AR crossover L-Pads with resistors

[J8944]

I hope someone with more technical expertise than I have can help me in understanding the "correct" value of resistor to insert when using (2) 8 ohm L-pads in an AR-5 crossover. From what I read onIine I have inserted a 25 ohm 10 watt resistor (Dayton Audio Precision 10w 1%) across terminals "1" and "2" on each of the new L-pads. When I measure the resistance of the original AR pot I get 15.9 ohms across the whole range of settings. If I measure the L-pad with a 25 ohm resistor across terminals "1" and "2", I get a minimum of 0 ohms to a maximum of 25.0 ohms. But if I put a 16 ohm resistor in the same spot I get a minimum reading of 0 ohms and a maximum of 16.1 ohms. Doesn't the 16 ohm resistor come closer to the original value? Which is the better value to use and how will the two different values affect the sound from the midrange and tweeter? Will the 16 ohm resistor give a louder sound to the mid and tweeter compared to the 25 ohm resistor? And if I use no resistors on the L-pads how will that affect the sound?

[Aadams]

It has been a while since I looked at my Lpad wiring but I am pretty sure your resistors are connected incorrectly.  They should be attached to the posts labeled B and 2 as shown by your ink marks.

Look at this thread about halfway down the page.

 

[RoyC]

On 12/3/2023 at 5:33 PM, J8944 said:

I hope someone with more technical expertise than I have can help me in understanding...

Your controls are incorrectly wired, including the placement of the resistors. It appears you labeled the L-pad terminals 1,2,3 (from left to right in your photo). If you look at the numbers printed on the terminals, you will see they are actually 3,2,1. The L-pad's terminal numbering is different than the 1,B,2 of the original controls.

The resistors are also supposed to be connected between 2 (center terminal) and 1 (far right terminal) of the L-pad.

The L-pad without a parallel resistor will provide greater output than connecting a resistor (of any value). The 25 ohm resistor will provide greater output than a 16 ohm resistor, and will result in a close match to the behavior of the original controls. A parallel 16 ohm resistor in this application is not at all appropriate.

Roy

[J8944]

Thank you Roy and Aadams for your replies. Yes, I had the resistors wired to the incorrect L-pad terminals. I fixed that and also two other contact points in the sister speaker. Now everything works fine. Thanks again.

[Anthonyv62]

I used phenolic ring replacement tweeters from PE in my AR-4X restoration since used original tweeters were unavailable at the time. Everything is wired exactly like they were when they left the AR factory. The woofers are original and in excellent working order, but the original pots were replaced with L-pads and the caps were replaced with Dayton's. Overall, they sound more than impressive even with the phenolic replacements. Although I was only 4 or 5 years old when my father bought them back in 1966 or 67, I don't recall what they originally sounded. I do recall everyone who heard them commenting how - compared to their big combination turntable/tuner console stereos, which was more like furniture - the ARs were very balanced and extremely clear sounding.

My question is this: If I used a 25 ohm 10 watt resistor across the phenolic replacement tweeter terminals what would the audible changes be to the tweeters (when adjusting the knob from "decrease, normal, and increase on the L-pad) compared to not using resistors? The main reason I'm asking is because the phenolic tweeters can sometimes sound a little bright depending on the recording. If possible, I'd like to tame the highs a little more than what the L-pads with no resistor allows for. 

[Aadams]

12 hours ago, Anthonyv62 said:

I'd like to tame the highs a little more than what the L-pads with no resistor allows for. 

12 hours ago, Anthonyv62 said:

If I used a 25 ohm 10 watt resistor across the phenolic replacement tweeter terminals what would the audible changes be to the tweeters

The change will be the same as if the resistor were installed correctly on the L pad.  Not quite identical to a pot but you won't care.

[RoyC]

On 12/9/2023 at 1:30 AM, Anthonyv62 said:

I used phenolic ring replacement tweeters from PE in my AR-4X restoration...

My question is this: If I used a 25 ohm 10 watt resistor across the phenolic replacement tweeter terminals what would the audible changes be to the tweeters (when adjusting the knob from "decrease, normal, and increase on the L-pad) compared to not using resistors? The main reason I'm asking is because the phenolic tweeters can sometimes sound a little bright depending on the recording. If possible, I'd like to tame the highs a little more than what the L-pads with no resistor allows for. 

Anthony,

The various new replacement tweeters being sold by PE and others for the AR-4x have a different response than the original tweeter. Regardless of the level control used there is an upper midrange peak, which can be harsh sounding at higher volume levels and/or with certain recordings. Additionally, the original tweeter is actually stronger and smoother through the lower midrange frequencies, so a simple change in attenuators cannot correct for all the response differences. Unfortunately, original tweeters are getting very hard to find, and there is nothing closer than these drop-in replacements.

