linuxaudio.org

On 01/07/2012 01:05 AM, linux-audio-user-request@lists.linuxaudio.org wrote:

quoted text
> On Fri, Jan 06, 2012 at 10:50:12AM -0500, Chris Metzler wrote:

>> >  1.  Some PCI interfaces (like the Delta 1010LT) have RCA jacks rather

>> >  than 1/4".  What about issues relating to noise/degradation introduced

>> >  by a 1/4"-to-RCA adapter?  I've read elsewhere (on the M-Audio forums)

>> >  of people complaining about unpleasant noise with guitars when using an

>> >  adapter that's then plugged into an RCA plug on the Delta 1010LT.

> Adapters don't normally introduce noise or degradation. But they

> are often used to connect things that are not compatible anyway,

> and they tend to fail (bad contacts) after some time. Try to avoid

> them, they are in general a nuisance.

>

> RCA inputs are 'consumer line level' and unbalanced, which is

> a disadvantage.

>

> Line inputs are not meant for guitars, so those people who

> are complaining get what they ask for.

>

>> >  2.  Some interfaces seem to have a combination jack that allows XLR and

>> >  1/4" inputs.  Are these good?  Or is there a tradeoff between

>> >  convenience and sound quality?

> Sound quality is not determined by the connector. But the use of

> such connectors can indicate 'budget quality'. Very often they are

> used as a combined mic/line input (mic = XLR, line = TRS). Then

> it depends: if the line input is just an attenuator feeding the

> mic input that's not really very good. A real line input does not

> pass via the mic preamp.

>

>> >  3. ... Put another way, if you have the chance to pick up at a

>> >  really good price Z-Audio's UberSuperDuperInterface, with a gazillion

>> >  ins/outs and a lot of features, and right now you only need a small

>> >  fraction of what it can do, are there non-cost reasons why you

>> >  *shouldn't*  get it?

> No.

>

>> >  a)  Guitar cables typically use a TS connector while line-level devices

>> >  (analog outs on drum machines, keyboards, etc.) typically use TRS,

>> >  right?  I'm presuming there's a difference in voltage range as well

>> >  (hence why guitars aren't referred to as line-level)?

> Guitars are not line level, they produce a much weaker signal and

> need a preamplifier with a high input impedance. Some sound cards

> have 1 or 2 inputs that can be switched for use with guitars.

> Without those you need a DI box.

>

>> >  b)  Am I correct in thinking that a cable with TS connectors is

>> >  unbalanced and a cable with TRS connectors is balanced?

> A cable with TRS connectors*can*  be balanced, one with TS

> definitely is not balanced.

>

>> >  c)  My understanding is that in order to plug a guitar into a balanced

>> >  input, there needs to be a DI box in-between to change the impedance.

>> >  But in advertising blurbs, some 1/4" inputs on interfaces are billed as

>> >  accepting balanced or unbalanced input. Does that mean that both

>> >  guitars and line-level devices can be plugged into them?

> Any balanced input will accept balanced and unbalanced signals.

>

>> >  If an interface only has mic/line jacks, does that mean you*must*

>> >  get a DI box to plug in a guitar?

> Yes, unless the line input can be switched to high impedance and has

> enough sensitivity. As already mentioned, some interfaces have such

> inputs. But you can't use a standard mic or line input for a guitar.

>

>> >  d)  Since guitars aren't at line level, do they need preamplification

>> >  like microphones do?

> Yes. Normally the DI box is connected to a microphone input.

>

>> >  Or if an interface has unbalanced inputs, can you just plug a

>> >  guitar in and go?

> In most cases not, see above.

>

> Some other things to consider:

>

> Usually you get what you pay for. Quality is not only sound

> quality, but also construction and reliability, and it has

> a price.

>

> If you are a musician, consider the combination of a simple

> but good quality soundcard having only balanced line inputs

> and outputs (even fixed level) with one the many small

> musician's mixers. These usually have mic and guitar inputs,

> a headphone output etc. Such a combination is much more

> flexible than any soundcard.

>

>

> Ciao,

>

> -- FA

Fons, interesting view. Could you give specific examples of such

soundcards and small musician mixers?
Regards,

Dirk

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