A Weird PA Problem

[Mandobart]

I play all my instruments thru a K&K Pure pre-amp. Has a single 1/4" input (from the instrument) and a single 1/4" output to PA, amp, whatever I use. Powered with a 9 VDC battery. Does not have a bypass function. Been using this for over a year. Had a couple of St Pat's gigs, so I changed out the battery (usually do that every month anyway). At a local gig on Thursday, where I've often played before thru this exact rig and the house PA, I could get no sound (the PA was getting no signal). Swapped chords, etc., nothing. Plugged straight into the same PA channel with no preamp or DI and it worked; just didn't sound as good (impedance mismatch). The next day at home I was checking everything out using my old Peavey 130. Everything worked fine (cords, pre-amp, amp, instrument pickups, all good). Took instruments, preamp cords and Peavey to play first gig last night (playing thru my amp and not a PA). No problems on both mandolin and fiddle. Go to the next gig where I'm playing with my pre-amp thru a different house PA (left the Peavey amp in the truck); have the same problem as I had on Thursday, plus now when I plug straight in I still get no sound thru the PA. I use good quality mono 1/4" cords. In both cases (Thursday and last night) this was not an intermittent problem; the PA was getting no signal. I should have paid more attention to the brand/model of PA as that would be good info for troubleshooting. Anyone have a similar issue ever come up? Thanks.

[Charlieshafer]

Couple of things first off, which may or may not be it. I wish you'd tried an XLR out of the pre-amp into the board, and perhaps with a DI just to make sure the signal was getting boosted, though this would possibly have been overkill with the pre-amp. It's possible the board was not selecting the 1/4 inch input for some reason, though it should be automatic. On some boards, there are also selector buttons for different features, like panning left/right, etc. If one of these was depressed, it could be sending the signal to a different group on the board, which ended up dead-ending as no one knew to select that group or bus. Tough to say without all the associated info of the exact board, but might be the issue. In general, good PA boards like XLR inputs., so as a long-term issue it might be wise to fine tune the equipment to an XLR out when using a board.

[foldedpath]

Going along with Charlie here, my guess is operator error, even though it happened with two different house PA systems.

Most larger house PA mixers have line-level inputs on their 1/4" jacks. If you're not feeding the mixer an actual line level signal (and you're not, with most battery-powered preamps), then it may be too weak to hear. Especially if the PA operator has left the input gain set for the last line level input source that was running through that channel.

A good house PA engineer will look at what you're doing on the other end of the cable, then slap a DI on your 1/4" battery preamp output and run it into a mic channel on the mixer. But you can't always count on that.

If you're using the version of the K&K Pure that doesn't have an XLR output, then you might need to carry a DI box for this type of situation. Or upgrade to that preamp version.

Or... it could be something else that's causing the problem. But I'll bet it's related to handing the house PA operator a 1/4" cable and assuming they know what to do with it.

[Willie Poole]

If the PA is set to inputsfrom a mic the input from a preamp might not be the correct impeadence and you get nothing, There should be a switch to be able to select one or the other....I could be a better "fixer" if I could see all if the equipment....I have ran into a problem where the building I am playing has a real low voltage and not enough to work the Pa head....Most of the newer PA`s need at least 109 volts or so I have heard....

[Tom Wright]

Least-expensive PA-compatibility item would be a Shure inline transformer. Normal 1/4" out from the K&K into the transformer, XLR out from that to PA.
http://www.bhphotovideo.com/c/produc..._Matching.html

[Tim2723]

Yeah, all and any of the above. Most likely just operator error, like accidentally muting a channel without knowing it. Always have every adaptor, connector, transformer, etc in your bag if you play out and around with lots of different gear. Be ready for anything. From time to time I like to go into Radio Shack and just have a field day. I can connect anything ever made to anything else. I have an adaptor that connects BNC to RCA. Never used it in forty years, but by God I have it!

[llg]

I second and third the previous suggestions. Always a good idea to have your own adapters...Also know that a lot of guys that run house PA know very little about actually running sound systems. Most I've seen know how to push faders up and down, that's it. They know very little about impedence, matching ohms of speakers with power amps, eq etc. It ain't rocket science but it's also more complicated than it looks, too. I would recommend reading "Live Sound Reinforcement" or "Sound Reinforcement Handbook" to learn the basics (there is some really technical stuff in there as well) but if you learn the basics you'll already know more than most local house PA guys. You can order these books thru Elderly (or at least I did several years ago.)

[jmarshall58]

As an ex-pro sound guy (25 years doing coliseums, auditoriums, and stadiums) yeah, sometimes it can be rocket science but usually operator error. Mixing boards over the years have become more and more complex and most operators at small venues simply do not understand them. I have found this most true with churches. I will second the suggestion to have connectors for any occasion. As an afterthought, I have used BNC to RCA but only for video.

