Versatile and comfortable passive pre-amp

[Rudi_Ratlos]

@Wineds: I appreciate very much to make this group-buy a real success!
But I need a companion on my side (offering the PCBs and several of its components) as well! Are you?

Best regards - Rudi

 

[wineds]

Gentlemen, I feel happy and respect your requests (see attached image).
But: is there anyone (Wineds?) and complies to my requests as well: "double-check" the BoM, cut the extension PCB and match the SILONEX LDRs?

Best regards - Rudi_Ratlos

Ok Rudi you want me to match the ldrs? I have done it before when I built a lightspeed. I think I bought about twenty and only got a few good matched sets. I am on the other side of the world to you in case that matters?

 

[Rudi_Ratlos]

What is a distance of about 20.000 Km to make this project a real gem? 😉

We will do it - Wineds!

Best regards - Rudi

 

[jean-paul]

1. The µProcessor communicates with the IR-detector using the RC5 protocol (developed by Philips end of the 1980th.)
It does not understand RC5+, nor does it understand RC6 or any proprietary protocol.
So do not expect the VCpre to understand the protocol that your brand-new Panasonic (or any other brand) handheld transmits to it.
I use an old Philips television handheld (RC437HQN) and it works beautifully.

An Apple remote is one of the best and a good candidate for a nice preamp....it is also quite "preiswert".

http://en.wikipedia.org/wiki/Apple_Remote

BTW it seems the VCPre is getting better and better by the time (at least on paper). Still worried about the close distance between the transformer and the relays/inputs. Will see if it works out. i will be building one.
You could have used SMD 0805 resistors/diodes/caps around the PIC and save board space. Then the transformer could go to the lower side of the PCB (a tad to the right) and the 230 V connector could be left of the transformer.

Regarding the transformer: we used a small and silent Tamura type that has 2 x 8 V secondaries and 2 x 115 V primaries which makes it easy for US guys. The outer pins are 115 V on the US version and the EU people can use a small bridge wire and use the 2 x 115 V version. Please see this impression of the PSU PCB:

http://www.diyaudio.com/forums/grou...-wm8804-spdif-power-supply-pcb-group-buy.html

You probably get an idea why designing my PCBs takes months.....Well it is a virtue to know your own shortcomings 😉

 

[wirewiggler]

Rudi,
Jean-Paul's suggestion of using the apple remote would be an elegant solution. I know it would require a some change in the code but I think it would be worth it.

Bill

 

[Rudi_Ratlos]

Jean-Paul, feel free and position the small transformer anywhere in your case.
You will have to run 2 wires to the rectifier then.

I suppose that METAL will post an answer when it comes to "talking like an APPLE".

Best regards - Rudi

 

[jean-paul]

Regardless of loving or hating Apple, their remote is really a piece of work. Feels good and functions just like it should. Way better than all those plastic universal stuff.

Did you also get my point of the 115 V versus 230 V transformer ? That is if you want to make the PCB available for US citizens. They don't deserve it for PRISM but hey let's be flexible 😀 The NSA already know of this project anyway and they're decrypting the BOM and schematics right now...

Rudi, do you really think I will be using an external transformer ? I just love the VCPre's one board approach. I happen to have sheets of mumetal that will solve any "not yet existing" problem with 50 Hz hum. And I can use a small toroid transformer and drill a hole just right of the 230 V tracks with an insulation washer in it for M4 screws:

http://nl.farnell.com/multicomp/mcfm32-07/transformer-mini-3-2va-2-x-7v/dp/9531386

Please move the track to pin1 of the EI38 transformer just a millimeter to the left 😉 You see for 10 Euro you can not go wrong with these small toroids. I use them a lot and they're silent and have a virtually non existent stray field compared to EI transformers. In fact it is a worthwhile upgrade and solves the 115 V /230 V dilemma.

 

[voxxonline]

I dont use apple , but this remote is neat and simple solution vs,multibutton universal monster

 

[metal]

let me think about it, but bear in mind it is a bit late at this phase.

 

[jean-paul]

What remote did you have in mind then ? The Apple Remote is only 20 Euro when ordered straight from Apple.

 

[metal]

I prefer Sony RM-X151 because I have been planning to use it in other projects, I have already ordered two of them and I am writing code for SIRC, I am not much into Apple products and not willing to order this remote in the near future, sorry Jean.

 

[Rudi_Ratlos]

I myself am using the ones shown on the image attached. Both of them "talk RC5".

BillyK has agreed to check my BoM. Thank you very much,Billy.🙂

Concerning the additional PCB (HomeTheatre Bypass, SoftPowerOn and DIL-to-SIL Adapter):I have asked the etching company,
if they support perforated PCBs or if they will do 3 additional cuts.
I have not yet received an answer.

Best regards - Rudi_Ratlos

 

[voxxonline]

At least sony is small and has less buttons , to me it is a great benefit.

 

[voxxonline]

Guys, how close components can be inside power amp... 2 amp boards , 2 traffos and if I put pre close to rectifiers of both pcb's , and near the traffos...
I d like to go integrated approach but it depends 🙂

P.S. Rudi what is a height of board with traffo you use?

 

[Rudi_Ratlos]

Jean-Paul, I assume that your torroid will hardly fit! Shown is a circle with a diameter of 42 mm.
I have done a more flexible layout for the transformer, in case somebody uses a 2x115 VAC primary and/or 2 x ? VAC secondary transformer.

Voxxonline: the transformer is the highest part; its height is 41 mm.

Best regards - Rudi_Ratlos

 

[Rudi_Ratlos]

Gentlemen: find attached an image of my VCPre - prototype, playing / attenuating a CDP's track with a 1KHz sine wave on it.

The attenuated sine wave looks perfectly on the oscilloscope! Despite the vicinity of the RCA-connectors, relay, ... to the transformer.
So please don't argue anymore.

Best regards - Rudi_Ratlos

 

[jean-paul]

No more arguing Rudi but you should measure hum without input signal IMO.

 

[wirewiggler]

Rudi,
That leaves the only legitimate argument, when can we get one?

Bill

 

[Rudi_Ratlos]

Bill, I have prepared a small EXCEL and will collect the names of all participants into it.

I will keep the group-buy open for about 2 weeks.
Then I will order the PCBs and parts.
I know from experience that the delivery of the PCBs will take about 3 weeks.
So the question to your answer is: you will have the parts by end of July.

Best regards - Rudi_Ratlos

 

[jean-paul]

Any chance for getting the PCB set together with matched LDRs ? Don't know otherwise where to find those.