Dyna ST70 driving AR3a's - enough?
Bill Yee
my all original Dynaco Stereo 70. I find that the sometimes bass heavy AR-3a
tends to offset the weakness of bass in the Dynaco Stereo 70. Thus they mate
well together. As for how loud you think is loud enough (that is a subjective
matter), that is something only you can judge. All I can vouch for is that the
AR-3a and the Dyna Stereo 70 match well. They are capable of providing rich
smooth extended and satisfying sound. And IMO the Dynaco Stereo 70 is very
capable of driving the AR-3a's. Also remember that the AR-3a's rated nominal
impedance of 4 ohms will need to be connected to the Dynaco Stereo 70's 4 ohm
tap. If you use the 8 ohm tap, the sound will be brighter in the midrange and
highs... but there will be an impedance mismatch running them that way. I
prefer the 4 ohm tap connection for an overall more laid back, smoother and
naturally pleasing sonic presentation.
I also like the idea that the low 35 watts per channel of the Dyna Stereo 70
will not easily overstress the 30 years old AR-3a drivers! I always worry about
that when I am playing them loud. I don't want to burnout or mechanically
overstress my Classic old AR-3a's. So play them at moderately loud levels.
Once they are gone they are gone forever!
John Rethorst wrote in message ...
>I know that in the 60's there were lots of Dyna ST70 amps driving
>enormously inefficient Acoustic Research AR3a speakers. Has anyone heard
>this combo? Can it produce a reasonable volume (for classical, with its
>wide dynamic range) ?
>
>---
>John Rethorst
>
>Please delete the x for email.
William Boyd
my ST70. Strawberry Fields was the first record I played and even tho they were on
the floor, it got my attention. I think the room size may have a lot to do with it
too.
Bill Boyd
jacks...@mindspring.com
jc...@xcornell.edu (John Rethorst) wrote:
> I know that in the 60's there were lots of Dyna ST70 amps driving
> enormously inefficient Acoustic Research AR3a speakers. Has anyone heard
> this combo? Can it produce a reasonable volume (for classical, with its
> wide dynamic range) ?
>
> ---
> John Rethorst
>
> Please delete the x for email.
John,
When AR had their music room in Grand Central Station in NYC they used a
STEREO-70 & PAS-3x to drive ALL their AR speakers until they came out with
their own solid-state electronics. They made a point of never playing them
loud in the room. I have 3As & have driven them in the past with the ST-70
& it is fine up to a civilized volume. If you're going to push them hard,
you'll definitely need something else. If you overdrive any amp it will
clip & that is sure death for the upper drivers. I've read every thread
thru # 9 here & there is some misinformation about 3As. Firstly, the
mid-range was NOT awful as someone claimed. Some may not like it, but the
fact is that few mid-range drivers before or since have ever been that
accurate. The tweeter for some may leave something to be desired, but with
a simple add-on described below you can turn this box into a gem! The
speaker should absolutely NOT be placed on the floor. It is no slouch in
the low end & certainly will be bottom heavy that way. I have found that
they have the best balance a couple of feet away from the walls. I have
mine mounted on old AR stands that are 11 inches off the floor. These
stands are 2 pieces of solid walnut that form an "X" base & used to cost
about $7.00 in AR's heyday. Read it & weep! Them days are gone forever!
If you want to really wake up the 3A & give it new life, get a pair of
Radio Shack's Linaeum tweeters ($30.00 each) & sit them on top. They
restore the high end that many find lacking in the 3A without getting too
bright and add some "air". They have no built in level control & in my
set-up I don't find the need for one. Radio Shack's part number is
40-1389. They call it the 3x4 dipole tweeter in the catalog. It's actually
a kind of ribbon tweeter.
I use them with a Hafler 220 and it's a very happy marriage. My listening
runs to classical and jazz & big band.
In the sixties, Micro Acoustics made a similar device with cone drivers
which had the same effect. It lookes like a small Janzen tweeter. Not
keeping the one I tried then was one of my great audio goofs!
One of the real pains with the older ARs are the level pots. As any
experienced AR devotee knows, they have a tendency of going silent or
intermittent due to wear or corrosion. AR later came out with a sturdier
pot (I have accumulated a boxfull to insure I can keep the thing alive)
but they also are somewhat finicky. From time to time, I find it necessary
to remove the woofer (carefully) & go inside & spray some tuner cleaner in
the pot while rotating the shaft.