[llg]

I totally agree Jim. Most festivals, churches, other small venues have very green operators running the board and it can get rather touchy if suggestions are made to change anything. They don't know much, but they do know it's their board and their seat and they ain't giving it up. With that being said there are exceptions...we have a guy that lives here in middle Tennessee that does a lot of BG festival sound and he is excellent. That, however, is rather rare.

[allenhopkins]

OK, in the first instance it wasn't that the channel was switched off, because you got signal when you took the pre-amp out of the chain. Also wasn't low signal strength, 'cause your signal should have been higher with the pre-amp. The second instance, could have been an accidentally muted channel, or lack of signal strength.

If you have the option, plug into a different channel on the PA, see if you get the same result. This will ID a muted channel, or one that needs to be manually switched from XLR to quarter-inch, and hasn't been.

Second the idea of putting a DI into the signal chain, and using XLR connectors. If a PA's being used 99% for mics and DI's, only the XLR sockets, it can have a bad quarter-inch socket or a bad wire to the socket and the normal users will never know until you plug in your cord.

But, still puzzling about the first instance. You got signal without the pre-amp, but no signal with the pre-amp, which does point to a problem with the pre-amp.

[Ben Milne]

You haven't mentioned what kind of pickup you're using.
Check you're seating your 1/4 inch connectors completely. I often use the red neutrik jacks, but the little springy bit can stop them being seated correctly.
Plug into a tuner and confirm that your instrument is outputting.
Use an active DI, preferably one with an indication that phantom power is present, and no pads are engaged.

[Tom Wright]

Just remembered that on the K&K the battery is switched by plugging into the output jack (annoying non-conventional setup). This could mean that someone tried to use a tip ring sleeve cable (TRS), which would perhaps run afoul of the battery switch, perhaps leaving the preamp not turned on as a result. Alternately, if the PA guy plugged you he may not have pushed the plug in deep enough: it's a tight fit on my K&K.

And of course this does not explain the other PA failure.

[Mandobart]

Thanks to everyone for the info. Just to muddy the waters, I played through my K&K pure pre-amp into a Yamaha powered head PA last night at a different place and everything worked great (played both my fiddle and mandocello), using the same cords I used on the problem nights. Both of these instruments are equipped with twin head JJB piezo's. These are the same p'ups I have in all my regular players, installed myself (hey I need to get some use out of two years of USN electronics tech school you all paid for), and all have worked on several occasions using the same cords, same pre-amp and thru these same PA systems at both the recent "problem" places.

I've always used just standard 1/4" mono plug cords on my K&K. I double checked the connections at the instrument, pre-amp and PA board on both problem nights. I know the instrument(s) has an output as my personal amp never fails, and again they usually work, even on these problem systems.

I have a couple 1/4" to XLR adapters; if I plug the 1/4" into the pre-amp out and the XLR into the board, I'm wondering what would happen if the phantom power from the board tries to feed my pre-amp? Obviously I only have two wires on my mono cords (well one signal lead and a ground shield), so maybe it just leaves an open ckt on the XLR end. I'm pretty sure the pre-amp can boost the signal high enough to feed a board; again it usually always does.

I'm thinking that operator error or bad channel is the most likely scenario.

[almeriastrings]

I would invest in a simple DI box. Nothing too fancy required. This will take the unbalanced 1/4" jack from your K&K and convert it into a balanced XLR signal that you can plug straight into any desk. For example:

http://www.zzounds.com/item--ARTZDIRECT

This will avoid any potential phantom issues (which can arise with adapter plugs) and make things very simple and straightforward for whoever is in charge of the sound, even if they don't really know what they are doing....

[Ben Milne]

If you're using the version of the K&K Pure that doesn't have an XLR output, then you might need to carry a DI box for this type of situation. Or upgrade to that preamp version.

.

This. Use something with XLR output or use a DI.

I think the k&k stuff has some odd impedance things going on and tends to work best when married to equipment of it's own brand. (I have seen K&k guitar pickups freak out RX belpack units even when turned down to a third of their volume.)

If you want more control, LR Baggs and BBE offer preamps (Venue/paraDI and Acoustimax respectively) with plenty of EQ etc and have XLR out.

[mandotim1955]

I have a K&K mandolin twin in one of my mandolins, a Rigel pickup in another and a Baggs Radius on the Gibson. I play all of these through a Headway EDB-1 preamp, with no impedance or level problems whatsoever. I've just tried a couple of guitars through it with Fishman pickups; again, no problems. You can tweak the impedance levels for different pickups, and tune the EQ to suit instruments with different pitch ranges. Two channels, and a choice of XLR or jack ins and outs. The EQ is great, and it even has a notch filter, phase switch and a mute. No financial interest, just a fan of these great preamp/DI boxes.

