Look at my new babies...Altec 846Bs w/EV Tweeters!

[Zilch]

I thought for correct Time Alignment the drivers need/should be on the same plane.

Nope, the acoustic centers in the same plane, all other factors being equal, and that typically means the voice coils are aligned vertically for time alignment in the horizontal plane perpendicular to the midpoint between the drivers. See Fig. 5A. in #190, below.

That's why dome tweeter baffles are stepped rearward in some designs, and horns are pushed forward in others. In 4430, the butt cheeks are ~1" in front of the woofer, and that's a shallow horn. In some of the theater systems, the horns are pushed way forward to achieve time alignment with the woofers.

As Tom points out, it's all about compromise. Clearly, many early horn designs didn't even consider time alignment. That's why delay is used on the woofers, to compensate for the offset. You can dial in delay and watch the notch at the crossover frequency disappear on an RTA. The amount of delay required will tell you the offset of centers from the measurement height via triangulation.

[Tom Brennan]

"That is why I would say move it forward."

Oh, the tweeter, yeah. I didn't follow you at first.

[Zilch]

Hmm... sounds like drilling is involved. No way to sit this on top or clamped on to the top of the horn? How much will the project run and is an external crossover needed... still very curious.

Yes, all that, maybe.

BMS tweeter's $99 new, 2407H a bit less on eBay, horns as little as $10, like for the JBL one shown below. Lots of HF horn options if you're not trying to squeeze it into such a tiny space. OASR, Engebretson, EV, Dayton, Emilar, Radian, others.

There's no room in Valencia to get it on top of the horn and still be in the cabinet.

In other systems, there's more options. Here's 2407H on the top horn. Time alignment's not the best, obviously:

[Aligned with the woofer, tho. Screw it. Sounds fine.... ]

[Tom Brennan]

Zilch---In my experience and opinion books sound better than cardboard boxes. ;-)

Also shown is how old PWK mounted his T-35 back when used a radial horn, 1950s I'd guess. Of course he was noted for ignoring time alignment.

[sourceoneaudio]

Or we have the no vibration, no slide foam pad custom mount.



J/S-S1A

[loach71]

Yes, all that, maybe.

BMS tweeter's $99 new, 2407H a bit less on eBay, horns as little as $10, like for the JBL one shown below. Lots of HF horn options if you're not trying to squeeze it into such a tiny space. OASR, Engebretson, EV, Dayton, Emilar, Radian, others.

No room in Valencia to get it on top of the horn and still in the cabinet.

In other systems, there's more options. Here's 2407H on the top horn. Time alignment's not the best, obviously:

[Aligned with the woofer, tho. Screw it. Sounds fine.... ]

Hey -- I miss the "cowboy Zilch" figurine -- what happened to him?

[Zilch]

Hey -- I miss the "cowboy Zilch" figurine -- what happened to him?

The JBL "action figure?" He got cropped outta that one. Heh.

HEY, what's that motorized vane in the PWK horn, a tremolo?

You'll note those boxes are GENUINE JBL....

Can you find all six JBL logos in that pic?

[scott fitlin]

HEY, what's that motorized vane in the PWK one, a tremolo?

[Tom Brennan]

I knew you'd pick up on that vane. I have no idea, maybe it was a mechanical equalizer, you'd adjust the vane to where you liked the tonal balance. I never saw such a thing.

[moldyoldy]

Similar to JBL 2407H (occasionally on eBay,)

http://www.bmspro.info/index.php?sho...10278&id=54358

We need a tiny horn to go with it, either in the 811 itself or the available space at the side, even if that means sliding the 811 over to make room. With the right dispersion pattern, it could be mounted at an inward angle at the side.

Somebody'll have to document the present geometry of the front horn/cabinet interface, elevation and plan; I can't tell from the pics...

Coax mounting sounds cool, as Tom said, in theory, that is. When you test the 811 with decent resolution, you'll find lots of peaks and dips, mostly from internal reflections, adding more wouldn't help anything, nor would altering the horn geometry. The grill and cab edges will diffract for a baffle mount, which might not be a bad thing. It must have even been noticeable with the 811, hence the foam.

Aside from damping the horn resonance, attention paid to the smoothness of the driver/horn transition is well worth the effort. So is removing the throat brace and molding the seams, but only if you're gonna keep 'em.

The logical and appropriate tweeter would be an Altec 3000B or H. Cute little 1/2" radials (B) or sectoral (H) that run out to 22kHz on a mylar W.E. microphone 'fram. Rare, working models rarer, and priced accordingly.

(Add/Edit; Was someone confusing the Valencias with the VOTT lineup a few posts back? I'm afraid they wouldn't cut it, even in a mini-mall plex. More self-serving spin on old marketing hype.)

Here's some old pictures that might help. I believe As and Bs (846s) were slightly different, but am unsure. anyway, verify the plan matches the app.

[moldyoldy]

I knew you'd pick up on that vane. I have no idea, maybe it was a mechanical equalizer, you'd adjust the vane to where you liked the tonal balance. I never saw such a thing.

Looks like a Leslie 2-speed motor stack there, but no belts or driven pully? :dont-know

[Tom Brennan]

Moldy--- Maybe a fella used it as an organ speaker with that vane spinning away?

[moldyoldy]

Could be. Several others tried to mimick Leslies, and some used spinning vanes in front of a cone driver. Reminds me of talking through an old oscillating fan at low speed as a kid.

[Shane Shuster]

Despite feeling like a magazine interviewer here tonight, I'm not gonna let you get away without telling us the conclusion. Have you found a more satisfying approach? Sounds to me like you put the DIY Altecs away, then?

If I just listened to 1960s and 70 rock and pop I probably would have kept using the Altecs. They have elements to them I like, but I know what I want my system to sound more like, and the Altecs were not it. I thought about adding a tweeter, and was already using subs, but then you have to step back and realize you basically have a 3way. Why use a general purpose horn with a phase plugged driver in a 3 or 4 way? I just did not see a point in redoing an Altec with modern thinking/standards. My current thinking is to let them be a fun, simple, speaker.

As for if I have found a more satisfying approach? Kind of. I know the sound I want but don't now how to get there so what I have done over the last 10 years is buy a speaker from each of the main types (ie, planar, horn, ect.) and use them each at least 6 months. I don't compare them to each other really. I just listen to what they each do individually and decide if it gets me closer to what I want. I like the vintage systems dynamics but don't like the directivity and leanness.

I currently have Tannoy system 1200s in my main system which are much closer to what I want. They still have some problems that need ironed out. (if it's even possible to do so)

[Zilch]

Thank you, Shane for your contributions to this thread.

Your candor has been refreshing, to say the least, and your information and opinions most valuable....