Do I need a DI box, preamp or something else?

[flimdoo]

Hi all, newbie here with a question about my home guitar setup. I play mainly through a Line6 Pod XT Live, which emulates lots of amps and effects digitally. It can output in both "line" and "amp" mode. If I play live I run it straight into the PA, at line level. At home, I just run it (at line level again) into a pair of powered speakers. I believe that "Amp" mode gives an instrument-level output, suitable for sending into an amp.

Now, I've bought a phrase looper pedal (a Nux Loop Core), which I want to use for practising at home. I'd like to place it after the Pod XT Live, so that it is capturing the fully-processed signal. If I send a line-level signal into it, it clips like mad, so I turn the Pod to "amp" output mode to prevent this. The pedal seems to expect an instrument-level signal, which makes sense.

If I run the output from the looper straight into my speakers, the output is very quiet, presumably because its output is also at instrument level. I assume that I should bring the output signal back up to line level - what's the best way of doing this?

I guess I could use a DI box, but is this overkill? I don't necessarily need a balanced output, because the cable runs are very short. (My speakers take input through phono connections by the way, not XLR.) So is this a job for a preamp, or headphone amp, or something like that, instead? And if a DI box is the way to go, should it be active or passive? I'm not looking for an expensive (or necessarily high-quality) solution because it's only for home practice. But I don't want something that is going to colour the signal too much if I can avoid it.

Thanks in advance for any help!

 

[Steenamaroo]

Hi there, and welcome to the forums!

What sort of cables are you using between Line6 and amp, or line6 and looper pedal?

I'm glancing at the manual and it says "Be sure to use TRS cables when you want to get +4dBu levels tothe balanced inputs of a recorder,mixer or power amp. "
I presume, then, you'd want to use TS (instrument) cables if you're going into another pedal/looper.

 

[ecc83]

I would like the make and model of the active speakers? The fact is, a lot of such speakers have TOO MUCH gain and are therefore noisy. It is unusual not to have enough and especially into an RCA socket you would expect -10dBV operation.

Feed the speakers from the Line 6 pod in 'amp' mode. If that gives adequate volume suspect cables or a faulty looper.

Dave.

 

[keith.rogers]

The speakers expect a line level, which "amp mode" will not supply, since it's an instrument level, i.e., too low of voltage.

If you have an interface you could take the amp mode into your AI (instrument level input/switch) and use its monitor out to drive the speakers if it has a direct monitoring mode, i.e., does not expect/need to make the AI(A/D)->computer->AI(D/A) round trip.

Failing that, you can get an older, used Behringer 2-channel analog mixer around these parts for probably $25 or less that would solve your problem.

 

[ecc83]

The speakers expect a line level, which "amp mode" will not supply, since it's an instrument level, i.e., too low of voltage.

If you have an interface you could take the amp mode into your AI (instrument level input/switch) and use its monitor out to drive the speakers if it has a direct monitoring mode, i.e., does not expect/need to make the AI(A/D)->computer->AI(D/A) round trip.

Failing that, you can get an older, used Behringer 2-channel analog mixer around these parts for probably $25 or less that would solve your problem.

Did you clock the speaker make then Keith? I didn't. The OP might get away with a headphone amp. S/H mixer is a good call.

Dave.

 

[keith.rogers]

Did you clock the speaker make then Keith? I didn't. The OP might get away with a headphone amp. S/H mixer is a good call.

Well, no, I just assume any powered speaker is looking for at least consumer level line input, i.e., they don't have anything except a power amp section, really.

I actually had to go and look, and the low-end Behringers probably needs a DI as well so you can send the guitar signal into the XLR (mic) input, since they don't have an instrument input. So, maybe not the cheapest solution if you don't already have a DI (though everyone should have a DI laying around somewhere!).

 

[ecc83]

Well, no, I just assume any powered speaker is looking for at least consumer level line input, i.e., they don't have anything except a power amp section, really.

I actually had to go and look, and the low-end Behringers probably needs a DI as well so you can send the guitar signal into the XLR (mic) input, since they don't have an instrument input. So, maybe not the cheapest solution if you don't already have a DI (though everyone should have a DI laying around somewhere!).

w
Well BUGGER ME! It has taken me ages to find a sensible specification for active monitor input sensitivity! I eventually found that the Genelec 8010a needs -10dBV for 100dBSPL (it also has a -6dBu switch) .
I cannot say for sure but I suspect most active speakers will deliver full output for around 300mV?

