Introduction of myself and Philips RH832 Quadra Receiver (1973)

[Thomas]

Hello Quadlovers

My name is Thomas and I'm from the Netherlands. With my 28 years of age I am convinced I was born at least 20 years too late; missed the wonderfull glory days of true analogue sound; buying records instead of videogames and listening to Pink Floyd instead of Lady Gaga. Cleaning your stylus like it was at least as precious as a few weeks of hard labor and swiftly run to the store for this month's new "Elektor" which features a very cool MOSFET power amplifier whose parts will be at least another two months worth of saving up. Well, in those days, it was! At least, I guess so or I like to think so

I've been aware of Quadraphonicquad.com for a while now, but Quadraphonic sound has always been kind of a sidetrack for me. Until recently my interest in this matter has been quite low; mostly due to the minor availability and high prices of those QS and SQ modulated vinyl frisbees

I have, however, a born addiction for vintage and analogue sound. For more than ten years now, I run my website www.mfbfreaks.com which focusses exclusively on the dutch Philips brand in the period of 1969-1979. That is, before "plastic fantastic" started to spread through the market. The so called "Motional Feedback" system was very, very revolutionair back in 1973. It combined two worlds which until then were unthinkable to go together. By implanting a piezo electric sensor in the woofer of the loudspeaker cabinet, Philips was able to feed the actual cone movement back to the amplifier where it was compared with the original source signal and, if necessery, corrected. This way it became possible to greatly reduce the resonance frequency of the woofer and, thus, greatly improve bass response in the 20 - 60 Hz range. In normal English, a relatively small speaker was able to produce the sound that would normally require a cabinet at least two or three times its size, with accompanying bigger woofer. A miracle was born! Philips also decided to build the power amplifier inside the cabinet, making this an active loudspeaker system. One of the first for home use, that's for sure! Built-in filters, sensitivity control and built-in automatic power control were added and there it was; Philips Motional Feedback Loudspeakers; Small in size; Big in performance! How wonderfull is that?



The model shown above, 22RH532, was released in 1973. And now it gets interesting also for you guys In those days, Quadraphonic Sound Reproduction was a great novelty. Although hesitantly gaining popularity because of all those different methods and media, Philips also saw a chance to use the brand new MFB (Motional FeedBack) techniques to be smoothly integrated into this super duper modern reproduction system. Where other brands had to struggle building large and heavy receivers with multiple power amplifiers in a back breaking device, Philips didn't need all that; they had their amps ready integrated in the speaker cabinets!

Theoretically they could simply take their already popular and famous GA212 record player...



...add two stereo MFB preamps type 22RH551 with those great round VU meters...





...maybe add an AM-FM tuner for fun, like the 22RH651 they already had hangin' round...



...stirr and shake a little so a smooth blend of 1973 High Tech Audio Equipment is created and, voila...



There you have it! The Philips 22RH832 Four Channel High Fidelity Quadraphonic AM-FM Stereo Receiver Record Player with built-in 4-channel MFB pre-amplifier, SQ decoder and - hence the commercials - send/return DIN plug for the use of an external CD4 decoder! Well, if that's not gonna make daddy drool all over the place, what else will? Not even the newest DAF 66 with variomatic Sports Edition! Its built-in decoder offers instant SQ decoding but since the Shibata shaped stylus with special GP422 "Quadro" cartridge was added, also CD-4 decoding is prepared for. All you needed was an external, third party decoder. Probably a copyright issue; anyone know anything about that?

So far, so good I've been loving, collecting and serviceing (is that even a word?) vintage Philips audio for about ten years now and, although the 22RH832 receiver entered my collection years ago, I only now am really really wanting to actually hear that Quadraphonic sound! I am currently working on two RH832's for repair; one for a friend in Italy and the other one I recently bough for parts but it turns out to be too good to just cannibalize. A third (of fourth?) one is also on the way. Triggered by all that Quadrapower, I decided to get ready and get myself some Quadra records. Already have hundreds of normal LP's but the Quadras are by far in minority. Mostly because you never seem to find anything reasonable in a flea market. "Tango d'Amour" or "Hammond a Gogo" is hardly something you'd like to hear in Stereo, let alone in Quadro!

