Yes I have been using JBL's T/S for years and never had an issue. There are some typo's though. E-145 VAS is a prime example.
Rob 🙂
Rob 🙂
Agreed, but can a few Hz shift in Fs result in a 'stunning' improvement in sound following burn-in, as described in a previous post? I am a fairly critical listener (without claiming to have Golden Ears!), but my perception of the 'quality' of my very familiar system unchanged over years can alter daily depending upon little more than my mood at the time. A familiar track can go from mere background noise to almost having me in tears of emotion, yet nothing has changed. To make any statistically viable evaluation over time is self-evidently futile, however expectation bias has an enormously powerful effect, and should never be overlooked.
I have digressed from the OPs question radically and have not answered his question, for which I apologise. My advice is to be aware of TS parameter shift with use when designing speakers but ignore completely it if buying them ready built. Crack open a bottle of that vintage red I alluded to, don't fret, and enjoy your music. A tragedy befell me recently which really does make life seem too short to worry over too many minutiae.
Correct, many descriptions. I have read over the years on forums sound like assumptions
or people parrot what they told they are suppose to hear.
Most the time I disagree with most the break in myths
Far as real world, having assembled many systems as a teen for a Flea market vendor.
Heard many drivers out of the box. Only the accordion edge speakers
had any noticeable change. And my boss was aware of it. " Break in" was not too complicated.
We always had Music playing on multiple speakers for people walking by the vending tent.
When ever a system was built for a customer. We played music through it before they picked
it up. " Groud breaking" technology. And he wasnt gonna waste time or money
to rotate display speakers. But was well known about 45 mins to a Hour was all it took
for the woofers. And was picky about the common Sealed back mids.
Otherwise foam edge speakers, confirmed the crossover was ok, and if tweeter was reversed
on some of the systems. No burn in. Pointless they dont change , or at least not audible
He had 2 pallets of 18" speakers for particle board Vega copies we made
And those took a few hours to loosen up. Never bought them again.
Edges were gooped very heavy and he wouldn't sell them unless run for that time.
I could staple the cab together in about 30 mins. He peeved and moaned because about
3 hours to carpet. So not a same day pickup. Any 18" cab built had signal on it the next morning
and run all day before he let it go out. Its basically just the goop edges and not much more
than a few hours, as far as being " Audible"
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Sure. But it'll depend on the degree of the shift / the driver, and in some cases likely the room. I've had several units from Sb for instance that went from having an out-of-box Qt of about 0.48, a Vas of about 11.3 litres & an Fs of about 43Hz drop after an hour of being pushed to just below their mechanical limit to very near the factory values of 0.31, 20.2 litres and 33Hz respectively. Give or take, call it a halving of Vb, and a shift in Fb of about 7Hz for roughly the same target alignment. Definitely audible if the program material permits; drop it in the same larger, lower-tuned box & it's not so great -narrower tuning, peaking at Fb, some losses an octave above, excursion getting right on the limit at Fb. That's assuming a stock flat alignment with modest damping & leakage -I wouldn't do that in practice, but gives an idea that it can make a difference in certain situations, albeit one that I agree is certainly over-stated in many cases.
Do you think that in a case where driver has been "accelerated" by hand, could return to "normal" after it has been used many hours with low frequency?
Just asking because i think i have been also using my hand a bit to accelerate burn in iwth my AT 18h52 drivers, i started doing this after troels told me to do this in his documentation of faital.. If this means i have spoiled my drivers.. curses!!
No that is still very far from exact.
Which voltage, which type of signal can make a significant difference. Especially when the Bl(x) and Cms(x) isn't linear.
Also some calculate the Re by an extrapolation method. The list goes a little further.
None of this is stated in the little text you just quoted. Proving how big the mess really is.
No, you're fine, given its a rubber surround equipped driver. Its the ones with coated accordion surrounds that are more sensitive to manual break in by hand. Some people will argue against this theory, but it can affect certain mechanical parameters which affect suspension linearity and as a result, HD performance in the lower mids, where driver suspension compliance prevails more than enclosure air spring. Drivers with accordion surrounds have less linear suspensions than those with elastomeric surrounds and large, very compliant spiders.
Well, we may not know much about test signal types in specific cases (unless explicitly mentioned), but I guess there should be some kind of standard for those things.
