KLH 20 tweeter question

[JKent]

I am fixing up a pair of Twenties and discovered one bad tweeter. Was the same tweeter used in any other models? I'll be scoping out ebay for a replacement. The Model 20 system is 4 ohm. Thanks for any info

Kent

[joelongwood]

I am fixing up a pair of Twenties and discovered one bad tweeter. Was the same tweeter used in any other models? I'll be scoping out ebay for a replacement. The Model 20 system is 4 ohm. Thanks for any info

Kent

I assume you've found the problem to be the tweeter and not a bad capacitor..........a very common problem in the KLH world. If the tweeter is indeed "bad," then a replacement is in order. I had a similar problem with a Model 17 tweeter, and after a lot of research I found the general consensus to be that the Model 23, 20, 17, 6, 5, and some others all used the same 4 ohm tweeter, even though the systems as a whole differed in their impedance ratings. In a similar vein, over at the AR section, it was recently discovered that the 4 ohm AR3 speaker and the 8 ohm AR2ax (pre-1970) used the exact same tweeter.

Hope this helps.

[JKent]

I assume you've found the problem to be the tweeter and not a bad capacitor..........a very common problem in the KLH world. If the tweeter is indeed "bad," then a replacement is in order. I had a similar problem with a Model 17 tweeter, and after a lot of research I found the general consensus to be that the Model 23, 20, 17, 6, 5, and some others all used the same 4 ohm tweeter, even though the systems as a whole differed in their impedance ratings. In a similar vein, over at the AR section, it was recently discovered that the 4 ohm AR3 speaker and the 8 ohm AR2ax (pre-1970) used the exact same tweeter.

Hope this helps.

Thanks joe

It is the tweet. I know the KLH caps are not too good after 40 years or so, and had just finished replacing the caps with new Dayton polys, THEN discovered the problem. Checked the tweet with an ohmeter and found it to be "open"--a break inside somewhere (?). Thanks for the lead on the other models. Keeping an eye out for ANY 4 ohm KLH tweeter.

On another subjuct...I'll be picking up those Rectilinear Mini IIIs we discussed in a couple of hours. So many speakers, so little room

Kent

[Andy]

As mentioned, most people feel that KLH tweeters can be interchanged from other KLH models, but it's worth noting that KLH listed different cone sizes on it's tweeters - Models 20 and 12 had a 1 3/4", Models 5 and 6 had a 1 5/8", Models 24 and 26 had a 2". I don't have a listing on models 17 and 23.

I've noticed differences in magnet sizes as well.

Andy

[JKent]

As mentioned, most people feel that KLH tweeters can be interchanged from other KLH models, but it's worth noting that KLH listed different cone sizes on it's tweeters - Models 20 and 12 had a 1 3/4", Models 5 and 6 had a 1 5/8", Models 24 and 26 had a 2". I don't have a listing on models 17 and 23.

I've noticed differences in magnet sizes as well.

Andy

Thanks Andy. We can count on you for the straight story on KLH. So if I don't use a tweet from a 20 or 12 I should probably replace them as a pair?

PS I told newbie evibeman that you are the KLH expert. He has a Model 15 turntable and the sheet metal is grey instead of the usual beige. Original? Or a replacement?

cheers

Kent

[joelongwood]

Thanks Andy. We can count on you for the straight story on KLH. So if I don't use a tweet from a 20 or 12 I should probably replace them as a pair?

PS I told newbie evibeman that you are the KLH expert. He has a Model 15 turntable and the sheet metal is grey instead of the usual beige. Original? Or a replacement?

cheers

Kent

The 17 uses the same tweeter as the 20. I've interchanged them, and they are identical.

[RoyC]

The 17 uses the same tweeter as the 20. I've interchanged them, and they are identical.

..and the 4 ohm KLH 23 tweeter is the same as the 17 and 20.

The KLH 5 tweeter has a higher impedance (dcr is between 5 and 6 ohms).

Roy

[dynaco_dan]

..and the 4 ohm KLH 23 tweeter is the same as the 17 and 20.

The KLH 5 tweeter has a higher impedance (dcr is between 5 and 6 ohms).

Roy

Hi Roy;

Now we are back to a few weeks ago, and previously, when there was at least a 4 ohm and also 8 ohm tweeter.

This week, Joe, a member, came out with, they used the same tweeter, 4 ohms, in a number of models.

Or am I getting too excited with that recent announcement regarding the classic AR 1 3/8" dome tweeter, now being only 4 ohms, always.

Maybe we need to do some further research into this.

[RoyC]

Hi Roy;

Now we are back to a few weeks ago, and previously, when there was at least a 4 ohm and also 8 ohm tweeter.

This week, Joe, a member, came out with, they used the same tweeter, 4 ohms, in a number of models.

Or am I getting too excited with that recent announcement regarding the classic AR 1 3/8" dome tweeter, now being only 4 ohms, always.

Maybe we need to do some further research into this.

Hi Vern,

All I know is that I have measured the tweeters in a number of KLH models. The 5's had a higher impedance tweeter, while the rest of 'em appear to have been the more "typical" KLH 4 ohm variety. The "4 ohm" tweeters have a dcr of 4 ohms, whereas the 5+ ohm dcr of the KLH 5 tweeter probably qualifies it as an "8 ohm" tweeter. It is clear there were some differences.

