LMII DI - Jumper on Pre/Post EQ?

[Tony G]

+1... for short cable runs, that will work fine.

Define short.

 

[KJung]

Define short.

Less that 50'

Edit: Actually, I might not know what I'm talking about here. I guess it's leaving the amp as a low impedance balanced (DI) signal, so I'm not sure what impact, if any, there would be to terminating it into a high impedance input.

Regardless, you won't have any trouble either way.

 

[Big String]

I always thought short meant not longer than an 18ft. cable for balanced signal.

 

[51m0n]

I think people have the wrong impression aout balanced LINE level here.

Sorry KJung, but in this case I think you may be mixing up mic level balanced, for which 50' really is the maximum, and line level which is orders of magnitude hotter and therefore far less degraded by distance.

50ft should be no problem from the back of an LMII IMO....

 

[Tony G]

Ok, thanks for the help guys. I don't think the xlr cable I'm using is longer than 20 feet so it looks like I should be just fine.

 

[figuredbass]

Chimin' in if I may, as I've gotten very familiar with the LMII's technical specs...

If you were to use the tuner out instead of the DI out you wouldn't need to use an XLR-to-1/4" adapter at all. The actual level of the tuner out as best I could measure it is only a few dB higher than the instrument's level at the LMII input, after the Gain control has been optimally set. (This would normally vary some as the LMII's outputs are entirely dependent on the Gain control's setting.) My vote would be to use the tuner output as it's also buffered like the DI, unless you need an EQ'd signal from the DI or if you are experiencing ground loop noise because of the unbalanced 1/4" connections. The tuner out will not have to be padded down as much at the Alesis too. But if it turns out you do need to use an XLR to 1/4" adapter, make sure it is NOT one of those crappy transformer type adapters usually used for vocal mics as you will degrade the sound quality - particularly in the low end! It should be a straight-wire adaper instead.

Both the DI and tuner out have approximately 1K output impedance, which as Ken and 51m0n said will be OK for runs up to 50ft. (100ft. absolute max before you start audibly losing high end.)

Unfortunately there is still a slight possibility that either of these LMII outputs may not be compatable with the Alesis' input, so if your sound thins out or has other problems you may just have to use a quality DI box instead of the LMII as a DI.

 

[KJung]

I think people have the wrong impression aout balanced LINE level here.

Sorry KJung, but in this case I think you may be mixing up mic level balanced, for which 50' really is the maximum, and line level which is orders of magnitude hotter and therefore far less degraded by distance.

50ft should be no problem from the back of an LMII IMO....

+1.. that's why I put the edit in that I think I'm over my head here and probably not right. I was thinking about mic level balanced. Thanks for the straight scoop.

K

 

[deBont Amps]

... or if you are experiencing ground loop noise because of the unbalanced 1/4" connections.

Ground loop issues and noise in your signal don't nessacerily have to do with one another. Ground loop (different potentials and/or phase at the amp and mixer) can cause hum, but other noises can be produced by e.g. lighting, transmitters, mobile phones, etc.

... The tuner out will not have to be padded down as much at the Alesis too.

The Alesis has got balanced line inputs. These can take 20dB(!) more than the mic inputs. So no problem there.

... Unfortunately there is still a slight possibility that either of these LMII outputs may not be compatable with the Alesis' input, so if your sound thins out or has other problems you may just have to use a quality DI box instead of the LMII as a DI.

Again, the Alesis comes with balanced 1/4" jackplug line-level inputs. Use a balanced cable from XLR to 'stereo' jack (with 2 black rings). This should take care of any clipping, while getting the signal balanced and therefor hum-free to the mixer.

 

[Tony G]

Chimin' in if I may, as I've gotten very familiar with the LMII's technical specs...

If you were to use the tuner out instead of the DI out you wouldn't need to use an XLR-to-1/4" adapter at all. The actual level of the tuner out as best I could measure it is only a few dB higher than the instrument's level at the LMII input, after the Gain control has been optimally set. (This would normally vary some as the LMII's outputs are entirely dependent on the Gain control's setting.) My vote would be to use the tuner output as it's also buffered like the DI, unless you need an EQ'd signal from the DI or if you are experiencing ground loop noise because of the unbalanced 1/4" connections. The tuner out will not have to be padded down as much at the Alesis too. But if it turns out you do need to use an XLR to 1/4" adapter, make sure it is NOT one of those crappy transformer type adapters usually used for vocal mics as you will degrade the sound quality - particularly in the low end! It should be a straight-wire adaper instead.

Both the DI and tuner out have approximately 1K output impedance, which as Ken and 51m0n said will be OK for runs up to 50ft. (100ft. absolute max before you start audibly losing high end.)

Unfortunately there is still a slight possibility that either of these LMII outputs may not be compatable with the Alesis' input, so if your sound thins out or has other problems you may just have to use a quality DI box instead of the LMII as a DI.

So, if I understand what you are saying here, I can run from the "tuner out" to the 1/4" line in on the mixer with an instrument cable and it should work just fine?

 

[Tony G]

Ground loop issues and noise in your signal don't nessacerily have to do with one another. Ground loop (different potentials and/or phase at the amp and mixer) can cause hum, but other noises can be produced by e.g. lighting, transmitters, mobile phones, etc.


The Alesis has got balanced line inputs. These can take 20dB(!) more than the mic inputs. So no problem there.


Again, the Alesis comes with balanced 1/4" jackplug line-level inputs. Use a balanced cable from XLR to 'stereo' jack (with 2 black rings). This should take care of any clipping, while getting the signal balanced and therefor hum-free to the mixer.

I don't understand. Are you agreeing with him?

 

[figuredbass]

Ground loop issues and noise in your signal don't nessacerily have to do with one another. Ground loop (different potentials and/or phase at the amp and mixer) can cause hum, but other noises can be produced by e.g. lighting, transmitters, mobile phones, etc.

I'm speaking of ground loop hum here, which IS a type of noise. I think it's perfectly clear that when I say "ground loop noise" I mean "hum." Any extraneous sound other than from the signal can be considered noise. It certainly is to me.

Quote:
Originally Posted by figuredbass http://www.talkbass.com/forum/showthread.php?p=5626602#post5626602
... Unfortunately there is still a slight possibility that either of these LMII outputs may not be compatible with the Alesis' input, so if your sound thins out or has other problems you may just have to use a quality DI box instead of the LMII as a DI.

Again, the Alesis comes with balanced 1/4" jackplug line-level inputs. Use a balanced cable from XLR to 'stereo' jack (with 2 black rings). This should take care of any clipping, while getting the signal balanced and therefor hum-free to the mixer.

The compatibility issue I'm referring to is not a generic one regarding balanced connections, but specific to the Little Mark II's DI, as problems have reported by many LMII users. This issue sometimes causes problems with low frequency response with certain mixer/board inputs. There have been a lot of posts here reporting it. The problem appears to be within the design of the LMII's DI itself, not the type of connection being made.

 

[figuredbass]

So, if I understand what you are saying here, I can run from the "tuner out" to the 1/4" line in on the mixer with an instrument cable and it should work just fine?

I believe it will, although you still could run into that LMII impedance problem [as reported with its DI] since that output is configured similarly to the DI. If it isn't a hot enough signal, then yet another option would be to take the output from the LMII's effects send, which is a true line level output (+4 dBu). This output will NOT cause the "impedance match" problem that some LMII users have reported with the DI. It's an "unbalanced" output that can be plugged directly into the Alesis' 1/4" line input. Remember that the effects send output is always pre-EQ, no matter how you set the DI's internal jumper.