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SpectraFoo sound off July 14 2014 [message #86103] Mon, 14 July 2014 22:30 Go to next message
rabyn is currently offline  rabyn
Messages: 27
Registered: July 2014
Location: Planet Earth
Junior Member
Greetings Spectra Foo forum,

My name is ra byn (robin).

I have been using Spectra Foo Complete for live audio purposes for a few years now. I'm curious to know who is still active on this list. Specifically related to Spectra Foo (in case this post goes out to all MH forum members).

Consider this post a sort of Foo sound off.

Best regards,


ra byn (robin)
Re: SpectraFoo sound off July 14 2014 [message #86105 is a reply to message #86103] Fri, 18 July 2014 12:26 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
Junior Member
I'm just starting with 'Foo Complete, using it primarily for live sound analysis - tuning PA, etc. Very interesting app - loving it so far, but just scratching the surface.

Robert
Re: SpectraFoo sound off July 14 2014 [message #86106 is a reply to message #86105] Fri, 18 July 2014 21:30 Go to previous messageGo to next message
rabyn is currently offline  rabyn
Messages: 27
Registered: July 2014
Location: Planet Earth
Junior Member
Greetings Robert,

I'm curious about your experience with SFC so far. What I/O are you using with it? Any troubles getting it to serve the purpose you have for it? Which tools are you using? Transfer Functions only? What mic? Are you using more than 1 mic at a time? Are you using the internal loop function for measuring or using a hard out / in patch? Had in success with aligning subs with SFC yet?

ra byn (robin)


ra byn (robin)
Re: SpectraFoo sound off July 14 2014 [message #86108 is a reply to message #86106] Tue, 22 July 2014 12:04 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
Junior Member
Hi, Robin...

To answer your questions:

I'm using 'Foo with my beloved ULN-8.
As I said, I'm just 'scratching the surface' of "Foo, and am in the middle of experimenting with it's various uses. Just yesterday I did my first Transfer Function experiment, to attempt to tune my band's PA system. I found it quite confusing, but have confidence that I will 'get it' in time. The same was true (at the beginning) with MIO Console - at first, there were a lot of "Huh?" and "WTF!!" But now, it's clear that the MIO's extreme flexibility is worth a bit of a steeper learning curve. I have a feeling the same is true of 'Foo.

For the Transfer Function use, I'm using the great Josephson C617 Omni.

I'm such a 'Foo newbie, that I don't even understand your other questions, especially, the "Are you using the internal loop..." Like I said... "Huh?" and "WTF!!"

And lastly, no I've made no attempt to deal with subs yet. Still in the early phases of learning.

Without meaning to put you on the spot, might you entertain a question of two from me to help me better understand how to use "Foo? We can go off-forum for that if you'd like???

Best,

Robert
Re: SpectraFoo sound off July 14 2014 [message #86110 is a reply to message #86108] Tue, 22 July 2014 22:12 Go to previous messageGo to next message
rabyn is currently offline  rabyn
Messages: 27
Registered: July 2014
Location: Planet Earth
Junior Member
Robert,

Let's deal with the questions you have here.

I'll explain the internal loop idea in another post.

ra byn (robin)





ra byn (robin)
Re: SpectraFoo sound off July 14 2014 [message #86112 is a reply to message #86110] Wed, 23 July 2014 14:20 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
Junior Member
Excellent, Robin. Thank you... and here goes:

First (and most important) question/confusion:

I want to use 'Foo's Transfer Function to 'tune' my PA. I use 2 FOH monitors, and a bunch of stage 'wedges' for musician monitoring. For the sake of this discussion, let's forget about the wedges.

Since the Transfer Function wants the 'source' in one channel, and the 'response' in the other channel - only 2 channels are available - does this mean that all Transfer Function measurements must be done in MONO? In other words, must I treat each side of my PA (left and right) as different sources, and EQ them separately? And if I use some 'pop music' (as suggested in the 'Foo manual), must this also be made MONO before using the Transfer Function.

Or (very likely), am I missing something important here that makes the preceding paragraph nonsense?

