Quadapter Back, Yay!

[Mallette]

Yep, I know the diehard dual-channel mono "everything MUST come from the front, including applause" bunch turn up your noses, but I was immediately rewarded after a couple of weeks of front-only when I hooked up my ancient Hafler magic yesterday. I still hold that it is "pure" in that the amp is two channel and only that which emanated from the rear goes to the rear. Actually, the way it shines best is with two mike recordings. The main thing I immediately noticed on "Polovetsian Dances" was NOTHING from the rear. Studio recording...a good studio, but a studio. What WAS noticeable that the front image reached out to me with more depth. The K'horns just sounded bigger and more transparent.

On Sgt Peppers, shared with my audiophile understudy son, things got a bit more complex and fascinating. Of course, since it's a complete studio fabrication and inherently non-reproducible on a stage, it isn't subject to a "correct" image. All that mixing and such creates complex phase relationships. Nonetheless, it never got muddled in any way. Occasional discrete bits from the rear and sides, but mostly front.

Firesign, that incredibly complex mix, was a whole 'nother story with stuff suddenly popping in (like Deputy Dan, the holygram) right behind my right or left ear. Downright disconcerting and really good fun...actually MUCH more natural sounding than Dolby or any electronic processor.

My last music room wound up a complicated mess as the family gravitated there for TV and I added an HT reciever and rather complex speaker and amp switching to use my ST-70. Most of the time, I would up listening to the HT reciever. I decided this time it wasn't going to happen and I am glad.

Any visitors who insist on "good ol' fashioned stereo" from the front only, simply flick of the switch on the QD-1 and it's back to dual channel mono and the sound collapses forward.

Paid 5 bucks for that thing about 1977 and it remains the biggest bargain I ever got. I've seen them going for 75 or so lately on Ebay. Must be some others who remembered and returned.

Dave

[Mallette]

Can't help but wonder. Is there ANYONE on this forum who has heard a QD-1?

Dave

[Mallette]

I do. I saw one for sale on Ebay yesterday for $29. I was vaguely tempted to buy it, but I have no possible way to have rear speakers. There's not much inside - - a few resistors.

Good price. And, yes, nothing much there. Hafler just placed out of phase speakers in the rear when he figured this out. I remember seeing articles in the audio press about just doing that and nothing more. However, you were then at the mercy of the match of front/rear speakers and the odds of it being "just right" were pretty small. The QD-1 just added the nice ability to null balance the rear by setting the preamp to "mono" and then turning the balance control for minimum sound, which is, of course, the phase cancellation. Also, a volume control for the rear and a switch to turn off the rears. In my case, I have a couple of little Monte Carlos in the rear against the mighty K'horns. Seamless and all that's needed.

That's why I say it is not "processing" in any sense we normally use that word. Pure 2 channel amp output. While I know you understand what I am saying, I don't think many do.

Listened Moody Blues "Seventh Sojourn" after work. Lord, it had been years...way too long. What got me was that, even though it was a complex mix, there was not a lot of out of phase info...it went throught the QD-1 like a 2 mike stereo. However, that is really the best. All you get is a depth of sound field, sort of like near field listening but from further back and even more immersive. When it is pure like that, you often have to turn off the rear channels to really notice what is going on.

Hafler was quite a genious, and this is my favorite legacy of his work,

Dave

[djk]

http://www.the-planet.org/dynaco/Misc/Quadaptor.pdf

[Mallette]

Yep, djk...I suspeck Mark probably had the parts laying around and could put this together in about 30 minutes...

Dave

[Mallette]

Mark, I think the "quad" debacle and the awful mixes on the majority of DVD-A and SACD offerings did for the idea of 3D soundfields what the Hindenburg fire did for the rigid airship. Even though the concept is obviously far superior, the "Oh, the humanity" reaction steps in and the mind closes.

