stevie

[quote name='Phil Starr' post='909800' date='Jul 30 2010, 12:14 AM']The figures show the sort of increase in compliance you would expect after a breaking in period though why Qes would change beats me.[/quote] Because Fs is part of the equation for Qes: Qes = 2pi x Fs x Mms x Re/ (Bl)2. If Fs drops, so does Qes.

[quote name='wateroftyne' post='910949' date='Jul 31 2010, 09:00 AM']Given the above, you just need to ask yourself if a minor cosmetic issue bothers you enough to take it back. And that will be your answer![/quote] It would do my head in every time I picked it up :-) Anyway, if I'd paid a grand I wouldn't accept sloppy workmanship, even if it did sound OK.

[quote name='escholl' post='910485' date='Jul 30 2010, 05:56 PM']So, as I understand it, 4 hours (or possibly less?) of use may make a slight difference to the low end response of a dipole enclosure, otherwise the difference is negligible?[/quote] Despite thousands of unsubstantiated claims to the contrary all over the internet, yes. The driver itself changes quite a lot, but its real-life performance in a box doesn't.

[quote name='escholl' post='909780' date='Jul 29 2010, 11:48 PM']Can you give us more information on exactly what you did, and how you measured and obtained these results? What was your break-in procedure?[/quote] I used Liberty Audiosuite, an industry-standard measurement system, to measure the Thiele Small parameters of the driver straight out of the box. I used the added weight method to find VAS. I ran the driver in with a 20Hz signal from a signal generator into the unmounted driver for about 4 hours, I think. I normally leave them running overnight but fs had dropped to below the manufacturer's spec - so I thought that was enough. If I’d known the data was going to be nitpicked, I would have measured several times to eliminate some of the inconsistencies. The only thing that running-in does is to reduce the stiffness of the suspension. So, VAS is raised and fs and Qts drop. If you compare the green and blue curves of the simulation, you will see that these changes are self-cancelling because the curves for both drivers are virtually identical. (There seems to be a few bugs in my modelling software, because the f3 point is obviously the same, and not different as it states, and there is also a contradiction in the nominal efficiency figures and the 1W SPL figures.) Still, it’s the big picture that counts :-). My conclusion would be that running a speaker in makes no difference to its frequency response when mounted in a reflex or sealed enclosure. I would expect the lower fs after running-in to be audible in a dipole, or an open-backed guitar cabinet, however, because VAS is more or less irrelevant to the performance of these boxes. Horns, as mentioned by Lawrence, may be similar, but that’s not my field. Al, the measured frequency response differences of the 'before and after' driver mounted in a cabinet are negligible. I would not expect any audible difference. If there is an audible difference between a driver before and after running in, I have no idea what might be causing it, but I think escholl put his finger on the most likely cause earlier on. Did anyone mention cable burn-in?

I'll provide more details later today when I have time. Just bear in mind that there is a margin of error here - there is no reason for the cone's moving mass to have changed, for example.

You can blow any HF unit in about 10 seconds by driving it with an amp that's clipping. If you want to test a tweeter protection circuit, that's the easy way to do it - the only way to do it, in fact.

Here is some data on an Eminence Kappalite 3012LF, with measurements before and after running in. There are a few minor discrepancies, but this was not designed as a scientific exercise: I was simply checking the parameters against the manufacturer's figures. The parameters on the left are for the new driver; the ones on the right are the same driver, but run in. The interesting information is on the right - a simulation of how they perform in an identical box. I can't say this is conclusive and absolute, but it's certainly repeatable by anyone who wants to do so.

[quote name='LawrenceH' post='909433' date='Jul 29 2010, 04:39 PM']But really, if someone couldn't tell the difference between the 'fresh' Deltalite II I tried versus the same unit with a few hours' playing time, then they have ears of cloth. And I definitely am not a subscriber to weird voodoo hifi magic about solid gold interconnects, bi-wiring or all that rubbish.[/quote] Although you will admit that accusing others of having ears of cloth when they don't agree with you is exactly how such people behave.

[quote name='LawrenceH' post='908052' date='Jul 28 2010, 12:00 PM']Not wishing to derail this thread but speaker break-in is very real and easily measurable.[/quote] This, of course, depends on how you define speaker break-in.

[quote name='gary mac' post='774926' date='Mar 15 2010, 09:27 AM']Once I have shown this thread to my good wife, I'm suspecting that she will never ever moan again about my collection of basses again.[/quote] Now there's a good idea!

Seriously though I normally get that sound with my back Jazz pickup (I have a P/J). Plus a touch of 2kHz lift on your amp maybe. I believe your bass has a rear Jazz pickup. So you have no doubt tried getting your sound using just the back pickup. Hmmm.

[quote name='The GroovyPlucker' post='907634' date='Jul 27 2010, 10:04 PM']Not sure you can get that piano clang with a Fender....[/quote] I agree. Have you thought of trying a piano?

The ad is confusing. The item is listed as 'For parts or not working' but the description says its in good working order. Plus, bidders identities are being hidden, which is always a bit iffy. And, of course, it's only been up for a day.

[quote name='Mr. Foxen' post='906191' date='Jul 26 2010, 06:51 PM']Sensible sized voice coil says not some silly rated car sub.[/quote] Yes, you can also tell from the double roll surround that they are a PA driver. I don't expect these are going to be amazing, but for that price it's worth taking a punt because you know you'll always get your money back. Some of the Asian loudspeakers can now match what is available from the top European makers - and at a much lower price. I couldn't quite tell from the photo, but these may even have had a cast chassis.

The Complete Electric Bassist is by far the best book published to help you learn to read for the bass guitar, IMO. Only available secondhand now, it leaves others in the dust. It's such a shame they didn't publish volume 2. For a bit of variety, dig into the Major's Boot Camp here in the Theory and Technique section. The Major covers a lot of the same material but in a more modern way.

Here's a pair of neo 15" bass drivers for those interested in reducing the weight of their cabs. They look like the usual Celestion/Monacor fare. Currently at £51 with not much interest - probably because they're in the DJ section. [url="http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130411685095&ssPageName=STRK:MEWAX:IT"]http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...e=STRK:MEWAX:IT[/url]

I do so enjoy the intelligent exchange of views and information here on Basschat.

[quote name='PauBass' post='900579' date='Jul 20 2010, 10:48 PM']I can't find it [/quote] I've just checked and there are chrome ones on there but no black I'm afraid.