811B Driver & Diaphram needed

[69SG]

I am Putting together the components for an
Altec 846 Cabinet I built.
I want to use it for the speaker for a Keyboard Synthesizer.
I have a 15"421-8H, 809-8A crossover and a 811B horn.
I think I need a 808-8A driver to match the power handling ability of the 421-8H.
Is it possible to find one of these any More?

Thanks
DougBays

[Tom Loizeaux]

Sure! Check eBay twice a week. I'm sure you'll find these sooner or later. There are also other sources, but you usually will be paying more to these speciality houses that deal in vintage pro audio gear.

Tom

[Alex Lancaster]

I think it would be easier, cheaper and have more power capacity with a 2425 JBL, there are lots in eBay; some have the 2 hole Altec pattern, or You can redrill Your horns for the JBL 3 hole.

Alex.

[69SG]

That Is an Interesting option.
I will have to investigate.
I wouldn't want to deface the Horn with a drill
But to find a two hole...
Great idea

[Alex Lancaster]

If You do not want to drill the horn, which is easier, You can drill & tap the driver (1/4" NC), I´ve gotten some from eBay already tapped.

Alex.

[69SG]

Alex
What kind of power are we talking
I'm not shure what the 808-8a has.
I think it can handle more than the other ones.
I think the 15"421-8H (Woofer)is rated ot 150.watts.
The JBL driver around 100 or so?
I have a 801-8A and a 809-8A Crossover
I can't see any difference between the two except the number
may have somthing to do with the year model or something.

[Alex Lancaster]

Doug:

I don´t have specs for the 801, but from the scarce Altec info I have:


802 Al diaph: 40 watts continous program

2425 Ti diaph 70 " " " @ 800 Hz
100 " " " @ 1.2KHz or higher

The 150 w for the 421 sounds right, You already have it, but an E140 will blow it away.

If You want the whole vintage Altec way, go for it, but it might be more expensive and less efficient.

ALJ.

[69SG]

Alex
You certainly have me convinced about the 2425.
Especially since the altec drivers are virtually extinct.
I will say this I can not see how the JBL horn part (bell)
can even come close to the Altec. THe Altecs just look like they mean business.
Now I'm sitting here thinking about how good my A7's with the 416 thumpers and 811B sounded 25 years ago with my Altec receiver ( Darlington Transistors). I can't see how a sterio could even sound better.
But what we are talking about is a strong speaker system for Key board syntheszer.
That E140 is surprizing 400 peak 200 continuous.
I have been in a time warp or something.
I need to get current.

Doug Bays

[Alex Lancaster]

Doug:

Certainly the 511´s, 811´s, to say nothing of the 1505B´s look great, but they are 1930´s technology (Westrex), a 2370 looks cheesy, but works better.

For keyboard, a 2425 and E140 will be great, I think Your xovers and 811´s will work fine, I would use a 400w/ch amp, for enough headroom.

Alex.

[GordonW]

Amen to what Alex said- keyboards are BIG power hogs, bigger amp is better. Better to have the amp NOT clip, the speaker will last a LOT longer, especially those $$ horn diapragms...

Regards,
Gordon.

[69SG]

Well I Won the bid on a 2425 16 ohm driver.
I screwed up because I need a 8 ohm.
My crossover is a Altec 801-8A
The bass Driver is a Altec 421-8H.
I guess I will be able to use the 811B horn with this 2425J Driver but the power will be reduced to half.
Is this correct?
Any thoughts on this is appreciated.
Thanx
Doug Bays

[Tom Loizeaux]

The biggest problem with the 8 ohm/16 ohm mismatch isn't effiency, but the 16 ohm resistance will give your 16 ohm driver a differant crossover point from that passive 8 ohm crossover (one octave to be specific!)
You could put a 16 ohm resistor(50 watt?) in parallel with the driver, change the diaphragm to an 8 ohm version, or get a simple active crossover and bi-amp your speakers!

Tom

[Alex Lancaster]

Hi.

Yeah, 16 ohms are a lot more common, one of JBL´s standards, IMHO, the easiest is changing the diaphragm, either OEM, lots of $$$, or a P-audio one, to me, they sound the same (with regards to Dr. Harman).

