Which Ceramic 12" driver?

[Mr. Foxen]

[quote name='Phil Starr' timestamp='1360371364' post='1969665']
Just off to bed but OK then. I'm not sure what sort of sound a Berg makes so if you find me a link to a good recording or you or someone else can describe it I'll be able to get close. If you can find a frequency plot that will be perfect.

In the meantime there's a 12" speaker that is a real gem for bass that I actually use when I'm not DI'ing, the Beyma SM212.
[url="http://www.bluearan.co.uk/index.php?id=BMASM212&browsemode=manufacturer"]http://www.bluearan....de=manufacturer[/url]
[url="http://profesional.beyma.com/pdf/SM-212E.pdf"]http://profesional.b...pdf/SM-212E.pdf[/url]

Why would I go for this? well Xmax is conservatively 7mm, tht's how far the cone will travel without distorting. This means that you won't lose output because the coil has left the magnet gap at high power.

2. there's good output up to 5,000Hz so there's plenty of top end there without a tweeter. This is done without a huge peak in output at 1-2kHz that a lot of the Eminence designs display. (not necessarily bad but it does colour the sound.)

3. Fs is lowish so you'll cover fundamental bass down to 40Hz

4. Qts is 0.38 which makes it relatively easy to tailor the bass to give a flat response.

5. It is nicely made with a cast chassis, sensitivity is OK too

The only problem is that for a 12 it does need a fair size box ideally. The sound with bass is pretty open and clean sounding, you hear the strings coming through nicely. Bass is clean and deep without being boomy, just well controlled. Because of the excellent top end response you hear lots of detail too but without the Eminence cone break up the speaker doesn't add too much character of its own. I'll talk you through the Eminence and Fane ranges and try and predict strengths and weaknesses for you tomorrow. I've used both quite a lot but nothing matches the Beyma at this price point at the moment IMO
[/quote]

Out of stock mind. Not spotting them anywhere else with half arsed effort.

[Musky]

[quote name='Phil Starr' timestamp='1360371364' post='1969665']

The only problem is that for a 12 it does need a fair size box ideally.
[/quote]
I'm certainly no expert, but doesn't stuffing a speaker into a smaller than ideal box create a hump in the low mids - which seems to be what the OP is looking for?

[Phil Starr]

[quote name='Mr. Foxen' timestamp='1360376186' post='1969684']
Out of stock mind. Not spotting them anywhere else with half arsed effort.
[/quote]

Ah, I forgot to mention the other problem, Blue Aran order these from Spain and they take ages to arrive.

[quote name='Musky' timestamp='1360395397' post='1969712']
I'm certainly no expert, but doesn't stuffing a speaker into a smaller than ideal box create a hump in the low mids - which seems to be what the OP is looking for?
[/quote]

If that is what he is looking for then yes it will create a hump. Just needed to mention that when designing the cab it is one extra constraint. Mainly I wanted to give an idea of how to look at T/S parameters in choosing a speaker. Qts of around 0.4 gives you a chance of a flat bass response but Vas of 150l means a bigger cab. My speakers are in a considerably undersized cab which, sure enough, gives the hump you mention.

[Balcro]

These people may be your best bet -

http://www.lmcaudio.co.uk/acatalog/LMC_Web_Catalogue_12__Drivers_53.html?oo=0

- they're Beyma's UK distributor. Price looks the same as Blue Aran.

Balcro

[Bill Fitzmaurice]

[quote name='Musky' timestamp='1360395397' post='1969712']
I'm certainly no expert, but doesn't stuffing a speaker into a smaller than ideal box create a hump in the low mids[/quote]In the midbass, actually, and that's what's responsible for boom. If you've got a cab that booms chances are the box is too small for the drivers. But the box size doesn't depend on the driver size alone, it depends on all the spces.[quote]- which seems to be what the OP is looking for?
[/quote]One can't say. If the intent is to sound like a Berg one first has to quantify what that means. Since Berg doesn't post frequency response charts you'd have to measure one yourself, or find someone else who has done so. Then you can use modeling to match up the low frequency response and driver data sheets to match up the midrange and high frequency response. But without doing all that attempts to get a Berg tone, or any specic result, via sticking a random driver into a box will be as effective as tossing darts...blindfolded.

