stevie

[quote name='Phil Starr' timestamp='1355184012' post='1895267'] I don't think there can be any doubt that the compliance of the spider and the surround will change over the life of a loudspeaker and that this will change the Thiele/Small parameters. Without any data (sorry) to back this up I would guess that this would follow a decay curve with rapid changes at first slowing down as the speaker ages but never reaching a point of no further change. I've seen the fs/Qts/Vas argument though the only reference to this in my 4th edition of Dickason this is about manufacturing spread, not breaking in. [/quote] Hi Phil, Modern drivers are designed with materials that tend to be fairly stable. I don't think the parameters change very much over time, at least not on a good quality driver. I checked out a 25-year old JBL 12" not so long ago and it met the manufacturer's T.S. specs. The Dickason I was referring to was the 7th edition. I'll post the whole section when I get time to type it out. [quote name='Phil Starr' timestamp='1355184012' post='1895267'] I'd love to see any data anyone has though. [/quote] I'll post Dickason's before/after break-in measurements later because they're in the relevant section in his book. Here are the measurements I took of an Eminence Kappalite 3012LF (fresh from its sealed box) last year. You can put them in your own modelling software if you wish or refer to the curve on the right. As you can see, the curves are indistinguishable.

[quote name='Bill Fitzmaurice' timestamp='1354628075' post='1888317'] Loudspeaker designers don't debate break-in amongst themselves, for the same reason. But pundits will jabber on forever. [/quote] Actually, they do. You’ll find qualified designers all over the internet trying to explain that speaker break-in is a myth perpetuated by sales and marketing departments. The science involved is so basic that it's in the Loudspeaker Cookbook, written incidentally by a qualified and respected designer, Vance Dickensen, also editor of the industry’s trade journal Voice Coil. Vance Dickensen writes that [i]after break-in “enclosure requirements and performance are nearly identical[/i] since the Fs/Qts ratio stays virtually the same” and that, although there are measurable changes in driver parameters after break-in, [i]any changes in response will be inaudible[/i]. He backs this up with data, of course. He also says, [i]“Do you need to ascribe a particular time period for "break-in"? No.[/i] Just plug it in and play it like you normally would.” Very sensible advice and a direct answer to this thread’s original question. Floyd Toole thinks that speaker break-in is a myth too. Described by the Audio Critic as “arguably the world's leading authority on loudspeakers”, he was Head of Acoustical Engineering at Harman International Industries (JBL, Studer/Soundcraft, Crown, dbx, BSS, Lexicon, AKG, Revel) for 15 years and set up the Harman speaker testing labs, which are world renowned. He is an acknowledge expert on loudspeaker testing and psychoacoustics. I copied this short passage on the subject from his book: Sound Reproduction - Loudspeakers and Rooms. “In parts of the audio industry, there is a belief that all components from wires to electronics to loudspeakers need to “break in.” Out of the box, it is assumed that they will not be performing at their best. Proponents vehemently deny that this process has anything to do with adaptation, writing extensively about changes in performance that they claim are easily audible in several aspects of device performance. Yet, [i]the author is not aware of any controlled test in which any consequential audible differences were found, even in loudspeakers, where there would seem to be some opportunities for material changes[/i]. A few years ago, to satisfy a determined marketing person, the research group performed a test using samples of a loudspeaker that was claimed to benefit from “breaking in.” [i]Measurements before and after the recommended break-in showed no differences in frequency response[/i], except a very tiny change around 30–40 Hz in the one area where break-in effects could be expected: woofer compliance. [i]Careful listening tests revealed no audible differences. [/i]None of this was surprising to the engineering staff. It is not clear whether the marketing person was satisfied by the finding.” By the way, this book gets a glowing recommendation from Siegfrid Linkwitz on his site, where he says, "It debunks much of the BS that seems to have permeated the audio industry and many of its customers.” Now, guys, if we are going to contradict some of the most respected and erudite experts in the business, I suggest you respond to my previous requests for some [i]evidence [/i]to support the non-scientific, anecdotal assertions we have heard so far. Would that be too much too ask?

