Altec 416-8B Crossover Frequency Question, etc.

[Spackler]

Hi all,

Long time listener, first time caller.

I've recently decided I would like to try my hand at a vintage Altec/JBL hybrid system and have slowly been acquiring drivers and other assorted relevant equipment.

My initial plan was to follow the Jean Hiraga Onken cabinet plans and I am still leaning in that direction although I've also been giving some consideration to the Altec 620 cabinet.

My room is 12' x 16' with 8' ceilings and my current driver compliment for the project is as follows:

Altec 416-8B woofers
JBL 2446h Compression Drivers
JBL 2380 Bi-Radial horn
JBL 2405h slot/super tweeters
Belden 9497 cables
Werner Jagusch Crossovers

I would like to build the cabinets to house the 416-8Bs while being able to mount the horns and super tweeters on a separate, removable plywood sled up top and am wondering about a decent, workable crossover frequency for the 416s? I've read everything from 500-800hz and have also read that they start to degrade in output quality after 1k. Does anyone here have experience with these that could speak to this subject?

The Werner Jagusch crossovers were purchased locally here in Vancouver from someone who was selling 16 Ohm Valencias and they are the older version that does not allow for the super tweeter (at least not as far as I can tell). I've reached out to Werner who says they can be run at 8 Ohm which is a relief as all of my drivers are 8 Ohm. As far as the super tweeters go, I am hoping to use an inline capacitor although I'm not sure of the value yet and want to experiment with just a 2 way first.

This is my first DIY speaker build project and I currently own Electro Voice Interface Deltas which I will be hanging onto in case this build does not end up being to my liking. I have a Mac laptop so currently can't use WinISD.

Any info regarding crossover frequencies would be greatly appreciated.

Thanks in advance.

Current System:
Pioneer M22 Power Amplifier
Pioneer C27 Preamplifier
Electrovoice Interface Deltas
Wiim Mini Streamer
Cambridge Azur DAC Magic
Technics 1200M3D
Pickering 625DJ Cartridges
Cardas 4S11 Speaker Cables

[GM]

Greets!

What is the XO's point/slope?

Based solely on Altec 416-8B measured, JBL published 2380, polar data, the 90 deg/-6 dB horizontal line-up is at 12.5 kHz, though with the 2380's wide tolerences, the M19/12 kHz XO should work fine if the M19's horn, woofer ctc spacing, cab width is same as the M19's and guessing without any design details the Werner's M19 XO for that matter, though best of course to discuss with him.

As for 416-8B performance at this XO point, find it hard to believe it has any real audio issues based on M19/12 kHz XO being the most popular of all Altec consumer & numerous (most?) DIY designs TTBOMK, not to mention my experience using it in numerous different speaker alignments, though for differing personal preferences/reasons have mostly kept XO's limited to Altec's 'textbook' 500, 800 Hz/2nd and used separate filters (various values of the 30923 + CD horn EQ), horn tweaks to fine tune them nominally flat ~full range or as required in room where possible.

That said, really need to measure or use digital EQ/TD to dial in a good horn/woofer summation in the desired listening window location.

[Spackler]

Hi GM, thank you for the informative links and useful answers.

Still trying to figure out the crossover point and slope but am leaning towards 800 or 1200 Hz

I was primarily steering away from the M19 cabs as I had Electro Voice Sentry IIIs before and wanted to try something that was a little taller and a bit less wide, partly due to WAF and also due to the fact I am slightly limited in how wide I can go in my room.

One more rookie question if you don't mind but how does one go about EQing a horn?

Clearly I have a lot to learn here so again, thank you in advance.

Greets!

What is the XO's point/slope?

Based solely on Altec 416-8B measured, JBL published 2380, polar data, the 90 deg/-6 dB horizontal line-up is at 12.5 kHz, though with the 2380's wide tolerences, the M19/12 kHz XO should work fine if the M19's horn, woofer ctc spacing, cab width is same as the M19's and guessing without any design details the Werner's M19 XO for that matter, though best of course to discuss with him.

As for 416-8B performance at this XO point, find it hard to believe it has any real audio issues based on M19/12 kHz XO being the most popular of all Altec consumer & numerous (most?) DIY designs TTBOMK, not to mention my experience using it in numerous different speaker alignments, though for differing personal preferences/reasons have mostly kept XO's limited to Altec's 'textbook' 500, 800 Hz/2nd and used separate filters (various values of the 30923 + CD horn EQ), horn tweaks to fine tune them nominally flat ~full range or as required in room where possible.

That said, really need to measure or use digital EQ/TD to dial in a good horn/woofer summation in the desired listening window location.

[GM]

Greets!

You're welcome!

I meant what is Werner's XO's point/slope or is it his version of the M19's XO?

OK, I only meant maintaining the M19's components acoustic relationships for using its XO.

As for taller, you're in my 'wheelhouse' since tower/column/TL and vented variants have been my preferred DIY box alignments, recommendations since the '60s, though in the case of using the M19's XO is you might prefer the horn tilted down somewhat since it's 'voiced' for low horn position.

Also, the M19 basically has a classic prosound box alignment to get the 'West Coast Sound', but for HIFI generally better to go larger, tuned to Fs, so a bigger cab doesn't mean a larger footprint if going taller and not too much narrower unless can go deeper.

As long as it's not too much narrower than the M19 it shouldn't audibly impact the XO's performance as proven by a DIYer that made his tall M19 the width of the 811 horn.

Anyway the 2380 is only 17.5", too narrow for a 15" woofer, so the 811's 18.5" (17" internal) width can be the narrowest known to work OK, though personally prefer Altec's 22.5" i.d. to allow it to 'breathe' a bit.

So, what horn centerline/floor height you want?

Compression horns have anything but a flat response, so typically need what's called CD horn EQ AKA frequency shaping filter, RLC network, 'tank' circuit, band-pass filter and maybe more for all I know as I'm not big/well educated on XO/whatever filter circuits, most times using passive 'textbook' XOs for high power as Altec began doing in the digital age and 1st order for low power HIFI/early HT apps and tweaking with CD horn EQ and sometimes zobels for impedance correction.

Anyway, the 2380 has a polar response very similar to comparable Mantarays, so for all I know it may need a custom XO to get the best overall blend, especially if you move away from the matching 90 deg point. I assume Werner knows, but only know him by reputation, so YMMV.

Note the well measured 511 response prosound par excellence inventor/designer Tom Danley did to highlight for me the offsets that I wanted to be able to easily explain to novices how these type re-entrant/reciprocating/'pattern flip' horns work. CD horn EQ flattens it out to ~3.5 kHz, then a by-pass cap around the electronics is sometimes used in HIFi apps to 'lift up' its HF to personal 'taste' (a 'word to the wise': in mine and any sane man with one or more women around should allow them to set the HF response > ~8 kHz).