[Tim2723]

As to the phantom power question: Phantom power only affects those devices that accept it, so don't worry about it. If a device doesn't run on phantom, it's just ignored.

The thing about modern mixing desks is that they have very small controls all crammed together in a tiny space. It's way too easy to push some little button by accident. I can turn something on or off without knowing it. Heck, I can hit three buttons at once with one finger. It's even hard to tell if a button is in the up or down position with a lot of these. Oh for the 70's and those big honkin' knobs!

[foldedpath]

As to the phantom power question: Phantom power only affects those devices that accept it, so don't worry about it. If a device doesn't run on phantom, it's just ignored.

For the record, there are a few devices that can be damaged by phantom power. It's always a good idea to check the manual first, on whatever you're using. For example, my G-Natural pedal includes this note:

WARNING! When connecting the G-Natural
outputs to microphone inputs on a mixing console,
the phantom power for these channels MUST be
switched off! Otherwise you may damage the
G-Natural circuits.

So it's rare, but damage can occur with some devices. With a basic DI box as an interface, it won't happen.

[almeriastrings]

Yes... I know someone who fried a $1200 ribbon mic because they forgot the phantom was on.....

[Ben Milne]

Theoretically, a ribbon should be fine with phantom, but yeah, all it takes is one incorrectly wired cable to cause heartache and wallet-burn. I try and turn it off whenever plugging into balanced line outputs of keyboards, bass heads, DJ consoles etc.

Anyone dealing with ribbons I would suggest using something like a Triton Fethead or Cloud microphones Cloudlifter. 20db boost of clean gain and they require phantom power while protecting your ribbons from copping voltage they don't want.

[Charlieshafer]

Anyone considering using ribbons in live performance sort of nuts, anyway. The fragility and cost are far even made more daunting by the lack of improvement in sound quality. This isn't a studio, it's a venue where the weakest link in the sound chain determines the quality of overall sound. From amps to speakers to room acoustics to problems like the one this thread started with, all render ribbons overkill. I know some people use them and swear by their sound quality, but it's a placebo effect when in live performance. Tried and true is always the way to go when you're charging people money, and these folks don't want to know about technical difficulties.

Back to the basics, here. DI and xlr cables to the board will make the equipment as bullet-proof as the board op will allow.

[almeriastrings]

Anyone considering using ribbons in live performance sort of nuts, anyway.

This was in in studio. Then again, a huge number of classic acts from the 40's and 50's used ribbons extensively live. Everyone from Flatt & Scruggs, to Sinatra, to the Beatles (with their old Reslo's). But of course, they did not have phantom powering on the desk to worry about...indeed, they didn't have a desk at all as we know it... or on-stage monitors.... or several hundred or even kW of power.....or anything else we have to contend with today. Life was simpler - and quieter!

[Tim2723]

Thanks for correcting my mistake fellas. I was unaware of that rare but important exception. My context is live applications where those issues seldom if ever arise. Thanks, and noted for future reference.

[Charlieshafer]

This was in in studio. Then again, a huge number of classic acts from the 40's and 50's used ribbons extensively live. Everyone from Flatt & Scruggs, to Sinatra, to the Beatles (with their old Reslo's). But of course, they did not have phantom powering on the desk to worry about...indeed, they didn't have a desk at all as we know it... or on-stage monitors.... or several hundred or even kW of power.....or anything else we have to contend with today. Life was simpler - and quieter!

Wasn't that the good old days of sound! The other aspect no one gives as much thought to is that how much stage spacing there was "back then." Many times the lead singer was way out front or separated from the band by enough space that there was no bleed through. The amps were set waaaaay back from the microphones. Too few people give much thought to stage volume and noise as a way to drastically improve the sound. It's funny looking back over 20 years of tech riders and see how many artists have de-tuned their microphone choice through the years. Recently, it's all sm58's for just about every larger ensemble, and that includes groups like Solas, which are very vocal-dependent. Only to 2-3 person groups who really hold to the single mic ethos use the condensers.

yeah, I'm wishing the tech lists were a lot simpler, too!

[almeriastrings]

The good old days... I know we are straying a bit OT here... but if you are a into the history of recording and audio stuff, this website is just wonderful to browse:

http://www.philsbook.com/abbeyroad.html

Some of the old photos are simply amazing. Really brings home to you just how much as changed. For the better? Debatable! In specification terms, possibly, but heck, they caught some classic sounds then that today people spend a fortune trying to emulate with plugins, unlimited tracks, high bit-rate A/D conversion and suchlike...

It would be great if there was a similar resource on the old Nashville and NY studios... anyone know of one?