I'd probably be the same way except that I never bought any of the original "quad" stuff and got my QD-1 way back and have almost always had it in my system. Tried a few highly touted and well reviewed surround discs of the current attempts, and found them bad to awful. No idea what's wrong with these engineers. It's something I want to do some more experiments on once I can retire.

One really needs very minimal speakers in the rear for DynaQuad, but they need to be as good a quality as the mains. If I actually hear them, I get up and turn the rear volume down slightly. Until somebody really masters 360 degree recording and playback, all I want is that extended depth and sense of space that this little jewel of genious provides. Nothing that isn't in those grooves already.

Dave

[whatever55]

DYNACO 4-DIMENSIONAL SOUND SYSTEM

The Dynaco 4-dimensional reproducing system fully utilizes the capacity of conventional 2-channel re­cording, transmitting and playback systems to pro­vide front-to-back, as well as left-to-right source localization. This technique is based on the principle of incorporating additional program channels of re­lated, but discreet information by means of sum and difference matrixing during the recording, and recov­ery of these signals by proper connection of a front speaker to reproduce the sum information, and a back speaker. to reproduce the difference information.

At a time when numerous proposals for non-compatible recording and broadcasting concepts have been submitted by the manufacturers of "hard­ware", the Dynaco approach is unique in that it is fully compatible with present systems, is amazingly simple and inexpensive, does not obsolete existing equipment, and does not require any additional elec­tronic equipment whatsoever, It requires only the addition of loudspeakers to your present two channel stereo music system. A striking advantage of this system^. is its ability to retrieve hitherto masked ambi­ence,. or "hall sound", and directional information from many present stereo recordings. This is exclu­sive with the Dynaco system demonstrating it's musi­cal and technical compatibility, and truly providing "something for nothing". These ambience effects, normally masked by the direct sounds in a conven­tional two speaker system, are revealed in the rear speaker because they are composed of randomly phased components. They will be most evident. in recordings which were made "live" with an audience, and where an additional distant microphone was used for ambience pickup. The compatibility of this technique is further emphasized when it is ^.appre-dated that even later transition to a fully independ­ent 4-Channel system, if desired, al. such time as standardization has been achieved, would not obso­lete anything purchased for the Dynaco system. Also, because the human brain locates in-phase material at the front, and out-of-phase information at the back of the head, a surprising degree of front-back directionality will be apparent when headphones are connected normally, and 4-dimensional material re­corded in consonance with the Dynaco system is reproduced in the normal stereo mode.

A four corner speaker placement is popular with those more interested in directional sonic effects than in accurate music reproduction, Such an arrangement seems inconsistent with accepted musi­cal compositions _.and programming, performed on a stage before you. I ho Dynaco four speaker arrange­ment achieves maximum playback realism, and.morc precise stereo imaging of soloists, with proper dis­tribution of available energy. An exclusive virtue is the ability to simplify this system without loss of significant musical content by eliminating the front speaker, if desired for reasons of simplicity, room planning dissimilar speakers, lack of the blend cir. cuit, or inability to connect amplifier grounds to­gether. The center front location is then synthesized

by common information in the left and right speakers. A variation of this system is adaptable to four corner speaker locations if desired, too, with some loss of directional effect. It is .available on request.

Any matrixing system (and it is generally con­ceded that some matrixing version is essential for compatibility with present recording and broadcast­ing facilities); requires precise phase control through­out the circuit, which in the Dynaco system includes the speakers. Thus best results are obtained when all speakers have identical efficiency, impedance and sonic characteristics, since individual level con­trols are not feasible. In any case the front speakers should have identical efficiency and impedance curves to maintain separation. The back speaker may be split into two units^-, parallel or series connected, or back-to-back, if necessary.

Because the Dynaco speakers were from the out­set designed with great concern for a smooth impe­dance curve within very narrow limits, they are par­ticularly suitable for such a system, The A-25 and A-50 have virtually identical characteristics; quite unique even among models from the same manu­facturer, Thtis an A-50 can be used at the center front where more of the energy is reproduced, for instance, with A-25s in the other locations. So sig­nificant is the added realism from many recordings that a matched system of four high quality moderate cost speakers, such as the A-25, can yield greater fidelity than a pair of far more costly systems.

