Yamaha DTXpress/DTXplorer/DTXtreme

Hi,

I'm thinking about making a dtxpander circuit for a brain inputs 6 and 7, by connecting a  
trigger to the stero PCY65S's. Some time ago, Keith wrote that just a few extra 
components are necessary to do just that, but the problem is I don't know how the 3 
different signals ("rim1", "rim2", main) can run through a stereo (2 signal) cable (similarly, 
how this works for the TP65S in input 2 is a puzzle). The only option I can think of is that, 
in terms of the jack, for example main gives signal to the tip, "rim1" only gives a signal to 
the part below the tip, "rim2" gives signal to both...? But how to build a circuit for that? 
Keith? anyone?

 Btw the two circuits that I have been able to solder are for normal stereo pads. They work 
well only if I omit diode D2 from the circuit (as suggested by others) which is connected to 
a Pintech Concertcast. Also mentioned by others and working best for me is reducing R1 
to as low as possible values for increased sensitivity of the "rim pad". 

Erik Paul

--- In DTXpress@yahoogroups.com, "epvk_jahoe" <yahoo@e...> wrote:
>
> Hi,
> 
> I'm thinking about making a dtxpander circuit for a brain inputs 6
and 7, by connecting a  
> trigger to the stero PCY65S's. Some time ago, Keith wrote that just
a few extra 
> components are necessary to do just that, but the problem is I don't
know how the 3 
> different signals ("rim1", "rim2", main) can run through a stereo (2
signal) cable (similarly, 
> how this works for the TP65S in input 2 is a puzzle). 

Erik,

The piezo signal always goes to the tip of the connector.  The ring is
connected to the rim FSR.  To get two rim shots, a 10k ohm resistor is
in series with the second rim FSR.  This allows the DTXpress to detect
which rim was hit.  

You can do the same with the DTXpander - i.e. connect three pads to
one input.  I will post a modified circuit to show how you would do
that.  Basically you need two transistor circuit with a 10k resistor
in series with one.  They will both then drive the conector ring, but
being "open collector" there is no clash of signals.

Keith.

Wow, that's a quick service! Thanks a lot! 

I understand the circuit. One more thing: 
Suppose I would want to add an extra pad signal to a stero pad signal. Then, I guess one 
should 
- take J3 from the stereo pad (main = ingoing tip), with D2  to outgoing tip
-  take J1 from the stereo pad (rim = ingoing ring) and omit the circuit 'behind' J1 except 
perhaps D1, then directly to outgoing ring (if there is a signal on J1, then J3 also already 
has a signal since it's coming from the stereo pad) 
- take J4 from extra mono pad, include the circuit (top part with extra 10k) and add 
signals to outgoing rim and tip as 'usual'. 

Does that make sense? Do I pass the DIY electronics test? ;)
Thanks again!

Erik
 


--- In DTXpress@yahoogroups.com, "Keith" <keith@k...> wrote:

>
> --- In DTXpress@yahoogroups.com, "epvk_jahoe" <yahoo@e...> wrote:
> >
> > Hi,
> > 
> > I'm thinking about making a dtxpander circuit for a brain inputs 6
> and 7, by connecting a  
> > trigger to the stero PCY65S's. Some time ago, Keith wrote that just
> a few extra 
> > components are necessary to do just that, but the problem is I don't
> know how the 3 
> > different signals ("rim1", "rim2", main) can run through a stereo (2
> signal) cable (similarly, 
> > how this works for the TP65S in input 2 is a puzzle). 
> 
> Erik,
> 
> The piezo signal always goes to the tip of the connector.  The ring is
> connected to the rim FSR.  To get two rim shots, a 10k ohm resistor is
> in series with the second rim FSR.  This allows the DTXpress to detect
> which rim was hit.  
> 
> You can do the same with the DTXpander - i.e. connect three pads to
> one input.  I will post a modified circuit to show how you would do
> that.  Basically you need two transistor circuit with a 10k resistor
> in series with one.  They will both then drive the conector ring, but
> being "open collector" there is no clash of signals.
> 
> Keith.
>

