time the problem is the availability of CA3080 (and 3080E) chips.
The CA3080 (datasheet PDF) is a 2MHz Operational Trans-conductance Amplifier (OTA), which is used in quite a few Doepfer (and other brands) modules and there seems to be no direct replacement equivalent.
The original chip itself hasn't been produced since 1975 and the wafers have all been used up a couple of years ago, according to some sources.
No-one seems to have decent stock anymore, and there was a buying craze when it went out of production.

That does mean that some Doepfer modules have to be re-designed in the near future because of this obsolete integrated circuit ( like the A-107, A-116, A-127, A-130, A-131, A-132-1, A-141, A-142-1, A-147, A-171). 

This will take a lot of precious time for Doepfer that would otherwise be spent on manufacturing new modules.
Sadly these re-designs will not have any obvious benefit for the customers.

Tuesday, February 28, 2012

CEM chips in Doepfer Modules

After the announcement of the discontinuation of the Dark Energy due to a lack of CEM3394 chips I started  making a basic inventory on what CEM chips were used in which Doepfer Module.

The A-111 VCO2 (discontinued) used one CEM3340
The list is still far from complete, also because there are still many Doepfer modules that i don't own, but i am hoping to be able to crowd-source the rest this way.

Feel free to help me complete the list by posting your findings in the comments or by mailing me your additional info, thank you all in advance.

 A123 High Pass Filter / A-179 Light Controlled Voltage Source:     CEM3320

A-111-1 High End VCO:     CEM3340

A-132-3 DVCA Dual Linear/Exponential VCA:     CEM3360

A-107 Morph. Filter:     CEM3379
A-124 Wasp Filter / A-106-6 XP Filter:     CEM3379
A-109 VC Signal Processor:     CEM3379
*Newer versions of the A-122 Low Pass Filter VCF3:     CEM3379

A-130 VCA (linear) / A-131 VCA (exp.) / A-134 VC Panning:     CEM3381
A-126 Frequency Shifter:     CEM3382

A-111-5 Mini Synthesizer Voice:     CEM3394
Dark Energy , Monophonic Synthesizer:     CEM3394

Sources and more info on what chip is inside your synthesizer:
http://curtiselectromusic.com/,
http://synthtech.com/cems.html and http://www.synthtech.com/cem/cemdata.html
http://sequencer.de/synth/index.php/Chips_in_Synthesizers

Note: Not only CEM chips are used in Doepfer modules, i am also working on a full inventory including Texas Instruments chips and as many others as possible. Feel free to contribute...
Thanks to contributors: George P. Macklin, Jakobsweb...