A7 vs 9845A

[ClassicComics]

I just want to make sure I am understanding how these speakers compare. I believe they have the same woofers, horn, and drivers, no? Is the only difference the cabinet size? Whould a 9845a make a good center channel with a pair of A7s? Would just like some other input.

Thanks!

[GM]

True, but they are apples n' oranges, designed for two completely different apps with two completely different polar responses, so not IMO.

But the proof is in the hearing, so go down to your local HT Emporium and audition three MTMs, two as vertical mains and one turned sideways for the CC and if it sounds fine to you with a variety of movies with your eyes both open and shut (do shut first), then once level matched the Altec combo probably will too, but if you're not tone deaf I'm betting it will bug you long before the end of a 2 hr. action movie or even just one with a good music score that's done in real three channel stereo as the pioneers of audio meant it to be.

As always though, YMMV.

GM

[ClassicComics]

Why turn the center sideways? This is not recommended when using an accoustically transparent screen.... for example: http://www.seymourav.com/screens.asp

So I am trying to as closely as I can, match my front side speakers as possible. The 9845a will give me the room to build subs underneath it, in a seperate compartment behind the screen. You do not think it will match well with my A7's?

Also, I believe the 9845a's were used in theaters at one time as well....

THANKS!!

<font color="#FFFFFF" size="1">[ July 08, 2008 11:26 PM: Message edited by: ClassicComics ]</font>

[Steve Mac]

You need to ask more questions. Never...ever... draw an immediate conclusion from what appears to be a finite response from Mr. GM.
Question 1 to ask:
What is the polar response of the 511 in a 9845 versus a 511 in an A7.

[GM]

Originally posted by ClassicComics:
This is not recommended when using an accoustically transparent screen....

So I am trying to as closely as I can, match my front side speakers as possible.

<font size="2" face="Verdana, Helvetica, sans-serif">True, but I was trying to make a point about how not having at least a similar polar response across the three main channels can be audibly disconcerting, so short of you acquiring a 9845 to try it out in your system I figured that my suggestion, while not being in any way similar to what you're contemplating, would highlight the issue in a way you can easily understand and if it turns out that at least you find the set-up 'good enough' to enjoy the movies, then your Altec solution will probably work well enough also, at least for you. If a S.O./whoever will be joining you on a regular basis, then it seems reasonable to me that they should have a say in it also.

Bottom line, even if all three channels are EQ'd dead flat and level/phase matched the polar response and general tone of the 9845 will be different enough that while it will be excellent as a CC if you don't need a lot of off axis response, it shouldn't blend well to A7s in panning scenes or when a good three channel stereo music soundtrack is playing.

While I can 'see' 9845s being used in a small mono cinema, it wouldn't be my first choice except possibly in a surround channel back in the early days of Dolby when they were BW limited to a mono 100 - 7 kHz.

Again, if you're serious about making a good match to the A7s, then making just an 825/828's or even an 816's horn section to get a good blend through the 80 Hz - up BW is where you want to be and it will leave you with enough ground clearance to use the sub system as a perch for it.

Note that this assumes your electronics allows just the CC's bass to be redirected to the LFE channel, otherwise you'll have to run all the other channels in 'small' mode also, which means that the LFE channel in theory must be able to handle an extra ~7 dB for 5.1 systems, ~7.8 dB/6.1, ~8.45 dB/7.1.

As always though, YMMV.

GM

[GM]

Originally posted by Steve Mac:
You need to ask more questions. Never...ever... draw an immediate conclusion from what appears to be a finite response from Mr. GM.
Question 1 to ask:
What is the polar response of the 511 in a 9845 versus a 511 in an A7.

<font size="2" face="Verdana, Helvetica, sans-serif">LOL!

Also the major difference between the 9845's direct radiator Vs the A7's horn loaded one. Major difference, with the horn cab 'coloring' the ~100 Hz - up BW until well up into the 511's BW.

I was stunned at how much more natural the 515s sounded when I switched them out of the 210s. I'll never again have anything 'stronger' than a simple waveguide to control the directivity of the critical human speech BW.

GM

[ClassicComics]

I obviously don't know anywhere near what you guys know about this stuff....

so the 9845 has a different driver than the A7? Couldn't I just replace the driver later then?

[GM]

No, I already confirmed they should both have the same components in my first post, though in retrospect the 9845 may have a different XO. The main differences are the cabs and the horn's and woofer's positions in them which when combined with their XOs determines their polar response, i.e. their sound power pattern they project into the room which in turn is affected by the screen, altering it in ways we can't easily predict.

I guess you're either going to have to buy one and try it or just accept our recommendations to either use another A7 just like what you've got or make a horn as I suggested.

GM

[ClassicComics]

It was actually Steve Mac who suggested the 9845 to me in the 1st place. If I mounted all of the horns on all 3 speakers on the top of the cabinets - which was recommended to me on here by several people with the A7's, will that bring them closer? Or were you mainly talking about the woofer? I am not ignoring your advice, I am trying to learn more about this. I guess I will have to buy 1 and see how it works out.

THanks!

[GM]

That will certainly help some, but there's still the major (IMO) problem of being unable to adequately blend the 9845's baffle mounted woofer to the A7's horn loaded ones which are 'focussed' to the point of being mildly 'colored'. Not a problem when the first row is probably 25-30 ft away, but then the baffle loaded A8, the nearest equivalent to what you're wanting to do, is only good for about half that distance.

Frankly, I don't understand what seems like a high resistance to building a simple horn and being done with it. Really, the more you post, the more I'm wondering if you'll be better off overall with all 846Bs or DIY variants and use your A7s either elsewhere or as a separate stereo system in the HT room.

I mean how far away is the viewing area? This is the real criteria as to whether you use horn or baffle mounted woofers.

GM