The magnets, appearance and overall dimensions were the same.

Roy

[Pete B]

I am fixing up a pair of Twenties and discovered one bad tweeter. Was the same tweeter used in any other models? I'll be scoping out ebay for a replacement. The Model 20 system is 4 ohm. Thanks for any info

Kent

I have a KLH tweeter that I think is from 20s, only one good in the

pair and it needs a home, you can have it. Carlspeak needed it at

one point but I think found another, I offered it to him, but if he's sure

then you can have it. It measures 4.3 ohms DCR.

I am looking for blown drivers from mainly AR and Advent speakers

for analysis. If you have any that you don't want that would be good.

Let me know if you want it.

[JKent]

I have a KLH tweeter that I think is from 20s, only one good in the

pair and it needs a home, you can have it. Carlspeak needed it at

one point but I think found another, I offered it to him, but if he's sure

then you can have it. It measures 4.3 ohms DCR.

I am looking for blown drivers from mainly AR and Advent speakers

for analysis. If you have any that you don't want that would be good.

Let me know if you want it.

Thanks Pete! You're a prince

Arrived today. I'll send out the blown KLH 20 tweeter and a blown AR 2ax tweeter. Sorry I didn't save some others but if I come across any they're yours!

Thanks again

Kent

[Pete B]

Thanks Pete! You're a prince

Arrived today. I'll send out the blown KLH 20 tweeter and a blown AR 2ax tweeter. Sorry I didn't save some others but if I come across any they're yours!

Thanks again

Kent

Good to hear Kent, it's good to see that they're going to good use!

Please check it out carefully I only gave it a quick listen.

This is what happened to the original KLH boxes, my son enjoys

these very much:

http://members.aol.com/basconsultants/klh_rebuild.htm

Best to you!

[beau]

Hi everybody, I'm a newbie ~
I've salvaged a pair of KLH 20's from my building's trash (outdoors in the rain!).
The woofers seem/sound OK, no tears, but there's no sound from the tweeters. Checked them both out, both with 4.5 ohms and a signal can be heard when their wires are hitched directly to amplifier's speaker outs.
So from what you guys have said, it looks like the caps are bad, right? Alas, it's a job to get inside & replace the caps, they're not super-accessible (as I'm sure you know) and I don't have a proper bench, but for free KLH's I'll hunker down and do the work (

Unfortunately I don't know much about electronics, and so I can't talk in technical terms, and I don't understand anything about the concept of Crossover. I can (usually) identify a capacitor when I see one, and I can wield a soldering iron OK, but I need an explanation of how to determine what cap to buy.

I've found this diyaudioandvideo.com page for identifying capacitors, but since I don't understand "Crossover type" I don't know what to do with the calculator.

Any help on this is greatly appreciated . . . thanks!

~ beau

[JKent]

hi Beau and welcome

First of all: The 20s are 4 ohm speakers. Not all amplifiers can handle 4 ohm speakers. An amp or receiver designed for 8 ohm speakers will have real problems with 4 ohms. If you tell us what you are using for amplification we can help.

It's not hard to get inside. You have to pull the front grille (it's attached with velcro) then remove the 8 phillips head screws that hold the woofer in place. Pry the woofer out. It's stuck in with some window putty that's probably hard by now. It will have to be replaced.

Behind the woofer is some cloth that is meant to keep the fiberglass out. Remove and save. Now put some gloves on and pull out all the pink fiberglass stuffing and save it in a plastic bag.

Now you'll get to the crossover. The crossover in the 20 is the same as the 17 and you will find a photo here: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5005#entry76699

Your crossover consists of 3 capacitors and 3 resistors. The resistors don't have to be replaced. The capacitors are probably black tubes with red ends and they are definitely bad. You may see only 2 of these but that's because one is a double. The capacitor values are 2uF (microfarad), 2uF and 8uF. There is also a switch and an RCA jack. One thing to consider: Most speakers are hooked up with binding posts, not RCA jacks. When I restored my 20s I installed binding posts.

So here's what you need to buy for 2 speakers:

4 of these (they are 2.2uF but that's close enough to 2) http://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-2.2mfd-150v/

2 of these http://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-8-mfd/

You may want to replace resistors, just because it's easier than saving the old ones. In that case get

4 of these http://www.madisoundspeakerstore.com/wirewound-15-watt/3-ohm-15-watt-wirewound-resistor/

2 of these http://www.madisoundspeakerstore.com/wirewound-15-watt/7.5-ohm-15-watt-wirewound-resistor/

If you want to install binding posts, order 2 of these: http://www.madisoundspeakerstore.com/terminal-cups/input-cups-nr-cup/

You'll also need something to seal the woofer when you replace it. Scrape off all the old dried up putty. You could use this

You can wield a soldering iron but be sure to use an iron and not a gun (they get way too hot). Replace one part at a time so you don't get mixed up.

One more tiny detail: If you do eliminate the RCA jacks they should be covered so the speaker remains airtight. You can get green rubber "screw protectors" in a hardware store or just tape over.

