BPPBP - Bruno Putzey's Purist Balanced Preamp (well a balanced volume control really)

[noviygera]

Is this pre amp like a balanced version of TI buffered attenuator test board?
http://www.ti.com/tool/TIPD136

 

[Martant]

Since the Maya solution with VolCB is no longer available, and Arduino solutions are coming up, I could provide this PCB if there is still demand for.

Hans

Dear Hans, the Arduino solution to replace Maya VolCB would be very welcome. A specific reason to this is that Arduino programming is familiar to many of us. This fact enables customization of the system according to personal needs. It woud be a nice feature if also input selection is included in the solution.

 

[noviygera]

If I have a single ended source going into BPPBP, am I still getting BAL output?

 

[Nikon1975]

If I have a single ended source going into BPPBP, am I still getting BAL output?

Yes

 

[noviygera]

😎

 

[kn0ppers]

Since there are regularly people asking for PCBs:

I have a few (six as of right now) of the original PCB that I could spare. Green soldermask, leaded HASL, 1oz/35µm copper layers, 140-150°C TG FR-4. I am asking for what I paid a piece (2,50€) + postage within the EU from Germany.

Apart from that I would also appreciate an arduino based version of a VolCB.

 

[alexcp]

Controlling VolCB with Arduino

I did attach a sample sketch to post #889. It is functional but rather basic and was intended as a starting point. There seems to be interest in a more complete solution.

What features do you think an Arduino sketch needs in order to be useful?

 

[noviygera]

What power transformer should I get for this pre-amp (secondaries/va rating)?

 

[noviygera]

Do I need two secondaries with 12v each or can I use a center tapped 24v?

 

[alexcp]

You can use one center tapped secondary. Dual 12V secondaries of one 24V center tapped should be adequate.

 

[noviygera]

Last question regarding transformer:
Toroidal or regular one?

Thanks!

 

[alexcp]

I use toroids where possible, but I see no reason why any other transformer would not do the job.

 

[NATDBERG]

I'm frequently questioned concerning the IM23TS relay that I used for the volume control boards.
These relays were long time out of stock, but momentarily Farnell has a few thousands of them.

But in case using another relay, be aware that the PCF8574AT driver can only sink 80mA.
So with 6 relays, that's a max of 13mA per relay.
However the pin replaceable PCA8574AD can sink 200mA or 33mA per relay giving you more options for a relay selection.

Hans

They're still there, 700 left..

https://uk.farnell.com/te-connectivity/im23ts/relay-signal-dpdt-250vac-220vdc/dp/1629004

Have they always been £3 each?

 

[NATDBERG]

What would be the proper way of connecting RCA jacks to the inputs, since my sources are all unbalanced at this point?

Alternatively, to fit with any other design, you can buy RCAs in XLR-style back panel fittings, e.g. :

Neutrik NF2D-B-0 RCA Panel Mount Jack w/Colored Isolation Washer Black

Then you connect it to the board as set out in Bruno's paper .

 

[noviygera]

I've got a SilentSwitcher power supply that would work nicely to provide +/-15v dc to my BPPBP. Where's the best location to connect the dc power?

 

[Hans Polak]

I have five VolCB's and four 4 input boards available. PM me in case anybody need some.

Hans

 

[billshurv]

Hans: I'll email you later. I may need 3 vol PCBs

 

[Hans Polak]

Hans: I'll email you later. I may need 3 vol PCBs

That’s o.k.

 

[geoturbo]

Tried to spot a reply for this one but did not find any info, lit's a long shot I guess.. is anyone using a Meldano Muses volume controller as volume pot for this Bppbp?

 

[misterdog]

Good question, maybe try on the Muses thread also. I see Meldano has a new GB starting.

Muses Volume

Remote control and display would be cool.