Musings on the AR-2ax crossover

[Carlspeak]

Phenolic ring tweeters are quite common and still available in 4 and 8 ohm versions from Parts Express. However, I believe they are now made in China for the most part. My measurements have show they have a quirky 1200 hz bump that's a PIA to get rid of. I'll soon be doing battle with a pair of PRT's in a pair of 4x cabinets.

[Steve F]

As I've reported previously, no AR speaker ever used the "phenolic ring" driver as part of its original design. I think it is being offered these days as a later-day replacement to the original AR 2 1/2" cone tweeter that was in the 1x, 2x, and 4x.

I believe someone (Carl?) also reported that the PR tweeter was a suitable replacement for the 2ax 3 1/2" midrange. But be quite clear: the phenolic ring tweeter was not an original AR driver.

Steve F.

[Carlspeak]

I believe someone (Carl?) also reported that the PR tweeter was a suitable replacement for the 2ax 3 1/2" midrange. But be quite clear: the phenolic ring tweeter was not an original AR driver.

Steve F.

It was definitely a suitable replacement for the 2x midrange because my customer purchased a MR replacement kit from a Boston area authorized AR repair center. I believe at that time the PRT's were made in the U.S.

[Mach3]

Little bit of research shows that the tone controls on a Marantz 2250B Receiver does the following;

Tone Controls

Bass: ±12 dB (50 Hz)

Mid: ±6 dB (700 Hz)

Treble: ±12 dB (15 kHz)

I think the frequencies listed are the "centers" of the band pass for each tone control. With the AR2-ax having crossover points of 1400 and 5000 Hz I would think that the "mid" tone control works within the mid band - but the "treble" tone control probably has little effect - though when I boost it I can hear more "air" and brighnness.

Since these are 6 dB slopes (on all the various high/low passes in the crossover) this means that the mid-range is actually playing pretty loud from 700 to whatever its upper limit (mechanical and electrical limit of the driver) - it is afterall high passed only. The tweet is playing pretty loud at 2.5 KHz as well - with the woofer trying to get some output all the way to 2800 Hz (octave up only 6 dB down or at "quarter power"). So the AR2-ax has most of its drivers playing simultaneously in the mid-range band.

Despite the apparent confusion the sound of the darn thing is pretty good. Though I leave all the tone controls at mid-value.

Thanks for the tip on the max value of the resistor - there was something about the claim that the pots at max were at 0 ohms that just didn't sound right to me. So I am glad I left them in (have to take what you read on the various boards with a grain of salt).

[Gerry S]

Little bit of research shows that the tone controls on a Marantz 2250B Receiver does the following;

Tone Controls

Bass: ±12 dB (50 Hz)

Mid: ±6 dB (700 Hz)

Treble: ±12 dB (15 kHz)

I think the frequencies listed are the "centers" of the band pass for each tone control. With the AR2-ax having crossover points of 1400 and 5000 Hz I would think that the "mid" tone control works within the mid band - but the "treble" tone control probably has little effect - though when I boost it I can hear more "air" and brighnness.

Since these are 6 dB slopes (on all the various high/low passes in the crossover) this means that the mid-range is actually playing pretty loud from 700 to whatever its upper limit (mechanical and electrical limit of the driver) - it is afterall high passed only. The tweet is playing pretty loud at 2.5 KHz as well - with the woofer trying to get some output all the way to 2800 Hz (octave up only 6 dB down or at "quarter power"). So the AR2-ax has most of its drivers playing simultaneously in the mid-range band.

Despite the apparent confusion the sound of the darn thing is pretty good. Though I leave all the tone controls at mid-value.

Thanks for the tip on the max value of the resistor - there was something about the claim that the pots at max were at 0 ohms that just didn't sound right to me. So I am glad I left them in (have to take what you read on the various boards with a grain of salt).

I did own a Marantz 2270; a "poor man's McIntosh". What attracted me to this unit was the "three way tone controls"; kinda "unique" among recievers of that era (maybe even today). I THINK I bought it primarily to drive AR3a's. My listening room( bedroom) was tiny, so it's 70watt/channel into 4 OR 8 ohms was "adequate". Can't remember whether it's a "tube amp" as claimed by some (I remember it as a "solid state" amp). I probably sold it for "higher power", and THAT'S when I really got into "high end".

"High end" for me at that time was going into "seperates". Bought Dynaco PAT-5 & a Dynaco 400 power amp in kit form. Somewhere along the way, I also got a Soundcraftsman (2020?) 10 band "graphic equalizer" (10 one-otave frequencies / channel). Over time, I learned that one CANNOT "EQ" out a resonance (tone arm, room, or speaker). I also learned the more "bands" I adjusted, an "improvement" for some situations caused "degradtions" in others.

Why do I consider this post "relevant" to the "quality" of "vintage" products discussed here? I believe "speaker coloration" can be significant if no attention is given to either cabinet or driver resonances. Apparently, AR DID pay attention to this, even though there were no "specifications" to "quantify" this for the consumer.

[genek]

I did own a Marantz 2270; a "poor man's McIntosh". What attracted me to this unit was the "three way tone controls"; kinda "unique" among recievers of that era (maybe even today). I THINK I bought it primarily to drive AR3a's. My listening room( bedroom) was tiny, so it's 70watt/channel into 4 OR 8 ohms was "adequate". Can't remember whether it's a "tube amp" as claimed by some (I remember it as a "solid state" amp). I probably sold it for "higher power", and THAT'S when I really got into "high end".

