adding a tweeter to Altec Valencia's.

[bottleneck]

Hi.

I have a pair of Altec Valencias. If you're unfamiliar with them, they can be seen in the '1975 International' catalogue in the library at this site.

I've noticed and read that their treble begins to cut off about 13khz.

It's my long term plan to add a tweeter or a supertweeter to the unit.

The intention is to run a seperate cable from the power amp, and crossover about 13khz, with a pot to attenuate the units level. Im open to either a stand-alone supertweeter, or putting a more conventional tweeter in a seperate box.

The problem I am having is picking the most appropriate drive unit.

Living Voice, and other DIY'ers often seem to use JBL 2405's, or a Gauss unit. JBL bullets seem to be used from time to time aswell. Fostex seem to do some drive units that would suit too.

The valencias have are 8 ohm and about 97-99db efficient.

Im hoping to get some advice on suitable HF drive units to select from. I haven't heard any of the above, and I will be buying blind.

Hope you can help!

Chris

[Zilch]

There's an article in the 2/05 Audio Xpress regarding using 2404H in Klipch, and some discussion of it here in the forum.

Put that on yer list, too. ;)

[spkrman57]

I would use a 1 ufd cap to a JBL bullet or similiar type efficiency tweeter horn. All you really want to do is add some "sparkle" to the top end.

The only time I would not recommend this is if you run higher wattage to speakers than low - med levels due to the 1st order crossover will not protect at "higher" levels.

Another thing is the crossover in you Valencia. If I recall correctly(from memory here), the 800hz crossover is a 2nd order Butterworth and a L-pad of the impedence of your drivers. The coils are probably okay, could be improved, but I would not because they actually worked pretty good with the drivers used.

2 ways to go on the caps, replace with "audio grade" or on the cheap, bypass them with MPP .68 ufd caps (I got mine from Parts Express) If you are on a budget(like me!!!), do the bypass caps to help the tired old caps out a little.

Just a little attention to the caps and rewiring will help the Valencia's out big time.

Room placement can be important also, I play around with 811B/511B horns and drivers. I have found reflective surfaces to the left and right of the horn's physical position can boost the mids a lot, but the multiple arrivals of the same signal can cloud the sound signature.

Just my opinions here, I'm sure others will chime in.

Regards, Ron

[Tom Loizeaux]

I think changing out the caps, or adding bypass caps might inprove the high end in your Valencias enough to satisfy you. I feel the 806 drivers with aluminum diaphragms put out a very nice high end. If you do add super tweeters, I really like the JBL 2405s, but you don't have to go to that good a tweeter for a little extra sparkle.
I have a pair of Valencias in my living room and find that the high end is OK...it's the very low end that needs help! Adding a helper subwoofer would make these very enjoyable.

Tom

[sonofagun]

I always found just adding one or two of the piezo units added plenty of high end "sparkle" - use them with some kind of tweeter cap (2-4 uf). Cheap and easy.

[Tweak48]

I noticed the same need for extension in my 846B Valencias as well.

The first effort was to replace the 30+ year old caps with Solens. That made a noticable difference. See attached photo. Small investment and easy fix.

The second solution I tried was to switch out the 806 driver with a 909 small format driver with the Tangerine phase plug. A dramatic improvement.

That did it for me. I found no need for further HF extension. Of course, I'm 50 years old and have been around big hi-fi and car stereo most of my life, so probably have cashed in my UHF hearing by now. I no longer have the Valencias (now running Summits more for the bass extension than anything else); what a properly set up 811 horn with the right driver can do is really amazing.

[bottleneck]

wow thanks for the help so far. keep it coming :)

the first and most sensible thing seems to be to change the caps. It looks like it only needs two per speaker.

Is taking out the crossover really really easy - just a couple of screws? You dont have to take the whole box apart do you?

I think I'd rather keep the existing compression driver and add UHF units - if it still needs it after the capacitor changes.


Thanks again
Chris

[Tweak48]

You don't even have to take out the crossover. Just pull the horn, and you'll have plenty of space to work with. I found it helpful to drop in an automotive trouble (work) light into the cabinet so I could better see what I was doing.
The black Altec caps have the values clearly marked on them. When you're ready to replace them you can unsolder one leg at a time (and even solder in the new cap in its place to avoid miss-locating it); or draw a simple diagram to remind you where things go.

You might find it an interesting exercise to do one box first, and then hook them back up to your stereo and do an A_B comparison with the balance control. I did that, and then invited family members in to offer opinions. They unanimously preferred the new caps.

You can pick up Solen caps at http://www.madisound.com (http://www.madisound.com/)

Good luck.

[bottleneck]

You don't even have to take out the crossover. Just pull the horn, and you'll have plenty of space to work with. I found it helpful to drop in an automotive trouble (work) light into the cabinet so I could better see what I was doing.
The black Altec caps have the values clearly marked on them. When you're ready to replace them you can unsolder one leg at a time (and even solder in the new cap in its place to avoid miss-locating it); or draw a simple diagram to remind you where things go.

You might find it an interesting exercise to do one box first, and then hook them back up to your stereo and do an A_B comparison with the balance control. I did that, and then invited family members in to offer opinions. They unanimously preferred the new caps.

You can pick up Solen caps at http://www.madisound.com (http://www.madisound.com/)

Good luck.



Hi.

I'm in the UK unfortunately.

I can get Solen caps though.

A chap I know runs this web based company. http://www.hificollective.co.uk/componentshome.html

I guess black gates or audionote caps would do aswell?

Im presuming you just take a few screws out to get the horns out then?

cheers
chris

edit: I notice the back of your horns have dynamat on them. Did you do this ? - make much of a difference?

[Peter Becker]

It is also better to change the original Cables against Kimber 4Pr.After you get better clearer Sound.

[bottleneck]

I've had someone change the caps, damped the horn with some dynamat, and have bought a pair of JBL 2405's to help the top end. These are going to sit on top of the valencias.

Problem is,

I have the DIY skills of a monkey, and about equal knowledge.

I do however have a local guy who will do all the soldering for me, he has just asked for a circuit diagram of what I want to do.

Just to recap, I want to bring in the JBL 2405's at the top end to help the Valencias out.

All relevant comments welcome :)

Thanks
Chris

["Duke" Spinner]

909 ... didya mean 902 ....

top end ... Beyma ...........

[Tweak48]

..............Man I miss this setup even to this day, and with running L-300 Summits in their repacement. Something about an 811/909 combo that is so real on human voices, it's eerie.

http://www.lansingheritage.org/images/altec/specs/components/909-8a-16a/page1.jpg

[GordonW]

The comments about power handling/excursion with a first-order crossover on the 2405 are well-worth heeding. I've seen shattered diaphragms on these. Not something to take lightly.

The crossover below, should take care of the problem. It'll act as a "quasi-first-order", starting its rolloff at about 13-14KHz, then "switch over" to an effective third-order down at about 4000-5000 Hz or so (increased rolloff, increased protection). Should be enough to take care of the driver, no problem, no matter what the power.

[bottleneck]

wow thanks Gordon, that really is helpful of you.

Hope you dont mind if I ask a question or 2? - They will be simplistic questions because Im not at all technical.

What I want to do is mount each JBL 2405 inside a little box. I want to put each little box on top of each speaker.

I want to wire a couple of speaker terminals on the back of these little boxes so that I can run them straight from the amplifier - just like a regular speaker.

What I was hoping to do is have a little ''volume'' type pot on the back of each to attenuate the JBL 2405's output. I should have mentioned that before, Im sorry.

Could this idea work with the circuit diagram provided?

Thanks again for your help, its very much appreciated.

Cheers
Chris