Such feature can be implemented still with a single Maya controller by adapting firmware and changing R-2R board to allow PCF addressing via I2C bus.
So, it is possible with some effort.
I wonder how many people are interested in such function.
Regards,
Tibi
Tibi,
I see no provision for setting different I2C addresses on the circuit diagram of the R2R board that I have, needed when using more that 4 input channels.
View attachment Schematic MAYA 3.2.pdf
Volume Control has address 0 and Channel Select address 4 in this diagram.
But there is a connector Aux1 that leads P3 to P7 from the channel select PCF to the outside world.
So I suspect, in case of extending the amount of channels to 8 or 12, you need a different type of R-2R board that can input P3 to P7 as it's address?
The reason I'm asking has to do with the question whether a slight change to the Hans board can facilitate the use of more BPBP amps, without having to change anything at all to the software of the Maya CPU control.
Since this "Hans" board isn't yet in production, I could still easily make a new set of Gerbers.
Hans
I see no provision for setting different I2C addresses on the circuit diagram of the R2R board that I have, needed when using more that 4 input channels.
View attachment Schematic MAYA 3.2.pdf
Volume Control has address 0 and Channel Select address 4 in this diagram.
But there is a connector Aux1 that leads P3 to P7 from the channel select PCF to the outside world.
So I suspect, in case of extending the amount of channels to 8 or 12, you need a different type of R-2R board that can input P3 to P7 as it's address?
The reason I'm asking has to do with the question whether a slight change to the Hans board can facilitate the use of more BPBP amps, without having to change anything at all to the software of the Maya CPU control.
Since this "Hans" board isn't yet in production, I could still easily make a new set of Gerbers.
Hans
Hi Hans,
Addressing can be provisioned via A0,A1,A3 for each PCF/PCA8574. A 6 position switch or some pcb soldering bulbs must be added to set each board slave addressing.
For further expanding can be used drop in replacement PCA9674.
Maya will interrogate via i2c and "detect" how many slave boards are attached.
Regards,
Tibi
Addressing can be provisioned via A0,A1,A3 for each PCF/PCA8574. A 6 position switch or some pcb soldering bulbs must be added to set each board slave addressing.
For further expanding can be used drop in replacement PCA9674.
Maya will interrogate via i2c and "detect" how many slave boards are attached.
Regards,
Tibi
Linearity as set out in Bruno Putzey's design ONLY applies to using a potentiometer and how, as a potential divider, this is important in the feedback loop (where the pot is used) to prevent distortion. Hans gave a good explanation of this on the main BPPBP thread a couple of days ago.
If you're using an R2R ladder, or a scheme using fixed resistors rather than a continuous track, one can go back to using logarithmic for convenience of use. It's added expense though for no sonic gain, only certain conveniences.
The whole idea of Bruno's clever volume scheme using the cheap linear pot is to negate the whole compromise/distortion of using a fancy and expensive pot / stepped attenuator in the conventional way. In his own circuit build he accidentally used a log pot and it worked ok, just there was more distortion measured than there should have been (than with the linear pot). If you can live with the idiosyncrisies of a linear pot's volume position, a cheap one will perform (sonically - maybe not absolute longevity) as good as any other type.
Hi Tibi,
Thanks for your response.
Sorry for all the trouble, but your answer brings me to the following 4 Questions:
1) When you say "for each PCF", does that mean selectable addresses for the Volume Select PCF and for Channel Select PCF?
2) And if dual addresses per board are used, in case of using THREE R-2R MAYA boards, are the addresses for the two PCF,s set to resp 0/4 (board1), 1/5 (board2) and 2/6 (board3) ?
3) Which PCF's are interrogated to detect how many boards are used, the Volume PCF or the Channel Select PCF?
4) When each Volume PCF has a different address per R-2R board, what happens to its volume setting after switching to another R-2R board. Will it remain in its last used position or not.
Could you please be as specific as possible in answering these questions.
It might open the door to enable extra features to the use of multiple BPBP boards, without you having to change anything at all to the CPU software.
Regards,
Hans
Hi Hans,
1. Controller will scan for all I2C bus addresses, this way perform a pre-check.
2. Yes, you figured correctly, as per table 5.
3. Both
4. Maya will keep in memory only volume per channel. This allow different volume for each input.
What are the features BPBP users are looking for ?
If requests are coherent we may adapt Maya firmware for this specific project.
Regards,
Tibi
1. Controller will scan for all I2C bus addresses, this way perform a pre-check.
2. Yes, you figured correctly, as per table 5.
3. Both
4. Maya will keep in memory only volume per channel. This allow different volume for each input.
What are the features BPBP users are looking for ?
