Console signal flow, input cards, general discussion on API styled DIY mixer

[boji]

Anyone care to recommend a good 10k dual lin from a US distributor?
not finding much from mouser or digikey.

AML has
http://www.audiomaintenance.com/acatalog/SF-01-007_extended_info.html

Ebay has some sfernice for $30 ea but that's seems way expensive.

But I'd prefer to keep the costs down and do the sale stateside.

 

[jsteiger]

boji,

I got mine from Frank @ State Electronics. They are not cheap or a stock item. IIRC, I ordered 75pc and they were just under $20 each. Part number is L15449. Clarostat 388 series, dual 10K linear, center detent, solder lugs and fitted with a friction washer to tighten up the feel (still not as nice as the Bourns 50 series IMHO). 1/4" D x 1/4" long bushing. Shaft is 1/8" D x 3/8" beyond the bushing.

I slug them with 2.2K for around -4.25db when at center. Adjust to your own taste.

Best, Jeff

 

[boji]

My man. Appreciate the suggestion. Pricey tho!

They also have these:
http://www.potentiometer.com/series388.cfm?session_num=2010062616362948
which look a helluvalot like a bourns with a 'state' label. They even curl the pins like the 50 series.

The AML's are ~$14 plus VAT and ship. I'm guessing that's less than state in the end, but the clarostats I imagine are a superior pot...

 

[jsteiger]

...They also have these:
http://www.potentiometer.com/series388.cfm?session_num=2010062616362948
which look a helluvalot like a bourns with a 'state' label. They even curl the pins like the 50 series.

Those are the same ones I got boji. Clarostat 388 series. They don't feel as good as the Bourns. That's why I had them add the friction washer. They are matched pretty well. They pre-match the decks before building them. That spec should be tied to that part number I gave you.

The AML's are ~$14 plus VAT and ship. I'm guessing that's less than state in the end, but the clarostats I imagine are a superior pot...

Well, Colin won't charge you VAT but your CC company will ding you a little for the currency conversion. Minimal though. Shipping won't be too bad really. I can only say that the old pan pots that I replaced in my console were Vishay/Sfernice. They were not originals and I don't know how old they were. They turned like shit though. Very stiff and grindy feeling. Made you wanna reach for pliers. The "tech" who worked on the board for the previous owner ordered them custom as they were dual-concentric with the "level" control. He messed up and they came with the pan on the top, level on the bottom. He of course used them anyhow. Kinda irritating to me. Anyhow, I removed the 1K level control as I did not see a need for it there.

Make sure the shaft and bushing are what you need for the knobs & faceplates you are gonna use. The shaft looks pretty short on those from Colin. You may want to get one to check it out before ordering a small boat load. I sound like a broken record! 

Oh, my slug R is 2.21K, not 2.2K but I'm sure there is very little dif.

I did get my P&G's from Colin, BTW.

Best, Jeff

 

[fazer]

Those pots from Audio maintenance are what we order at Rocky Mountain Recorders for the Amek Motzart.  There good but the way they mount in the console creates a failure in the pot on various channels.  The PC Card has them soldered direct to the card.  The top face plate pulls on the pot from the top where the nut mounts and the pot is pulled away from the pc card causing the track on the pot to break.  Tighten by hand with the special drivers.  Do not use a drill because it can over tighten the pot and break. 

I have had numerous broken pots on Rocky's Amek console.  If your building with pots soldered into the card be careful that the pot has proper washers for spacers.  Also order the Tools for the nuts that mount the pots.  The slot nuts used to mount these require a hollow shaft nut driver.  Just order it.  Standard nut drivers do not have enough space for concentric shafts if you use those.

 

[boji]

Hey fazer, thanks for the heads up.

 

[fazer]

Tools look like this.  well worth it if you have a lot of pots to mount.

The back handles are for the knobs .  you may not need those .  Metal are for the Pots and nuts.

 

[boji]

Must I use a polarized cap in every case where the schematic asks for one? On the schema there is a 1uf 50v who's symbol is clearly referencing a polarized lytic,  but WIMA has a nice nonpolar 63v 5% @1uf.
The cap I'm talking about is near the + lead of A2, signal after the HP caps.
Is it required to be polarized due to its size? The rule is to avoid lytics whenever possible, so I suppose that's the reason I ask. If I could use a poly there I would...

http://www.mouser.com/ProductDetail/WIMA/MKS2-1-63-5T/?qs=sGAEpiMZZMvOcEq4GH1AApISu39GQuPNrHPZfaTFZMc%3d

 

[fazer]

Boji - that link brings up a .1uf cap.  check your size for a 1uf cap.  Also the poly I believe would work fine.  I also use non polar caps in the 1uf size in guitar pedals because they sound better to my ears.    If your looking for authentic , you would dup everything.

 

[fazer]

Sorry my bad.  I see the 1uf down in the list for size.

