i'd like to bi-amp using a pair of dynaco mk iv's on the bottom and a puny SET for the top. has anyone here tried this? has anyone here compared vintage drivers using pi theory to the kits that wayne sells? I am just a retro dude in many ways so the altec gear means something special to me

by the way, wayne if you read this, I live down in norman!

EZ

• my current weird but wonderful speakers

There are several Altec fans here, and tons of JBL guys too. See the link below for others building π Speakers using Altec components.

• π speakers with Altec parts

btw, a set of 4 Pi Pro's would definitly rock your living room as well as 511B's over a 15 inch BR, and they are much more compact and wife friendly.

• Chicago Horn Club

The T/S params for the 416b are xmax=.15 Vd=19.20 Fs=25.1 Vas=26.47
Qts=.32 Qms=7.05 Qes=.33 Vid=.2

for the 515b its xmax=.18 Vd=23 Fs=24.7 Vas=19.7
Qts=.17 Qms=7.5 Qes=.17 Vid=.22

I was thinking of an 802/511 combo for the HF. despite some "alweako" cracks, to me a paper cone and alnico magnet combo sounds awesome. does anyone have alternative suggestions for horns/drivers?

On the crossover, I thought bi-amping necessarily meant an active x-over before the amps. Is this not actually true? As you can tell, I know little audio theory. the dyna monos put out around 35-40 watts the hf amp will be 2-3 watts.

thanks again, EZ

• TS parameters for altec drivers

I was trying to HELP HIM AVOID being sucked into the "vintage is always better trap" where he will buy a beat set of mismatched drivers, send them off to be remagged, have them still suck, buy new 'phrams, and lose interest eventually. Or obtain his 825/828 boxes, then find out he needs a friggin' subwoofer too...Sam

You wrote:

>> The T/S params for the 416b are xmax=.15 Vd=19.20 Fs=25.1 Vas=26.47 Qts=.32 Qms=7.05 Qes=.33 Vid=.2

PiAlignments for that motor specify a cabinet of 8.5 cubic feet tuned to 30Hz. It further recommends a rectangular port having inside dimensions of 6" x 10.5" and 14" long.

The response is nice and flat, with a -3dB point of 40Hz and -10dB at 23Hz. This is a very nice speaker with very full bass.

>> for the 515b its xmax=.18 Vd=23 Fs=24.7 Vas=19.7 Qts=.17 Qms=7.5 Qes=.17 Vid=.22

This one needs a much smaller cabinet. PiAlign recommends 3.35 cubic feet tuned to 54Hz, and suggests a rectangular port of 4.75" x 8.5" and 6" long.

The response of this one is also nice and flat, but the system is tuned about an octave higher. It's -3dB point is 55Hz and -10dB is 45Hz. This makes a nice full range speaker, with less bass but in a smaller cabinet.

>> On the crossover, I thought bi-amping necessarily meant an active
>> x-over before the amps. Is this not actually true?

It's an issue of semantics, really. All the stuff that makes up our amplifiers, preamps and crossovers has reactive circuits (signal modifiers) in addition to the transistors or tubes (signal multipliers). An active crossover is one where the circuit that performs signal splitting contains amplifiers, or active components, as an integral part of the crossover filters. But you could as easily install some reactive components in between amplifier circuits. Some call this a line-level passive crossover, since the filter is passive.

Take care!

Wayne

>PiAlignments for that motor specify a cabinet of 8.5 cubic feet
>tuned to 30Hz. It further recommends a rectangular port having
>inside dimensions of 6" x 10.5" and 14" long. The response is nice
>and flat, with a -3dB point of 40Hz and -10dB at 23Hz. This is a
>very nice speaker with very full bass.

that would be a perfect lf set up 4 me. can you suggest somewhere where I could read about what it means to "tune" a cab to a particular frequency? Also, are there theories about how to allocate the 8.5 CF between width, heigth, and depth? Also, can you tell from pi align the upper -3db point (in relation to the 500 v 800 xover issue)?

>Some call this a line-level passive crossover, since the filter is
>passive.

so with this method, does each amp still only get fed the range its supposed to reproduce and see directly its driver on the other end?

>Let's get together sometime soon. Next time I'm headed towards the
>city, I'll drop you a line. If you come this way, you might do the
>same.

I would like that very much. my email is angus@ou.edu

Kevin aka EZ Angus

I don't know specifically where to find more information on the internet, but I suspect there's tons of it out there. First, do a search for "Helmholtz" to find information on his work. Then, do a search for "Thiele" and "Small" for information about theirs. I'm not sure you'll find the work of Brian Davies online, but I've got a copy of his excellent implementation paper, which I can make available if you're interested.