Which attenuator type for xBosoz and Aleph30

[hifimaker]

A couple of years ago I seem to remember some comments from the master about which attuenator topologies work with the output of the Bosoz when connected to a Pass Aleph30.

A ladder Attuenator seems like the "no compromise" best option, but is much more expensive and takes lots of space.

QUESTION:

Are there any disadvantages to using a serial or shunt design for the output of an xBosoz connected to an Aleph30?

Thank you,

-David


Attuenator Descriptions:
Serial Type
It uses the resistor in series. The advantage of this is that it only requires one deck (layer) of each channel selection and the input impedance can be kept in constant. The disadvantage of this is that the signal (sound) path pass through a "series" of resistors and may cause a higher noise level!

Shunt Type
The signal path only pass through two resistors. It also requires one deck (layer) for each channel selection. The drawback of this application is that its input impedance is a variant. Its input impedance will be higher when the resistor value increase!

Ladder Type
The signal path only pass through two resistors. In theory, it has the lowest noise and the input impedance is stable. However, it requires 2 decks (layers) for each channel and therefore, the quantity of resistors used is double when compare to the Serial type. And the other drawback is its higher cost.

[wuffwaff]

Hi,

I´ve used the shunt design in my X-BOSOZ. Used 1k2 output resistors and a 24 position two deck Elma switch (for both channels).

This works fine and the output impedance is actually very low except for the highest positions (max. 2k4 balanced, 1k2 unbalanced)) wich I never use.

When you are using a non CCS X-BOSOZ and want to use the single ended output too, you will have to put a switch in that connects one output (-OUT) to ground.

I´ve got an excel sheet where you can calculate the resistor values for different steps and output resistors. I you want it I can sent it to you.

The input impedance is also fairly constant except for the highest settings ( 2 x Rout + Rshunt). Because the resistor values get quite low after a few steps.

William

[hifimaker]

Thanks William. I'll send you and email for the calculator.

How well would something like this work? What are the down sides?

Thank you,

-David

[wuffwaff]

Hi,

this would also work although 10k is a bit much. You do need a programmed pic and a few relais plus encoder to make it work and have more resistors / contacts in the signal path.

William