Measuring frequency response in living room

[Subbu68]

I am trying my hand building a OB with Ahuja 12FRX full range driver. I don't have any kind of measuring setup to check the FR of these speakers.

Would a SPL meter app on the phone and a tone generator programme on PC feeding the amp and speakers give a fair idea of the FR? Generate a tone of particular frequency, play through the speakers, measure the SPL in dBA on the phone, change the frequency of the tone, measure and so on. Record and plot on a semi-log sheet (maybe physical or on Excel Charts).

I am aware that the combined errors in the tone generator, phone's mic, measurement app etc. wouldn't give an accurate result compared to a dedicated measurement setup.

 

[amrutmhatre90]

Hi @Subbu68

Have seen your other thread, loved your tube amps.

I have tried small hands on the OB and boxed speakers, the mics in our phone are not that great to be honest.
Better look at mics which are specially calibrated, check out umik one its fairly cheap around 6-8k, connect them to the PC or laptop then feeding it to the amp. There are couple of tutorials on how to use UMIK to test the speaker drivers on Youtube.

One more thing I would like to ask, why are you going with the Ahuja 12FRX ? is it because you have it laying at home? or will you be purchasing it?

I have eyed one more such speaker from a different brand but slightly with better specs, I have had good experience with a woofer I had purchased from them, they are built good too. If you haven't bought Ahuja yet do consider these too.

Sweton Speakers - Order Online

 

[Subbu68]

Have seen your other thread, loved your tube amps.

I have tried small hands on the OB and boxed speakers, the mics in our phone are not that great to be honest.
Better look at mics which are specially calibrated, check out umik one its fairly cheap around 6-8k, connect them to the PC or laptop then feeding it to the amp. There are couple of tutorials on how to use UMIK to test the speaker drivers on Youtube.

One more thing I would like to ask, why are you going with the Ahuja 12FRX ? is it because you have it laying at home? or will you be purchasing it?

I have eyed one more such speaker from a different brand but slightly with better specs, I have had good experience with a woofer I had purchased from them, they are built good too. If you haven't bought Ahuja yet do consider these too.

Sweton Speakers - Order Online

Hi Amrut

thank you for the reply.

I live in UAE. Checked UMIK on Amazon.ae. Oh my!!, it is nearly INR 15,000.00!! Since it is not going to be a routine affair measuring SPLs, I have to be content with approximate measurement than spending on UMIK.

Now for the driver, I got Ahuja 12FRX already. That and Eminence are the only ones available here in UAE. Others have to be imported - a hassle. the link below explains the concept of choosing a driver for OB.

Designing Loudspeakers - Part 15 Open Baffles and Bass

From Hi-Fi World - February 2008 issue) Designing Loudspeakers Part 15 – Open Baffles and Bass When you think

www.hi-fiworld.co.uk

Sweton has low Qts of 0.38 and seems suitable for a sealed box. Ahuja has a Qts of 0.7 nearly satisfying the criterion. Eminence Alpha 15A was best suited for OB with high Qts but is quite large and needs space as well as with upper cut off at 4.3kHZ a tweeter is necessary that I wanted to avoid. Ahuja reaches 16kHZ and even a bit low is fine for my aging ears as well as super sensitive ears of my daughter.

Wanted to experience the coherence of FR speaker with whizzer cone. In fact I was planning to shed all the drivers from my Klipsch Heresy III, plug the openings of mid-range and tweeter and fit in Ahuja. The dimensions of HIII woofer (seems Eminence) is pretty much same that I can fit Ahuja in that cab. But then, it is a thing of beauty that I did not feel like cannibalizing it.

Heresy is very good with the valve amp but with certain singers (Vani Jayaram for example) it becomes a bit too sharp even with valve amp. Vani Jayaram's album Meera seems a good candidate to test sibilance of speakers . Many a times my daughter complains of ear ache when I play music. With the Ahuja's on a cardboard (now nearly 90cm x 90cm) and not broken in yet, still can compete with Heresy and seems smoother. Imaging is wonderful and my KEF Kube 12b sub is helping the bottom end well. Had to push up the cut off frequency and lower the volume a bit compared to Heresy.

 

[Enkay78]

Hi Amrut

thank you for the reply.

I live in UAE. Checked UMIK on Amazon.ae. Oh my!!, it is nearly INR 15,000.00!! Since it is not going to be a routine affair measuring SPLs, I have to be content with approximate measurement than spending on UMIK.

Now for the driver, I got Ahuja 12FRX already. That and Eminence are the only ones available here in UAE. Others have to be imported - a hassle. the link below explains the concept of choosing a driver for OB.