Given your general satisfaction with the new tweeter, the short answer to your question is that the 25 ohm resistor would tame the tweeter's response a bit. In this case, however, the usual value (25 ohm) resistor is not necessarily pertinent...though it should be the first one to try. If it does the job satisfactorily, your controls will then be ready for original tweeters, should you ever find a pair. Just be aware that any parallel resistance will raise the crossover point and reduce the new tweeter's contribution to the lower mid frequencies. You won't know if it provides the desired effect for you unless you try it.

There is no simple answer to this issue. There was a forum member (or two) working on a crossover change, but I don't recall the outcome.

Roy

[Anthonyv62]

Thanks. I appreciate you both for offering your excellent input. Everything you've added makes sense.

RoyC: I've come across a few original AR tweeters for the 4X, but not many. The ones I've found were almost always listed as "not working." Since I don't expect to find an original pair of original 4X tweeters (in decent working condition) any time soon, the replacements (as I've said) have worked out nicely.  It might be worth at least giving the added resistor a try since it's a simple addition and easy to undo. As I said, personally, the speakers sound impressive even with the PE replacement tweeters. I've heard only a few instances of the tweeter sounding a little bright - but not enough to be a distraction. 

I rebuilt these old ARs for my 20-year old son, not fully considering the fact that he has extremely sensitive hearing and can often detect "things" in sound reproduction (almost always treble sounds) that I can't fully detect. Before I "rebuilt" these ARs, he grew up listening to a pair of decent 1990s Bose speakers, which are obviously different sounding than classic ARs. I've told him to try listening to a few versions of whatever particular song that he's hearing too much brightness on and see what happens - which has made a difference for the most part. I've also explained experimenting with a resistor to the tweeter idea so he could decide for himself if it makes enough of a difference to him.  I'll wait and see what happens.

[RoyC]

That sounds like a good approach. In this case it is more about the most acceptable compromise.

Your situation is not uncommon. The harshness becomes more apparent as the volume is increased. It can be annoying, especially when compared to other vintage speakers (including Bose).

[Anthonyv62]

RoyC, Thanks for letting me know I was at least on the right track in my approach. Including a resistor is a simple, easily reversable "tweak" if I decide to experiment a little bit with the replacement tweeters.

My son has been listening to these speakers for hours on end every day since late November. He's pushed his ARs pretty hard playing a lot of different recordings and has warmed up to the vintage sound with each passing day. At first, he told me not to pack away his old Bose speakers just yet, and today he boxed them up himself. He's also asked about possibly finding some larger model ARs to restore. Needless to say, he's put the resistor experiment on hold for now.  

I noticed that the phenolic tweeters from Vintage AR are sold with a slight treatment added to them - which is interesting. I know you can treat cloth surrounds with a specific application (I've considered doing it to my original AR woofers) but what does this treatment do specifically for phenolic replacement tweeters? 

[RoyC]

Vintage_AR is selling the Parts Express/Dayton tweeter. At my suggestion he brushes some of my surround sealant on the cone to damp its response a bit. The effect is marginal, but seems to be somewhat helpful. AR actually treated the original 4x tweeter in a similar way.

Roy

[JKent]

Anthony,

Here’s something out of left field: Years ago Roy recommended putting Avid drivers and xo in the AR-4 cabinet. Worth a try if you can get the Avid innerds. Avid speakers sound great but their cabinets are fugly. 

 

[Anthonyv62]

JKent,

I'm actually pretty satisfied with the PE phenolic replacements - but then again I don't have original 4X tweeters to remind me of how the speakers originally sounded. I also don't feel like opening up the cabinets and touching the crossovers since the speakers sound excellent as they are. Removing the tweeter to experiment with a resistor is about as far as I'm willing to go - for now. I was just wondering how I might "tame" any tweeter brightness (even slightly) if it becomes a major distraction and keeps my son from really enjoying them.   

Funny you bring up Avid as I was unaware that there is an added section on this site specifically reserved for Avid speaker. I owned a pair of Avid's when I was younger, back around 1975. I think they were 100 Series with the round corner, grey-brown Advent looking grills set in a square utility cabinet, about the size of AR-4X or Dynaco 25. Not much to look at, but they could easily handle endless hours of listening to WNEW-FM and albums by Frampton, Clapton, Pink Floyd, Led Zeppelin (especially "Houses of the Holy") at peak levels connected to a Marantz receiver. They were purchased as discount demo models either at Korvettes or S.Kleins in Woodbridge NJ. I also remember how remarkably good they sounded - not necessarily AR, Dynaco, or Advent level "good," but still pretty impressive sounding. I never bothered to check the availability of old Avids or Avid drivers before. And in all honesty, until you just mentioned them today, I haven't thought about them in a very long time.    

