Cool Dude Ted

REW software

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1 hour ago, MartinC said:

For my check you didn't need to do anything with filters. Just directly compare the 5 measurements. It would have taken minutes. 

Can you post the SPL graph showing the 5 measurements with let's say 1/48 smoothing?

Will do.

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26 minutes ago, tuga said:

Hi Stuart,

I wouldn't use 1/6. Also, I would take care not to measure over an area wider than 30-40cm.

You can also try testing standing waves using these test tones or those found on youtube and your iPad's SPL meter.

Best,

Ricardo

Thanks for the reply. the 30-40cm area is related to the mic position?

Also 1/6 is too much smoothing?

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31 minutes ago, Cool Dude Ted said:

Thanks for the reply. the 30-40cm area is related to the mic position?

Also 1/6 is too much smoothing?

When performing MMM measurements I roughly move the mic inside an imaginary circle of around 30cm located where my head should be, and move it a bit front to back as well.

I think that for EQ'ing room response 1/6 is too much. I use 1/12, some people 1/24 even.

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1 hour ago, tuga said:

When performing MMM measurements I roughly move the mic inside an imaginary circle of around 30cm located where my head should be, and move it a bit front to back as well.

Have you ever tried using a larger volume? As you may know Dirac Live uses an average over multiple points for the basis of its filter design, but here the points are recommended to be at a minimum spaced over a sphere of 1 m diameter.

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@Cool Dude Ted I would though stop spending any time thinking about filter design or where you make measurements until you've actually been able to work out if you're getting meaningful measurements in the first place. 

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14 minutes ago, MartinC said:

Have you ever tried using a larger volume? As you may know Dirac Live uses an average over multiple points for the basis of its filter design, but here the points are recommended to be at a minimum spaced over a sphere of 1 m diameter.

I haven't. But moving that much forwards or backwards will make a massive change to the response and I am only correcting below 200Hz.

I made these many years ago, side walls are asymmetrical as can be seen by the difference in the measurements.

qdJbbDy.png

Edited by tuga

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9 minutes ago, tuga said:

I haven't. But moving that much forwards or backwards will make a massive change.

It does indeed. It may be the Dirac range is more important for full-frequency range corrections but it's something to consider trying. Note I've done lots of corrections using single point measurements too so I'm not a strong proponent of any particular approach but I think it's a variable worth exploring.

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42 minutes ago, MartinC said:

It does indeed. It may be the Dirac range is more important for full-frequency range corrections but it's something to consider trying. Note I've done lots of corrections using single point measurements too so I'm not a strong proponent of any particular approach but I think it's a variable worth exploring.

I would like to try Dirac or one of the more "evolved" response correction packages at some but I need to find out how to make them work with HQPlayer first.

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1 hour ago, MartinC said:

@Cool Dude Ted I would though stop spending any time thinking about filter design or where you make measurements until you've actually been able to work out if you're getting meaningful measurements in the first place. 

thank you. good advice. I will post the SPL graphs tomorrow but agree 100% that I somehow need to find out whether I can rely on the measurements being accurate. I’m concerned they may not be in which case my way forward would seem to be a USB mic which I am actively looking for. UMIK-1 seems to have a great deal going for it but none for sale 2nd hand that I can see. I think I need to bite the bullet, buy new and then sell on as I don’t plan on keep repeating this exercise.

Thanks.

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1 hour ago, Cool Dude Ted said:

thank you. good advice. I will post the SPL graphs tomorrow but agree 100% that I somehow need to find out whether I can rely on the measurements being accurate. I’m concerned they may not be in which case my way forward would seem to be a USB mic which I am actively looking for. UMIK-1 seems to have a great deal going for it but none for sale 2nd hand that I can see. I think I need to bite the bullet, buy new and then sell on as I don’t plan on keep repeating this exercise.

Second hand UMIK-1s tend to sell quickly, which on the plus side means if you buy one and decide you don't want to keep, you should be able to sell it on easily without losing too much money.

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4 hours ago, Cool Dude Ted said:

thank you. good advice. I will post the SPL graphs tomorrow but agree 100% that I somehow need to find out whether I can rely on the measurements being accurate. I’m concerned they may not be in which case my way forward would seem to be a USB mic which I am actively looking for. UMIK-1 seems to have a great deal going for it but none for sale 2nd hand that I can see. I think I need to bite the bullet, buy new and then sell on as I don’t plan on keep repeating this exercise.

Thanks.

Yes, using the right tools for the job is the way forward. Perhaps time to step back and have another look in a couple of days? A lot might become clearer then. As you will have gathered from us there is more than one methodology for arriving at a satisfactory result!

Blooming nuisance this covid; I see you’re in the next county so otherwise I could have popped over mic, stand and low tack masking tape in hand to give you a hand. Masking tape? if you pop some on the floor where the base of your mic stand is you can remeasure at the same spot.

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8 hours ago, Camverton said:

Yes, using the right tools for the job is the way forward. Perhaps time to step back and have another look in a couple of days? A lot might become clearer then. As you will have gathered from us there is more than one methodology for arriving at a satisfactory result!

Blooming nuisance this covid; I see you’re in the next county so otherwise I could have popped over mic, stand and low tack masking tape in hand to give you a hand. Masking tape? if you pop some on the floor where the base of your mic stand is you can remeasure at the same spot.

thanks for this. A very kind suggestion.

Please have a look at the comments which follow. They’re being “sent” to everyone who has been helping me with this thread. They’re both thanks and an apology. You’ll see what I mean when you read them!

Stuart

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@MartinC

@Camverton

@tuga

Hi to everyone who has been helping me on this thread trying to sort out my issues.

This morning, I have come across the box for my old analogue mic and it is with a mixture of acute embarrassment and apology that I have to admit that my mic has a frequency response of 100Hz - 16Khz; in other words pretty much every measurement taken so far is completely useless. And, it must go a long way to explaining why my bass booms at around 40Hz/80Hz have not been showing up in the graphs, despite me knowing about the standing waves present in the room.

What I do appreciate, though, is all the help that you have individually given me. It has not been wasted because even though the existing mic measurements are useless, you have all taken me through the basics and some complexities of using REW which I honestly believe leaves me in a very good place to proceed once I’ve purchased a “proper” USB mic.

In a recent post, MartinC suggested I stop worrying about filters until I worked out if my measurements were valid/accurate. I had always known that using the analogue mic was very much a trial for me using REW, but I had no idea then just how inaccurate my mic measurements were going to be.

As mentioned above , I am very embarrassed by this revelation and hope you will all accept my apologies. I’m sure that at some point in the future I will laugh about this - just not at the moment!

If it is not asking too much, I also hope you may be willing to re-engage with me on this subject (where you all clearly have invaluable experience), once I’ve sourced a mic (likely to be a UMIK and possibly imported).

Thank you all.

Stuart

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Don't feel embarrassed, and as you say you've learnt through the process so not a waste of time at all. I didn't know how well or badly your microphone might work either but it is why I was focusing on the raw measurements and variability you were seeing to try to assess this.

I believe from an avforums post that idealav have UMIK-1s in stock if you're interested. Other places may too of course.

Edited by MartinC

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