BMS Drivers
- Thread starter dgwojo
- Start date
Cross over the second woofer anything above 200 Hz, and you'll have a mess of lobes to contend with.... :thumbsdn:
Heh. 9844s gonna kick NOW!! :yes:
Actually, there is a very well regarded JBL/THX design that PURPOSELY uses the pattern-narrowing behavior of close-vertical-stacked 15" woofers, to MATCH the narrow vertical dispersion of a horn.
In this case, the 511 has about a 50 degree (vertical) x 100 degree (horizontal) dispersion, in rough terms... with about a 600 Hz crossover point, the woofers should have about the same, at that frequency, resulting in good "pattern match" at crossover. Could result in really GOOD power balance...
Regards,
Gordon.
Yup, Gordon, as in D'Appolito MTM, the phase interference may be used to advantage in an engineered system.
I count that as falling within the "Contend" set....
Hillman
Don't Start No ****
Wow, Tommy likes his new speakers and so easy to put those 811's back in the 19's. Listened to The Cars, first album The Cars that I cleaned the hiss up on a bit and some Van Halen, Sounded Great. MF Lpad adjustment set just above low max and HF on M of optimum. Any higher on the MF and it makes my ears bleed (shrill). All those neat sounds are there where they should be. Used a Sony DB930 in 2 channel and tweaked the EQ a bit for the base, MF & HF set flat. I am real impressed. :thmbsp:
Darned, I thought you'd hate them and I could snatch them up from you!! :tears:
Stuck an L-pad on there, and got just the opposite.. 4 ohms arcross the driver and 8 ohms in series sounds about right.
That's ~12 dB additional attenuation. BMS specs at 9 - 10 dB more sensitive than the Altec drivers, so it's proving out to be true in actual practice in existing systems, then.... :yes:
:thmbsp:
What drivers did you replace, and where are your control settings now?
I just don't know how to express it. Smaller than the 811B horn flange, even, the little buggers are stupid good once dialed in properly. :yes:
Duffinator
Spin The Black Circle
I've heard both the 4550 and 4552 CD's on JBL waveguides (both composite and plastic) and they did sound amazing. I'm glad to see these are working as a viable replacement for everyone. :thmbsp:
Is anyone doing an A/B comparison between your old and new CD's, like just replacing one and listening back and fourth, maybe in mono?
Is anyone doing an A/B comparison between your old and new CD's, like just replacing one and listening back and fourth, maybe in mono?
Replaced Original 802-8G's in Model 19's HF at the P in Optmum, MF at the last M, May tweak some more as I listen, but sounding pretty good right there.
It always blows me away, when you make change and you start hearing things in songs that you've known for years and years. Just how many times can that happen? Yes.. this is a very good upgrade.
I did the comparison with 902's, the efficiency mismatch really made it very hard, one thing to consider, there's something magical about these when played in pairs, I can't explain it? :scratch2:
You've already discovered it when you measured the DCRs of a dozen of these drivers. It's the uniformity.
I've posted response curves of multiple BMS drivers measured concurrently on several occasions here, showing that the curves virtually superimpose, sometimes so well you can't even tell how many are there.
How does that translate to performance? Imaging. The precision and stability of the phantom image depends upon the two sources being uniformly matched across the frequency spectrum.... :yes:
Edit: To illustrate, here's Gary's 802-8Gs fresh from reconditioning by GPA (top) as compared to four BMS drivers. Which are going to generate the best imaging in a system? Yes, the scales are identical:
skywave-rider
Slumming in Akihabara
I'm doing my big 902 vs 4552nd vs N-800 vs M-19Z vs whatever errors I can throw into the mix tomorrow. I hope I have all the right hardware, tools etc., because I'll be on foot and not in walking distance to anywhere. I have scavenged L-pads from previous x-over in case I need to pad down the BMS. If all goes well (yeah, right...) I'll post results on Lansing and ship 902s to you, Zilch.
This will include a mono listening shootout between 902 on N-800 and 4552 on whatever x-over I find is best for that.
:sigh:
This will include a mono listening shootout between 902 on N-800 and 4552 on whatever x-over I find is best for that.
:sigh:
HEY!
It got awfully quiet over here in the 4552nd department.
If these suck, it's O.K. to say that too, y'know....
I don't know about everyone else but I'm just plain enjoying mine and not even doing any tinkering, sometimes "silence is golden", I think that's the case here. I have to commend you for going out on a limb on these, it takes some real guts to have fellow members spend a couple of grand on these sight unseen and unheard!! I'm very pleased with them and to be truthful, they'll actually save me money in the long run as I won't be so interested in evey Altec horn driver that comes along, my priority has shifted to more of these. Thanks again for all the help, I hope you're enjoying the 4540ND's that you bought, Dave. :yes:
Wiredbecker's pair are going on JBL OASR "Dr. Seuss" horns, and mine on little EV HPT 94 constant directivity tweeter horns. We'll report the results once our respective projects are complete.
[Note: Power tools are involved, and there'll be pics....
: ]I have sealed my predictions in an envelope and given it to the UPS guy for safekeeping....
spaceman
Registered Lunatic
Not yet, but I can do that tomorrow. Sorry for the big delay on input, built me a new PC, & it turned into a longer chore than expected, lol. The BMS drivers have been patiently waiting, and since I have 2 pairs of 811-Bs, it'll be easy to compare to the 808-8A drivers. I'm not sure how many of you are familiar with them though, they don't seem to be "as" common as 902s. :scratch2: