Any update on the Model 19 Supercrossover???

[Altec19]

Hi Todd,

Does the M19 Supercrossover have the potentiometers of the original design or have they been exorcised in the interest of expelling the demons of distortion? Has a price been determined yet?

Thanks!

[Todd W. White]

Ha Ha!

Yes, the L-pads will NOT be a part of the design.

Currently, we can build the following:

1) An updated version of the original Model 19 crossover. This uses the original design, but replaces the old-style parts with newer, better sounding alternatives. Iconic Mfg. Co. can build them on an aluminum plate which is mounted inside your existing cabinet. The kit includes 12-gauge leadwires, the crossover, mounting hardware, and a full set of installation instructions. Pricing is quoted based upon current availability and cost of parts. E-mail me at [email protected] for a quote.

2) An updated version of the original 604-8K crossover. This uses the original design, but replaces the old-style parts with newer, better sounding alternatives. Iconic Mfg. Co. can build them on an aluminum plate which is mounted inside your existing cabinet. The kit includes 12-gauge leadwires, the crossover, mounting hardware, and a full set of installation instructions. Pricing is quoted based upon current availability and cost of parts. E-mail me at [email protected] for a quote.

As for availability of additional crossovers, all good things take time, but eventually come to those who wait. Seems like every time we turn around, something slows us up, but here's the pecking order for other crossovers as it stands for now:

* Currently, the design for the SuperCrossover for the 604E is in progress. We have an original, stock "E" on loan from a friend, and will be using it to test our prototype. Once it is finished, we will announce it's availability for orders. We're hoping to be able to announce them by Nov. 1, 2004 or sooner.

* Following the desgin for the "E" SuperCrossover, the one for the "G" is most likely next. Since the main difference between the two is impedance, this should be a fairly easy changeover, but remember: not everything goes as planned. If all goes well on this, expect it by December 1, 2004. Another one for the "G"'s that have tangerine radial phasing plugs may be necessary, too, but we're not sure yet.

Development of this one may be delayed, though, because Iconic mfg. Co. is expecting to announce the availability of a completely revised 16" coaxial loudspeaker that promises to be the best sounding of it's type ever produced. Included with it will be a SuperCrossover designed specifically for it. If the design work on these items can be moved up, then it will follow closely on the heels of the release of the SuperCrossover for the Altec-made "E", then work on the one for the "G" will commence.

* After the release of the new speaker and crossover, work on the SuperCrossover for the Altec-made Model 19's SuperCrossover will begin.

Hope this gives you an idea what Iconic Mfg. Co. is working on...

[Altec19]

Hmmmm . . . Here is my conundrum: Do I bi-amp my Model 19s or update the factory crossovers with current components or wait for a Supercrossover?

Thoughts, anyone?

[Todd W. White]

Personally, I wouldn't biamp - there's more to crossing over in a Model 19 (or any other system, for that matter) than just "crossing over"....

[DeadFish]

I'm weeping with you, Altec Fan.

I've had my 19s a while now, and have had ALL sorts of adventures trying to get them to sound right.
My path took me to putting away my Bryston bi-amping and moving to tubes.
Very happy, but cannot tell much, if anything, using the l-pads.
And I've got this Bryston 10b active crossover just hankering to be used again.
So I'm in the same spot.
It's just that we are pretty far down the list, and I've been on lists like that before....

Ayup, I feel your pain..

[boltupright]

I've found that bi-amping the model 19 to be a bit probematic to get them to sound right, I had good results by switching to the 511b horn, but the speakers do sound good stock with tubes powereing them.
My Quad II monoblocks are a bit sloppy with the woofers, but sound awsome powering the horns.
I tried a 60's Sherwood intagrated 30 watt stereo, & it sounds excellent with the model 19 stock.

[joyspring]

Altec Fan:

1. Potentiometers (the large wire-wound types appropriate for this application) will add negligible - if any - distortion.

Switched fixed resistors are probably a better choice as the variable controls are vulnerable to airborne environmental contaminants with attendant intermittent problems.

2. Bi-amping is almost always the preferred choice with caveats since, as Todd stated, the original Model 19 crossover does more than just `cross over'...

Have a look at Jeff Markwart's Vintage Model 19 Schematic:

http://home.earthlink.net/~jmarkwart/id7.html

On cursory glance, it looks like an assymmetric crossover with a 12db/oct. low-pass and 18dB/oct. high-pass. In the HF section, however, C4 plays an interesting role -- note how it `bypasses' the pad?

There's a bit of response-shaping in the final octave, taking advantage of the 5-8dB higher efficiency of the HF driver to flatten the response in the upper octave(s).

