Decoding SQ with Dolby Pro Logic (I not II)

[radioheadrox]

I will start off this post by saying that I've been a long time admirer of quad from the sidelines, but I have only recently become very interested in quad. I will also say that I missed out on quad since I am only 15.

A few years ago I became a serious record collector around the same time that I became a huge Pink Floyd fan. When I discovered that a few of their albums were released in quad, I set out to acquire the quad mixes. I recently acquired a copy of the dark side of the moon in quad. For a while, I've also been looking for a decent way to experience SQ quad. I have my dad's old receiver however he bought it in 1972 and it has a gawdawful non-logic SQ decoder, so I decided to research the various SQ decoders that exist. I then concluded after reading about the famous Tate that I'd never find one or afford one. However, at the same time, I discovered that Dolby Surround Pro-Logic (I not II) system was based on SQ. So I decided to conduct an experiment.

Now, I know that Dolby Surround is terrible for music because the rear channels have a frequency rolloff and I also know that the rear channels were monoed to allow the centre channel encoding. But after conducting my experiment, I discovered that Dolby Pro-Logic I does a good job at decoding SQ (at least in my 6 year old JVC receiver). I happened to have a SQ sampler record that contained Chase's Open Up Wide. I read on Tab Patterson's website that a single trumpet travels around the speakers, one at a time. I played the song, and ta-da! it decoded perfectly (great front/back separation) with the exception of the rear channels being monoed. In my attempt I first turned the centre channel down, and then the second time I turned the centre channel into 'phantom' mode.

I know that my system isn't perfect, but it allows me to enjoy my SQ quad records much more than if I played them through my non-logic joke of an SQ decoder. I know that I should probably get a better SQ decoder, but I don't have the time or money to search for one.

If you are a newbie to quad and can't find a decent SQ decoder, I suggest trying a Dolby Pro-Logic I decoder (but not a ProLogic II decoder, these are excellent for QS though).

Wow, that was a very lengthy post. I didn't mean for it to get this long!

Thanx for reading,
James

 

[JonUrban]

Hi James,

Welcome to the place, and we are glad to get the "younger" quad fans to stop by! Most of us older guys were there ourselves, being young and broke, and patching together systems that we could barely afford. Fear not, you are doing fine!

I have a question regarding your login. Are all of these yours?

radioheadiscool
radioheadrocks
radioheadrox
radioheadrox123
radioheadrox2002
radioheadrox456
radioheadvinyl

If so, let me know so I can delete the ones you do not want to use. I would prefer that we have an acurate count of members.

Another thought. Do you have a receiver that does DTS? That is probably the best way to experience the "old quad". If you do, let me know. I could send you a disk or two!

:-jon

 

[radioheadrox]

oops, sorry about all those names, I do think that all of those radiohead names are mine.

When I tried to sign up, the system kept rejecting names. I remember trying those ones, I think I was having internet problems that day that were preventing me from completing the sign up...could you please delete them (all except radioheadrox2002, this is the one that I am using)?

I also think that there are some ones like "pinkfloydrox" and "pinkfloydquad" that are mine that I tried to register.

Again, I am sorry.

No, I do not have a receiver that does DTS. My surround reciever only does Pro-Logic (it is pretty old). However, I do have PowerDVD 4 on my computer and I have a SB Live! card. So I can play DTS, but I need to buy better speakers for my computer. My only other option is to output the DTS cd from PowerDVD using the Dolby Surround encode function. I have tried this and it does work, but it is no better than playing SQ discs directly through the pro-logic decoder.

James

 

[Cai Campbell]

Yo, RadioHead, welcome to the forum!

I must say that using DPL is a very poor way to enjoy your SQ quadraphonic recordings. Even a non-logic SQ decoder is going to give you better performance. DPL might provide more separation than non-logic SQ, but the soundstage will be all messed up.

Don't give up on finding a decent SQ decoder. It doesn't have to be a Tate, but just about anything will be better than DPL, that's for sure. Look for Lafayette SQ decoders. They can sometimes be found for cheap and all of their models are better than most.

Good luck!

 

[radioheadrox]

I disagree that using my non logic SQ decoder provides a better experience. I tried it once and it was terrible. I tried playing Chase's Open Up Wide through it, and even though sounds generally went in the right places, they also went pretty much everywhere else at the same time! (Almost as bad as four channel mono, woohoo!)

