Altec N501-8A Crossover Design Query

[ngccglp]

Hi,

Anybody knows whether the N501-8A is a first order design? I have added a tweeter JBL 2405 and want do a bandpass for the mid horn so that I can use the 2405 from about 8 khz onwards. I will be tapping the signal from the mid horn terminals, which means the 2405 already has a capacitor in series from the N501.

I'm using a crossover calculator to calculate a 3 way, but noticed the capacitor value also changes for the mid as I vary the crossover freq for the 2405. Does that mean that, besides the inductor, I have to add capacitors in series to change the resultant value (i.e the cap in the N501 + additional cap) to that shown by the calculator.

Thanks.

[spkrman57]

2nd order Butterworth with L-pad on HF section.

How about using a 1 ufd cap in series with the UHF unit and connect directly to the crossover input, not off the HF output, would be simpler with less phase problems.

Ron

[ngccglp]

Thanks Ron.


Thought about that, but I cannot control the volume of the 2405 if connected directly to the crossover terminals.

Can I just implement a 2-way first order crossover after the N501? Anybody can advise on the value of the capacitor and coil needed if I want to cross at 8000 to 8500 hz?

Thanks.

[spkrman57]

The Altec 500hz crossover was generally used for the 416/515 LF driver and 802/902 HF driver usually on a 511B sectoral horn.

If you were using something like that, run the HF out normally and you will most likely find that with a 1 ufd cap in series with the UHF driver the level match will be very close. If it needs attenuation, then use a L-pad.

Also, add a 15 to 20 ohm resistor across the 2405 and I doubt you will need the L-pad. All you are doing is adding a little air to the top end!

If you have other design considerations, let us know what you are using and we can see if you have special considerations to be looked at.

Hope this helps!

Ron

[Robh3606]

Just drop a pot in there with the cap. Take a look at the N7000 and 4333 for ideas.

http://www.jblproservice.com/pdf/Network%20Schematics/N7000.pdf

http://www.jblproservice.com/pdf/Network%20Schematics/3133A%20Network.pdf


Rob:)

[ngccglp]

Thanks Ron, Rob,


Yes I do have an objective, that is to use the 2405 to cover a larger spectrum instead of just adding 'sparkle'.

I used to own a pair of 4333s and really liked the highs produced by the 2405, and also because of the harmonics, the leading edge of drums are sounds sharper and tighter. I verifed that by inserting a simple 2-way first order crossover at 8 khz between the 802 and 2405. Indeed I could hear a marked difference, I could follow the bass lines and the drums tightened up.

My concern is, whether I need to consider the values of C/L in the N501 when I design the 2-way crossover?

Or can I make the N7000 and insert it between the 802 and 2405? If I do not intend to add the Lpad for the 2405, how should the N7000 circuit be modified?

Also, I understand there's a N8000. Any idea what are the values of L and C? JBL seemed to pair it with smaller compression drivers.

Thanks.

[ngccglp]

Hi,

Just complete assembling the N7000. First impression sounds good, its seems like a good match for the N501. I will listen to this for about a week to get used to sound.

I would appreciate if someone could provide the L and C values for the N8000. The schematic should be the same I supposed.

Thanks.