How to measure baffle step in my room?

[Jesse055]

I want to get into measuring to some extent and the first thing I would like to know is how much baffle step I have and what that curve really looks like in my room with my speaker placement. My speakers in my main listening room really have only one place to go and have to be 10 to at the most 16 inches from the wall. One speaker has to be in a corner, again 12 to 16 inches from that side wall. The room is open on the other side. I do have a 55 inch LCD tv between the two speakers. The gap between the speakers and the tv vertically is 8-10 inches. The room has carpet. So instead of simulating this I would just like to know the true baffle step and it's curve especially considering the use of a corner and if the tv is altering the baffle step frequencies(boosting them)

I have done a lot of reading on this forum and the internet about measuring. Most of it is about impulse measuring with a short gate window, sometimes outside. Because my speakers are going to such a known space, I don't think making measurements that exclude my room and fixtures is what I need besides the short gating would not allow the bass data to be valid.

Given my room and what I want to learn and find out, how would you recommend I measure? What technique or method?

I'm thinking a non gated impulse or a longer gate that allows reflections? Or would a simple pink noise and RTA capture this? This is why I need guidance from you experienced in this. Currently I do have a cheap imm6 calibrated mic and audiotools by studio six on my iPad and I could add LARSA or room impulse response. So if I could get by with this as the more I read the more confused I become about what measurement software I will decide on in the near future.

[Sydney]

Re: How to measure baffle step in my room?

...how much baffle step I have ...

Well how big is your baffle :p

[Jesse055]

Re: How to measure baffle step in my room?

Well how big is your baffle :p

This particular baffle is 11.5 inches wide by 23 inches tall. And 12 inches deep. The woofer is at the bottoms 5 inches from the bottom but I am planning to have this on a base so in the end the baffle will be same as 40 inches long.

[Sydney]

Re: How to measure baffle step in my room?

If not mistaken, Jeff B has a simulator that can predict the behaviour of the baffle itself.
I'm guessing however that you want to measure the interaction with the room acoustics?

[Jesse055]

Re: How to measure baffle step in my room?

I'f not mistaken Jeff B has a simulator that can predict the behaviour of the baffle itself. I'm guessing that you want to measure the interaction with the room acoustics?

Yes and eventually I plan to try it and use it not only for learning but design. Also I do not have ms excel. But right now I want to learn measuring so I wanted a method to measure. So much of what I read is about measuring to ignore the room. What I need help with is how to measure it. Advice?

[Sydney]

Re: How to measure baffle step in my room?

Have you looked at REW ( Room EQ Wizard )?
http://www.roomeqwizard.com/

[Jesse055]

Re: How to measure baffle step in my room?

Have you looked at REW ( Room EQ Wizard )?
http://www.roomeqwizard.com/

Yes I've read about rew. I guess my basic question is what type of measurement I need and the methodology of the measurement to measure my speakers and my room combined.. Once I know that then I can decide whether it's omniscient or rew or arta?

[Jesse055]

Re: How to measure baffle step in my room?

I want to get into measuring to some extent and the first thing I would like to know is how much baffle step I have and what that curve really looks like in my room with my speaker placement. My speakers in my main listening room really have only one place to go and have to be 10 to at the most 16 inches from the wall. One speaker has to be in a corner, again 12 to 16 inches from that side wall. The room is open on the other side. I do have a 55 inch LCD tv between the two speakers. The gap between the speakers and the tv vertically is 8-10 inches. The room has carpet. So instead of simulating this I would just like to know the true baffle step and it's curve especially considering the use of a corner and if the tv is altering the baffle step frequencies(boosting them)

I have done a lot of reading on this forum and the internet about measuring. Most of it is about impulse measuring with a short gate window, sometimes outside. Because my speakers are going to such a known space, I don't think making measurements that exclude my room and fixtures is what I need besides the short gating would not allow the bass data to be valid.

Given my room and what I want to learn and find out, how would you recommend I measure? What technique or method?

I'm thinking a non gated impulse or a longer gate that allows reflections? Or would a simple pink noise and RTA capture this? This is why I need guidance from you experienced in this. Currently I do have a cheap imm6 calibrated mic and audiotools by studio six on my iPad and I could add LARSA or room impulse response. So if I could get by with this as the more I read the more confused I become about what measurement software I will decide on in the near future.

Some speakers are full 6 db and others are partial.......I'd like to know for sure the amount of BSC I need in my specific application and what measurement methodology will give me a pretty good measurement. I see so much posting that tries to. Filter out the room. Thing is I don't plan on listening to music in my back yard or an anechoic chamber. Someone steer me in the right direction. At least give me something to get me decent results. I'm a total noob on measurement. I think I've read just enough to confuse myself.

[Sydney]

Re: How to measure baffle step in my room?

Some speakers are full 6 db and others are partial.......I'd like to know for sure the amount of BSC I need in my specific application and what measurement methodology will give me a pretty good measurement. I see so much posting that tries to. Filter out the room. Thing is I don't plan on listening to music in my back yard or an anechoic chamber. Someone steer me in the right direction. At least give me something to get me decent results. I'm a total noob on measurement. I think I've read just enough to confuse myself.

Consider that this might be part of personal voicing.
You probably read where Jeff B. mentioned that the baffle transition on a rectangular baffle results in ripples.
This was demonstrated by Harry Olson long ago.

[Jesse055]

Re: How to measure baffle step in my room?

