Group Buy (See first post): DB25 Mod for GDIY511 Rack TASCAM Analog pinout

bruce0

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So far we have about 14 cards worth of interest. 

Any ideas for letting the other 51X rack owners know about this? 

About 50 cards is the magic number where the cost per card gets reasonable.
I will post a link on the 51X support site maybe?
 

bruce0

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Ok, @Winetree and @kramerb1 you are added to the "interested" list.  I will be getting prices soon and let everyone know.  If we can get everyone that has the 51X to have a chance to play, and the more people buying, the costs will be lower.

I was going to get a price from iteadstudio, which has good prices for runs of 50.  It seems like we could have a run as short as 40 or so cards so if anyone knows another good place for prototypes let me know, and I will check it out.

Olimex (they originally did the first run) no longer do PCB's.
 

maq3396

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Sorry for the lame question...but what does the Tascam connector allow you to do?

Thanks
Mac
 

bruce0

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Perfect question, I should have explained. 

This mod:

DSC05871.jpg


allows you to connect to your 51X rack with cables like this:
...
TASCAM cable is simple a DB25 (also called a DSUB-25) 25 pin connector that is connected to 8 shielded connectors usually by a bundle of cable or via a snake. The connectors can be XLR male or female, or TRS, or the other end can be another TASCAM DB25 connector.  The DB25 pin connectors on the cable side are always male (both ends if it is TASCAM to TASCAM).

It is a quick, secure and orderly way to connect 8 balanced audio connections and not mis-cable it.  Many recorders and interfaces have these connections on them.

Here are some pictures:
DB25M10XLRM.jpg

a838fdc6396a7971c4e849f0433d49ef.jpg

aeb02e29aa43a6b81f13076263a4ea39.jpg


You can buy them from many sources at prices and qualities from no-name to mogami.  In decent cables the connections are separately shielded.

http://www.zzounds.com/item--HOSDTP80

Here is the pinout:
http://tascam.com/content/downloads/products/220/DB-25_Pinout.pdf

There are two defacto TASCAM standards, one is analog and one is digital. This is analog ( Not sure but I think the only difference is cable capacitance and cable shielding for digital cables are spec'd).
 

mulletchuck

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you can build a pair of 3-footers with Mogami Guts and Nutrik connectors for about $80 all told.  you'd pay upwards for 200+ for the same thing from Guitar Center or Sweetwater.  It takes a few hours, but it's worth it, especially if you have a cable stripper tool to speed the process of stripping 48 wires (each end of the 8chan snake)
 

bruce0

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Ok NoBass, great.  I will put you down on the list.  Thanks.

I guess I better start thinking of closing this up soon.  But things get so busy in summer.
 

bruce0

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KDE thanks, added you to the list.

I think the key thing is that people that own these 51X rack are not aware that this is available, and it takes a while for the word to spread.  Anyway, we are at a point where the cards will be priced pretty reasonably.

b
 

kvothe

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What is the estimated price on these? I would be in for 4-8 cards.
 

bruce0

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Yes, it has been a long time.  But here is what is happening.

I have been designing a routing card for the 51x rack, and to save money (and space inside the back of the rack) I have put it on the same TASCAM CARD that fits in the same place.

I have managed (almost) to route a version of the card with 9 relays on it.  You don't have to install the relays, and if you don't it will behave just like the old TASCAM card.  But if you do, then you can control those relays from a separate switch panel (A simple switch panel on a module, see http://groupdiy.com/index.php?topic=53957.msg688889#msg688889) and then the card will let you assemble virtual channel strips out of sequences of modules without patch cables.

So the TASCAM cards are still going to be available (and still at cost plus shipping), but they will have some other latent capability for routing/cascading modules, and I may put out a control module to activate it.

I did this because I have already done one of my own and I need to take out the TASCAM card to fit it in, and I didn't want to lose the TASCAM functionality.  So I made this dual purpose one.

Sorry for the delay.  Plan on ordering the cards this week with a couple more trace routing tweaks and checks.

Oh.. more good news is that it will use more commonly available DSUB-25 parts, and won't need the long standoff versions which were hard to find and cost 6 bucks apiece. 

bb

(To be clear this feature will only be activated if you build or purchase another circuit to activate the switches.  I have not built that circuit yet, just prototyped it.  I may never make boards available for it but if I don't I will show how - it is easy.)
 

kvothe

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I am still in for 4 or 8, depending on costs. The new feature is just additional awesomeness ;)
 

bruce0

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Update: Don't use these images of the cards for anything, the TASCAM connectors are upside down.  The re-layed out versions are later in the thread.

Making some progress.  Here is the layout for the new Tascam Board. 
[list type=decimal]
[*]It fits in exactly the same spot so the panel cutting template is still correct.
[*]It now uses a normal DB25 connector (many more parts will work than before)  I did this by putting the ribbon cable connectors on the back.
[*]There is now a little daughter card capability.  This card rides right behind the TASCAM card and gets all the balanced connections and ground delivered to it.

  • I have layouts for 2 daughtercards so far.
    • Cascade routing (AKA feed switches) - optionally connecting each slot to the next using relay control.
    • Mod 11 card - Module 11 can "copy" any input or any output using a rotary switch to control relays

With the Mod 11 card two cards I can audition preamps by switching from one to the next on the fly. (Attach a mic to Channel 11, monitor the output of channel 11, and then switch between multiple inputs and outputs with two rotary switches. Channel 11 provides optional 48V but mirrors the other inputs and outputs). It has to be installed in slot 11.

The Mod 11 card is on top, the TASCAM card on the bottom.  They sit close together in a stack.

CSTASC102_zps60d1f640.jpg



The Cascade card allows a 51X rack to assemble virtual channel strips (instead of patch cords but this is quicker).  Some racks have little switches on the back to chain modules together, this is the same but with relay control.

The Cascade card is on top, TASCAM card on the bottom (TASCAM Card is identical to the other photo).
RMTASC2085_zps2abb441f.jpg


I need to mock one up, make sure there are no fit problems and then I will be putting the order in.[/list]
 

KDE

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so my question is are the outputs mirrored to both the XLR and the DB25? For example could i connect the DSub outs to a summing amp and then have the xlrs go to my converter?
 

bruce0

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KDE said:
so my question is are the outputs mirrored to both the XLR and the DB25? For example could i connect the DSub outs to a summing amp and then have the xlrs go to my converter?

KDE

Thanks for the question - you need to be careful but output Y connectors don't usually have a problem, INPUT Y connectors can cause DAMAGE in some cases.  A more complete answer below.

Bruce

More complete answer:

The TASCAM is HARD WIRED to the XLR's, nothing more.  So essentially the output can be viewed as a 3 conductor "Y" cable.  Usually one output through a "Y" cable is not a problem, and in the case you mentioned it should be fine.  However be aware that you are connecting the INPUT of your summing bus to the INPUT of your converter (probably not a problem but beware unexpected effects, for instance if your summing bus is unbalanced, you will unbalance the converter connection, or one might be providing phantom power etc.)

BE CAUTIOUS using the INPUT XLR and INPUT TASCAM together.
Remember the TASCAM is HARD WIRED to the XLR's so essentially you have an INPUT Y cable. A "Y" cable.  connecting one input to two outputs can be a REALLY BAD idea, because you will be connecting the two OUTPUTS together.  Both outputs are often low impedance sources and they will try to drive each other.  This can damage them multiple ways, including but not limited to the output amp trying to drive a really low impedance (frying, etc) or the output amp not being engineered handle input currents etc. 


 

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