The following setting results in a neutral setting of all stages:
1. Insert the unit with the ON switch (17)
2. Set the General Distortion k2 control (1) all to the left (no distortion will be added)
3. Set the General Distortion k3 control (2) all to the left (no distortion will be added)
4. Set the ADD k2 control (9) to the 0 position (center - no distortion will be added)
5. Set the ADD k3 control (16) to the 0 position (center - no distortion will be added)
6. Set the Drive Control (8) to the 0 position (center - no level shift)
7. Set the Drive Control (14) to the 0 position (center - no level shift)
8. Release the Mult switches (4, 6, 11, 13) of the filters
9. Set the low pass filter controls (3 / 10) all to the right
10. Set the high pass filter controls (5 / 12) all to the left
a) Using the different functions of the harmonics generator depends on the taste of the engineer and producer and on the structure mix. Therefore, there is no general procedure for the adjustment.
b) Since the only problems that might come up are too much distortion in the output signal and/or too high level on one of the harmonics generators, nothing else has tobe considered that is of any importance.
c) Make sure that the drive controls (8 & 14) are set to a position where the level indicators (7 & 15) are yellow to orange but not red, to make shure that the input level of the generators is okay for propper operation. If the level throughout the mix is not constant, use a high level passage for the setting.
We can adapt the control ranges to your needs. Please let us know what you are looking for here.
Inputs and Outputs
The modules is available with electronically balanced and transformer balanced outputs. The inputs are always transformer balances, since the input transformers are included in the General k3 section.
The colors of the faceplate, the control knobs, and switch caps can be determined by the customer.
Please, check for details here.
Why is the distortion level so different when I use the filters extensively?
The effect of different input levels on the harmonics generator section is explained in detail in the boxes for k2 and k3. Please read the text to learn about the background.
When using the filters extensively to cut out a small band, it depends on the spectrum of the mix how this filter setting affects the output level. Usually the level will drop dramatically when the frequency band is very small. Any kind of additional regulation would result in some kind of compressor at the input of the generators to keep the input level in a constant range. However, this would also result in an entirely different behavior of the generators. Every time the level drops, the regulator would drive up the level again, so the distortion would not drop down with the level but remain constant or at least high, also with low input levels. Of course there is no rule to determine a threshold level for the regulation in general, since the filtering makes necessary that also very low levels that result from filtering of small bands, can be processed. The only way out is to use the drive control in combination with the level indicator.
Affects the General Distortion settings the k2 and k3 generators?
Yes, the output of the general distortion section drives both the k2 generator and the k3 generator.
Affects the k2 setting the k3 generator?
No, only the general distortion section affects the generators. The k2 and the k3 section is driven from the output of the general distortion section. The outputs are added directly to the output driver amplifier.
I've been using the drive control to shift the level up till the LED was red. The harmonics are different but sound very nice. What happens with this setting?
When the LED indicator color becomes red, the input level will exceed the linear operation range of the particular generator. With red color, you simply clip the generator. It will not output clean k2 or k3 anymore but a mix of different harmonics. The combination of the harmonics is different from the effect that occurs when clipping a normal amplifier. In addition, both generators react differently. There is no reason why you shouldn't use this range if the result is of advantage. It's not the intended use, but you will not damage anything or get any disadvantage from using that range.
The general k3 control is very intested; however, it would be a perfect thing if there are some more controls to modify the behaviour. Is this possible?
Yes and no. The network that simulates the pentode is designed in a way, that the transition range is very high to allow sensitive regulation and to produce high k3 and low k2 and k4 harmonics. If you tell us what you'de like, we can change this network. There is no room for more controls on the faceplate of the U794 anymore, so additional pots to modify the behaviour of the network are not possible. Please have look at the U784 Colorizer that offers some different distortion effects. In addition we are pondering on an additional device that offers one or two networks with a full set of controls for the modification of the behaviour. If this module is of interest for some customers, we're gonna make it in the near future.
If you have any questions or comments, please let us know.