Recoding a bass guitar

[danieldldsParticipant]

Hello,

I am using a Qu16 as an audio interface to my computer. When recording a bass guitar directly by plugging it to the TRS jack on channel 1, the sound volume a bit low. How can I make the recording louder ? Do I some sort of pre-amplification ? Doesn’t the QU16 already has that ?

Thanks

[GCumbeeParticipant]

Use a direct box. Active or passive. Plug the bass into it and the xlr into a mic input connector. Adjust to suit. Probably have better results.

[DoctorGParticipant]

Yes, a direct-input (DI) box or other device is required for connecting a guitar to a mixer that does not provide a high-impedance input designed for this purpose.

Most guitars use a pickup that can generate very little current, meaning that it must operate into a circuit that has a high resistance (impedance). If connected to a low impedance input, the pickup is not able to produce it’s full voltage, hence a low signal level results. In addition, the guitar connector is unbalanced (TS), and connecting it to a balanced input (TRS) cuts the signal level in half, compared to the normal TRS signals. The DI box converts the unbalanced input into a balanced output.

Some mixers and other preamps have special inputs, usually switchable, to accommodate guitars, but the QU series does not.

[danieldldsParticipant]

Thanks for the replies. How about micing the amp ? The results being diferent, will it provide a higher signal level, while not setting the amp volume to the max ? I have the famous Sures SM57.

Regards

[MarkPAmanParticipant]

If the amp sounds good, then no reason not to stick a mic in front of it & record that.

[DaveParticipant]

A 57 is probably not best suited for bass. But it will work, and if you like what you hear, then there is no reason not to use it.

[cornelius78Participant]

I’ll just add that IIRC the line inputs on the Qu Series have a 10db pad c/f the XLR inputs, which will further diminish the level you get.

Re micing the amp: it’ll certainly sound different, as if you go bass>di>mixer then you’re getting the signal straight off the bass guitar. If you have a head with an output at an appropriate level and record off that, the head will colour the sound a bit. If you mic the cab, then you’ve got the sound of the cab + room, along with the mic’s own characteristics, in addition to the bass head, to colour the sound.

It’s not unheard of to use multiple channels for a single instrument, even live. eg use a DI for the bottom end in one channel and mic the cab (even with a non-bass mic, like your ’57) for the top, then mix both channels together.

[Dick ReesParticipant]

Two things:

1. Impedance of the DI should be matched to the loading requirements of the pick-up as Doc G stated. Passive pick-ups require a high input impedance, usually a minimum of
1Mohm…or more. Active pick-ups may or may not.

I carry BSS 133’s in my kit. They have three selectable impedance levels, the highest being 1Mohm. These have never failed to do the ir assignment properly.

2. When using both DI on the bass prior to the amp AND miking the cabinet it is necessary to consider the latency involved. You may well need (or prefer) to use input delay on the DI channel to address any phase issues due to latency. It’s not strictly necessary, but you should be aware of the situation and be prepared to deal with it as needed.

[DoctorGParticipant]

I started to mention miking the guitar amp (the speaker cab) in my previous response but decided that you had your reasons for the direct connection.

As was stated previously, the direct sound from the guitar will be different from that of the amp, for several reasons, including the response curve of the speaker, the response curve of the mike, and any processing applied by the amp, but you will be miking the sound that you are sending to the audience. I have read that some engineers try to use both the direct and amplified signals and blend them appropriately. As was stated, latency could be an issue, but it may also add a type of “reverb” that may be desirable, and this can be controlled by a digital mixer. Lots of things to consider here.

The Shure SM57 is a standard for miking amps, but I tend to prefer condenser mikes for miking a bass amp, due to their lower and flatter low frequency response. Apply a low-pass filter to remove most of the mids and high frequencies. This will also help minimize feedback in a live situation.

I generally use a Shure PG81 for this purpose, but inexpensive mikes such as the AKG Perception 170, the CAD 195, Shure PGA81-LC or SM137LC will also work fine in this application. I see no need for an expensive mike for this purpose. If you are operating in a live, very high level situation, pay attention to the maximum SPL the mike can withstand. You have said that you are not in a live situation, so what I have said about that will not be pertinent – just trying to cover the basics.

Because of all the variables involved in miking the amp, using the direct approach may be preferable, if you can get the sound that you want from the guitar with effects available on the mixer or your DAW. Effects probably are not so important for a bass guitar, however. Personal preferences will dictate your choice.

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