If requests are coherent we may adapt Maya firmware for this specific project.
Regards,
Tibi
O.K., I am getting more detailed idea now.
But the more I go into detail, the more I doubt what to enable and what not.
So let me think it over again, before bombarding you with further questions.
Hans.
Hi Tibi,
Of all the possible options, I see only one thing as being useful, all the others can be solved in different ways.
Let me explain first that the BPBP has only one relay for selecting channel one or channel two. It is thus not possible to deselect both channels.
In case of using more BPBP's at the same time, this means that on every preamp one of the two input channels is always active.
But this is exactly that you want when playing a Multichannel Surround System or a Multichannel Loudspeaker System for low/mid/high.
For the PCF's this would imply all Volume PCF's addresses set to zero and all Channel Select PCF's addresses set to 4 to get the proper synchronisation between the pre-amps.
However when reading PCF's this would mean that the SDA lines are driven by more than one PCF. But since they carry the same information, I do not see any problem.
Do you agree?
In that case nothing has to be changed to the "Hans" board at all and your software can also stay as it is.
If we agree, we can close the books, and I will explain to the BPBP Forum what they can expect.
Hans
Of all the possible options, I see only one thing as being useful, all the others can be solved in different ways.
Let me explain first that the BPBP has only one relay for selecting channel one or channel two. It is thus not possible to deselect both channels.
In case of using more BPBP's at the same time, this means that on every preamp one of the two input channels is always active.
But this is exactly that you want when playing a Multichannel Surround System or a Multichannel Loudspeaker System for low/mid/high.
For the PCF's this would imply all Volume PCF's addresses set to zero and all Channel Select PCF's addresses set to 4 to get the proper synchronisation between the pre-amps.
However when reading PCF's this would mean that the SDA lines are driven by more than one PCF. But since they carry the same information, I do not see any problem.
Do you agree?
In that case nothing has to be changed to the "Hans" board at all and your software can also stay as it is.
If we agree, we can close the books, and I will explain to the BPBP Forum what they can expect.
Hans
I am not sure, whether I understand everything.
The Maya "system", as offered on "vicol-audio.ro" is a volume- and selectable input- (4) controller on steroids.
BPPBP is also a volume- and selectable input- (2) controller.
Both realize, what is commonly called a "passive Preamp".
If I want to switch between more than 2 sources, I need more BPPBPs. However, on each BPPBP I install, one source will always electrically be switched on, the micro-controller on the Maya, however, is aware of this and does some 'magic' in order to have the undesired source(s) muted? How can it do so, if the the source from a BPPBP electrically 'online'?
Should I want 4 inputs I would need 2x BPPBP, 2x 'hans' boards and 1x 'Main MAYA board OLED+bluetooth'.
Should I want to have a Tape-Loop, what could I do? I guess this would not be possible with a major rework of everything?!
As far as I have understood BPPBP, it tries to deliver an ideal GND and thus become dead silent. But the project's idea is closely related to the volume-control he has set up for it. If we now replace Putzeys' volume control with the Maya+hans, wouldn't this eliminate the work of Putzeys?
Please see attached the schema of Maya from 'vicol-audio.ro'. Did I interpret the changes in the right way?
Thank you.
The Maya "system", as offered on "vicol-audio.ro" is a volume- and selectable input- (4) controller on steroids.
BPPBP is also a volume- and selectable input- (2) controller.
Both realize, what is commonly called a "passive Preamp".
If I want to switch between more than 2 sources, I need more BPPBPs. However, on each BPPBP I install, one source will always electrically be switched on, the micro-controller on the Maya, however, is aware of this and does some 'magic' in order to have the undesired source(s) muted? How can it do so, if the the source from a BPPBP electrically 'online'?
Should I want 4 inputs I would need 2x BPPBP, 2x 'hans' boards and 1x 'Main MAYA board OLED+bluetooth'.
Should I want to have a Tape-Loop, what could I do? I guess this would not be possible with a major rework of everything?!
As far as I have understood BPPBP, it tries to deliver an ideal GND and thus become dead silent. But the project's idea is closely related to the volume-control he has set up for it. If we now replace Putzeys' volume control with the Maya+hans, wouldn't this eliminate the work of Putzeys?
Please see attached the schema of Maya from 'vicol-audio.ro'. Did I interpret the changes in the right way?
Thank you.
Attachments
The BPPBP was a board Putzey designed just to show his concept and just so happened to only make it with two inputs.
