Help needed rising to the gain challenge:

[Charlie Bernstein]

Playing electric guitar, I understand how to use all the knobs on the guitar, the pedals, and the amp.

But I'm new to acoustic miking, and it still has me scratching my dome.

I have a mic tube preamp with two knobs: input and output. It's plugged into a powered speaker with one knob.

That's three knobs. What's the difference between turning up one or another? How do I know which to turn up and which to turn down?

Again, the three are preamp in, preamp out, and speaker.

Thoughts? Advice? Condolences?

Thanks!

 

[El Tele Lobo]

Someone correct me if I’m wrong, but I believe the input knob will primarily affect gain (and to a lesser degree, possibly compression) while the output knob and the knob on the speaker will specifically control volume level.

A number of factors, including the strings you use, the style of music you play and you’re playing technique will have to be accounted for in terms of how you adjust all three knobs. I wish there was an easy answer, but you’re probably just going to have to experiment.

I have found with my Henriksen Bud amplifier, that input gain can help add a little bit of compression even to a clean signal… But beyond a certain point tends to cause certain frequencies to come across as harsh. I found the same thing to be true of having the guitar volume on 10, even at a lower volume on the amp. So I tend to run my guitar volume at about 7 to 9, watch my level on input gain, and adjust the master volume on the amp to level that I want for playing.

Even with tube amplifiers, when running clean, I find I get a better clean tone with the guitar volume backed off a bit, and the amp turned up. There was definitely a sweet spot with my champ clone. Obviously, when you’re going into overdrive, some of this goes out the window… Though I still prefer to have the amp turned up and achieve a clean tone versus an overdriven tone using the volume knob on the guitar primarily.

 

[Charlie Bernstein]

. . . I found the same thing to be true of having the guitar volume on 10, even at a lower volume on the amp. So I tend to run my guitar volume at about 7 to 9, watch my level on input gain, and adjust the master volume on the amp to level that I want for playing.

Even with tube amplifiers, when running clean, I find I get a better clean tone with the guitar volume backed off a bit, and the amp turned up. . . .

Helpful. Thanks!

Just to be clear (since I wasn't), none of my folk guitars and resos have volume knobs. I'm miking them. And, of course, my voice doesn't, either. That's why I'm just asking about those three knobs I mentioned: two on the preamp, one on the speaker.

So I'll take this to mean that where you talk about guitar volume, I can take that to mean the input knob on the preamp, and when you talk about master volume, that's the speaker knob.

In short:

- Keep the input knob lower for cleaner or open it for more saturation.

- Open up the output knob for a stronger signal.

- Use the speaker knob to fit the size and noisiness of the room.

Is that about right?

 

[Charlie Bernstein]

Someone correct me if I’m wrong, but I believe the input knob will primarily affect gain (and to a lesser degree, possibly compression)

PS -

That makes sense. The preamp has a Mullard 12AX7 in it, so turning the input knob up a bit might make a juicier signal.

while the output knob and the knob on the speaker will specifically control volume level.

So do you think the preamp's output knob and the speaker knob do more or less the same thing? (That would be nice.)

A number of factors, including the strings you use, the style of music you play and you’re playing technique will have to be accounted for in terms of how you adjust all three knobs. I wish there was an easy answer, but you’re probably just going to have to experiment. . . .

I started yesterday with both input and output at noon. I'll start there again and fool with it from there.

. . . Even with tube amplifiers, when running clean, I find I get a better clean tone with the guitar volume backed off a bit, and the amp turned up. There was definitely a sweet spot with my champ clone. Obviously, when you’re going into overdrive, some of this goes out the window… Though I still prefer to have the amp turned up and achieve a clean tone versus an overdriven tone using the volume knob on the guitar primarily.

Same here. Thanks!

 

[Peegoo]

@Charlie Bernstein

Here's a quick primer:

The level controls on the preamp allow you to maintain unity gain through the preamp to keep the signal as strong as possible but as distortion-free as possible. It's adjustable because there are all kinds of varying voltages the unit might see in use, from a low-power passive K&K piezo pickup (bring up the input gain), to something like an 18v Fishman guitar preamp built into the guitar (back off the input gain).

If the signal into the preamp is too low, your signal-to-noise ratio will be too low and you'll have hiss and stuff in the sound. If the signal going in is too high, it will be distorted and harsh. You want the highest gain before distortion.

Does the preamp have an input meter on it? Older equipment used d'Arsenval meters with a swinging needle that displayed dB levels. Most modern stuff these days usually has a single LED that flashes green when input signal level is good, and as the signal becomes too hot, it turns yellow and then red. "Too hot" means the preamp is no longer able to output a clean signal. Some "meters" are a series of LEDs.

So how do you set levels?