[JKent]

Avid 100s. Those are the ones. 
E. J. Korvettes! Bought my AR-XA turntable there in about 1970. Think the store was in the Millburn area. All my other early gear came from Sound Reproduction in East Orange NJ. Greetings to another NJ guy. 

[Anthonyv62]

Jersey Greetings to you too JKent! 

I think there may have been Korvette's around the Millburn area. I think there was one on Rt 22 near Blue Star in Watchung. I remember the Korvette's in Woodbridge sold their own audio line. I think it was called "MAX" but I'm not sure.  Around 1972-75 a lot of kids in my school received stereos for the holidays... a lot of them came from Korvette's. I knew I was fortunate (actually "spoiled") being able to listen to my father's system, but the Korvette's stuff (considering the cost) was NOT necessarily bad for what is was.

In December 1966 I was almost five years young when my father took me with him to pick-up his new AR speakers from Sound Reproductions in Newark, a block behind Hahne's. Years later he said he originally decided on KLH speakers, but after visiting the AR room at Grand Central Station (according to what he told me, the structure that AR would eventually use for their demonstration room was originally called "Hi Fi House") he knew the 4X was what he wanted. A few days after he brought the ARs home I remember watching him hook them up to his receiver. The first music he played with the new ARs were albums he let me pick out...Frank Sinatra's "A Jolly Christmas" and "Music of Christmas" by Percy Faith.

[JKent]

Wish I had gotten to Grand Central. 
btw, the Korvettes speakers were XAM (you were close 😁).

[Anthonyv62]

Yes. XAM was the correct name. Not sure if XAM included other Korvette's stereo merchandise or if it was limited to just speakers...I do remember that the speaker cabinets and grills did resemble KLHs.  Supposedly the cabinets were fitted with Electro-Voice speakers (which was more than possible) but stories like that were common in the world of inexpensive more "affordable" audio.  

[frankmarsi]

That's funny Kent as I would make the monthly stop at E.J. Korvettes because living in Staten Island at the time, it was the only big department store we had out there. S.I. at the time only had about 130 thousand in population, today it's over 400 thousand and over crowded. Korvettes was certainly well stocked as they carried many of the popular names of the era. I'd go and always asked to hear the AR-3a's which were newly released. Sadly most of the speakers on display were grouped close together on shelves and the bigger speakers on the floor, even bookshelf models. 

I also made my first 'hi-fi' purchases there. In late 1967 purchased a Dynaco PAS-3x pre-amp and a Dynaco ST-35 power amp., both tube models in kit form. I couldn't afford them until I started to accumulate cash from my new job working on Wall St.    After a few weeks and into 1968 my pre and amp were finished and powering two AR-3a size sealed enclosures I purchased on "Radio-Row" on Cortland St. close to where the first World Trade Towers were being newly built. 

In 1968 I was juggling hi-fi, playing in a hot local rock band and enjoying women because now, I had a car to afford me to actually get around, just like the old Beach Boys song with the same name "I Get Around", flip-side 'Don't Worry Baby'. It was a 45RPM I bought in late 1964.*         By 1968, I was in a band that was into and the newer rock music that was becoming popular like Hendrix, and many others that were the music we went after and played as covers. 'Hard-Rock' was fast becoming the most current rock music at the time.

Those 'XAM'  speakers Korvettes offered in different sizes I couldn't warm up to as they sounded muted and dull. Did they have E.V. drivers inside, I can't say, just didn't sound good to me. Certainly not after having my mind and heart set on AR's.

I went back to Korvettes to buy my exciting at the time, the AR-xa for $69.00 to replace the Garrard 40B I first bought along with the Dyna components. The AR-xa sounded so much better than the entry level Garrard but, that's another story. Mounted my Shure M3D and later a Shure M55, then a Shure 91E. That was 56 years ago and yes I'm dating myself. There were common societal problems in the culture but, everything for an 18 year older was so much better in this country than today. In fact I felt it was GREAT to be alive!  Eleven months later I was in boot-camp and serving my country and everything in my life was put on hold.

P.S. * I still have that very same Beach Boys 45 RPM single disk. It's worn and the SQ sucks but, I'm happy to say I was there in those years, it was great and I would do it all over again. In factor  the younger folks who only discovered vintage hi-fi components of yesteryear with the last twenty or thirty years or so, all I can say it was better in the Classic Era of hi-fi while it was first hand and all brand new, you late-comers missed a lot. However, hope springs eternal and many of those vintage components were built and designed well and have survived so, you can still have some of that original pleasure boomers like me did. I'm glad there are folks that allow it to live on even though it's old.