Assuming the measurement you took was correct, those drivers are not 8 ohms. I've never seen an 8-ohm driver with a DCR that low. Let me tell you about a trick some speaker companies have been known to pull. They fit 6-ohm drivers to their cabinets and label them 8-ohms. Why? Because it makes the speaker louder than the competition in the showroom. It only becomes problematical when you connect two speakers to one amplifier channel. However, at loud volumes where you would expect the amp to complain, the speaker impedance rises, neatly solving the problem. The worst example I've seen of this was the Zeck 15/3 PA speaker, unknown over here but a best-seller on the continent a couple of decades ago. They had the nerve to fit a 4-ohm EV driver to their 8-ohm box. The magazines raved about how much louder it was than anything else but none of them ever bothered to measure it.

[quote name='alexclaber' timestamp='1354269305' post='1884213'] In a typical bass cab this will result in an increase in output between 50Hz and 100Hz - you can measure this and you can model this. And you can hear it! <snip>.... you'll hear a fresh woofer as having noticeably less bottom than a loosened up one. [/quote] This is impressively specific. If there's "noticeably less bottom" I'd expect at least a 3dB rise between 50 and 100Hz, wouldn't you agree? I'd be very interested in seeing the data you've used to arrive at this.

It sounds like people are finally realizing the benefits of fitting high quality drivers. It's about time.

[quote name='andyjingram' timestamp='1354361613' post='1885154'] Stevie, I listened to the youtube clip, and as poor as the sound quality is, are you saying that you genuinely hear no difference whatsoever between the two speakers? Yes, the playing is inconsistent, and the changes are extremely subtle, but they are there in the way I have experienced with many guitar speakers in the past. I just want to emphasise the word [i]subtle[/i] here. We are talking about fractional, but audible differences. You make a good point about people believing that they hear (or saying that they hear) what they are told to expect by advertising or snake-oil hearsay. That is true, and part of human nature to a degree- how many non-musos have asked you why you don't play a Fender through a Marshall, because they 'know' they are 'the best'? There are no doubt people who agree on speaker break-in without ever having heard the difference or without the ability to hear it, but that doesn't make it untrue. [/quote] Good post. I didn’t think the sound quality was that poor actually and yes, I thought I might have heard a difference, although not consistently from one sample to the next. But I’ve learned to be very sceptical about what I think I hear because I know how easily it is to be fooled, especially when differences are minor. I would say straight away that I haven’t carried out any testing on guitar loudspeakers and wouldn’t argue against any claims that they “break in” or change over time. I simply don’t know. I can think of a couple of reasons why they might: 1) they are often used in open-back cabinets where a change of driver resonant frequency will impact differently on system response than in an enclosed cabinet, and 2) they are based on "old” materials (such as paper surrounds, non-impregnated cones, etc.) that are more liable to change – and keep changing - than modern materials. Although that video is interesting, there are a couple of reasons why the comparison is flawed and why anyone should be cautious about drawing any firm conclusions from it. Firstly, the level and quality of the test signal is inconsistent. As the guitarist is using a particularly horrible distortion sound, my personal preferences were directly related to the amount of distortion I heard. That is, I preferred the (quieter) clips when there was less distortion. Or to put it another way, I probably equated differences in the original signal to differences in the speakers. Secondly, there were no real controls. In particular, there were no measurements to determine whether, for example, the first speaker was identical to the second. If they were different to start with (quite possible), all bets would be off. Thirdly, we know in advance which speakers are being played in each clip. This invalidates the comparison because of expectation bias, the process where you listen out for cues that confirm what you expect to hear and ignore cues that don’t. In controlled listening tests, even the most skilled and practiced listeners will hear things that are not there if they expect to do so. For any opinion on this comparison to be valid, a listener would have to identify each speaker correctly in 10 out of 12 of clips without knowing which was which. Do you think you could do that? The reason I posted the YouTube clip initially was because of the comments: all of the people who left comments thought the broken-in speaker was better, mainly because they thought it was “smoother”. This should ring warning bells immediately because, as we know, one man’s “smooth" is another man’s “lack of high-end sparkle”. I suspect that if this video had been posted with the captions reversed, the response would still have been 100% in favour of whatever speaker people thought was broken-in. You never hear of a run-in speaker sounding worse, do you? That soft bass never becomes softer; it always becomes tighter. And that lean bass never becomes thinner; it always becomes fuller. Interestingly, I didn’t hear any difference in the bass response between these clips. To demonstrate why what you expect to hear can override what you actually hear, check out this YouTube clip on the McGurk Effect. [media]http://www.youtube.com/watch?v=G-lN8vWm3m0[/media]. Definitely worth a minute of your time. So, although none of this proves that speaker break-in does not exist, it does provide an explanation of why people might believe they’ve heard a change in their speaker when it hasn't changed at all. Especially if they’ve been told categorically by an expert that the sound will change and they then become a stakeholder in the whole process by downloading a burn-in file or CD and/or spending weeks playing pink noise through their system. And of course, they want to believe: they don’t want to admit they have made a mistake and they certainly don’t want the hassle of taking their speakers back to their dealer. (This is a bit Derren Brown, but I’m sure you get the picture). It's very easy to measure whether there’s a difference in the frequency response of a speaker in a cabinet before and after running in. I’ve done it. These measurements are reproducible and repeatable. I also posted a link earlier to someone who did the same thing in a more thorough manner than my efforts. Why do people believe in burn-in when there's no evidence for it? Well, it's a long story but it boils down to the fact that the longer you break your hi-fi components in, the less likely you are to return them. It’s a sales technique. And a very effective one too. Ask the people who sell two thousand dollar cables.

