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KLH Model Twenty: purchased pair!


Giorgio AR

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After years of collecting AR speakers and for a long time wanting to get a pair of KLH speakers, I finally bought my pair of KLH speakers: I found a pair of Model Twenty in splendid aesthetic condition on the bay, including their original packaging boxes offered. at a good price.
Unfortunately, shipping to Italy and the related taxes have almost tripled the cost of the purchase, but if they arrive intact at my home, I'll be satisfied anyway!
They will be an excellent comparison with the AR2 and AR2x which I think are among the AR speakers the most similar in characteristics! These are the last photos I can insert, I can't insert the back of the speaker!

79429255_s-l1600(43).thumb.jpg.8740136609846fa4ff5edadf4f713c99.jpg197004111_s-l1600(44).thumb.jpg.ec1d0a312eb97fb295eb032441b6099b.jpg57521490_s-l1600(46).thumb.jpg.32b1b9ee8fc97a9a31f3d19bcc9b1bae.jpg1027578536_s-l1600(49).thumb.jpg.077768aee515094a125b2cdc2bd8553e.jpg

 

I look forward to the arrival of my splendid pair of KLH Model Twenty, trusting in an atraumatic journey of speakers and packaging from the USA to Italy !!

 

 

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From what they read up to now, even the KLHs will need the replacement of the capacitors which should be out of tolerance by a lot! When replacing the capacitors I think I will pierce the aluminum plate on the side of the RCA input and add the classic 2 AR screws for fixing the cables to the sides of the original socket, clearly moving the label with the serial number!

1748469553_s-l1600(48).thumb.jpg.d7eba34a24e8b3cb0e70801c556acd4d.jpg

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Congratulations on your new KLH Model Twenty speakers, Giorgio! 

The Model Twenty speaker was a 4 ohm version of the 8 ohm Model Seventeen speaker. It originally was designed for the Model Twenty compact music system, but was then later sold separately as a stand alone speaker. (The Model Twenty compact music system was my introduction to the world of “HiFi” when my father purchased one back in 1969 when I was a teenager, so I have very fond memories of that speaker…)

You are correct that the capacitors in the crossover should be replaced, and if you want to install binding posts instead of the RCA connector, that’s probably an improvement, too. KLH used binding posts in most of their speakers. As far as I know, the only KLH speakers that used RCA connectors were speakers associated with their compact music systems, like the Model Twenty and Model Twenty-Four.

The only other thing that you absolutely need to do, the one that you did not mention, is sealing the woofer fabric speaker surrounds. Since the Model Twenty is an acoustic suspension, airtight design, the porous fabric surrounds need to be re-sealed and airtight in order to get the best possible sound from the speaker. Don’t use anything other than “Roy’s Goo” to seal the surrounds. As far as I know, using another substance may seal the woofer so it is airtight, but will probably degrade the performance of the woofer over time.

Roy’s Goo used to be available from eBay at the “Vintage-AR” store, but does not seem to be available right now. 

Perhaps another member can chime in with advice on how to purchase this item.

I currently own, and have owned numerous sets of Model Seventeen speakers in the past. Even though I’ve owned both Model Twenty and Model Seventeen speakers, I can’t speak to how the two models compare in sound. There has been too long a lag time (25 years?) between my ownership of the two models and my memory is not anywhere neat that good. I would suspect they sound pretty similar. From what I have read, the tweeters and cabinets are identical, but the woofer differs, thus the disparity in rated impedance.

Right now, I am partial to the KLH Model Six and it is the main speaker in one of my audio systems.  If you like the Model Twenty, I would advise the Model Six as your next venture if you decide to collect another KLH specimen.

Good luck with your project, and I hope you enjoy listening to the Model Twenty’s. Please post with more photos and a report when you are done.
 

 

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16 hours ago, Norman Nicolai said:

As far as I know, using another substance may seal the woofer so it is airtight, but will probably degrade the performance of the woofer over time.

Roy’s Goo used to be available from eBay at the “Vintage-AR” store, but does not seem to be available right now. 

Perhaps another member can chime in with advice on how to purchase this item.

Other materials tend to stiffen the surround to varying degrees reducing compliance, and consequently deep bass response.

Larry/Vintage AR is away until the end of March. Forum members can always contact me directly, but I only ship domestically.

I've worked on many of these, and I agree with Norman's assessment. I would only add that the KLH 6 (my preference as well) is more like the AR-2a/2ax. The KLH 17 and 20 fall between the AR-4x and 2a/2ax with the 20 being more sensitive and a bit warmer sounding than the 17.

Roy

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On 2/8/2022 at 4:38 PM, RoyC said:

The KLH 17 and 20 fall between the AR-4x and 2a/2ax with the 20 being more sensitive and a bit warmer sounding than the 17.

Roy

Interesting take on the Twenties, Roy.

