What's the equivalent of multiple drivers?

[Svante]

Originally posted by tcpip

What's a Basta simulation?

Look in my signature.

Actually, the differences are minor. I'd earlier pointed to the published spec sheet, now I've posted my measured parameters. The Fs matches very closely, the Vas was missing in the published spec sheet, and the only parameter which differs very widely is the Sd. I have good reason to believe the published Sd was a typo: 65 sqcm when the corrrect value should be 95 sqcm. Other than that, it's the same driver.

I couldn't even connect to diyaudio last night. It's now Sunday morning here, and I'm able to connect once again. Was the site out of action sometime about 12 hours ago?

Hmm, 95 sqcm corresponds to an effective diameter of 11 cm, and 65 sqcm corresponds to 9.1 cm. This diameter is usually measured on the middle of the suspension. How did you measure?

[tcpip]

Originally posted by Svante
Look in my signature.

Am still looking.

Your program seems to do more than Unibox... it seems to model the active and passive filters too. I wish it would also take the SPL curve into account.

Hmm, 95 sqcm corresponds to an effective diameter of 11 cm, and 65 sqcm corresponds to 9.1 cm. This diameter is usually measured on the middle of the suspension. How did you measure?

I measured from middle-of-surround to middle-of-surround. And I believe I'm pretty accurate, because the published figures for GR-Research M130 says Sd is 95 sqcm. I'd initially measured 91 sqcm, but after reading the GR Research spec, I decided to use 95 for my calculations.

As I'd said earlier, the driver I'm using has been supplied in an OEM version to GR Research, as per unconfirmed news.

[Svante]

Hmm, do you think you could list your measured values for a single drivar again? It seems the data sheet is pretty messed up, the resonance frequency is clearly about 57 Hz in the impedance curve, not 80. And to arrive at a compliance of 0,92 mm/N Vas needs to be 11,9 litres, unless the Sd is really 65 cm2...

So, the best would be to abandon the data sheet completely, and go with your measured data.

I got this, "The parameters of each driver were: Fs=80Hz, Vas=5.3L, Qes=0.63, Qms=2.53, Le=0.292mH, Re=5.8Ohm, and Sd=95 cm2.", But I'd like Bl, too. It says 19.73 on the Unibox sheet which would be 6.58 for the single driver. Is that right?

Anyway, given these values, Basta tells you this:



The blue curve is a 106 litre box tuned to 55 Hz, the red is a 80 litre box tuned to 60 Hz. (from top to bottom at 100 Hz) electrical impedance, maximum output level, and system response. I included a baffle step for a baffle of 0.2 by 1.2 metres. The maximum output level is limited mainly by the cone excursion, which is only 0,75 mm for this driver as far as I can tell from the datasheet.

[wintermute]

Originally posted by simon5


Yes WinISD Pro is very good. You have some graphs that Unibox doesn't have, like the Impedance Phase response and Group Delay.

In the end, I would say... use both of them to check everything hehe!

Been away for a few days, quite a few posts since! I was wrong the other day when I said winisdpro only could model parallel drivers, I hadn't dug deep enough, I found a whole pile of extra stuff when I clicked on edit driver.....

Unibox does have Group Delay graphs, and has a very nice graph which compares the group delay of vented, sealed, passive radiator and bandpass enclosures. Also has max excursion graphs, as well as others, just click on some of the additional tabs down the bottom of the spreadsheet

I always like to model in more than one program to get make sure they at least agree to an extent... just be aware (aimed at TCPIP) that if you go with the default Winisd pro settings you will possibly get spl graphs slightly different to unibox as it uses (from memory) different default values for leakage and damping

TCPIP, I too thought winisd was a bit too basic, and thought the same of winisdpro for a while, but since I looked at the latest version, and especially since I found that there were more options hidden away that I hadn't come across before (not available from the standard menus) I'm probably going to have a closer look at it.

I thought that it was nice it asked what alingment you wanted, but found it frustrating that after I chose it, I couldn't find a way to change to another one without starting from scratch again....

I find winisdpro to be a bit clunky to use.

Tony.

[tcpip]

Originally posted by Svante
Hmm, do you think you could list your measured values for a single drivar again?

Sorry I took so long to respond. Have not been able to even visit this site for the last three days.

I got this, "The parameters of each driver were: Fs=80Hz, Vas=5.3L, Qes=0.63, Qms=2.53, Le=0.292mH, Re=5.8Ohm, and Sd=95 cm2.", But I'd like Bl, too. It says 19.73 on the Unibox sheet which would be 6.58 for the single driver. Is that right?

I don't know what the BL is. I didn't do anything to measure it. In SW, the BL is shown as data that the user has to input. And in Unibox, the BL value seems to be a derived value (written in red). I don't know how BL is derived by Unibox.... that value of 19.73 is derived.

The blue curve is a 106 litre box tuned to 55 Hz, the red is a 80 litre box tuned to 60 Hz. (from top to bottom at 100 Hz) electrical impedance, maximum output level, and system response. I included a baffle step for a baffle of 0.2 by 1.2 metres. The maximum output level is limited mainly by the cone excursion, which is only 0,75 mm for this driver as far as I can tell from the datasheet.

Cone excursion is certainly going to be almost 1mm each way, going by the physical inspection of the drivers.

[RJ]

Martin J. King has a worksheet to calculate Vas & Bl;
http://www.quarter-wave.com/Models/MathCad_Models.html
If you don't have Mathcad Lite, I can E-Mail you a copy.

[Svante]

Originally posted by tcpip

Sorry I took so long to respond. Have not been able to even visit this site for the last three days.


I don't know what the BL is. I didn't do anything to measure it. In SW, the BL is shown as data that the user has to input. And in Unibox, the BL value seems to be a derived value (written in red). I don't know how BL is derived by Unibox.... that value of 19.73 is derived.


Cone excursion is certainly going to be almost 1mm each way, going by the physical inspection of the drivers.

OK, so unibox probably calculates BL from Qes, Re, Mms and fs.

The 0.75mm Xmax I assumed was calculated from the "coil height" and "air gap" numbers. If the coil is 6.5 mm long and the air gap is 5 mm, there will be a length of +/- 0.75 mm that keeps the gap filled with copper. Beyond that the number of turns in the gap will decrease with excursion, ie Bl becomes nonlinear and distortion increases.