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Good vocal amp needed for small band rehearsals

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Re: Good vocal amp needed for small band rehearsals

Postby Wonks » Sun Jul 14, 2019 8:39 pm

This often happens with underpowered amps. All you can really do is move the amp away from the mic. and point the rear of the mic (it's an SM58 so cardioid) at the speaker for maximum feedback rejection. But pushing the amp so loud that it's distorting will also help bring on feedback a lot earlier than you expect.

I have to ask: Are you certain it's a genuine SM58 i.e. did you buy it direct from a music shop? There are a lot of fake SM58s and SM57s out there on eBay, and they certainly don't sound like or reject feedback as well as the real thing. Unless you know what to look for, the fakes can be very hard to tell visually from the real thing.
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Re: Good vocal amp needed for small band rehearsals

Postby CS70 » Sun Jul 14, 2019 9:00 pm

benaround wrote:Sam
I've noticed that, feedback occurs before I can get the amp up to max output.
I can't set either the gain or the master above half value.

As I wrote, in a small untreated room, feedback will get you way before you can get loud enough to even begin to compete with tube amps.

You can try and move the mic (just in case: it needs to point decidedly the opposite direction to the speaker(s) ) but what gets you usually are the reflections. Without proper absorbent walls, there's just too much that's thrown back into the mic when you up the gain.

I totally agree with the others that the others players _have_ to turn down. That's the only meaningful solution.

That said, if you want to be able to increase the vocal volume before feedback, you need an absorber behind you. The good old duvet on a T-shaped mic stand which serves so well for recording can help also in this situation - right behind you but a few feet from the wall at your back. It doesn't look pro tough. :)
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Re: Good vocal amp needed for small band rehearsals

Postby Music Wolf » Sun Jul 14, 2019 9:02 pm

benaround wrote:I've noticed that, feedback occurs before I can get the amp up to max output.
I can't set either the gain or the master above half value.

From your description of the room setup / other musicians I was expecting this to be the next problem. In addition to what Wonks has already said the simple fact is that you are too loud for the size of room. Everybody, starting with the drummer, needs to turn down.

I was working, or rather trying to work, with a couple of guys the other year who would crank things up at practice to the point that we were on the edge of feedback and the bass player was wearing earplugs. Considering that the drums were on a backing track there was absolutely no need. Some people think that you need to be loud to sound good. You don't. Playing loud just de-sensitises the ear so that you can't tell that you are shit.

Play at a comfortable level so that you can hear your mistakes - then correct them.
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Re: Good vocal amp needed for small band rehearsals

Postby CS70 » Sun Jul 14, 2019 9:04 pm

Music Wolf wrote:Play at a comfortable level so that you can hear your mistakes - then correct them.

Now' that's a good line for a signature!
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Re: Good vocal amp needed for small band rehearsals

Postby Sam Spoons » Sun Jul 14, 2019 9:38 pm

Music Wolf wrote:Playing loud just de-sensitises the ear so that you can't tell that you are shit.

Thats a better one :clap: :clap: :clap:
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Re: Good vocal amp needed for small band rehearsals

Postby benaround » Mon Jul 15, 2019 11:45 am

Wonk: Certain it's genuine, purchased in yr 2000 or so from local music shop.
CS70 thanks for duvet tip!
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Re: Good vocal amp needed for small band rehearsals

Postby Sam Spoons » Mon Jul 15, 2019 12:01 pm

Just a thought, if you've already hit the 'gain before feedback' wall you may not get any useful extra volume out of a more powerful speaker?
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Re: Good vocal amp needed for small band rehearsals

Postby benaround » Mon Jul 15, 2019 1:29 pm

Maybe, fortunately I have this G4M on loan to try out first so no money lost,
But I always thought that the more powerful the speaker, the less likelihood feedback per unit of output, or that feedback was more likely at higher gain settings within an amp, to put it another way, so that a more powerful amp would put out more volume at the equivalent gain setting to a less powerful one.
I mean, take two powered speakers, a low powered and a high powered, at a low gain setting each would be less likely to feedback, but the high power one would sound louder.
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Re: Good vocal amp needed for small band rehearsals