The most natural aural effects result when the back speaker is placed above the listener. More dra­matic directional effects are noticed when _.this speaker is closer to the listener, but ambience is enhanced by a more distant location. You should realize that any 4-dimensional system necessarily restricts the listening. area more than a 2-channel system, and offsetting the balance control will re­duce separation, so proper placement of the listener is important. Where possible, the front speaker should be slightly more distant than the left and right speakers. The added benefits of 4-dimensional effects will often be most noticed in small rooms, where space restrictions were previously a signifi­cant handicap.

The diagrams show the speaker connections for this system. The center front speaker is connected in series with the ground returns from the left and right speakers, and requires that the amplifier have 6 db of blending to maintain maximum separation at the speakers.' The back speaker is connected from the "hot" terminal of the. left amplifier to the "hot" terminal of the right amplifier. No connection is made from the back speaker to a ground terminal, Since the speaker impedance isolates the hot sides of the amplifier outputs, no amplifier damage will result from this connection. The common, or ground terminals of the amplifier outputs should be con­nected together.²

With many room layouts, it may be advisable to reduce the level 01 the back speaker with a series

dwara INC

3060 JEFFERSON STREET, PHILADELPHIA, PA. 19121

IN EUROPE WRITE; DYNACO A/S HUMWM, STRUER, DENMARK

10 MC1.1170 Printed in U.S.A.

put, The tone controls need not be flat, but should be identical in eacti channel. You can reposition the knobs on their shafts to indicate the center null position. Reconnect the center ground. Switch the preamplifier mode to the 6 db blend position. 3 The system is now balanced for 4-dimensional playback. The records listed below exhibit different char­acteristics, all of which add to the realism which has long been sought in recordings, but has here­tofore been lacking in playback. To observe this improvement, first play part of the selection with the back speaker switched out, and then add the back speaker while you remain in the same listening posi­tion. The back speaker switch is advisable when listening to noisy program sources too, since the noise may be more evident from this speaker. Note when the audience participates that the performers

reSistor. A simple device which win dceoininociatu a wide range of speaker efficiencies iiind proximate locations is a 10 watt, 20 ohm slide-type variable resistor. The back speaker should face the listener, and its level should be set so that it is not obtrusive.

To balance the four speaker system, use the fol-

• lowing procedure to null the back speaker: discon fleet the ground return from the ^.front, so the front speaker will be dead and the left and right speakers will be in a series connection which will be in parallel with the back speaker. Use the MONO mode on the preamplifier (A only or B only on the PAT-4; Mono on the SCA-80; A-FB on the PAS-3X). Play a record with the volume control at its most-used set­ting. Adjust the balance. control for minimum output through all speakers. Then adjust the tone controls -preferably to the flat settings-for minimum out-

A&M Records SP-4199 Lee Michaels Side 2 "Heighty Hi" stay in front, and the audience is in the back.

the beginning. Note how the sound of the chorus

Angel SB-3739 Vaughan Williams "A Sea Symphony" Side 1 at Seems to fill the entire room when they sing; "Behold, the sea .

"Spinning Wheel" Note how the instruments surround you, but the

Columbia CS-9720 Blood, Sweat and Tears Side 2 voices remain in front of you.

"K(.3ntakte" Especially note the directional effects toward

Deutsche Grammophon SPLM-138811 Electronic Music Side 1 the end of this side.

Pump and Circumstance", and Side 2 "Rule Brittania"

Philips SFM-23033 The Last Night of the Proms Side 1 " Note how the audience joins in around you.

"Amparito Roca" Note the applause at the end of the selection.

