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klh model 21 with problems...


bjornklh

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Im sorry to post something not strictly speaking as a speaker problem. however the model 21 is in itself a speaker with a radio built into it, the whole radio is the acoustic cabinet, so im not breaking the rules too much right. =)

so my question is pretty straight forward

it works but gets very few stations... is it worth fixing? the case needs resto as well real bad, im wondering if i shouldn't just get another one since they are pretty cheip...

also is there a way to hook up an aux input into these, like some how do a jumper inside the case between the tuner and amp section so i can hook up an aux input or a tuner?

thanks all for the info, if any. =)

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Im sorry to post something not strictly speaking as a speaker problem. however the model 21 is in itself a speaker with a radio built into it, the whole radio is the acoustic cabinet, so im not breaking the rules too much right. =)

so my question is pretty straight forward

it works but gets very few stations... is it worth fixing? the case needs resto as well real bad, im wondering if i shouldn't just get another one since they are pretty cheip...

also is there a way to hook up an aux input into these, like some how do a jumper inside the case between the tuner and amp section so i can hook up an aux input or a tuner?

thanks all for the info, if any. =)

Hi Bjorn

We've discussed this, but maybe these photos will inspire input from other members.

Although there is no Aux In on the 21, the tuner and amp are on separate PC boards and if someone knew what he was doing, it "should" be possible to add one, I would think. Remember tho, it will be mono. Then you woul need a selector switch, I think. Maybe a simple toggle on the front, between the speaker and the faceplate. Or on the back panel. You would also need an input jack. Again--back panel might work or replace the "Tuner Out" jack, which you will probably never use. Lots of room inside to work.

That poor reception could be some bad caps and/or alignment. The caps in the tuner are pretty easily accessible and dirt cheap so if you are handy with a soldering iron you might just try recapping.

Is it worth fixing? I have sold absolutely perfect, refurbished ones for $150, and I recently sold a real nice refurbished one for $100. Clean ones often go for under $100 on ebay. So you decide. OTOH, if you are going to add an Aux input you may want to cut up one that is not a pristine museum piece, because you will degrade its collectible value.

Here's another thought: Advent 400. This was Henry Kloss's next radio after he left KLH and it does have Aux In. I have a 400 and a 410 for sale if you are interested.

Good luck!

Kent

post-101828-1244672899.jpg

post-101828-1244673885.jpg

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  • 2 months later...
Guest David Goncalves

Kent - I didn't realize you had a clean scan of the KLH 21 schematic! Thanks for that, I've had a difficult time with the photocopies from Bill Turner.

I noticed something. The de-emphasis RC circuit has a time constant of 44 uS on the tuner output and around 22uS on the amplifier input (though I've found that HF response of the amplifier gives an effective deemph. of ~40uS). Odd!

David Goncalves

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Although there is no Aux In on the 21, the tuner and amp are on separate PC boards and if someone knew what he was doing, it "should" be possible to add one, I would think. Remember tho, it will be mono. Then you woul need a selector switch, I think. Maybe a simple toggle on the front, between the speaker and the faceplate. Or on the back panel. You would also need an input jack. Again--back panel might work or replace the "Tuner Out" jack, which you will probably never use. Lots of room inside to work.

Here's another thought: Advent 400. This was Henry Kloss's next radio after he left KLH and it does have Aux In. I have a 400 and a 410 for sale if you are interested.

Here's yet another thought: The Lafayette Criterion IV seems like a KLH clone. I have 2. Very nice cabinets--not like the Bauhaus-inspired Advent 400. Mono, but with an Aux input. A CSP member wrote "The 1969 Consumer Reports book I've got here rates the Lafayette Criterion IV (cat no. 3525w) as having better sound than the KLH Twenty One, and was listed at only $69.95 ".

Kent

post-101828-1251725873.jpg

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