Designing Loudspeakers - Part 15 Open Baffles and Bass

From Hi-Fi World - February 2008 issue) Designing Loudspeakers Part 15 – Open Baffles and Bass When you think

www.hi-fiworld.co.uk

Sweton has low Qts of 0.38 and seems suitable for a sealed box. Ahuja has a Qts of 0.7 nearly satisfying the criterion. Eminence Alpha 15A was best suited for OB with high Qts but is quite large and needs space as well as with upper cut off at 4.3kHZ a tweeter is necessary that I wanted to avoid. Ahuja reaches 16kHZ and even a bit low is fine for my aging ears as well as super sensitive ears of my daughter.

Wanted to experience the coherence of FR speaker with whizzer cone. In fact I was planning to shed all the drivers from my Klipsch Heresy III, plug the openings of mid-range and tweeter and fit in Ahuja. The dimensions of HIII woofer (seems Eminence) is pretty much same that I can fit Ahuja in that cab. But then, it is a thing of beauty that I did not feel like cannibalizing it.

Heresy is very good with the valve amp but with certain singers (Vani Jayaram for example) it becomes a bit too sharp even with valve amp. Vani Jayaram's album Meera seems a good candidate to test sibilance of speakers . Many a times my daughter complains of ear ache when I play music. With the Ahuja's on a cardboard (now nearly 90cm x 90cm) and not broken in yet, still can compete with Heresy and seems smoother. Imaging is wonderful and my KEF Kube 12b sub is helping the bottom end well. Had to push up the cut off frequency and lower the volume a bit compared to Heresy.

miniDSP UMIK-1 - Home

USB calibrated measurement microphone for a plug 'n play measurement of your system. IN STOCK

shop.avenuesound.in

If you buy from avenuesound it’s 9k. I got umik 1 at 8k last last year

 

[Subbu68]

miniDSP UMIK-1 - Home

USB calibrated measurement microphone for a plug 'n play measurement of your system. IN STOCK

shop.avenuesound.in

If you buy from avenuesound it’s 9k. I got umik 1 at 8k last last year

Hi

Unfortunately, I can't get them to UAE from India. Courier charges, VAT, Import duty etc.

 

[sud98]

Why dont you look at buying minidsp from hongkong directly and get it shipped at UAE?

 

[arj]

Hi Amrut

'''

Heresy is very good with the valve amp but with certain singers (Vani Jayaram for example) it becomes a bit too sharp even with valve amp. Vani Jayaram's album Meera seems a good candidate to test sibilance of speakers . Many a times my daughter complains of ear ache when I play music. With the Ahuja's on a cardboard (now nearly 90cm x 90cm) and not broken in yet, still can compete with Heresy and seems smoother. Imaging is wonderful and my KEF Kube 12b sub is helping the bottom end well. Had to push up the cut off frequency and lower the volume a bit compared to Heresy.

An old trick with Klipsch horns is to put a small piece is tissue paper ( usual paper towel) in the horn..it slightly mellows it down.

Also try not to toe it and let it fire straight.

 

[Subbu68]

An old trick with Klipsch horns is to put a small piece is tissue paper ( usual paper towel) in the horn..it slightly mellows it down.

Also try not to toe it and let it fire straight.

I did try the tissue trick. Stuck it inside the grille to block the middle of the horn. Without toe-in it looses some of the imaging. In fact Paul Klipsch has written a paper and he says to toe-in nearly 45 degree!! Tried it - L pointing to right end of the sofa and R pointing to left end. That gives a surreal effect. It's like sitting in a concert hall. You move to the left, you can feel artiste on your left on the stage closer and those on right a bit far from you!!

The trial OB with Ahujas on a nearly 100cm square cardboard baffle is running close to HIII. Ahujas are nearly at the base and I have raised it on the stool that my HIII used to sit. Imaging is superb. I am getting addicted to that open sound.

 

[Subbu68]

Why dont you look at buying minidsp from hongkong directly and get it shipped at UAE?

How would I use it in my setup? A stereo valve amp 8Wpc. Never used any tone controls or Eq in my set-up. In my old Yamaha amp too it used to run in Pure Direct mode.

 

[IndianEars]

I am trying my hand building a OB with Ahuja 12FRX full range driver. I don't have any kind of measuring setup to check the FR of these speakers.

Would a SPL meter app on the phone and a tone generator programme on PC feeding the amp and speakers give a fair idea of the FR? Generate a tone of particular frequency, play through the speakers, measure the SPL in dBA on the phone, change the frequency of the tone, measure and so on. Record and plot on a semi-log sheet (maybe physical or on Excel Charts).

