Access-312 Build Thread

[Deepdark]

This is diy you can do whatever you want the way you want it too.

It was designed that way and proven to work thousands of times before...no one ever complained...i dont see why it bothers you..

I took the decisión to use 3 separate screw conectors merely based on my design goal..

And off course it was tested...

Sorry if I sounded complaining your design. I was simply asking about the ground scheme, since all ground connections do have continuity between them, I already build one and hadn't have any trouble with it, It was simple curiosity, hope there is no hard feeling.

Regards

 

[Whoops]

This is diy you can do whatever you want the way you want it too.

It was designed that way and proven to work thousands of times before...no one ever complained...i dont see why it bothers you..

I took the decisión to use 3 separate screw conectors merely based on my design goal..

And off course it was tested...

Yes Jorge, we all know that anyone can do whatever they want.
And also you know that we like your board, it's simple, it's straight to the point it's not expensive.

Saying that,  this is a forum where we are all learning. And sharing information and advise is normally always welcome between members as you know.

You can have as many 0V connections on the PCB as you want, but only one 0V connection is needed, only one should be connected. Having 3 it's confusing to people because because new members in the DIY realm will connect 3 wires to each of the PCB 0V pads.
I just finished my 4x Access Mic Pres and before the build I re-read this complete thread, most of the builds have the 0V connection wrong, it's clearly seen in pictures, also the ground advise docs that are on the thread are not the best option as far as grounding goes,  and are actually wrong, Signal Ground shouldn't be connected to chassis directely only to 0V on the PSU, also only one connection should be made between the Preamp and the PSU. Only one connection also between PSU 0V and Chassis Ground.

My posts and Info are just to help fellow members in this build, to help also the project you created, and keep improving also the shared knowledge.
Neither Deepdark or me complained or attacked you, but the information we discussed is highly relevant to this project.

Thank you Jorge

Regards

Tiago

 

[3nity]

Sorry people.
Txts or posts dont have feelings or expresions
I was just making a point...never felt attacked or offended..neither attacking anyone.
Thanhs tiago and deepdark.

 

[Whoops]

I've built a 4 channel unit with your boards, tried it this week and sounds great.
Love these preamps, always enjoyed also the fact that is a straight to the point board.

will take some pics are post them soon

Thanks

 

[3nity]

Great.
The only goal i had in mind was a simple yet afordable high end preamp.

When you start adding relays and switches price can double really fast.

Enjoy...i want pix.

 

[hitchhiker]

I too love these boards. Thanks for doing this!

 

[dude24man]

3nity, Here's a Picture. This is my first 4 channel unit, I'm on my second as we speak. Jensen JT-110k-C, Profile 4804. Gar 2520.  Thanks for some great boards. Arthur

 

[Deepdark]

Here is the latest one I made

 

[phelar]

Hi!

I´m going to use my pair of access 312´s for gain make up. Im using a passive summing network that have a loss of -40db.
What is the best way to do this. I´m using  capi gears IT and OT and planned for a 20k rev log pot. But now i wonder...
Maybe i should use a fixed gain resistor....for the 40 db.......or go with the 20k..........or 10k?

 

[Whoops]

Hi!

I´m going to use my pair of access 312´s for gain make up. Im using a passive summing network that have a loss of -40db.
What is the best way to do this. I´m using  capi gears IT and OT and planned for a 20k rev log pot. But now i wonder...
Maybe i should use a fixed gain resistor....for the 40 db.......or go with the 20k..........or 10k?

Depends if you really want fixed gain on the preamp or if want to be able to vary the gain for future needs.

You can just use the Rev log Pot, have the Gain at Min , and in the future if you need the preamps for other needs you just bring the gain pot up.

 

[Monoteur]

Hello builders,

i'm new here and i would like to build this 4x API 312 preamp. But here are so many comments on 27 pages and on the 1st thread by "The System" are some links not working anymore. I went through every page, but didn't found some proper way to build this. I know this project is open and everyone can add things for its taste, but can someone post an "normal" 4 In/Out setup. I don't know what to do.
I don't understand electronics not so deep, but can solder very well, when you give me the right components, boards and schematics for a working 312 model for european continent. I soldered a U87i by myself and its working fantastic.

Maybe someone is so kind to sum everything up for the year 2016.

