New to the hobby - 416-8A and 802D

[sjpd10]

Hi,

As the title says, I'm new to this hobby. I've played with 'ordinary' speakers, designed, built etc etc, till I heard 'Altec's' at a friends place. The naturalness and large 'live' sound was unreal to say the least.

I've come across a pair of 416-8A's and 802D's. The 416's have been reconed with a GPA kit and the 802's have a pair of Azura 425 horns.

Have read and researched as much as I could and thought the Z10 or A19 xover's were ideal till I realized the 802's were 16ohms (read as NEWBIE syndrome).

I'd be happy to read on any thread /link if this topic has been discussed. Would be grateful if somebody could help with how I should go about the xover, or should I try active ? Any information /direction would be helpful. Thanks.

sunil

[sjpd10]

Heres what I found so far, the N-800F used in the 'Valencia's' is close to my needs. The xover is well documented here and here

Will it work ?

[sjpd10]

Ran some impedance curves of the 802D using the WT3 tester (Dayton). The results with the rear cover are totally off - Qts - 2.5, fs - 900hz. Without the rear cover, the fs shows as 300hz and Qts ~ 1.1

Is there something wrong ? Is the WT3 not the right way ?

[sjpd10]

The impedance is ~ 8ohms and not 16 like it is supposed to be. Do I use this to decide the crossover ?

Please help.

[sjpd10]

....and no help.

C'mon people, please help this newbie.

Is it normal to have the TS params skewed this way - one driver measures fine - fs@300hz, the other varies between 900 - 1400 hz.

[sjpd10]

These threads have incredible information on the 8 vs 16ohm crossover.

http://www.audiokarma.org/forums/sho...d.php?t=328530

http://www.audioheritage.org/vbullet...l=1#post197971

[more10]

The impedance is important for the crossover. However, crossovers for horns are difficult to design. You could go active with a digital crossover. Tubes for the horns and transistors below.

[fpitas]

You may already realize this, but the impedance of the driver will be greatly affected by the horn. That crossover was designed to work with an 811B horn.

[Ed Kreamer]

Greetings from Hood Canal

The 802d and the driver used in the 19, I'm betting, are quite a bit different. I'm thinking that the driver in the 19 is based on the 806 with the tangerine phase plug which behaved somewhat differently than the 802, especially at high frequencies. If you decide to use the N800f you may not have the bandwidth you desire. I'm just guessing here, but it may bear some investigation. Or get an old Altec N800 16 and build and ancillary attn./eq like the Altec 30904

Ed

[sjpd10]

Thanks for all the replies. I'm leaning towards active since I have spare amps lying around. Other than attempting to replicate the Z19 response, I'm going to try tuning the bass as well.

Still a fair way but I will post results when it starts moving.

[sjpd10]

One more thing. The earlier owner confirmed the 802D has GPA 8ohm diaphragms, so that's a relief. Only concern is the odd TS params between the two and whether they are to be trusted.

[more10]

I'm leaning towards active since I have spare amps lying around.

Good decision! Please share your plans for crossover.

[sjpd10]

The tweeter impedance mismatch is sorted. Appears the foam that sits on the rear cover was either falling on the diaphragm and/or the leads were touching it. After turning the leads around the periphery of the diaphragm's plastic frame, both drivers measure ~ 300hz and the other params are close enough. I've also put a rubber gasket between the 802 and the 1" to 1.4" throat converter. Seems to help.

Question - I've seen a cardboard gasket with a fine mesh kind of thing and there are also examples of leather gaskets. How important are the gaskets ? Is that mesh really necessary.