Capacitors, ceramic or poly?

[Al Heeley]

It has to be true, I read it on the interweb.

[Prosebass]

[quote name='Al Heeley' post='908272' date='Jul 28 2010, 03:17 PM']Tant caps have high tolerance (accurate value) and are (mostly) polar so cannot always be used to replace standard non-polar types. They can blow quite easily of you get them too hot whilst soldering or if you have the polarity the wrong way round.
Cheap ceramic caps can be +/- 10% of the printed value, which tbh makes little diff on a bass guitar tone pot.

[url="http://www.engineersedge.com/instrumentation/tantalum_capacitors.htm"]http://www.engineersedge.com/instrumentati..._capacitors.htm[/url]
Fascinating stuff indeed.[/quote]

+1

can't beat Metallised PETP film capacitors from CPC

I use them because they are orange.

Now what about the quality of the pots ?

Edited July 28, 2010 by Prosebass

[Mr. Foxen]

[quote name='escholl' post='908416' date='Jul 28 2010, 04:52 PM']The differences between a "broken in" speaker and one which is not, are in nearly all cases less than the difference between two of the same speakers -- that is to say the difference is less than the manufacturing tolerance for that speaker. If you are able to provide accurate and repeatable measurements to the contrary, than please do so, I would love to see it. However, all data that I have seen to date indicates "speaker break in" to be a psychoacoustic phenomenon, and more likely has to do with your ears getting used to the way that speaker sounds, or simply just the individual hearing what they expect to hear.

Edit: Slightly further research brought up mention of a paper published by David Clark and available through AES, which discusses measurable "speaker break-in" that occurs in the first few seconds of use, after an extended period of non-use. This is likely not the sort of "break-in" you were thinking of however. [/quote]

From [url="http://barefacedbass.com/faqs.htm"]here:[/url]
[quote]Do I need to 'break-in' the cab?

Not really.

During the first ten or twenty hours of use the speaker's mechanical make-up changes somewhat as the cone bellmodes become more evenly distributed and the suspension softens, resulting in a smoother clearer and deeper (and all round better!) sound. The change is most noticeable with the Big One which sounds like it's gained almost another octave of lows between being brand new and broken-in. However this does not mean you have to baby the cab as you would when running a car in, they can still handle full power when fresh - just look forward to the tone getting better as the woofers loosen up.[/quote]

Nerd fight!

[escholl]

[quote name='Mr. Foxen' post='908797' date='Jul 29 2010, 12:58 AM']Nerd fight![/quote]




but on a nerdy note, I had this discussion with him once, and told him that when he could provide the objective data I would be all ears. He never did, but he is pretty busy. Till then, I stand by my statement however. I will be doing a masters in audio acoustics this year or next, and am planning a doctorate after that, so hopefully I will finally be able to resolve this once and for all in the next few years!

[ShergoldSnickers]

Declaration: This is not scientific - merely experience on my part

I've gone through several pairs of hi-fi loudpeakers, the latest of which I still have after nearly 20 years, a pair of Epos ES14s, originally bought as monitoring for a recording studio. I bought these after a protracted audition at a colleagues house, but when I got my new pair home, was surprised at how bass light they sounded.

They had been bought direct from the designer, a chap called Robin Marshall, and because they were for studio use, he supplied spare drivers as we were just slightly concerned about high SPLs damaging them. We needn't have worried, the bass drivers would need putting across the mains to break them, and we could only get a treble driver to fail by wiring it direct to the amplifier output - no crossover, rolling the bass end off from the desk and pushing a real bastard of a hi-hat and cymbal loop at it, everything full on for half an hour. Eventually the aluminium dome shattered!

A few years later.... the glue on one of the drivers went, around where the coil former meets the cone. I Put the spare bass/mid driver in and instantly got the bass light sound on this cabinet only. It went after a day or so. It could be psychoacoustics, but the difference was marked, and on balance I'd plump for the driver rather than perception, but can't absolutely prove either one over the other.

