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KLH Model Eight Radio Restomod


JKent

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I'm kind of a Model Eight nut, and over the years I've bought and restored about 100 of them. I don't do the real sophisticated electronics--for that I take them to Bristol Electronics. My work consists of refinishing the cabinets, replacing the grille cloth if needed, replacing all of the capacitors and vacuum tubes.

The Eight was a true high fidelity radio, with a separate acoustic suspension speaker. Originally they used twin 3" drivers left over from a previous project. Back in 1959 the audio consultants Bolt, Beranek & Newman had a project to equip the Senate chambers with high quality individual speakers for each Senator. So BB&N went to KLH and Kloss designed a speaker but the project fell through, so the speaker ended up in the Model 8 radio in 1960. Henry was a frugal guy and wasn't going to let excellent drivers go to waste but apparently when they ran out of those Kloss switched to a single 4" driver, the ubiquitous "twelve point five" driver that was used in so many KLH speakers.

I'm getting to the end of my inventory and running short on speakers so I built this reproduction that might be called a "restomod". I've seen some pretty cool restomod cars, like a 1960 corvette that looks original but underneath it has 4-wheel independent suspension, disc brakes, a honkin' big crate engine . . . but I digress.

So here's the restomod. A few years back my brother-in-law made a new solid walnut cabinet for the electronics. Recently I found a cabinet maker who built about 6 speaker cabinets for me. The faceplate is original and the radio itself is a fully restored original. The speaker drivers are dual 3" Tang Band W3s. I do have some 12.5 drivers but wanted to try something new. Grille is new 10-count Irish Linen. Grille badge and plate on the back of the speaker are reproductions.

The added bonus is an AUX input that allows one to play MP3s, CDs, etc. through the Model Eight's tube amp. I had built some of these as an external box, similar to the outboard Phono/Tape box KLH made back in the day. The built-in one can be seen in the upper left corner on the back. There's a 1/8" TRS jack, a 2-way switch and a TRS cable that plugs into the "Multiplex" jack on the back of the Model Eight. There's no need to unplug that cable--the switch selects the internal tuner or the external source. My circuitry consists of some resistors and a capacitor to sum the Left and Right signal from the external source and feed a mono signal to the amp.

I sold the radio to a fellow KLH enthusiast who wrote "Wow! That’s all I can say. This radio is not only a dream, it’s probably the only radio I’ve ever had with no low-level noise in the background of our local classical station. It beats a 1956 Telefunken Opus I have that has six speakers and is the size of a garage."

I love when that happens 😃

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Nice work, JKent!

Curious. How does the Model Eight sound compared to Henry’s later creation, the Tivoli Model One  tabletop radio? I’ve never heard a Model Eight but have a couple of Model One’s. I used to keep a Model One on my desk and listened to it throughout the day at work before I retired. Not great at high volume but thoroughly enjoyable at low to moderate listening levels. 

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54 minutes ago, Norman Nicolai said:

Curious. How does the Model Eight sound compared to Henry’s later creation, the Tivoli Model One

Well I have a real bias in favor of the Model Eight. I also have a Model One and several KLH Model Twenty-Ones. Thing is, FM reception is lousy here in the Appalachian Mountains of NJ so any radio listening is done over the interweb.

Disclaimers aside, I think a properly working Eight is excellent but a Model Twenty-One may challenge it. Especially the less-popular 21/II. The Tiv is OK but not my first choice.

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  • 3 months later...
On 8/4/2021 at 10:28 AM, JKent said:

The added bonus is an AUX input that allows one to play MP3s, CDs, etc. through the Model Eight's tube amp. I had built some of these as an external box, similar to the outboard Phono/Tape box KLH made back in the day. The built-in one can be seen in the upper left corner on the back. There's a 1/8" TRS jack, a 2-way switch and a TRS cable that plugs into the "Multiplex" jack on the back of the Model Eight. There's no need to unplug that cable--the switch selects the internal tuner or the external source. My circuitry consists of some resistors and a capacitor to sum the Left and Right signal from the external source and feed a mono signal to the amp.

Hello! I recently purchased one of your aux adapters. I would love to incorporate it into the radio like you have, maybe on a rainy day. 

Regardless, I've become quite obsessed with this radio as well. My first purchase was intended as parts but I went ahead and preformed a full recap, replaced the neon bulb and freshened up the cabinets and she preforms quite well, aside from the fine tuning not working. 

I was pretty content but not long after I saw one listed that included a second speaker. I have read quite a bit about the model 13, but nobody ever talks about just the model 8 with a second speaker. Have you come across these? I'll be curious to know if the schematic is similar. If two speakers can be hooked up, wouldn't that technically be an 8 ohm load (assuming the speaker is 16 like I've read)

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Hey Beave,

Thanks for the purchase. I'm sending a PM regarding your desire to install it in the Eight.

Too bad about the tuning cap. Those are unobtainium and I've relegated more than one Model Eight to the "parts donor" shelf because of a bad tuning capacitor. One suggestion: Make sure there is a gap between the center tuning knob and the larger tuning dial. They can get pressed together and then the friction causes them to turn as a unit. It's a long shot, since you've had yours out of the cabinet, but worht a try.

As far as the speakers go, I don't think KLH ever published impedance specs but here's what I can tell you:

  • The original 3" drivers have a DCR of about 8 ohms and they were wired in series, so the speaker assembled has a DCR of about 15 ohms (ish). No filter in these.
  • The later "twelve point five" driver was installed alone, also no filter. They have a DCR of about 8 ohms.
  • The extension speaker was exactly like the radio speaker but had a volume pot on the back and a special flat plug that was sandwiched between the main speaker's plug and the jacks on the radio. I have a few of the extension speakers but some had their flat plugs cut off and bananas installed so they could be used as main speakers.
  • You can achieve the same goal of adding an extension speaker by using stackable banana plugs.

I think the extension speakers I have all have the dual 3" drivers. Don't know if KLH made extensions with single 4" drivers but yes, installing 2 speakers in parallel will lower the impedance. Apparently the tube amp can handle a wide range of impedance.

Kent

 

extension spkr plug (3).jpg

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  • 2 weeks later...
On 11/23/2021 at 12:54 AM, LeaveItTubeBeaver said:

I recently purchased one of your aux adapters. I would love to incorporate it into the radio like you have, maybe on a rainy day. 

If any CSP member wants one of the built-indevices, send me a PM. They ONLY work with a KLH Model Eight but it's pretty cool to be able to play a cell phone's MP3 library through the Model Eight.

Kent

aluminum adaptor resized.jpg

aluminum built-in wiring 1 resized.jpg

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  • 1 year later...

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