P.S. The appreciator that I am, I can tell you that I still have all of the above mentioned equipment, the original guitar and bass that I played, the pre and amp, and dead Shure cartridges. The hip-hugger, bell-bottom jeans and Nehru shirt and love-beads and elephant hair bracelets are somewhere in a box., but most of the clothes were donated.

But wait, from 1964 I still have my "Beatle"-boots in good condition. And yes, if I found a minty pair of AR-5's at a good price I'd snatch them up. They were as far as I could go in cost back then as the AR-2ax just wasn't for me at the time but, this AR-5's are still attractive. When I bought the AR-3a's in 1971 it was a huge financial stretch for me and it took months to make back that money. Yet, they set the pace for me back then and all I did was to make my AR hi-fi system grow bigger and better.

FM

 

 

 

 

 

 

 

 

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[JKent]

Yeah Frank. My purchases were just a couple years later but nearly identical: ST-35, PAT-4 (both kits) AR-XA tt, KLH Eighteen tuner, AR-4x speakers. I still have the speakers, table (now with Sure V-15 Type V cart) and tuner but I sold the dynakits about 20 years ago. Got 10 times the original price for the ST-35. Nice little amp. 

[Norman Nicolai]

As a former Staten Island resident and current Jersey Guy, I need to add my 2 cents to this conversation…

I remember both the AR Listening Room in Grand Central and EJ Korvettes on Staten Island. 

I was a HS student back in the late 1960’s and early 1970’s. One of my first summer jobs was working as a messenger out of the Lower Level of Grand Central Terminal, near the Oyster Bar and the defunct Fanny Farmer candy store. (For very young readers, before fax machines, emails and scanning, documents had to be transported by hand from one place of business to another place of business. Interesting aside: I used to deliver to Philip Morris Co. on Park Avenue almost daily. Even though I was only 16 yrs old, the receptionist always asked if I smoked. I did, and she would offer me a free pack of Marlboro’s, which I eagerly took. Cigarettes were only .45 cents a pack back then!) I took the Staten Island Ferry from “the rock” as we affectionately called SI into Manhattan every day. There was no air conditioning in Grand Central Terminal at that time except in the AR Listening Room on the Mezzanine overlooking the main concourse of the terminal. I spent many of my 30 minute lunches escaping the summer heat in the coolness of the AR Listening Room. It was such a serene place and you could just relax and listen music. It was also my introduction to high fidelity audio. I was thrilled when my father brought home a KLH Model Twenty Music System purchased from Harvey Sound on 45th St. later that year. While not as good as a component system with AR speakers, it was a huge step up from my Webcor stereo. 

I also vividly remember EJ Korvettes on Richmond Ave of Staten Island, where the SI Mall now stands. At that time it was across the street from the garbage dump landfill, now closed, but one of the highest points on the eastern seaboard, originally built on marshland. Anyway, Korvettes had a record dept. right next to their audio equipment on the 2nd floor of store. I would frequently get off the No. 114 bus on my way home from HS to shop for vinyl LP’s there. Korvettes had incredibly low prices for records, ranging from $2.25 up to $5.25. The prices were color coded with stickers on the plastic wrap of the LP with the color pricing guide on the tall columns inside the store. They had a huge selection and terrific prices, so at the height of the “Rock Revolution”, and just before Woodstock, I was the proverbial “kid in a candy store”. I built up a huge collection of albums during that time period, largely from records purchased at Korvettes. Unfortunately, many of those same LP’s were lost in a basement flood years later. 

It’s great fun to reminisce…

 

 

[Anthonyv62]

The XAM's were obviously not in the same league compared to the classic brands that get mentioned on this forum, but they weren't much different than other inexpensive audio products in the 'late 60s and '70s. I heard a lot of those Korvette systems in a lot of home basements and bedrooms throughout the 70s. My impression was that most XAM speakers (at least the ones I heard) tended to sound mostly bright and thin.

I also remember those "cut rate" brands usually found in stores like Korvette's were very similar. They seemed like they were meant to be basic, entry-level, and affordable - nowhere close to the stuff I'd see at Stuarts Audio in Westfield. I learned that brands like XAM could serve a simple yet important purpose for customers who bought them. No, of course they weren't high-end, and nobody in their right mind should have expected them to perform at that level. But they could become a first step moving up to bigger and better audio. In that regard, regardless of where they were sold, who made them, or how much they cost, I'm sure they succeeded on many basic yet important levels. As my father often told me, "Regardless of the name is on your stereo, what's most important is enjoying the music."