equalizer?

**whitebroncoii** · June 26th, 2010, 10:41 AM

Graphic equalizers come in two distinct flavors; variable-Q and constant-Q.

Constant-Q
Years ago (before modern audio analyzers) an audio manufacturer made a name for themselves and convinced many that the constant-Q was the way to go. This type of eq paints a very pretty picture on a 1/3rd octave audio analyzer. The filters are very steep and choppy at boost/cuts less that 6 - 8 dB. More boost/cut and the filter looks like . . .

Variable-Q
All of Altec Lansing equalizers (up to and including the "programmable" 8000 series) are variable-Q. Each filter overlaps the adjacent filters. The more you boost/cut, the more frequencies are affected. Gentle boost/cuts are suggested. In fact, most recommend cut only for a playback system.

The 1753A was the last 1/3rd octave eq offered by Altec and it is nice piece. A pair of Altec 1653 equalizers would be worth big-time bragging (1/3rd octave, cut-only).

Please keep in mind that most Altec electronics were sold and used for professional/commercial applications. Most used units have likely been running since they were new and they typically start having contact/component issues after ten years of steady use.

**Panomaniac** · June 26th, 2010, 12:13 PM

Ditto on the Rane. Ashly, too makes good sounding EQ. Stay away from the old Klark-Teknik stuff! Awful sounding. I didn't know how bad until we swapped it for an Ashly. Maybe their new stuff is better.

Have never used the Altec EQ. Think I ran Urei for awhile - did they make an EQ?

EDIT: Here is a good deal on a 1653.
http://cgi.ebay.com/ALTEC-LANSING-16...-/260410642629
You'd need another one for stereo

Oh wait! This guy has 2 - 1 not working. With above you could have a pair for not much coin.
http://cgi.ebay.com/Altec-1653A-1-3-...-/130388470094

**Old Guy** · June 26th, 2010, 12:56 PM

Originally Posted by whitebroncoii

All of Altec Lansing equalizers (up to and including the "programmable" 8000 series) are variable-Q.

Odd- Altec claims the 1753 is constant Q

Are you sure about that?

http://www.altecpro.com/pdfs/vintage...g%20Manual.pdf

Wouldn't be the first time an error on a spec sheet, but that is a big one.

**Panomaniac** · June 26th, 2010, 01:16 PM

OG, thanks for the spec sheet. The cool thing I noticed was a 0.7V nominal level. Great for home audio!

**DSauro** · June 26th, 2010, 02:29 PM

Yes, ditto on the ME60, 1/3 octive from 25hz to 20K. I picked one up a few years back to replace my ailing Altec 729A Acousta Voicette, that I had in continous service for 30 years. After Iratec brought the 729A back up to spec, along with a couple upgrades, I've gone back to it. 1/3 octive from 63hz to 12500. I like that it takes out, and does not boost, then compensates with a broadband reinsertion gain. BUT, just try to find one of those in good operating condition.

**just me now** · June 30th, 2010, 10:54 PM

i like my white 4400s w/ no trannies/crossovers....
4400 - Retired Product - White Instruments Div. C Van R, Inc.

perhaps a purist would prefer the 4000 ( i think??? could be wrong) series
(if not, i meant the cut only versions)

they do pick up hum/noise from close electrical components (read amps) though...
requires some distance from other equipment IME....

or i can run it in the loop of a Urei 1620 preamp/DJ mixer and it seems quiet too...

good luck,

try to audition other friend's gear, if at all possible, is all i can say!

*EDIT*
darn, posted after reeading only a page of posts...
sorry for the repeat!

parametrics are nice too. agreed!

**magnarc** · July 1st, 2010, 01:53 AM

John

Thanks for your posts, very informative and useful.

Do Shure still sell the 57 pin 3 hot?