I know that in DPL the sound won't be anywhere near perfect, but it does work pretty well. I have Simon and garfunkel's Bridge over troubled water in SQ quad, and in the song baby driver, you can really hear the car sound effects drive around you (when I played it in DPL). When I played it through my SQ decoder, the effect was pretty much absent (at least the RM decoder in the receiver is decent). The quad effect is cool, but I can understand why SQ didn't take off. My dad bought this reciever in 1972 and at the time, it cost half the price of his university tuition! Yikes!

As for finding a decent decoder, I don't even know where to look. I don't want to try ebay as most people won't ship to Canada (receivers are heavy and postage is expensive!).

James

 

[Cai Campbell]

Okay, so you have a really, really crappy SQ decoder then. There may actually be something wrong with it. Before I bought an SQ decoder, I played a lot of SQ stuff through DPL and I thought it sounded pretty bad. But hey, as long as you like what you're hearing, that's what counts!

 

[The Quadfather]

If he has one of the Pioneer receivers, their decoders were pretty bad. I went from that to an Audionics Space and Image Composer (Tate). Imagine my shock in the fact that the SQ system actually works! You can find Fosgate 101A (Tate) on Ebay occaisionally, but you must be willing to lay down some cash for it. It is doubtful you will see a Composer, as there were only about 200 made. You might could find a Sony SQ decoder, I understand they were OK, but the Lafayette units were better. I have actually heard neither in a quad setup, so I am passing along the word of others, and having a Composer, I am spoiled anyway. I did have a Pioneer QX4000 and it was awful on separation. A better way to listen to LPs in quad if you don't have the bucks for a good SQ decoder, is to get set up for CD-4. A CD-4 demodulator can be had for a modest price, and can be easily connected to your receiver through the auxillary jacks. Another thing you can do is to try to find a Sansui QRX series receiver. It will have a Variomatrix decoder for QS, and a CD-4 demodulator built in. Note that CD-4 requires a special cartridge and stylus. The Audio Technica AT331LP will serve well, and do it cheaply. It also requires that the turntable has low capacitance wiring, which most quality quad era turntables had. You can tell by the thick signal lines. Happy Hunting!

The Quadfather

 

[radioheadrox]

Thanks guys for all of your advice.

My dad's receiver is a Toshiba SA-304. It has a RM and a crappy SQ decoder, as well as a couple of four channel inputs (for Q8 and quad reels I guess, or for attaching an outboard decoder or CD-4 demodulator).

 

[dr8track]

Radiohead,
I wanted to refer back to Cai's suggestion about finding an external SQ decoder. Yes, it's true that the Tate is extremely expensive and pretty difficult to find. However, I think Cai's suggestion about the Lafayette SQ decoders is a good one. They are excellent decoders. I found a Lafayette SQ-W decoder at a thrift store for $5. It does a great job decoding SQ. Also, concerning your shipping worries, it's actually very small in size. It probably measures about 7" wide by 6" deep by 3" high. It doesn't weigh much at all. Shouldn't cost you a fortune to ship.
Your best bet for finding one would be on Ebay. Just be persistent and keep checking. I don't think they are in great supply on Ebay, but you should be able to find one eventually and I don't think it would be real expensive.
Good Luck

 

[quadjoe]

Hi! Just wanted to add my 2 cents worth to this discussion: I have tried DPL for my SQ discs and overall I find it disappointing, although it does seem to be ok for ambience. For the last year I have been using a Lafayette LR-220 receiver with built in SQ and RM decoder, and even though it is a low-powered unit it does a very good job of decoding my SQ discs. By the way, the RM setting is labelled "Composer", I have been using it for my QS discs with excellent results as well as synthesizing quad from stereo sources (which is what the owner's manual recommends). If you keep looking you may be able to pick up a Lafayette reciever on eBay for a very reasonable price. Lafayette was one of the companies that really pushed the SQ system, and their receivers were among the first to offer logic (and later full-logic) decoders at a reasonable price. They were very under appreciated in their day.

 

[bmoura]

Jim Fosgate, who designed Pro Logic II for Dolby Labs as well as the Fosgate Tate decoder (among others), said on AVS Forum awhile back that Pro Logic and Pro Logic II were not designed for proper SQ decoding. Presumably a Tate decoder would be a more accurate choice there.

On the other hand, for Pro Logic encoded material, I find that Pro Logic II is a dramatic improvement over Pro Logic. It's an upgrade to get on your next Home Theater receiver or processor if you don't have it already !

 

[The Quadfather]

By the way, "RM" stands for "Regular Matrix" and is a generic name for QS. Sansui allowed anyone to use QS on their receivers without royalties as long as they didn't call it QS or use the QS logo.

