Finished my pre-amp
I finished my little pre-amp based on the VC23 of Hifimediy yesterday. Some time ago I built a small/simple pre-amp with rotary switches and 2 opamps, but as one channel broke, I decided I wanted remote control as well.
So I took out the old board an replaced with the VC23 board. Two pictures attached (hope pictures are not too large).
As you see, I made a mod to one of the power connectors (the other one was too tight). The PCB fits in a standard eurocard case, however due to the placement of the power terminals you can't easily slide it into one of those boxes.
In the picture below the preamp is the power supply delivering 15-0-15 V dc(!). The two boxes on either side are gainclones/chipamps based on the LM3875
Initial listening confirms that this amp is an improvement over my previous pre amp. Not so much the sound quality, that was already very good, but ease of use is fantastic.
Some other remarks:
Above comments not meant to be too critical, but maybe they help to improve the product.
regards,
Maarten
I finished my little pre-amp based on the VC23 of Hifimediy yesterday. Some time ago I built a small/simple pre-amp with rotary switches and 2 opamps, but as one channel broke, I decided I wanted remote control as well.
So I took out the old board an replaced with the VC23 board. Two pictures attached (hope pictures are not too large).
An externally hosted image should be here but it was not working when we last tested it.
As you see, I made a mod to one of the power connectors (the other one was too tight). The PCB fits in a standard eurocard case, however due to the placement of the power terminals you can't easily slide it into one of those boxes.
An externally hosted image should be here but it was not working when we last tested it.
In the picture below the preamp is the power supply delivering 15-0-15 V dc(!). The two boxes on either side are gainclones/chipamps based on the LM3875
An externally hosted image should be here but it was not working when we last tested it.
Initial listening confirms that this amp is an improvement over my previous pre amp. Not so much the sound quality, that was already very good, but ease of use is fantastic.
Some other remarks:
- I think Hifimediy should include some sort of short manual. Of course lot's of material can be found on the forum, but it's no substitute. Also the website does not contain such documents for download.
- There is no list of parts that are or should be in the box. So it is hard to say whether or not you received all components.
- Only two connecting cables are included. Since it has one output and 4 inputs, this is not enough. Are the others missing, or should I buy the others myself
- Both of the Opamps were dropping out of their sockets as they were fitted too loose.
Above comments not meant to be too critical, but maybe they help to improve the product.
regards,
Maarten
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AC or DC?
Maarten: How is it you are able to use 15-0-15 VDC?
I powered mine up and got a horribly loud 60Hz buzz and the amplifier wasn't even turned on. I used one leg of the 12.6-0-12.6 VAC for the digital circuit.
Agreed, some instructions should be included. Does the board need to be grounded?
Maarten: How is it you are able to use 15-0-15 VDC?
I powered mine up and got a horribly loud 60Hz buzz and the amplifier wasn't even turned on. I used one leg of the 12.6-0-12.6 VAC for the digital circuit.
Agreed, some instructions should be included. Does the board need to be grounded?
i just happened to have the 15-0-15 Vdc power supply. i figured that 12Vac would probably result in 17vdc after rectification, so 15Vdc would probably still be Ok. On the picture you can see the wiring (red/red and green/blue) are same.
i did not ground the amp itself, but looking at my documentation of the ps the black (0vdc) wire is probably connected to safety earth somewhere inside the ps (have to check)
Maarten
VC23 build photos
Here are some pics, still trying to figure out the buzz... Switched the digital input to 15 VDC and still had the buzz, then a 2nd tone started and was getting louder very quickly. Does the polarity matter on the digital input?
Here are some pics, still trying to figure out the buzz... Switched the digital input to 15 VDC and still had the buzz, then a 2nd tone started and was getting louder very quickly. Does the polarity matter on the digital input?
Attachments
Hi, IBM5150, when your system use not only VC23 boards, I suggest test each board separately, that will more easy to find what's the problem.
