Remote Control for the BPBP

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Confusions about the options and possibilities how to combine the BPBP with the Maya remote control, made me decide to start this thread, where all info being scattered over several threads now combined in one place.

Intro
A preamp without a remote control, in particular for controlling the volume, is only half a preamp.
The BPBP is a superb preamp, with a solid circuit design, but most special is the absolute excellent PCB design that makes it stand op top what is possible today.
The circuit design itself was used almost exactly by Mark Levinson (and probably by many others also) over the last 10 years for all their models of Pre-amps, with the difference that they use Fet switches in a linear R-2R network for volume control, where the BPBP uses a standard linear Pot.

A pot can be remote controlled by using a motorized version, with added hardware, but more elegantly is to control the volume digitally.
Fet’s as being used by ML cannot compete with Relays in behaving like ideal switches and also a linear R-2R network is way more complex in # of components and in steering without having any advantage over a logarithmic attenuator, so the choice how to replace the pot was easy to make.


Realisation
In controlling those relays, a remote control is needed, and my attention was caught by the well-designed MAYA remote controller, having lots of options, like Bluetooth and a learning IR remote control, 64 steps to control the volume in 1dB steps, multi-channel select and last but not least a serious display giving lots of information.

A complete Maya system must be seen as a “passive” preamp where the signal comes in, gets attenuated passively via a logarithmic relay switched attenuator and leaves the system without any amplification in between.

As such, Maya is doing a great job.
The BPBP however is an active system with a very high CMRR and dynamic range, where volume control is integrated in the feedback of an Op-Amp.

As good as passive preamps may be, the top of the preamps is reserved for active preamps when looking at test magazines like for instance Stereophile.
An interesting feature is that hardly any high end preamp has a tone control, which is also not available on the BPBP.

There are however some potential restrictions like only having 2 input channels.
For this reason a 6 channel GB was started on this Forum.

Another restriction is, that the BPBP is in its basic form has no provision for a remote control.
To solve this problem, a Volume Control Board (VolCB)* was developed giving the possibility to have 64 steps of 1dB each, to being steered by the same Maya controller that also controls the passive Maya preamp.

And here it is where things are beginning to become complicated.
There are three different boards start with: the BPBP pre-amp, the Volume Control Board that replaces the stereo pot and the Maya controller.
This volume control board (VolCB) can select via the Maya remote control between the 2 channels that are available on the BPBP preamp.
If you wanted more channels at your disposal, there was the 6 channel GB board that is operated manually, but no longer available.
With a new GB PCB would it be possible to select 4 or maybe even 6 channels from a similar external input/output board directly from the existing Volume Control board, because the control hardware is already there.

If someone can give me all the essentials of the 6 input GB, I could make a redesign directly to be controlled from the VCB. Maybe 4 balanced inputs should be enough for most situations?
It would be also nice to add a balanced record output to this external board.

Do not confuse these multi-channel options with the multi-channel boards that Maya supplies for a complete system, because they cannot be used for the purpose of selecting input channels in combination with the BPBP.

In case you are happy with a passive preamp, I think the full Maya system will be an excellent choice with the option to have multiples of 4 input channels either Single Ended or Balanced.
When you want to go for the top in high end active preamps, take the BPBP.
However using the full Maya system with all its features like having many input channels IN FRONT of the BPBP, thus placing two preamps in cascade makes no sense at all and should not even be considered.


To conclude for Stereo Applications:

1) use either the full Maya system with expandable multi-channel inputs, or
2) The BPBP with standard 2 input channels to start with, combined with the Volume Control Board and the Maya controller subset, as in this diagram or (later)

Maya_BPBP.jpg

3) The BPBP with an added multi-channel board (still to be designed) with 4 or 6 balanced input channels to choose from and also equipped with a balanced record output, again combined with the standard Volume Control Board and the Maya controller subset.


* Until now this board was called the “Hans” PCB, but I suggest changing this name from now on in VolCB.
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Hi Hans,

Is your PCB for sale? And for the Maya controller, we just need to controller board? What about microcode, does it need to be a special revision?

Can you please post links to your thread where to get the different PCBs?

Thanks
Do

Hi Do,
The bare VolCB (price still TBA) and the fully populated and working MAYA controller (price 140,- Euro) can be both bought from Tibi, see here

http://www.diyaudio.com/forums/group-buys/289544-maya-r2r-advanced-volume-controller.html

and here

https://docs.google.com/spreadsheet...TKbopFC7S6aw/edit?pref=2&pli=1#gid=1638000354

You will not need a special microcode.

Hans
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Since the VolCB will probably not go in production before the end of May, I have made a slight addition to it, where steering signals for the selection of max. 6 inputs have been made available, to be selected from the standard Maya remote controller.