Classic vintage era Marantz receivers were solid state, but with a tonal balance that leaned toward the sound of Marantz's classic tube gear. There was some kind of problem with the 2270 that caused its power amps to only make it to around 55wpc into 4 ohm loads before going into clipping; this was corrected in its successor the 2275.

[JKent]

Classic vintage era Marantz receivers were solid state, but with a tonal balance that leaned toward the sound of Marantz's classic tube gear. There was some kind of problem with the 2270 that caused its power amps to only make it to around 55wpc into 4 ohm loads before going into clipping; this was corrected in its successor the 2275.

I had a 4270 for a while--the 4-channel version of the 2270. Never seriously considered keeping it because my vintage system uses a MAC4100. But the 4270 was IMHO one of the coolest looking receivers around. And heavy! Over 40 pounds without the wood cabinet (which is a must-have). It was only rated 25wpc x 2 or 70wpc x 4 but those were "big" watts! It featured "Marantz's exclusive Vari-matrix circuit which simulates 4-channel sound from normal 2-channel stereo programs" but I think that was essentially the same as a dynaco Quadaptor.

What was the topic again?

Kent

[Gerry S]

I had a 4270 for a while--the 4-channel version of the 2270. Never seriously considered keeping it because my vintage system uses a MAC4100. But the 4270 was IMHO one of the coolest looking receivers around. And heavy! Over 40 pounds without the wood cabinet (which is a must-have). It was only rated 25wpc x 2 or 70wpc x 4 but those were "big" watts! It featured "Marantz's exclusive Vari-matrix circuit which simulates 4-channel sound from normal 2-channel stereo programs" but I think that was essentially the same as a dynaco Quadaptor.

What was the topic again?

Kent

Yeah, Kent.Those Marantz recievers certainly LOOKED way cool; had that MAC "look " but at a fraction of the price. That's why I referred to mine as a "poor man's MAC". It would have served me fine if my speakers were anything OTHER than AR3a's (my "best" speaker at the time). When playing "rock stuff" even in a small room, I was dissapointed when I "pushed them".

Oh yeah...staying on topic! Think it was AR2ax crossovers. Depending on Brand and Model, crossovers in general can complicate the amplifier/speaker interface enomously. I remember KEF (104's ?) "conjugate loading" approach to make their speakers look like a "resistor". Some crossovers are poorly designed (ringing, very low impedance, very "reactive" phase angles, etc. KEF'S crossover circuitry alone exceeds total "cost of goods" of entire competing systems!

[Gerry S]

Jeez Louise where to start?

I guess first and foremost is the fact that transient response is critical to a well designed bass system - drums do "snap" and have a rapid decay rate - with a ported design which is sending a wave front 180 degrees out-of-phase with the real signal (after all it is the back wave that is going out that hole) there are real problems with bass transient response.

As for all those SOTA products? Unfortunately I don't own any of them - cannot afford them. But I have heard ALL of them in various places (shows, dealers, friends). The Carver bass box (~ 1 cubic foot) goes for around $2.5k per - still too much for me. But the point is that he is getting deep bass from a small box (with a huge Class D amp wrestling that sealed box cone into place). BTW: Carver is able to achieve this with vanishingly low levels of distortion.

I have never heard a Hsu system - but I HAVE heard very good things about them - reputedly one of the best designs around. I notice from his web site that he offers a system that can function either as a ported box or a sealed box - interesting. He seems to get good response both ways - and his prices are pretty nice.

As for the AR-9 - it is pretty much done around 30 Hz - the literature reports 28Hz but I don't think I can get that low - nevertheless as you point out it is enough for my taste (and most importantly I can afford it). If you want a real test for bass response try track 1 of "The Dark Knight" sound track. Some real low stuff there. The 9 will play all of this track but at much reduced volumes.

I too owned a set of 10pi speakers (in 1979) - a wonderful speaker that I thought was a great improvement over the AR-3a. Wish I still had them.

I will close by noting that I never move either the furniture or my speakers - I guess I am no audiophile - fine by me. I just love music and the gear is only something that allows me to access it.

best to you,

Then you are one very lucky "audiophile". I've found speaker and listener location with respect to room dimensions and boundarys play a HUGE role in sound "quality". That you can enjoy yours just by plopping them down makes me very envious...LOL .

[Gerry S]

Then you are one very lucky "audiophile". I've found speaker and listener location with respect to room dimensions and boundarys play a HUGE role in sound "quality". That you can enjoy yours just by plopping them down makes me very envious...LOL .

"I have never heard a Hsu system - but I HAVE heard very good things about them - reputedly one of the best designs around. I notice from his web site that he offers a system that can function either as a ported box or a sealed box - interesting. He seems to get good response both ways - and his prices are pretty nice".

Dr Hsu has just hooked up his "mid-level" VTF Mark 4 along with a Pioneer VSX-821-K multi-channel reciever into my system. Both items sat there boxed for several months because I was too lazy to hook it up. They are used with my BA HD9's (my "submission" in the BAS "shoot-out" posted elsewhere).

I don't know whether the configuration is "sealed" or "ported" or what the "specs" are (and don't care). I DO know the following: it contains a 12" driver driven with it's built in BASH amp. The Pioneer has a built-in electronic x-o set to 80 hz (the built in x-o in the Hsu sub is "bypassed").

Playing just music CD's in stereo only, I'm truly AWED by what it can do. Truly viceral with just about everything I've played on it so far!

Think I will post "Hsu Subs" as a new topic !