Hope the question makes sense... and many thanks for taking the time to answer!

Ra Byrt (Robert)

[Updated on: Wed, 23 July 2014 15:54]

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Re: SpectraFoo sound off July 14 2014 [message #86114 is a reply to message #86112] Thu, 24 July 2014 00:12 Go to previous messageGo to next message
rabyn is currently offline  rabyn
Messages: 27
Registered: July 2014
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Robert,

Let me ignore your question about "mono" for a moment.

When you're tuning a sound system, ideally you will have the ability to control EQ, delay and level (including MUTE) to every speaker in the system. Most systems aren't that flexible. For example, you may have a bunch of front fills that are jumped from one to the next. In that case, you may have to unplug all but one to measure.

So making multiple measurements at the same time would be counter intuitive. IF I could have a second TF instrument, I might use it for measuring a secondary point in the same signal chain (for example, comparing the console output with the DSP output) but I would still be operating in "mono".

Snapshots and the overlay list serve to provide a way of comparing lots of things without doing it in real time.

If your PA is symmetrical and the venue is symmetrical, you can measure one side and perform corrections. Then copy those settings to the other side of the PA. Then verify they match.

If your PA is not symmetrical and/or the venue is not symmetrical, you will have to measure each side as it's own system.

Once I have corrective EQ in place, delay times are set and levels are sketched in for all subsystems, I'll use music to walk around. I may send pink noise to the entire system and measure again. This is to see what the whole system does together (which might reveal a build up of low / low mid energy) that wasn't apparent measuring sub systems of the PA. It's at this time that it's helpful to be able to mute / unmute subsystems to see what is causing any build up.

Once I am past the EQ / Delay / Level stage, I don't use the TF tool any more. Instead I run the Spectragram Instrument to catch any feedback that may occur.

If this makes no sense, I'll try again.

ra byn (robin)


ra byn (robin)
Re: SpectraFoo sound off July 14 2014 [message #86118 is a reply to message #86114] Fri, 25 July 2014 10:42 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
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Great, Robin. Your descriptions are very helpful. I'll be doing a bit more 'experimenting' this weekend.
Thanks very much for the explanation - it makes perfect sense to me!

Robert
Re: SpectraFoo sound off July 14 2014 [message #86120 is a reply to message #86114] Fri, 25 July 2014 13:17 Go to previous messageGo to next message
bj is currently offline  bj
Messages: 412
Registered: July 2011
Senior Member
rabyn wrote on Thu, 24 July 2014 00:12
Once I have corrective EQ in place, delay times are set and levels are sketched in for all subsystems, I'll use music to walk around. I may send pink noise to the entire system and measure again. This is to see what the whole system does together (which might reveal a build up of low / low mid energy) that wasn't apparent measuring sub systems of the PA. It's at this time that it's helpful to be able to mute / unmute subsystems to see what is causing any build up.


I would like to make one comment about this -- it is important to set the delay times for coherent elements of the system before measuring and EQing. While it is perhaps less important for things like fills (but I would still time-align first), it is critical for things like the high, mid, low, sub alignment.

The time alignment between the coherent drivers must be done before EQ measurement and correction, because there is interaction between the bands. If you EQ first and then time-align, all the EQ for the interaction regions of the frequency response will change when you time align, and either your EQ will be off, or you will need to re-measure and re-EQ.

So it is best to do the time-alignment first and then do the EQ.

Re: SpectraFoo sound off July 14 2014 [message #86121 is a reply to message #86120] Fri, 25 July 2014 13:42 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
Junior Member
Thank, Robin...

Very clearly explained and, luckily, this is what I've been doing in my 'learning experiments.'

Best,

Robert
Re: SpectraFoo sound off July 14 2014 [message #86127 is a reply to message #86120] Sun, 27 July 2014 18:44 Go to previous messageGo to next message
rlhinc is currently offline  rlhinc
Messages: 9
Registered: July 2014
Junior Member
Hi, Robin...