[6v6]

[quote name='Phil Starr' timestamp='1360371364' post='1969665']
Just off to bed but OK then. I'm not sure what sort of sound a Berg makes so if you find me a link to a good recording or you or someone else can describe it I'll be able to get close. If you can find a frequency plot that will be perfect.

In the meantime there's a 12" speaker that is a real gem for bass that I actually use when I'm not DI'ing, the Beyma SM212.
[url="http://www.bluearan.co.uk/index.php?id=BMASM212&browsemode=manufacturer"]http://www.bluearan....de=manufacturer[/url]
[url="http://profesional.beyma.com/pdf/SM-212E.pdf"]http://profesional.b...pdf/SM-212E.pdf[/url]

Why would I go for this? well Xmax is conservatively 7mm, tht's how far the cone will travel without distorting. This means that you won't lose output because the coil has left the magnet gap at high power.

2. there's good output up to 5,000Hz so there's plenty of top end there without a tweeter. This is done without a huge peak in output at 1-2kHz that a lot of the Eminence designs display. (not necessarily bad but it does colour the sound.)

3. Fs is lowish so you'll cover fundamental bass down to 40Hz

4. Qts is 0.38 which makes it relatively easy to tailor the bass to give a flat response.

5. It is nicely made with a cast chassis, sensitivity is OK too

The only problem is that for a 12 it does need a fair size box ideally. The sound with bass is pretty open and clean sounding, you hear the strings coming through nicely. Bass is clean and deep without being boomy, just well controlled. Because of the excellent top end response you hear lots of detail too but without the Eminence cone break up the speaker doesn't add too much character of its own. I'll talk you through the Eminence and Fane ranges and try and predict strengths and weaknesses for you tomorrow. I've used both quite a lot but nothing matches the Beyma at this price point at the moment IMO
[/quote]

Thank you very much for the recommendation (and for answering my original question and sharing your knowledge without treating me like an idiot )

I've downloaded winisd pro, have loaded the driver data and am now going to start getting to grips with how to model the enclosure. Good learning experience!

[Mr. Foxen]

Bear in mind that WinISD is good for up to 200hz, the rest is up to the chart, and lining the box right and such.

[Phil Starr]

OK I said I'd look at choosing a driver. Now I have to be honest and say I don't know exactly what a driver is going to sound like from a spec sheet alone. However having an understanding of the specs and a bit of experience gets me 80% there. A very simple approach will rule out the real duds and that is what I'll try to explain. I'm not going to use algebra but to really get any deep understanding you'll need to get to grips with it or trust the computer to do it for you. Basically if you know how heavy a cone is, how stiff its suspension is and how much air it is pushing against and add in the springiness and mass of air in the box you can work out how far the cone moves for a given force at a given frequency. If you know all about the magnet and the coil you can work out the force so for each frequency you can work out the sound level. If you get it right the box volumes and the speaker match up, called an alignment, and the output is more or less the same at all frequencies. (the engineers and scientists are probably going to shoot me down for over simplifying here )

OK to choose the speakers I'm going to look at four parameters only, Vas which roughly says how hard it is to move the speaker cone Qts which is all the mechanical and electromagnetic factors lumped together, Fs is the resonant frequency and says how low the speaker will go and Xmax which is how far the cone can move before the coil leaves the magnet and is the true measure of how much power the speaker can handle.

Now the speakers I am going to look at are the Eminence Alpha, Beta, Delta and Kappa (what happened to Gamma?)