Alex.

[69SG]

Hi Alex
That's a smart move.
I just looked at
http://www.alliedelec.com/catalog/pf.asp?FN=1030.pdf
Where I but a lot of parts.
I found an adjustable 0 to 25 ohm 75 watt
wire wound resistor.
Part number D75K25R $16.00
That should do it.
What Im wondering is the magnet on the driver.
Is a 16 ohm driver more of a magnetic force than a 8 ohm.
Will a 8 ohm diaphram fit a 16 ohm driver.
we are talking $136.00 for a 16 ohm
compaired to $75.00 for a 8 ohm.
http://www.speakerrepair.com/ocsdiaphragms.html
Doug Bays

[Alex Lancaster]

69:

The expensive one is JBL, the cheaper one is not.

Look harder for a convenient P-Audio dealer, You will be pleasantly surprised.

An 8 ohm resistor in series will waste half the power, I hate even L-pads.

Alex.

[69SG]

I'm not shure but I think I got a good deal.
I need another opinion Though.
Any thoughts would be appreciated.

69SG
(WhiskeyDeltaBravo)

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2371828683

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2374842284

[subwoof]

if you carefully peel back the mounting gasket on the 2425, you will see 2 additional holes for the altec mount.....

use an exacto knife to remove the paper and viola!


sub

[69SG]

I was pleasantly SURPRISED!
It got here today.
And the two bolt inserts was allready exposed!
My LUCKY DAY hahaha....Great!
Thanks
Doug Bays
69SG

[cdh61]

not sure if you found some altec 808 8as, i have 4 in very good condition with spade symbiotik 8 ohm diaphrams, let me know if interested, cdh61

[69SG]

I am checking one more time.
I ordered a LDRD-2425 8ohm Diaphram

http://www.rssound.com/Diaphragms.html

for a 2425J Driver (Impedance 16ohms).
I am assuming from the previous posts
the 8 ohm diaphram will fit it.

If a 8 ohm diaphram will work in a Driver
that is labled 16 ohms,
Why do they even write it on the Magnet.
I'm guessing the Impedance is drived from the resistance
in the windings of the diaphram.
And the Driver is just a big magnet.
I don't know but am I missing something
in this scenario?
I know they are both 1" diaphrams.
It just seems to me that JBL would have
put some kind of minute difference
between the two so they wouldn't
be inter changeable.
As you can tell I have not done this before
I would hate to screw up a brand new diaphram
out of stupidity :-)

[Speakertown]

Be sure and measure the ohms of the diaphram that's
in it, it may already have an 8 ohm replacement! This
is very common. The jbl label only refers to what was
installed at the factory. An 8 ohm dia. will measure under
8 ohms....usually it will be around 6 ohms DCR.

[69SG]

So in other words the 16 ohm that's printed on the driver is just telling what came inside from the factory originally,
and the so called (8 ohm and 16 ohm driver) Magnets
are identically the same and can take either diaphram?
>>>>>>I hope.
This sounds very logical to me.
This has just taken a big weight off of my mind.
Thanks
Doug Bays

[mikeofw]

I have some 808-8a drivers for sale. If interested email me at mikeofw@aol.com. I have a bunch of other nice Altec stuff for sale as well. I was collecting old Altec but my house is turning into a music store. <grin>

Mike

[audiobarn]

I wish I had gotten involved in this post earlier. In terms of the 808 the symbiotik diaphragm is no longer made. Fortunately ALTEC produced their "Pascalite" diaphragm in the late 1980's and it has as much power handling capacity as the symbiotik and sounds as good as the aluminum diaphragms of the 802 (802 and 808 are identical motors, just different diaphragms. Bill Hanuschack at Great Plains Audio will rebuild any of these drivers for cheaper than you can buy a JBL diaphragm for. He also sells the diaphragms direct for any ALTEC drivers (except symbiotik).I would have advised you to try for a 909 driver as well which would have worked well. The alnico 802 series goes down lower better than the 909 but with the 800 hz xover that is not an issue you would have had to worry about. The 909 or 902's will be available from Iconic soon (the parts are backordered temporarily).