At the same time I will publish this week the Design + Gerbers for a 4 input PCB, where no alterations to a fully populated BPBP will have to be made. A PCB that will be steered and fully integrated with the VolCB, the BPBP and the MAYA remote controller.
A balanced Tape Out to be also be provided on this board.
Just 4 inputs because this is probably enough for 99% of all cases, thereby not overstressing the budget.

Hans
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Here is the circuit diagram of the "4 channel remote PCB", rest to follow soon.

The working is as follows:
The middle XLR inputs on the BPBP remain to be channel 1.
The outer XLR inputs (the former BPBP channel 2) connect to J7 /J8 of the new boards, see the diagram below, outside the cabinet with short twisted wires, preventing to having to change anything at all to a fully populated BPBP.
J1/J2 on this new board are for Channel 2, J3/J4 for channel 3 and J5/J6 for channel 4.

J9 connects to the VolCB, for selecting the proper channel, J10/J11 are the balanced tape output, coming via J12 from the VolCB, and J13 replaces the channel select switch S1 on de BPBP.


Input Select.jpg

Hans
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Here is the final PCB providing 4 input channels plus a tape output for the BPBP.
I have asked Tibi whether he could produce this board just as the VolCB.
But anybody could take the challenge to make a GB of both boards, this PCB and the VolCB.
The Gerbers are available.

4_3 input select.jpg

The PCB measures 235 x 40 mm.
The text on the left `balanced in´ is misleading and should be ´Tape Out´.

Hans
 
Last edited:

emyeuoi

Member
Paid Member
2010-10-02 6:18 am
Vietnam
Hi Hans,

Just found this thread. The solution with Maya it's really interesting. Thanks for your effort

As per schematic you post the input board is identical of the one I proposed in the 6 input GB. The only difference is that I use 12V relays instead of 5V you propose.
I take the chance to reassure everyone that join my GB that the board that they have bought is fully compatible with Maya board. At least is what I understand reading the posts in this thread but plase let me know if I am wrong.

A question about your new VolCB, with the normal linear 10K pot I can't go more than 2 o'clock rotation. After that the ampli go in DC protection. Is quite annoying but is safe! Maybe in your design you already taking care about?

Best Regards,
Enrico

PS: actually the 6 input GB is not closed, just expired itself. That's is quite strange to me, it"s not the first GB that I run but it's the first time that I have no feedback at all, whatever positive or negative.
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Hi Hans,

Just found this thread. The solution with Maya it's really interesting. Thanks for your effort

As per schematic you post the input board is identical of the one I proposed in the 6 input GB. The only difference is that I use 12V relays instead of 5V you propose.
I take the chance to reassure everyone that join my GB that the board that they have bought is fully compatible with Maya board. At least is what I understand reading the posts in this thread but plase let me know if I am wrong.

A question about your new VolCB, with the normal linear 10K pot I can't go more than 2 o'clock rotation. After that the ampli go in DC protection. Is quite annoying but is safe! Maybe in your design you already taking care about?

Best Regards,
Enrico

PS: actually the 6 input GB is not closed, just expired itself. That's is quite strange to me, it"s not the first GB that I run but it's the first time that I have no feedback at all, whatever positive or negative.

Hi Enrico,

1) I have no details of your 6 input board, maybe you can send me a circuit diagram, then I can confirm if and in what way it can be steered by the VolCB and Maya.

2) There are no 2 o'clock issues with the digital vol pot, because gain goes from -57dB to +6db.

Hans
 

emyeuoi

Member
Paid Member
2010-10-02 6:18 am
Vietnam
Hi Enrico,

1) I have no details of your 6 input board, maybe you can send me a circuit diagram, then I can confirm if and in what way it can be steered by the VolCB and Maya.

2) There are no 2 o'clock issues with the digital vol pot, because gain goes from -57dB to +6db.

Hans

Hi Hans,

Thanks for your reply and for the really good news about the pot.

Attached is the schematic of the 6 input board, not really professional but I hope understandable. Anyway looks similar to your schematic, the +12V (that I take directly from the BP board) is fix to the relays's coil and the switch is done through a 6 contact rotary switch to the GND. The input parts are installed on board near the input.

I am curious about the J7 and J8 in your board. As far I understand looking in the 3D you post here all the 8 XLR are installed in the rear panel and in the rear panel there will be also the 6 original XLR from the BP board. The 2 XLR of the BP input 2 should be connected to the J7 and J8 of the additional input board. If I am right this mean that we have 14 XLR in the rear panel for 4 input (input 1 from the BP and the 3 additional) and all in line. Maybe I miss something?

Best Regards,
Enrico
 

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NATDBERG

Member
2006-11-25 4:52 pm
Being able to use the 6 input board with VolCB would be excellent.