[Mr. Foxen]

[quote name='escholl' post='908836' date='Jul 29 2010, 05:56 AM']


but on a nerdy note, I had this discussion with him once, and told him that when he could provide the objective data I would be all ears. He never did, but he is pretty busy. Till then, I stand by my statement however. I will be doing a masters in audio acoustics this year or next, and am planning a doctorate after that, so hopefully I will finally be able to resolve this once and for all in the next few years! [/quote]

There was an email exchange with one of the Celestion engineers about speaker break in on some other forum, he said the sound of a Vintage 30 does change but it is supposed to sound right from the box, so the bottomier tone after they are played in (favoured for Doom) is actually the sound of a worn out driver. It is fairly noticeable with guitar drivers when you are expecting lots of bottom from them.

[4 Strings]

[quote name='ShergoldSnickers' date='Jul 29 2010, 09:29 AM' post='908920']
"... everything full on for half an hour. Eventually the aluminium dome shattered!"


Mix loud then?

[4 Strings]

[quote name='Mr. Foxen' post='909067' date='Jul 29 2010, 11:49 AM']There was an email exchange with one of the Celestion engineers about speaker break in on some other forum, he said the sound of a Vintage 30 does change but it is supposed to sound right from the box, so the bottomier tone after they are played in (favoured for Doom) is actually the sound of a worn out driver. It is fairly noticeable with guitar drivers when you are expecting lots of bottom from them.[/quote]


Worn out? Didn't know they wore, no moving parts touch, if the coil or suspension goes, it goes.

[Al Heeley]

[quote name='ShergoldSnickers' post='908920' date='Jul 29 2010, 09:29 AM']Declaration: This is not scientific - merely experience on my part

I've gone through several pairs of hi-fi loudpeakers, the latest of which I still have after nearly 20 years, a pair of Epos ES14s, originally bought as monitoring for a recording studio. I bought these after a protracted audition at a colleagues house, but when I got my new pair home, was surprised at how bass light they sounded....

...A few years later.... the glue on one of the drivers went, around where the coil former meets the cone. I Put the spare bass/mid driver in and instantly got the bass light sound on this cabinet only. It went after a day or so. It could be psychoacoustics, but the difference was marked, and on balance I'd plump for the driver rather than perception, but can't absolutely prove either one over the other.[/quote]
What does this illustrate? That the original drivers had got bassier over time or that the new driver you installed had a different frequency response?
Is it breaking in/wearing out or is it inconsistencies within production units?

Were there any orange drop spragues involved at any point? We seem to have nerded off-topic but in an entertaining, convivial and light hearted way.

[escholl]

[quote name='4 Strings' post='909162' date='Jul 29 2010, 12:55 PM']Worn out? Didn't know they wore, no moving parts touch, if the coil or suspension goes, it goes.[/quote]

+1

[LawrenceH]

Subject successfully derailed.

Psychoacoustic phenomena explaining break-in would be more believable in cases where you listen to the speaker for extended periods, hence in audio mixing/mastering where you take breaks every so often, A/B with other commercial mixes, etc. to compensate for your ears adjusting - I'm well-used to that!
I did not listen to the speaker for an extended period, just heard it once when freshly installed and once again a day later after it had been left with a LF signal running through it. The difference was, as I said, very obvious with the initial sound being distorted and extremely bass-shy. As much as I trust my ears to discriminate between a £100 versus £1000 PA speaker, I trust the difference I heard to be real. But I'm sure it varies considerably from driver to driver, depending on construction, materials etc. Hence it could be negligible in many cases, especially lower power drivers as opposed to big PA drivers with quite heavy-duty suspension. I must say I'd never noticed it with other drivers but then I've only built PA speakers before rather than dedicated bass cabs. What drivers does the AES paper relate to?

Mechanically, get a piece of paper, fold it, and bend it back and forth a few times. It changes, and though that happens fast, that's with a more extreme degree of flex than a rolled loudspeaker edge would be subject to.

I understand when people question other people's ears over subtle differences, it's definitely good to hear things for yourself. 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.

[stevie]

[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.

[LawrenceH]

In fact I found the original exchange you had with Alex on this, interesting that he's also talking about an Eminence and his description of what he hears and how obvious it is tallies well with my own aural 'observation'. He reckons there's a big difference between hi-fi speaker surrounds and PA drivers. He's not one to buy into
I'd happily do some measurements if someone provides me with a boxed new Eminence driver and £30 for my trouble! But, I trust my ears more than I'd trust the rubbish testing conditions/aparatus I'd have to use...bass measurements can be a bit haphazard unless you have a decent set-up.