Someone wrote: <Folks who bought Dynakits probably didn't buy AR3a's. If
I recall correctly they listed for about $600/pr in the early 70's.<
Not true, they were a very popular combination and AR & Dynaco had close
associations. The 3As lisred for $250.00 each and typically sold for about
$180.00 (NYC area) in real WALNUT. Eventually AR went the vinyl-clad route
on most of their line.
Bill Yee wrote: <I find that the sometimes bass heavy AR-3a tends to
offset the weakness of bass in the Dynaco Stereo 70.>
I'm not interested in a discussion on this, but the ST-70 is NOT weak in
the bass. Left alone & not modified by the self-appointed "gurus" out
there it was and is a superb amplifier within its power rating.
Bill Yee further rote: <I also like the idea that the low 35 watts per
channel of the Dyna Stereo 70 will not easily overstress the 30 years old
AR-3a drivers! I always worry about that when I am playing them loud. I
don't want to burnout or mechanically overstress my Classic old AR-3a's.>
See my comment above on clipping.
Room size of course will have a huge effect on power requirements. I
bought my firsat ARs (AR3s) in 1967. Until then I always believed them to
be terrible based upon hearing them in stores. They did not demo well and
the pots were generally always set too high or too low. A musician friend
had a small but excellent recording studio in his home. The first time I
went there I heard his AR2axs in his control room & was absolutely blown
away by their power & accuracy with a decent but modest amp. (don't recall
what) The control room however was quite small and I was standing right
next to the speakers. I was never able to recreate that effect in my
listening rooms unless I got right on top of them. I went out the next day
& bought the 3s & later the 3As & have not been able to be satisfied with
anything else I could afford or have heard since. As a musician and former
recording engineer it's the standard for me for accuracy and REAL bass
response. Sorry to go on so long, but with all the crap & hype that's out
there now, this is a bit of a passion with me.
Happy listening!
jack...@mindspring.com
William Boyd
think the midrange is very accurate. It is a little congested though IMO due
probably to the constricting beamwidth of the 12" driver (heavy cone too)
going up to around 600 hz. I've experimented too with some mid/top scenarios
to help them out a little. Right now I'm working on a top mounted Audax
5"aerogel and a Scanspeak silk tweeter with new xovers to the AR woofers down
at about 350 hz - preliminary results are pretty stunning. I like the
Linaeums too & may give that a try. One thing I know - the AR3a and AR303a
(versions I'm using now) produce the best, strongest, deepest and most
effortless bass of any speaker I ever heard anywhere close to their size, let
alone cost. I use two pair, have to run the woofers in series with a tube amp
(~10-12ohm load) or parallel with solid state (~2-3 ohm), and am just sold on
the bass - have been for twenty five years - I also use a fairly simple opamp
equalizer to produce flat response to 19 hz and the AR's take it without any
noticeable strain at all. I'm trying to get the kind of airy, sweet sound
with pinpoint imaging I get from my B&W DM7IIs, and with as much tube
amplification as possible. I'd be interested in email discussion with anyone
interested in continuing this thread outside the RAT so we won't intrude into
too much tubedom.
Bill Boyd
Bill Yee
jacks...@mindspring.com wrote in message ...
>... Firstly, the
>mid-range was NOT awful as someone claimed. Some may not like it, but the
>fact is that few mid-range drivers before or since have ever been that
>accurate.
level is adjusted
properly in relation to the tweeter and the woofer levels.
>... The tweeter for some may leave something to be desired, but with
>a simple add-on described below you can turn this box into a gem! The
>speaker should absolutely NOT be placed on the floor. It is no slouch in
>the low end & certainly will be bottom heavy that way.
I find that the tweeter of the AR-3a's needs to be turned all the way up on its
level control. Like this it
is just about right in the ball park and adequate. However some folks may just
prefer a little more sizzle
and complain that it does not have enough highs. I disagree, for my AR-3a's
sound just right like this.
Some folks claim that soldering the tweeter hot wire to the full on position of
the tweeters level control
gives you about 1 db more output from the tweeter. I chose not to modify my all
original set this way.
