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KLH model 30 Rebuild


nothingfuture
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Hey all-

I've been (slowly) rebuilding some KLH model 30's I came across.

So far, I've recapped the crossovers, and replaced the RCA connectors with something more robust.

Everything's been going swimmingly.

Except that when I got the speakers, one was missing the tweeter.

My suspicion is that a cap in the crossover died, and the previous owner didn't hear any highs coming out of the speaker- and assumed (wrongly) that the tweeter was the cause.

As a result, I need a new tweeter- and while vintage sets come onto ebay from time to time, I'm not overly committed to a all-vintage rebuild.

So- are there any known contemporary replacements? I know about the whole AK Econowave thing, but I'd rather not buy new crossovers and whatnot.

Thanks a ton.

t.

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  • 2 weeks later...

You're likely to face the same crossover challenge unless replacing with an original driver.

Information I see suggests it's the same tweeter as the KLH model 6 and 17, rather common on ebay. Someone please correct me if I'm wrong.

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Hey there - I happen to have a pair of KLH model thirty speakers and am psyched to find someone else who may know a bit about them. They sound really good with a very old pioneer amp that I inherited with them for such a small speaker. Great lower end. I want to get a new amp and am wondering what would be a good choice. Would also like to replace the old school RCA jack on the back to update a bit. Did you pull the woofer and go in from the front to change the jack or can you take off the back somehow?

Thanks -

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  • 1 year later...

Hello KLH 30 owners,

I am in the processing of refurbishing a pair currently. The tweeter and crossover are being changed, however, so this is not really a restoration. After successfully completing similar changes on a 1976 pair of Smaller Advents this spring, I was very encouraged (especially by the strong, solid bass) and thought a similar strategy (although with different tweeters) would work well for the KLH 30s, which have similar design parameters (sealed box, full-range woofer, etc.).

To answer some of the questions above:

Disassembly - Remove the screws holding the woofer and the four on the tweeter to gain access to the innards. Leads to the woofer and tweeter were soldered, but the terminations on the crossover board are male tabs for female tabs on the driver leads - easy to remove. I left short pieces of wire attached to the drivers to avoid having to resolder on the driver itself.

RCA Jack Removal - Just did this last evening. The jacks are press-fit into the metal KLH name plate, which is held on by four nails, which look like rivets. Gently pry around the nail heads, then pull out with a small hammer or tack puller. Next you need to free the name plate sheet metal from the MDF using a sharp putty knife - there is a thin layer of adhesive. Clip the yellow and black leads and remove the plate and jack, then crush and pry the jack out of the plate, which I kept for reuse since it has the KLH logo, model number, etc. on it. You can then drill new holes for binding posts of your choice in the MDF above the plate. I am using the ex-RCA jack hole to mount an L-pad for the new tweeters. You could also out an inset for a cup-type binding post assembly as well,

New tweeter and crossover - I wanted to replace the OEM driver since tweeter technology has advanced greatly, and the 1976-Advent tweeters on the Smaller Advent were very mediocre. There are a great number of soft dome, metal dome, etc. choices, depending on your preference, sensitivity needed, and the size requirements. For the KLH 30, I was curious to try a ribbon technology, and bought a pair of Fountek 2.0, 5-inch, 7-ohm tweeters from Madisound. You need to use at least a second-order crossover design with a target frequency of 2000-2500 Hz to avoid unpleasant resonances with the ribbon structure that occur if you crossover at too low a frequency. A 3rd-order is even better, but with more reactance issues from the greater number of capacitors and inductors. The Madisound 14 AWG Perfect-Lay 1.0 mH inductor and a 4.7 uF Solen Fast Cap combo gives a 2nd order (12 db/octave, Linkwitz-Riley alignment) crossover frequency of 2500 Hz.

Woofer Run full-range - I noticed the original crossovers for both the Advent and KLH had the woofers running full range, and since they sounded fine, I did not change this design.

