lemmywinks Posted March 27, 2011 Share Posted March 27, 2011 (edited) Hi I'm going to get down to constructing another mini lightweight cab as the weather is getting a bit warmer and could do with a little bit of help. The driver i am using is a Celestion BN10-300s, the 4ohms version. I have got most of the specs for use in WinISD but have a few questions: - What is the Z value? [size=1][b]EDIT - Ohmage?[/b][/size] - How do i find the SPL and Z? I understand that SPL at least is pretty essential for modelling bass drivers and they both feature on the frequency/impedance graph, but how do i find the actual values to input into WinISD? Also: - What are the Pe and Sd? [size=1][b]EDIT - Is Pe the power rating (w)? Still can't find Sd though[/b][/size] - Is the "diameter" the voice coil or driver diameter? [size=1][b]EDIT - I assmue the driver?[/b][/size] I also understand that Celestion don't use the same methods to get the specs for their drivers, so their values aren't comparable to other drivers. I assume this will be a problem when trying to model the cab? Cheers! Steve Edited March 27, 2011 by lemmywinks Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted March 27, 2011 Share Posted March 27, 2011 (edited) WinISD calculates a lot of values automatically, derived from the others e g Sd is derived from D which is provided on the Celestion spec sheet. Input too many and they often won't tally with the calculated values (due to e.g. rounding errors) and WinISD will refuse to save the file, which can be quite annoying. If you like I can send you a file with the appropriate specs in. The only value that differs for the modelling AFAIK when comparing Celestion to some other manufacturers is the Xmax which will affect the maximum spl/wattage charts. Their measure is based on the assumption that the driver starts to behave in a non-linear fashion as soon as the speaker moves enough for the voice coil to start to leave the magnet gap - the method of calculation is usually listed on the specs. From what I've gathered from Alex and others, this is generally overly conservative compared to other manufacturers' methods, which are based either on distortion analysis or a calculation adding in a correction factor. For example, Faital list a driver (PR300). It has a 12.5mm voice coil and 8mm gap depth, and they give an Xmax of 4.92mm. The BN300S is nearly identical (just 0.5 mm shorter voice coil) yet has an Xmax of just 2mm according to Celestion's method. The Faital is a cast frame and likely a better driver, but the gap between the Xmax figures probably exaggerates the difference in performance. I've recently finished testing the first prototype of a cabinet built around the Celestion NTR10-2520D. This has a calculated Xmax according to Celestion of 4mm, but subjectively to me sounded pretty good up to what should be much higher than this, and positively creamed an Eminence Deltalite II with Xmax 4.2mm based on distortion analysis. Long story short, you can probably work to an Xmax of more like 3 or perhaps even 4mm (optimistic but comparable to lots of other manufacturer claims) with the BN300S, just use your ears when you crank it. What really matters is staying well within Xmech/Xlim, the value for mechanical damage. It's not listed on the celestion specs but when I emailed them about the NTR speaker they told me the Xlim value was 13mm, with braking starting to make things sound nasty around 10mm. They'll probably tell you if you want to know for the BN300, I'd guess around 8mm maybe? Oh yeah, Pe is the watts rating, nominal ohms will calculate automatically from Re. Make sure you're using the winisd pro alpha version. Edited March 27, 2011 by LawrenceH Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted March 27, 2011 Author Share Posted March 27, 2011 Cheers Lawrence! I'm just using the bog standard WinISD i downloaded ages ago, i'll get the other one. What are the differences? I have got the file pretty much done, was just short of the Sd value. Ta Steve Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted March 27, 2011 Share Posted March 27, 2011 [quote name='lemmywinks' post='1178959' date='Mar 27 2011, 11:06 PM']Cheers Lawrence! I'm just using the bog standard WinISD i downloaded ages ago, i'll get the other one. What are the differences? I have got the file pretty much done, was just short of the Sd value. Ta Steve[/quote] Tbh I can't remember, sorry! But I remember there was something that was pretty useful in the 'pro' version - perhaps it's to do with displaying cone excursion for a given wattage? It's still free. Just fired it up and Sd for the speaker should come in at 346.4cm^2 That's an oddball driver the orange label, it has such a high resonant frequency for a bass guitar application. I suspect it was really designed with sealed multiple-driver cabs in mind, eg a 4x10. You'll have to watch the amount of bass you put through it especially if you put it in a reflex cab. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted March 27, 2011 Author Share Posted March 27, 2011 Ah, thanks again! Yeah it was originally used in Schroeder 4x10 cabs, i got it unused for a very good price with a view to making a little light 1x10. It's going to be used with another little 1x10 and only with one side of a Superfly so it's not going to be pushed hard at all, just something to use as another practice cab. I think i'll be getting the ply quite cheaply through a colleague, the covering is free from work and i already have quite a few parts knocking around, so if it doesn't sound satisfactory i haven't lost much. Quote Link to comment Share on other sites More sharing options...
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