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View Full Version : How do I bi-amp my Valencia 846B



hoosier1
06-16-2008, 06:28 AM
Folks,

I'm interested in biamping my Valencias. However, I need some step-by-step instructions and some recommendations for crossover, wire, etc.

I would be using a very good ss amp and a Decware CS84SE amp.

As far as I know, my speakers are completely stock with no issues. I do plan to add dampening material and cabinet bracing. Any other suggestions are certainly apprecaited.

Thanks for your help.

Jim

Fred Sanford
06-16-2008, 08:39 AM
Have you tried searching the site? There's been a ton of discussion on these speakers & crossovers over the last few years.

http://www.audioheritage.org/vbulletin/showthread.php?t=8789&highlight=valencia

http://www.audioheritage.org/vbulletin/showthread.php?t=5985&highlight=valencia

http://www.audioheritage.org/vbulletin/showthread.php?t=14690&highlight=altec+846

...and many more.

I wasn't part of any of the research or testing, but I think I remember one of the results being that there's some compensation built into the stock crossovers that isn't easily replicated in most of the active crossovers on the market, and folks went with upgraded passives and some also upgraded the horn drivers. Could be the 19s I'm thinking of.

Others will be along shortly...

je

Tom Brennan
06-16-2008, 09:45 AM
Disconnect the drivers from the passive crossover.

Install 2 sets of binding posts on the back and run wires direct from the woofer terminals to one set of posts and run wires direct from the treble driver direct to the other set.

Using an active crossover feed one amp to the treble driver and the other amp to the woofer. Stock crossover is 12db octave at 800 hz but not many active crossovers are 12db per octave, most are 18 or 24. But don't worry about it.

An outboard equalizer would be handy to EQ the treble driver, they need some treble boost. Instead of an outboard equalizer you can use a passive EQ circuit on the treble driver as seen hanging off the driver in my avatar, the system shown is bi-amped.

At a pro-sound shop you can find a crossover and an EQ and for not much dough either; a couple or three hundred bucks will do the whole shebang. Brands I've been well satisfied with are DOD, ART and Bi-Amp, there are many others.

Zilch
06-16-2008, 11:16 AM
Several members are using the Behringer CX3400 ($99 at Guitar Center or similar) for active biamping Valencia et al. Push the "CD Comp" button to EQ the 806 HF driver flat and mitigate its midrange "shout."

If you don't like the sound of that compensation, then build the adjustable version of the Altec "Bridged-T" filter used in the Model 19 crossover, which I have documented in other threads here.

The stock Valencia barely makes it out to 10 kHz. The most useable HF extension you'll reasonably get out of actively crossing and compensating 806 is to 14 kHz; if you want higher than that, you'll have to switch to different HF drivers.

Know also that the sectoral horns beam at high frequencies, and you'll need to be listening within a ~30° on-axis beamwidth window to hear the improvement. Generally, if you can't see the driver exit, the extended VHF response is not audible.

SMKSoundPro
06-16-2008, 02:31 PM
Yes, I agree.

In all of the work that was done on the Valencia's here in my shop, biamping was discussed, alot!

The box needs some additional bracing. Mainly from the baffle board to the back. Then tie from side to side, and finally top to bottom. Use a couple 2x2's, or something like it. Know that when you add lumber on the inside, you are subtracting volume of the air in the box. You may have to lengthen your tuning ducts.

Then, as was previously described, change the input connector on the back board. I use Speakons. Simple to use and I have lots of them from prosound stuff.

Install a protection cap in series with the compression driver. This is to block any dc current, and from possible turn-on thumps.

That's the basics. You may find an added layer of transparency in the vals when all is said and done.

I tried, with Zilch's help, the BMS driver solution with his compensation network. The result was a much smoother box. Not harsh or whiney.

Zilch posted the results of using a JBL LE85 (2420) comp driver bolted to the 811 horn and described very good results.

I biamp, or triamp and now quad amp all of my projects, but I work in more of the prosound dept.

If you choose to go with any of the above described paths, find a way to quantify your results using a RTA or some other test gear.

There is a great amount of info on the Vals, here. Start reading all of the posts. They are voluminous, and incredibly enlightening!!!

Good luck and welcome... "back my friend to the show trhat never ends"

The Valencia!

hoosier1
06-16-2008, 04:17 PM
Thanks folks!

You have given me some practical advice.

Since I'm not a DIYer per se, I guess all the info I read on this site plus what I read on Audio Asylum simply didn't alert me to actually what I needed to do. However, I can try what has been suggested here.

Please feel free to add further recommendations or advice. I certainly appreciate all!

Thanks again,

Jim