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AR3A with KLH 20 System


Guest avs3259

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Guest avs3259

Does the KLH Model Twenty stereo system have sufficient power to drive a pair of AR-3A speakers? The impedances match (4 ohms). Thanks.

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As long as your listening is done at a moderate level, you should be fine. But you may want to consider the fact that Henry Kloss, designer of the KLH 20 system, most likely equalized the amp section of the 20 to mate well with the Model 20 speakers. A frequent poster (Bold Eagle) on the Vintage Asylum forums said this was the case. I don't think you would do any damage if you tried the AR3a's.......just keep the volume at sane levels. Let us know what you hear. :D

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Hi there;

I do feel that it is necessary to fuse the AR-3A's now, as there is a very high likelyhood that the amp will clip causing a blown driver.

A Bussmann FNM 1 1/4 amp slow blow was the recommended size, way back when.

Littlefuse FLM 1 1/4 amp slow blow is the equivalent.

Perhaps because of supply and prices, fast blow fuses are cheaper and more readily available.

Slow blow fuses about $5 - 6.00 each, plus fuseblocks, about the same price.

Fast blow fuses, about $2 - 3.00 per fuseblock and $.50 a fuse.

Heathkit/AR-3A speaker kit used a 3 amp fast blow fuse in a chassis style fuseholder.

I have used a 1 amp fast blow for decades, blowing the occasional fuse of course, when overdoing it.

In the interest of protecting our old classics drivers, perhaps a 2 amp fast blow fuse might be a better choice, today, rather than the 3 amp.

One can try anything without fuses but if a single fuse will save even a single tweeter, at $25.00+/- off ebay, there is that option.

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>Does the KLH Model Twenty stereo system have sufficient power

>to drive a pair of AR-3A speakers? The impedances match (4

>ohms). Thanks.

4-11-07 *:30 PM

Hello again to all CSP members.

I’ve been away tending to domestic affairs, which of course have delayed any AR dreams of restoration from happening, but that’s another story. This ‘rant’ is in response to driving an AR-3a speaker with adequate or

lesser than adequate power as the case may be. First off; in response to my dear friend “Dyna-Dan”, for sure he’s correct about the fusing issue. Fuses have permitted my speakers to live these past 35 plus years. Having said that, if I may repeat myself, and state as I have before here on CSP?

”AR speakers demand high power regardless of the model in question”. Here’s a comparison of sorts: When I bought my first car in 1967, a ‘Midnight Blue’, 1964 Chevy Impala with a 283 cubic inch, 2 barrel carb, that little sweet motor that I felt was all I needed to be happy and for all intents and purposes I was, until in 1971 when I bought a 1970, 350 C.I. Buick Lesabre, which certainly put down my ideas of adequate power from the ‘Imp’ and it really let me learn that I was wrong about my little 283. Fast forward to 1984. At this point I happened to be extremely lucky and bought a 1973 Buick Riviera which included a standard 455 C.I. motor (that's 7.5 litre for you metric guys) that had a ‘top-motor’ rebuild done to it, 4 barrel carb, 3 speed ‘turbo-hydra’, over-sized tires and a total ‘freshening’…

Need I elaborate? O.K. This motor was the ‘living-end’ in terms of sheer out and out, balls to the wall power, scary at times, (I’ve also been a passenger in a mint 1970 Chevelle with a 454, fully-worked, full blown with a blower on top, extra large valving, crank and pistons, with 2 – double-pumper Holly carbs on top, a 4:42 posi-rear and a tricked 4 speed manual tranny, full shields and fat wheels). The funny thing here; I had realized this same eye opening experience when I went from my little Dynaco ST-120 amp to my Phase Linear 400 amp in 1974.

It’s not just realistic volume levels we’re talking about here, but ‘head-room’ (does anyone remember that term?) and dynamics. Thinking back, it was the same as going from a 283C.I. motor to a 455 C.I. motor. Certainly a V8 is a V8, but after that confirmation all similarities ended. In terms of ‘petal-to the-metal’ the little V8 didn’t and certainly couldn’t ever match the 455 Buick big-block (this motor was also used in G.M ’s big-truck -like 40 foot motor home of the early 70’s-that motor home being the most beautiful ever built in present times), this 455 had even more torque & power than the 500 C.I. (8.2 litre) Cadillac motor of similar years. But even in terms of simple ‘cruising-speed’ along with sheer smoothness the smaller and bigger motors were worlds apart. Idle smoothness was so apparent with the big block as certainly was the total scene in terms of ‘raw’ scary power (my Riv and I were the fastest guys from 40 to 70 miles an hour on the old F.D.R. from 23St. to the Battery Tunnel, and on to Brooklyn.