I've always read, and assumed as true, that the Model 17's were the better speaker because of the 8 ohm woofer and that they had better bass response because of that. This is the first time I've ever read that they sounded warmer. Roy, Is that based on your personal experience, on speaker reviews, or on something else entirely? If that's true, I'll start looking for a pair of Twenties to buy and refurbish for direct comparison to the Seventeens, provided that they are reasonably priced. For some reason, Twenties always seem to be quite a bit more expensive on eBay or Craigslist than Seventeens. Maybe, by way of an explanation for their cost, they are a bit warmer in sound.

But I digress and don't want to take over this thread. Perhaps a new topic for discussion?

 

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3 hours ago, Norman Nicolai said:

Interesting take on the Twenties, Roy.

I've always read, and assumed as true, that the Model 17's were the better speaker because of the 8 ohm woofer and that they had better bass response because of that. This is the first time I've ever read that they sounded warmer. Roy, Is that based on your personal experience, on speaker reviews, or on something else entirely? If that's true, I'll start looking for a pair of Twenties to buy and refurbish for direct comparison to the Seventeens, provided that they are reasonably priced. For some reason, Twenties always seem to be quite a bit more expensive on eBay or Craigslist than Seventeens. Maybe, by way of an explanation for their cost, they are a bit warmer in sound.

But I digress and don't want to take over this thread. Perhaps a new topic for discussion?

 

It was only based on some listening comparisons between re-capped cabinets a few times in the past. By "warmer", I did not mean that I found the 20 to have more bass response, just more influence on the higher frequencies. "Warmer" was also accompanied by what I felt to be less midrange definition, and on each occasion I preferred the 17 over the 20. There is a version of the 20 with a deeper cabinet, which I have never heard.

The crossovers are the same, so my guess is that the more sensitive 4 ohm KLH 20 woofer's effects (in the same volume cabinet) may simply be more noticeable in the higher frequencies.

Roy

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On 2/6/2022 at 3:22 AM, Giorgio AR said:

When replacing the capacitors I think I will pierce the aluminum plate on the side of the RCA input and add the classic 2 AR screws for fixing the cables to the sides of the original socket, clearly moving the label with the serial number!

Hi Giorgio. Congrats on the speaker purchase! I sent you some pictures privately but will also post them here for others who may want to work on some Twenties.

One word of warning regarding your plan: If you put the screws through the aluminum plate you need to isolate them to avoid shorting. KLH solved that problem by using rubber washers--one shoulder washer and one flat washer. Kind of a nuisance. But as the last photo below shows, this is exactly what KLH did with the Twenty +. As an aside, I've been asked to restore a KLH Twenty + compact system. Very cool Mid Century Modern stuff. If I take that project on I'll post pictures.

On my first Twenty restoration I added a terminal cup. But for that arrangement you should put caps over the RCA jack to maintain a sealed box. KLH used rubber caps on the unused jacks on the Model Twenty One radio but they usually got lost. I found some 5/16" screw protector caps in the local hardware store and those worked fine. I think the metric equivalent is 8mm. https://www.walmart.com/ip/Uxcell-5-16-inch-ID-Black-Screw-Thread-Protectors-Vinyl-End-Caps-20-Pack/751572364?wmlspartner=wlpa&selectedSellerId=571

On my 2nd Twenties I used a more elegant solution IMHO. I replaced the RCA jack with some dual binding posts like these: https://www.parts-express.com/Dual-Binding-Post-1-Red-1-Black-090-475  Fully insulated.

 

KLH 20 terminal.jpg

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P1110470.JPG

 

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Like JKent, I installed dual binding posts from Parts Express. I enlarged the holes to avoid shorting out the tabs extending inside the cabinet. The dual post came with a gasket to seal the cabinet. 

Also, like RoyC, I think the Model 20 are a fine performer. Placed side by side with my Model Six, I hear little difference. The Six goes deeper, but for most music, there is little difference. If I did not have the Model 6, I would be satisfied with the 20. Both sets are fully restored. I ran both the 20 and the 6 from a Denon POA-5200 amp (110 wpc @ 8 ohms). I have a pair of Model 17, but they are not yet restored so I cannot offer a comparison with the 17s, yet.

 

KLH 20 back panel 2022-02-14 small.jpg

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14 hours ago, JKent said:

Congrats on the speaker purchase!

Thanks Kent, unfortunately I got a Model Twenty in its cardboard box yesterday! The auction was for only one, but the translation of the Ebay Italia screen wrote pair !!
So now I only have one speaker ... an unfortunate mistake!
Given the advice and participation, I think I will buy an additional pair, with considerable additional monetary outlay, it is now a challenge, and so I will be able to have a stereo pair and the single can become a "central" speaker, connected to the McIntosh C28 preamplifier it owns. one output for central channel, dedicating an Electron Marrè monophonic amplifier with 80w of power !!
I'm not giving up on my pair of KLH speakers!

Giorgio

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Today I should buy an additional pair of KLH Model Twenty, I will notify you in a few hours about the outcome! I hope to buy them at a correct price, three KLH Model Twenty speakers will cost me about 600 $, over 2/3 of this amount corresponds to shipping and taxes ... my fault, next time I will be more careful about what I buy .. .

