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anonymous 15 January 2009

Hi all,

I'm looking for a powered mixer for my ceilidh band. 6 channel and the ability to isolate the phantom power to a few channels.

Seen this:

http://www.reddogmusic.co.uk/PA-and-Live-Sound/Live-Mixers/Powered/Behringer-PMH1000.html

I presume "switchable +48 V phantom power" means you can switch it off channels that don't need it?

I haven't seen anything else in that sort of price-window that can do this. Does that mean I should really splash out and this one's pretty poo? We're not after AMAZING sound, it's basically just loud music to dance to.

Thanks for any input :)
Keith

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Comments

anonymous Thu, 01/15/2009 - 04:47

switchable phantom power typically means that you can turn it all on or all off. Not on a per channel basis. Why do you need to turn it off per channel? It's only on the XLR jacks, and almost all microphones don't mind phantom power. (The call it phantom because if you don't need it, you don't even know it's there.)

The only time I have had an issue is when I was doing something weird like splitting a microphone and running it to another mixer. Or once in a pinch I connected a direct out from one board into the XLR of another that had phantom power on. (that made a pop and a big repair bill)

Boswell Thu, 01/15/2009 - 05:09

Hi Keith,

Switchable phantom power doesn't usually mean individually switchable per channel. Powered mixers tend to have globally switched PP, and you have to go to much more expensive mixing consoles to get it. I don't know of a powered mixer that has that facility.

Why do you need the facility? I assume you know it's OK to use dynamic mics with PP enabled (not advised with ribbons, though), so I suppose you must have synths, keyboards or amplifiers with built-in DI that have XLR outputs that you don't want phantom power to get to.

Two solutions then: (1) 1:1 isolating transformers for these sensitive channels. These pass the signal but block the d.c. phantom power. (2) find a powered mixer that has both TRS and XLR inputs for each channel but where the TRS input is not padded by 20dB. Use XLR to TRS cables for these inputs. However, if your sources are synths etc, then level should be adjustable such that a 20dB pad is not a problem, and the TRS inputs on most powered mixers would work.

I would personally steer clear of the PMH1000 or anything else from that particular manufacturer. If you want a unit that will withstand a fair amount of knocking about, then Peavey has a good name for that type of use.

anonymous Thu, 01/15/2009 - 09:24

Hmmm, ok thanks for the replies. Yea I see what you're saying, I must be looking for something far over our price-range! The problem we encountered was a buzzing from our accordion when PP was switched on.

I don't know why it happened but when PP was switched off and we used a separate PP unit for the 2 mics (the flute and the violin) the sound disappeared. You're right, we also have an electric piano.

Flute - Audix ADX10-FLP condenser.
Violin - audio-technica ATM350 condenser.
Accordion - K&K Accordion Mic System. http://www.kksound.com/accordion.html
ePiano - MIDI out I presume.
Drums - unmic'd.

We currently have the PP unit for the flute/violin (XLR) with the piano being plugged straight into the mixer. The accordion is also TRS (same as 1/4 jack, yes?) in.

At the moment there is one out and we have 2x SRM 450s in daisy chain. Probably not the best way to do it, but at the moment it's the only way, our 17th century mixer has one main out only.

Let me know if I haven't explained things correctly, I'm not very good with the jargon.

So...we need a new mixer, just a regular one now by the sound of it, PP, 6 channels. I may be getting it wrong, but is the preamp what powers the mic using phantom power? Or is PP the thing that powers the mic and the preamp only boosts the signal? Or is boosting the signal and powering the amp the same thing?

Thank you for your patience. If there was a way I could repay you it would be done :)

TheJackAttack Thu, 01/15/2009 - 11:53

callmeKeith wrote:
So...we need a new mixer, just a regular one now by the sound of it, PP, 6 channels. I may be getting it wrong, but is the preamp what powers the mic using phantom power? Or is PP the thing that powers the mic and the preamp only boosts the signal? Or is boosting the signal and powering the amp the same thing?

