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Old 23rd March 2015, 01:46 PM   #771
Rudi_Ratlos is offline Rudi_Ratlos  Germany
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I am very happy that METAL is "on board" again!

Together we will get rid of the motorized analog dual-potentiometer (which is imprecise, costs a lot, ...is an anachronism) and will replace it by a laser-trimmed dual digital MCP42100 potentiometer (being followed by a VCCS).
The MCP42100 will give you 256 (!) wiper steps for both inline potentiometers!

I have attached two images of our current progress.
We are working hard on it!

Be sure: this will be one of the best-sounding, very well-priced and versatile PREs that you have ever listened to!

It will take some time though. Neither METAL nor me are in a hurry.

Best regards - Rudi_Ratlos

P.S.: The software (the PIC's firmware) to be programmed (will be done by METAL) is the biggest part for a successful implementation!
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File Type: png MCP42100_1.PNG (64.3 KB, 193 views)
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Old 23rd March 2015, 01:54 PM   #772
atupi is offline atupi  Romania
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This is great news Rudi! I have a proposal and a question. The proposal is to put also two switch to be able to adjust volume manually not only from remote control.
This digital pot will be like a retrofit module for the old preamps or will be a completely new version of preamp with relays and everything ?
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Old 23rd March 2015, 02:11 PM   #773
Rudi_Ratlos is offline Rudi_Ratlos  Germany
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Adrian: there will be no knobs neither switches on the front-panel of my SYMASYM's case!

I like to sit in my armchair and do everything via remote-control!

The "new R_PRE-PCB" will no longer support an analog motorized potentiometer with Motor- H-bridge.
We have entered the 3rd millenium - didn't we?

Kind regards - Rudi_Ratlos
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Last edited by Rudi_Ratlos; 23rd March 2015 at 02:13 PM.
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Old 23rd March 2015, 02:14 PM   #774
atupi is offline atupi  Romania
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Sometimes remote controls likes to play hide and seek with theirs owners
It will be a completely redesigned preamp module with digital pot ?
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Old 23rd March 2015, 04:11 PM   #775
redjr is offline redjr  United States
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Quote:
Originally Posted by Rudi_Ratlos View Post
....But since the VCPre (its LDRs) is not able to drive a long pair of RCA-cables and (or) a low-impedance amplifier, I decided to connect the VCPre's output to a buffer.
I have chosen Calvin's buffer.....
I know I was late to the VCPre party, but I had much bigger projects to deal with over the past 18 months. And since I'm slow and meticulous, and still work full-time, it takes me many, many evenings and weekends to complete a project.

So, what exactly is the difference between a pre-amp and a buffer? Or, are they essentially the same? I gather from reading they are the same. I don't have long interconnects between my gear so would the VCPre be enough of a pre-amp to use. BTW, I built the Doug Self preamp a couple of years ago when it was featured in Elektor, which I use in my main system, but I have other amps where I want to use the VCPre.

I've read much on the B1 Buffer Salas and have order the PCB for it along with the parts. Could I use the VCPre to feed the B1 buffer like you did with the Calvin? Are there any benefits of doing so aside from allowing longer RCA interconnect runs? I would still use the VCPre as the signal switcher over the manual method used on the B1.

My next big project is your Symasym amp with the newest digital pre as an integrated amp. Would this be a good project to incorporate the B1 Buffer? I will start on the Black Beauty PCB soon.

Thanks for all you hard work on these projects!

Rick
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Old 23rd March 2015, 04:17 PM   #776
atupi is offline atupi  Romania
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VcPre is basically an attenuator+source selection module. Of course you can add a Calvin or a B1 for easier driving. Both Calvin or B1 are buffers meaning they are not amplifying or attenuating just matching impedances.
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Old 23rd March 2015, 08:30 PM   #777
metal is offline metal  Jordan
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Here is what I 've got for you today, more later :- )
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Old 24th March 2015, 02:10 AM   #778
redjr is offline redjr  United States
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Default Motorized VC

Is the motorized volume control designed to be used manually as well? If so, does it need to be energized? I tried to manually rotate the shaft on one of Bourns I got for the VCPCre and it's very, very stiff. Near impossible to move, or move smoothly for sure. Does energizing it free up the gears or something?
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Old 24th March 2015, 03:27 AM   #779
atupi is offline atupi  Romania
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Should move freely even manually. Maybe your pot is broken or something enteren into mechanism.


Sent from my iPad using Tapatalk
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Old 24th March 2015, 12:09 PM   #780
redjr is offline redjr  United States
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Quote:
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Should move freely even manually. Maybe your pot is broken or something enteren into mechanism.


Sent from my iPad using Tapatalk
They've been in the plastic bags since I got them over a year ago. Hum... I'll check the other one. They move anything but freely.
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