Some folks mistakenly remove the level control totally from the circuit or
replace it with a resistor. I
would recommend that you not do this! My analysis of this is that the wire
wound level control windings
have some inductance and sonic value to them that contributes towards the
AR-3a's traditional characteristic
sound. By removing the level control and replacing it with a resistor the
original AR sound is affected.
It is better to keep the level control in place and just solder the tweeters
wire to the full "on" position lug of the
pot. That way it is like the level control is turned all the way up and the
sonic virtues of the pot stay put.
>If you want to really wake up the 3A & give it new life, get a pair of
>Radio Shack's Linaeum tweeters ($30.00 each) & sit them on top. They
>restore the high end that many find lacking in the 3A without getting too
>bright and add some "air". They have no built in level control & in my
>set-up I don't find the need for one. Radio Shack's part number is
>40-1389. They call it the 3x4 dipole tweeter in the catalog. It's actually
>a kind of ribbon tweeter.
I am using the same Linaeum tweeters with an old pair of AR-2's. I think that
the tweeters are nice, but will need some
toning down. That can be down with simple addition of series resistors to the
tweeter. But I have not tried it with my
AR-3a's because as I stated above, my AR-3a's tweeters sound fine just the way
they are turned all the way up.
>Bill Yee wrote: <I find that the sometimes bass heavy AR-3a tends to
>offset the weakness of bass in the Dynaco Stereo 70.>
>I'm not interested in a discussion on this, but the ST-70 is NOT weak in
>the bass. Left alone & not modified by the self-appointed "gurus" out
>there it was and is a superb amplifier within its power rating.
I did not mean to say that the Dynaco Stereo 70 was anemic in the bass. Yes it
does have bass, but that is not its
strong suit. Compared to other amps tube or solid state, the Dynaco Stereo 70
does have less of a bass output though.
But it is way better sounding overall than alot of the other amps out there
moderna and new, solid state or tubes!
Also, I agree, that the original unmodified Dynaco Stereo 70 sounds better than
most of the modified so called
"improved" Dynaco Stereo 70's out there today. I have not heard all possible
mods of this amp of course, but of the
ones I have heard, I'll take the all original version without question! So all
you Dynaco owners listen up! Leave them
all original and don't butcher up a true classic! They are also IMO worth more
money all original and untouched by some
so called "guru's" hands.
>Bill Yee further rote: <I also like the idea that the low 35 watts per
>channel of the Dyna Stereo 70 will not easily overstress the 30 years old
>AR-3a drivers! I always worry about that when I am playing them loud. I
>don't want to burnout or mechanically overstress my Classic old AR-3a's.>
>See my comment above on clipping.
>
I was not talking about clipping of amps to fry tweeters. I am aware of the
fact that most folks fry tweeters using
lower power amps driven into clipping than larger power amps. I simply was
referring to playing the AR-3a's at
fairly loud and clean levels without clipping the amps. I have a 250 watt per
channel RMS Adcom solid state amp
that will easily pop or overstress my AR-3a's drivers playing loud and clean
without clipping. I know, because I
have come so very close to that dreaded moment...! When I play them loud with
lower tube amp wattage, my AR-3a's
won't get so mechanicallly stressed. The old and aging glues holding the cones
together etc. won't break loose and
tear, etc. Know what I mean? This will happen to old aged and dried up brittled
drivers. So be careful. By the way I
believe I am well enough along in this line of hobby/work to esily know or hear
when I am really overstressing my
amp or speakers. I never or rarely play my stuff at clipping levels these days.
I did when I was a young punk teenager
in my early days of Hi-Fi Stereo back in the 1960's and 1970's. No I don't clip
my stuff anymore. Just nice easy
comfortable levels of listening. Very and most enjoyable this stuff is. I love
it to heck.
Mr. James C. Mcshane
AR-3a. My source for this info is my uncle Chuck McShane who was head
of AR R&D in the late 60s/early 70s and the chief engineer for the 3a.
Chuck says the pot needs to go, so do what you want, but I would
bypass it.
Jim McShane
MLJ...@prodigy.com
Bill Yee
Mr. James C. Mcshane wrote in message
<79hl4j$275g$1...@newssvr04-int.news.prodigy.com>...
Yes, bypassing it is just fine and dandy. But I would leave the pot in place
and just solder the tweeter lead to the full on lug of the pot leaving the wire
wound pot resistance and inductance (and its sonic characteristics, however
subtle) intact.