So here are some simplified definitions to help you out.

preamp-this is what raises your microphones (powered or unpowered) to line level signal.

phantom power-dynamic microphones do not need this but other microphones require power to actually operate. Phantom power is what makes these mic's function. Phantom power should not be available or active on a 1/4" jack.

amp-is a separate stage of your mixer from the mic preamp side. This main amp is what drives your PA speakers. It takes the line level signal and amplifies it.

TRS-is a 1/4" (or 1/8") phone plug or jack that has a tip ring and sleeve. It is a balanced connection.

TS-is a 1/4" (etc) phone plug or jack that has just the tip and sleeve-no ring. It is an unbalanced connection. Most jacks on a cheap powered mixer are these. Also, according to the specs on your accordian mic's, this is the proper cable for that preamp.

Signal flow is all gozinta and gozouta. Instrument gozinta the mic. Mic gozinta the cable. Cable gozinta the preamp/channel. preamp gozinta (in your case) the mains. Mains gozinta the amp. Amp gozinta the speaker cable gozinta the monitor.

You get the picture.

anonymous Thu, 01/15/2009 - 12:19

Is this the way you have it set up?

Flute - Audix ADX10-FLP condenser --> XLR on mixer
Violin - audio-technica ATM350 condenser. --> XLR on mixer
Accordion - K&K Accordion Mic System. --> mono 1/4" cable to 1/4" on mixer
ePiano - MIDI out I presume. line out --> 1/4" on mixer

I can't see why turning on the phantom power would make a buzz caused by the accordion because there is no phantom going to it.

...Oh wait what is the manufacture of the powered mixer? (just kidding)

dvdhawk Thu, 01/15/2009 - 13:13

Hi Keith,

Have you considered this one? Soundcraft's Gigrac line is a little more costly, but I think you will be much happier with the integrated (Crown) amps section and Lexicon FX. The rack/case is a nice touch too.

It does have a global Phantom Power switch. I don't think I've seen anything in this class with individual PP switches on each channel.

http://www.reddogmusic.co.uk/PA-and-Live-Sound/Live-Mixers/Powered/Soundcraft-Gigrac-600.html?osCsid=t4a6vto8f2v5tor1kf4stnbhu1

And like some of the previous contributors, I'd recommend you check your cables to make sure you've got the right XLR / TRS / TS connections. From what I see on you KKSound specs, the accordian is a standard TS 1/4. Using TRS connectors would force the preamp to try to balance it.

Best of luck!

anonymous Thu, 01/15/2009 - 17:09

GeckoMusic wrote: Is this the way you have it set up?

Flute - Audix ADX10-FLP condenser --> XLR on mixer
Violin - audio-technica ATM350 condenser. --> XLR on mixer
Accordion - K&K Accordion Mic System. --> mono 1/4" cable to 1/4" on mixer
ePiano - MIDI out I presume. line out --> 1/4" on mixer

I can't see why turning on the phantom power would make a buzz caused by the accordion because there is no phantom going to it.

...Oh wait what is the manufacture of the powered mixer? (just kidding)

Flute mic -> XLR -> PP unit -> XLR -> mixer
Violin mic -> XLR -> PP unit -> XLR mixer
Accordion -> TS 1/4" -> mixer
ePiano -> phono out (TRS by the sound of it) with 1/4" jack -> mixer.

Sorry Remy, I didn't understand much of your post. We have no amplifier, only powered speakers? Ground loop? Ground lift? I understand the transformer bit though :) We don't have one.

Squeezebox indeed ;)

That mixer's a bit more expensive than I'd anticipated paying.
PP on inputs 1-4 only.
PAD buttons for loud inputs? What does this mean? And what sorta things is this used for?

edit:http://www.reverb-store.co.uk/product-detail.asp?prod=3293
Yes, discount. Interesting :)

Thank you again

anonymous Thu, 01/15/2009 - 17:49

callmeKeith wrote: ePiano -> phono out (TRS by the sound of it) with 1/4" jack -> mixer.

