A Subjective Blind Comparison of 3in to 5in Full Range Drivers

[perceval]

Looking forward to round 2!

 

[xrk971]

Breaking in A7.3

The A7.3 has arrived and has been installed in the test system for break-in as recommended by the manufacturer. I took some data before the break-in to compare with after break in to see if there is a measurable difference. Playing Norah Jones over and over at low volume (full range, no XO) for now...

Btw, this is the only driver that I am putting through time-consuming break-in period.

 

[bval]

I'd like to thank you for your efforts in providing objective data despite what seems like constant criticism directed towards you throughout this thread and the other thread you created.

I look forward to the second round!

 

[xrk971]

I'd like to thank you for your efforts in providing objective data despite what seems like constant criticism directed towards you throughout this thread and the other thread you created.

I look forward to the second round!

You are welcome! Glad to see support for this project.

 

[pk2carlos]

I'd like to thank you for your efforts in providing objective data despite what seems like constant criticism directed towards you throughout this thread and the other thread you created.

I look forward to the second round!

+1

Also it would be interesting to see difference in mesurment after the breake-in period.

 

[xrk971]

I plan to show the measurement and the sound recorded before and after. I think a lot of break in may have more to do with the low frequency extension. Maybe others who have an A7.3 can comment. So in a FAST with a XO at 225Hz it may not be so obvious. But nonetheless I am breaking it in to ensure the best possible performance from this driver.

I boosted the volume up a bit from low to medium after first 24hrs.

 

[zman01]

xrk971,

It will be great if you can put a put a foam-core "ring" around the thick bezel of the Alpair 7.3 when taking the measurements - that will help maintain the flush-mounting that is recommended for MA drivers with thicker bezels.

On break-in, I recall a perceptible "opening up" of the sound for Fostex FE166EN drivers and MA CHR-70.2 roughly around ~30 hour mark. Those were some early ones I tried out, and afterwards I've usually done driver break-in out of earshot, so can't comment too much.

 

[xrk971]

Zman,
Good point about the foam bezel for flush mount. I did not use the optional decorative bezel which would have made it extra thick. Although for the blind listening test I will make a foam core flush mount ring, the before break-in measurement was made without it so for comparison, the after break in measurement will have to be without the flush mounting.

So do I need to do 200hrs of break in? Seems like a long time. If you heard differences at 36hrs, maybe 48 is enough?

 

[zman01]

Zman,
Good point about the foam bezel for flush mount. I did not use the optional decorative bezel which would have made it extra thick. Although for the blind listening test I will make a foam core flush mount ring, the before break-in measurement was made without it so for comparison, the after break in measurement will have to be without the flush mounting.

Ok, but in that case can I request you to take one extra set of measurements with limited break-in (the few hours that you have on 'em now) with the foam core flush mount ring? Keep the data with you, might come in handy.

So do I need to do 200hrs of break in? Seems like a long time. If you heard differences at 36hrs, maybe 48 is enough?

It does seem like a loooong time, especially playing soft music! But hey - you like nice stuff like Norah Jones and smooth jazz, so time should fly past.

But after all, that is the manufacturers recommendation and not for me to comment/suggest otherwise. I'd say get as many hours as you can without holding up things too much, no pressure.

 

[Bob Brines]

Don't get too carried away with "soft". 70dB@8' is about right for break-in. Much softer and it will take forever to break in an MA driver. As I remember for discussions with Mark, just don't exceed 1mm excursion.

Bob

 

[ra7]

Break in aka getting used to the sound.

Why does the sound always improve after break in? Why doesn't it get worse?

 

[ra7]

X, you should start a new thread/poll for the new set. Don't mix it with the previous results.

 

[xrk971]

I plan on making a new thread. I only break in because it's recommended for this driver. It's actually wrapped in a blanket and in a plastic cooler box now so I don't have to hear it

 

[planet10]

Break in aka getting used to the sound.

One only needs to have 2 pr of the same speakers side-by-side with differing level of break-in to know that that is not near the whole story

dave

 

[Godzilla]

>>> Why does the sound always improve after break in? Why doesn't it get worse?

That's an interesting question.

I think break in is simply the drivers mechanical parts loosening up after several hours of use. Once this occurs the driver should perform to spec until it begins to get old and its parts begin to wear out.

 

[freddi]

wouldn't just two drivers with a good "mono" (or just one channel of 2-channel) recording suffice for comparison?

reA130 - my very old sample goes to about 13KHz on axis - pretty good considering a soft dust cap (almost like some dome tweeters)

 

[xrk971]

Measurement of A7.3 after 36 hrs of break in.

 

[gazzagazza]

For interest here is an Alpair 7 installed in the Pensil enclosure designed by Scottmoose. This is an in room pink noise measurement. One channel only. There is only the Alpair 7 operating. Nice LF extension and an overall tidy response.

 

[xrk971]

Thanks for posting that - it is a very nice in room response. I do see vestigial remnants of the 10 and 13kHz peaks but much lower in amplitude. This must be the first posted measurement of an Alpair 7.3 in a Pensil I have seen.

 

[BYRTT]

gazzagazza,
Nice in room response is that at off axis 15º spot where it seems be more smooth.
Plot data from xrk971 can be compared this link where a A7.3m Enabled is measured on a 120dB scale on axis 15º 30º and 45º.
Joseph Crowe's DIY Speaker Building Blog: Summer Rain Project Part Four