Consider that this might be part of personal voicing.
You probably read where Jeff B. mentioned that the baffle transition on a rectangular baffle results in ripples.
This was demonstrated by Harry Olson long ago.

Yea I'm sure there will be lots of peaks and valleys but I need to measure it, It's still my hunch that the overall baffle step will show up in spite of the other effects.

[Wolf]

Re: How to measure baffle step in my room?

If you measure the drivers in your cabinet with a gated impulse that removes the first reflections, the baffle step affect will be the droop in the lowend in the measurements, as well as maybe a peak around the wavelength of the width of the baffle, and some minor ripples above there related to piston diameter.

The droop in the measurements and how many dB is required to flatten out the curve in the xover (BSC) from this droop is known to be an average of 6dB. If room response factors into the mix, it can be less, but rarely should it be less than 3dB, and 4-6dB is most common. However, this can vary due to personal taste and voicing.

Later,
Wolf

[jonpike]

Re: How to measure baffle step in my room?

Some speakers are full 6 db and others are partial.......I'd like to know for sure the amount of BSC I need in my specific application and what measurement methodology will give me a pretty good measurement. I see so much posting that tries to. Filter out the room. Thing is I don't plan on listening to music in my back yard or an anechoic chamber..

You want to filter out the room when you're designing the crossover to eliminate that which isn't the drivers and the baffle, especially around the crossover frequency. What you're eliminating with the windowing is not "filtering out the room" as much as it is cutting out the echoes that add false information to the frequency response.

Well... there are several things adding together in the final speaker/room system. Way complicated to try and fully Sim all of that the same time. So, general practice is to get response of the baffle and speaker, since that's not hard to Sim and measure. Make a flat speaker, and at least you get just the room/placement effects, not room + speaker + bias in the response. Makes for a more universal speaker. Placement, room treatment, EQ, can address excessive room effects.

OTOH, being relatively near the back wall, plus being very close to a large plane (the TV) will add some bass reinforcement and alter the baffle step effect. So, if you always want to use them there, you might want to compensate for it.

There are a few baffle simulators out there, and there is Jeff's that includes some room boundary effect simulation , that will show you something about the placement effects. But, I don't know of a simulator that will easily show you the effect of a nearby TV. I'd guess you could wing it by doing the actual baffle, and also doing a much larger one like the baffle plus the TV area. Reality would be somewhere between. Anyone do this and measure after?

Luckily, as our ability to accurately measure lower frequencies goes down, the need for accuracy goes down somewhat as well. You want to carefully measure or simulate the higher frequency effects of baffle diffraction and include that in the crossover, while dealing with the lower BSC effects are more abut setting the bass balance in the low end, and that becomes a simpler slope effect. Mostly... Having a crossover where you can easily change that would make it easy to experiment, not always possible. A bit of EQ might help in the final adjustment, as well.

Jeff and Charlie's work on LF determination would be a good way to go for a method to get good LF design info to base everything else on.

Hope that helps...

[Jesse055]

Re: How to measure baffle step in my room?

If you measure the drivers in your cabinet with a gated impulse that removes the first reflections, the baffle step affect will be the droop in the lowend in the measurements, as well as maybe a peak around the wavelength of the width of the baffle, and some minor ripples above there related to piston diameter.

The droop in the measurements and how many dB is required to flatten out the curve in the xover (BSC) from this droop is known to be an average of 6dB. If room response factors into the mix, it can be less, but rarely should it be less than 3dB, and 4-6dB is most common. However, this can vary due to personal taste and voicing.

Later,
Wolf




Ok so do I really want to exclude the first reflections aren't they part of the frequencies that lessen the baffle loss? for instance the reflection off my 55" tv or the corner wall(acting partially like a larger baffle),would that be included in the gated measurement or not? Because it's my understanding those would or could partially reflect the longer wavelengths back to the listening position, thus lessening the actual baffle diffraction loss. I guess I'm stuck on reflection terminology as I thought the entire baffle issue is about reflected energy 2pi, or no reflection but wrap around into 4 pi? So is the gated still capturing those reflections off the baffle.? If so then I guess it's the term reflections and which reflections are excluded? Hope I am explaining myself well.

[Jesse055]

Re: How to measure baffle step in my room?

Jonpike,

Ok so I think you are getting the point I'm having trouble with.....the later reflections vs the reflections that are close in time with the reflections off the baffle itself. So the gating I thought even excluded the reflection off the floor. I guess I need to better understand what reflections are included in the gate? So gating allows the first reflection off the baffle that remains in 2 pi to still be captured?

[Jesse055]

Re: How to measure baffle step in my room?

Well... there are several things adding together in the final speaker/room system. Way complicated to try and fully Sim all of that the same time. So, general practice is to get response of the baffle and speaker, since that's not hard to Sim and measure. Make a flat speaker, and at least you get just the room/placement effects, not room + speaker + bias in the response. Makes for a more universal speaker. Placement, room treatment, EQ, can address excessive room effects.

OTOH, being relatively near the back wall, plus being very close to a large plane (the TV) will add some bass reinforcement and alter the baffle step effect. So, if you always want to use them there, you might want to compensate for it.

Yes jonpike, for now I'm designing for that room and I'm not interested in how universal. It is. I don't want to filter out the room or the tv. Like you said a simulator can't really mimic my room and that tv and my coffee table , Ect. I want e type of measurement that shows me is the true baffle step in my room 2 db? 4db, 6db, then that will be part of the crossover design. As well as the slope and other characteristics of the response.