This is a problem, but not the cause of the buzz. A head phone jack has left and right signal on the tip and ring. These are in phase. A balanced TRS line signal has the rip and ring out of phase. The mixer will invert the out of phase signal and add it to the in phase to eliminate any noise that may have been induced on the cable. When you connect a head phone out to a TRS the right channel is inverted and added to the left. The result is that the center disappears! And of course, the center is where the bulk of your sound is. So you are left with a very weird sounding piano.

Either use a line out of the piano, or a 1/4" TS cable from the head phone output instead of a TRS cable.

Codemonkey Thu, 01/15/2009 - 19:31

Late in here, but ...
Our Phonic K-16 has per-channel Phantom Power (ain't we special).

£600 new, now discontinued though.

"This subject's a mine-field lol!"
Well, PA guys don't spend years slogging away for nothing. It's to cram all the factors into their heads so musicians can get on with concerts and paying us to do it for them :twisted:.

Boswell Fri, 01/16/2009 - 05:02

Keith,

A simple (and relatively inexpensive) thing to try first is to get a PASSIVE DI BOX for your accordion. This is a transformer whose output connects to an XLR mic input and whose input can be a guitar pickup or other unbalanced source such as the little mixer amp that is part of the accordion mic pack.

Use a guitar lead (TS -TS jacks) to connect the accordion mixer box output to the passive DI box input and a mic lead (XLRF - XLRM) to connect the DI box output to a mic channel on your mixer. The passive DI box does not care whether phantom power is enabled on the mixer or not. You may have to adjust the relative settings of the accordion mixer amp gain and the input gain trim on the mixer to get the best sound, but this configuration should solve your noise and phantom power issues with your existing rig.

Transfomer-based passive DI boxes can be had for about £15 -£20. Have a look at Ebay (UK) items 370142061878, 140294302090 or 120312817772.

After you have got this working, sit back and take a bit more time to work out what you really need in order to replace your present rig.

anonymous Fri, 01/16/2009 - 09:53

+1 for the Soundcraft Gigrac. I have the 1000 ST which I use for a small vocal PA. It's a decent little mixer amp and good value. It can be split with one channel of the amp for FOH and the other half for foldback, or can be run in stereo. 4 channels have phantom power. All have combined XLR / jack inputs and IIRC a couple have phono ins as well. The onboard FX are half decent too. It's a capable all round handy unit to have and comes in a handy carry case. Jeez, I sound like an advert for Harman here.... I don't work for them or have any affiliation!

Codemonkey Fri, 01/16/2009 - 20:09

Ah... our desk does have 14 mic inputs though, and there's a smaller version available. The £600 was also about 2 years ago.
The preamps are weak though.

A ceilidh band came to our church one time and had one of those small powered mixers that come in a small fat box (we have one too) and they're easy to use, and designed for this purpose.

anonymous Sun, 01/18/2009 - 06:18

IIRs wrote: [quote=dvdhawk]Keith,

Can you clarify something for me...

If you've got the self-powered Mackie SRM-450 speakers, why are you buying a "powered mixer"? To power monitors?

dave

I was wondering the same thing... :?:

Really just to give us more options in the future. There may be monitors and I fancy micing drums at some point. Having PP will let us power the condenser overheads?

IIRs Sun, 01/18/2009 - 10:32

callmeKeith wrote: [quote=IIRs][quote=dvdhawk]Keith,

Can you clarify something for me...

If you've got the self-powered Mackie SRM-450 speakers, why are you buying a "powered mixer"? To power monitors?

dave

I was wondering the same thing... :?:

Really just to give us more options in the future. There may be monitors and I fancy micing drums at some point. Having PP will let us power the condenser overheads?