[quote name='Mr. Foxen' timestamp='1354311065' post='1884817'] So by saying 'not audible', you are meaning not audible to you personally because you can't hear the system, rather than actually being audible to people hearing them? Or the rule only applies to stuff you've heard? Or "not audible in the context of a speaker system" only applies to speakers where it doesn't, and systems where it does they are 'a different animal'? [/quote]

I don't know what's audible and what's not audible in your speakers, Mr. Foxen. I've never heard them.

Guitar loudspeakers are a different animal. And just to clarify, I'm not saying that drivers don't 'break in'; I'm suggesting that break-in is not audible in the context of a speaker system.

Could be a misaligned or damaged voice coil. I'd consider talking to Thomann and seeing if they'll send you out a replacement tweeter. It would be easier and cheaper for them - as long as you can fit it.

[quote name='Bill Fitzmaurice' timestamp='1354283625' post='1884428'] The running in of a car isn't a very good analogy. The wearing in of a pair of new unwashed jeans or leather shoes is, because they get softer with use, as do the suspensions on drivers. Like Alex I don't recommend breaking in drivers just because I think it might be beneficial, it's because I've measured the results of break in, literally hundreds of times. I very much doubt that the wags who say it doesn't do anything have any data to back up their assertions. [/quote] It's true that a car isn't a good analogy. Neither are shoes unless you are planning to stick them on your feet and walk in them. The wags who say it doesn't do anything are the only ones who have published data. The "burn-in" camp relies on anecdotes and assertions. Here is someone who carried out exactly the same tests as I did and came to the same conclusion: <http://www.audioholics.com/education/loudspeaker-basics/speaker-break-in-fact-or-fiction>. For those who have better things to do, the conclusion this person comes to is "From the foregoing analyses, it's reasonable to conclude that suspension compliance changes arising as a consequence of initial driver burn in has little effect on the performance of a loudspeaker system." And there's plenty more where that came from. As you've measured the results of break-in hundreds of times, Bill, it surely wouldn't be too difficult for you to supply the "data to back up your assertions."

I think a lot of it has to do with the way the paper surround softens up over time, Mr. Foxen.

[quote name='andyjingram' timestamp='1354200995' post='1883491'] I think that outside of the audiophile world, the only real concern with speaker break-in is in guitar amps. Distorted guitar can sound noticeably unpleasant through a fresh speaker, and starts to 'open-up' over time, something guitarists are keen to get through rapidly. [/quote] Here's a video on YouTube showing a comparison between a new and a 'broken-in' Celestion guitar speaker: <http://www.youtube.com/watch?v=JGjMhHKP7Go> It's well done but quite unscientific in that 1) you know which speaker you're listening to and 2) the volume and particularly the amount of distortion changes depending on how he plays his guitar. Anyhow, what is interesting about this is the comments. Given that there is no marked sonic difference between the two speakers (although you are welcome to disagree) [i]everyone[/i] who has left a comment prefers the broken-in speaker. Now isn't that strange? I really liked this comment (I think he was serious): "It's obvious the broken in speaker is CLEANER than the new one. The new one seems a bit 'stiff'."

