Measuring Some Vintage Speakers

[bconline]

Here are modern v.s. vintage stand mount's. Infinity IL10 in Brown versus Focal 806V in Green. Remarkably similar for being 20 years apart.

 

[bconline]

First, you want the tweeter height to stay fixed at about half the ceiling height. Otherwise, your floor bounce is changing with each speaker you measure. Also, this makes for easier, more consistent measurements between speaker sweeps. From your mdats, your gate should be set to 10-11 msec. It appears you should invert the signal too.

If you do not have a SPL meter to set a level, you should set a level that is fairly high (by ear). If you do not or environment noise is high, you will not get above the noise floor and some measurements will be unreliable (as per the distortion discussion with @Juhazi). Once you find a reasonable level, should keep it the same for each speaker or cannot even do relative SPL comparisons between the speakers.

Your supplied mdats are showing 1/12 smoothing, 1/6 is a bit much. If you do the gating, should be able to do without additional smoothing, but otherwise 1/12 or 1/24 is preferred.

Did you calibrate your soundcard? If not, your measurements will be less accurate (but still can be relatively compared).

Hope this helps! Hope this does not dampen your fun too much, my wife is the fun one in our family. 

Thanks! I really appreciate the suggestions. I'm thinking I may do this outdoors next time. It's all fun for me!

 

[Juhazi]

Some users were worried about loosing high freq accuracy with long gating. This will not happen noticably!

Here animation of my indoor small room responses of same 0-15deg off-axis measurements. Same data but different fixed gating, same right window type.

And distortion of same on-axis measurement. Speaker spl was too low for distortion to show up above noise level

 

[Rja4000]

I'm not sure how to interpret this, but here's the RMS average of the 14 measurements. Does this confirm room modes you mention?

View attachment 360415

To make sure, you'd want to add the spread..
If you see little spread for a strong dip or peak, that is a strong indicator of room-related issue.

 

[totti1965]

I thought this group would be interested in how some vintage speakers compare to each other under the same measuring conditions. I have a collection of vintage speakers and simple measuring setup. No Klippel machine for me! I measured the frequency response of each speaker with:

• Laptop PC with Creative soundcard
• REW software
• Dayton UMM-6 microphone, with calibration loaded in REW
• Random Denon amplifier
• 1 meter distance, on the tweeter axis
• 20x24 garage with hard floor and 9.5' ceiling
• Small amount of damping on the floor

All of the measurement suffer from a floor bounce dip at ~80-90hz depending on the height of the woofer and mic. Sorry about that.

Here's the setup.
View attachment 360204

Here's the collection.
View attachment 360206

Here's all the graphs together. I'll post each frequency response curve separately.
View attachment 360208

Okay, give me the Revel!

 

[BDWoody]

Thanks! I really appreciate the suggestions. I'm thinking I may do this outdoors next time. It's all fun for me!

I learned a TON from just buying a little audio analyzer and measuring a bunch of stuff around the house. I can imagine going through this, along with the feedback has been a great learning experience.

I very much appreciate you sharing all of this with us, and we can learn along with you.

 

[Mosquito]

Back to a custom speaker with a Focal 6" kevlar woofer and 1" inverted kevlar dome tweeter. Time aligned baffle with removable outer frame.

View attachment 360220 View attachment 360219 View attachment 360221

IMHO the most interesting speaker of the bunch

 

[Short38]

This is a wonderful post, thank you for your generous contribution.

I’d be fine with nearly all of these and really like the home brewed speakers. Think I’ll pull out some retired drivers and a signal processor and go to work!

 

[OldHvyMec]

Here's a comparison of the two.

This is one of the thing I make SURE is the same between speakers. Sub/Bass not so much but mids and highs YES.
SPL matched as close as you can get it. You would be surprised how many pairs of speakers are WAY off comparing
one to the other. I had/have Strathearn, and Monsoon drivers that you have to match left and right drivers and then
match SPL (or in a Strathearn restring a new ribbon) by adding the correct resistor on the higher SPL. .5% is the goal
for me. That is the only reason I add L-Pads. For my ears and artifacts in the room.

First limiting tone controls, then removing most of them with AVR/AVPs and then removing L-Pads. It was a dog
gone conspiracy. Thank God for Yamaha and Mcintosh.