No, the 802-8G (or whatever Altec used in the Model 19) was nowhere near flat in the final octave, Tangerine(tm) phasing plug nonewithstanding; hardly any 1.75" V.C. 1"-exit compression driver is...

Both Altec and JBL made use of this type of bypassing in the late 1970s/early-1980s at the expense of greater risk of HF driver failure (from harmonic distortion). This risk, of course, was mitigated by inexpensive, high-power solid-state amplifiers that were becoming more commonplace at that time.

Anyhow, if you do choose to bi-amp, you must consider this additional EQ necessary to faithfully mimic the original passive Model 19 crossover.

3. Also, there is no time-delay compensation (in the LF section) in the original Model 19 crossover for the length of the 811B HF horn. Since the crossover frequency is 1.2kHz and the approximate time-offset is ~1 mSec., it falls right on the border of audibility according to the Blauert-Laws criteria.

Most professional active crossovers (i.e. - Rane AC22) have continuously-variable analogue delay (cascaded all-pass filters) that will correct the physical offset.

Todd: will the Model 19 and 604 Supercrossovers incorporate passive time-delay as well?

4. Properly EQ-ing your Model 19s will make far more difference than whether you use solid-state or tube amplifiers (or special wires or other similar nonsense); while there are important amplifier-specific parameters, they may be considered entirely independently of whether the amp uses tubes or silicon components.

If anything, especially considering the high dynamic range of current (and forthcoming) digital formats, high power, low distortion and especially low noise should be primary considerations in the interest of faithfully reproducing your source media as well as protecting your HF drivers.

BobR

[Altec19]

All very interesting points, gentlemen. One additional thing I should ask of Todd: What is it that makes the Supercrossover "Super"? I am assuming that it would be constructed of premium parts just as the upgraded original model is right now. What further enhancements or problems are addressed by it's "Super-ness"?

[Todd W. White]

BobR - As far as time delay in the Iconic SUPERCrossover for the Altec Model 19, there will be none, in the traditional sense.

Traditionally, time delay in a crossover is done electronically. That is, with an electronic crossover and a delay circuit.

Since the SUPERCrossovers are of passive design, this is not possible.

However, the man who does our crossover designs, Jerry Hubbard (Head of Acoustics at Altec Lansign from 1982 to 1992), offers the following;

When designing a passive crossover, many things come into consideration. One aspect, of course, is to correct for any defects in the frequency response of the high and low frequency components in the speaker system itself while maintaining all of the good characteristics it has at the same time. Not as easy to do as one might think..

Another of these is the phase relationship between the two devices, particularly at crossover. In the SUPERCrossovers, as in all the designs Mr. Hubbard does for Iconic Mfg. Co., the key is to design the device correctly so that the low and high frequency devices perform in phase at crossover. If you achieve THAT, then, as Jerry puts it, "You're pretty much done." This is because when you get the two in phase at the crossover point, there is no need for time delay circuitry, as you have achieved your goal.

Altec Fan - As far as components in the SUPERCrossovers are concerned, they will utilize, for example, ribbon core inductors: things like that. All super high-quality components.

[joyspring]

Todd:

"Since the SUPERCrossovers are of passive design, this is not possible."

UREI, Tannoy, JBL, Bag-End and many other monitor system designs incorporate time-delay using passive crossover components.

"the key is to design the device correctly so that the low and high frequency devices perform in phase at crossover. If you achieve THAT, then, as Jerry puts it, "You're pretty much done." "

`In-phase' is suitable for steady-state signals but sounds in nature (particularly music) are temporal as well. Hence, `in-time' can be considered just as important as `in-phase'.

Western Electric noted the problem, Heyser, Blauert, and Laws quantified it, and Garde, Leach, Linkwitz, Lipshitz, Vanderkooy, Bullock, Small and many others sought to solve it.

Bill Putnam (Universal Audio/UREI) employed Ed Long and Ron Wickersham to offer a solution as a commercial product (the UREI Time-Aligned(tm) series). They designed a real-time analysis system for developing time-correction in passive networks. Bag-End is a current commercial provider of branded Time-Aligned(tm) loudspeaker systems.

While UREI (and others) perhaps did overstate the baneful effects of non-time-alignment, it is indeed audible, particularly on percussion and piano. Remember that it is the UREI line that markedly improved the Altec 604 and extended its useful professional life until 1980.

It's also nice to note - from a purely engineering standpoint - that my UREI 811As will produce clean square waves on-axis an octave above, an octave below and at crossover. ;-)

BobR

PS - I will provide references to applicible JAES papers on request.