So, I just got 2 pairs of KLH Model Nines (Double Nines)...now let's get to work... - diyAudio
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Old 8th June 2015, 07:18 PM   #1
mazur is offline mazur  United States
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Default I just got 2 pairs of KLH Model Nines (Double Nines)...need some help.

Hello.

Well, just scored two pairs of KLH Model Nines, a pair of Double Nines They are all complete and in very good shape cosmetically. It belonged to a gentleman who bought them new way back and had it in his home for the last 40+ years. I have not tested them because I want to restore the electronics and crossover before I try anything.

The first problem I have is that the small pin that connects to the banana plug which connects to the positive of the bias supply has broken off in all panels and one is missing. Looks like the banana plug connection to the female on the box got corroded and stuck to the box, so when they tried to move the box out it broke off at the panel side. So first question:

- how can I replace the small pin that comes out of the speaker so that I can screw the banana plug male connector to the speaker.

- where can I find a replacement banana plug with the screwed hole on one side to tie to the panel.

I have not brought the panels home yet...will pick them up next weekend. But I did bring all 4 power supplies/crossover boxes. I saw a nice write up on how to melt the wax to de-pot the box and how to replace the selenium diodes for silicon chains as well as replace the bias supply capacitors for ceramic. Of course I'll also replace the caps on the crossover.

I'd like to get my hands on the schematics for the bias supply and crossover, so I'd appreciate any help.

I did read a few posts by Mr David Janszen and saw the services he provides on the Janszen web site. It's great to know that it is available, but I'm limited on my budget now so I'm trying the DIY route first. I'm familiar with the electronics side so I'll start there.

I can wait to get these great speakers back to their former glory.

Thanks.
Elias

Last edited by mazur; 8th June 2015 at 09:24 PM.
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Old 8th June 2015, 10:34 PM   #2
chrisb is offline chrisb  Canada
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picture of broken part?
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Old 9th June 2015, 12:36 AM   #3
mazur is offline mazur  United States
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Quote:
Originally Posted by chrisb View Post
picture of broken part?
Here they are:

This one shows one of the fairly good banana plugs and the other badly corroded:
WP_20150608_002.jpg

This other one shows one of the plugs in the transformer box.
WP_20150608_003.jpg

Thanks
Elias
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Old 9th June 2015, 10:55 AM   #4
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Quite amazing speakers, as I recall.

In the meantime, you might buy or build a high-voltage probe (200MOhms in series with 200KOhms which gives you 1000:1 reduction when measured across the 200kOhms). With a probe, assuming you are confident about working near high voltage, you can test.

I'd be lost these days without a mic and REW test software. And a Behringer DCX2496 digital processor to shape the sound and crossovers. Hard for me to picture how crude audio hobby work was before.

Ben
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Old 9th June 2015, 01:38 PM   #5
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Keystone Electronics makes the threaded banana plug; see p/n 659 or 6074-2 for plugs with 6-32 threads. These are available from Mouser (or Keystone can provide samples).
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Old 9th June 2015, 07:38 PM   #6
mazur is offline mazur  United States
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Quote:
Originally Posted by Mike Beck View Post
Keystone Electronics makes the threaded banana plug; see p/n 659 or 6074-2 for plugs with 6-32 threads. These are available from Mouser (or Keystone can provide samples).
Thanks Mike. Found it on Digikey as well. Will order soon.

Does anyone know the caps values in the crossover of the KLH Nine?

Thanks
Elias
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Old 12th June 2015, 03:54 PM   #7
mazur is offline mazur  United States
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Default Speaker Builder article on Model Nine rebuilding

Hi.

I heard about an old article on Speaker Builder magazine about rebuilding the Model Nines. Anyone has a copy willing to share/sell?

Thanks
Elias
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Old 12th June 2015, 04:23 PM   #8
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You can try contacting Mark Wilson at this address.
Mark was involved in the design of a lot of the KLH speakers.
If he still has any of the info yet.....


restorationATabsoundlabs.com
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Old 12th June 2015, 04:46 PM   #9
von Ah is offline von Ah  United States
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Wow, what a score! Hope you get them singing again, soon!
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Old 24th June 2015, 02:47 PM   #10
mazur is offline mazur  United States
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Restoration has started. Removed all banana plugs from the panels. Most had some kind of corrosion and rust. Ordered a whole new set for all panels.

Next, de-potted the first transformer box, replaced the diodes. Tested using clips and sounded great.

One down, three to go:
WP_20150623_001.jpg

Here is the multiplier board with the original selenium rectifiers.
WP_20150623_004.jpg

Now I have to figure out the right resistor to put in the AC input to lower the bias voltage to compensate for the silicon diodes. Don't have an electrostatic meter. Anyone willing to rent one?

Thanks
Elias
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