Regards

 

[mhardy6647]

OK – if that’s really what you’re after, then you could as well sit on your couch and watch the whole procession from there

Or, in some locales, perhaps a Chesterfield, davenport, or divan.

 

[audiotron]

That is a cool collection and thanks for the data.

 

[Postlan]

In terms of frequency response alone, speaker design was almost perfected 50 years ago.

 

[LugsyTL47]

In terms of frequency response alone, speaker design was almost perfected 50 years ago.

As well as physical design with personality.

 

[OldHvyMec]

Right, because sound is like a laser beam. Goes straight and does not deviate. Walls? Whatever.

Close, I've never heard a curve yet. Maybe a sinker sound or better it only fits in one ear and not the other. Sound travels as straight as an arrow
unless I missed something. It hits an object and a portion of the sound wave is deflected, absorbed, defused and from there every boundy has a
diminishing effect called decay. Quite measurable at a rate of X over the number of feet.

Room excitement/loading is a result of one thing the amount and type of room treatment used.

You can kill a majority of all sound outside that 15 degree off axis measurement with little effort. Below 80hz is a different story, it starts out
with such long waves it becomes omni directional because of the rooms boundaries. On an IB or an open location you can locate the direction
of sound below 80hz pretty easy. In a room not so much with very little effort from the person that set it up.

The importance of treatment at points of first reflection, diffusion, absorption, and cancelation (Helmholtz, combing and suck out) is not a
DSP thing with 2 channel at all. You would think DSP was a miracle. It's a program and some code is a lot different compared to a different
programmers code. Not all DSP is equal and in my case, not needed at all from 300hz and >. PEQ and Helmholtz pretty well take care of any
sub/bass issues.

Regards

 

[DanielT]

Bconline, if you feel up to it, I'd be curious to see the results anyway, so turn Mark Audio Alpair 10.2 upside down so the driver ends up close to the floor.
Then tilt it up just enough and take a measurement. Would be fun to compare that result with your original measurement.

It can be varied, up and down wedged in a corner, for example.It should be able to give 6 dB boost. It's good because you're tinkering with EQ, since you
you have dB to use and even then lower the distortion when the drivers due to the acoustic boost do not have to work so hard. It might be so, I should add. Besides, it's not certain that you like the sound character it gives in terms of reflections, .or you like it. I obviously don't know what you like.
There's a lot you can try, because it's fun.

Speaking of reducing the first floor reflex, Snell I was designed with that in mind:



The best and most extreme solution to reduce floor and ceiling reflections is line speakers that go from floor to ceiling. For aesthetic reasons maybe not so many people's cup of tea plus they require a lot of EQ, which not everyone wants to tinker with.

 

[Hipocrates]

Great and fun thread @bconline, Is highly appreciated!

 

[welwynnick]

Sound travels as straight as an arrow unless I missed something. It hits an object and a portion of the sound wave is deflected, absorbed, defused and from there every boundy has a
diminishing effect called decay.

I'm kind of at the same place as you with respect to sweet spot and room correction. But for the record, while sound does generally travel in straight lines, like all other waves, it also exhibits refraction and diffraction, meaning that those straight lines do get bent sometimes.

 

[DanielT]

I'm kind of at the same place as you with respect to sweet spot and room correction. But for the record, while sound does generally travel in straight lines, like all other waves, it also exhibits refraction and diffraction, meaning that those straight lines do get bent sometimes.

Just keep this in mind:

Speaking of dispersion, it is addressed in this thread:

Select dispersion pattern

Which dispersion pattern had you chosen? If we play with the idea that you would use a waveguide. Choose vertical and horizontal dispersion and feel free to justify your choice. For inspiration here you can see different waveguides...

audiosciencereview.com

 

[B.A.T.]

Great work, thank you!

 

[welwynnick]

Just keep this in mind:
Speaking of dispersion, it is addressed in this thread:

Select dispersion pattern

Which dispersion pattern had you chosen? If we play with the idea that you would use a waveguide. Choose vertical and horizontal dispersion and feel free to justify your choice. For inspiration here you can see different waveguides...

audiosciencereview.com

That's just directivity, not dispersion or other beam-bending phenomena. Dispersion has different meanings, but in the context of wave propagation it's where group velocity is a function of frequency, and gives rise to refraction. However HiFi folk seem to have adopted it to mean directivity, which I don't think OldHvyMec was really talking about.