Measuring performance of crossover

[Michael_in_Ohio]

My stepfather died last year, and I inherited his Altec Lansing Flamenco speakers. They're 50 years old. I picked them up yesterday. Today I opened one of them up and took a look around. The woofer looks perfect. But I am wondering about the N-800F crossover. A Google search suggests the two capacitors in it may be bad. The obvious solution is to simply replace the caps. But the crossover is completely potted, and I've heard it is a total PITA to get access to any of the components in it. So I need to test the crossover using external means.

I have a function generator and oscilloscope. Would that work? Sweep a sine wave from 20 Hz to 20 kHz? Should I connect the crossover to the two drivers and monitor the voltage across each, or use two 16 Ω resistive dummy loads?

I also just placed an order for the Dayton Audio DATS V3. Can I use it to determine if the crossovers are O.K.?

Thank you!

 

[mhardy6647]

Sorry for the loss of your stepfather, but 'grats on the acquisition of his Flamencos. The late Stereophile raconteur Art Dudley famously had a pair (of Flamencos, that is). Flamencos (which are pretty much identical to Valencias other than the cabinet style) are great loudspeakers... but, like many (perhaps all) Altec loudspeakers, the crossovers don't do the drivers justice. In other words, I'm not sure it's worth investing any effort into them. You should find "improved" XO designs on the internet that indeed will be better than the N800'll ever do.

EDIT: In disclosure, I used my 16 ohm Valencias with their original XOs quite happily, but when I went to 604E Duplexes I went with the Mastering Labs XO. The stock XOs for the Duplexes were a notorious weak spot, responsible for much of the reputation for harshness that Duplexes of that era had.

You should be able to look at output of the XO as a function of frequency using a function generator and a good AC voltmeter. I will say that the treble attenuator is almost certainly "noisy" (scratchy &/or finicky) at this late date.

Hifihaven has a pretty active & knowledgeable "high efficiency" group with an Altec concentration (jncluding me ). Audiokarma has, I think, an Altec subforum, too. You might want to nose around one or both.

 

[fpitas]

I might be jumped on and beaten for saying it, but I'd think about using the Model 19 1200Hz crossover. Those also offer 3rd order electrical on the horn. In later days Altec (and everybody serious) stopped running horns to such low frequencies and realized that steeper filters were appropriate.

 

[fpitas]

Model 19 crossover (EACH)

The Great Plains Audio Model 19 is a 12-dB/octave, dual-section, passive crossover network, with a center frequency of 1,200 Hertz. This crossover is designed to replace the original crossover used in the famous Altec Lansing Model 19 speaker system. It may also be used with some of our Great...

great-plains-audio.myshopify.com

 

[DVDdoug]

The capacitors are probably OK. Electrolytic capacitors can age & deteriorate but other types usually don't

The capacitors in a crossover have to be non-polarized (because of the AC audio signal) and non-polarized electrolytics are a bit of a "hack" so they probably didn't use them.

 

[mhardy6647]

I might be jumped on and beaten for saying it, but I'd think about using the Model 19 1200Hz crossover. Those also offer 3rd order electrical on the horn. In later days Altec (and everybody serious) stopped running horns to such low frequencies and realized that steeper filters were appropriate.

It would be worth a try.
Modern conventional wisdom suggests not using the 811B horn below about 1 kHz. The Nineteen's XO has some HF contouring, too (doesn't it?) that probably helps with the treble extension if at the cost of a bit of sensitivity.

As I have mentioned here (and elsewhere) before, Philistine that I am, I kept a pair of Altec Santiagos and actually sold my Valencias to a 'tubes 'n' horns' buddy who has been very, very happy with them. Mind you, I enjoyed the heck out of the Valencias, but their bass output is limited (frequency-wise, not quality-wise) and mine had some cosmetic issues (most notably a missing fretwork grille on one of the pair) that would've been tedious and/or expensive to mitigate.

EDIT: That 416 woofer is beautiful, though, isn't it?

Santiagos use a sealed box alignment with a woofer that is not held in much regard by the Altec faithful -- but I like 'em just fine.

 

[fpitas]

Of course the obvious thing to do is hook up the microphone and get on the horn axis and measure FR.

 

[fpitas]

It would be worth a try.
Modern conventional wisdom suggests not using the 811B horn below about 1 kHz. The Nineteen's XO has some HF contouring, too (doesn't it?) that probably helps with the treble extension if at the cost of a bit of sensitivity.

As I have mentioned here (and elsewhere) before, Philistine that I am, I kept a pair of Altec Santiagos and actually sold my Valencias to a 'tubes 'n' horns' buddy who has been very, very happy with them. Mind you, I enjoyed the heck out of the Valencias, but their bass output is limited (frequency-wise, not quality-wise) and mine had some cosmetic issues (most notably a missing fretwork grille on one of the pair) that would've been tedious and/or expensive to mitigate.

View attachment 322054

Santiagos use a sealed box alignment with a woofer that is not held in much regard by the Altec faithful -- but I like 'em just fine.

Any of those old Altecs don't go low by modern standards. A sub or two is a good idea.

 

[fpitas]

Santiagos use a sealed box alignment with a woofer that is not held in much regard by the Altec faithful

A friend and I built a kit from Altec with sealed woofers and 811s, but those woofers were the 411-8A.

Altec Lansing 411-8A 15" LF Woofer Speaker 8 ohm - PAIR - vintage ! | eBay

A nice pair of Altec Lansing 411-8A 15" LF Speakers 8 ohm. Pulled from Santiago speaker cabs. Had rubber foam surrounds replaced. Cone is 100% original. Excellent working condition and sounds great. Shipping is an estimate and will partial refund if less expensive to your location. Local pick...

www.ebay.com

 

[mhardy6647]

Any of those old Altecs don't go low by modern standards. A sub or two is a good idea.

Absolutely true, but the Valencia et al. are (extra) handicapped by putting a Voice of the Theater woofer (albeit a slightly lesser one) in a small vented box.
That said -- I wouldn't mind having a pair of Altec Magnificents... just 'cause, you know?

A friend and I built a kit from Altec with sealed woofers and 811s, but those woofers were the 411-8A.

I have two NOS 411s in the basement in their original boxes.
... but, yeah, my Santiagos are the "A" morph, with the 413 woofer.

Sorry for the digression @Michael_in_Ohio !

 

[fpitas]

Absolutely true, but the Valencia et al. are handicapped by putting a Voice of the Theater woofer (albeit a slightly lesser one) in a small vented box.
That said -- I wouldn't mind having a pair of Altec Magnificents... just 'cause, you know?

If you do, use 3rd order on the 511s

 

[fpitas]

Sorry for the digression

But just think of the Altec trivia he's learning!

 

[fpitas]

he Nineteen's XO has some HF contouring, too (doesn't it?) that probably helps with the treble extension if at the cost of a bit of sensitivity.

I had forgotten about that; but yes, a rather interesting gentle treble boost circuit to flatten the horn response.

 

[fpitas]

Altec Lansing Model 19 crossover issues

Hello, My brother has a pair of gorgeous looking model 19's that were not working properly, so we investigated them this weekend. 67132 One of them were working properly, but on the other the diaphragm in the compression driver was teared and the low frequency driver had a rub. We mounted...

www.audioheritage.org

 

[fpitas]

The Zilchified circuit:

High Efficiency Speaker Asylum

Audio Asylum - High Efficiency Speaker Asylum - Need speakers that can rock with just one watt? You found da place.

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[Deleted member 48726]

They might be bad. They might be good.

-Do they sound alright?
-Do they measure alright?
Then don't worry.