Though details of measurement are not mentioned, it is clearly stated that a two-hour conditioning at the specified (AES) power would get it done, so I think that answers the question, at least for the JBL brand. Thus, from the burn-in point of view, most users simply want some clue from the manufacturer as to how long it would take to get the parameters to steady state, which is I meant to show by citing that text.
So, are you saying that if you hear it and understand it, and if it has a particular sound, then everyone who describes it as having that particular sound is not parroting, but if you don't hear and or don't understand it, yet other people do hear it, then its parroting and a myth?
Is what it is, I guess.
I just had a opportunity to hear a lot of speakers.
Think you edited and quoted it well.
Only thing noticeable was the accordion edge speakers
I just had a opportunity to hear a lot of speakers.
Think you edited and quoted it well.
Only thing noticeable was the accordion edge speakers
Gilbert Briggs said that speakers need burn-in in the 1950s, and he should certainly know. Worked for Wharfedale and all that.
But he didn't say 200 hours. I never believe those huge numbers. They seem to be just designed to exceed the warranty period.
But he didn't say 200 hours. I never believe those huge numbers. They seem to be just designed to exceed the warranty period.
Yeah, some folks took exception to my 'it's not broken in, it's broke'! response to such long hours.
There most definitely should, but at this moment (and for years) it's a big wild west unfortunately.
There certainly should, for T/S measurement. Unfortunately, it wasn't helped by Thiele, D'Appolito & others stressing that T/S parameters are small signal and that level is either unimportant, or even should be as low as practicable. In the intended context -fair enough. More broadly, it doesn't necessarily work out quite so well.
Call this subjective, because it truly is. When I first installed my AN 15 Alinco full range drivers I was awe struck at the stunning vocals, but quite underwhelmed at most everything else. I knew that I was going to have to work them into a multi driver system. None the less, I dutifully let them run 24 x 7 for a forgotten number of days. When I next listened to them I could hardly believe that they were the same drivers. Vocals were still wonderful, though less obviously so due to the fact that everything, perhaps everything else, was so improved. Gone was the idea that these would need to be a part of a multi driver speaker. Bass could be better, treble too perhaps, but overall I had never heard a better sounding speaker that I could live with as is. Quad ELS57s may, aural memory sucks, have bettered them in some ways, but I couldn't live with their low volume levels. There was nothing subtle about the improvement, and I hadn't grown to anything because I hadn't been listening to them, and was skeptical that they would ever work as single drivers. We're these an exception to the rule? Likely because I had never noted a change in my previous speakers. YMMV
There aren't any rules as such, so probably not. They were likely just doing as described above -suspension loosening up to spec. This is straightforward with most LF units etc. as you can simply put a sine-wave through them, at or just below Fs & crank the level so they're just below the limit of mechanical travel. 10mins of that will get you most of the way there; call it 30mins if you want to be conservative. It's more of a risk to do that with wideband drivers, although short-throw types tend to get there quicker if you're careful. If you prefer to be conservative, a lower-level run will do the same, at the price of it taking longer. The old W.E. / Altec etc. units as GM pointed out were good 'fresh from the box', but a lot of more recent units (usually rather cheaper 😉 ) tend to be a bit more 'generous' with the old suspension adhesive / lacquer so again -probably a bit longer than some of the earlier drivers.
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"simply put a sine-wave through them, at or just below Fs & crank the level so they're just below the limit of mechanical travel. 10mins of that will get you most of the way there; call it 30mins if you want to be conservative. It's more of a risk to do that with wideband drivers..."
What is the risk attached to running wideband drivers below Xmax?
What is the risk attached to running wideband drivers below Xmax?
When they were still selling drivers to the public ATC said that driver burn in is definitely a thing but also that their drivers are 'burned in' during their quality control and testing procedure they perform on every driver.
Historically, starch or similar has been the chemical stiffener that if abused while still new before it's completely dried out leaves one with a limp rag of sorts, though one can use cheap lacquer hairspray or similar for fine tuning and other chemicals for more extreme stiffness to dial it back in to 'taste' like me and some other old-timers here routinely did (do?).
I have experienced a possible related effect after changing my regular TV viewing position from a sharp angle at the left side to a sharp angle at the right side. After the change the screen looked like a irregular quadrilateral, while before the change it looked like a rectangle. And since I use the same brain for listening to music ...