It is always tricky when you delve into the murky world of Operating Levels. +4dBu is well known of course but 'Consumer' level? If you mean hi fi, cassettes and such that was nearer 150mV, -16dBV. But 'The World' really never got THAT together!

Dave.

 

[flimdoo]

Thanks everyone very much for your replies! In answer to your various questions:

- I'm just using instrument cables to go guitar -> PodXT Live -> Looper pedal. The active speakers take stereo phono plug inputs so I have a 1/4" jack to stereo phono cable to go from the looper pedal to the speakers. I don't have any balanced inputs anywhere in the system. All cable runs are short.

- The speakers are actually computer speakers - Bose Companion 2. I don't think they sell this particular model anymore and I don't have the specs. They are about 12 years old. They aren't proper powered monitor speakers but do just fine for low-volume guitar practice!

- There is no audio interface involved. Apart from the digital processing going on in the Pod, all the connections are analogue.

- To clarify, I'm not getting noise issues - it's just that the sound output is quiet because I'm sending instrument level from the looper into the speakers, which expect line level. I'm just looking for a convenient (and inexpensive) way to boost the signal between the looper and the powered speakers, and wasn't sure if I'd need a full DI box, or just some kind of preamp or headphone amp, preferably one with simple unbalanced jack or phono inputs and outputs (since the speakers take unbalanced inputs).

Would a headphone amp or powered mixer bring the signal up to line level?

 

[keith.rogers]

....Would a headphone amp or powered mixer bring the signal up to line level?

Well, there are different kinds of headphone amps.

Many are designed to take a line level and add a volume controlled amplifier stage (low powered, admittedly) for multiple outputs, e.g., to allow more than one person to listen with headphones in a recording session. That type is likely not going to provide the gain you'll need, though some might. You'd have to test around or find someone that's actually used the equipment for the same purpose you are planning.

What you might look for is one of those gizmos that you can plug your guitar into directly that produces a headphone level output. Then take that headphone output's stereo plug (1/8" or 1/4") and split that to an RCA pair. Workable, but a little clunky IMO.

A DI alone will not provide any gain in the signal. I'd still consider getting a passive DI ($20 - which is how I'd go to the PA system from your POD too!) and a used analog mixer (probably well south of $40 - I see ones in GC's used listings for $20), because it's more like what you'll be doing when you play out, if for no other reason.

 

[flimdoo]

Thanks keith.rogers, much appreciated. Is there anything I should look for in the specs of a headphone amp, e.g. a certain level of gain? If a headphone amp isn't quite the right thing, what about a phono preamp (designed to go between a turntable and an amp)? There are quite a few out there for £20 or so.

What you might look for is one of those gizmos that you can plug your guitar into directly that produces a headphone level output. Then take that headphone output's stereo plug (1/8" or 1/4") and split that to an RCA pair. Workable, but a little clunky IMO.

I assume you mean things like the Vox Amplug and its kind? I did wonder about that, but I was thinking that it would colour the signal - I'd want to make sure it's very clean, at least. Given that the PodXT is already acting as my amp (it has amp and cabinet simulators) I wasn't sure about adding another guitar amp in the chain. Could be worth a try though!

A DI alone will not provide any gain in the signal.

Ah, that was my misunderstanding - thanks for clearing that up.

I'd still consider getting a passive DI ... which is how I'd go to the PA system from your POD too!

OK, thanks. Out of interest, why do you say that I should use a DI box between the POD and the PA? Is it to get a balanced output and reduce line noise or are there other reasons too? I think the later-generation PODs have balanced outputs built in, but mine is only unbalanced. My cable runs tend to be short and I haven't noticed an issue yet.

Your mention of a mixer reminds me that I have an old 4-track recorder that takes unbalanced inputs and has trim controls to boost input levels. I guess I could use that and use the monitor outputs to my speakers? Only issue is that it takes up a fair amount of space and seems like overkill for such a simple task!

 

[ecc83]

Isn't it odd that no one seems to make a 2 channel clean booster box?

2 x RCA in and 2X TRS out, impedance balanced would do for projjy studio work. Switched for unity gain or -10dBV up to +4dBu.

Dave.