@Hans

In simple terms, how does the input select work from the VolCB? Does it have a 6 way relay which will select the input relay directly, or does it cycle through each input relay one at a time? I just wanted to know for knwoledge's sake, not for a practical reason.

On a different note, is there such a thing out in the world as a simple I2C data transmitter which will respond to simple control like a data wheel and send data to a single, selectable address?

I ask this as I will want to implement a second variable output but one which does not need to be remotely controlled. Your VolCB gives a better output range so is there a way to control only volume level with something simple like a manual data wheel or even a set of DIP switches?
 

NATDBERG

Member
2006-11-25 4:52 pm
I am curious about the J7 and J8 in your board. As far I understand looking in the 3D you post here all the 8 XLR are installed in the rear panel and in the rear panel there will be also the 6 original XLR from the BP board. The 2 XLR of the BP input 2 should be connected to the J7 and J8 of the additional input board. If I am right this mean that we have 14 XLR in the rear panel for 4 input (input 1 from the BP and the 3 additional) and all in line. Maybe I miss something?

Best Regards,
Enrico

My understanding is that the 4 input board sits as a separate board, perhaps even in a separate box. That way it can be added by anyone already using their bppbp as a two input preamp with no changes to the original board.

I'm sure that anyone who wants to and hasn't yet installed their bppbp can instead solder wires directly to the bppbp and extend the bppbp's outputs to the rear panel.
 

NATDBERG

Member
2006-11-25 4:52 pm
I am not sure about a separated box. As far I understand the Maja board will control the inputs and the volume. So there will be a connection from the Maja to the BP preampli for the pot and another connection for the additional input board.

Ah yes, the Maya and VolCB would be in the same box as the BPPBP (so just front panel change addition of the Maya and VolCB boards internally). But the 4 x input board looks to be designed as an expansion board for BPPBP's Input 2 with I2C input select from the VolCB (originating from the Maya).

As an expansion board, it leaves the BPPBP components alone and so can be used both in a separate unit or within the same box, as the user wishes.

I just looked again at Hans' 3D rendering - indeed it is only a 3 input expansion board so requires Input 1 on the BPPBP to be considered as the one of the inputs.

That is slightly different from your 6 input board which replaces all the BPPBP's inputs and output entirely and is should be considered to be integrated by the designer from the very start (as I will be doing).
 
Last edited:

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Hi Hans,

Thanks for your reply and for the really good news about the pot.

Attached is the schematic of the 6 input board, not really professional but I hope understandable. Anyway looks similar to your schematic, the +12V (that I take directly from the BP board) is fix to the relays's coil and the switch is done through a 6 contact rotary switch to the GND. The input parts are installed on board near the input.
The VolCB has 6 outputs, so yes, your board can be controlled by Maya, but only when 5 Volt relays are used, since the I2C chip on the VolCB cannot handle 12 Volt.

I am curious about the J7 and J8 in your board. As far I understand looking in the 3D you post here all the 8 XLR are installed in the rear panel and in the rear panel there will be also the 6 original XLR from the BP board. The 2 XLR of the BP input 2 should be connected to the J7 and J8 of the additional input board. If I am right this mean that we have 14 XLR in the rear panel for 4 input (input 1 from the BP and the 3 additional) and all in line. Maybe I miss something?

Best Regards,
Enrico
The 5 XLR pairs on the "4 Input Select Board" are resp.: Tape Out, Channel 4, Channel 3, Channel 2 and output (J7+J8) to connect to one BPBP input.
The BPBP will keep Channel 1 and the Main Output. Former Channel 2 on the BPBP will be connected to J7+J8 on the 4 Input Select board.

In total the backpanel will show 8 XLR pairs: 5 on the "4 Input Select" + 3 on the BPBP, giving in total 4 Input Channels, 1 Main Output and 1 Tape Output.
The two pairs connecting the two PCB, are making it possible to leave a fully populated BPBP unmodified.

Hans
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
Being able to use the 6 input board with VolCB would be excellent.

@Hans

In simple terms, how does the input select work from the VolCB? Does it have a 6 way relay which will select the input relay directly, or does it cycle through each input relay one at a time? I just wanted to know for knwoledge's sake, not for a practical reason.
Selecting an output to switch a relay is performed directly from a I2C chip, in this case a PCF8574.
On a different note, is there such a thing out in the world as a simple I2C data transmitter which will respond to simple control like a data wheel and send data to a single, selectable address?
To control a I2C chip, you will need a CPU, a simple replacement is not possible.

I ask this as I will want to implement a second variable output but one which does not need to be remotely controlled. Your VolCB gives a better output range so is there a way to control only volume level with something simple like a manual data wheel or even a set of DIP switches?
Yes, by simply removing (or not mounting) the volume PCF8574, you have direct control over the 6 steering lines to select any code between 0 and 63.

Hans