Alpha fs-49Hz Qts 0.77 Vas 121.5 Xmax 2.4mm
Beta 47 0.46 120.1 4.4
Delta 55 0.43 81.3 2.4
Kappa 45 0.27 112 3.2

All the specs are here http://www.eminence.com/pro-audio/american-standard/?size=12#speakers you need to download the PDF's

Now you could just plug the data into win ISD or do the sums but if you can find an alignment chart, I haven't been able to find one on the internet but most books on speaker design have them. Basically for each value of Qts there is a fixed ratio between box size and cut off frequency. Low Q means a smaller box and a higher cut off frequency. Q of about 0.4 is ideal for reflex enclosures.

So the alpha has Q=0.77 which is too high because it has a titchy magnet. this means the box needs to be roughly 3x Vas (360l 0r 12 cu ft) for the best response which still has a huge bass hump of over 6dB. You can put it into a smaller box but you are going to make the bass hump even bigger. This speaker just isn't suitable for a reflex design and the magnet is too small to even make a decent sealed cab really. It's a dud.

The Beta has been redesigned recently. Q is ).46 which my table says means box size is Vas/1.03 or 120l which is big but practicable. The bass peak is 1dB which you will just notice. The cut of frequency is fs/0.97 or 46Hz which is OK too. Put it in a smaller box and you will get a bigger bass hump and cut off will rise a little but this speaker works for me.

The Delta is a missed opportunity for me. They've added a bigger magnet but stiffened the suspension. this has raised Fs to 55Hz. The lower Vas and Q means the box size comes out at 70l with a bass hump of 0.5 dB which yoiu won't notice. The big problem though is Xmax of 2.4mm, this means the coil will move out of the magnet at relatively low powers and the speaker start to distort with any real bass.

The kappa has a huge magnet, Q is now 0.27 and my design table says to divide Vas by 3.17 to get box size or 35l. the big magnet means a compact box. Unfortunately making Q so much lower than 0.4 raises the cutoff frequency which is Fs x 2.15 or 97Hz. This is too high for a bass cab where bottom E is 41Hz.. Xmax is 3.2mm which is still fairly poor. This is a speaker which would be much improved by having a longer voice coil and different geometry giving a better Xmax and a better bass performance at the expense of sensitivity.

So I've surprised myself by coming down in favour of the Beta, the best of this group though it needs a fairly generous cab and will still have a warm and woolly bass hump. I might put the Deltas into winISD if I was bored but the other two are not worth looking at. I wouldn't buy any of these.

So far I've only looked at bass response but that alone has narrowed the search. If Qts is outside of 0.3-0.5 fs is over 50Hz or Xmax less than 4mm I won't look any further because I am unlikely to be able to engineer a decent cab. If Vas is too big then the cab will have to be correspondingly large so that's a side issue too.

[JTUK]

Good post, Phil Starr.


I think the point with all the choices is that nothing is for nothing.
If you go for one set of attributes over and above what the chasis will give, you will have to trade for another set.
Sometimes you might make the cab build too complicated and ultimately flawed ...it all depends if you can live with your 'flaws'..??

[6v6]

[quote name='Phil Starr' timestamp='1360580306' post='1972501']
OK I said I'd look at choosing a driver. Now I have to be honest and say I don't know exactly what a driver is going to sound like from a spec sheet alone. However having an understanding of the specs and a bit of experience gets me 80% there. A very simple approach will rule out the real duds and that is what I'll try to explain. I'm not going to use algebra but to really get any deep understanding you'll need to get to grips with it or trust the computer to do it for you. Basically if you know how heavy a cone is, how stiff its suspension is and how much air it is pushing against and add in the springiness and mass of air in the box you can work out how far the cone moves for a given force at a given frequency. If you know all about the magnet and the coil you can work out the force so for each frequency you can work out the sound level. If you get it right the box volumes and the speaker match up, called an alignment, and the output is more or less the same at all frequencies. (the engineers and scientists are probably going to shoot me down for over simplifying here )
[/quote]

Ok, thanks for the clear, simple explanation - I'm not afraid to do a bit of maths and/or experiment with the computer

[quote name='Phil Starr' timestamp='1360580306' post='1972501']
OK to choose the speakers I'm going to look at four parameters only, Vas which roughly says how hard it is to move the speaker cone Qts which is all the mechanical and electromagnetic factors lumped together, Fs is the resonant frequency and says how low the speaker will go and Xmax which is how far the cone can move before the coil leaves the magnet and is the true measure of how much power the speaker can handle.