The same thought occurred to me. Doesn't anyone open their cabs up and look inside? (Must just be me then).

4String, have you considered that your experience could be down to listener break-in? Expectation bias is a very strange thing. I remember being convinced of the superiority of my £100 interconnect cables until I recommended them to a friend and we compared them with the free ones that came with his amplifier. Of course, in those days when you got a new item of hi-fi equipment the first thing you did was to bin the free cables supplied and replace them with a pair from a boutique maker made from 99.999 percent oxygen-free silver-plated copper. When I first took my swish cables home I plugged them in and was convinced they sounded better. After all, they looked better, a very knowledgeable salesman had assured me that they would sound better, they had good reviews in the hi-fi press and were manufactured by a company with a million dollar turnover making all kinds of scientific claims that sounded very convincing. Expectation bias, you see? A few years later when I compared them to my friend’s cheap cables, I wasn’t aware which was which - and guess what? I couldn’t hear any difference. Nothing at all. They sounded identical. I’m curious about two things. 1. If breaking a speaker in makes a difference, why is it always a difference for the better? 2. For all the people who claim to hear a difference in their speakers after break-in (where there is no measurable difference in the system frequency response) why doesn’t anyone notice a difference in their speakers after they’ve been playing them for a while? After all, driver parameters change as the voice coil gets hot and this has a very real effect on frequency response that you can in fact measure.

I can't see any reason why not.

There are lots of examples of products selling on eBay for much higher than the rrp. I bought a cable directly from Sennheiser for £15 that eBay traders are asking £25 for. People assume that stuff is dirt cheap on eBay - and it usually is. But not always.

I'm sorry, but running your speakers in is a completely pointless exercise. It's an audio myth. Your speaker is not a car engine. Sure, you'll soften up the suspension of your drivers but the lower resonance frequency (Fs) will be balanced by an increase in compliance (VAS) and there will be no difference in the sound of your cab. Of course, if you're expecting to hear a difference, chances are you will hear one. Then there is the matter of whether you can actually tell whether the sound has changed (even if it has) when there is a long gap between listening tests. A year or two ago when this subject was being discussed on here I measured the Thiele-Small parameters of a factory fresh Eminence 3012LF. Then I ran it in and measured again. Of course, the parameters had changed but when I modelled the frequency response in a box there was no difference. I published the results and they should be on this site somewhere. I didn't realize at the time that greater minds had done this before me. Just play the cab and stop farting about. [Edit] I would add that there is a greater chance of damaging your speaker by playing a very low test tone through it (at a frequency that the cab is not designed to handle and where the driver has very little excursion capability) than playing through it normally.

[quote name='voxpop' timestamp='1353345096' post='1873998'] Would I be better off perminatly blocking off the cab ports / holes and making a sealed cab with the celestion driver. [/quote] As Lawrence says, you'll reduce power handling a bit, but that Celestion driver has a very high Qts which is more suited to a sealed system. The undersized magnet syndrome strikes again.

[quote name='bremen' timestamp='1353344945' post='1873992'] My preference is also flat, but humps and bumps in the right places can add to the character of a sound in a positive way, wouldn't you agree? [/quote] If you're lucky, yes. The problem is that the frequencies with humps and bumps are often accompanied by other problems that you don't want (like resonances, distortion, suckouts). Better to have a clean, smooth (though not necessarily flat) frequency response that lets your 'tone' shine through. Then dial in your 'character' before it gets to the speaker. I know others take a different approach, and that's fine, but I don't want my speakers to add colour.

Massive humps and bumps have no place in any speaker system. They are usually caused by bad design or skimping on cost. The 100Hz bump that is common in bass guitar cabs is usually caused by using an undersized magnet to save money.

Back home now. The family had lunch at the pub (good prices) and then left to have a wander around Sherborne. I had a whale of a time trying out all the lovely gear and was particularly impressed by a great-sounding Sandberg that I'll never be able to afford, but never mind. A big thanks to John (oldslapper) and Yorks5stringer for all their good work in organizing everything. I'll try to bring an amp and a cab next year!