I want to make it abundantly clear, that I have had some success with CD-4 (quadradisc.) But recently much more failure, primarily due to two things:
1- sandpaper effect &
2- issues with old 70's era gear (hum)
When CD-4 works well, the results can be amazingly great. Very discrete mixes brought to life. But let's not fool ourselves, CD-4 is a
DEAD format for all practical purposes. I'm not aware of a single bit of hardware that supports/functions with it since the 70's (I'm sure others will correct me if I'm wrong here!)
Heck, even in the whole of this very niche QQ surround/Quad forum of supposedly over 10,000 members; I wouldn't be surprised if there're only a few dozen actively listening directly to CD-4 albums.
So when it comes to support for hardware, a grand search must be undertaken for places like
qrxrestore etc. that still have the knowledge and abilities to do the job right.
Long before I started working towards a CD-4 system of my own, I was a non-member lurker here taking in the knowledge the forum offered. And once I took the plunge and got into the forum, I found friends with similar interests to help me along and further my education. To date, I believe I've pretty much read most of what's offered here for CD-4 information. But that doesn't necessarily translate to a golden ticket of success. The struggle must be endured to get there.
It took me till my 3rd try at a turntable before I found one I liked and fit the bill. It's a Technics SL1200MK7. Then I had to find the right carts. I started with an AT440MLb and that did a decent job, but I felt a little more separation could be had, so I changed over to an older AT15S (Shibata) which I've been happy with, especially for CD-4. I still have a new AT VM740ML (MicroLine) to give a try; however that's one area I don't relish, is changing out carts and having to adjust/realign each time.
I've actively been buying CD-4 albums (primarily through sellers on discogs) in NM or better condition which is another added expense. Of course that's all part of the cost of the hobby, I don't really mind that, the hunt is an enjoyable aspect for me. I had a nice little stack built up and cleaned ready to go and Demodulate/Convert to digital also; when I discovered my QRX-8001 had a couple of new issues. First the Left Rear channel is cutting in and out, but I could still rip/convert the LP. Then I discovered it also developed some nasty hums (both a lower level and some higher toned hums.) Well the Sansui had already been gone over a couple years ago by qrxrestore along with the
Holy Grail alignment; I can tell you, along with the initial cost of the Sansui and the qrxrestore work (along with shipping costs for the beast) it ain't cheap folks! OK, so I'm not ready to send this back again to qrxrestore for more work. I can afford it just fine, I just hate all the tearing down of my system, packing up and shipping out, etc. etc.
So I decided to look for a stand alone Demodulator while I sit on the Sansui issue some more and chew on it. I found a nice Marantz CD-400B that was listed on eBay as a NOS, and it looked every bit of a new in box type unit. So I bid on it and got it for a measly $198 with shipping. Not bad, but I knew full well that even though it looked new in box, who knows what it's really been through and also that for a nearly 50 year piece of gear that doesn't count for much. But for that money, and feeling somewhat wanting of something right away I bit on it. Well it turns out it works pretty well except it too has a mild low level hum. I thought at first, after doing some research, and hearing some vocalization in the hum perhaps I have a ground loop issue. But, after doing some other testing on my setup of:
A: Recording a regular LP through a MOTU UltraLite mk4 with just my Technics SL1200MK7 and Rotel preamp,
no hum!
B: Recording a QS LP through a MOTU UltraLite mk4 with my Technics SL1200MK7 and through my Surround Master v2 for Quad, and again
no hum!
All that I've talked about here on the open forum is only a tiny tip of the ice-berg as to conversations I've had with very experienced and knowledgeable folks in private messages about my CD-4/Quad issues. They all have been very valuable friends and supportive in trying their best to help me out. I feel I am sooo very close to have it all working as it should, only if the old gear would hold up. But that's the rub right!
We're now working with the idea that the hum is possibly caused (the Marantz Demod.) by either
a dry joint or a failing electrolytic capacitor. None of that means much to me, as I don't have experience in working on electronics, and have no interest in learning at my advanced age. So now where does that leave me? I guess I find someone that can work on such things, kindly offer to have a go at fixing my limping Marantz; or I find another old 70's piece of Quad gear to throw money at
From my perspective CD-4 can be a beautiful lady waiting to be aurally caressed, or as more often, it appears to me at least, a cold hearted soul crushing Bitch!
Yes I'm still in the fight, but my time is running short if I'm going to fully realize this dream.
Here's a sample of the Marantz hum (the Marantz was turned on at about 27 sec. into this one min. mp3 sample) and boosted about 30 dbs so you can hear the hum better.
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I guess I need to go back to the basic question for my system as it is now. Would using the same cart., I use AT15s; and wiring both power and RCAs (good quality Blue Jean LC-1's) create a hum with the only difference being using a CD-4 demodulator. As everything else in the line does not have a hum issue AFAIK. Also, the only other gear (ROTEL TT Preamp. & Surround Master v2) that're close by the TT are things I unplug during CD-4 testing.