Now the speakers I am going to look at are the Eminence Alpha, Beta, Delta and Kappa (what happened to Gamma?)

Alpha fs-49Hz Qts 0.77 Vas 121.5 Xmax 2.4mm
Beta 47 0.46 120.1 4.4
Delta 55 0.43 81.3 2.4
Kappa 45 0.27 112 3.2

All the specs are here [url="http://www.eminence.com/pro-audio/american-standard/?size=12#speakers"]http://www.eminence....ize=12#speakers[/url] you need to download the PDF's

Now you could just plug the data into win ISD or do the sums but if you can find an alignment chart, I haven't been able to find one on the internet but most books on speaker design have them. Basically for each value of Qts there is a fixed ratio between box size and cut off frequency. Low Q means a smaller box and a higher cut off frequency. Q of about 0.4 is ideal for reflex enclosures.
[/quote]

Aha! You reminded me that I have an old book on speaker design (ancient book from Tandy/Radio-Shack which I got back in the 90's!) it has tables as you describe, although they are a bit small so probably not that accurate.

[quote name='Phil Starr' timestamp='1360580306' post='1972501']
So the alpha has Q=0.77 which is too high because it has a titchy magnet. this means the box needs to be roughly 3x Vas (360l 0r 12 cu ft) for the best response which still has a huge bass hump of over 6dB. You can put it into a smaller box but you are going to make the bass hump even bigger. This speaker just isn't suitable for a reflex design and the magnet is too small to even make a decent sealed cab really. It's a dud.

The Beta has been redesigned recently. Q is ).46 which my table says means box size is Vas/1.03 or 120l which is big but practicable. The bass peak is 1dB which you will just notice. The cut of frequency is fs/0.97 or 46Hz which is OK too. Put it in a smaller box and you will get a bigger bass hump and cut off will rise a little but this speaker works for me.

The Delta is a missed opportunity for me. They've added a bigger magnet but stiffened the suspension. this has raised Fs to 55Hz. The lower Vas and Q means the box size comes out at 70l with a bass hump of 0.5 dB which yoiu won't notice. The big problem though is Xmax of 2.4mm, this means the coil will move out of the magnet at relatively low powers and the speaker start to distort with any real bass.

The kappa has a huge magnet, Q is now 0.27 and my design table says to divide Vas by 3.17 to get box size or 35l. the big magnet means a compact box. Unfortunately making Q so much lower than 0.4 raises the cutoff frequency which is Fs x 2.15 or 97Hz. This is too high for a bass cab where bottom E is 41Hz.. Xmax is 3.2mm which is still fairly poor. This is a speaker which would be much improved by having a longer voice coil and different geometry giving a better Xmax and a better bass performance at the expense of sensitivity.

So I've surprised myself by coming down in favour of the Beta, the best of this group though it needs a fairly generous cab and will still have a warm and woolly bass hump. I might put the Deltas into winISD if I was bored but the other two are not worth looking at. I wouldn't buy any of these.

So far I've only looked at bass response but that alone has narrowed the search. If Qts is outside of 0.3-0.5 fs is over 50Hz or Xmax less than 4mm I won't look any further because I am unlikely to be able to engineer a decent cab. If Vas is too big then the cab will have to be correspondingly large so that's a side issue too.
[/quote]

Ok, great, that worked example really helps a lot - thank you for taking the time to write that up, much appreciated!

So going back to the Beyma SM212 which you mentioned earlier, which has a Qts of 0.25, and a Vas of 198l according to the datasheet, perhaps I can work through the same calculations to make sure I have this right:

Charts give a volume multiplier for Qts of 0.25 of about 0.3 according to my small/inacurate graphs, so box size should be around (198*0.3)==59.4, so a box of about 60L should be OK?