I think there is some confusion here: a "powered mixer" usually means one that has built-in power amps in order to directly drive passive speakers. You have active speakers so don't need amps: what you need is just a mixer. Check out the Mackie Onyx range, I think they all have per-channel phantom.

dvdhawk Sun, 01/18/2009 - 12:40

IIRs wrote: [quote=callmeKeith][quote=IIRs][quote=dvdhawk]Keith,

Can you clarify something for me...

If you've got the self-powered Mackie SRM-450 speakers, why are you buying a "powered mixer"? To power monitors?

dave

I was wondering the same thing... :?:

Really just to give us more options in the future. There may be monitors and I fancy micing drums at some point. Having PP will let us power the condenser overheads?

I think there is some confusion here: a "powered mixer" usually means one that has built-in power amps in order to directly drive passive speakers. You have active speakers so don't need amps: what you need is just a mixer. Check out the Mackie Onyx range, I think they all have per-channel phantom.

Keith,

Since you're already invested in self-powered PA speakers, you could save yourself a lot of money (or put the same money to better use) by purchasing a regular non-powered mixer. As IIRs said, you need to make sure you understand the difference between a "mixer with phantom power" and a "powered mixer" . Don't plunk down your money until you do. I'd hate to see you spend more than you need to, or worse yet, buy something that you'll regret and have to replace right away.

anonymous Sun, 01/18/2009 - 22:35

Ah, once again, I'm being confused. So powered mixers have an amp built in to boost the signal for use through speakers without amps (passive speakers?). And phantom power is power to make the condenser mics work. Think I got it.

So this would do instead of the Gigrack 600, yes?:
http://www.reverb-store.co.uk/product-detail.asp?prod=3284

£90 cheaper than the '600.

dvdhawk Sun, 01/18/2009 - 23:23

Hi Keith,

You got it, you are exactly correct with your definitions.

And the little Soundcraft EPM8 you linked to is a great little mixer! Or you could look at the Soundcraft EFX if you like the idea of built-in Lexicon reverb and delay. In my opinion, both are miles ahead of the Behringer in sound quality. And no sense paying more for the Gigrac if you don't need the internal amplifiers.

Codemonkey Mon, 01/19/2009 - 12:24

Boost to me is like adding power to a mic signal, bringing it to line level.

Yes, you're right in saying the amp boosts the input signal, but it's like saying that going from Be**inger to a ViPre makes a "noticable" difference. True, but doesn't convey the scale.

It's like saying Buckfast is an undesirable drink. True but in reality it deserves stronger words. Buckfast is actually a stinking heap of .... You get the impression.

anonymous Mon, 01/19/2009 - 18:39

dvdhawk wrote: Hi Keith,

You got it, you are exactly correct with your definitions.

And the little Soundcraft EPM8 you linked to is a great little mixer! Or you could look at the Soundcraft EFX if you like the idea of built-in Lexicon reverb and delay. In my opinion, both are miles ahead of the Behringer in sound quality. And no sense paying more for the Gigrac if you don't need the internal amplifiers.

Been looking at that mixer again and unlike the Gigrac, there's no way to have PP on some channels and off on others. Hmmm, not that it's a necessity, it just makes setting up a bit easier. I need simplicity :lol:

Codemonkey wrote: Boost to me is like adding power to a mic signal, bringing it to line level.

Yes, you're right in saying the amp boosts the input signal, but it's like saying that going from Be**inger to a ViPre makes a "noticable" difference. True, but doesn't convey the scale.

It's like saying Buckfast is an undesirable drink. True but in reality it deserves stronger words. Buckfast is actually a stinking heap of .... You get the impression.

So, 'boost' is an under-estimation then. Line level? Is that after the preamp? It's late so I'm not thinking straight much.

Good 'Bucky' analogy btw! I enjoyed it. Not the Buckfast... :shock:

Codemonkey Mon, 01/19/2009 - 21:20

"So 'line level' is a standard that is equal no-matter which source is being used?"