Postby Wonks » Mon Jul 15, 2019 1:47 pm

When I had my Yamaha DRX10 system, I set that up in my living room several times and I could get it very loud indeed before feedback. It also went a lot, lot louder with feedback - and that killed all my high frequency hearing.
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Re: Good vocal amp needed for small band rehearsals

Postby CS70 » Mon Jul 15, 2019 4:35 pm

benaround wrote:Maybe, fortunately I have this G4M on loan to try out first so no money lost,
But I always thought that the more powerful the speaker, the less likelihood feedback per unit of output, or that feedback was more likely at higher gain settings within an amp, to put it another way, so that a more powerful amp would put out more volume at the equivalent gain setting to a less powerful one.
I mean, take two powered speakers, a low powered and a high powered, at a low gain setting each would be less likely to feedback, but the high power one would sound louder.

Feedback depends on the amount and direction of energy that reaches the volume of air around the microphone, which in turn depends both on the geometry of the room and how much the walls reflect energy, and the energy level that reaches the particular areas which reflect into the mic (plus of course of the oscillation characteristics of the circuit). So long there's enough energy, how it's generated is fairly irrelevant.

There may be slight differences due to that lower powered speakers pushed more may have smaller cones or otherwise distort a little more, generating some additional energy at high frequency and therefore triggering oscillation; whereas a bigger speaker would behave more linearly and reproduce the signal with more fidelity. But I'd guess that for that to matter you really have to be at the edge of feedback anyway.
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Re: Good vocal amp needed for small band rehearsals

Postby Sam Spoons » Mon Jul 15, 2019 5:58 pm

Yup, agreed, distortion will increase the likelihood of feedback but mostly it's down to the amount of energy getting back into the mic (distortion may well increase that energy at frequencies most likely to cause feedback without increasing the usable volume of the 'wanted signal') and the threshold will depend on the room, the eq balance and the position of the mic and speaker.
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Re: Good vocal amp needed for small band rehearsals

Postby Wonks » Mon Jul 15, 2019 6:07 pm

Distortion will increase the amount of gain without increasing the volume level (by any noticeable amount), so there's really no point in going above a clean sound.
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Re: Good vocal amp needed for small band rehearsals

Postby Sam Spoons » Mon Jul 15, 2019 6:22 pm

Yup, I think that's the point CS70 was trying to make (it certainly was the one I was trying to make ;) ). :thumbup:
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Re: Good vocal amp needed for small band rehearsals

Postby The Bunk » Mon Jul 15, 2019 7:14 pm

Music Wolf wrote: Everybody, starting with the drummer, needs to turn down.

Some people think that you need to be loud to sound good. You don't. Playing loud just de-sensitises the ear so that you can't tell that you are shit.

Play at a comfortable level so that you can hear your mistakes - then correct them.

Bang on. For one reason or another, a band I was in took to rehearsing in my house, so we had to keep the noise down for the neighbours apart from anything but also just to be able to properly hear ourselves. They were the best rehearsals we had because you can actually, really, hear what the other guys are doing. The drummer just came along with one snare. The bass and one guitar was amplified to a minimal level and I (rhythm) usually played an acoustic. Vocal didn't need to be amplified...the human voice when belting it out, naturally, is loud enough.

In a rehearsal room/studio, we'd find that as we warmed up, someone, anyone, would get louder. The drummer would then get more into it and start playing naturally louder. Then I'd have to turn up to hear myself. Then the lead guitarist would do the same. Then the drummer would get more into it etc etc. Eventually it was a bloody mess and we'd all come out with ringing ears. And then pay £40 for it all and not be able to get to sleep for quite a few hours.
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