Then the next graph is tuning frequency factor, which gives me about 1.3 for Qts of 0.25, so that gives a cutoff frequency of (fs*1.3), and fs is 34Hz, giving a cutoff frequency of about 44Hz?

So does that mean using the SM212 will make the fundamental of my low-E (I play 4 string only) 3dB down, or am I misunderstanding the meaning of the cutoff frequency?

Thanks again for your help working through this!

[Phil Starr]

Hi I have different figures for the SM212 Vas 150 and Qts 0.38.

Cut off frequency is a bit of a misnomer it is just the point where the output is down 3dB it will go on producing sound below this point. At this point i'd use winISD so you can model the output more accurately. Generally lowQ speakers 'cutoff' at a higher frequency but keep producing sound quite low whereas highQ speakers like the Alpha will cut off lower but very sharply. WinISD will show you this, It has the parameters for most Eminence speakers in already so you can mess about with changing things like box size without needing to enter data for these speakers.

As anyone who uses an Ampeg 8x10 can tell you a speaker that doesn't go down to 40Hz can still sound quite bassy. Most of what we hear are the harmonics not the fundamentals.

[6v6]

[quote name='Phil Starr' timestamp='1360597281' post='1973021']
Hi I have different figures for the SM212 Vas 150 and Qts 0.38.
[/quote]

Ah, I downloaded the pdf datasheet from here:
http://www.europe-audio.com/Product.asp?Product_ID=3627

It looks like there are two models, the SM212 and the SM212E, I got the datasheet for the former by the looks of it - confusing!

[quote name='Phil Starr' timestamp='1360597281' post='1973021']
Cut off frequency is a bit of a misnomer it is just the point where the output is down 3dB it will go on producing sound below this point. At this point i'd use winISD so you can model the output more accurately. Generally lowQ speakers 'cutoff' at a higher frequency but keep producing sound quite low whereas highQ speakers like the Alpha will cut off lower but very sharply. WinISD will show you this, It has the parameters for most Eminence speakers in already so you can mess about with changing things like box size without needing to enter data for these speakers.

As anyone who uses an Ampeg 8x10 can tell you a speaker that doesn't go down to 40Hz can still sound quite bassy. Most of what we hear are the harmonics not the fundamentals.
[/quote]

Ok, thanks - I'll have a look in WinISD later!

[Mr. Foxen]

Get Winisd pro alpha, rather than the beta non pro, it does more stuff. Seems people go for the beta one when they first get it for whatever reason and it doesn't work quite the same as the one everyone else is using.

[Phil Starr]

Hi again, I'm not sure about that data sheet, it does say preliminary data sheet though it also looks like it cae from Beyma. I really don't think a magnet of that size could give a Q that low, go with the figures in the link I gave you, which did come off beyma's site and which did work when I built the cab.

[stevie]

Beyma changed the spec of that driver in 2006. It looks like the only thing they did was to fit a stiffer suspension: the coil and cone look the same. There will some difference around the bottom rolloff point, but not much. Phil's spec is the current one.

[stevie]

[quote name='Phil Starr' timestamp='1360580306' post='1972501']
The Beta has been redesigned recently. Q is ).46 which my table says means box size is Vas/1.03 or 120l which is big but practicable. The bass peak is 1dB which you will just notice. The cut of frequency is fs/0.97 or 46Hz which is OK too. Put it in a smaller box and you will get a bigger bass hump and cut off will rise a little but this speaker works for me.
[/quote]

Another important criterion when choosing a driver for bass guitar is its frequency response. Good bass guitar drivers have a frequency response that extends smoothly up to and beyond 2 or 3kHz. This makes a difference to the clarity of "tone", even though the driver rolls off much earlier than this off axis. You should avoid drivers that have large peaks in the frequency response because this is a result of undamped resonances and distortion - although not usually a problem if you are going to cross over to a midrange driver and less of a problem if you use a smaller driver on top.

