Jump to content
The Klipsch Audio Community
Alexander

Zener diode alternative for AA's

Recommended Posts

Every set of networks I either built or rebuilt I removed the Zeners and fuses.  Never broke a Klipsch speaker in my life.  Those were back in the 70s when people used big power amps, didn't understand, and blew tweeters.  Remove them them and listen to music.

  • Like 2

Share this post


Link to post
Share on other sites
On 12/12/2020 at 4:14 AM, Alexander said:

@henry4841the end game will be replacing the OEM k77s with something like Crites tweeters. Just want to do things one step at a time. Had learn that the hard way years back in drag racing days.

 

When I first got my La Scalas, years ago, I checked the K-77s and found that there was a 2-3 dB discrepancy in volume between them, so I ordered a pair of Bob's CT-125 tweeters and Sonicap capacitors.  You're right, change one thing at a time, or you won't know which did what.  When the CT125s arrived, I tested and found them to be within 1dB of each other, which I suspect is better for stereo imaging.  After installing them, I noticed the immediate improvements in clarity and high frequency response.  That noted, I replaced the caps three days later, and they helped noticeably as well.  Twelve years later, the tweeters and capacitors still sound great, although the speakers are now in Surround position, having been replaced by La Scala IIs in main Left and Right position.

 

BTW, the new CT120 tweeters are said to sound even better than the CT125s.

Share this post


Link to post
Share on other sites

I changed my type AA back to type A no diodes. Never have any problems and I crank them all the time. I didnt know they cost that much but I would not replace them if they were a dollar a piece....lol

Share this post


Link to post
Share on other sites

I got some if you want them for free just pay shipping. Came out of my Type AA they dont wear out. The prices they want for them are crazy. Call me 816-769-9663 if you want them. 

Share this post


Link to post
Share on other sites
On 12/12/2020 at 8:26 AM, jimjimbo said:

I think Peter P. was just kidding.....

You mean the emoji after my statement wasn't visible?!

Share this post


Link to post
Share on other sites
54 minutes ago, ricktate said:

Rick you have to buy 25 to get that price. Mouser has some 10 watt ones but they are very pricey.  https://www.mouser.com/Semiconductors/Discrete-Semiconductors/Diodes-Rectifiers/Zener-Diodes/_/N-ax1mh?P=1yw7zctZ1z0z5fm&Ns=Pricing|0      Personally I think 10 watts is way overkill for a tweeter. Most listen with an average 1 watt or less with Klipsch speakers with some more on peaks. A 10 watt zener means a steady 10 watts not a peak. My original AL crossovers did not have the diodes and from what I have read most all AL's did. Must have been out of diodes when my crossovers were built or they were added after some warranty claims of blown tweeters. I have never blown a tweeter myself without the diodes. My kids did listening to music when they were outside the house. You will hurt your ears before you blow a 5 watt tweeter in your speaker sitting down in your room listening to music. Under normal circumstances you will not need the zeners or fuses even with the delicate old tweeter. I would not spend close to $100 for zeners but wait to if and when a tweeter blew and just put that money towards some Crites tweeters that are a perfect fit for the speaker with a much higher wattage rating. LaScala speakers were made for professional use using AA crossovers without diodes in loud settings. I am sure the diodes were added to prevent warranty claims. Must have not cost that much in quantity back then. 

Share this post


Link to post
Share on other sites

Yea I just saw that ,,then tried to delete the post...couldn't.  I have some if he needs them though. 

Share this post


Link to post
Share on other sites
51 minutes ago, henry4841 said:

LaScala speakers were made for professional use using AA crossovers without diodes in loud settings. I am sure the diodes were added to prevent warranty claims. Must have not cost that much in quantity back then. 

 

Actually, the A crossover (the one without the Zener diode) came before the AA.  I understand that there were tweeters blowing with the A crossover, so the AA crossover was then introduced.  I don’t think they sound much different, if at all.

Share this post


Link to post
Share on other sites
16 minutes ago, Islander said:

I don’t think they sound much different, if at all.

Yes they do, to me.  The AA is smoother and less bright, again, to me.

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, Islander said:

 

Actually, the A crossover (the one without the Zener diode) came before the AA.  I understand that there were tweeters blowing with the A crossover, so the AA crossover was then introduced.  I don’t think they sound much different, if at all.

The only significate difference between A and AA was a steeper slope for the tweeter, 3rd order instead of 1st order on the AA. Should provide plenty of protection if speakers are not abused without the need for diodes. The AA's are what I am using now in my LaScala's. 

Share this post


Link to post
Share on other sites

Comparing the two attached schematics suggests to this non-expert that there are differences other than Zener diodes.  Whether a difference can be perceived between Type A and Type AA is not the same as whether a difference can be perceived between Type AA with Zeners and Type AA without Zeners.  IMO, the presence or absence of Zeners is not perceptible.  Therefore, if unnecessary, remove them.

 

Type A (Medium).JPG

 

Type AA (Medium).JPG

Share this post


Link to post
Share on other sites

It looks like you guys can take it from here.  I just know that As have no Zeners and AAs do have them.  My 1974 La Scalas came with AA crossovers, complete with Zener diodes, and that’s all I’m actually familiar with.  I recapped them with Sonicaps a few months after I got them, and they’ve run happily ever since.  They’re now my surround speakers.

 

Some years later, I got La Scala IIs, which immediately became JubScala IIs, and they’re the main Left and Right speakers.

Share this post


Link to post
Share on other sites

The power rating is the diode power tolerance.  They limit voltage to 5.1, so (5.1 x 5.1)/8 = 3.25 watts to the tweeter.  Good for K-77s. 

 

I used a bulb and resistor as an L-pad for -1dB and tweeter protection.  The hotter the filament, the higher the resistance. 

  • Like 1

Share this post


Link to post
Share on other sites
On 12/10/2020 at 9:36 AM, Alexander said:

 

Was looking to build a pair of AA's from scratch and looking into the tweeter protection of the (for now) OEM k77's. Checking with Crites for zener diodes and found they cost $100 for the set. Being that this price is way out of the price range to work with what have some of you used as an alternative?

The OEM tweeters will be replaced early on so just can not justify the money spent.

 

Thinking of polytechnics but what value would be used if they are an option?

 

Perhaps a little off topic, but...

 

As I understand it, Klipsch went from the AA tweeter filter to the AK tweeter filter (elliptical) to further protect the K-77.  It's much steeper slope eliminated the need for the 

zener diode.  

 

Was this a cost saving modification?

 

Also, I hardly ever see discussions about this high pass elliptic filter.   Is it considered poor sounding?

 

Thanks, Mike

Share this post


Link to post
Share on other sites

 

DizRotus, yes I have SS amps that are all 100wpc minimum - but there is no chance of ever pushing anything close to the proverbial 11 o'clock dial position.


And thank you for the offers for diodes gents but I think we will go without like many of you suggested. If we do anything we would put a 1.25a fuse in line.

  • Like 1

Share this post


Link to post
Share on other sites

Didn't PWK do a Dope from Hope on this. I think the main issue was turn on/off transients from the older solid state amps. Fuses aren't fast enough for that, and neither are polyswitches. 

 

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...