Generally, you set levels in sequence through your sound reinforcement chain, starting with the source. Plug the guitar into the preamp and play as hard as you will when the show is on. Watch the meter and adjust the input gain so everything is green. It's just like when setting up a signal chain for making a recording. You want the 'needles' bouncing in the green without breaking into the red line much--if at all.

The volume on your powered speaker is the overall volume. If it has a separate gain control, set that first, with the master volume turned to zero. You want the needle bouncing in the green. Remember to play the guitar as hard as you will when the show is on.

Same goes for setting microphone levels.

 

[Charlie Bernstein]

@Charlie Bernstein

Here's a quick primer:

The level controls on the preamp allow you to maintain unity gain through the preamp to keep the signal as strong as possible but as distortion-free as possible. It's adjustable because there are all kinds of varying voltages the unit might see in use, from a low-power passive K&K piezo pickup (bring up the input gain), to something like an 18v Fishman guitar preamp built into the guitar (back off the input gain).

If the signal into the preamp is too low, your signal-to-noise ratio will be too low and you'll have hiss and stuff in the sound. If the signal going in is too high, it will be distorted and harsh. You want the highest gain before distortion.

That makes sense. It's good to see it spelled out. It sounds like the input knob is where the real action is. Dial it to where it sounds best.

Does the preamp have an input meter on it?

It looks like this:

As you can see, there's a light that turns red when it starts to clip.

I'm trying this old preamp instead of my mixing board to see how well it does. My goal is to get a good sound with as few controls as possible.

So far, all I can say for sure is that this setup sounds better than my old Loudbox Mini.

Older equipment used d'Arsenval meters with a swinging needle that displayed dB levels. Most modern stuff these days usually has a single LED that flashes green when input signal level is good, and as the signal becomes too hot, it turns yellow and then red. "Too hot" means the preamp is no longer able to output a clean signal. Some "meters" are a series of LEDs.

So how do you set levels?

Generally, you set levels in sequence through your sound reinforcement chain, starting with the source. Plug the guitar into the preamp and play as hard as you will when the show is on.

As I said, I'm miking the vocals and guitar, not plugging the guitar in. I'm using an LDC mic and powered speaker. So far, the combination seems to be working. But I haven't field-tested it yet.

Watch the meter and adjust the input gain so everything is green. It's just like when setting up a signal chain for making a recording. You want the 'needles' bouncing in the green without breaking into the red line much--if at all.

No needles on this one.

The volume on your powered speaker is the overall volume. If it has a separate gain control, set that first, with the master volume turned to zero.

It just has a single volume knob.

You want the needle bouncing in the green. Remember to play the guitar as hard as you will when the show is on.

Same goes for setting microphone levels.

Got it. This helps. What I'm wondering now is, since the input knob dictates sound quality and the speaker's knob is the master volume, what is the preamp's output knob good for? Can I just set it at noon and forget it?

 

[Peegoo]

what is the preamp's output knob good for? Can I just set it at noon and forget it?

The preamp's output knob allows fine adjustment of signal level that gets 'seen' by the next device in the chain. In your case, a powered speaker.

Some powered speakers have an input trim (gain, actually) control, so the preamp output level and speaker input level will basically do the same thing.

If there's no gain control on the speaker, set the preamp's output at 12 o'clock (probably 0dB...check the user manual for details). That will deliver the best clean signal to the speaker's amplifier stage.

 

[loudboy]

Got it. This helps. What I'm wondering now is, since the input knob dictates sound quality and the speaker's knob is the master volume, what is the preamp's output knob good for? Can I just set it at noon and forget it?

Preamps such as this are generally used for recording, so the second knob controls the level to something else down the line, like a compressor or EQ, or both. Or sets the level to "tape."

 

[Charlie Bernstein]

The preamp's output knob allows fine adjustment of signal level that gets 'seen' by the next device in the chain. In your case, a powered speaker.

Some powered speakers have an input trim (gain, actually) control, so the preamp output level and speaker input level will basically do the same thing.

Just as I suspected. Glad to know it's not more complicated than that.

If there's no gain control on the speaker, set the preamp's output at 12 o'clock (probably 0dB...check the user manual for details). That will deliver the best clean signal to the speaker's amplifier stage.

Whew! Too easy! I usually start knobs at noon, anyway, and work from there. So it won't be much work at all.

Thanks again.

Preamps such as this are generally used for recording, so the second knob controls the level to something else down the line, like a compressor or EQ, or both. Or sets the level to "tape."

Makes sense. I bought the thing fifteen or twenty years ago, just because it was ten bucks. I added the Mullard tube (another ten bucks?) three or four years ago.

Never used the preamp or had a plan for it. Then it occurred to me a few days ago that, since all the signal to a powered speaker actually needs is a boost — not reverb, EQ, or anything — it might be good for moving a clean, unadulterated signal from mic to speaker.

I love fooling with effects playing electric, but I want high fidelity for acoustic.

Thanks!