I'm attaching several photos. First are restored 20s with a terminal cup installed. Next is the woofer pulled. You can see the gray putty, the sheer cloth and the pink fiberglass. Third is an old crossover. You can see the black and red caps and in this case one has actually exploded! The final 3 pics show different ways to rebuild the 20 or 17 crossovers. Some use crimp connectors. The black capacitors are Dayton, from Parts Express. The yellow ones are Carli (the ones I linked to above). Some of the crossovers use the old resistors (brownish) while others have new resistors.

Ask any questions. Good luck.

Kent

[beau]

Hi JKent, thanks so much for the super-wonderfully detailed reply !!

My amp is a Teac A-H300 . . According to this audioholics.com thread, the Teac A-H300 is rated 35 watts per channel into 8 ohms and 50 watts per channel into 4 ohms.
I had gone inside before just through the tweeter hole, but, as you said, the crossover's pretty accessible through the woofer hole . . here's a photo (just so you're sure I know what I'm talking about! )

I do indeed have a soldering iron, little used these days but still functional.

<<Replace one part at a time so you don't get mixed up.>>

Yes, sir

I won't replace the RCA jacks, I've rigged up a coupla RCA plugs for the occasion.

I'll go ahead and order the resistors & capacitors, and will report back when the project is brought to a happy conclusion

Thanks again for such thoughtful help, it's much appreciated.

[JKent]

The pic is helpful. I'm pretty sure what you have is a double 4uF and a double 2uF. You can look at the capacitor body to check. Do not worry about the voltage--higher is better and the Carli caps will work.

The double 4 is wired with the 2 red wires together, making it an 8uF. Red and black wires will not matter with the new caps. Just treat those 2 reds together as tho they are 1 wire.

The other cap looks like a double 2uF and here the 2 red wires do NOT get wired together. The black is common. So you will take your 2 new 2 (2.2)uF caps and connect one end of each to the spots where the reds are connected, then take the other end of each and connect BOTH to where the black goes.

Caution: KLH stupidly made the plate under the crossover of aluminum, as in conductive metal. Be absolutely certain to insulate all your wires from the metal. You can use heat shrink tubing on the capacitor leads and/or plenty of tape on the metal plate. The 3 last pics in my previous post all show heat shrink tubing on the capacitor leads (the caps come with bare leads). If there's a Rat Shack near you they may have it: http://www.radioshack.com/product/index.jsp?productId=12656222&filterName=Price&filterValue=under+%243.99

Remember the wires will shift when you stuff the fiberglass back in so don't depend on just air space to keep the metal parts away from each other.

Kent

[beau]

Hi JKent, just wanted to let you know that the components arrived v quickly but I'm super-busy at the moment & I can't get to the speakers yet but will let you know all about the outcome as soon as it comes out!

[beau]

Hi JKent I

I"m (finally!) at the re-assembly stage

Question 1:

Replacing the old cap that's next to the switch, I want to be sure I understand correctly.

<<. . . looks like a double 2uF and here the 2 red wires do NOT get wired together. The black is common. So you will take your 2 new 2 (2.2)uF caps and connect one end of each to the spots where the reds are connected, then take the other end of each and connect BOTH to where the black goes.>>

Here's the old cap:

And here's the new 2.2uF cap, with two ends connected to go where black went. . .

I unsuccessfully googled how to tell + from -, so can I assume it doesn't matter? Or, does the little icon-in-the-square point to + or - ?

Question 2:

<<The double 4 is wired with the 2 red wires together, making it an 8uF . . .>>

Here's how it was :

Here's the new 8uF cap:

<< . . . Red and black wires will not matter with the new caps. Just treat those 2 reds together as tho they are 1 wire.>>

So, do I just put one wire, either one, to where the joined reds used to go, and the other to old black's connection?

Just trying to be absolutely sure before I go to soldering

[JKent]

Question 1: Film capacitors are non-polar (aka bi-polar but not manic-depressive )
Question 2: Yup

Good idea: "measure twice, cut once".

Kent

[beau]

Hi Kent ~

Success! Yay!

Plus there's drama!! As I was screwing in the last woofer screw the electric drill slipped and punched two holes in the cone!

After screaming for about an hour or two, I applied some tent repair rubber glue

How good do the speakers sound? They were free, judge for yourself!!!

Many thanks for your help!!!!! :D

[JKent]

Plus there's drama!! As I was screwing in the last woofer screw the electric drill slipped and punched two holes in the cone!

After screaming for about an hour or two, I applied some tent repair rubber glue

Glad you were able to fix that! It's funny (well, not funny. More like ironic) but when Bill LeGall reconed my Cizek woofers, he installed gaskets on the outside. When I asked why he explained that even experienced speaker guys will do exactly what you did and the gasket stops the bit before it hits the surround.

I love electric screw guns but it makes me think: Use a plain ol' screwdriver to be safe.

Anyway--Happy listening!

Kent

[beau]

Oh, forgot to mention . . instead of polyurethane foam for gaskets, I cut out circles from an old pair polartec pants . . much thinner than the heavy polartec jackets