Driver replacement for Altec Valencias?

[Plink]

Hi folks...just picked a very nice pair of Altec Valencias from a very nice member here and I'm curious about a driver replacements for the horn so that I can get better HF response.

I just read a long and amazing thread on improving HF response for Valencias and it was suggested to use BMS 4550 or BMS 4552. Are there any others to consider? I was also advised to try Beyma and was told they were better than BMS. Looking for a quick drop in and improvement.

I drive my Valencias with a 300B SET amp which is plenty of power. Sound is very nice but I'd like something smoother and with better HF response. The rebuilt crossover is at 1.2 khz. I need to find out more about this crossover and am investigating.

I also have Model 19s but I will be listening to the Valencias while I work on the 19s.

Thanks!

[Zilch]

We will need to know whether they are 846A or 846B Valencias, specifically whether the 806 drivers are 8 or 16 Ohms.

Also, 1.2 kHz is not standard, so the details of the crossovers are important. Do they provide high-frequency compensation?

The most direct route to what you want to achieve using the stock drivers is to active biamp using Behringer CX3400 and push the "HF Comp" button, but that will only provide limited HF extension, as 806s cannot provide the HF performance of your Model 19s:



Here's how they perform with the stock crossover:

[Plink]

Hi Zilch, they are Altec Valencia 846B and the 806A drivers are 8 ohm per visual inspection. Reads on outside: N800-8K but this, of course, referred to the stock crossover there. The new ones are at 1200 hz and have a zobel network on the woofer, as I am told.

Here are some photos of the rebuild. Also, I have an email to the builder and am waiting on details. Thanks!

[Plink]

Hi Zilch, here is what I found about the crossover:

"Back to the crossovers, yes, I raised the crossover point to 1200hz, the stock crossover went down to about 780hz for the horn and about 1700hz for the woofer, pretty strange overlap, I did a 12db at 1200hz for both sections, I think it sounds better with less California sound (midrange emphasis). I'm going from memory on those old crossover points, I'd have to have the original cap values to verify them. Raisinf the crossover point to 1200 also raises the power handling to about 100 watts.

On the Zobel, it was tuned for the 416-8A woofer inductance, that's the LE figure for the driver, an Altec 416-8B or 416-8C could also be fine. The crossover just has the Lpad, no other compensation was done, I don't know what state the woofer alnico charge is in so if they lack bass at all they could be discharged some, I'd try swapping your model 19 woofers for laughs and see if there's a difference. "

[withTarragon]

Plink, Regarding the layout on the crossovers, there may be a couple of concerns.

1. The 2 inductors should be well separated from one another and not right next to each other. Also they should not be pointed in a parallel direction. IOW they should be a "right angles" to one another. Usually the layout for inductors should be guided by some measurement equipment.

2. The inductors appear to be mounted using a metal handle. Please use a magnet to find out of the metal is ferrous. IOW if it is attracted by the magnet then do not use it for a mount. Use brass instead.

I am surprised no one has caught these details.

Good luck,
-Tom

[sbjacob]

Plink, Regarding the layout on the crossovers, there may be a couple of concerns.

1. The 2 inductors should be well separated from one another and not right next to each other. Also they should not be pointed in a parallel direction. IOW they should be a "right angles" to one another. Usually the layout for inductors should be guided by some measurement equipment.

2. The inductors appear to be mounted using a metal handle. Please use a magnet to find out of the metal is ferrous. IOW if it is attracted by the magnet then do not use it for a mount. Use brass instead.

I am surprised no one has caught these details.

Good luck,
-Tom

Good call I also would have gone with Solen inductors.

[Plink]

Tarragon...thanks for your input

1. Looks like Altec aligned their inductors the same way. Did they determine it wasn't an issue or am I missing something?

2. I'll have to open things up tonight and see if they are metal.

[Baron030]

The Altec inductors are iron cored, so as a result they are not prone to inductor cross talk like air core inductors are.

