To have the same functionality with 16 volume steps, but without having a connection to ground, you will need per channel 18 resistors to start with.
One resistor has to be permanently connected from output to -input of the "volume amp", to prevent an uncontrolled signal going to your main amp when switching between 2 positions.
And you will need 16 relays plus the logic to control these relays.
This could be a 16 position switch, a 4 bits bcd encoder with decoding logic or a rotary encoder with decoding logic.
The result would be something at least 4 times in volume, and with a very large amount of soldering contacts the signal has to pass.
When possible, the adagium should always be: less is more, especially with (soldering) connections.
And just keep in mind, a pot cannot improve the sound, it can only make it worse.
But technically it is absolutely possible to follow this path.
Hans
. Thank you for confirming.Please ignore this question, if this is off-topic for this thread.
I am about to finish a pair of Hypex monoblocks that uses UCD400HG. Do I need to change any component of the kit provided in tfboy's GB, to suit the Hypex UCD 400 amplifiers?
Here is the link to spec sheet of UCD - http://www.hypex.nl/docs/UcD400HG_datasheet.pdf
I am about to finish a pair of Hypex monoblocks that uses UCD400HG. Do I need to change any component of the kit provided in tfboy's GB, to suit the Hypex UCD 400 amplifiers?
Here is the link to spec sheet of UCD - http://www.hypex.nl/docs/UcD400HG_datasheet.pdf
Line level in and out. High input impedance and low output impedance.
Looks good to me! No need for any actions as I see it.
//
I'm not sure what you are asking. Is it the gain of the digital volume control?
In that case, maximum gain is 6dB.
R12/R10=2x with the diagram that has been published.
Hans
Could you show the formula for gain?
That link gave no formula
May be you can be a bit more specific. What do you need a formula for and what do you want to calculate?
I have used a spreadsheet in which I have aimed for a constant input impedance of 2K and started with Relay 4 giving a 2 dB step.
Then Relay 3 to give a 4 dB step, and so on and so on for 8 dB and 16dB.
Hans
Imagine two resistors R1 and R2 in series with the Op-Amp's -input and a resistor R3 from node R2-R3 going to ground.
The Op-Amp -input is a virtual ground, so in effect R2 and R3 are in parallel.
The voltage arising on the node is thus Vnode = Vin*[(R2//R3)/(R1+R2//R3)].
From here the gain is a steady 6dB, so Vout = 2* Vnode
It is important that the ground used for R2 is the one that is also connected to the +input ground of the Op-Amp.
Hans
Looking around, I found a very interesting alternative for the BPPBP.
The solution is based on the Vicol Maya R-2R solution.
The name R-2R in this respect is a bit misleading because they are steering a 6 bit logarithmic attenuator enabling 64 steps of 1 dB each (and not a R-2R ladder network).
However, their attenuator setup is different, but the CPU part which is located on a separate board, interfaces with open collectors to six volume relays and the selection of four input channels.
The CPU board includes an learning infrared interface for a RC5 remote controller or a NEC (Apple) remote controller.
But it can also be equiped with a Bluetooth interface, to enable the remote control from your Android GSM.
But a rotary encoder is also be attached to change volume and for control functions.
Last but not least, it also has a display, either LCD or OLED.
All you could wish is there, even including the option to install new software releases.
All that is missing is a simple and small relay board having 2* 14 resistors plus 6 relays, to replace the pot.
You will get a control range of 63 dB with a 1 dB stepsize.
This new Relay board can have the same mini size of the existing manual relay board that has 16 steps of 2 dB.
If there is any interest in this combined solution, I will be happy to design this relay board and make the Gerbers available for free.
Hans
P.S. For Maya, there is a group buy going on, but you won't need all the parts coming with this project. For this reason I have contacted Tibi.
The solution is based on the Vicol Maya R-2R solution.
The name R-2R in this respect is a bit misleading because they are steering a 6 bit logarithmic attenuator enabling 64 steps of 1 dB each (and not a R-2R ladder network).
However, their attenuator setup is different, but the CPU part which is located on a separate board, interfaces with open collectors to six volume relays and the selection of four input channels.
The CPU board includes an learning infrared interface for a RC5 remote controller or a NEC (Apple) remote controller.
But it can also be equiped with a Bluetooth interface, to enable the remote control from your Android GSM.
But a rotary encoder is also be attached to change volume and for control functions.
Last but not least, it also has a display, either LCD or OLED.
All you could wish is there, even including the option to install new software releases.
All that is missing is a simple and small relay board having 2* 14 resistors plus 6 relays, to replace the pot.
You will get a control range of 63 dB with a 1 dB stepsize.
This new Relay board can have the same mini size of the existing manual relay board that has 16 steps of 2 dB.
If there is any interest in this combined solution, I will be happy to design this relay board and make the Gerbers available for free.
Hans
P.S. For Maya, there is a group buy going on, but you won't need all the parts coming with this project. For this reason I have contacted Tibi.
Additionally, I just got the following price information from Tibi, based on 100 PCB's.
Price will be 140euro for each unit with bluetooth module and OLED display, or 110 euro without bluetooth module and with LCD display. There is a different firmware for OLED than LCD.
And one correction to my previous posting: the relay board is not steered over open collectors, but over an I2C interface. One digital chip will therefore be needed for the volume control and one for channel selection.
Hans
Price will be 140euro for each unit with bluetooth module and OLED display, or 110 euro without bluetooth module and with LCD display. There is a different firmware for OLED than LCD.
And one correction to my previous posting: the relay board is not steered over open collectors, but over an I2C interface. One digital chip will therefore be needed for the volume control and one for channel selection.
Hans
