Acoustical Loading Caps

[eibei]

Good Evening to All:::

Can anyone provide dimentions for an Altec loading cap - part number 23370.

Thank you in advace of any info provide.

Lynn

[Russellc]

I just removed the loading caps from my 902-8Bs. Looking them over, I do not find a part number on them. If this is what you are after, I would be happy to measure whatever dimension interests you.

Russellc

[eibei]

Hi Russellc:::

Thank you for taking the trouble to measure your 902 end cap.
The 23370 cap was listed on e-bay [$50.00 - alot of money for an end cap?]
I jumped to the conclusion that it MIGHT a type "T" [for 800 series drivers.]

Lynn

[Roland N R]

End caps covering the diaphragm were designed to prevent driver overexcursion and increase power tolerance. Most favor the driver's sound w/o them....not what I call important for home use.

[eibei]

Thanks Roland:::

My limited knowledge hurts me. I understand the function of the loading cap. If the normal cap provides the proper load [per Altec] then the "T" cap [it seem] would have to provide more loading. Is that correct?

If the "T" loading cap reduces the space between the diaphram and it'self then the diaphram has a more limited travel. Hence reduced loudness. Correct?

Lynn

Lynn

[Roland N R]

Lynn:

Basically loading caps by placing a rear load limits diaphragm overexcursion allowing the diaphragm to tolerate a few more watts of power which represents more volume output. Most like the sound better w/o them just using the felt pad. For home where little power is used you have no need for them.

For pro sound they do increase power tolerance slightly but usually it is simply better to use symbiotic.

Diaphragm loading has to do with the compression ratio of the phase plug and the pressure of the air column in the horn itself. Remember that the diaphragm movement of compression drivers in horns is minimal. They work on different priciples than direct radiating drivers where the actual volume of air moved by the cone determines output. In comp drivers a high pressure wave is created by the diaphragm's movement of air and its compression by the phase plug. This minimal volume but high pressure wave is then converted by the horn's gradual increase in size(the principle of impedance transformation) into a low pressure but high volume which at the horns mouth couples efficiently with the low pressure ambient air to produce air waves = sound.


Gas laws
PV=nRT
PV=K =Pressure x Vol = constant

Therefore when pressure goes down volume goes up

[jdiamantis]

Call good ol' Bill At GPA.

I got a pair of loading caps for $6, and end caps for around $20 for a pair of 902-8B's.


John Diamantis

[eibei]

Thanks John - no force - no break.

Lynn

[eibei]

Hi Roland:::

I just tried to ask you a big long question about driver resonance.
Pushed the wrong button somewhere and the whole thing was lost "in space" Some kind of a warning!!!

Anyway the gas theory helped alot.

Thanks,

Lynn