The dbx 2 Encoded LP. A Rarity of Superb Fidelity

TLS Guy

TLS Guy

Seriously, I have no life.
This is a post from the museum section of my AV room.

The dbx encoded LP is seldom talked about, however it was an overlooked technology that equals the CD and in some aspects surpasses it.

In 1971, the dbx system appeared in competition with Dolby. In my view it was superior. It was a professional format to increase the dynamic range of master studio recordings and lower the noise floor. I was an early adopter, and was making professional recordings at that time, 1973 actually.

Later the domestic dbx-2 code encode system was introduced as a domestic format. The original professional format became dbx-1.

In 1972 a version of dbx-II was introduced to encode LPs. To play the LPs, the decoder had to be placed in a tape loop.

No significant number of encoded discs appeared until 1977/1978 time frame. As digital techniques appeared dbx encoded discs faded rapidly after 1982, and was gone entirely by 1984. No significant number were produced after 1982. So it had a short life in the sun.

However as a medium it delivered. The dynamic range achievable is 120 db. This bests CD by 30 db, and is comparable to SACD and high bit rate PCM and Bitstream.

The surface noise is totally inaudible. The distortion is markedly reduced, and not audible on the inside grooves, as the disc modulation can be substantially reduced.

I have a few dbx II discs and a few open reel encoded 7.5 ips encoded commercial reel to reel tapes.

Here is a picture of a dbx-II encoded LP.



Here is a picture of my Quad 44 preamp, with the disc button activated and the Tape I monitor loop red light glowing. The Quad 44 has two tape monitor loops, so that you can dub from two three head tape machines in both directions, and off tape monitor in both those directions. This is just another example of how Peter Walker's genius always got it right, and makes his units so valuable today. Since he was such a stickler for product reliability, his gear can still be enjoyed and put into service by many. No wonder his gear continues to rise in value even against inflation.



Hear is a picture of my dbx-II NX-40 which can decode both dbx-II encoded tapes and LPs.



This is now a little known by-way in the history of the LP. It was capable of truly superb reproduction.
 
3db

3db

Audioholic Overlord
Its funny that you bring that up Mark. I was exposed to it in my teens having heard some dbx encoded vinyl. It was awe inspiring to say the least.

All my Yamaha cassette decks are equipped with dbxII facility and I use it religously in recording. Some detractors say they hear a pumping affect with dbx but I have yet to encounter it. I have recorded all genres of music to try and capture the pumping affect but havent been able to reproduce it. I had a few friends over and switched back and forth from the CD source and a tape copy made on a chrome tape with dbxII and they could not tell the difference.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Its funny that you bring that up Mark. I was exposed to it in my teens having heard some dbx encoded vinyl. It was awe inspiring to say the least.

All my Yamaha cassette decks are equipped with dbxII facility and I use it religously in recording. Some detractors say they hear a pumping affect with dbx but I have yet to encounter it. I have recorded all genres of music to try and capture the pumping affect but havent been able to reproduce it. I had a few friends over and switched back and forth from the CD source and a tape copy made on a chrome tape with dbxII and they could not tell the difference.
The problem with these noise reduction systems, is that there has to be no change in performance between record and playback. In dbx, especially dbx-1 frequency response errors are doubled. So that makes it a problem sharing tapes with other machines. The most resistant to this is Dolby B, which is why it was so popular.

With dbx-1 you had to keep your machines in perfect running order, or you would have serious frequency response error and even pumping.

That also applies to dbx encoded discs. You have to make sure you cartridge has exemplary performance, otherwise you have doubling of frequency response errors. Fortunately I have a Shure V V15 xmr, in and SME series III arm, so everything works as it should.

With Dolby all forms, A,B and C are level sensitive, and record level has to be set to the specified Dolby level.

I have an reel to reel Dolby B decoder, and you have to set playback to the reference level, using the test tone at the start of each tape, and setting it by the meter on the Dolby unit.

I will do a post on this at later time.
 
3db

3db

Audioholic Overlord
The problem with these noise reduction systems, is that there has to be no change in performance between record and playback. In dbx, especially dbx-1 frequency response errors are doubled. So that makes it a problem sharing tapes with other machines. The most resistant to this is Dolby B, which is why it was so popular.

With dbx-1 you had to keep your machines in perfect running order, or you would have serious frequency response error and even pumping.

That also applies to dbx encoded discs. You have to make sure you cartridge has exemplary performance, otherwise you have doubling of frequency response errors. Fortunately I have a Shure V V15 xmr, in and SME series III arm, so everything works as it should.