--- In DTXpress@yahoogroups.com, "epvk_jahoe" <yahoo@e...> wrote:
>
> 
> 
> Wow, that's a quick service! Thanks a lot! 
> 
> I understand the circuit. One more thing: 
> Suppose I would want to add an extra pad signal to a stero pad
signal. Then, I guess one 
> should 
> - take J3 from the stereo pad (main = ingoing tip), with D2  to
outgoing tip
> -  take J1 from the stereo pad (rim = ingoing ring) and omit the
circuit 'behind' J1 except 
> perhaps D1, then directly to outgoing ring (if there is a signal on
J1, then J3 also already 
> has a signal since it's coming from the stereo pad) 
> - take J4 from extra mono pad, include the circuit (top part with
extra 10k) and add 
> signals to outgoing rim and tip as 'usual'. 
> 
> Does that make sense? Do I pass the DIY electronics test? ;)
> Thanks again!
> 

Erik,

Yes, that sounds about right.  You can miss out the odd diode on any
of the circuits, e.g. D2, but not D1 or D4.  This is because you need
 D1 and D4 to stop the main pad signal from triggering the rim, but it
is not strictly necessary to have D2 - it just balances the signals.

Also, people have found they need to tweak the values a little,
although that may only be on non-Yamaha pads/modules.  In particular,
dropping R1 and R4 to 10k makes it more sensitive to rim shots.  Also,
schottky diodes will reduce the loss through them rather than normal
diodes.

Keith.

Keith,

OK thanks again. As soon as I have some time left I'll give it a try and tell the group how it 
worked out. 

> Yes, that sounds about right.  You can miss out the odd diode on any
> of the circuits, e.g. D2, but not D1 or D4.  This is because you need
>  D1 and D4 to stop the main pad signal from triggering the rim, but it
> is not strictly necessary to have D2 - it just balances the signals.
>
> Also, people have found they need to tweak the values a little,
> although that may only be on non-Yamaha pads/modules.  In particular,
> dropping R1 and R4 to 10k makes it more sensitive to rim shots.  Also,
> schottky diodes will reduce the loss through them rather than normal
> diodes.

Yes, with my Pintech ConcertCasts I also had to reduce R1 to lower values to get 
acceptable sensitivity of the "rim" (and omit D2 for sufficient intensity of the main pad). 
Can anything be improved (sensitivity/intensity) by changing R2/R5? 

Thanks again, Erik

> Can anything be improved (sensitivity/intensity) by changing R2/R5? 

Not really.  R2/R5 are doing very little by the time you have reduced
R1/R4 to 10k.  This is the simple circuit.  The more complicated one
with opamps adds gain so can be very sensitive but then is not so
straightforward to build and needs a separate power supply.

Keith.

Hi Rob,

For a couple years now, I've used a Manhasset M48 music stand to hold 
the laptop I use with my keyboard rig.  I picked mine up at a local 
music store for around $30 to $35.  (Here's a link to the Manhasset 
web page.)

http://www.manhasset-specialty.com/stands.cfm

I rotate the sheet metal music holder (correct name is "music desk", I 
think) to horizontal with the lip at the back, and my laptop fits 
perfectly.  I had to tighten the bolt thru the pivot to accommodate 
the weight of the laptop.

The friction fit between the telescoping parts that provide the height 
adjustment isn't sufficient to support the weight of the computer, so 
I installed a small (3/4 in. diameter) stainless steel worm-drive-type 
automotive hose clamp around the upper tube right above the joint to 
hold the height adjustment.  The stand is surprisingly stable, even on 
carpet, but it might get tippy if the laptop is one of the real heavy 
ones - I think mine is 7 or 8 pounds.  If you don't feel it's stable 
enough, you might be able to exchange the base with one from a heavy 
mic stand.

Hope this works for you - Jim

--- In DTXpress@yahoogroups.com, Rob C <chanterhaus@c...> wrote:
>
> I¹m wondering if anyone has a good suggestion/solurion for a 
convenient,
> functional and sturdy laptop stand to use alongside my DTXpress set 
up?

> 
> Rob C
>

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