The Beta 12 is the only 12-incher in the Eminence range of ceramic drivers that has a decent frequency response in the midrange (as far as I know). I fitted one to a PA speaker last week and put my bass through it. It sounded all right (the JBL compression driver helped but the plastic cabinet didn't). It was in a 45-litre cab and I didn't measure any bass hump at all.

I'm surprised that the Celestion bass guitar range gets so little attention on here - especially as these are specifically designed for bass guitar. I've used the 300-watt green neos and they were good. The ceramic BL12-200X is under £50 and would be my first choice for a budget bass guitar 12-inch driver. Phil's Beyma certainly looks the business though.

[Phil Starr]

Stevie is right about the frequency response. Most of what we hear is midrange so that bass response is actually less important to the overall sound. What I've done so far is trawl through a few speakers to see if they will do the job. If Xmax is too small you will struggle to get good clean bass at decent sound levels. If the magnet is too small then it is likely to mean the cabinet will be too big to be practicable and so on. The next thing is very definitely to look at frequency response which gives you some idea of how it is likely to sound in a cab.

I didn't mean to exclude the Celestions but there are a couple of things that concern me Xmax is low though confusingly they use a different measure to Eminence who are more generous in what they quote. Some of the Celestions also have a high cut off point when put in a cab but I've never modelled the 12's, just the 10's. I'll have a look at the Celestions tomorrow.

Stevie is pretty knowledgeable about these things, he caught me out in my formulae on BC once I try to be accurate but the more you can learn for yourself the better.

[stevie]

Phil, the reason I mentioned frequency response is that I've never seen it discussed on here before.

I just wanted to put a word in for the Celestions because everyone on BC seems to automatically favour Eminence, whose products really are a very mixed bunch. In a typical 12-inch cab the green Celestions (the BL-200X ceramic and BN-300X neo) model exactly the same as the Beyma at the bottom end (and the Eminence Beta 12 in fact). So they're going to have a full, warm bass sound.

I've never seen the point of the Orange series because 1. their xmax is limited, as you rightly point out, and 2. because they roll off early when you load them in a box and will sound quite thin (very similar to the Eminence 3012HO which is not an ideal bass guitar speaker despite Mr Foxen's eulogy). However, they may work better in practice than expected - and I've never used them personally.

The Green Celestions have an xmax of 4mm. As this is a proper voice coil overhang it's probably equivalent to 6.5mm on an Eminence and is perfectly acceptable, although not in the same league as the Beyma it must be said.

[Phil Starr]

Hi Stevie I've looked at the Celestion and I agree it looks like a perfectly decent speaker, [url="http://celestion.com/product/39/bl12200x/"]http://celestion.com...ct/39/bl12200x/[/url] Like you I do wonder why they make the orange label drivers.

The only reason I tend to refer to Eminence speakers a lot is they have probably the clearest data sheets, they produce a wide range of drivers and because their design philosophy seems to be stick any coil on a cone with all the magnet sizes they have lots of examples of poorly thought out speakers.

I'll try and write something for 6v6 on frequency responses soon.

[Mr. Foxen]

[quote name='stevie' timestamp='1361013807' post='1979721']
the Eminence 3012HO which is not an ideal bass guitar speaker despite Mr Foxen's eulogy). However, they may work better in practice than expected - and I've never used them personally.
[/quote]

Have heard them, sound awesome.

[6v6]

Ok, thanks very much for the help guys

Point taken about the frequency response - I think the sound I'm going for can probably be described as punchy/smooth/fat/round, so I can see that avoiding anything which will give big peaks (particularly in the high mids) is going to help achieve this goal and make the cabinet more versatile.

I also do not want a bright sounding cabinet - I play with flats, do not slap, and my band plays mostly folk/blues/rock, so I'm probably not going to fit a tweeter, so if a driver has reasonable smooth frequency response into the highs that's definitely a good thing (IIRC Phil Starr mentioned this a characteristic of the SM212)

I also don't understand why Celestion bass speakers are unpopular - a good friend of mine has a 2x10 cab fitted with the (green-label) BL10-200X drivers and it sounds great IMO.