With my “Riv”, simply motoring down the street was a lesson in power to ‘be-hold’ as was the switch to a higher power amp, and all it provided to the music and experience of listening. Now I must confess if I had the ‘moula’, the smolians, bucks or what-ever, I’m still searching for 2 Phase Linear D-500s’ for my four stacked LSTs’. But nonetheless from what little research I did on a low power amp as you describe- you’re missing the whole point here regarding vintage AR speakers, especially AR-3as’.

Make the move, enjoy the change and buy some sort of low cost perhaps used high power amp and then you will realize what vintage AR speakers are all about. Be it an Adcom, Phase, or even a no-name amp-from Par-s-Exp—s, a Kr—l, C’J’, ‘Clas e’ , Bryst-n,or Boul-er. Get in gear and enjoy 'the music' with a high power amp and listen to how music should be enjoyed. I’ve known this for over 35+ years, ‘catch-up’ will-ya!

This whole thing is almost the same as making love to a very beautiful and experienced woman, as compared to a hometown and in-experienced girl. I’ve done plenty of both of those sort of things too- there’s no comparison.

Do you get my point, no? Well force your mind’s imagination and your body to see another sort of day and experience, with a wonderfully different and unique sunset and a complete appreciation for it all.

My point is finally made clear, thanks for your indulgence!

Respectfully, Frank Marsi

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I do not think this is a good match at all. In fact it's a very poor one for a number of reasons. First the KLH model 20, a table top all in one package unit does not have nearly enough power to even begin to suggest what a properly functioning pair of AR3as is capable of. AR's recommended minimum available power at the time was 25 watts RMS per channel. Even this is too modest. At the time of the introduction of AR3 which had the same woofer, this was a fairly powerful amplifier. Today you would find only a handful of high fidelity audio amplifiers or receivers which could not deliver substantially more power. The KLH model 20's amplifier was probably rated at about 5 or 10 watts per channel and it may not have had sufficient low frequency capablitiy to produce the prodigious bass AR3a is capable of even at low volume. AR3a like its predecessor AR3 is a very difficult load for many amplifiers to drive because its impedence is so low, possibly below 2 ohms at some frequencies. This can cause marginal amplifiers to be damaged. The turntable will also likely produce considerable audible rumble with AR3a and will be prone to acoustic feedback as well. I would not worry about damaging the tweeters with this amplifier, it just isn't powerful enough. These KLH package units were wonderful systems considering their price and the era they were produced in and I have one, I think a model 18 in my basement somewhere which has one blown amplifier channel (I got it for nothing from a dealer of used equipment who said if someone doesn't take it, it goes in tht trash.)

If money is a problem, a good choice would be a used high quality solid state receiver or amplifier from about the mid 1970s to around the mid to late 1980s. I've got several of them myself and those I bought on the used market cost very little. For instance, I bought a perfectly functioning Pioneer SX 959 for 10 dollars at a garage sale. It puts out 85 wpc and could easily drive a pair of AR3as to high volume without distortion. There are many models from Pioneer, Marantz, Sansui, Kenwood, JVC among others. A good manual turntable if you need a turntable is also a good idea. I'd choose a model from Thorens like the TD 125, or an AR turntable if you can find one. Get your hands on an old Empire and you've hit the jackpot (I've got two.) Most of the older automatic record changers are not suitable but if you must have one, I'd go for a Dual model which is belt driven. These can also usually be had for about $100 or less.

By the way, be very careful of Home Theater (HT) receivers. Many are not recommended for use with speakers below 8 ohms and could be damaged by AR3a. Also, many have power bandwidths only specified to 50 hz which means they likely will not be able to produce the deep bass AR3a is capable of even though they may have nominally rated power of 100 wpc or more.

Good luck.

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In discussing the model 20 with Andy on the KLH message board, I learned a thing or two about it and the mismatch may not be quite as bad as I had feared and suspected. The Model 20 puts out 50 watts IHF which I assume means 25 watts per channel with both channels driven at the same time. This translates into 17.5 watts RMS per channel which is not the 25 AR recommends but is considerably more than I suspected. The model 20 was apparantly their most powerful and elaborate all in one system of that era. The model 20 speakers are also 4 ohm version of the model 17 so you are probably safe on that score too. And another bright note, the turntable is a low rumble version of a Garrard model with a synchronous motor, not the comparable stock model sold at retail which is much poorer. Be cautious. If you hear distortion, back off on the volume control. Fusing the tweeters in not a bad idea either as others have suggested.