I am aware that the combined errors in the tone generator, phone's mic, measurement app etc. wouldn't give an accurate result compared to a dedicated measurement setup.

The Elephant in the room.... Is the room itself.

The room creates dips n spikes in the frequency response of 20 dB peak-to-peak or more... especially in the bass & mid bass freq range.

 

[arj]

I did try the tissue trick. Stuck it inside the grille to block the middle of the horn. Without toe-in it looses some of the imaging. In fact Paul Klipsch has written a paper and he says to toe-in nearly 45 degree!! Tried it - L pointing to right end of the sofa and R pointing to left end. That gives a surreal effect. It's like sitting in a concert hall. You move to the left, you can feel artiste on your left on the stage closer and those on right a bit far from you!!

The trial OB with Ahujas on a nearly 100cm square cardboard baffle is running close to HIII. Ahujas are nearly at the base and I have raised it on the stool that my HIII used to sit. Imaging is superb. I am getting addicted to that open sound.

Yeah many of the older speakers were suggested like that eg the older tannoys too ie extreme toe in. In the end it's a compromise between the Soundstage and the tone.

Most of this high freq is in the 2khz range and that's very directional hence any sort of absorption before it reaches the ear is perhaps your only option

Completely agree and get your point around keeping the signal free from any dsp in the chain.

 

[Bloom@83]

How would I use it in my setup? A stereo valve amp 8Wpc. Never used any tone controls or Eq in my set-up. In my old Yamaha amp too it used to run in Pure Direct mode.

+1
Never liked tone controls at any point in my chain.

 

[Subbu68]

The Elephant in the room.... Is the room itself.

The room creates dips n spikes in the frequency response of 20 dB peak-to-peak or more... especially in the bass & mid bass freq range.

Yes, experienced it yesterday.

With Keuwlsoft SL App on my Droid tried measuring from 30Hz in steps of 10Hz. Base noise was around 51 dBA. The phone was on a tripod at my listening position and low volume on PC 20%, DAC in full, Amp nearly 75%.

No response till 60Hz (57dBA) then a jump to 62dBA @ 70Hz. Was happy Wow!! good response - then 72 dBA @ 110Hz.. even better Wow!! then a slump to 60 dBA @ 120Hz, up 69dBA @140Hz, then sedate 58 - 60 dBA till 260Hz and a jump to 76dBA @280Hz, then back to 60dBA at 300Hz. Stopped at that.

It's a rented apartment so cannot tinker much with the room. Due WAF cannot change the furniture positions much or even add a carpet as it collects dust (due to the atmospheric dust here in UAE - some gets pumped in through a/c fresh air input, some from window when we open).

 

[IndianEars]

Here is a typical Room Frequency Response.

Website



Imagine measuring your DIY Open Baffle Speaker in a Room.... and inferring that this is your Speaker's Frequency Response

 

[Subbu68]

Here is a typical Room Frequency Response.

View attachment 68071Website



Imagine measuring your DIY Open Baffle Speaker in a Room.... and inferring that this is your Speaker's Frequency Response

Thanks for the graph and website link.. That seems to explain my observation. Nearly the same. Would read through after work today.

 

[arj]

Here is a typical Room Frequency Response.

View attachment 68071Website



Imagine measuring your DIY Open Baffle Speaker in a Room.... and inferring that this is your Speaker's Frequency Response

Thanks @IndianEars . I was told that the typical hump at the 50-60hz is also due to the ceiling ie most houses have it between 9-10 feet and this is something you cannot really avoid much.

 

[alpha1]

1) Use room EQ wizard (windows based program) - very convenient and you can do sine wave sweep test (that shows you impulse response, waterfall etc) as well as pink noise response (average frequency response)
2) Use any good quality microphone that is used for music - some websites/technical literature plot their frequency response. Choose the ones that are flatter. Calibrated mics are too expensive - and perhaps not warranted.

 

[IndianEars]

Thanks, Alpha1. Good pointer......

but kinda Chicken n egg situation....

the thread title is "Measuring freq response in a living room" ( for DIY Open Baffle Speakers).

​

 

[mbhangui]

2) Use any good quality microphone that is used for music - some websites/technical literature plot their frequency response. Choose the ones that are flatter. Calibrated mics are too expensive - and perhaps not warranted.

I have this Yeti Blue microphone and mxl 770 condenser cardoid microphone. Can I use them? Alternatively can you suggest a microphone that I can get from amazon.in?