That said, I've decided to go with Phil Starr's recommendation on the Beyma SM212, it seems to tick all the boxes and I've not heard a Beyma speaker before, so it should be an interesting experiment

I've started experimenting with WinISD pro alpha, but have hit a problem adding the driver data for the SM212 - it's not part of the supplied database, and whenever I try adding the data manually it throws up consistency check errors when trying to save the driver model.

I've tried several times, following the help-page which explains the parameters to enter and those which should be calculated - so far without success, my guess is there's a minor rounding error on one of the parameters on the datasheet, but I'm not sure which one?!

Does anyone (Phil Starr?) have a wdr file for the SM212 they can share which will work with WinISD pro alpha?

[VTypeV4]

6V6, When you're inputting the data for the speaker make sure you've got the correct parameter value/scaling. For example Vas can be measured in Litres, Cubic Cm, Cubic M, Cubic inches or Cubic Feet.

I've never used WinISD but I've put data into Eminence designer before and it's thrown up errors becuase I didn't check..

Hope that helps..

[6v6]

[quote name='VTypeV4' timestamp='1361096744' post='1980881']
6V6, When you're inputting the data for the speaker make sure you've got the correct parameter value/scaling. For example Vas can be measured in Litres, Cubic Cm, Cubic M, Cubic inches or Cubic Feet.

I've never used WinISD but I've put data into Eminence designer before and it's thrown up errors becuase I didn't check..

Hope that helps..
[/quote]

Thanks, I've checked and double checked and I do think I have all the units right - problem is WinISD doesn't report the validation failure very helpfully, i.e it doesn't clearly identify what criteria caused the check to fail, it just gives you a long list of parameters which it has failed to validate.

I'll try again later, but if anyone can help me out with a driver profile which works it will save me some swearing!

[stevie]

The Beyma is a great choice. Here are the parameters, which have been cross-calculated and shouldn't throw up any errors.

I'd pick the size of box you want rather than letting WinISD do it for you. 50-litres would be a good starting point. Tune between 50 and 55Hz using (preferably) a single 100mm dia. or else 2 x 70mm ports.

[IMG]http://i48.tinypic.com/n1rpmo.jpg[/IMG]

[Balcro]

[quote name='6v6' timestamp='1361098337' post='1980918']
Thanks, I've checked and double checked and I do think I have all the units right - problem is WinISD doesn't report the validation failure very helpfully, i.e it doesn't clearly identify what criteria caused the check to fail, it just gives you a long list of parameters which it has failed to validate.

I'll try again later, but if anyone can help me out with a driver profile which works it will save me some swearing! :lol:
[/quote]

It's easy to make a mistake when copying data into winISD. Different manufacturers show data in different units. The two I've found easiest to confuse are the figures for "Cms" and "Sd". Beyma use micrometer/newtons for Cms while most others manufacturers use mm/newtons.
Likewise with "Sd", Beyma uses numbers in Metres Squared while other manufacturers and winISD demand the unit in Square centimetres. So just watch your units. It's easy to end up with a fundamental resonance of 1850!!!

Enter the basic data as per the help file. Perhaps the first 5 paramenters, Qes, Qms, Vas, Mms and Cms - wait - allow a few seconds for winISD to do its work in the background and it will start to produce data in the calculation fields (blue text). Enter the more universal data like "Z" (8 Ohms) for the impedance and the power rating "Pe" - 350 watts. Try saving data. If the dialogue panel shows up those irritating errors, go back & delete the last item of entered data such as BL, for example. Wait again. winISD will recalaculate in the background. Try saving again. When you don't have the errors, then save your data. You can always recall the saved data and enter more at a later time.
It's always best to let winISD do the calculations, but don't be surprised if the "Fs" or some other parameter differs from the manufacturers by (in this case 0.56 HZ).

Good luck,

Balcro

Edited February 17, 2013 by Balcro