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Altec Valencia Cabinet Mods

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Posted on December 10, 2009 at 12:14:19
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004



I've got this pair of Altec Valencia's that I picked up this summer. The drivers are nice. The cabinet was beyond hope. So I started to research these speakers. I measured the T/S parameters and did simulations on different cabinet sizes and tunings. GM provided some valuable info on this forum as well.

First I went to bi-amping. I found 1200 Hz to sound optimum at 24 db/octave (Linkwitz-Riley). KT-88 tube amplifiers top and bottom. Next I pulled the high frequency horns out of the enclosures, and closed off the opening with ¾” plywood, which was drilled to receive 4-3” id schedule 40 PVC pipe ducts.

I turned the enclosures upside down to elevate the 15” 416Z off the floor. The horn went on top. Each horn received an entire bar of Duc-Seal clay just above the vertical fins, 1/2 on top and half on the bottom.

And finally, I added a 3 cubic ft box to the enclosure. First I cut large openings into the removable back of the enclosure. Then I glued the new box to the back, covering the new holes. Then I replaced the back onto the box.

So I ended up with around an 8 cubic foot box, and the ability to change ducts at will. I will experiment around with this for a bit until I settle on the best tuning.

Then I will build the final cabinets. I’ll post my progress.

Comments and questions welcomed.

Regards
Les

 

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RE: Altec Valencia Cabinet Mods, posted on December 10, 2009 at 12:54:32
sootshe
Audiophile

Posts: 38
Location: Brisbane Australia
Joined: September 3, 2009
Looks like a good project. Can you give us some details on the drivers in this combo? Is the bass driver a 411? Horn type & driver? What crossovers are you using?
Thanks,
John

 

RE: Altec Valencia Cabinet Mods, posted on December 10, 2009 at 13:03:46
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
The horns are 811b, 806a driver. The mid-bass is 416Z. The crossover is an ESP circuit board I purchased.

 

RE: Altec Valencia Cabinet Mods, posted on December 10, 2009 at 13:12:30
sootshe


 
Cool....keep us posted on your updates.

 

RE: Altec Valencia Cabinet Mods, posted on December 10, 2009 at 17:17:38
Don M
Audiophile

Posts: 174
Joined: July 17, 2000
Les,

Can you comment on the difference between the 5 versus 8 cu. ft. cabinet?

When the initial T/S specs were determined it appeared that the 416 was suited for the smaller cabinet.

Thanks,

Don

 

RE: Altec Valencia Cabinet Mods, posted on December 11, 2009 at 02:05:57
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
Hi Don.

I'm still fooling with optimum venting. Simulations show the larger box rolls off earlier but goes lower. I seem to be detecting some heaviness in the male bass voice, which sounds like a bump in the upper bass. It's going to take me some time to figure out.

 

RE: Altec Valencia Cabinet Mods, posted on December 11, 2009 at 09:36:55
Don M
Audiophile

Posts: 174
Joined: July 17, 2000
Is it also possible to use a transistor and tube amp during your listening sessions. I think the output impedance of the amp will relate to the different cabinet volumes, if I understood the comments from GM. A tube amp would go better with the larger enclosure.

Don

 

RE: Altec Valencia Cabinet Mods, posted on December 11, 2009 at 09:48:19
Palustris
Audiophile

Posts: 1409
Location: Cape Cod
Joined: September 12, 2008
You are the only other person I know who has turned the box over, put the 811 on top, and a baffle in the hole where the 811 horn was. I did this about a decade ago and I listened to them for a while but traded the speakers for a H-K Citation II. They were my first introduction to Altecs.

I never got very fancy with the baffle, just used the opening size recommended by Altec. I made my own crossover replicating the Altec. One further point: the 802 driver does not fit well inside the Valencia cabinet as it is longer than the 806, but by taking the horn out of the cabinet you can go to the 802 driver.

 

RE: Altec Valencia Cabinet Mods, posted on December 11, 2009 at 15:55:53
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
Did you ever experiment with the 802?

 

RE: Altec Valencia Cabinet Mods, posted on December 12, 2009 at 01:08:55
GM
Audiophile

Posts: 568
Location: Georgia
Joined: April 26, 2000
Agreed, so a larger net Vb and/or lower tuning and/or damping the vents are the usual solutions.

GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

 

RE: Altec Valencia Cabinet Mods, posted on December 12, 2009 at 01:17:39
GM
Audiophile

Posts: 568
Location: Georgia
Joined: April 26, 2000
You did. ;^) Typically, 10-12 ft^3 MLTLs with tunings around Fs have proven to be the most popular DIY alignments of mine for the various 416s whether SS or tube PP driven. SET amps typically require somewhat larger cabs to go low.

GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

 

Altec Valencia Cabinets, posted on December 12, 2009 at 15:57:05
Interstage Tranny
Audiophile

Posts: 2733
Location: Eastern
Joined: October 4, 2006
I am following this thread closely. I have both Valencias in home, the 16 Ohm and 8 Ohm versions. The 16 Ohmer uses the compliment of drivers Les is using, plus I use the seriously good original N800F xover. So, what made these speakers so classic ? How can an undersized box sound so good, so huge ? How can it image so well ?

First, the original 16 ohmer trounces the 8 ohmer. The 8 ohmer uses ducted ports each side of the woof. The 8 ohmer uses a complex xover, with small iron-core trannies. So, not only does the 8 ohmer sacrifice efficiency, the xover slopes are far sharper in cutoff than the low phase shift 16 ohm xover.

The 16 ohmer, 846A, has the bass ports on each side of the horn; very important. Also very important is the close coupling of woof surround to tweeter mouth(front of horn). These close coupling methods, plus the low phase shift xover, yield the incredible imagery these Valencias are capable of setting up.

So, turning the box upside down and moving the tweeter/horn atop a molded wooden barrier(the old top or bottom molding flange) must have some immediate sonic differences, to be sure. Tweaking this new design will take time, and I am proud that you added more "box" in the rear; how resourceful...

When the horn is inside the box, attached to the box, it does not ring. But, lying it atop a box can bring out the worst in its' ringing. BTW, another tweeter mod to avoid is cutting the brass screen away from the driver mouth, unless you need a bright tweeter. An 802 is not recommended for usual home hifi. For a far away seat in a theater or barn, okay. But, for a home or garage, 802s sound sizzly. Duct Tack is nice, but these 811, or 511, horns need coatings or they need to be tightly attached, to minimize their inherent ring.

Play with the fore and aft arrangement of the horn mouth proximity to the woofer. Try a low slope xover, please. Usually, Valencias do not like toeing in, at all. They seem to image best when close to parallel, IME. Keep posting on this build of your new Valencias...

 

RE: Altec Valencia Cabinets, posted on December 13, 2009 at 03:40:14
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
Thanks Tranny.

In my final enclosure, I intend to bring the 416z up high and close to the horn. I turned the cabinet over to get the voice frequencies up off the floor; the horn is around the same distance from the 416z as originally.

I'll try them not toed in; something I hadn't considered.

The screens on the drivers were so full of crud I cut them away.

I can try a shallower xover, like 12db, however I am committed to bi amplifiying. Actually tri, I haven't brought the subwoofers into play yet.

I have tried 25hz tuning of the 8 cubic ft cabinets and it sounded as if the lower mids were pushed back 30 feet. Tapping on the cones yielded a ringing thud. So I added 4 pieces of 16"x 24"x 3 1/2" fiberglass to the fiberglass that was in the original enclosure. Tubby bass.

Then I substituted different venting at a Vb of 40 hZ. Together with the added fiberglass, it really sounds solid. Maybe I'll take one piece of 'glass out and try that as well.

Funny thing: with the 40hz tuning, when I tap one woofer it has that dead sound I think it should. The other has some thud.

What I am really looking forward to is a well braced baltic birch cabinet for the 416z and a sand-filled box for the horn.

I hope this happens in the next month of two.

Thanks for your insights.
Les

 

RE: Altec Valencia Cabinet Mods, posted on December 13, 2009 at 08:05:03
Palustris
Audiophile

Posts: 1409
Location: Cape Cod
Joined: September 12, 2008
Yes, I did end up using the 802Ds. I also covered the horn with Dynamat and removed the bug screen. These changes made a huge improvement in the clarity and freedom from artifacts in the sound. I eventually ended up with the big Magnificents boxes. I have been using them for a decade going through several other much more expensive speakers once in a while, but going back to the Altecs each time.