So what i found is :
the case on http://collectivecases.com/?product=access-312
the board http://collectivecases.com/?product=access-312-preamp-pcbs (but without the discrete Amp board)
the BOM http://twin-x.com/groupdiy/albums/userpics/Access-312bom-2013~0.pdf (don't know if this still working)
this mouser list, but some parts are not available anymore https://www.mouser.de/ProjectManager/ProjectDetail.aspx?AccessID=80AA125D0A
the layout by Jorge without the discrete amp schematics http://twin-x.com/groupdiy/albums/userpics/312-Layout_.pdf

If someone can collect the electronic parts, switches and pots on mouser again, many people would appreciate that, they are not so electronic heads.
Also the board schematics i found is not complete. Where is the discrete amp schematics and where do i buy the board.
I saw some versions of the preamp cases with build in power supply. I guess everybody would prefer to build this, but if its easier to buy an external one that fine too. But where for 240V?

Lots of questions and no answers. Hope someone can help me.

cheers
Mat

 

[Whoops]

Hello builders,

i'm new here and i would like to build this 4x API 312 preamp. But here are so many comments on 27 pages and on the 1st thread by "The System" are some links not working anymore. I went through every page, but didn't found some proper way to build this. I know this project is open and everyone can add things for its taste, but can someone post an "normal" 4 In/Out setup. I don't know what to do.
I don't understand electronics not so deep, but can solder very well, when you give me the right components, boards and schematics for a working 312 model for european continent. I soldered a U87i by myself and its working fantastic.

Maybe someone is so kind to sum everything up for the year 2016.

So what i found is :
the case on http://collectivecases.com/?product=access-312
the board http://collectivecases.com/?product=access-312-preamp-pcbs (but without the discrete Amp board)
the BOM http://twin-x.com/groupdiy/albums/userpics/Access-312bom-2013~0.pdf (don't know if this still working)
this mouser list, but some parts are not available anymore https://www.mouser.de/ProjectManager/ProjectDetail.aspx?AccessID=80AA125D0A
the layout by Jorge without the discrete amp schematics http://twin-x.com/groupdiy/albums/userpics/312-Layout_.pdf

If someone can collect the electronic parts, switches and pots on mouser again, many people would appreciate that, they are not so electronic heads.
Also the board schematics i found is not complete. Where is the discrete amp schematics and where do i buy the board.
I saw some versions of the preamp cases with build in power supply. I guess everybody would prefer to build this, but if its easier to buy an external one that fine too. But where for 240V?

Lots of questions and no answers. Hope someone can help me.

cheers
Mat

I don't really know how to help you.

This thread is 27 pages only, thats not a lot of pages so you should read them and probably paste the relevant info to a word doc, that way you have a compilation of what you need.

Besides that this is a really simple project, if you have problems with this project it's because you are not ready yet for this and you probably need to build other stuff first, like a guitar effects pedal or something similar.

Opamps you can buy Kits from CAPI or from the White Market Thread

You have the BOM, why dont you start by buying 4 pcb's and populate them? 
then you go from there to the PSU and wiring
Do each step at a time

 

[Spencerleehorton]

Could anyone explain how to connect the VU meter in this configure please?

Regards

Spenc.

 

[Whoops]

Could anyone explain how to connect the VU meter in this configure please?

Regards

Spenc.

The output transformer has an isolated secondary that people use to feed a VU meter. On the Access pcb you have already pads on the board for the VU feed output

 

[Spencerleehorton]

Hi whoops,

So just do I need diode bridge then attach to VU meter? Or do I need a VU meter driver?
And what VU meter can I attach?

Regards

Spence.

 

[Spencerleehorton]

Not using the output txf I'm using the line balancer IC, so I probably will need a VU meter driver right?

Regards

Spence.

 

[Harpo]

The output transformer has an isolated secondary that people use to feed a VU meter. On the Access pcb you have already pads on the board for the VU feed output

...and with the output transformer connected as shown in the schematic (two secondary windings connected in series=+6dB), the 3rd. secondary winding for the VU-meter will show half level of the audio output. If your VU-meter is a real VU-meter (electro-mechanical device with internal rectifier), there will be a 3K9 resistor to be inserted in series to this VU-meter.

 

[Whoops]

Not using the output txf I'm using the line balancer IC, so I probably will need a VU meter driver right?

Regards

Spence.

I guess so, but I never done that

 

[Spencerleehorton]

i'm looking for a simple but good way of introducing VU meter to pre amps, is a VU meter driver circuit worth looking at using a TL072?  or is there a better option?

regards

Spence.

 

[Whoops]

i'm looking for a simple but good way of introducing VU meter to pre amps, is a VU meter driver circuit worth looking at using a TL072?  or is there a better option?

regards

Spence.

Maybe you can check how it's done in the Green Pre and also in the SSL9K5