KLH Tweeter Application Questions for Service Manager

[Guest matty g]

Hi - My first question concerns the impedance for the tweeters used in KLH systems. A recent posting by KLH Service Manager stated that below ser. # 93000 there were two types of tweeters and above there was just the one type.

Were any of those tweeters 8 ohm units or were they all 4 ohm units? I read somewhere that some of the larger models used 8 ohm tweeters while the smaller models used 4 ohm units. Did they all change to 4 ohm after that serial #, or were there never any 8 ohm units manufactured?

Also, I have noticed in advertising that certain models have different tweeter sizes even though the frame is the same size. Was this something that was only done up to a certain production number and then stopped?

Thanks

Matt

[Guest matty g]

Hi -

I didn't mean to exclude anyone from this thread - by all means jump in if you have any info! I wrote that heading because I was curious about a post that Mark left a few days ago. It seems the tweeters in the KLH systems are as hard to figure out as the woofers. I always thought they were the same until I read somewhere that there were some tweeters that were 8 ohm. Then last week I saw a KLH tweeter on e-Bay that had a dcr of 6.5... pretty close to 8. I believe it was a pair that was from one of the larger models (not the Seventeen or Twenty). The advertising for those speakers raise more questions, too - since they claim to have different tweeter sizes. So, my questions still stand.....

Matt

[dynaco_dan]

Hi Matt;

I'm not an expert here by any means but here goes.

The 8 ohm tweeters will DCR at somewhere about 5.5 - 6 ohms.

A 4 ohm tweeter will DCR about 2.5 - 3 ohms.

The rating of a 8 ohm driver is taken at 1,000 hertz in a complete speaker system.

The tweeter, if crossing over at less than 1,000 hertz for example, may climb to a much higher and also a much lower impedance at higher and lower frequencies.

Henry seemed to do very well in only having developed almost a single tweeter, a single midrange driver and only a few woofers to cover their complete production line, quite a feat.

Speaks very well for that particular tweeter.

Speaks outstandingly of their consistant quality control.

It would be interesting, from a servicing point of view, which drivers were replaced most under warantee, the tweeters, mids or the woofers.

I know personnaly that here, locally, we replaced at least 100 woofers or even more of Dynaco A-25 woofers, to every one of their tweeters.

[Guest MarkAnderson]

AFAIK, the "real" KLH tweeter (as used in the Model 5, 6, 17, 20, 23, etc.) was the same for all models which used it. Some of the smaller KLH's, such as the Model 32, used a more pedestrian-looking paper cone tweeter, possibly sourced from CTS or the like.

[Guest molecules]

I have a 17 tweeter that is black vs the silver one on the 23's. Also seems to be quieter, though maybe they have aged differently.

Dave

[Andy]

As recently mentioned, in 1968 KLH listed different cone diameters for tweeters on these models......some were 1 3/4", others were

1 5/8" and still others were 2".

Models 12 & 6 had a 1 5/8"

Models 17, 20 & 12 had a 1 3/4"

models 22,24 & 26 had a 2"

Mising from the list was the tweeter size for model 23 ?

[KLHSvcMgr]

Hi Andy...

The serial number information pertained to only the Model 5 and Model 6 units. In the Model 5, the serial numbers prior to 93,000 used a custom built tweeter manufactured in our plant. Serial numbers above 93,000 used a driver made by Peerless, one of EAD's sister companies. The same situation holds true for the midrange. The low frequency driver was the same driver used in the Model 23, and was updated to eliminate the fire situation in both units, resulting in a recall for the original driver.

We used seven different versions of tweeters and I don't remember which ones were which specification wise. I do recall that they were not all the same impedance.

The serial number changes also applied to the Models 11, 12, 14, 15, 17, 19, 20, 21, 22, 23, 24, 25 and 26, to some degree.

The mechanical differences you mention pertain to the original, in house, manufactured devices compared to the out sourced devices, from Peerless. Electrically they were designed to the same specifications.

I wish my mind were better, but at 60, it gets a bit clouded.

Mark

>Hi - My first question concerns the impedance for the

>tweeters used in KLH systems. A recent posting by KLH Service

>Manager stated that below ser. # 93000 there were two types of

>tweeters and above there was just the one type.

>

> Were any of those tweeters 8 ohm units or were they all 4 ohm

>units? I read somewhere that some of the larger models used 8

>ohm tweeters while the smaller models used 4 ohm units. Did

>they all change to 4 ohm after that serial #, or were there

>never any 8 ohm units manufactured?

>

> Also, I have noticed in advertising that certain models have

>different tweeter sizes even though the frame is the same

>size. Was this something that was only done up to a certain

>production number and then stopped?

>

> Thanks

> Matt

[Shacky]

I picked up pair of 6's and both tweeters are dead. Recapping did not bring them back. I see a pair of model 20 tweeters on eBay. Are they an acceptable interchange?

My model 6 have screw in woofer and silver tweeter.

[Guest matty g]

>I picked up pair of 6's and both tweeters are dead.

>Recapping did not bring them back. I see a pair of model 20

>tweeters on eBay. Are they an acceptable interchange?

Shacky -

As I understand it, the Twenties and the Sixes had the same 4 ohm tweeters. Since you have to replace the pair you won't have to worry about matching one existing tweeter, however you might want to ask the seller to measure their impedance to make sure they are both the same.

Hope this helps

Matt

[soundminded]

As the owner of a pair of KLH Model 6s since 1965 I am obviously concerned. Now I own two pairs so I am doubly concerned. Until a few years ago, I'd never seen any acceptable substitute which would be a likely replacement for a KLH Model 6 tweeter, there just weren't any with an FR which extends low enough. However, I was intrigued by some Morel models such as this one, the MDT20.

http://www.partsexpress.com/pe/pshowdetl.c...tnumber=277-030

FS is 650 hz and response extends down to 1600 hz. Power handling is excellent and it should be more than sensitive enough. I'd think it might have to be padded down with an L pad and the capacitor value might have to be different.

I'd appreciate KLHSvcMgr's comments on this, not as a drop in replacement but as a candidate for bringing a system back from the dead with a little experimentation when there is no alternative.