Onken bass box with 2 Eminence Deltalite ll 2510 10" bass drivers

[revintage]

All of the above designs are wrong. This as Rg of the 300B or 2A3 amps should be added. Something that I forgot.
So instead of adding 0,2ohm you should add in the ballpark of 2ohms. Far to long vents and a box-volume of over 300dm3.

[albertli]

Originally Posted by revintage

All of the above designs are wrong. This as Rg of the 300B or 2A3 amps should be added. Something that I forgot.
So instead of adding 0,2ohm you should add in the ballpark of 2ohms. Far to long vents and a box-volume of over 300dm3.

Lars,

Do you mean this driver is not suitable for the Onken ??

Albert

[revintage]

Hello Albert,

Probably. Could be hard to make the very long port to behave. But you try and decide.

Another thing, about your amps, do you have 4ohm outputs on them? If so, Rg might be somewhat lower.

[albertli]

All my amps are 8 ohm.
I thought I'd put them up for the other project.
Thanks

Albert

[jamikl]

Sorry about that albertli but I have no experience at all with valve amps so was not aware of what has just been posted.
jamikl

[albertli]

Originally Posted by jamikl

Sorry about that albertli but I have no experience at all with valve amps so was not aware of what has just been posted.
jamikl

Np problem. I'm an old newbie and try to learn more too. Actually I've finished some good speakers, but love to try something new.
BR

Albert

[GM]

Originally Posted by albertli

I finally come with a calculation posted by GM and have the following result.

Originally Posted by albertli

Sd 3.501E+00 m^2 effective radiation area of the driver cone

Rg 0.300 ohms total components resistance (xover coil, terminal, wire, amplifier, etc.)

Vas 499309.099 litres air volume driver compliance calculated by the software

vent lenght
L vent 0.006 cm effective lenght vent
L’ vent -9.732 cm corrected effective vent lenght (use this lenght in your vent calculation)

Vent volume -2.959 litres total volume occupied by all vent in the box

Total Box Volume
Vb 613550.590 litres total internal volume of the box
Vb Total 613547.631 litres total internal volume of the box plus the required volume for the vent

Greets!

You mentioned this before, but don't know what you're referring to. For sure, this isn't based on any calculation I've posted.

I'm not good at math either, but fortunately one doesn't need to know any math more complex than addition, subtraction, division to use CMB's spreadsheet [SS] calculator. Unfortunately for most folks who come to these forums though is that it requires you have a basic understanding of what you're inputting when using a calculator that requires more than the basic T/S specs ['Fs', 'Vas', 'Qts'] and in the case where multiple drivers are desired, how to change the specs to get an accurate calculation.

For the math challenged, he further complicated it by using scientific notation and m^2 for 'Sd' instead of the more common cm^2, which is where you messed up, so one must have a conversion chart or program such as 'Convert' to help folks like us.

To convert cm^2 to m^2 requires dividing it by 10,000, so would be inputted as 0.03501 which the SS will display as 3.501E-02.

With this change, 'Vas' will shrink by a factor of 10,000 which will then allow the SS to calculate a more reasonably sized box with vents that can actually be built in accordance with the physical laws of our universe.

Note that I get a ~5.15% smaller cab using CMD's designer compared to mine for a N=6.34 alignment due to the difference in Vas, so there's some minor discrepancies in the 2510's other published specs and of course measured specs may make either off by a higher percentage.

Finally, you only simmed one driver, not two, which requires a bit more simple math to combine their specs: http://www.quarter-wave.com/General/Two_Drivers.pdf

The easy way to design a two driver cab is to just design for one driver and double 'Vb', 'Vb total' and the vent's height or whatever you prefer to do to double the vent area.

You list Rg = 0.3 ohms which might not even account for all of any XO resistance if a passive is used and tube amps, especially SETs, can have a very high output impedance that will dramatically increase the cab's size due to it raising Qts. Also, to maximize wide BW efficiency with these types of amps it's common to series wire drivers to sum inductance ['Le'] and raise 'Re' which also minimizes any added series resistance impact on Qts.

Regardless, like most modern drivers, this one has specs designed to work well in a relatively small cab to meet the performance needs of a prosound application [app] with the design trade-off being lower efficiency, so isn't suitable for a 'pure' Onken loading.

Of course you can either reduce the vent area to as little as 70% of Sd to get them as short as practical and/or accept the stronger pipe harmonics of longer vents which can be damped empirically if they audibly 'color' [distort] the mids too much.

GM

[jamikl]

I was hoping you would drop in on this one GM. I think I used your sheet for the attachment I did but did not realise that the valve amp had much higher output impedance.

What is CMD's designer you refer too?
jamikl

[jamikl]

Ignore the question. CMD is the one I have but I thought you made it available.
jamikl

[albertli]

GM
Thanks for your guidance and I'd try to do the math more carefully.

Jamikl,
Thanks and do give any suggestion you could think of.

Albert