Jump to content
The Classic Speaker Pages Discussion Forums
Neal K

KLH 17 schematic?

Recommended Posts

Hello everyone,

  I am looking at a pair of seventeen that look to be in good shape. It's great that the surrounds are cloth.

They look inverted the way they are on the driver. My question is regarding the wiring to the filter. I've looked at it here and the one for the AR

model six. They have 3 positions. It looks like in 2 of the positions the signal goes thru the 2 then the 8 mfd cap. I've never understood the thinking behind

how it's wired. it looks like some of the signal goes thru both, and some goes thru just the 8. It's contouring thee top octave I guess. Can someone enlighten me because I'm going to grab them and replace the caps. No inductor the 10 inch rolls of after 1500. There is an 8 and one of those 2 in one job's. I'm thinking I probably will just listen and put in a single 10 mfd and possibly an L-pad. have to listen first. So what is the deal with the funny wiring? Thank's

Share this post


Link to post
Share on other sites

Does your Seventeen match this schematic?

KLH 17.jpg

It is best to replace the caps with like-for-like values. Redesigning a crossover is not a trivial task. The KLH 17 crossover is not a simple first order filter. It is a 3x cascaded, first order filter that has a switchable FR for the tweeter. 

Each position of the switch has a different contour for the tweeter FR. The 3 ohm resistors in parallel with the 2 uF caps allow a portion of the signal to bypass the cap and has the effect of lowering the attenuation at higher frequencies. The frequency at which the attenuation changes and the amount of attenuation is a function of the switch position. 

 

 

Share this post


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

Does your Seventeen match this schematic?

KLH 17.jpg

It is best to replace the caps with like-for-like values. Redesigning a crossover is not a trivial task. The KLH 17 crossover is not a simple first order filter. It is a 3x cascaded, first order filter that has a switchable FR for the tweeter. 

Each position of the switch has a different contour for the tweeter FR. The 3 ohm resistors in parallel with the 2 uF caps allow a portion of the signal to bypass the cap and has the effect of lowering the attenuation at higher frequencies. The frequency at which the attenuation changes and the amount of attenuation is a function of the switch position. 

I haven't opened it up yet. But it's a pair in very good shape and i don't think it's been modified or opened up. It's just a good idea to replace electrolytic capacitors after a half a century, god knows what they measure out at. I think I'll order some polypropylene caps from PE or Madisound. Maybe MDL caps at 12, 10, and 8. And 2 pairs of 2 mfd polys. The nominal crossover frequency is 1500 hz. I should probably not use anything higher than the 8 mfd series, as it is already about an octave lower than most of todays designs. I don't drive them too hard volume wise, I'd rather have the transient response and clean peaks with clean power. It's only a 6db/octave slope. Maybe I'll just order a pair of Clarity 8 mfd. I get a kick out of the "Capacitor freaks" who pay more for caps than they paid for the pair of speakers in the first place. I wonder if Solen and Mundorf pay these people. It is really funny. It's just an unusual circuit design with the 2 and the 8. I'm going to do a lot of listening then hard wire it either with or without resistors. If I do decide to use them I'll get the Mundorf metal oxide ones in an L shape. But there's nothing in life like real clean bass. Listening to classical or a Moog bass, it makes a difference that no 5 inch little box speaker can match. The vibes move the floor and walls and envelopes you in sound, and that is what it's all about, right? That's why were all here. Clean bass.  

 

 

Share this post


Link to post
Share on other sites
On 7/15/2019 at 2:50 PM, RTally said:

It is best to replace the caps with like-for-like values. Redesigning a crossover is not a trivial task.

What he said.

On 7/15/2019 at 5:30 PM, Neal K said:

That's why were all here. Clean bass.  

Not necessarily.

I've worked on a few KLH speakers with this xo: The Seventeens, Twenties, there may have been another 2-way that used that xo. I've used Dayton, Carli and a couple of other inexpensive film caps with good results. One 8uF and two 2uF per box. The Seventeen is a very nice speaker that reproduces the full range of music sounds/frequencies nicely.

Share this post


Link to post
Share on other sites

I've recently fixed up a pair of 17s, they sound (and look) really nice, but I wouldn't describe them as having heavy bass, but rather a nice rounded tone as JKent says. They project quite a bit though in my experience, the bass is more solid as you get further out from them.

I used Dayton caps and stuck to the same values more or less, using 2 x 2uf and 1 x 8.2uf. I keep mine in the Normal position on the switch.

I'm no expert but even more important, in my opinion, is to get the proper surround sealant to re-dope the cloth surrounds, which I acquired from Roy C on this board.

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.

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...