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What a shame! I looked at the original ad and the seller also wrote "I will be listing another Model 20 soon." Who separates a pair of speakers and sells them individually? But I'm glad you can use your center speaker output and enjoy 3 Model Twenties.

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2 hours ago, JKent said:

But I'm glad you can use your center speaker

Kent, after my adventure ended with the purchase of only one KLH Model Twenty speaker, (the seller is not at fault, he said that some time before a buyer wanted a single of two, the second, mine is next and the rest, no matter, I will update you after the couple's arrival in Italy and an initial small restoration), I was disappointed I bought a further pair of Model Twenty speakers, these from the link below ...

https://www.ebay.it/itm/313866354158

so we get to three, we hope to get a good pair with possibly a channel central (I have an 80w Electron Marrè monaural amplifier plus another Electron Marrè stereo amplifier, all have an output transformer!)), all connected to a McIntosh C28 preamplifier with center channel output.

This time it is certain that I got a pair of Model Twenty ... I hope.

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On 2/8/2022 at 10:38 PM, RoyC said:

The KLH 17 and 20 fall between the AR-4x and 2a/2ax with the 20 being more sensitive and a bit warmer sounding than the 17.

Roy thanks for the Model Twenty sound analysis and AR comparisons, you also said "a bit warmer sounding" which seems like a great comment to me.

I have a bottle of your cloth surround treatment and if needed it will be used to make the cloth suspension work properly: The ensemble woofer cabinet without the correct seal penalizes the low range a lot!

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3 hours ago, Giorgio AR said:

Roy thanks for the Model Twenty sound analysis and AR comparisons, you also said "a bit warmer sounding" which seems like a great comment to me.

I have a bottle of your cloth surround treatment and if needed it will be used to make the cloth suspension work properly: The ensemble woofer cabinet without the correct seal penalizes the low range a lot!

Hey Giorgio...I usually try to avoid posting my own subjective impressions, but I am always interested in others...especially fellow geeks like you :). Of course we will be very interested in the outcome of your project.

Roy

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On 2/14/2022 at 11:15 AM, JKent said:

Who separates a pair of speakers and sells them individually?

Well, I toned down my criticism. Turns out when I looked at that seller's ads to find your single Twenty I saw he was also selling single AR-4x empty cabinets. Just what I was looking for! He accepted my offer for the pair (I made sure he understood I only wanted them as a pair) and he then recalculated the shipping cost to save me money. A good guy after all. 

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Hi Kent, did you buy the empty AR4x cabinets for an original or Franken project? Hope the cabinets have the screws! Otherwise you find yourself with the same problem as me ... it seems that the rarest details are the screws. This seller also proposed (no longer appearing in auction) the cabinets of the Model Fifteen, a good basis for restoring a pair of these speakers.
P.S. from the photos of the purchased couple, the KLH badges on the grilles are missing, clearly if you still have replicas I will have to buy a pair, together (if you also sell them) with a pair of "customized" JKH that will go on the grids of the AR7 replicas: if this project will have the right realization, I owe it to your courtesy.

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Hi Giorgio

Funny thing about the Model Twenty speakers. I don't believe they originally had badges. But they do look better with KLH badges and I do have reproductions. I'll email you to discuss that. And I'm flattered you would put JKH badges on your speakers!

As for the AR-4x speakers, here's the story: My first speakers were AR-4x, purchased new in 1970. About 20 years ago (maybe 2002) I replaced the grilles but they didn't look right. That's when I discovered CSP and our friend John O'Hanlon (editor of the AR-3a restoration guide) guided me through not only getting the right grille cloth but also rebuilding the crossovers--my first! A few years later Roy helped me modify the speakers by installing Avid 100 drivers and crossovers. The Avids may be superior to the ARs (let the flames begin) but they were in horrible, disgusting, putrid vinyl "wood grain" cabinets 🤮 But the drivers are drop-in replacements for the AR-4x cabinets and the cabinets are virtually the same volume.

But now my AR-4x's are no longer. They're Avid 100s in nice cabinets. The ARs have strong sentimental value so I plan to restore the original drivers and will rebuild the crossovers with film caps and my new heavy-duty pots. So what to do with the Avid drivers and crossovers? When I saw empty AR-4x cabinets for sale I had to buy them!

Aren't you glad you asked? 😄

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Bravo Kent, excellent choice of AR4x cabinets to house Avid components, we have already seen some woofers and tw. AR4x in other, not original, but similar cabinets, the opposite, I think it's your very good project, the Avid will fit perfectly into well sounding cabinets. In this case the internal sound-absorbing material maintains the weight and AR characteristics?
Of course the double pairs of labels are in my wishes, and I will use them without adhesive, but with welded screws.

P.S. I also have two pairs of AR4x and one of AR4xa, the latter is in use, the other two pairs are sleeping in the closet.

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