Can someone tell me if this curve on the 802-8G with no horn attached looks normal? I'm just surprised the FS is about 700hz. I have two and both look the same. In FS wouldn't go lower with a horn attached right?
If it's really that high I think this would explain why some recommend an 800hz crossover frequency even on the 511B (Just reading around)
Thanks
802-8G.jpg
- - - Updated - - -
Sorry looks like my image came through looking fuzzy.
802-8G2.jpg
I thought 802G were only used down to 1200hz and 802D and earlier were used down to 500hz in factory systems? Maybe I?m getting the 802G confused with the 902 usage though
Oh rats really?Originally Posted by Elitopus1
I bought these a while back and one had a bad coil so I sent them in to GPA and had new diaphragms and recharged.
GPA lists their 802-8G to 500hz so wouldn't mine be the same with their diaphragms? Or are they stretching the specifications on that driver?
Like I said, I might be getting the 802G and 902 confused. Bowtie or someone else knows for sure.
I know that while GPA lists the freq response of the 802-8G as 500-20khz, the crossover they recommend is a 1200hz unit.
https://greatplainsaudio.com/wp-cont...Spec-Sheet.pdf
My own opinion is the 802D and 802G sound best crossed over at or above 800hz. Even on a 500hz horn like the 511b.
Last edited by Elitopus1; February 5th, 2020 at 02:01 PM.
Absolutely no reason the 802G can't be used like any other 802. Tangerine phase plugs do not need a higher crossover.
Bear in mind the mass of air in the horn. That mass will load the driver, and yes, fs will drop. GM likely would be better at explaining.
That air load is why drivers blow when operated below horn cutoff. The diaphragm isn't adequately loaded.
Small format Altecs IMHO sound better at 800 or 1200. If I wanted to go to 500 I would use a 288.
Your neighbors called. They like your music.
Great thanks!
Can't read the scale, but yes and frankly, was expecting a 707+ Hz Fs for a 500 Hz XO point, i.e. a very good ROT is to tune a 4th order band-pass [BP4] alignment 1/2 octave above desired tuning, though having never known actual specs, not sure what to think since BP4 alignments I've designed using point source drivers has been within a Hz or two accurate. Ditto a bunch of DIYers.
GM
edit: After looking at some other's measurements, it appears the 1/2 octave ROT is still intact as the 0.707x 686.4 = ~485 Hz tuning clearly shows up here: Altec 511B horn compared to the GPA MR931
Last edited by GM; February 6th, 2020 at 04:55 AM.
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Interesting I didn't know that.
If that horn / driver combo will do 500hz that would be great. I don't like running those large woofers to high. I'll have to experiment but assume I'll compromise as best I can between the woofers / drivers - I'd planed to go active and I have a Pass Labs XVR-1 which is very flexible.
It will do 500. Whether you like the sound or not is a personal decision. I don't.
The 511 unloads at 485 Hz if I recall. Pretty skinny margin since parts in the crossover can be off by 20%. Of course DSP removes that possibility.
Your neighbors called. They like your music.
Hmm, please define 'unloads' since F6 is more like ~400 Hz and its cutoff is right at 212 Hz since it's designed to do 300 Hz for the 730C driver.
There's an awful lot of mis-understanding/information re compression driver power handling in general and the 802-8G in particular, but GPA's Fs for it proves it can handle anything the earlier 802s can.
WRT how it sounds, that has as much, if not more, to do with the horn it's attached to than the driver, i.e. it's 'voiced' [entire BW is shifted a little higher] for the small Mantaray and 811, so more CD horn EQ is required for the 511 plus more mouth damping to ~delete its 'honk', reflections back to the throat and 'let through' the 8G's superior HF response. Apparently the plastic phase plug doesn't handle the 511's relatively strong mouth reflections hammering away at it too well.
Factor in there's no need in a typical HIFI/HT app for high power, the driver's 8 w rating is all that's needed, so plenty of Xmax left. Worst case is someone may need to add loading caps to fill a 10 car garage with a pipe organ symphony.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Bookmarks