The midrange unit needs to have an adjustable level control to tone it down a
bit, so do not bypass the midrange pot.
Hey you are lucky to have an Uncle McShane that used to work for AR R&D. I used
to dream about being able to work there when I was a youg teenager in the 1970
era. I hope he is still alive and well and maybe you can ask him where I can
get some AR-4x original or equivalent tweeter replacements? Or who I can
contact to have some made up for me?
Hope he can help. Thanks.
Calvin O. Steve Kysar III
It is my understanding that the 3a is sensibly an inefficient loudspeaker.
Frankly, I think the stereo 70 is too small an amp to fully enjoy the
base response. Even though the stereo 70 has separated windings for 4,
8-ohm loads, a minimum of 75+ rms/channel is realy needed to get that
woofer loaded up and fired. AM I WRONG?? Steve.
--
Ned Carlson
I don't think you're *necessarily* wrong, and there may be amps
better suited than ST70's, but when AR's were first introduced,
the
typical amp had a power rating of 25-35W, like an ST70.
So I believe an awful lot of AR's have been used with ST70's
over the years.
The 1962 Allied catalog states that an amp of at least 25W/ch
is required for AR-3's, and an ST70 would've qualified.
--
Ned Carlson Triode Electronics "where da tubes are!"
2225 W Roscoe Chicago, IL, 60618 USA
ph 773-871-7459 fax 773-871-7938
12:30 to 8 PM CT, (1830-0200 UTC) 12:30-5 Sat, Closed Wed & Sun
<A HREF="http://www.triodeel.com">http://www.triodeel.com</A>
Tube and Tube Amp info on the net...<A
HREF="http://www.triodeel.com/tlinks.htm"> The Big Tube Links
Page!</A>
Bob C
>I don't think you're *necessarily* wrong, and there may be amps
>better suited than ST70's, but when AR's were first introduced,
>the
>typical amp had a power rating of 25-35W, like an ST70.
>So I believe an awful lot of AR's have been used with ST70's
>over the years.
>The 1962 Allied catalog states that an amp of at least 25W/ch
>is required for AR-3's, and an ST70 would've qualified.
I have a good friend who owned AR-3 and ST-70s for years and they were fine
together. He even ran a triode wired ST-70 and was very happy.
BC
--
come visit http://www.communicationjute.com
"...an unbeelievably comprehensive web site containing vital quotes by Andre
Jute." Admiral Robert Edwin Peary, North Pole Audio Society Newsletter
Frank Johansen
While an ST70 will make them work, if you want to see snap, particularly in
the bass, get something higher powered.
These speakers are capable of great sound, but do need massive amounts of
current to bark. Of course, this must all be related to many other things,
such as room size/environment, type of music, and expected volume levels,
but way back when, I clearly remember them as being power-hungry.
FWIW, of course, and the usual disclaimers apply. :)
frank
Bob C wrote in message ...
tomt...@nr.infi.net
MLJ...@prodigy.com (Mr. James C. Mcshane) wrote:
> Bypass that tweeter pot without fear if you want more top end from your
> AR-3a. My source for this info is my uncle Chuck McShane who was head
> of AR R&D in the late 60s/early 70s and the chief engineer for the 3a.
>
> Chuck says the pot needs to go, so do what you want, but I would
> bypass it.
>
> Jim McShane
> MLJ...@prodigy.com
>
With all due respect, I would take issue with James C. McShane. Chuck
McShane was not head of Research and Development, at least during the time of
the AR-3a introduction in 1967. He might have been head engineer, but it was
Roy Allison who was Vice President of Engineering and Director of Research at
this time. I am not exactly sure the role Chuck played in the development of
the AR-3a, but I know that he had a lot to do with the design of the 1-1/2"
midrange dome and the 3/4" tweeter that was used in the 3a. The AR-3a, of
course, was a refinement of the original AR-3, designed completely by Edgar
Villchur (Kloss had nothing to do with any of the dome-tweeter AR speakers)
and introduced in early 1959.
