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View Full Version : 807-8A Specs anybody?



Yidaki
03-19-2005, 09:45 AM
Hi there,

i'm searching for the specs of the 807-8A drivers. Does anybody know the frequency range? And what's the productiion year / range of this driver?

Thanks for the hints!

Yidaki

Yidaki
03-19-2005, 09:52 AM
Ouch, sorry - i found it: http://www.lansingheritage.org/html/altec/specs/components/807-808.htm

However, does anybody of you know if they are worth to try - i know the 288-8k drivers would be better but i don't have the money and i never listened to any altec horn drivers so i'd like to start with something "affordable" ...

Earl K
03-19-2005, 10:11 AM
I'd say don't bother wasting your money .

- The 806 and 807 drivers use a lighter weighted magnetic assembly which reduces usable/listenable HF response. The fact that these older alnico magnets are most likely partially discharged will further reduce their listenability - especially the 807 models which were thrown into Altecs' small PAs in the 70s' and have a very high likelyhood of having been overdriven ( which can lead to demagging a magnet ) .

- Even the heavier magnet 802c(d) & 808a versions from that period don't offer enough HF performance to support buying them .

- Buy the 902-8b driver ( not the 908 ). It may be a ferrite magnet - but it's diaphragm creates one of ( if not ) THE smoothest 1" exit driver(s) I know .


:)

Yidaki
03-19-2005, 10:27 AM
Thanks, Earl - what brilliant info. I'll check the availability and price of the 902-8b drivers. I'm running a Jabo Horn with a Beyma driver (2" - set to 760Hz - 20kHz) but since i found this wonderful site and learned about all these wonderful speakers, i'm mad about testing an altec driver. :D

Earl K
03-19-2005, 11:36 AM
Yidaki,

- OK , ya got me, just what is Jabo ?

- Which Beyma driver model # ?
( Some of their 2" exit drivers have a 3" diaphragm while others have a 4" diaphragm. ) As far as I can see they all have titanium diaphragms. You'll find Altecs' aluminum diaphragms a lot smoother - though - it may seem dull at first .

- In case you didn't realize it, Altec Pro is out of business, so you are best to shop on eBay for 902(s) . Or buy new from "Iconic" Speakers .

- I'd like to see a pic of your Jabo Horn.
( You can post jpgs here that are file size less than 180 kb and 800 pixels or less in width. )

:)

Yidaki
03-19-2005, 12:09 PM
Jabo horn is a tractrix horn, 52 cm wide. It's 2" but i have a 1" adapter. I use them on top of some custom made 160 liter, 120 cm high cabinets - two 12" drivers (low ~20 Hz to 120 Hz, mid 120 to 760 Hz). The 2" Beyma driver is the CP750TI (0.6 - 20 KHz, 8 Ohms, 110 dB, 1w @ 2m). It sounds amazing but i'm always curious that's why i'd like to test altec. I'll post some pictures tomorrow - it's dinner time now here in Germany ... ;)

And, yes, i know, ... ebay. I'm watching all Altec items there since i joined the forum last december. :D

Cheers, Yidaki

Yidaki
03-20-2005, 05:52 AM
Ok, so here are some pictures, earl.

Notice, the box in the bottom pit is a custom made mono amp for the bottom 12" low driver. The 12" mid and the hf horn (Jabo horn / 2" Beyma driver) use a 5-channel amp (Ceratec Penta). Pre amp is a Alchemist Nemo/Forseti APD15A integrated amp. All channels go through a dsp crossover (behringer ultradrive pro dcx2496) where the crossover frequencies are set as described above.

Earl K
03-20-2005, 06:24 AM
Hi Yidaki

-Thanks for the pictures ! :D
- Great looking setup - very nice . :)

- I don't own , nor have I heard here at home any of the large Beyma compression drivers. I know I've used them in PAs that I've run in different places. I went to Beymas website so I do realize that the diaphragm in your driver is a titanium dome with a Mylar surround. Beyma also talks about the controlled dampening of unwanted resonances using the Mylar.
- Do you find this Beyma driver smooth sounding ?
- After looking at the spec sheet, your driver seems to be quite attractive to use.
- I'm curious about them - so - I probably need to buy a pair .

- I have here at home a pair of B&C de900 drivers. They are neodymium magnet with a very similar diaphragm/surround setup to what the Beyma advertises.
- I find this de900 really underdamped sounding for home use ( somewhat edgy & brittle sounding , etc. ) - though it's a fairly good PA/SR driver . I also found it didn't offer nearly the same resolution as the Altec 288.

- The reason I use the Altec 288-8K for home listening is that I find I like the overall damping characteristic of it's aluminum diaphragm. I'd say it' "critically damped" right out of the shipping container. Passive circuitry can add more dampening . The 288 is pretty easy to "overdamp" by component selection. Right now that's where my system is at. Unfortunately, "a damping characteristic" is a sort of spec. that doesn't mean much on paper. One needs to buy / listen / and then determine "likability" .