A few more points. Even with bi-amping you can replicate the Altec crossovers with new good quality coils and caps. The crossover for the tweeter and woofer can be built separately and still be exactly as Altec designed; each connected to its own amplifier. Even the best of the Altec crossovers can not come close to the freedom from artifacts that a rebuild using modest components can achieve. This reduces all the sizzle and hard steely highs and allows the 802 to really be heard clearly. It is the same reason to remove the bug screen. I have my Magnificents toed in so that the speakers are aimed at the listening position.

You will need to adjust the distance from the rear wall to ensure that the bass is accurate and firm while leaving enough space behind the speakers for the image to "bloom" with full depth of soundstage.

OK, now for a wildly OT comment: it is my building of small 1 and 2 liter racing engines for sports cars that made it impossible for me to leave the bug screen in the interface between driver and horn. In a racing engine the object is to cram as much fuel/air mixture into the cylinder for detonation as possible and to then evacuate the exhaust as rapidly as possible so that the next charge of fuel/air can replace it. In fact, the object is to get the exhaust gas flowing out to pull in the fuel/air mixture.

To achieve this, the air filter, carburetor (or fuel injection), cylinder head, and exhaust system must be as unrestricted, straight, and turbulence free as possible so as not to restrict the flow of fuel. Now imagine putting that bug screen in the intake side of the system or in the exhaust. What percent of the horsepower would be lost by that horribly restricting screen. I would bet probably 30% as a wild guess.

Now imagine that the compression driver and horn were an engine... Oh wait, they are an engine! They are an engine whose complete function in life is to move air in and out of that horn up to 20,000 times a second and more. Obviously we want that air moving in and out of that horn to do so in as unrestricted a manner possible so that the relationship between the horn throat and the compression driver is a perfect as possible for the most clear and accurate sound. While that may not be a perfect an analogy, there is no way I would put that bug screen in my racing engines and there is no way I would leave it between my horn and driver.



 

RE: Altec Valencia Cabinet Mods, posted on December 13, 2009 at 08:48:13
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
Thanks Palustris.

Actually, I did steal the Model 19 T network for the horns and place it across the HF driver. This gives some lift to the high frequencies. I tried baffle step correction for the low/mids with a bunch of coils and caps. I didn't like it much, though I may return to it after I get the tuning and stuffing issues resolved.

regards
Les

 

RE: Altec Valencia Cabinet Mods, posted on December 13, 2009 at 08:52:12
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004
Hello Don.

The larger box gives more extension. Not floor shaking bass, but more lf growl. What I am unsure of is if this extension comes at the price of inferior transient response.

Since I intend to use a pair of subwoofers (NHT 1259, air suspension, QT of 0.6), the extension may be meaningless.

If anyone has an opinion about this I would sure like to hear it.

regards
Les

 

RE: Altec Valencia Cabinet Mods, posted on December 13, 2009 at 15:14:37
Don M
Audiophile

Posts: 174
Joined: July 17, 2000
I would like to recommend that you also consider a mod that can be made to the Altec 811 horn.

Take a look at the post "Factors Affecting Sonic Quality" by Jack Bouska.

I added some dampening around the lips of my horns and also inserted some foam inside (a credit to Geddes). There was a noticeable reduction of the classic "horn honk" or color. However it should be noted that I was unable to measure the change since I do not own the appropriate equipment.

Altec partly addressed the problem with the foam inserted around the exterior of the horn on the Model 19.

You can easily test it out for yourself.


Don

 

Take out the bug screens..., posted on December 14, 2009 at 09:58:07
Qman


 
It does not make the driver brighter. You gain clarity and imaging. Made a bigger difference than damping the 811 horn.

 

RE: Altec Valencia Cabinet Mods, posted on February 1, 2010 at 12:50:28
les winter
Audiophile

Posts: 318
Location: Northern NJ
Joined: May 29, 2004



Well, after much experimentation, here is the cabinet I ended up with. the LF enclosure is baltic birch, heavily braced internally. Vents are 3" ID, 2" long. If it looks like a Model 19, well, I copied most of it. I intend to purchase a pair of 802-8G drivers to replace the Valencia 806's. The system is bi-amplified, 24db/oct LR at 1200HZ. I took the Model 19 HF shaping network and put it in front of the HF horn.

This thing has taken on a life of its own.

 

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