 

[keith.rogers]

...Is there anything I should look for in the specs of a headphone amp, e.g. a certain level of gain? If a headphone amp isn't quite the right thing, what about a phono preamp (designed to go between a turntable and an amp)? There are quite a few out there for £20 or so.

A phono preamp will have RIAA equalization built in and, unless you can bypass that, be fairly useless for what you want. I have done a bit of googling and find that hard specs on headphone amps are pretty hard to come by. You're basically stuck with something designed for a line-level input, which might have enough gain, or a guitar-specific thing, with it's own issues. The Behringer MA400 actually looks kind of interesting, but you'd need a DI for that, too, since it expects a low-impedance (I ASSUME because I can't find full specs!) for the MIC input or line level for the MONITOR input.

I assume you mean things like the Vox Amplug and its kind? I did wonder about that, but I was thinking that it would colour the signal - I'd want to make sure it's very clean, at least. Given that the PodXT is already acting as my amp (it has amp and cabinet simulators) I wasn't sure about adding another guitar amp in the chain. Could be worth a try though!

Yes, I'd expect something like a Vox Amplug would definitely color the signal.

OK, thanks. Out of interest, why do you say that I should use a DI box between the POD and the PA? Is it to get a balanced output and reduce line noise or are there other reasons too? I think the later-generation PODs have balanced outputs built in, but mine is only unbalanced. My cable runs tend to be short and I haven't noticed an issue yet.

Well, I was thinking about if you intended to use the looper pedal output. Generally that kind of level should switch to a balanced, low impedance line since it would be more susceptible to external noise than a line level run. And, if you ever need an "amp" to play out you could just grab any spare powered PA speaker/monitor to stick the mixer outputs into, and you'd know how it would sound.

Your mention of a mixer reminds me that I have an old 4-track recorder that takes unbalanced inputs and has trim controls to boost input levels. I guess I could use that and use the monitor outputs to my speakers? Only issue is that it takes up a fair amount of space and seems like overkill for such a simple task!

Can't hurt to try, but when I was using a POD HD 400 pretty regularly for a few years, I tried to make sure that the only thing that changed from my home monitoring to the gig was the board that I was plugging into. So, using something very different to monitor, like a headphone amp, could create a false sense of what it was going to sound like when I got live. And heaven knows fiddling with those things in a gig situation if you have a lot of patches is not the point, at least IMO.

 

[flimdoo]

Thanks Dave and Keith. Must admit that when I asked the question I didn't expect things to be this complicated! ;-)

Dave - yes, I was expecting someone just to point me to something like a 2-channel clean boost but I can't find one either!

Keith - I don't really use the looper in the studio or live, so I'm happy sending a line signal from the POD to the PA. I only use it for practice at home. By the way, I got hold of an Amplug and tried it out on its cleanest setting - sounded pretty awful, the output is very noisy in this situation!

Anyway, this discussion has given me a much better understanding of what's going on, so I'm very grateful for all your replies!

 

[redhatbeats]

Check out the ART Tube MP or Behringer MIC 200

 

[drtechno]

Hi all, newbie here with a question about my home guitar setup. I play mainly through a Line6 Pod XT Live, which emulates lots of amps and effects digitally. It can output in both "line" and "amp" mode. If I play live I run it straight into the PA, at line level. At home, I just run it (at line level again) into a pair of powered speakers. I believe that "Amp" mode gives an instrument-level output, suitable for sending into an amp.

Now, I've bought a phrase looper pedal (a Nux Loop Core), which I want to use for practising at home. I'd like to place it after the Pod XT Live, so that it is capturing the fully-processed signal. If I send a line-level signal into it, it clips like mad, so I turn the Pod to "amp" output mode to prevent this. The pedal seems to expect an instrument-level signal, which makes sense.

If I run the output from the looper straight into my speakers, the output is very quiet, presumably because its output is also at instrument level. I assume that I should bring the output signal back up to line level - what's the best way of doing this?

I guess I could use a DI box, but is this overkill? I don't necessarily need a balanced output, because the cable runs are very short. (My speakers take input through phono connections by the way, not XLR.) So is this a job for a preamp, or headphone amp, or something like that, instead? And if a DI box is the way to go, should it be active or passive? I'm not looking for an expensive (or necessarily high-quality) solution because it's only for home practice. But I don't want something that is going to colour the signal too much if I can avoid it.

Thanks in advance for any help!

simple gain is what you need, so yes you could use a simple headphone amp