KLH Nine Electrostatic Speaker Rebuild Project

It was suggested by a fellow PS Audio Forum member I set up this page. It is not meant to draw attention to me, but rather to the artistry of the two “Davids” at Janszen Electrostatic Speakers and the history of the KLH Nine speakers. I have no great expertise in the subject manner. I am simply writing about my experience. For additional technical information please contact David Janszen at djanszen@janszenloudspeaker.com.

The first lesson I learned and want to repeatedly pass on is do not attempt and rebuild a pair of these on your own. Trust the professionals. Over the past year of owning these and meeting with David. I heard countless stories of butchered pairs he received after someone attempted to rebuild or modify them. The rebuild takes weeks if not months and requires skill to tear the panels completely down to their skeletons. For starters the 10 internal woofer, and one tweeter panel get new coatings and need new film stretched to the right tension. Sorry, but the rebuild process on the Original KLH Nines is labor intensive and expensive.

Supposedly, you can buy a new pair through the KLHaudio.com site. However, they are not built by David the son of Arthur Janszen the speaker’s creator. Older rebuilt Nine’s are still considerably less expensive then the $12.498 per panel cost of a new one. In searching the web I can find no evidence that any new KLH Nines have actually been built, despite their advertisement on the KLHaudio site.

This is one of my favorite stock advertising photos.

The speaker project started for me when I acquired 3 working pairs for a total of $3350 on 04/08/2018.

Working pairs when you can find them go from $750 to $2500 per pair depending on their condition. All three of my stock pair have worked flawlessly with both Prima Luna Mono Block 7 tube amps and Odyssey Kismet solid state monoblock amps.

Here are two pair set up in my audio room with the Odyssey monoblocks.

A short time later I switched to PrimaLuna tube amps and have done most of listening with them.

As of 02/25/19 two pairs have now been completed, the 3rd will remain in it’s stock form.

I will eventually get pics of the rebuilt Nines uploaded. Trust me they are beautiful, but a forewarning some restoration purist may be slightly offended. I have been spending the past few weeks dialing in the placement of the speakers and cabling. They do deliver on what was promised by David. Both the old and new speakers produce a surprising amount of bass, the rebuilds bass goes lower and tighter. More on that later.

So what goes into the rebuild?
Rebuild woofers
Replace original woofer diaphragms with modern film and coating
Apply proprietary coating to woofer signal electrodes to render them arc-proof
Modify tweeter mounting frames and replace tweeter panels with new JansZen z87
Damp upper treble backwave
Increase woofer damping
Add tweeter electrical network
Rebuild supplies
Replace selenium diodes in multiplier circuit with silicon diodes
Add crossover overlap compensation network
Modify transformer resonance damping network
Add current limiting resistor to woofer bias network
Replace binding posts with WBT nextGen
Replace proprietary mains inlets with IEC320 C14 inlet
Replace the signal and supply fuses, doubling the value of the signal fuse to reflect the
higher power handling capacity after arc-proofing
Replace phenolic supply interface terminal block with FR-4 (fiberglass/epoxy)
Refinish supply enclosure
Replace speaker panel bias wiring
Cut out area of front perforated sheet metal from ahead of tweeter panel and weld in
wire mesh
Revise ground connection of rear grill, refinish rear grill, disassemble frame and
reassemble using sturdier corner joinery
Repair dings and gouges in frame where possible
Refinish solid walnut frame with seven coats of hand rubbed Tung oil
Replace grill cloth with your choice of open weave, fine linen (samples provided ahead
of time for selection and approval)
Restore base/riser
Add acoustically transparent barrier membranes stretched on frames to both sides of
speaker panels to prevent incursion of particulates
Extended testing to ensure functional stability and compliance to specifications

What’s it cost?
$6.000 per pair, not counting sales tax.
Yes, yikes.
Yes, I had 2nd and 3rd thoughts.
No, I’m not wealthy.
Yes, I have been selling stuff like crazy to afford these.
Yes, there is still stuff for sale by me on this forum.
Yes, the Prima Luna Monoblocks pictured in later photos are for sale.
Yes, I have decreased dining out, have been repairing my old car to stretch out it’s life, amongst other things.
No, I have not been disappointed.
Yes, I would do it again.
No. I’m not done spending. Are you nuts I am an audiophile, more on that later.