Chuck McShane I think also had a lot to do with the AR-6 speaker and its
rather novel 1-1/2" tweeter using silicon grease as a means of improving
power-handling ability (silicon grease, incidentally, is a better heat sink
than ferrofluid, but it will not stay in the gap after repeated high-power
episodes). The AR-6 (and later AR-7) tweeter had very uniform response, both
on and off axis; the AR-6 woofer had the same bass resonance as the larger
AR-5, AR-2-series, etc. The 8-inch woofer was capable of very large axial
excursions for a driver at the time. But the main design work on the AR-3a
was that of Roy Allison; the same is true of the AR-LST.
As for bypassing the level control for the AR-3a tweeter, this mod is good
for about 1 dB. The best overall balance for the AR-3a -- in most listening
environments -- is to turn the midrange level control to the "dot," or mid
position, and turn the tweeter to maximum or close to maximum. This gives
the most pleasing balance and the lack of brightness can become an asset if
overall power response (total energy in the listening environment) is the
most important consideration. Stacking a tweeter or electrostatic panel on
top of the AR-3a might improve the on-axis brightness, but it will not
improve the power response in most cases.
--Tom Tyson
tomt...@nr.infi.net
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Mark Williams
> It is my understanding that the 3a is sensibly an inefficient loudspeaker.
> Frankly, I think the stereo 70 is too small an amp to fully enjoy the
> base response. Even though the stereo 70 has separated windings for 4,
> 8-ohm loads, a minimum of 75+ rms/channel is realy needed to get that
> woofer loaded up and fired. AM I WRONG?? Steve.
> --
FACTOIDS: In its day, the 35 watt per channel ST70 was considered a good
match to AR3a's. It was another era. 60 watts per channel was big time in
1965. The 60 watt Dyna MKIIIs were better, but barely. A doubling of power
is barely perceptible by the ear.
It really depends on what kind of music you listen to, in what room size, and
at what preferred volume level. I do know you will blow the mids and tweeters
if you push too much power at them (I've done it). A rational approach might
be to use a tube amp like the ST-70 for the tweeters, and a solid-state brute
for the woofers. Something like a Dyna ST400 for the lowend, and the ST70s
for the mid/hi would sound pretty good and be archaeologically compatible
(same audio era). :-) This has real merit, because the midrange and highs
are really the strong suit of the ST-70 .
If you have a big room, or like your music very loud, you may want more
efficient speakers, it's cheaper to do that than use a bigger amp. It's the
physics, sorry you can't beat it.
tomt...@nr.infi.net
In a previous posting (below), I corrected the comments made by Mr. James C.
McShane, nephew of Chuck McShane, regarding the genesis of the AR-3a
loudspeaker. This is to further refine those comments.
The AR-3a was introduced in 1967 as a refinement of Ed Villchur's AR-3
speaker introduced in early 1959. While the AR-3 is widely considered to be
the finest loudspeaker commercially available from the late 50s until the
late 60s, it still needed refinement; wider dispersion, increased
power-handling capability, and so forth.
Roy Allison came to AR in 1959 (about the time of the introduction of the
AR-3) as Plant Manager and subsequently Director of Research. One of his
first tasks was to work on enhancing the AR-3, and improvements were
implemented. Towards the middle 1960s Roy worked on the new small speaker,
the AR-4, and he consulted with a fellow named Charles McShane (at that time
an engineer at CTS in Paducah, Kentucky) on the drivers used on the AR-4.
Roy hired McShane shortly after the introduction of the AR-4 (introduced in
1964), and Chuck became involved in the design of the AR-3a. Roy and Ed
Villchur had been discussing and ultimately arrived at the design parameters
of the AR-3a, and Chuck McShane was hired to do the liason with vendors and
do the model-making of the AR-3a. Chuch also made many valuable suggestions
regarding the design, many of which Roy approved, but all final decisions
were made by Roy Allison, and he closely supervised the progress of the new
designs.
The AR-5, brought out in 1969, and the AR-6 and AR-7 were Roy Allison's
concepts entirely, but Chuck McShane played the same role as in the AR-3a
described above. The AR-LST was totally Roy's design, and by this time
(1972), Chuck McShane was out of the loop entirely, perhaps had left the
company by this time. Apparently, McShane had acquired a defunct OEM speaker
manufacturing facility in Southbridge, Massachusett, and it was clear that
there was a conflict of interest for him and he had to leave AR.
I hope this clears up any misinformation or confusion regarding the AR-3a.