The Quadfather

 

[radioheadrox]

I don't have DPL-II on my receiver, but I do have the DPL-II decoder for PowerDVD, it really does an awesome job of decoding DPL stuff, as well as QS/RM, but not SQ

As for finding a better SQ decoder it may be harder for me because I don't know what was sold here in Canada. I doubt that Fosgate sold any Tate units here and I don't know about Lafayette (I hadn't heard about any of these companies before I strated to look around on the net for quad info about a year ago). The only places other than eBay that I can think to look are flea markets (haven't seen much there before) or Cash Converters (a very good chain of second hand stores, but I also doubt I'd find anything there).

BTW, does anyone have any QS/RM channel identification tests? I would like to test the effectiveness of my RM decoder.

James

 

[The Quadfather]

One of the guys that do DTS conversions might have a copy on CD of a test channel ID recording. I imagine that most of the Tate gear was ordered by mail in the same way I got mine. So, I doubt that it would be limited to the United States. It is doubtful you will be able to find a Tate anywhere but Ebay, it has been done, but not often. The likelyhood of finding a Lafayette decoder is better, but Lafayette went under during the seventies, which is probably why you never heard of them.

Incidently, I once saw an ad for a surround decoder kit in a kit magazine where they advertised that the kit was similar to the "famous tate decoder". I took it with a grain of salt and paid it no more attention than it's price indicated it deserved. The interesting part is that this was in the nineties, not the seventies or early eighties.

The Quadfather

 

[Cai Campbell]

Well, there's always the famous Quadrafile test disc, that I just happen to have on CDR...

www.greatgig.com/quad/quadrafile.htm

 

[sspsandy]

I wanted to have quad in my car, using a cassete deck for matrix encoded recordings, so I got a Rockford Fosgate RFQ5000 Pro Logic 2 Surround processor and ran it through a Sony XM 4 channel power amplifier/equalizer. The RFQ5000 allows you to switch off the center channel, diverting the information to the front channels. My understanding is that Jim Fosgate designed the same 6 decoder systems into it that the Tate has, so it will synthesise discrete 4 or five channels from a stereo source, as well as give you great separation on any matrix encoded recording. I first ran this unit in the 4-channel mode, and it gave me excellent quad in the car, nice distinct separation front to back, and clear side to side separation, even in the back channels. I am now running the center speaker fifth channel, and it acts as an anchor, primarily vocal and rhythm parts, with the other instruments and drums punctuating the music coming from the other 4 channels. So I would suggest that any new receiver that has Pro Logic 2 built in would do a fine job as a quad decoder, not quite the same decoding scheme as a Tate, but sharp and discrete nonetheless.

 

[sqdave1975]

I must admit I too have fallen into the DPL trap, in fact I took it one stage further by removing all the Dolby components from a JBL outboard decoder (i.e. the 7Khz bandpass filter, the analogue delay chip and the mono Dolby B chip). This left the Analogue Devices SSM2126 chip which houses the input autobalance, the dolby surround decoder, the adaptive matrix and finally the center channel control. Some SQ material does sound quite good using this method, with good separation, (AD reckon 25db across all channels), but I think the problem stems from the decoding process, which is different to SQ. The "Surround" channel is created by the difference of Lt and Rt (L-R). The "Center" channel is created by the sum of Lt and Rt (L+R). When playing SQ it does create some strange effects, the adaptive matrix doing it's best to decode the music. It's a shame that the decoder and the adaptive matrix is all contained in an I.C. otherwise I'd love to try and connect the outputs of a non-logic SQ decoder to the inputs of the adaptive matrix!!!
I am embarking on a project to see what makes a Fosgate 3601 360° Space Matrix tick, which out came after the Tate 101A. (which as you say are very pricy now!!) It is supposed to have a similar (but NOT interchangeable) DES circuit like the TATE.
I'll let you know how I get on.
P.S. Bridge over Troubled Water does sound quite good, especially on my modded DPL decoder
I too missed out on Quad first time around.
I was 4 in '79, just as it was fading gracefully away.....


Dave.

 

[ambio]

DPL does a more acuurate job (except for the rears) on SQ than DPLII (QS/ RM).The Lafayette SQ-W had a Composer (RM) which gave good Quad efects from stereo. However, DPLII is a great improvement.

I have a Cantares SP-1 which has the best SQ I have heard. The QS is much better than a RM Composer for movies & music.This Ambisonic decoder gives you a sound that does not seem to be coming from any particular speaker, but surounds you. All this without logic circuits. It gives a more subtle sound that is espescially good for acoustic music.