And I also suggest use a standalone power supply for the digital part of VC23, and VC23 already has a (analog and digital)ground junction itself on board.
And I also suggest use a standalone power supply for the digital part of VC23, and VC23 already has a (analog and digital)ground junction itself on board.
Have removed the MiniDSP from the setup, and taken the board out of the case. Now have 15VDC on digital channel, 12.6-0-12.6 on AC connector. I think the buzz is a grounding issue, but there is another problem - the output is very very low. I can just barely hear a signal at -15, turning it up louder it is very distorted. I only have channel 1 connected, and switching channels cuts the sound out completely. Ideas?
Thanks again.
Eric
Thanks again.
Eric
It's all good now, thanks to a good friend/lab tech at work. I must have had some bad solder joints. He swapped out the signal connectors on the board with a 3 pin PC fan looking connector and the mating connector, terminals and crimper, then used new shielded signal wire to the RCA's. No more buzz, nice clear signal, remote and everything works. Enjoying it!!! Thanks for your prompt replies and the nice product.
Best Regards, Eric
Best Regards, Eric
- Only two connecting cables are included. Since it has one output and 4 inputs, this is not enough. Are the others missing, or should I buy the others myself
Today I received 3 additional connecting cables from Steinar.
Thanks for the great support!
Maarten
I was made aware that there was an virus on the site that redirected all traffic to a russian fake internet security site. I immediately contacted my host provided, which deleted the virus and I update the software. I discovered that the link to the internet site still remained after this, so i needed to clear browser data (cookies) from my local browser to be able to get back to the real site. I recommend everyone to do the same.
Sorry about this, and hope this didn't cause any additional problems to any of you. Scary how this can happen.
Steinar
EDIT: It seems that it still not completely removed, I'll work with my provider to clean this up.
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I am very interested in the VC43 board mentioned a few pages ago..
I have a miniDSP 2x8 and want to control the volume after the output of the board so that there is no digital attenuation of the signal. I also want to be able to switch inputs and volume from a remote.
Can you give us more details of the specification of the new board? Perhaps some input on what would be desirable?
In the long term, I would like to have two of these. One to control the 8 outputs of my miniDSP (front channels) and one to control the output of the surround channels from either a media PC or blu-ray player with analogue outputs. In this scenario can you see a way of controlling the volume of each channel on two boards? ie, controlling 16 channels volume up and down at once from a single remote?
I want to build a nice stereo system, but also like the idea of later being able to control the volume of surround sound for my living room.
Many thanks.
Jai Stanley
I have a miniDSP 2x8 and want to control the volume after the output of the board so that there is no digital attenuation of the signal. I also want to be able to switch inputs and volume from a remote.
Can you give us more details of the specification of the new board? Perhaps some input on what would be desirable?
In the long term, I would like to have two of these. One to control the 8 outputs of my miniDSP (front channels) and one to control the output of the surround channels from either a media PC or blu-ray player with analogue outputs. In this scenario can you see a way of controlling the volume of each channel on two boards? ie, controlling 16 channels volume up and down at once from a single remote?
I want to build a nice stereo system, but also like the idea of later being able to control the volume of surround sound for my living room.
Many thanks.
Jai Stanley
hi, Jai
VC43 is ready here, but I think it's need some time to go ON Stock.
VC43 control up to 8 channel volume, it also can control volume of 1+5, 2+6, 3+7, 4+8 channel separately. And other functions are almost same as VC23.
The board can accept almost all analog source, it have good OP buffers before the PGA4311 chips.
I think it's ok to control 2x unit when you put the front panels together.
VC43 is ready here, but I think it's need some time to go ON Stock.
VC43 control up to 8 channel volume, it also can control volume of 1+5, 2+6, 3+7, 4+8 channel separately. And other functions are almost same as VC23.
The board can accept almost all analog source, it have good OP buffers before the PGA4311 chips.
I think it's ok to control 2x unit when you put the front panels together.
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