With Dolby all forms, A,B and C are level sensitive, and record level has to be set to the specified Dolby level.

I have an reel to reel Dolby B decoder, and you have to set playback to the reference level, using the test tone at the start of each tape, and setting it by the meter on the Dolby unit.

I will do a post on this at later time.
These machines are equipped with dbx2, NOT dbx1 and arent subject to the same problems as dbx1. I share my cassettes across 4 different Yamahas and a dual well Pioneer. Except for the Pioneer which needs service, the sound coming out of all machines are identical to the machine that recorded it.
 
Eppie

Eppie

Audioholic Samurai
My first exposure to dbx was through VHS tape players/recorders. NEC made a VHS unit with dbx-II support and the audio recordings were superb. The main drawback was that they were rare and you could not play the tapes on a non-dbx unit. The recordings were heavily compressed and naturally required the proper decompressor for playback. Dolby would help but only partially. The audio on HiFi VHS decks was already very good but dbx raised it to another level.

HiFi on VHS is not just a general term like hifi audio but a specific feature. Standard VHS units use the edge of the tape to record audio, like a cassette player. HiFi VHS units record the audio in the same helical fashion as the video, vastly improving audio quality. Add dbx noise reduction to that and you have a unit that approaches digital audio tape (DAT) in quality. You still have the slow seek and rewind issues but the quality was definitely there.

I did not use this format a lot, but it was very handy for house parties. While video quality would degrade at slower recording speeds, the audio did not. A standard 2 hour tape plays for 6 hours on the slow speed. I would record 6 hours of mixed music on one VHS tape and you basically have music for the entire evening without having to touch anything.

I also recorded with a band that used a helical recording unit with their mixer. The tape size was closer to Betamax, which is smaller than the VHS standard, but the unit used the same style flying tape head as VHS tape units and the quality was very good. You could overdub and move tracks with no noticeable loss in quality, although I am sure there would have been some limit as to how may times a track could be copied before artifacts would start to creep in. The big benefit with digital is that you can instantly move to any place within a track and make unlimited perfect copies. Can't recall if that recording mixer had some form of noise reduction but I imagine it would have to produce such good quality demos.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Its funny that you bring that up Mark. I was exposed to it in my teens having heard some dbx encoded vinyl. It was awe inspiring to say the least.

All my Yamaha cassette decks are equipped with dbx-2 facility and I use it religiously in recording. Some detractors say they hear a pumping affect with dbx but I have yet to encounter it. I have recorded all genres of music to try and capture the pumping affect but haven't been able to reproduce it. I had a few friends over and switched back and forth from the CD source and a tape copy made on a chrome tape with dbxII and they could not tell the difference.
I understand that, but I have dbx-1 and dbx-2 units. The dbx-1 units are my original 157 unit, which is not installed currently, as prior to the move and the new studio, I managed to snag a 19" rack mounted dbx-1 150X which was unused new old stock. That was a great find. For open reel pro use dbx-1 or Dolby A are mandatory.

I also have a mastering quality TEAC Z6000 cassette deck and that has Dolby B and C as well as dbx-2. And I have the off board N-40 dbx-2 unit which also has the disc decoder, and a tape decoder as well. I also have a 19" rack mounted NAK MR 1 which has Dolby B.

What I'm saying is that your results are good, as you are recording and playing back on the same machine. I don't know if it is two or three head. But either way even if it is three head, the playback and record heads are usually in the same housing in Cassette decks. So there won't be an Azimuth issue between record and playback. However play it back on another machine and the slightest azimuth error between the two decks will play havoc. I can assure you of that. Dolby B is much more tolerant, but not as powerful.
 
davidscott

davidscott

Audioholic Ninja
Thanks for the post. I never owned a dbx cassette deck but heard the noise about playing a dbx recorded tape on any other deck would cause sound problems. I believe "breathing" was the word back in the day. Also, thanks for the info on the dbx recorded LPs. Never had one but it sounds like it was awesome. I wonder how the dbx decks would compare to a good deck with dolby s and hx pro.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Thanks for the post. I never owned a dbx cassette deck but heard the noise about playing a dbx recorded tape on any other deck would cause sound problems. I believe "breathing" was the word back in the day. Also, thanks for the info on the dbx recorded LPs. Never had one but it sounds like it was awesome. I wonder how the dbx decks would compare to a good deck with dolby s and hx pro.
It was known as pumping back in the day. In order to use dbx, especially 1 and to a great extent 2, and also Dolby A you had to keep your machines in absolutely tip top condition, which meant maintaining an extensive service bay, including certified laboratory tapes.

