chipss36

Re: Access-312 Build Thread
« Reply #560 on: March 11, 2018, 07:43:28 PM »
Yes it’s the power supply many used , and has a dead link on the first page.

I have the board but zero info on it.
« Last Edit: March 12, 2018, 12:30:16 AM by chipss36 »


Whoops

Re: Access-312 Build Thread
« Reply #561 on: March 12, 2018, 04:52:16 PM »
That PSU is long gone and it was just a sugestion at that time.

Don't worry about it,
you can use any 3 rail PSU.
You need +16V, -16V and +48V for the phantom power

You can buy this one with "extra aux rail" option:

https://pcbgrinder.com/POWER-SUPPLY-PSU-LM317-LM337





chipss36

Re: Access-312 Build Thread
« Reply #562 on: March 12, 2018, 05:56:08 PM »
 Buying another is an option but was not the question asked.
Just saying.
Still looking for documentation on the psunaversal power supply.
Thanks.

bxt403

Access-312 board for API 325 line amplifier (or equivalent)
« Reply #563 on: April 03, 2018, 08:15:39 PM »
I noticed that the Access 312 board can be converted to into a 325 circuit fairly easily (after some component value changes and removing the input transformer). This is useful when you  want a pair to be used for stereo signals (where the gain switch for two modules is a double pole type: one pole per module)

I've cross-referenced with the API 325 manual's "Line or Booster Amplifier" section and it looks like the 325 has "Open" for a 6dB minimum and maximum value of  42dB @ 240 Ohm (for the column that corresponds to the output transformer's wired as two windings in series like it is on the Access 312).  That means (for those who might want to wire a pair of  Access 312s as a pair of 325s for stereo signals and since a double pole 2 throw switch is easier to wire than a 9 to 12 pole one):  12dB = 39K Ohm,  18 dB = 13K Ohm, and 24dB = 5.6 K Ohm). 

The components that change are all the ones from the signal input to the transformer input.  Everything related to the +/- 16 to 20 Volt power input can be left the way it originally is on the Access 312 schematic (although you might want to increase the two 35V electrolytic capacitors to around 50V if you intend on supplying +/-20V to the modules).

 




« Last Edit: April 14, 2018, 09:29:06 PM by bxt403 »

3nity

Re: Access-312 Build Thread
« Reply #564 on: May 26, 2018, 10:36:29 PM »
Bxt403.
In fact I used a 312 PCB stuffed parts like a 325 for a poor man eq gain stage..works perfectly.

Life is a path, death the destination.

Le Roux

Re: Access-312 Build Thread
« Reply #565 on: July 15, 2018, 04:37:33 PM »
Thought I'd add a pic of my 4 channel build

Love this preamp!

3nity

Re: Access-312 Build Thread
« Reply #566 on: July 15, 2018, 10:30:34 PM »
Nice build.
Love the vertical mounting of the boards.
The di is the Bo Hansen?

Cheers.
Life is a path, death the destination.

Le Roux

Re: Access-312 Build Thread
« Reply #567 on: July 16, 2018, 04:08:17 PM »
DI is JLM

Bo Hansen would have been awesome! Totally forgot about that project!

Re: Access-312 Build Thread
« Reply #568 on: January 08, 2019, 08:57:09 PM »
OK, so: I've purchased the boards, BOMs, XLR jacks, pots, knobs, buttons, screw terminals, and even an external PSU (the Collective Cases one mentioned earlier in this thread). I have my EA xformers and DOA kits from CAPI. I also have a decent amount of soldering experience and even a little time working around mains voltage thanks to about five years of guitar pedal and mic builds (including a tube one that involved swapping out a PSU board).  I feel like I'm MOSTLY ready to do this thing. That said, I wanted to reach out to the DIY community and see if y'all could help me with a couple things:

1) Star ground: I've just never done it. Ideally, I'd just like some up-close-and-personal photos showing what it's supposed to look like and how people have tended to wire it. I understand the general principle, have read up on how it usually works in an amplifier (i.e. connecting a wire from the IEC to the chassis), and have even gone through the Whistle Rock ML12  PSU docs (which located star ground on the ML12 PSU PCB itself - and, sadly, seem also to have disappeared from the internet), but I would love a clear photo and diagram that shows how it should play out in this particular build. Note: I HAVE LOOKED AT OTHER THREADS TO TRY TO FIGURE THIS OUT. Hell, maybe I HAVE figured this out and am just being overly cautious. But my dumb questions include:

+ Should I star ground power and signal paths separately?