[LawrenceH]

[quote name='stevie' post='909455' date='Jul 29 2010, 05:05 PM']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]

Hmm, good point. I was more trying to say I don't think my ears are especially golden! As opposed to where people boast about how great they are, or try to justify some ridiculous expense as a protection mechanism.
I guess I mean that there is a real-world cut-off between what's one of those things where you can convince yourself you can hear something or other, and when something plainly sounds rotten and awful, otherwise we'd all be playing through banks of Chinese ipod speaker docks. Burden of proof often works both way before accusations are made.

[escholl]

[quote name='LawrenceH' post='909456' date='Jul 29 2010, 05:06 PM']>"what he hears"

>"my own aural 'observation'."

>"He reckons"

>"I trust my ears more than I'd trust the rubbish testing conditions/aparatus"[/quote]

Your ears can be surprisingly good liars. You hear what you expect to hear. If you have any friends who are music producers or mixing engineers, ask them if they've ever accidentally used an EQ which, in fact, wasn't connected or engaged -- but they didn't realise till after they'd "gotten" the sound the wanted. It's happened to me, it's happened to a few people I know -- you feel silly, but it demonstrates to what extent you can hear what you expect to hear.

This is why you need to measure, and not trust your ears. Notice how speakers never sound worse when they're broken in? If speaker break in was a "thing" there is no way that would be true in every instance.

I listen to the same speakers everyday. Usually a lot of the same music too. Sometimes, they sound a lot different than they did the day before -- have they changed? Well, they're 37 years old, so I'd say they're probably broken in by now.

[stevie]

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.

[ShergoldSnickers]

[quote name='ShergoldSnickers' post='908920' date='Jul 29 2010, 09:29 AM']"... everything full on for half an hour. Eventually the aluminium dome shattered!"


Mix loud then?[/quote]
Not usually no...

This was a request from the driver designer - to push the treble unit to breaking point. He wanted to show us how robust they were. After trying normal music through the driver, we realised we would have to devise a drum machine from hell loop that pushed every hi-hat and cymbal sound we could muster, and as loud as the drum machine, pre-amp and power amp could push out. That test was a lot of fun - not often that you are asked to deliberately try and break something.

We had to stay in the control room and test the driver in the main recording area. Painfully loud.

[ShergoldSnickers]

[quote name='Al Heeley' post='909178' date='Jul 29 2010, 01:05 PM']What does this illustrate? That the original drivers had got bassier over time or that the new driver you installed had a different frequency response?
Is it breaking in/wearing out or is it inconsistencies within production units?

Were there any orange drop spragues involved at any point? We seem to have nerded off-topic but in an entertaining, convivial and light hearted way.[/quote]
All great points of course, and as I said - my experience was utterly unscientific The change in the newly installed driver from bass light to 'correct' inside 24 hours, suggests a mechanical phenomena. [b]IF[/b] I can trust my ears.

Trying desperately to swerve back to the topic (and failing miserably), the only capacitance involvement was the single capacitor crossover used in the speakers, which we bypassed when testing the treble driver to destruction. The bass-mid was designed to deliberately roll off mechanically and blend with the treble driver characteristics. As the designer designed and made both units to suit, the end result was a neat way of avoiding more complex crossover designs to match drivers that couldn't be mechanically tweaked if bought off the shelf. Interesting approach.

I'll start a separate topic if I find anything else to say.

[stevie]

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.

[LawrenceH]

[quote name='escholl' post='909476' date='Jul 29 2010, 05:26 PM']Your ears can be surprisingly good liars. You hear what you expect to hear. If you have any friends who are music producers or mixing engineers, ask them if they've ever accidentally used an EQ which, in fact, wasn't connected or engaged -- but they didn't realise till after they'd "gotten" the sound the wanted. It's happened to me, it's happened to a few people I know -- you feel silly, but it demonstrates to what extent you can hear what you expect to hear.