RCA Victor LSC-2827 An Evening at the Pops Side I

• 1. The 6 db Of blending is equal in amplitude and opposite In polarity to the crosstalk which is intrOckited by the center (front) speaker connection, and thus cancels out the cross­talk and insures full separation at the speakers.
• 2. Some amplifier designs may exist which do not permit Cornrrion ground connections between the two channels. If the amplifier manufacturer puts no restrictions on ground connections, which is true of the majority of available ampli­fiers, no problems will arise.
• 3. This blend resistor Wynaco patent lt 3,417,203] is incor^, porated in all Dynaco PAT-4 preamplifiers, all SCA.80 ampli^, tiers, and in all PAS.2X and PAS-3X preamplifiers made since 1965. For 4-dimensional listening, the PAT-4 is

switched to "A" and.-"B"; the SCA-80 is switched to the Blend position; and the PAS series prearnps are turned to the narrowest rectangle on the Blend switch.

Technical consultation with the manufacturer of the amplifier or preamplifier will be necessary to determine the correct value and location of such a network for installation in other amplifier systems,

In Dynaco PAS series preamplifiers supplied before 1966, the present resistors on the Blend Switch must be changed unless the unit has already been modified with the TC-3X kit. The 560 K ohms resistor between lugs #2 and #3 must be replaced with 68 K ohms, and the 270 K ohms resistor between lugs 4_.3 and _#4 must be changed to 33 K ohms. Use 10%, one-half watt resistors.

Use this hookup with the Dynaco SCA-35 and other amplifiers which lack the "blend" facility.

This arrangement requires the "blend" capability for maximum separation.

BACK

FRONT

LEFT RIGHT

tam. com.

RIGHT

LEFT, RIGHT

COM. GUM. HOT

LEFT

Optional Resistor

A NOTE OF CAUTION; Because the back speaker is in essence connected in parallel with left or right speakers when common information is present, some care should be exercised, particularly when the simpler 3^,.speaker hookup is used, when employ­ing speakers whose impedance drops to very low values. Some solid state amplifiers may not safely be tiriven^.to high power levels when speaker loads drop below 4 ohms. This is not a problem with Dynaco amplifiers and/or loudspeakers.

[Mallette]

W55, where did you come up with that info?

Dave

[Taz]

I don't have any idea how it compares, but I do enjoy my old Marantz 4270 Quadradial........................Taz

[whatever55]

W55, where did you come up with that info?

Dave

From Dynaco I have it in a PDF which shows the wiring diagram better. I could not post it properly. If you want it send me your email and I will forward it.

[Mallette]

I don't have any idea how it compares, but I do enjoy my old Marantz 4270 Quadradial........................Taz

Well, if you enjoy it that's all that matters. Whether it's comparable or not depends on whether any processing or steering is involved. That's where surround went south. May post my thoughts on that later.

Dave

[DizRotus]

W55-

I sent you an email. Please let me know if you don't get it.

Have you tried attaching the PDF to a post? It's the same as attaching a photo, except it won't appear in the post. It must be clicked upon to be viewed or downloaded. See the attached pdf of a Quadaptor manual.

Thanks,

[DizRotus]

Dave-

The pdf W55 referred to is attached. He was kind enough to promptly reply to an email with the pdf attached.

Thanks to your post, I'm trying to get a Dynaco Quadaptor. If anyone here has one to spare, please send an email.

[Mallette]

Thanks, Neil. He was kind enough to send me one as well and it's good to have it up for others. I am glad to find there are at least a few that have heard this in action. I certainly understand the suspicion in which anything with more that two speakers is held today given the abysmal way the industry handled and continues to handle multi-channel music. But Hafler's concept is organic and every bit as pure as 2 channel itself. If a modern engineer or developer would really start with this as a model there would be at least a modest market of real music lovers who want greater fidelity than that possible with stereo but do not want gimmicks and electronic processing, steering, and manipulation of signals. I can't put a finger on it, but even when this works well I feel there is something in the real music lover/audiophile makeup that rejects anything not created in their brains.