+ Wiring-wise, should I ground by soldering ground connections to a central point that's attached to the chassis - that is, use a lug terminal screwed to the chassis and solder wires to it? Or  should I attach lug terminals to my various ground wires and screw them tightly against the chassis? Is either consider best practice?

Again, I recognize that these are somewhat esoteric questions and there likely isn't just one way to do it, but I want to get it right the first time! Grounding issues have been the bete noir of my DIY life, and I've become kind of neurotic about them.

2) 1U drill templates: Are they around? It seems like plenty of people have made a 4-channel version of this, and most of us want the same thing - 8 XLR punches, a star ground, and an IEC/PSU cutout on the back panel; board-spaced holes for 4 gain/P48/polarity/pad "modules" and an LED (and on/off toggle?) on the front panel. There seems to be a standard form factor for 1U chassis, too. So, that said: Has anyone made a template for the above? I recognize that I could just design one myself, but the layout thing has admittedly become the main impediment to me beginning the project - I work on computers all day, so I'm somewhat disinclined to spend a few evenings futzing with vectors and placement if I don't have to. I have actually considered picking up the Collective Cases chassis, but I already bought a Circuit Specialists 1U for this project and would prefer to just drill it and save $150+.

3) The Collective Cases PSU: Has anyone used this thing? How do you like it? Did it more or less eliminate hum? Does it obviate the need for DC filtering? And, in keeping with my first question, do I connect it to chassis ground the same way I would connect an IEC?

Any guidance on the above three concerns would be beyond welcome! This thread is already a bounty of good, useful stuff - I'm just stuck on a few things  :o

Whoops

Re: Access-312 Build Thread
« Reply #569 on: January 08, 2019, 09:09:42 PM »

1) Star ground: I've just never done it.

First thing you should do is read this thread. Thats the only thing I recomend for now.
All the info needed is here

I posted a few times a ground drawing for this project, and it's also posted on page 28, so it seems you are not reading what you should


Re: Access-312 Build Thread
« Reply #570 on: January 08, 2019, 10:12:51 PM »
First thing you should do is read this thread. Thats the only thing I recomend for now.
All the info needed is here

I posted a few times a ground drawing for this project, and it's also posted on page 28, so it seems you are not reading what you should

Cool - that covers the general wire routing, which I appreciate. However, I'm using (as mentioned) an external PSU with a 5-pin XLR jack. Its layout is:

Pin1 = SHELL:FG
Pin2 = COM
Pin3 = +16v
Pin4 = -16v
Pin5 = +48v

So, I guess the question is: what counts as 0v? Pin2/common ground? Pin1/floating ground? Both? Which would I wire/bolt to the chassis? And which would I connect to the boards? Also, do I still use the resistor/capacitor connection from the PSU to the chassis?
« Last Edit: January 08, 2019, 11:07:31 PM by vizcities »

Re: Access-312 Build Thread
« Reply #571 on: January 13, 2019, 08:58:08 PM »
Has no one used this power supply? I'd love to hear from the guy who runs Collective Cases...

Whoops

Re: Access-312 Build Thread
« Reply #572 on: January 17, 2019, 12:10:50 AM »
So, I guess the question is: what counts as 0v? Pin2/common ground?

Common is the 0v reference

Which would I wire/bolt to the chassis?

PIN1 PSU case to Chassis


Also, do I still use the resistor/capacitor connection from the PSU to the chassis?

yes resistor/capacitor from Common (0V) to Chassis,
it's exactelly the same thing as in the layout I did

Re: Access-312 Build Thread
« Reply #573 on: March 18, 2019, 10:16:20 AM »
Does anyone have a PDF (or otherwise) front panel layout for the usual 4x Access 312s that includes the F2UEE push buttons? I'm finding them excessively tricky to measure vertically in a way that feels accurate/foolproof. Part of me feels like I should just cut my losses and just use "traditional" DPDT mini switches, but the "sunk cost" part of me - along with the part that doesn't want to spend $30 on new switches - wants to make these things work.

3nity

Re: Access-312 Build Thread
« Reply #574 on: March 18, 2019, 04:06:44 PM »
Let me see if I can find a PDF or distance between each ok pushbutton.
Life is a path, death the destination.

Re: Access-312 Build Thread
« Reply #575 on: March 18, 2019, 04:20:45 PM »
Thanks! Feel free to PM me - or post here even, for future generations  ;D


 

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