- Im curious about that Beyma - it has good HF extension / but then so does the B&C .
- Do you have any experience or opinions you'd like to share about the B&C large format drivers ?

:cheers:

Oh BTW, I like your conceptual design for the speakers / with the sides rising up to partially embrace the tractrix horn . Nice clean lines !

- What make of 12"s are those ?

Yidaki
03-20-2005, 08:45 AM
Hi Earl, cool that you like the setup!

(To be fair: the speakers are built by a friend. He has built around 160 pair speakers the last 20 years. I just had the wish, did the finishing and do the listening. :D)

I'd say the beyma sounds realy nice, smooth and with a good resolution. Even very detailed music with high frequencies sounds briliant without disturbing. (I mostly listen Jazz, pref. DMP, Telarc ...) But then, i don't have other drivers to compare. ;)

One thing that makes the beyma driver more precise is the cable i use. It's a DNM Reson Single Solid Core. Very thin (0.5 mm diameter). It's a sub bass killer but very nice for hf.

Yes, the 288-8k is what i'd like to test one day. I don't miss anything with the beyma but i'm realy curious. My friend says, the Altec's although they are good, you'd pay for the name and the vintage. But when i read here, i'd say there must be more. Hmm ...

I'm curious what you'd say about the de900 and the 288-8k drivers with a DNM reson cable.

Btw, what'd be a good price for the 288-8k pair? And what about the 16k version?

<edit:>

Ah, the 12" are also Beyma - the low is a 12K200 4 Ohms, the mid is 8 Ohms.

I just phoned with my friend and he says that the B&C de900 driver is not good for hf. An alternative for the beyma would be the BMS 4590 (2", coax, 300 to 22kHz) - in his words: "the best driver you can get for this kind of horn / Jabo".

:cheers:

Earl K
03-20-2005, 10:42 AM
Btw, what'd be a good price for the 288-8k pair? And what about the 16k version?

I'm not sure since I haven't tracked prices on 288s for a couple of years .

Up until about 2004 a person could easily get a decent pair for under $400.00 . In fact I remember a pair out of Montreal that didn't sell at $300.00 ( 2002 ). Recently, I've seen similar prices to that $400.00 / I've also at least 50% higher. Back in 2001 a seller was lucky to get $300. a pair since everyone wanted the alnico 288-8G (or 16G) model .

The biggest problem is the cost of shipping. They weigh 30lbs (13.6 kg ) each. I really think the only sane option is to buy locally when dealing with that much weight .

Also, the aluminum diaphragms tend to age by "work hardening" from the tiny bit of flex they go through. This changes their response when compared to brand new diaphragms.

I'll have to try different wire types sometime . It's something I've just never pursued .

Thanks for getting your friends opinion on the de900. Now I know it wasn't just me .



:cheers:

Yidaki
03-20-2005, 11:08 AM
Thanks, Earl. Ya, buying local ... problem is: there are not much altec components back here in germany/europe.

At the risk of going on your nerves: what about the 288C drivers? I didn't find any specs or description what's the difference between the 288c and the 288-8k/16k drivers. There are some 288c drivers for sale from time to time at prices around 600 EURO's. And is alnico better or worse? What's the difference - is it audible?

I now that the phrags will age - are replacement phrags ok / worth?

Sorry for the newbie questions. :o:

Earl K
03-20-2005, 01:41 PM
Hi Yidaki

The 288C & 288D were retired from the Altec catalogue about 30 years ago.

The 288C was 24 ohms and the 288D was 16 ohms .

Any 288C you buy will be ancient and quite likely in need of having the magnet regaussed . It's also likely the diaphragm is newer than the driver ( that's probably a good thing ). In fact, I'd insist on a visual & electrical inspection of the diaphragms before buying. No 288 has much response beyond 14 or 15K. That means a lot of people will want to add a tweeter.

The 288C & D were superceded by the 288-8G and 288-16G as well as the completely new 291-16G .

You can get some good info on Altecs' large format drivers at the Altecs' Unofficial HomePage (http://alteclansingunofficial.nlenet.net/)
LOOK HERE ! (http://alteclansingunofficial.nlenet.net/proloudspeakers/lgdriverslit.html) for that info on the drivers .

It's likely worth your while to look at tech sheet #231 over in the Altec Technical Letters section (http://alteclansingunofficial.nlenet.net/publications/techletters/index.html) . This shows that Altec added an 3 extra pounds of alnico magnet to the 3.6 lb 288C magnet to gain a bit of extra performance . There was a couple of db of extra output & I believe the HF response was a flattened bit .


And is alnico better or worse? What's the difference - is it audible?
My only sonic awareness of alnico is when the magnet is partially discharged ( just about always ) and the speaker doesn't give the orginal intended reponse.


I know that the phrags will age - are replacement phrags ok / worth?
Original replacements are ( I think about $200 ea ) while after market types are @ $50 to $ 70.00 . I don't have any experience buying replacement diaphragms of either type . Sorry :( , I'm not really a help there .


hope this helps :)