Someone will say "I wish".
Line level means that the input is going to be a certain voltage, so arguably yes, it is a standard. But there are differrent references, I believe. +4dBU, -10dBV... (note that its U and V).
There's a sticky in a forum somewhere that explains these better.
Aha! {old-link-removed}

Regardless... (UK analogy) Mic level is like B class roads. Line level is like A class - designed for more traffic (voltage). Speaker level varies on the amp and is like a motorway.

Boswell Tue, 01/20/2009 - 04:51

Loosely, "line level" inputs are designed to take the output of other equipment such as pre-amps, hard disk recorders etc, and are not usable with microphones, instruments (guitar pickups) or other low-output devices.

Originally, "line level" refered to a +4dBm signal, which develops a power of approximately 2.5mW in a 600 Ohm load. Since this is a measure of the heating effect, it is a quasi-long term measurement. The corresponding voltage is 1.228V rms. When this voltage level is used into a high impedance (instead of 600 Ohm), the convention is to use the unit of dBu (u = "unterminated"), so +4dBu is an rms level of 1.228V. The peak level with normal music can be 20dB greater than this, hence it is advisable for equipment to be able to handle +24dBu on their line inputs before clipping. Not all equipment can do this...

dvdhawk Tue, 01/20/2009 - 16:55

Hi Keith,

The Phantom Power is "globally switched", on both the Gigrac and the EPM mixer. Which means, it is either on for all the XLR channels or off for all the XLR channels. A dynamic mic that doesn't need the Phantom Power will just ignore it. Direct boxes will filter phantom power out of any device that doesn't need it. So I wouldn't worry about as much as it seems to concern you. Have you investigated using a direct box to connect the accordian as others have suggested?

Best of luck.

anonymous Tue, 01/20/2009 - 18:08

Hi guys,

Code, Greener and Boswell - No idea what you're talking about. That link doesn't help me much either. Is there a recommended reading list of sorts? I don't want to continue hassling you all with n00b questions if I can read up on stuff myself.

dvdhawk: The Gigrac has PP on channels 1-4, but not 5-8. I will look at the direct box option, yes :)

Thanks again, e-hi 5s all round!

anonymous Wed, 01/28/2009 - 14:30

OK, here's what happened...

I ordered a Gigrac 600 online from Reverb with the assumption that it would be delivered relatively soon as it was in stock. We needed it for last Saturday but by the Thursday it still hadn't arrived :/ I didn't even have an email to confirm anything and no returned calls! Not good.

Anyway, I phoned their Glasgow store and got them to hold the one '600 they had and travelled through on the Saturday afternoon. I got shouted at though because apparently powered mixers don't work with powered speakers. I have a pair of Mackie SRM 450s.

So now we have a Soundcraft E8
http://www.reverb-store.co.uk/product-detail.asp?prod=1149

They didn't have much stock (and couldn't have a Yamaha mixer apparently?! Display stock, psh!) so this was the only thing we could feasibly have. They said PP won't interfere with anything that doesn't need it (the piano and accordian).

We saved £50 and it worked a treat. Simple setup and easy to tweak during the set. It's 1024 times better than the last thing we had so we're happy.

Thanks for all your help guys, learning curve's pretty steep but it's all good at the moment :)

Keith

anonymous Thu, 01/29/2009 - 02:08

IIRs wrote: [quote=callmeKeith] I got shouted at though because apparently powered mixers don't work with powered speakers. I have a pair of Mackie SRM 450s.

We already told you that. :roll:

I wasn't aware that it wouldn't work though, I only thought it was a bad idea because powered mixers are more expensive. Either w ay, lesson learned.

What would have happened if I used a powered mixer with the 450s?

Codemonkey wrote: Note to self, Reverb's Glasgow store are idiots.

I was going to buy a Samson S-Com off them, don't want to be having terrible service if it fails.
At least I don't have to worry about delivery costs :P being local that is.

And I suppose you know how to navigate the 1-way system too? Uhg, took us ages to get from the M8 to Jamaica Street :x

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