Really new to this and question on Dynaco Quadaptor?

[jpchleapas]

Hey Gang I am trying to set up a very simple pair of rear speakers for my Dad. The new wood floor is going in next week in his living room. We will have two recliners sharing the sweet spot in his living room to watch TV and listen to his stereo. Has anyone here had any first hand experience with the old Dynaco Quadaptor? This device is not supposed to add anything to the sound. It was designed to allow rear speakers to be added to a stereo back in the good (or bad) quad audio days. His stereo consists of two 6' tall 2-way horns. The HF are JBL 2360A 31" x 31" biradial horns. These were designed for movie theaters and pro audio. They are a great sounding horn to my ears. I have tad td-4001 drivers in them. The bass bins are humble JBL 4648a-8. Each bass bin has 2-15" woofers. The amps are mono block in Klimo el34 push-pull for the bass bins and the horns have Welborne 45 DRD tube rectified mono amps. The crossover is a marchand xm-126 vacuum tube one. The DVD/CD transport is a Muse model 9. We are going to go with a 50" LCD type monitor for the screen. Now I am seriously considering the Dynaco Quadaptor to add a pair of rear speakers. This set up will not be SOTA but I just want to be able to add rear sound to his set up. I can disable the Quadaptor when just listening to his stereo. I am considering a pair of "The Cinema Music Channel" speakers by Classic Audio Reproductions. This is the company that makes the nifty JBL Hartsfield reproduction speakers. Anyway what to you guys think about the Quadaptor? All I want is a way to add rear speakers that will not add anything synthetic for sound reproduction to what comes out of my amps and crossovers. I am open to any suggestions folks. I love my tube amps but am new to home theater. Thanks for taking the time to read this. Below is a link describing the quadaptor. John C.

http://home.indy.net/~gregdunn/dynaco/components/QD1/

 

[RichPA]

I've owned one of these for decades now, and have used it off and on over the years. It can give a very pleasing effect, and will to some extent "decode" the rear channel sound present for Dolby Pro Logic recordings. Some important lessons (in order of importance):
1. Make sure the amp will tolerate a common-ground connection between channels; if not, you may damage the amp
2. If at all possible, make sure that the rear speakers are at least as far away from the listener as the front speakers; otherwise, too much of the sound may be localized at the rear.
3. Adjust the rear level carefully; too high a level will spoil the effect.

Just out of curiousity, where did you find one of these?

 

[jpchleapas]

Hi Rich. I see them listed for sale on ebay. I heard about these for the first time from a post at AA a few days ago. I figure it is easy to buy and try it to see how it works since they are well under 100. LOL, they listed for the princely sum of $29 brand new. I am kinda sorta scratching my head to figure out how to wire it into my stereo. I have 4 mono block amps feeding my two speakers with 2 - 45 SET amps for HF and 2 - 300b SET(or two pp el34) for my bass bins. Then there is the 2-way marchand tube speaker crossover to deal with. Still it should be worth a try. I am seriously considering buying a pair of Classic Audio Reproductions smaller speakers for the rear speakers. Thanks for your input. John C.

 

[RichPA]

Actually, when they were new you could buy one in kit form for $19.95

I don't think you'll be able to get this to work with monoblocks, especially given the active crossover setup you describe. If you look at this web site - http://kantack.com/surround/ - you can find the wiring diagram. The link labeled "Passive Matrix Decoder Utilizing A Phantom Center Channel" shows the wiring diagram used in the Quadaptor. I am no expert on tube amps, but I don't think you can wire the amps together in the way indicated by this diagram - you might pose this question on the tube forum.

Another way to achieve your goal is to buy an inexpensive old Dolby Surround decoder (from the days before Pro Logic and Dolby Digital). Many of these had a "matrix" setting that does the same thing as the Quadaptor, but at line level. You would just need to tap your pre-out signal. Some of these have built-in rear channel amps, others require an external amp.