If you want to add more inputs, you can remove the input switching relay from the design and instead add your own multiple input board/scheme, with the output from this going to the input connections on the BPPBP in place of the relay.
With regard to the Maya + Hans' board though, the Hans board only connects to the BPPBP's input switch by the look of it, so will only be able to switch between the original two inputs as per the standard BPPBP implementation.
It might be possible that the input switching of Hans' board could be left out and instead the Maya and Maya's own input board used?
Hans explained to me a couple of ways to implement a tape loop with a second BPPBP on the main BPPBP thread - I'd have to go back to reference his ideas but essentially the more ideal way would be to take the output from one of the opamps on the first board and feed it to the second at the same place in the circuit. Essentially splitting the signal after the differential input section between two boards (forgive me for a probable lack of correct technical terms here!)
The average tape loop on a preamp has just a fixed level so I guess there would be no need to use the Maya controller to control the tape loop - that wouldn't be a tape loop but a fully fuctioning dual output. You can set the level internally though (or via the back panel) by just using the regular linear pot on this second board.
Hans' board simply replaces the linear pot with an R-2R ladder - it doesn't change the design philosophy of the BPPBP one bit (well, I guess you could say that Bruno's delight in using a very cheap linear pot WAS part of the design philosophy, to demonstrate how it avoids the use of fancy, expensive volume pots..).
I think you are seeing the BPPBP + Maya the wrong way around.
Hans' board just means you can use the Maya controller alone to control volume and input on the BPPBP.
It is not the case that the BPPBP replaces the input section of the full Maya implementation.
In other words, one needs to see it coming from the BPPBP perspective, additional parts for that and not to see it from the full Maya's perspective.
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I need a versatile, audiophile pre-stage. Sources are: network-streamer, tape-deck (still have lots of very special mix-tapes), CD-player. Later I may add tuner and a phono pre. And a line-in to spare is always good.
I want to build seperates or do an integrated amp with Class-D modules (Hypex NC400 or Sure AA-AB32313 or Sure AA-AB32512). Of course, I want soft-start and soft-stop, RC. I need to add speaker-protection to the power-amp. At least the Sure AAs may require it.
Since Putzeys' design seems to be so successful and is relatively cheap, I wanted to go for it, but I disliked very much the volume-control. Your project seems well laid out and modern (!) and when I saw, that other people wanted to combine it with the BPPBP, I started to think about it myself. However, I am not quite sure, whether I can do what I want. And I also have to check a little bit on money. I can get good vintage-pres (Yamaha CX-1, C80, Quad, etc.) on eBay for around 300-400€. This is why I am asking those questions, so I know the territory around me. I am a newbie to all of this and only realize slowly.
Not sure where others stand, but this may make a revision of the BPPBP (or the hansboard, probably both?) interesting, where this is being taken into consideration.
I will check it out. Thanks for pointer.
Hi Tibi,
I am attempting to update the firmware per your instructions. I have purchased and assembled a USBtinyISP programmer. Next your instructions say to get a fuse calculator. It is not clear what I need to do with the fuse calculator.
I have the Arduino IDE installed on my Macbook. Can I use that to update firmware?
I am attempting to update the firmware per your instructions. I have purchased and assembled a USBtinyISP programmer. Next your instructions say to get a fuse calculator. It is not clear what I need to do with the fuse calculator.
I have the Arduino IDE installed on my Macbook. Can I use that to update firmware?
Hi,
Indeed, document can be confusing. I'll delete below from document, as it may generate confusion.
"Next step is to get an Atmel AVR fuse calculator. Use Google to search for one, or use this one
Engbedded AVR Fuse Calculator
In our particular case (ATMega32) AVRDUDE arguments are -U lfuse:w:0xd4:m -U hfuse:w:0xd9:m"
Your next step is to follow what is written in red in the document. There are three command line. That's all.
You can not use Arduino IDE.
Thanks & Regards,
Tibi
PS. Please use the other thread for support as we mix two GB.
Indeed, document can be confusing. I'll delete below from document, as it may generate confusion.
"Next step is to get an Atmel AVR fuse calculator. Use Google to search for one, or use this one
Engbedded AVR Fuse Calculator
In our particular case (ATMega32) AVRDUDE arguments are -U lfuse:w:0xd4:m -U hfuse:w:0xd9:m"
Your next step is to follow what is written in red in the document. There are three command line. That's all.
You can not use Arduino IDE.
Thanks & Regards,
Tibi
PS. Please use the other thread for support as we mix two GB.
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