How do you check , how Low your speakers dig ?

quadklipsh

Super Member
Hi guys , would it be fine if i ask this question here .

I am using a pair of speakers that i custom built 2 yrs ago .
I wanted to know how it did so well in the bass department because i sold my floor standers klipsch RF3s afterwards .

Is there a reasonable and free of cost way (well you know a casual way ) of getting an idea of the low end frequency output where the speaker is still considerably audible ,like 30 hz or 25 hz @90dB or so ????
The speaker drivers are :

8" AUDAX HM210ZO
AC1 HAT MKII tweeter...

With a Linkwitz Riley 2nd degree Crossover ...
In a cabinet of 24"H x 10"W x 22"D dimensions .
 
I got a $5 app for my iPhone (and ipad) called Octave RTA - I put the iPad in a camera tripod mount, put on a CD with Pink noise (wide-band test-signal) and had a look. Not bad for a $5 app, hey?
I mean, a good RTA uses a calibrated microphone and much more expensive sources, but this is fine for a quick and dirty look ...
of course, presuming you already have an iPhone or iPad ...

ALTEC-RTA.jpg




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well well well......
I was thinking if i could run a youtube clip with a tone sweep from 20 to 20000 hz .Place a cellphone mic up front and note the decibel levels using an App.
the peaks and troughs may give an idea
 
The iPhone RTA is a good quick check as long as you don't need calibrated levels; it will certainly get the frequencies right. There's also a free app called REW (Room EQ Wizard) which has, among its many features, a good RTA with selectable bandwidth. It will work with many calibrated mics, or you can calibrate your own using a known source.
 
+1 on the REW, but there is SOME money to be spent. Software is free, and if you've already got a laptop, all you really need is a calibrated mike. If you've an older laptop, you'd probably also want to invest in an ADC as on board sound handling was pretty bad a few years back. My 10 year old Toshiba paired up well with a $20 Behringer UCA202.

Fire up REW, set the SPL levels to match your system (all in the instructions), and run a few frequency sweeps. Average the results and know exactly what your hearing.

Once you've got the equipment, DO take a look at the results across the band and consider implementing a DSP EQ solution on your room. Night and day difference. I already have jRiver Media Center as a server front end on my HTPC and used their "convolution kernel" ... REW can output it's results to the software with studio quality results.

PS - I was pleasantly surprised when I was able to get usable SPLs at 14hz here on my newly refurbished McIntosh speakers. You can't hear anything that low, but you can sure as hell feel it!
 
A DDD 1812 overture CD played, will quickly let you know how well your bottom is producing before it rips your woofers out of the speaker frames/baskets/spider if you have the SPL up too high !!
The CD I own warns the user of potential low frequency damaging energy if not handled carefully..
 
Yes, Audacity is very good for this and free as well. Although it's not accurate with frequency below 30 hz as you'll likely just get a low chopping sound as opposed to a controlled tone. And even if your speakers can't get below 30 hz, they'll likely respond to Audacity at these levels.
 
Actually, all the above must take the acoustics of the room into consideration and you can't get an accurate representation of what the speaker is really doing.

To do this outside of an anechoic chamber/open environment, it is best to place the microphone <1/2" from the woofer's cone AND do it for the port area and sum them according to size. While easy with a true mic, this could be difficult if trying to use a cell phone.
 
A DDD 1812 overture CD played, will quickly let you know how well your bottom is producing before it rips your woofers out of the speaker frames/baskets/spider if you have the SPL up too high !!
The CD I own warns the user of potential low frequency damaging energy if not handled carefully..

I'll have to use that to test the protection circuits on my big box McIntosh ... <G>

994976-mcintosh-xr16-isoplanar-speakers.jpg


Those also have LEDs on the front that will flash as the speakers approach saturation. It's fun watching those glow when listening to Porcupine Tree's Russia on Ice ... that hits them with pure sine at incredible SPLs ...

Actually, all the above must take the acoustics of the room into consideration and you can't get an accurate representation of what the speaker is really doing.

To do this outside of an anechoic chamber/open environment, it is best to place the microphone <1/2" from the woofer's cone AND do it for the port area and sum them according to size. While easy with a true mic, this could be difficult if trying to use a cell phone.

This only gives you one set of numbers that may at least eliminate the speakers as a problem if your environmental tests fail to give the desired results. One should still plan to test at the primary seating position(s) to get an overall picture of how you're doing. The inter-relatedness of all things, eh. Ohmmmmmmmmm ...
 
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I'll have to use that to test the protection circuits on my big box McIntosh ... <G>

994976-mcintosh-xr16-isoplanar-speakers.jpg


Those also have LEDs on the front that will flash as the speakers approach saturation. It's fun watching those glow when listening to Porcupine Tree's Russia on Ice ... that hits them with pure sine at incredible SPLs ...



This only gives you one set of numbers that may at least eliminate the speakers as a problem if your environmental tests fail to give the desired results. One should still plan to test at the primary seating position(s) to get an overall picture of how you're doing. The inter-relatedness of all things, eh. Ohmmmmmmmmm ...


YES, I agree.
Be careful Sir. As the DDD 1812 played at, what I thought was moderate, and also thought was realistic/natural SPL levels broke the glue bond of the spider and voice coil on the bottom one of two per cabinet 12" woofers on the right side of my Mac XRT-30 speaker system, which brought that listening session to a abrupt halt with the speaker was no longer wolfing, but barking instead with Mac 1201`s powered with 40 amps peak current @ 240 volts of available input power !!

I guess I slapped her a little too hard with that digitally recorded very, very LF high rise time, high power input un-restricted wave form..
That speaker really didn`t like me ripping her panties off and having my way with her !! HAHAHA !!
But those tail end cannons were in my face/living room before that speaker jumped off the preverbal cliff !!

Do be careful sKiZo, going there, if you so feel adventurous !!

Enjoy the music, as always..

Kind & respectful regards, OKB
 
Aw shucks ... bein' careful tain't no fun atall!! <G>

Thanx for the warning anyway.

Speaking of McIntosh - I can tell you I blew a LOT of speaker fuses with my 2205 solid state amp, even with the amp's vaunted protection circuits engaged. Haven't blown one since switching to a tube amp that puts out half the power at the same SPLs. Big difference I'd think would be "hard" vs "soft" clipping inherent in each design.
 
I have also used the Stereophile Test CD 3 with a digital spl meter.
BTW most spl meters are only accurate to 30hz.
 
Ok. And would someone mention how low you actually got and what are your speakers
I have an infinite baffle rig that goes down to 9 Hz, but the regular speakers that shocked me the most were ADS L1530s, which produce usable output down to 14Hz, which seems to defy the laws of physics.
 
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