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I am not familiar with the KLH 20 system, but I agree with others who indicate that the 3a prefers substantial power. I had been driving mine with a 120 wpc Yamaha receiver, and was easily able to send the receiver into clipping on (relatively) loud passages. The speakers are much more comfortable with more power.

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Guest matty g

Hi -

Please bear in mind that the bass control on the Model Twenty is not like your average bass control. I'm not shure of the exact ratio, but for every few degrees past the 12:00 position that you advance it the bass is increased by large amounts, which greatly increases the risk of clipping the amp and sending direct current to the speakers. I wouldn't recommend using the Model Twenty to power the 3a's, it's just not what it was designed for.

If you are fortunate enough to have a working set of 3a's, I would suggest picking up a nice vintage Pioneer, Marantz, Sansui, Kenwood or other similar such receiver rated at 60 watts or higher. I've been using a Pioneer SX850 to drive my 3a's at 65 watts per channel, which was quite sufficent. I did just upgrade to a Marantz 2330b at 130 wpc, which may be overkill, but better too much than too little.

You don't have to spend a fortune to get one of those nice vintage receivers, or go with seperates such as Adcom (they make a great 60 watt power amp that is perfect for 3a systems). Underpowering speakers is a sure fire way to destroy them. Trust me - I've done it.

Matt

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I'm not sure where I saw it but it might have been in a report by Julian Hirsch. The AR 12" woofer can handle impulse power of over one kilowatt! It's astonishing, at least it was to me especially in light of the materials available and in common use at the time of their manufacture. The very low impedence can cause amplifiers to clip at well below their nominal power rating so it may be a little misleading that your 120 wpc amplifier clipped. There is no doubt that even more than 50 years after its introduction, the AR 12" woofer still stands near the top in performance of low distortion extended range low frequency sound reproducers. This is a commentary on both the ingenuity of Edgar Vilchur and the lack of skill of his competitors even generations later. How fortunate for us that we are among the few who recognize these gems among the weeds when we see them. Many others pass them up even at their rediculously low prices to choose far lesser equipment instead, leaving them for us.

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Guest SteveG

Good discussion. All the comments about more power for headroom are entirely valid. It depends on how you plan to use the speakers and what material you plan to listen to. If you are listening to string quartets at low volume the KLH 20 may be fine. But if you have listening material with substantial bass content and want a moderately room filling volume then more power is a must.

I have a pair of updated 3a's (AR 11's) as main speakers in the family room with a 5-speaker surround setup for movie watching. Had been running this for some years through a Pioneer receiver rated at 100wpc rms but this was of the light weight variety of receiver that effectively split the amps somehow when using more than just the 2 stereo channels. So I always kept volume low. The Pioneer receivers with home theatre capability allow you to direct all bass content for all chanels to selected speakers, and I do this to the mains so smaller speakers can be used for center and rear. The AR 3a (or 11) do all the work you would want from a subwoofer so folks on this web site dont need the .1 in 5.1.

A week ago I picked up a Pioneer VSX-D908s with 5 separate discrete power amps inside with Mosfet transistors and rated at 100 wpc rms each. This unit is heavy and cost $150 on ebay. The sound from this even at modest volume levels was immediately noticeable. Very noticeable. Everything was cleaner and bass was particularly evident where it had been frankly lacking before. Movies sound a lot different now. This receiver also has an interesting feature that allows you to limit the bass output to your speakers by running a bass test tone (they say very low frequency and is maybe 40hz???) at gradually increasing volume and you cut it off when you start to hear distortion and then set the limit a few DB below that. I ran this test through the 3a's (actually AR 11's) and i stopped the test when it got to a bass level that I would not want to exceed just for the sale of earns and objects in the room. There was absolutely no distortion even with quite loud sustained bass. I was mpressed with the speakers (a daily occurrence) but also with the capability of the receiver.