Reassembly - Reverse the process and install/wire first the input terminals/L-pad on back panel (leave leads long), then choose mounting hardware (I like new bolts, nuts and lockwashers, with Lock-Tite) and wire then mount the tweeter, then finally wire and re-mount the woofer, which cannot use separate nuts because you will not have access to the rear to hold the nut. I seal all openings with Silicone calk and also use a speaker sealing material, since this is a sealed box design. Any leaks will degrade bass performance. I also had filled in the old screw holes with Plasticwood to improve screw-holding in the crumbly MDF used.

Cabinet Exterior - I had already sanded and applied stain, then a rubbed linseed oil finish, and the qulaity of the walnut veneer on my Model 30s was very impressive. These are the best-looking speaker cabinets I have.

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  • 3 years later...
  • 1 year later...
On 10/1/2012 at 3:31 PM, rklute said:

Hello KLH 30 owners,

I am in the processing of refurbishing a pair currently. The tweeter and crossover are being changed, however, so this is not really a restoration. After successfully completing similar changes on a 1976 pair of Smaller Advents this spring, I was very encouraged (especially by the strong, solid bass) and thought a similar strategy (although with different tweeters) would work well for the KLH 30s, which have similar design parameters (sealed box, full-range woofer, etc.).

To answer some of the questions above:

Disassembly - Remove the screws holding the woofer and the four on the tweeter to gain access to the innards. Leads to the woofer and tweeter were soldered, but the terminations on the crossover board are male tabs for female tabs on the driver leads - easy to remove. I left short pieces of wire attached to the drivers to avoid having to resolder on the driver itself.

RCA Jack Removal - Just did this last evening. The jacks are press-fit into the metal KLH name plate, which is held on by four nails, which look like rivets. Gently pry around the nail heads, then pull out with a small hammer or tack puller. Next you need to free the name plate sheet metal from the MDF using a sharp putty knife - there is a thin layer of adhesive. Clip the yellow and black leads and remove the plate and jack, then crush and pry the jack out of the plate, which I kept for reuse since it has the KLH logo, model number, etc. on it. You can then drill new holes for binding posts of your choice in the MDF above the plate. I am using the ex-RCA jack hole to mount an L-pad for the new tweeters. You could also out an inset for a cup-type binding post assembly as well,

New tweeter and crossover - I wanted to replace the OEM driver since tweeter technology has advanced greatly, and the 1976-Advent tweeters on the Smaller Advent were very mediocre. There are a great number of soft dome, metal dome, etc. choices, depending on your preference, sensitivity needed, and the size requirements. For the KLH 30, I was curious to try a ribbon technology, and bought a pair of Fountek 2.0, 5-inch, 7-ohm tweeters from Madisound. You need to use at least a second-order crossover design with a target frequency of 2000-2500 Hz to avoid unpleasant resonances with the ribbon structure that occur if you crossover at too low a frequency. A 3rd-order is even better, but with more reactance issues from the greater number of capacitors and inductors. The Madisound 14 AWG Perfect-Lay 1.0 mH inductor and a 4.7 uF Solen Fast Cap combo gives a 2nd order (12 db/octave, Linkwitz-Riley alignment) crossover frequency of 2500 Hz.

Woofer Run full-range - I noticed the original crossovers for both the Advent and KLH had the woofers running full range, and since they sounded fine, I did not change this design.

Reassembly - Reverse the process and install/wire first the input terminals/L-pad on back panel (leave leads long), then choose mounting hardware (I like new bolts, nuts and lockwashers, with Lock-Tite) and wire then mount the tweeter, then finally wire and re-mount the woofer, which cannot use separate nuts because you will not have access to the rear to hold the nut. I seal all openings with Silicone calk and also use a speaker sealing material, since this is a sealed box design. Any leaks will degrade bass performance. I also had filled in the old screw holes with Plasticwood to improve screw-holding in the crumbly MDF used.

Cabinet Exterior - I had already sanded and applied stain, then a rubbed linseed oil finish, and the qulaity of the walnut veneer on my Model 30s was very impressive. These are the best-looking speaker cabinets I have.

Thanks for this guide. Super excited, just won a pair of these at local auction. They are coming in the original box so hopeful well cared for and the drivers are still good. Final price was 25.56, hope that is a decent price for these.

I know an old thread but am curious how the updated driver and recap sounded? Rklute, give us some details on how that tweeter sounds please. If i attempt will need to learn more about crossover building. 

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