Ringing Out The Room - Channel or Overall PEQ?

Dick,

If you’ll be objective for a moment, you are the one who started this “battle” by taking me to task for things you misinterpreted. You just made incorrect assumptions about what I was saying. You said I wanted an argument, but you are the one who started the argument.

Perhaps, as you said, I didn’t express myself in terms or vernacular that you’re accustomed to. But the proper approach would have been to simply answer the OP’s question in your terms, not berate me for trying to be of help. You even took me to task for not using simple sentences! Just why is it that you feel the need to berate everyone?

Is it even possible that there may be some gaps in your knowledge? I’ve never met anyone who seems to think he knows it all, as you seem to. Might there be anything in this field where you have misconceptions? Is it even possible that you could misunderstand what someone has said?

I am impressed by what you appear to know about audio, but how is it that you have established yourself as the most astute individual on this forum?

I really hate it when I seem to have made an enemy – that was never my intent. I suspect that you may have some psychological issue that you need to face. Think about it. Just what is your problem?

Please everyone CHILL OUT :slight_smile:
I have now read Dick’s document and it was both interesting and helpful, so many thanks for that.

I would suggest you guys kiss and make up or I would recommend to the moderators to take down this thread. I would hate to see that. It is a great place to learn. Sure we all have our own skill sets and knowledge base but we need to be civil in expressing our opinions. I have been in this industry in some way darn near 50yrs now. Started when I was a teenager. I have done just about everything you can imagine. I feel very lucky. I am pretty much self taught. I never claim to have the level of knowledge that both of you seem to on the science. I understand most of it but have just never dug in that deep. Mine is mostly practical knowledge from having done it a lot. i just try to help out folks if the subject is something I feel I know or have experienced. I never want to be portrayed as an ‘expert’. I don’t think any of us know it all.

I’ve been playing around with my PA in my garage today (Ive now put it in my house which I’m sure the neighbours are going to love) getting it to feedback/resonate and attempting to sort it by both the overall PEQ and GEQ.
I must admist I’m finding it a lot easier to do with the GEQ at the moment.
I’ll keep at it though.
Cheers for the advise everyone.

Just remember. That will change with every venue. No two the same.

What makes the PEQ little more difficult to use is finding the correct center frequency. As already stated many times the bands of the GEQ (as it is integrated inside the Qu) are much wider, so you’re operating more with a broom than a tweezer. The integrated RTA isn’t precise enough telling you the correct center frequency either. Try to feed a sine (from the signal generator, for example) to the RTA and you’ll see a bell shaped response of the RTA, not a single peak (see below).
You have two options finding the PEQ frequency. The loud variant is using a narrow Q, rising the gain on the band a little and sweeping the frequency to the right spot. Take care of your ears and neighbours, …not recommended!
The more clever approach is using a better (higher resolution) RTA which directly displays the frequencies of peaking bands. You may even determine problematic frequencies before you hear feedback. I’m using the 1/24 octave version of TrueRTA which I registered years ago before smartphones exist. I guess nowadays you will find a nice app.

The reason for the bell shaped response of the integrated RTA is based on its implementation. Obviously the Qu-RTA does not implement FFT (=high DSP load, slow for higher resolution) but more a peak detection on bandbass filters (=less DSP load, quicker response). A RTA suitable for feedback detection should do FFT calculation as TrueRTA does. Feeding a sine will show a single peak not a wide range.

Also be careful in ringing not to trash your HF drivers. I have seen it happen. Replace all EAW drivers in a church few years ago over that. Long sustained HF feedback trying to ring a system. Makes for ugly blackened coils.

The RTA reasonably matches the GEQ in width though IIRC from ringing out the church (I took in the QU for the siggen and RTA)

Just remember. That will change with every venue. No two the same.

Totally. I’m finding it all quiet interesting now to be honest.

It’s the techniques that stay the same.
PA positioning is first up on my list…

a very special thank for Dick’s PDF Document.

Very helpful und useable.

Great to send me this

Greetings from Germany (Klaus)

Hey guys
I found this thread both very informative but also sad. It’s great to debate about stuff and dispute things as that’s how we all learn. No one knows things without learning from someone else, unless they are a genius who discovers or invents things and doesn’t need anyone else’s input (don’t know many of them !!). I just wish DR and Doc didn’t insult each other. There is no need for that here. None of us knows it all. And as my long time ago maths teacher used to say " There’s no such thing as a stupid question". It might appear to be stupid to someone who has more knowledge, but to the person asking it isn’t. So please please be courteous and respectful to each other. I enjoyed the knowledge both Dick and Doc shared and it gave me food for thought. I love debates. I hate insulting arguments. Keep sharing…peace !!!

Just one small point of clarification I would like to make. It is confusing talking about a narrow Q, no such thing really. A narrow octave bandwidth relates to a high Q value and a low Q value is associated with a wide octave bandwidth. Q = (sq.rt (2 to power of N))/((2 to power
of N)- 1). where N = octave bandwidth
I know what you mean (well I think I do) in that by a narrow Q you mean a narrow octave bandwidth ??
Barry

Careful Barry, sounds like you are baiting D&D to start again?! :wink:

Bring it on…:slight_smile:

lol!

I thought I had posted this link earlier: “Q” vs bandwidth

Coincidentally, I’ll be providing recording and video camera audio feeds for a festival of community bands entitled “Bandwidth” in a couple of weeks.

DR

Barry,

Thanks for your clarification regarding my use of the term Q. I knew that I was not using perfect terminology, but I was trying to communicate the thought to those not familiar with the specifics. I should have just used the term “narrow bandwidth.” Q is also used when speaking of these filters, but many may not know what you mean when you speak of a high or low Q value. Your comment was appropriate.

Yes Doc i knew what you meant, my clarification was in no way a rebuff, it was just for the benefit of those who may not yet have known about this anf may have been confused. I live this topic, i.e. audio mixing…Cheers☺

Evenin’ All.
So, I had a good 6 hours with my band today on addressing this issue and I really don’t know how much further I’ve gotten with it.
While ringing the room (Both trying first with a mic on stage and then with a mic in the middle of the room) I identified/rang out to create feedback. I tried many scenarios.

I boosted frequences on the PEQ and droped the gain on PEQs with as narrow a Q as possible.
I boosted the channel volume and used an app called FFT PLOT that displayed the exact freqeuncy and then I dialed it down on the PEQ.

I tried it on both the main LR mix PEQ mix and each channel PEQ mix.
I also tried it on the main GEQ.

I tried it with one mic, I tried it with two mics.

Here are the issues I’m still experiencing:-
a) Far too many frequency issues (I ran out of PEQs)
b) Even if I managed to get one mic to no longer ring, the moment I tried to add a second mic into the equation I then had a load more frequencies to deal with from that second mic channel.

When do you STOP tring to deal with feedback frequencies due to there being so many of them?
How far up do you bother to boost a freqency to try to force it to feedback? If its very near the top, do you even bother trying to remove it?
How do I determine what are the MAIN freqency issues when there are so many?

As I say, I’m really unsure how much further I’ve gotten with this…It was a very tiring day and now I deserve a nice cold beer.

Your continued assistance in this matter is the only thing keeping me sain right now.

General rule has always been when you start having multiple Freqs feeding back it’s time to stop. Sounds like you have other things to consider as has been noted. Type of mics, speakers. Speaker placement. Etc. I do shows all the time. Rarely have feedback issues on vocal mics. If I do it’s from wedges. Not mains.