Cal Weldon said:
Greets!
FWIW, cabs with throat openings narrower than the 8" horn wall width are ideally only used with 800 Hz XOs, so unless you know when yours were made they may pre-date the introduction of the 511 in the mid '50s, especially if it has the added brace at the top of the throat that further reduces the low pass filter's area. By the time Altec began using 800 Hz XOs on the 511 loaded M.I. horn cabs circa '70, the 'bean counters' had long since dropped the option due to the A7-500 ~wiping out A7-8 sales, so for those folks with either a keen ear and/or response measuring equipment, there's some subtle sonic gains to be had by reducing the filter area when 811s are used with the larger throat cab.
Note that this applies only to Altec woofers listed for this cab or similar response mid-bass horn drivers since ones optimized for non-horn apps won't have the strong stepped response in the 500-1 kHz BW that you would be smoothing.
GM
Re: Re: Re: Altec 1803B
Greets!
While I agree with, and actively promote, 'BIB' where applicable, to maximize the performance benefits of a 300 Hz compression loaded multi-cell you'll need a much lower HF XO point, especially if the app is multi-channel. Also, ideally you'll need a larger horn unless a really steep XO and/or it's used in a very low power app since even the huge 1803 (http://www.wmeckle.com/BOYD/1803rca1.jpg) is no bigger than it absolutely had to be for acceptable performance in a PA app driven with a ~matching impedance amp and why there's no doubt in my mind this is why all the (relatively few) 1803 loaded cinema installs I saw when they were being dismantled used a 500 Hz XO, though I don't know if these were original or were swapped out when higher power and/or SS amps were installed.
GM
jeff mai said:
Greets!
While I agree with, and actively promote, 'BIB' where applicable, to maximize the performance benefits of a 300 Hz compression loaded multi-cell you'll need a much lower HF XO point, especially if the app is multi-channel. Also, ideally you'll need a larger horn unless a really steep XO and/or it's used in a very low power app since even the huge 1803 (http://www.wmeckle.com/BOYD/1803rca1.jpg) is no bigger than it absolutely had to be for acceptable performance in a PA app driven with a ~matching impedance amp and why there's no doubt in my mind this is why all the (relatively few) 1803 loaded cinema installs I saw when they were being dismantled used a 500 Hz XO, though I don't know if these were original or were swapped out when higher power and/or SS amps were installed.
GM
Altec 1803B
Only if you don't use EQ. And you'll face that issue with any CD horn even if much smaller.
What home app isn't very low power? FWIW, I used an active 24db/octave xover at 350-400Hz with my 1803B.
FYI - the RCA cabinet in that photo is one of the ones I owned and used with my 1803s. Boyd drove 1500 miles to Kansas to pick them up from me.
GM said:
Only if you don't use EQ. And you'll face that issue with any CD horn even if much smaller.
What home app isn't very low power? FWIW, I used an active 24db/octave xover at 350-400Hz with my 1803B.
FYI - the RCA cabinet in that photo is one of the ones I owned and used with my 1803s. Boyd drove 1500 miles to Kansas to pick them up from me.
Geoff H said:
Hi Geoff, the XO's are approx 650 and 5K, 12 dB
Part of a kitchen cabinet set . That is the lower corner cupboard I have stuck up on the wall. It's where I keep my stash...
...of caps coils and resistors.
Thanks buddy. Strong winds and rain mixed with snow here. You really cheer me up.
panomaniac said:
The lower is a Selenium D250-X on the 511 horn and a Selenium D205Ti on the 811. The woofer is a Selenium WPU-1507-QCF.
I knew that this isn't KHCal Weldon said:
.......just because this days my head is full with KH papers and plans (just thinking...thinking....)regarding Selenium.....there is one on pic in post No.15 ......hehe,but dunno number from top of my head .......used as supertweet,temporary with APT80's plastic horn,just for better dispersion.
crossed with two para 0,47UF VitQ in line and pretty attenuated.
Jeez, I just came inside for the back yard where I was sitting in the shade reading a book about Australia and drinking iced tea.
Lovely day, here. The meteor shower last night was wonderfull.
Ah ha, I was supposed to stick the D210s on the 811s to have a listen, never did. How are the D205s?
Re: Altec 1803B
Greets!
We seem to have a 'failure to communicate'. I'm not referring to its CD horn HF roll-off, but the mass quantities of comb filtering going on with increasing frequency between the cells, which no amount of electrical EQ can correct other than a low XO point and/or steep slope, though open cell foam inserted in the outer cells to roll off their HF will help somewhat.
Well, mine for one when it was all together/functioning. I much prefer reproducing all the dynamics a recording has to offer Vs the euphonic clipping of a typical low power tube amp, or worse, the not so euphonic typical SS clipping ckt.. Even with an H.E. system it takes a lot more than 'flea' power to reproduce the +30 dB transients on some CDs.
W-bins do make big sound, but back when I had a big rig I didn't have the luxury of steep digital XOs/TD, so stuck with the truncated, wide BW front loaded 210s. Anyway, nice to see them preserved rather than chainsawed for easy loading into a dumpster like has been the fate of most of these 'dinosaurs'.
GM
jeff mai said:
Greets!
We seem to have a 'failure to communicate'.
I'm not referring to its CD horn HF roll-off, but the mass quantities of comb filtering going on with increasing frequency between the cells, which no amount of electrical EQ can correct other than a low XO point and/or steep slope, though open cell foam inserted in the outer cells to roll off their HF will help somewhat. Well, mine for one when it was all together/functioning. I much prefer reproducing all the dynamics a recording has to offer Vs the euphonic clipping of a typical low power tube amp, or worse, the not so euphonic typical SS clipping ckt.. Even with an H.E. system it takes a lot more than 'flea' power to reproduce the +30 dB transients on some CDs.
W-bins do make big sound, but back when I had a big rig I didn't have the luxury of steep digital XOs/TD, so stuck with the truncated, wide BW front loaded 210s. Anyway, nice to see them preserved rather than chainsawed for easy loading into a dumpster like has been the fate of most of these 'dinosaurs'.
GM
panomaniac said:
Jeez, I just came inside for the back yard where I was sitting in the shade reading a book about Australia and drinking iced tea.
Lovely day, here. The meteor shower last night was wonderfull.
Greets!
Yeah, we're in the midst of an 'Indian Summer' that they predict will last for another 10 days or so, with mostly sunny skies and highs in the low 70s.
No tree shade though, I raked up the last of the leaves/cleaned out the gutters yesterday.Must be nice, 'Hotlanta' is so lit up at night that I haven't seen much of the night sky around here since the late '50s.
GM