A picture of the front and back sides including the transformers on the cleanest stock pair if Nines. I feel truly lucky, blessed to have found and to now own these.

Ignore that JBL Studio 530BK peeking out it just jealous.

The internal pictures, the panels have been removed.

Underside of Transformer. Everything is potted in wax . The bump can either reflect the speaker having been previously played too loud and for too long. Or, in this case someone did some slight modifications years ago to reduce the 800HZ bass hump the Nine’s were known for and then potted over it.

Transformer with wax removed.

A teaser photo.

David was kind enough to fix the Plaque shown above to the rebuilt KLH Nine’s. So cool, and more than I expected. I blacked out the 2nd David’s last name and my name for confidentiality.

Photos below:
Power supply before new parts installed.
Power supply with new parts installed, but not potted in wax.
Frame and protective mesh and film with tweeter window.
Completed speaker, with 10 woofers and one right center tweeter panel visible.
Close up of Tweeter panel.


Before the rebuild the woofer panels were a darker yellow looking and covered in dust, silty cigarette smoke remnants that you could sweep with your finger.

After rebuild panels have now been recoated, wires replaced, frames cleaned and the insides look almost sparkling new.

The newly oil rubbed walnut frame is beautiful this picture does not do it justice. This is real old fashioned wood, and not a wood veneer.

The back of a KLH Nine pair, notice they are now black with silver screws.
Beside them is a REL T7 subwoofer.

Finally, pictures of the completed KLH Nines. I elected to go with black linen grill cloth, instead of the lighter color linen of the originals which is no longer made.

A picture of the Nines under lower light with movable diffusers glowing blue behind them.
The color of light on the diffusers can be changed, or turned off.

I am extremely happy with how beautiful these look. At night when listening with the lights off or dimmed they visually almost disappear.

-The rebuilt Nines are now safer due to better grounding, and less likely to arc at high volume.
-They are now more immune to dust and dirt effecting the internal panels.
-They can now handle higher power Solid State amps, instead of the Vacuum Tube only amps recommended by some older Nine owners.

-The bass is now tighter and lower, treble is delicate, pristine and shimmers, instrument placement is more precise, vocals and midrange remains sweet and natural.
-Frequency response is now 40Hz to 21.000Hz.
-Despite their size they disappear, transport you to the venue, and do a great job of placing instruments on a wide and tall soundstage.
-They are now more dead quiet, with less background hash, despite the tube amps that are currently in use.

What may mean more to some then describing the sound is;
-The rebuilt Nines are now more power hungry.
-They sound better with 14awg power cords, instead of 18awg power cords even though they draw relatively little power.
-They are sensitive enough that they reward you with using good interconnects and speaker cabling.

I’m currently using Belden Iconoclast Gen II 1x4 TPC RCA’s, one pair of SPTPC, and one pair of TPC speaker cables. I tried some older Siltech speaker cable, but they lacked the clarity, bass and soundstage to name but a few things that the Iconoclast cables deliver.

At AXPONA I intend to shop for amplifier replacements. On my list so far are the PS Audio amps, and the Benchmark AHB amp. Eventually when I can afford it I will replace the Iconoclast TPC, with the SPTPC speaker cable, and still later replace the tin fuses in the transformers with SR Blue fuses. Past experience with other systems tells me this upgrade path will provide noticeable sound improvements. Further feeding my audio addiction.

I understand David Janszen will be demonstrating prototypes of his new Electrostatic Headphones at AXPONA this year. I heard them in his shop powered only by a cell phone. I was surprised at how loud they played, how dark and quiet the background was, how musical they were, and how good the bass was. In many ways I prefer them over my planar headphones, but admittedly I may be biased. The AXPONA website says David will be in room 8302.

I also understand Galen from Iconoclast Blue Jeans Cable will also be at AXPONA, and may be available to talk late Friday and Saturday near the PS Audio room. I hope to see him there.


This is great stuff…! Give us more please…!

I have added pictures of the completed KLH Nines, to my original post. Thanks for reading.


Fantastic restoration. I couldn’t imagine how long it would take to get the wax out and also the stains from nicotine smoke.

Restore and make it better than original, from the original designer!

Thanks, the two Davids at Janszen are artists and nice guys. I’m happy to show their work.

Thanks bro