dcx2496 shakedown

[AndrewT]

Hi,
I have wired in -32db of attenuation in the output from the DCX.
Feeding a very short wire (15mm) into each of the Michell power amps(+33.3db), then into Acoustic Energy AE1s.
I can turn off the source and let my ears acclimatise to the lack of noise and when putting my ear to either the treble unit or the mid/bass the output is completely silent.
When these speakers are passively connected to a Cyrus 8 (+34.4db) they emit a slight hiss but this appears silent at 500mm.
Conclusion;- run the input into the DCX to just below clipping and then attenuate the output to achieve complete silence when required.

[ultrachrome]

Davey,

For the output cables, are you saying use diagram 4B (1=shield 2=red 3=nc)? If so, the shield is connected to the RCA?

[thylantyr]

I messing you with





When people saw the Ebay listing, many had this look on their face ->

But he did lure a buyer and the buyer knew it wasn't a mac.

****

Back on topic, what is the lure to use the Rane over the Behringer? The Rane cost 4x more? Is it 4x better?

[ultrachrome]

I think the guy with the singing polar bear avatar mentioned it a while back. A big plus is that it has a built in volume control that can be controlled by wiring up a linear pot and for some reason I got the notion that it supported unbalanced signals better than the Behringer and may even sound better.

There seems to be a lot of confusion about using the Behringer with normal home equipment. I have yet to find a clearly stated answer to what seem to be the most common question: how to use with unbalanced RCA connections. I'm hoping Davey comes back and answers my last post with "Yes."

[ultrachrome]

I was wrong about that avatar. Here are the comments I've read:
sfdoddsy
Thunau

There's another user who posted in the big DCX2496 thread that he had received the Rane on loand but he never posted his findings.

On the issue of volume control, having remote volume control is necessary for me. I hate having to get up to change the volume. I currently using relay volume controls in my two preamps and they were both about $100-150 each.

The idea of using three of these to control volume seems like too much of a pain and cost/complexity-wise seems high when compared to the Rane that could conceivably act as a preamp, crossover, parametric EQ, and volume control all in one box. I'd still have to make a remote linear pot to control volume but I think I could just modify one of my remote volume boards to do that easily enough.

[thylantyr]

On the issue of volume control, having remote volume control is necessary for me. I hate having to get up to change the volume.

So essentially you are spending an additional $700 for the Rane
just to have that pot feature. // ouch //

If you didn't need the remote volume, then I bet I can make
your loudpeaker work with the $120 Behringer analog crossover
but you want dipole and probably want some form of eq. // hehe // ..

[ultrachrome]

Not really. Seems like the Rane is more the equivalent of a DEQ+DCX.
MSRP comparision is DEQ+DCX $600 v. RPM 26z $1000.

It's not the cheapest way go but it seems like the Rane holds the middle ground between the Behringer and DEQX solutions.

[ThorstenL]

Konnichiwa,

Originally posted by ultrachrome
I made a simple rca to XLR cable by bridging pins 1 and 3 per the Behringer manual (p20).

While general practice in Pro-Audio this is a terrible idea.

It actually makes one of the two halves of the output op-amp work into a very low load (60 Ohm) which causes it to thermally modulate the common die with signal and to modulate the common supply.

As you also need around 20db attenuation to interface the DCX to consumer standard Amp's, here is my suggestion for a "Balanced/SE" attenuating converter that does not cause the above problems and does not require a transformer (which is the other possibility - a 4:1 stepdown studio grade line transformer with +22dbu level handeling is ideal):

Make a box with XLR "Tails" and RCA Output Cables or Sockets (depending on taste)

Each RCA output pair receives two toggle-switches, one changeover and the other center neutral. These will become switches to select between the two polarities and -18/-12/-24db attenuation.

From pin2 & pin3 connect a pair each of 2K2 (1% or better) resistors in series to pin1 (ground).

The join between the two resistors for each polarity is connected to one of the two poles of the polarity selector. Thus at the flick of a switch the polarity of any given way can be inverted.

Further the "center neutral" switch connects a 2K2 resistor (-18db) or a 750R resistor (-24db) between the two junktions of the 2K2 pairs.

Now each output Op-Amp sees a sensible load of > 2K2 each and the load is reasonably well balanced (as long as Z-Load > 10K), you can simply resolve any polarity issues (be they in different makers Amp's, drivers etc.) at the flick of a switch and your full-scale levels are now:

-12db = 2.5V RMS
-18db = 1.25V RMS
-24db = 0.625V RMS

The same thing makes a neato passive "Pro -> Consumer" interface converter in dual channels. Switch and resistor quality matter, so don't skimp too much.

Sayonara

[cmckasty]

Just wanted to thank all of you for your help. I have not checked the thread since my last question and was surprised at how many more posts there were. I am very gratefull for all of your collective help.


Chris M

[thylantyr]

Originally posted by ultrachrome
Not really. Seems like the Rane is more the equivalent of a DEQ+DCX.
MSRP comparision is DEQ+DCX $600 v. RPM 26z $1000.

It's not the cheapest way go but it seems like the Rane holds the middle ground between the Behringer and DEQX solutions.

Cool............

but I don't see why you need so much horsepower for your design.
I don't see any real issues with the ribbon and PR midrange that requires a fancy EQ, simple level matching will do the job. The EQ you need for the dipole, does it require an expensive solution ? /hehe
You would think that even one parametric band is sufficient..... the
net result is an expensive volume control for your application. /heh