I swiftly mentioned Pink Floyd before, but in my humble opinion they are by far the most fenomenal band ever in progressive Rock history. True, Led Zeppelin did great, true, Deep Purple rocks, but the psychedelic Floyd sound was never surpassed by anyone. If only they had had Jefferson Airplane's Grace Slick before she overdosed, that would be a real match maker Would sure like to hear her perform "Astronomy Domine". But I'm drifting away from the subject
Recently purchased Atom Heart Mother in SQ, didn't even know it existed! Haven't played it yet, need to set up my Quad System soon. Accidently I also stumbled into Dark Side of the Moon in SQ, mixed by our beloved mister Alan Parsons. Great guy he is. It's being shipped from Australia as we speak, hope to have it here soon in one piece. Now I also read about Wish You Were Here and sure, need to have it Read about poor quality of this record, not specifically the SQ mix. Anyone know anything about that?

Well, that's enough of an introduction for now I guess Have fun reading and, hey, the pics are clickable so no need to go find your glasses

Regards!

Thomas Baur
webmaster http://www.mfbfreaks.com
The Ultimate Philips Motional Feedback Website!

 

[Doug G.]

Hi Thomas,

That is also my brother's name.

Welcome to QQ and I'm sure you will become one of us who can no longer listen to two channel stereo after experiencing quadraphonics. There have been times in my life (a lot, actually) I was forced to but I wasn't happy about it. \:^)

And no, "serviceing" is not a word but "servicing" is. \:^)

Anyway, that looks like some interesting equipment there. Philips has always been an innovative company. I remember the motional feedback concept/adaptation back in the seventies. Didn't other companies give it a try also?

Keep us informed of your quadraphonic exploits.

Doug

 

[Carroll]

Thomas.

I am a new member also. So, welcome to us!

In reply to Doug's question "Didn't other companies give it a try also?". This concept is very much alive. Velodyne uses an accelerometer, on their higher priced subwoofers, for bass response correction.

Back in 1977 I had the outboard Panasonic CD-4 converter. It came with a calibration record and you could very accurately dial in the turntable variables (anti-skate), as well as the 45kHz carrier frequency. I still have some surround sound vinyl.

Presently, I am trying to get back to multi-channel sound. I have 6 Luxman MB3045 tube amps and 1 Bogen MO-100A tube amp. With all the multi-channel Media now available it is much more attractive than the first time I tried this (back in the early 70's)

My front channels with center are two JBL 4530 scoop horns fitted with Tannoy 3859 dual concentric drivers. The center channel is an original Tannoy 'Cougar' wedge monitor (also 3859). Left and right rears are ESS AMT-1B Heil driver speakers(true Di-Poles).

Everything is very efficient so I expect to have tremendous reserve for dynamics.

 

[Thomas]

Hi Thomas,

That is also my brother's name.

Welcome to QQ and I'm sure you will become one of us who can no longer listen to two channel stereo after experiencing quadraphonics. There have been times in my life (a lot, actually) I was forced to but I wasn't happy about it. \:^)

Hi Doug,

Hmm, I wonder if I will become as addicted to quadraphonic sound as much as I am to analogue stereo sound I believe back in the Seventies when the quadro system was introduced, people looked at it differently as we do now. These days every audio equipment manufacturer or recording engineer tries their best to come as close as possible to reality; close mic recording is used for rich detail in recording and linearity and dynamics are the key in audiophile reproduction. Back when Quadro was a hot new thing, it was used to "show" you as many tricks as fitted on one record side. Although I haven't heard any original recording yet, I have been reading around a bit. Guitars don't come from the rear in real life, vocals don't swirl around your head and neither do pianos.

One of the few engineers who really got that was Alan Parsons, as stated in the article "Four Sides of the Moon". He states that "The reverberation system used throughout the quad reduction was two EMT reverb plates: one was spread across the front channels and one across the rear – both fed from the same source. This gave a very full ‘inside the chamber effect’ and helped to minimize the ‘hole in the middle of the room’ caused by the absence of direct sounds there."

