Measuring Some Vintage Speakers

[RickS]

Sorry, a bit too much to consider here and am busy with winterizing. Did you try the REW support forum?

Official REW (Room EQ Wizard) Support Forum

Guides / Links / Notes / Setup / Connection / Testing Official Support Forum for Room EQ Wizard (REW) by John Mulcahy

www.avnirvana.com

 

[Vladimir Filevski]

Could that be caused by the drivers not really being time-aligned relative to the measuring microphone?

It might be. Try several mic positions up and down relative to tweeter.

 

[bconline]

Sorry, a bit too much to consider here and am busy with winterizing. Did you try the REW support forum?

Totally understandable. Thank you for your kind help up to this point. I'll try to figure this out on my own. Good luck with the winterizing!

 

[Zeltergiest]

The last two are Boston Acoustics VR-M50 and VR-M60. The difference is woofer size (5.25"/ 6.5") and cabinet size. Solid build.

View attachment 360244 View attachment 360249

Any possibility of me acquiring the measured files for the VR-M60? I'm working on a project with them currently but I don't have any way of measuring them currently. Any help is appreciated, thanks!

 

[bconline]

Any possibility of me acquiring the measured files for the VR-M60? I'm working on a project with them currently but I don't have any way of measuring them currently. Any help is appreciated, thanks!

Sure. Attached is a zip of the .mdat file for the VR-M60's. Hope this helps.

 

[bconline]

It might be. Try several mic positions up and down relative to tweeter.

At your suggestion, I measured at three positions - woofer level, tweeter level and slightly above the tweeter level. The step response was indeed different. If I am interpeting the graphs correctly, the measuring position above the tweeter level has good time alignment between the tweeter and woofer. If this is true, it would make sense because at normal seating position, ear-level is higher than tweeter level.

Step response measured at woofer level:

Step response measured at tweeter level:

Step response measured above tweeter level:

Here's the set-up, above tweeter level.

 

[bconline]

To check the measurements, I used the same set-up to measure a single-driver speaker and a standard 2-way bookshelf speaker. Hope I'm doing this right... or close to right.

Step response of a single-driver Alpair 10.2:

Step response of a Monitor Audio S2:

 

[Vladimir Filevski]

he measuring position above the tweeter level has good time alignment between the tweeter and woofer

OK. Now measure frequency response at that mic position. Is the measuring distance same as listening distance? If not, keep the same angle when measuring at the listening distance.

 

[bconline]

OK. Now measure frequency response at that mic position. Is the measuring distance same as listening distance? If not, keep the same angle when measuring at the listening distance.

Here's the corresponding frequence response graph. Distance is 1 meter.

 

[Vladimir Filevski]

Appears you don't have Baffle Step Compensation - everything above 500 Hz is elevated (also, tweeter output is too "hot").
Or, you have a room acoustic problem causing the dip between 150 Hz and 600 Hz.

 

[Zeltergiest]

Sure. Attached is a zip of the .mdat file for the VR-M60's. Hope this helps.

Thanks! What voltage did you measure them at? Long shot but any chance you’re able to measure the T/S parameters of the woofer and tweeter on the VRM-60? I don’t have a dats currently.

 

[gino1961]

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

Hi ! thank you very much for your great work and congratulations for your impressive collection
why did you choose 80dB level ? will the curves change at 90db ?
the FRs seem all within +/-5dB I would say that all should sound good ?
any differences in sound should be related to something else Who knows what

 

[BigVU's]

I really dig this post. Nice contribution. Provides some justification in my search of the thrifty vintage treasures that may be out there.

Bconline, I am interested if you set aside the measurements, and were just subjectively listening to your liking, which one would you choose at a garage sale?

 

[bconline]

Hi! Sorry for being absent for so long. Work and family matters have kept me away. I have continued to acquire and test vintage speakers and have about dozen measurements to post. But first to the open questions:

@Vladimir Filevski: I agree - that speaker sounds better with DSP to correct and tune.

@Zeltergiest: Sorry, don't have T/S parameters for the VRM-60 woofer. If I get a dats, I measure them if you still want to know.

@Zeltergiest and @gino1961: I wasn't rigorous about setting levels and don't know what voltage I used. It was a bit low because I was worried about damaging the speakers or bothering the neighbors. All the speakers sound "pretty good". But some definitely souded better than others. The audible differences were much more than the response charts show. I think, mostly because the directivity and the room interactions varried widely.

@BigVU's: You mean "which of my kids do I love the most?" To be truthful, I have two favorites.

The Sonus Faber Concertino's sound fabulous in my room and they image better than any speaker I've had. The measurements I posted above show a nice even dispersion pattern. I run them with two subwoofers, one near each speaker. If any of you have a chance to buy a pair for a reasonable price - go for it. You won't be sorry. Look for the original version with dual binding posts.

My other favorite is the Elipsa custom. It is the result of an extensive collaboration by the best of the DIY community. They image almost as well as the Concertino's, and can project a huge sense of scale with music like Chocolate Chip Trip and Hanz Zimmer.

 

[bconline]

Back to measuring vintage speakers...

I helped my neighbor sell 3 sets of Spendors that he had owned for over 40 years. They were in pristine condition. Of course, before sellling them, I had to measure them. Here are the BC III, B I, and SA 1 mini monitor (right to left):

 

[bconline]

First, the Spendor BC III (aka BC Three). 4-way with 12" woofer. Thin wall construction design. Picture from the internet because the grills were not removable. Remarkably well matched left and right.

 

[bconline]

Next, the Spendor BC I. 3-way with 8" bextrene woofer. Also thin wall construction design. Smooth response, and best sounding of the 3 Spendor models to me.

Here are a couple of pictures of the construction. 3/8" plywood walls. 1/2" plywood back, no bracing.

And speaking of measurements, I found this amusing, from the Stereophile review back in 1978. They publish a graph of how it "sounds... rather than how it measures". Huh???

 

[bconline]

The last of my neighbor's speakers, the Spendor SA1 mini monitor. 2-way sealed with 6" bextrene woofer. Sounds and measures really nice for a 50 year old speaker. There have been several interations of the SA1. This was the first.

 

[bconline]

And here's a bonus Spendor that I acquired recently, the Spendor S3/5. 2-way with 5" woofer. Meant to replicate the mystique of the BBC's famous LS3/5A.

 

[bconline]

One more vintage import for the night. The Linn Keilidh. A short MTM floor stander with 61/2" woofers. Sealed.