If you are looking for a modest cost home theatre receiver the Pioneer VSX-D906s, 908s, and 909s look like good choices. They are mid to late 1990s vintage and all have the discrete mosfet 100wpc amplifier design and heavy transformers. The 906 is dolby digital only (about $120 on ebay), the 908 adds DTS, and the 909 allows a 5.1 chanel direct input. The latter 2 show up less frequently on ebay. A final note on these is that they, like many receivers, have an indication od 8-16 ohms impedance for speakers. And they have a setting for lower impedance which is safer for the amp but lowers headroom for the speakers. On the advice in earlier threads I have left these receivers in the 8-16 ohm setting as I am more interested in speaker headroom and less with melting down the receiver. And with judicious volume settings I ahve had no problems woth the receivers.

In other threads several have mentioned the Onkyo TX-8511 receiver which is stereo only (2 channel) with low impedance capability and 100wpc. These are heavy ans apparently well suited the to 3a type speakers. I have come close to buying one of these at about $120 but not quite. I have a couple of older Pioneer amps with 2-channel amps at 100 wpc that are heavy and do a good job. So if you are just going for stereo and a modern receiver with modern features these are possibilities.

Lest I get pounded by the purists on this site, I still have my LSTs with an adcom GFA55 in the basement for serious listening. I test drove an Adcom 5802 a couple years ago from a stereo store and heard no difference at all so easily made myself hapopt with keeping the 555. With this kind of power (325 wpc at 4 ohms) you really can make the house shake and my wife tells me she can hear the musuc more than loud enough upstairs when it is on in the basement. Increased volume, is free of distortion, is intoxication, as all on this site know.

In conclusion, my 2 cents are that the KLH 20 (I have one but never put AR speakers on it other than 4x's) will be ok at low volume levels. For modest volume one of the light weight 100wpc receivers may be ok. For moderately room filling sound the Onkyo TX8511 (or 8522) is good in stereo only and the Pioneer VSX-D906,8,or9 are good for hhome theatre. But if you really want to fill a room, go bigger power. Adcom is the leader in cost per power and sound good. As one of the regulars on this site always says (sorry I cannot remember who and do not want to plagerize) --it is all bbout the music--.

Steve G

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  • 2 weeks later...
Guest avs3259

I was gone for a few weeks and upon my return I was quite surprised to see the amount of attention this question drew. It is apparent from the comments that a Model Twenty, in any condition, is not up to driving a set of 3As.

I have a fairly early Model Twenty (1966-67) console with no speakers. The ARs are out. An obvious possibility is the KLH Model Twenty speakers that were meant for this system. These show up frequently on eBay. And while it makes more sense to keep the system all KLH another possibility worth considering is the Smaller Advent Loudspeakers. I believe these are a Kloss design so it would be in the family- sort of.

While waiting for a set of speakers to come along I have some electrical problems to deal with:

a) I hooked up a set of Model 24 speakers (8 ohm but that's all I had) and immediately noticed the system has a very muffled sound, and very little power; plugging in headphones automatically turned the speakers off but the sound through the headphones was just as muffled. I don't know if the impedance mismatch is the cause of ALL of this (part of it for sure). I ran the system for only 2 or 3 minutes this way and then turned it off. I really need to come up with a 4 ohm loading and plug the headphones back in.

:( with a CD player connected to AUX1 and playing, I switched the selector to AUX2 where nothing was plugged in. I could hear the player on AUX1 clearly as if the selector was still on AUX1.

Anyway, thanks to all for the replies.

-avs

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Guest matty g

Hi -

If you haven't found a set of Model Twenty speakers for your system yet, I have a near mint pair for sale cheap. If you want to come pick them up I'm in NJ, just e-mail me if you want them (I figure something like $50 for the pair). I've never shipped anything like that before, but it's probably not a big deal. I think you can just click on my name for the address.

Concerning the other issue - one of the inputs is a mono input, so check that you haven't plugged one of the cd player's jacks into the stereo in (aux 1) and one into the mono in (aux 2). Hope this helps.

Matt

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  • 9 months later...
Guest CHRISFL1

This posting may be too late to help, but I was working for a KLH dealer at the time the KLH Model Twenty system was made. The original speakers were essentially the KLH Model 17's in a 4 ohm version with RCA plugs vs. screw terminals. This was their top "compact" audio system at the time. I recall that we would occasionally sell one of these systems with the KLH Model 6 loudspeakers (more like the AR 2 series) and while the bass was better, they could not be driven very hard without the amplifier distorting. I believe that the amplifier was also equalized for the original speakers. So, my vote is that this would not be a good match for the AR 3s).

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