Here is a link that explains what inductor cross talk is and how to minimize it.

http://www.audioholics.com/education...osstalk-basics

Baron030

[Plink]

The Altec inductors are iron cored, so as a result they are not prone to inductor cross talk like air core inductors are.

Here is a link that explains what inductor cross talk is and how to minimize it.

http://www.audioholics.com/education...osstalk-basics

Baron030

Ah, I see and makes sense. Thanks. I will have to remount these and this should take care of issue 2 also. Glad I started this thread.

[Zilch]

I believe those conduit clamps are plastic. If so, not an issue.

I'm thinking about the rest of it.

What are the capacitor and inductor values, and the Zobel resistor? Also, which is the Zobel cap?

It looks like he made a symmetric crossover at 1.2 kHz, whereas N800-8K was asymmetric to tame the 806 mids, which he didn't understand, but even that didn't do it well enough. See below.

Even if we fixed that, 806-8A does not have the requisite HF extension.

I have an idea that I'll try to check out for you yet today. The 8-Ohm woofer simplifies this....

[sbjacob]

I believe those conduit clamps are plastic. If so, not an issue.

I'm thinking about the rest of it.

What are the capacitor and inductor values, and the Zobel resistor? Also, which is the Zobel cap?

It looks like he made a symmetric crossover at 1.2 kHz, whereas N800-8K was asymmetric to tame the 806 mids, which he didn't understand, but even that didn't do it well enough. See below.

Even if we fixed that, 806-8A does not have the requisite HF extension.

I have an idea that I'll try to check out for you yet today. The 8-Ohm woofer simplifies this....

Was wondering what the DCR of the inductors are on this network?

[Zilch]

Here's the adjustable 8-Ohm version of the Altec 30923 bridged-T HF comp circuit lifted from the Model 19 crossover, and the performance of three alternative drivers that play VHF on M19. Build that circuit and add it on after your existing Valencia crossover. Like Model 19, you'll adjust the two L-pads, to achieve the flattest or most pleasing balance, the new one being the equivalent of HF adjust:

[Zilch]

If you're really ambitious, here's my version of the Model 19 crossover with the HF separated from the LF, and the original, bottom, courtesy of the Markwart website:

[Plink]

Zilch, I'll have to find some time to remove the crossovers. With quick look, I cannot see the values with them attached. So, you're saying I should just put in a model 19 crossover and then try the BMS drivers? Or, keep my existing crossover, add the compensation and BMS, and let the chips fall where they may? Thanks. Btw, the inductors are mounted using plastic and not metal although they are mounted the same angle...which I will change.

[Zilch]

Zilch, I'll have to find some time to remove the crossovers. With quick look, I cannot see the values with them attached. So, you're saying I should just put in a model 19 crossover and then try the BMS drivers? Or, keep my existing crossover, add the compensation and BMS, and let the chips fall where they may? Thanks. Btw, the inductors are mounted using plastic and not metal although they are mounted the same angle...which I will change.

I am saying, since you already have some Model 19 crossovers on hand, install Selenium D220Ti drivers ($90 a pair) in your Valencias and play them with the M19 XOs. If that does it for you, then build the HF comp circuit and add-on to your existing Valencia XOs.

No good? Titanium diaphragms too harsh in the VHF? Try a pair of DE250 drivers, then, which have Kapton diaphragms. We know BMS mylar works, but these are less expensive options. Also, if you like the performance on M19 XOs better, I've provided the info necessary to build them or my "improved" version of them.

We still need the info on your crossovers; perhaps there'll be additional suggestions, but your question was what driver options might work, and I've presented data on three that I happen to have on hand. I don't have any 811B horns, just 511As, but prior experience tells me 811B will perform about the same.

If you want to stick with Altec drivers, then you'll have to acquire those used in Model 19 to achieve VHF extension, which means Tangerine phase plug 802-8G or 902 whatever, with vintage "lite" diaphragms, preferrably, but those aren't without their own issues, either, and not cheap.

I assume you've found both the Valencia "Babies" thread and Skywave's 9844-8B one, where we tested out these options....