 

[Junction]

Skiz asks for 10v cap. Can I bump to 50v without issue?

Yes no problem, you can always go up in Voltage rating but no go down.
Michael

 

[boji]

Any problem using a 1000v cap here? Or just stick with a COG?

68pf    1000v    5%    wima
http://www.mouser.com/ProductDetail/WIMA/FKP2-68-1000-5/?qs=sGAEpiMZZMsh%252b1woXyUXj1f8f4DD4vmEb6yQZUgm2M4%3d

 

[jsteiger]

Boji,

It's just in the feedback loop so I use a BC Mono-Kap that is 68pF/50V. It is c0g with a 2.54mm lead spacing. Mouser and Digi both have them. I think Mouser is cheaper as usual. Search for K680J15C0GF5TL2.

Cheers, Jeff

 

[Nickos]

Hi all,
I would like to resume this thread because I'm doing something similar nowadays.
What I want to build is a modular, line-only channel for use with API 7800 Master Module.
It's a "light" version of what it's been done here.
It has:
- Balanced Line receiver
- Fader
- Pan
- 4 Aux (pre-post)
- 4 Bus + Stereo Bus
- Solo Bus & Logic
- Optional transformer direct out

It's a preliminar design, I have to check all components and values.

I have a doubt about the 7800 busses, hope someone can help me: on the manual the pinout show + and - for each bus. They use balanced mixer busses? it seem strange to me...  ???
Here there's a link of the 7600 Input Channel, it shows the pinout and the block diagram. http://www.apiaudio.com/man7600.pdf

Thank you,

Nickos

 

[fazer]

Nickos,  On my API 2488 , the bus out is unbalanced from the fader of the channels.  These are taken before the channel direct out transformers and since the bus runs on a PC card track under the input modules, the bus is shielded with the alum frame of the console. 

The 7800 is external with cables and maybe they decided to balance the interconnect for more noise immunity. 

 

[Nickos]

Nickos,  On my API 2488 , the bus out is unbalanced from the fader of the channels.  These are taken before the channel direct out transformers and since the bus runs on a PC card track under the input modules, the bus is shielded with the alum frame of the console. 

The 7800 is external with cables and maybe they decided to balance the interconnect for more noise immunity.   

It make sense  :-\
It could be a bad news for me because this project can be too large with 10 more balanced lines...
Anyone can confirm this? Unfortunately I can't access any 7600,8200 or 7800 yet...

 

[boji]

So Nickos, what did you decide to do? Perhaps you can keep your mixer unbalanced, and bypass the line receivers in the 7800, going direct to the ACA within it...

BTW I plan on resurrecting this thread; I'm finding a little time to come back to this project. Currently I'm relearning everything I did last year, and going over signal flow of my schematics. I already found some mistakes I missed before, so that's good!

Something else of issue, I'm using lit switches where one of the poles is dedicated to led gnd.  That leaves me three poles for a send bypass*.
Since signal is coming from (depending on the mic/line switch) either from a line driven 2623 TX, or a slot 1 Mic pre TX,  the signal will be balanced. With the 3 available poles on the switch I can drop the Cold and Hot of the send entirely but only half of the return (see picture), or all of the return and half the send. What I'd like to know which is the better solution or if there is an even better solution I have not imagined? 

*(Is the need for a bypass switch silly? I'm just thinking I'd rather not have the sends ALWAYS run out of the input cards, down six-ish feet of the mixer to the patch panel, normalled loopback to run all the way back to the input cards. I mean I want the option to insert stuff, but I'd also like to bypass all that wire whenever possible. If I don't need an insert, the hard bypass would keep the signal inches from the tx of slot 1 to the input of slot 2.)

 

[abbey road d enfer]

Something else of issue, I'm using lit switches where one of the poles is dedicated to led gnd.  That leaves me three poles for a send bypass*.
Since signal is coming from (depending on the mic/line switch) either from a line driven 2623 TX, or a slot 1 Mic pre TX,  the signal will be balanced. With the 3 available poles on the switch I can drop the Cold and Hot of the send entirely but only half of the return (see picture), or all of the return and half the send. What I'd like to know which is the better solution or if there is an even better solution I have not imagined?

You have to do it right or not do it. Either use 6-pole switches or leave the insert send permanently on.

*(Is the need for a bypass switch silly?

I wouldn't say silly, but a tad overzealous. Like full-normalled patchbay sends.

 

[boji]

You have to do it right or not do it. Either use 6-pole switches or leave the insert send permanently on.

I've been properly chastised.
I likes the look and feel of wellbuying's backlit switches you see on fivefish's pre's. I don't think they make them in 6 pole tho.
Now that I think of it, I could use a 2 pole and...arg...another relay...

 

[fazer]

gold contact hermetic sealed.  less wire shorter path.  it starts to look like a mastering console switcher.