In my humble opinion, DynaQuad remains the standard for producing reasonably accurate sound fields that don't sound synthesized in any way.

Dave

[DizRotus]

Dave-

I look forward to getting and auditioning a Quadaptor. You can bet I'll share my impressions.

The QD-1 is one of the few Dynaco products I've never built or owned. Sadly, most (tube and solid state) are long gone, but I still have an SCA-35 and an FM-5. I miss Dynaco. Can you believe it was owned by Tyco during it's dying days?

Best,

[WMcD]

It is interesting to read about the need for very closely match speakers. Maybe that was the problem with my experiments.

I tried a QD-2 just using the center channel. It didn't seem to work, so I put the unit in storage -- and eventually tinkered with it on a different project. (Do you need a three-gang pot?)

In another experiment. I set up a Dynaco-like circuit with EV mid horn as surrounds in a garage about seven feet above the floor and used the Telarc Symphonic Star Trek which is advertised as having surround information.

There was only one instance of remarkable effects. It was on the Tribbles track. If I stood under one surround, they were located on the floor and were individually locatable.

BTW, another Telarc has Robin Hood shooting arrows from back to front but the text with the CD says that phase and level must be precisely set to make it work.

I concluded that I'd have to wait for a better room, better processor, and better speakers.

For me, there is a lot of other stuff to work on before I work on surround. It is not that I think everything has to come from the front. Just that good surround takes some investments.

Let add that the most impressive surround I heard was in a theater in Hawaii showing Star Wars (I). In an early scene the Rebels are in a small ship when the Imperial ship clamps onto it. The impressive clank came from all around.

Keep up the good work. I like hearing about your work.

WMcD

[Mallette]

Gil, you're a tough guy to disagree with, but I do. I bought a QD-2 and you may be right. It's been a long time, but I recall it didn't work as well as my QD-1. Perhaps you could look at the circuit and see if it is different.

The QD-1 doesn't require identical speakers, just ones that tonally match. I am using Frazier Monte Carlos for rears with Klipschorns. No center, as the QD-1 doesn't support one. It is working beautifully. On most material I am not looking for nor is "discrete" sound from the rear even disirable. As I've said, if I hear them on a symphony or big band recording, I turn them down a bit. All I want is the rear reflections producing the depth that simply isn't there if that information is forced to the front.

The Hafler system isn't what I want for real 3D sound. I want discrete. I've written this up over the past week or so and its on my blog here. However, it's great for older sources. It may be my imagination as I can't really think of a technical reason why this would be so, but it seems to work better with analog than with digital sources.

Dave

[DizRotus]

Dave and Mark-

I plan to use the 4 identical single driver BR speakers (see "Single Driver Experimets" at http://forums.klipsch.com/forums/t/56563.aspx and a chip amp (see "Chip Amps" at http://forums.klipsch.com/forums/t/174973.aspx) to experiment with a QD-1 I hope to acquire soon.

Dave-

When I first saw this thread, I was excited, thinking the QD-1 was being sold new again. Alas, it was not to be, but I'm eager to try this just the same.

Mark-

You posted in the Single Driver thread some time ago that I would prefer the BR enclosure to the rear horn. Have you seen the thread lately? You were right. The BR enclosures are so sweet, I dismantled the rear horns and took 3 pair of RS 40-1197 drivers and built 5 BR enclosures. Four are alike and will be used in the QD-1 experiments.

Of course, when I find a QD-1, I'll need to open it up, clean it and refresh some of the parts.

[DizRotus]

One (two drivers) is an iPod Dock on steroids (see "Bluetooth iPod Dock

on Steroids at

http://forums.klipsch.com/forums/t/175146.aspx).

No way to use a QD-1 with this, but the 4 matching speakers should be

interesting. Now I just need to locate a serviceable QD-1.

[whatever55]

http://www.sound.westhost.com/project18.htm

Some more information