--Tom Tyson
tomt...@nr.infi.net
tom_...@hp.com
_____________________________________________
In article <7b1rll$bm9$1...@nnrp1.dejanews.com>,
rl1...@ix.netcom.com
Mark Williams <ma...@cup.hp.com> wrote:
> Calvin O. Steve Kysar III wrote:
>
> > It is my understanding that the 3a is sensibly an inefficient loudspeaker.
> > Frankly, I think the stereo 70 is too small an amp to fully enjoy the
> > base response. Even though the stereo 70 has separated windings for 4,
> > 8-ohm loads, a minimum of 75+ rms/channel is realy needed to get that
> > woofer loaded up and fired. AM I WRONG?? Steve.
> > --
>
> FACTOIDS: In its day, the 35 watt per channel ST70 was considered a good
> match to AR3a's. It was another era. 60 watts per channel was big time in
> 1965. The 60 watt Dyna MKIIIs were better, but barely. A doubling of power
> is barely perceptible by the ear.
Actually, the effect is quite audible. By doubling the power available, you
also double the loudness. Double the power = 3db increase in sound preassure.
By doubling the power available, you also double the reserve available for
musical peaks and complex musical passages. Even before the onset of
clipping, constriction caused by low absolute power is audible. Haveing
resently experienced this phenomena when auditioning a SE triode amp, I can
attest to a flattening and hardening of the soundstage. The effect was not
subtle and I am certain that I did not hear any clipping.
>
> It really depends on what kind of music you listen to, in what room size, and
> at what preferred volume level. I do know you will blow the mids and tweeters
> if you push too much power at them (I've done it). A rational approach might
> be to use a tube amp like the ST-70 for the tweeters, and a solid-state brute
> for the woofers. Something like a Dyna ST400 for the lowend, and the ST70s
> for the mid/hi would sound pretty good and be archaeologically compatible
> (same audio era). :-) This has real merit, because the midrange and highs
> are really the strong suit of the ST-70 .
>
Very good suggestion as not only do you take advantage of the midrange and
treble quality of the ST-70; you also bypass any power restictions from the
same amp.
Just be carefull on matching. I would suggest an outboard line level sub
crossover. This way you can control level and phase for better integration.
(Remember, if you can hear the sub working, its probably too loud...).
> If you have a big room, or like your music very loud, you may want more
> efficient speakers, it's cheaper to do that than use a bigger amp. It's the
> physics, sorry you can't beat it.
I don't know about that. If you relieve your low power amp from provideing
deep bass, your potential sound level should increase. Also consider that the
AR3a was designed for mid to far field listening; ie flat responce in the
reverberant field. In order to accomplish the designed integration of driver
responces, you need a med-large room.
The AR2 series was better suited to closer or near field listening. The cone
midrange driver's dispersion characteristics were not suited to flat off axis
responce. Also the specified power requirement for the '2 was lower as well.
Again implying usage in small or modest spaces.
Hope this helps !
Ross Lipman
W.B.
Well, the AR speakers of the 60's were just plain inefficient. To make
matters worse, they could not handle much more then an ST70 puts out
with out the possibility of blowing a tweeter or mid. If you want to
enjoy concert level music, replace the AR's. I know that this is
probably not what you want ot hear, because, if you are like me, you
just plain love the sound of vintage AR speakers. But the bottom line is
that they strived for a sweet, accurate sound with tight, articulated
bass. They can get quite loud, but if you feel the need to constantly
run you ST70 close to clipping, then adding even more power to the input
terminals of your AR's will net you nothing more then blown drivers.
Oh, position of these speakers relative to room corners, walls and the
like is critical to good sound (this is the case with any speaker). If
they are not already, put them on stands that have the mids and tweeters
at ear level when you are in your listening position (be it standing,
sitting etc.) Anyway, I would not suggest pumping gobs of power into
these venerable old speakers unless you want the heartbreak of blowing
some very fine vintage drivers.
Bill B.
William Boyd
Jacksonville, FL, I met a guy (forget the name) who's father had started a company
there called Phase Technology. They claim in their advertising to hold the patent
for the soft dome tweeter (I think - don't hold me completely to this), and that
the development for this took place somehow during the development of the early AR
speakers. Anybody know about this?
Bill Boyd