Mic connection: to Scope card or to Luna 2496 I/O interface?

[CreamWare4Ever]

Hello,

I have a Scope 3 DSP card and its original 8 channels interface. I want to connect a microphone through a mic preamp. Now I'm wondering if it is matter to which one I connect the microphone: To Scope card input jack, or shall I connect to its I/O interface?

I red somewhere that I should possible avoid to connect to Scope card input jack because of some power difference on PCI card - because that can possibly have some impact on sound quality.

That doesn't make so much sense because the people that don't have attached I/O interface must use Scope cards on board.

But maybe they meant that IF, only IF, 8 channels I/O interface is attached - then I should use it instead of Scope on board one?! Confused :puh:

Any idea?

[dante]

Well, currently I connect the output of my Mic pre to the Pulsar analog in. At other times I have connected it to my Alesis AI3 converter then connected that via lightpipe into Scope.

I suppose the only difference would be the quality of the Digital to Analog conversion. I havent checked the specs but I dont notice much difference between the Luna analog in and the AI3 analog in.

[Cochise]

There's almost no difference; sometimes noise floor on the card input can actually be higher.
Feeding both inputs with the same signal I noticed a slight phase misalignment; I mean, the eight inputs are in phase but slightly misaligned with the onboard inputs

[CreamWare4Ever]

Thanks for your inputs people.

As 8 input interface nave RCA connectors, I felt a bit unpleasant to build a adapter that give XLR output from my mic preamp into RCA. I feels more natural to get XLR >> 1/4 jack...

Thanks.

[garyb]

either way, the connector doesn't matter. what DOES matter is the LEVEL and whether or not the signal is BALANCED or UNBALANCED.

for the most part, if the mic pre is balanced out with an xlr connector, pin 2 will be hot, pin 3 will be ground and pin 1 will be shield(there's no standard, but convention seems to follow this rule these days). if that's the case, most adaptors will connect pins 1 & 3 together and pin 2 will go to the tip of the rca or 1/4" connector and all is groovy EXCEPT if that xlr output is +4(which is normal for xlr balanced line level). in that case, you will need to lower the output level significantly in the pre in order to avoid clipping, as unbalanced connections are generally -10 or -20.

in the rare case that the xlr out is pin 3 hot, the when shield and hot come together, they short and you get no sound or low, distorted sound. in that case, you'll need to wire an adaptor cable, rewire the connector on the mic pre or use an pin2 to pin3 xlr adaptor.

there is NO difference in quality between an rca and a 1/4" connector. 1/4" connectors are a little more durable for constant repatching.

[dante]

Good point GaryB I think thats the reason I changed the mic pre output from the AI3 to the Pulsar Analog in, because the Pulsar Analog In is balanced, matching the output of my Mic pre.

[CreamWare4Ever]

Well as my mic preamp deliver balanced output signal, I will do as dante suggest.

Thanks!

[Cochise]

Be aware that 3 DSP board usually haven't got balanced input. 1/4 TRS is 2 channels: tip=>hot ch1, ring=>hot ch2, sleeve=>ground.

[CreamWare4Ever]

Be aware that 3 DSP board usually haven't got balanced input. 1/4 TRS is 2 channels: tip=>hot ch1, ring=>hot ch2, sleeve=>ground.

I couldn't find any info regarding SCOPE 3 DSP card I/O input type on sonic-core.de? If input is unbalanced isn't then easier to use 1/4 jack from mic preamp? But my mic preamp have balanced output.

In other words - I should use UNBALANCED 1/4 cable to connect my mic preamp to SCOPE 3 DSP card analog in?
Confused... !??

[Cochise]

You can find specs in the manual (appendix)

Luna specs.jpg (72.31 KiB) Viewed 3075 times

You need a balanced to unbalanced cable. My advice is XLR to RCA, using the 8 I/O external unit (Lunabox). The cold line from the balanced out has to be grounded.

patching.jpg (50.87 KiB) Viewed 3072 times

[Cochise]

Or you might use an insert cable (1/4 TRS [stereo] at one end, two 1/4 TS [mono] at the other). The stereo jack goes at the Luna input, one of the mono goes at the pre TRS output...

Or a 1/4 TS (mono) to RCA from the pre to the Luna box.

cables.jpg (81.99 KiB) Viewed 3064 times

If you set your mic-pre close to the Lunabox you can even use very short cables, which is good for analog signals, especially with unbalanced lines.