VG-99 - XLR Sub Out into input of guitar amp

[ericar123]

Hi
Can I get an XLR to 1/4 adapter and take one side of the sub out and go to the input of my guitar amp?
I want to leave my left and right outputs going to my computer. I would like to use my virtual guitars
and wah pedals through my amp . The reason I ask is that I have not used XLR outputs before and wonder
if it will be ok for my tube amp head. I found this adapter.

http://www.long-mcquade.com/1616/Pro_Audio_Recording/Cables/Yorkville_Sound/Link_Audio_1_4_Male_to_XLR-F_-_20_foot.htm

Thanks for any help

[Elantric]

No

IMHO - its best to feed the VG-99 Sub XLR outs into your separate Audio Recording Interface - because the VG-99's Sub XLR Outs are +4 dBu level and always fixed at Line / Phones with Speaker Cab Modeling always engaged.

The VG-99 Main 1/4" output are more flexible and using "Output Select" can disable the VG-99 Speaker Cab Modeling  - so your external Amp can work best.

[ericar123]

Thanks for the reply.
I really don't understand the 3 pin XLR plug. I guess I was just worried about the output and if it would hurt
either my soundcard input or my tube amp. The adapter gets rid of one of the pins but I don't understand the difference it has with the 1/4 inch outputs.

[Elantric]

What is your soundcard make / Model?


I use XLR F to 1/4" TRS cables  and feed  the VG-99 Sub XLR Stereo Outs to a pair of  Balanced 1/4" TRS Line Inputs on my Audio Interfaces ( MOTU 828Mk2, Focusrite Scarlett 18i20, etc) 

http://www.sweetwater.com/store/detail/BPBQXF10/

[ericar123]

I use an M-Audio 24/96 audiophile.

http://www.m-audio.ca/products/en_us/Audiophile2496.html

[Elantric]

I use an M-Audio 24/96 audiophile.

Well - you only have RCA unbalanced Audio I/O, which will be prone to noise. (yikes)

You will obtain lower noise recordings using the VG-99 as your USB audio interface in your home studio 

[Kevin M]

I think that card has SPDIF I/O as well.


Sent from my iPad using Tapatalk

[ericar123]

I have tried USB many times and it never works good. I have never tried SPDIF. Do I just use a regular RCA audio cord?

[ericar123]

Another weird problem I have is that I get a bad hum like a ground loop if I leave my USB plugged into the computer as well as my audio cables or midi cables.

[Elantric]

Another weird problem I have is that I get a bad hum like a ground loop if I leave my USB plugged into the computer as well as my audio cables or midi cables.

USB Noise - audio output  has enormous noise with USB cable connected
https://www.vguitarforums.com/smf/index.php?topic=367.0


Amazon sells RCA SPDIF cables, although I've had success using Yellow RCA Composite Video (75ohm)  type cables. The VG-99 has SPDIF out, so that path is worth a try.


Cable, S/PDIF Coax RCA, 2 Meter
http://www.fullcompass.com/product/390641.html

Another weird problem I have is that I get a bad hum like a ground loop if I leave my USB plugged into the computer

Actually thats indicative of a Ground Loop, and using an Ebtech AC Ground Hum Eliminator on the Power supply of either Computer or VG-99 can help tame that noise


read
Diagnosing and Fixing Ground Loops to Prevent AC Hum/Buzz
http://www.ebtechaudio.com/findloop.pdf

and

Ground Loops Tutorial
https://www.vguitarforums.com/smf/index.php?topic=6525.msg45012#msg45012

[Martin Turner]

Thanks for the reply.
I really don't understand the 3 pin XLR plug. I guess I was just worried about the output and if it would hurt
either my soundcard input or my tube amp. The adapter gets rid of one of the pins but I don't understand the difference it has with the 1/4 inch outputs.

I guess this is an old thread, but the additional question wasn't really answered.

XLR connectors, also called sometimes 'Audioconn plugs' or 'locking Cannon connectors' are for balanced cables.

Essentially, a regular signal has a Signal +ve and an Earth (also called Ground). This is the minimum necessary for a circuit.

A balanced cable has Signal +ve, Signal -ve, and an Earth.

The +ve and -ve signals are generated by the device: with a microphone or DI box it's about how you tap the transformer.

At the other end, an operational amplifier subtracts the negative from the positive, resulting in a double strength signal.

On a long cable run, the cable picks up noise, which will be the same on both the +ve and -ve lines. So, when the operational amplifier subtracts the -ve from the +ve, the noise is subtracted. The result is you have a double strength signal, with virtually no noise.

If you use an adaptor which discards the -ve signal, you have lost the main benefits of a balanced signal.

Balanced signals are almost always (and should always be) low impedance. This also substantially reduces noise on a long cable run.

Balanced signals come in three flavours: mic-level is typically around 25 mV, but could be anything from 5-50 mV. Line level is either consumer or pro. Pro signals are +4dbU, which is essentially double the voltage of consumer versions. Line signals are 0.3 - 2 V, with the consumer at the lower end, and the Pro at the higher end.

Although the Sub Out on the VG-99 is natively Pro Level at +4dbU, you can set the signal to much lower, even down to mic level, using the Sub level control which is the final page on the Global Settings.

As well as XLR connectors, you can also use TRS jacks (tip-ring-shield, as opposed to normal TR jacks). For some reason, this is standard on some equipment. The advantages of XLR connectors are i) they are noiseless when inserted or removed, even on a live system, ii) they are noiseless when left lying around, and iii) they can carry Phantom power, useful for powering condenser microphones and DI boxes.

Early models of XLR connectors required a screwdriver to inspect, but Neutrik (and imitation Neutrik) connectors just screw open like jack plugs. All XLR connectors contain strain relief, whereas this is only found on high-end jacks.

By contrast, a guitar cable will usually be 50k Ohms impedance, which is one reason why guitars are so susceptible to noise, and, on cheaper cables, lose tone on long cable runs because of capacitance effects.

Hopefully this helps someone.