I can't begin to tell you how much easier a Digital Audio Workstation is!
 
davidscott

davidscott

Audioholic Ninja
It was known as pumping back in the day. In order to use dbx, especially 1 and to a great extent 2, and also Dolby A you had to keep your machines in absolutely tip top condition, which meant maintaining an extensive service bay, including certified laboratory tapes.

I can't begin to tell you how much easier a Digital Audio Workstation is!
My bad yeah it was pumping. :)
 
3db

3db

Audioholic Overlord
I understand that, but I have dbx-1 and dbx-2 units. The dbx-1 units are my original 157 unit, which is not installed currently, as prior to the move and the new studio, I managed to snag a 19" rack mounted dbx-1 150X which was unused new old stock. That was a great find. For open reel pro use dbx-1 or Dolby A are mandatory.

I also have a mastering quality TEAC Z6000 cassette deck and that has Dolby B and C as well as dbx-2. And I have the off board N-40 dbx-2 unit which also has the disc decoder, and a tape decoder as well. I also have a 19" rack mounted NAK MR 1 which has Dolby B.

What I'm saying is that your results are good, as you are recording and playing back on the same machine. I don't know if it is two or three head. But either way even if it is three head, the playback and record heads are usually in the same housing in Cassette decks. So there won't be an Azimuth issue between record and playback. However play it back on another machine and the slightest azimuth error between the two decks will play havoc. I can assure you of that. Dolby B is much more tolerant, but not as powerful.
All 4 decks are three head machines. My main recording deck is now a Yamaha KX-1200 and tapes mades on it and played on my two Yamaha KX-800 and Yamaha K1000 sound like they sound when played on the KX-1200. I do look after them.
 
davidscott

davidscott

Audioholic Ninja
My first exposure to dbx was through VHS tape players/recorders. NEC made a VHS unit with dbx-II support and the audio recordings were superb. The main drawback was that they were rare and you could not play the tapes on a non-dbx unit. The recordings were heavily compressed and naturally required the proper decompressor for playback. Dolby would help but only partially. The audio on HiFi VHS decks was already very good but dbx raised it to another level.

HiFi on VHS is not just a general term like hifi audio but a specific feature. Standard VHS units use the edge of the tape to record audio, like a cassette player. HiFi VHS units record the audio in the same helical fashion as the video, vastly improving audio quality. Add dbx noise reduction to that and you have a unit that approaches digital audio tape (DAT) in quality. You still have the slow seek and rewind issues but the quality was definitely there.

I did not use this format a lot, but it was very handy for house parties. While video quality would degrade at slower recording speeds, the audio did not. A standard 2 hour tape plays for 6 hours on the slow speed. I would record 6 hours of mixed music on one VHS tape and you basically have music for the entire evening without having to touch anything.

I also recorded with a band that used a helical recording unit with their mixer. The tape size was closer to Betamax, which is smaller than the VHS standard, but the unit used the same style flying tape head as VHS tape units and the quality was very good. You could overdub and move tracks with no noticeable loss in quality, although I am sure there would have been some limit as to how may times a track could be copied before artifacts would start to creep in. The big benefit with digital is that you can instantly move to any place within a track and make unlimited perfect copies. Can't recall if that recording mixer had some form of noise reduction but I imagine it would have to produce such good quality demos.
If I ever want to record anything to tape again, I will use my Toshiba combo DVD VHS hify with TDK videocassettes. I doubt I will but it's nice to have the option. Thanks for the explanation on how VHS recording works.
 
rjharle

rjharle

Audioholic
Thanks for the post. I never owned a dbx cassette deck but heard the noise about playing a dbx recorded tape on any other deck would cause sound problems. I believe "breathing" was the word back in the day. Also, thanks for the info on the dbx recorded LPs. Never had one but it sounds like it was awesome. I wonder how the dbx decks would compare to a good deck with dolby s and hx pro.
I recorded my vinyl onto Maxell MX Metal cassette tapes using a Nakamichi 680ZX encoded with DBX. The tapes sound just as good today as they did 40 years ago. IMO, when I audition tape decks and encoders, the comb. I chose sounded superior to any Dolby. Not unlike the VHS Betamax wars; I believe had it not been for licensing costs, we would've all be listening to DBX. I, too, tried to get as much DBX LPs, but there just wasn't that many on the market (like Betamax tapes)

Had to go to Direct to disc and Half Speed Master LPs.
 

Latest posts

newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top