Nat

**techmecca** · July 1st, 2010, 09:16 AM

current product - according to the literature - is pin 2 hot

I just looked on the interwebs and my previous statement needs to be modified or corrected

Back in '90-'92 when this was happening I remember Shure and others making the case that with so many units in the field and users expecting consistency across time that they were in a bind, but I can see that current literature states that positive pressure on diaphragm makes positive voltage pin 2 with respect to pin 3. 1992 was about half my career in audio ago and many many other things have gone by since. I was not on the standards committee and I am no expert on the history of what all happened - though I do remember Shure was one of the manufacturers that was being mentioned.

The best thing to do, really, is not to assume anything. You need to test and verify so you really know.

There are various ways to do this

One way is to put up a new mic that is stated to be pin 2 hot and compare this to others just by placing them side by side pointed at a common source and seeing if they add or null when you bring them up on a mixer and sum them? you can use music or use a tone like 400Hz or so that has a wavelength that is pretty long so that having the diaphragm of one mic ahead of another by an inch or so is NBD and just test you mics against each other - and of course your cables and mixer inputs should all be right and no phase reverse buttons down, EQ out and so on.

Off the shelf phase testers exist? they are none of them flawless but they do work under controlled conditions. You want a two piece system with a transmitter box that has a little speaker in addition to electrical output connectors for mic and line level and a receiver with a microphone in addition to connectors for mic and line level.

Mine is from Galaxy Audio. I see these from Rolls and Alphaton and I am sure there are others

You can DIY this as well - I've seen various DIY projects so with a little search these will turn up.

BTW when we went through all the mics in the studio we just changed them as needed while testing, verified the correction and moved on - I did not take notes? roughly a third needed to be changed and I can't remember specifics - some were tube mics and others were dynamics and some were Shure and sone were EV and some were Altec and so on.

For electrical absolute phase test you can make barrel connector with diode in it connected with cathode to pin 2 and anode to pin 3 so that it clips off the positive peaks (works at levels around +4 - not at mic level) This is really rude but with a scope it's pretty easy to see if the flat top stays on top. There is a BBC stereo test signal that clips the top off the left channel only so you can do channel ID as well but I digress

this thread was about EQ - right? well we are well off the track now...

so to further complicate things on the absolute phase front I will open a whole other can of worms and leave with this? (running as fast as I can)

be vary careful about using these phase checker boxes on speakers like, oh, say Klipsch Cornwalls and immediate relatives? and many horn based systems including Altec. Absolute phase is NOT going to be consistent across all the drivers especially in systems where the acoustical centers of the individual drivers are not aligned - which is most speakers but especially more so in horn-based systems

You'll find the individual driver polarity in an absolute sense is not maintained because it is more important to have phase alignment driver to driver at the crossover points. Passive crossovers induce phase shifts and designers, if they are thinking about this, will work crossover points, phase shifts and speaker polarities to obtain smoothest response across the crossover points

I'm sure this has been discussed here somewhere

now I will quietly sneak out of the room

**Panomaniac** · July 1st, 2010, 11:05 AM

Oh yes, I remember the great pin 2, pin 3 debate from the early 90s. Glad to see that it has mostly worked itself out.
Smart move testing and fixing all the mics, bravo!

BTW, active crossovers also cause phase shift. All crossovers do. Just FWIW.

**whitebroncoii** · June 26th, 2010, 11:59 PM

Originally Posted by Old Guy

Odd- Altec claims the 1753 is constant Q

Are you sure about that?

http://www.altecpro.com/pdfs/vintage...g%20Manual.pdf

Wouldn't be the first time an error on a spec sheet, but that is a big one.

No, I was wrong. Please forgive me for my failing memory and thank you for the correction. The 1753A was an attempt to get on the constant-Q band wagon. I guess I really do not recommend this model . . .

BTW: The way to tell for sure if an eq is constant-Q is to look at the graphs showing boost or cut in increments. A constant-Q filter will always have the same "slope" and the base width changes (see the 1753A data sheet). Imagine how your response would look with 3dB of cut on every slider! It would look like a saw blade.