This is why you need to measure, and not trust your ears. Notice how speakers never sound worse when they're broken in? If speaker break in was a "thing" there is no way that would be true in every instance.[/quote]

Yes, yes, BUT. This was not one of those times! Like I said the difference was night and day, like comparing a full PA speaker with an overloaded ipod docking station. We did measure at the time, using a crude Behringer RTA, and it supported what we heard (but as I say I don't completely trust the kit/set-up we had). We had to boost the bass massively to get a decent balance. Then the next day we ran it flat to start with and the bass was hitting the chest nicely (still didn't sound good overall, but that's another story. Anyone want to buy a BFM Jack 10? ).

Sometimes though you do have to trust your ears, like when you buy kit, you never go purely on spec. After all, I don't listen to music by looking at oscilloscopes and RTAs. For sure there is variation in our hearing from day to day, even moment to moment, and it can be surprising how they're fooled, but after a while you get a good feel for what's accounted for by that and what isn't and I've done enough mixing to know where my normal limits are. This was definitely outside them, the same way I can tell the difference between a 1k and 5k test tone completely robustly! Doesn't even mean what I'm hearing as the low octave is real bass, or something elsewhere, just that I'm confident I heard a genuine (marked) difference that I could have picked out in a blind test.

Interesting that Stevie's graphs show reasonably substantial spec variation between the driver before and after, but because of the way the parameters alter in that particular box/driver combo it models out the same. Doesn't mean they always will, of course (I wonder if the fact that we were using a horn-loaded design would have any bearing there?). I expect Stevie's going to say the driver was run in in about 30 seconds!

[escholl]

[quote name='stevie' post='909493' date='Jul 29 2010, 05:55 PM']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]

This is very interesting actually, 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?

Rms has lowered, indicating the suspension's mechanical resistance has dropped slightly, however Vas and Mms have gone up (to approximately the published specs), while Cms has also dropped. Fs has dropped as a result, which is intriguing, however when comparing to Eminence's published specs I would be interested to know what the margin of error was for this experiment.

Qes has also dropped, indicating the speaker is better damped electrically than it was initially. Also, f3 has dropped by 12 Hertz for an identical enclosure. At this rate, it looks like I could well be wrong on this occasion! But I'd like to know more about exactly what you've done.

[Phil Starr]

[quote name='stevie' post='909493' date='Jul 29 2010, 05:55 PM']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]
Love the thread and this is interesting data. The figures show the sort of increase in compliance you would expect after a breaking in period though why Qes would change beats me.

The cone and surround of high power speakers are usually made of plant fibres (in turn made of lignin and hemicelluloses) and this is normally treated with some sort of latex or plastic. The spider is usually some sort of treated woven cloth. The fibres vary in their strength and some will break when subjected to repeated vibrations. The weaker ones will break early on and the process will continue throughout the life of the speaker until the surround (usually) fails. In addition you would expect there to be gradual chemical changes in the polymers used. All this means that there will be gradual changes in the mechanical characteristics of both the suspension and cone of the speaker throughout its life. This will be most rapid early in the life of the speaker which is what causes the breaking in period.

I've noticed that the impedance/frequency curve of a speaker changes over time to the extent that I won't tune a reflex port until a speaker has had a period of use and you can definitely hear the changes in response.

[stevie]

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.

[Al Heeley]

what i dont understand is the significance of any difference in the figures, are you saying this shows an audible difference in terms of tonal response or can the differences only be picked up by the measuring equipment?
If there is a margin of measurement error, is it bigger or smaller than any margin of difference you could expect to see between identical units for same mfr?
This goes right back to the Capacitor issue, can differences be heard or only measured?

Edited July 30, 2010 by Al Heeley

[thepurpleblob]

Just to return to the OP's question. Probably no difference at all.

You have to keep it in perspective - the tone control on a Fender bass is the most basic thing known to man - a simple first order resistor-capacitor filter. The thing is inherently a bit useless to start with so the type of cap is going to make very little difference. I'm not sure why they bothered. I would just do without it and use the (almost certainly) much more useful eq on your preamp.

Similarly you can't hear the difference between different types of pot. It's just a resistor. If you can hear a difference then one is broken and needs replaced.

BTW... the length of the cable you use to plug a passive bass into the amp probably makes more difference as that introduces an unknown amount of capacitance itself which modifies the signal somewhat.

Edited July 30, 2010 by thepurpleblob