Hi Guys,
I have the above speakers and a pair of replica A7 cabs made from very good grade plywood to the factory plans.
I have a pair of 811B horns....
My question is about the X-Over frequency - should I go for 800 cycles or 1200 cycles?
If I buy a pair of 511bs will I be able to use the 902s at 500 cycles?
I have a brand new pair of GPA's replacement diaphragms installed in the 902s
Thanks
Winders
O.K I have learnt a bit from the Altec literature that I found.
I see that my confusion is all centred around a 'loading cap' that I need to install in order to use the 902-8A at 800 or 500 cycles.
It looks to be a plastic or phenolic cap that is inserted before the outer cap.
Are these avialable is the next question - I will check with GPA.
Winders
What is your intended application?
Do your 902's have 7/8 or 1 inch throats?
Which "factory plans" were your cabinets built to?
More specific information should get you more responses.
Personally, with that driver combination my suggestion is to forget about a passive network and actively bi-amp. To my ears the 902 sounds "strained" when pushed much below a 1khz XO point, your mileage may vary.
Not all vegetables make good leaders.
Intended aplication - Domestic Audio system.Originally Posted by bowtie427ss
Plans for LF Cab - Altec Lansing as attached.
Yes that is the sort of info I am also looking for - users experiences with 1200/800/500 cycle crossovers using the 902 (with/without loading cap).
I have not used/setup a VOT system yet so I am looking for advice from folks that have been there and done that.
At this moment in time I have no loading caps so I am steering towards the 1200 cycle X-Over point.
Winders
I second the 1200 choice.
And if I could add a vote for biamping...biamped systems just sound better to me, yer mileage may vary. ..and all that stuff...
It's a lot more hassle though.
Your neighbors called. They like your music.
I'm not sure I agree with your thoughts on loading caps.
I believe they were designed for higher output applications like movie houses. In a home hi-fi application, they are not really necessary, and for that reason are often not used by these folks. Loading caps are not rare, so you could experiment with and without to see what you prefer.
Since you probably have the home hi-fi 902 diaphragms from GPA, I would assume you would like the drivers without loading caps.
Most factory applications using these components were crossed at 800 but many folks like the higher x-over point. I believe the venerable Model 19 was crossed at 1200 and many consider this the hallmark of Altec home application systems.
On loading caps, virtually all Duplexes use them, so many home systems Do have them. It is not as simple as you think.
All later apps had the 1200 Hz crossover, you will find most 902's crossed at 1200 not 800. You are confusing with older systems.
Your neighbors called. They like your music.
Have you a schematic, tube possibly, that you like?
Getting 4 really nice output transformers might be a daunting task. Maybe Triode Electroncis SCA 35 set with EL-84s? Then pay $500 for a quad of Telefunken? Man I could get caught up in this big time if I'm not careful. There are lot's of nice sounding guitar tubes but I haven't an idea in the world about hi-fi. Maybe Valve Art? Do they make a EL-84? They make a nice KT-66 but in my opinion it's too fragile in guitar amps. On and on.
Last of the World's Great Human Beings, well maybe one of the last? OK, just an ordinary slacker then.
What?
The small format drivers all had the same throat size. They all mate to the same horns. Confused by this comment.
1200 hz works well. Find some N1201-8A or M19 crossovers and be happy. These are much better than the older 800hz units. You can tweak mid vs high, and they are quite good.
You will tweak active x-overs forever.
Domestic use, this works well. You don't need loading caps.....felt in the rear cover is best. Loading caps were meant to limit over excursion......if you get it that loud in your home, your ears will bleed.
BTW, Dickenson says the 902-8a is the best sounding HF driver, and I agree.
Ron
Enjoying Altec Speakers since 1972
Thanks guys.
Ron yes I have now a copy of the Model 19 X-over and will build that as I see it has addressed quite a few issues and can be tuned to taste as opposed to changing crossovers infinitum!
I guess a Model 19 cab would have been better then but one can change the porting/Fb of the 825/A7 cab quite easily by way of the front "boards" - so I think I will give it a go like that first.
Best
Winders
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