If you're willing to keep this thing going... I've got some questions: I've been working on the Transfer Function function (!) in 'Foo, and it's going pretty well. I've successfully gotten to the point where I'm attempting to EQ the source material to compensate for PA and room, etc. All looks just like the illustrations in the 'foo Manual.

However, when I 'lower' the waveform 'snapshot' according to instructions (to make the EQ an 'all cut' EQ), I seem to run into trouble. I'm using the 12-band mono EQ in my +DSP ULN-8, but having a hell of time trying to 'match' the inverted waveform snapshot. The concepts are all clear, but I wonder if you have any advice with regard to making this work better:

First, I'm not really sure how close I'm supposed to get to the inverted snapshot waveform. Even with a 12 band EQ (with lots of Q control, etc.), I'm finding it very difficult to match the inverted waveform. So far, my attempts at corrective EQ sound pretty bad.

Mostly, I'm not 100% sure that I'm supposed to really 'match' the inverted snapshot waveform - I've actually been trying to make my EQ curve literally 'match' the snapshot - is that correct?

I'll go for one thing at a time, so as not to overload you... but there are a few more dumb questions!

Thanks, Robin... you've been very helpful!

Robert
Re: SpectraFoo sound off July 14 2014 [message #86128 is a reply to message #86127] Tue, 29 July 2014 16:13 Go to previous messageGo to next message
rabyn is currently offline  rabyn
Messages: 27
Registered: July 2014
Location: Planet Earth
Junior Member
Great question Robert!

Basically you get rid of the large peaks and plateaus. Flat is relative. Take some screen shots and post them here. Before and after your compensation eq. I've been told by measurement engineers that if you need more than 6 filters, revisit your speaker choice, acoustic treatment, speaker placement, aim, etc...

If you see huge holes, that may indicate issues that need to be fixed before you eq. For example if the low/high xover is configured wrong, there might be excessive or diminished frequency content at overlap.

One of your first clues is indicated by performing "compute delay" which provides a visual indication of reflections and polarity. If you see multiple peaks, you are either measuring more than one speaker or there are reflections. Either mute or figure out how the reflections are being created.

Once I'm out of the sticks, I'll post some before and after screen shots of my successful eq attempts.


ra byn (robin)
Re: SpectraFoo sound off July 14 2014 [message #87116 is a reply to message #86108] Mon, 06 May 2019 18:51 Go to previous messageGo to next message
RAILITY is currently offline  RAILITY
Messages: 5
Registered: May 2019
Location: france
Junior Member
rlhinc wrote on Tue, 22 July 2014 12:04
Hi, Robin...

To answer your questions:

I'm using 'Foo with my beloved ULN-8.
As I said, I'm just 'scratching the surface' of "Foo, and am in the middle of experimenting with it's various uses. Just yesterday I did my first Transfer Function experiment, to attempt to tune my band's PA system. I found it quite confusing, but have confidence that I will 'get it' in time. The same was true (at the beginning) with MIO Console - at first, there were a lot of "Huh?" and "WTF!!" But now, it's clear that the MIO's extreme flexibility is worth a bit of a steeper learning curve. I have a feeling the same is true of 'Foo.

For the Transfer Function use, I'm using the great Josephson C617 Omni.

I'm such a 'Foo newbie, that I don't even understand your other questions, especially, the "Are you using the internal loop..." Like I said... "Huh?" and "WTF!!"

And lastly, no I've made no attempt to deal with subs yet. Still in the early phases of learning.

Without meaning to put you on the spot, might you entertain a question of two from me to help me better understand how to use "Foo? We can go off-forum for that if you'd like???

Best,

Robert

I have been using Spectra Foo Complete for live audio purposes for a few years now. I'm curious to know who is still active on this list. Specifically related to Spectra Foo (in case this post goes out to all MH forum members).
Re: SpectraFoo sound off July 14 2014 [message #87128 is a reply to message #87116] Wed, 08 May 2019 13:18 Go to previous message
bj is currently offline  bj
Messages: 412
Registered: July 2011
Senior Member
Messages here sit on the forum, and probably get emailed to participants in this thread, but not to everyone on the forum. You might want to post to the MIO List.
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