Although he also played around with instrument positions, for example: "The bass guitar also had to remain center front for the sake of the SQ, but this was no great problem as bass frequencies have little directional characteristics and the harmonics and attack of the instrument are not particularly strong here. Guitar was placed rear left and the electric piano rear right."

The above meaning, in short, Quadra was used in the beginning mainly to show off to the audience. A sign of "can you hear all that amazing stuff we can do?" . All those things had little to do with realistic sound reproduction in my opinion.

If we look at the introduction of Dolby Surround, 5.1 channel audio and DTS for instance, a complete different approach is taken. The goal here is to closely reproduce events from real life. Think of flying airplanes, bullets, cars driving by etc. Everything in order to approach the live experience as close as possible. No amazing "wow, do you hear that chainsaw in the rear left?"

Therefore I, for now, don't yet know what to expect from Quadraphonic sound reproduction. Really need to get some material and setup my system

Anyway, that looks like some interesting equipment there. Philips has always been an innovative company. I remember the motional feedback concept/adaptation back in the seventies. Didn't other companies give it a try also?

Yes, certainly they did. I will explain later when I also anwer to...

In reply to Doug's question "Didn't other companies give it a try also?". This concept is very much alive. Velodyne uses an accelerometer, on their higher priced subwoofers, for bass response correction.

Carroll Yes, other companies experimented with accelometers as well. When Philips released the system, two other companies soon copied the idea using - surprisingly - original Philips units to build their own Motional Feedback speakers. They were Jamo (Models MFB200 and MFB300) and Restek (models Laser and Optima). Later on, other manufacturers also designed actively controlled systems. Korn & Macway created their "Servo Feedback" system which combined the use of a passive co-woofer with some sort of accelometer built-in. Bang & Olufsen is said to also have used this method to build some sort of active controlled speaker system.
Later in the 1990s Sony released their MHC7900 audio system with active speakers which featured ribbon tweeters and Motional Feedback woofers.

Apart from home audio, several Pro-Audio manufacturers also have used several forms of active speaker control. The dutch Stage Accompany brand had Philips design their "Blue box" which features a woofer with Motional Feedback. Of course, active speaker control is a widely used thing. These days it is mostly applied in some DSP form with parameters read from the coil temperature, inductance, current and things like that. Due to practical limitations (being the expensive modification of the woofer, extra signal cable from woofer to amplifier) I think Motional Feedback is not generally used anymore. The fact still remains that it is a revolutionar thing though

Back in 1977 I had the outboard Panasonic CD-4 converter. It came with a calibration record and you could very accurately dial in the turntable variables (anti-skate), as well as the 45kHz carrier frequency. I still have some surround sound vinyl.

Presently, I am trying to get back to multi-channel sound. I have 6 Luxman MB3045 tube amps and 1 Bogen MO-100A tube amp. With all the multi-channel Media now available it is much more attractive than the first time I tried this (back in the early 70's)

My front channels with center are two JBL 4530 scoop horns fitted with Tannoy 3859 dual concentric drivers. The center channel is an original Tannoy 'Cougar' wedge monitor (also 3859). Left and right rears are ESS AMT-1B Heil driver speakers(true Di-Poles).

Everything is very efficient so I expect to have tremendous reserve for dynamics.

Wow, that's a nice setup Although JBL (and Altec Lansing as well) are not generally know for their home audio here in Europe but I have seen a lot of their wonderfull equipment thanks to the internet. The whole tube-amps-and-high-efficiency-units thing I find very fascinating as well. I have a few Philips tube amps, the most impressive one being the AG9018 with its 2 x 25 watts OTL design. The famous 8" unit 9710 in 800 ohms is a very, very good match with it. I currently have a pair in the original cabinets but many great designs were made with this unit, varying from open baffle to Schmacks horns. No room for those, though Would make a nice quadro setup with 2x AG9018 and 4x 9710

Regards!

 

[phydo]

Thomas:

Welcome aboard. Be forewarned – Quadraphonic’s is a sweet addiction!

Justin

 

[JonUrban]

Welcome to both of you new members, and new "Quad Guys"! Hope you can get some info from QQ and our members. Glad to see y'all here!