QB restored 7001 & CD-4

[aquadad]

Hello,

I have a QB restored QRX-7001 and I would like to start using it's onboard CD-4 demodulator instead of my JVC-4DD5. At the moment I use the 4DD5 because with the turntable and cartridge that I use I can get good (to my sensibilities) results, w/o the notorious splattering.

As of yet I have not been able to come up with a good enough combination of cartridge and turntable so as to not get the splattering from the onboard demodulator in the 7001. I would love to hear suggestions from those of you who have a QB restored 7001 that are getting good results. What turntable/cartridge combinations are you using?

Thanks

 

[aquadad]

Hello Again,

Now I'm wondering if anyone has ever accomplished good results from the onboard demodulator in the 7001, QB restored or not? I thought that might be a factor because of any mods that might make it more sensitive for better separation and discreteness. As I understand it the 4DD5 defaults to stereo when it gets a weak signal, thus no splattering. That's where I get confused though because I also thought the demod in the 7001 is almost identical to the 4DD5??? And that the Holy Grail demod in the 9001 is an improved upon design, in addition to QB mods.

This is not life and death here I just feel challenged to get a good sound out of the onboard demod in the 7001, but if this is impossible to achieve then I'll stop wasting my time and start saving my money. Here is a list of what I have tried to use so far with no good results:

Technics TT SL-1300 (with integrated low cap cables) https://www.quadraphonicquad.com/forums/showthread.php?t=3541 (see post #21) http://www.vintagetechnics.com/turntables/sl1300.htm

Technics TT SL-5300 (modified with phono plugs and detachable low cap cables) http://www.vintagetechnics.com/turntables/sl5300.htm

Technics TT SL-D2 (modified with phono plugs and detachable low cap cables) http://www.vintagetechnics.com/turntables/sld2.htm

Blue Jean Cables LC-1 low cap audio cables http://cgi.ebay.com/Blue-Jeans-Cabl...DVWQQrdZ1QQcmdZViewItem?hash=item270035947693

Ortofon VMS30 MKII cart (with fine line stylus) http://www.turntableneedles.com/index.asp?PageAction=VIEWPROD&ProdID=9340

Audio Technica AT15Sa cart (w/Shibata stylus) http://www.turntableneedles.com/index.asp?PageAction=VIEWPROD&ProdID=9161

 

[aquadad]

Hello,

I am happy to say that I have finally found a cure for my CD-4 blues. First off I would like to say that I owe it all to QB. He was very patient and generous of his time helping me get all the bugs worked out of my 7001. He did a complete restoration, including tweaking the EQ board, and modifying the power supply upon my insistence that there must be something wrong. More importantly he kept assuring me that the onboard demod in my 7001 wasn't getting the proper signal to work with and that I needed to persevere to find the right hardware to achieve this.

Sorry for being such a pain in the ass Bob. You must get pretty tired of dealing with the same old headache over and over from the uninitiated like myself. I tried in vain to acquire a Sansui quad table and kept getting outbid, (over $200). I finally came across a Kenwood KD-5033F turntable with a V-42 cart and a NIB N-40A replacement Shibata stylus. The V-42 from what I can tell was made for Kenwood by Audio Technica and it's the same as the AT12Sa. It's worth noting that there is a stereo version of this turntable that doesn't have the "F" in the model #,which explains the "F" logo on the face of the table across from the "Kenwood" logo. It probably doesn't have the low cap wiring and interconx.

Anyway with all that said I can now say that the onboard demod in the 7001 does clearly outperform the 4dd5 with much more discreteness and clarity from channel to channel. It took some doing to get it to this point but the end clearly justifies the means and I couldn't be more pleased.

I hope the lack of response to this thread isn't because none of you are getting good results with CD-4 from your 7001's. I now know it's possible and hopefully there are those of you that can say the same. Again, if you have achieved success please post your hardware combo so others don't have to go through this heartache. If not then persevere, it took me two years to get to this point.

In hindsight I suspect that the lack of response was out of respect to QB and deservedly so. He's an icon in our little corner of the world. I can assure you though that my intentions were honorable and that I truly just wanted to know what to be on the lookout for in trying to track down suitable hardware. I had a hollow feeling in my gut paying just under $200 for a fifth turntable and not knowing whether or not it was going to work for me...

Enough of this dribble, back to listening to those CD-4 records. So far I've listened to the Doors Greatest, Seals & Crofts, I'll Play For You and Tomita, Firebird and I got goosebumps from what I was hearing out of each of them. This is awesome!!!!

 

[lonster]

Congrats!!:banana: :banana:

Lonster

 

[soesbeout]

Congrats on your CD-4 performance,Even though I only have the lowly QRX-7500 I have always gotten a solid radar light with the internal demod,and great separation ( to my ears anyway).From the photo of your turntable it looks almost exactly like my Pioneer PL-55DX that I purchased new overseas when I got the Sansui.This model Pioneer has all the cd-4 wireing inside and I paired it with the AT331LP cartidge.I see them on e-bay all the time and I don't think people know that they are pretty cheap and work well for cd-4.

 

[JonUrban]

Actually, I was going to respond to the thread, but I can't remember what turntable I used and it's packed away at the present time. I have a couple of them, and don't remember which one (I have 3 different Sansuis) I used when I got my QRX-999 back from Bob. I know I use a Shure M24H cartridge.

Glad you are "underway"!

 

[QuadBob]

Congrats on your CD-4 performance,Even though I only have the lowly QRX-7500 I have always gotten a solid radar light with the internal demod,and great separation ( to my ears anyway).From the photo of your turntable it looks almost exactly like my Pioneer PL-55DX that I purchased new overseas when I got the Sansui.This model Pioneer has all the cd-4 wireing inside and I paired it with the AT331LP cartidge.I see them on e-bay all the time and I don't think people know that they are pretty cheap and work well for cd-4.

The QRX-7500 has the same demodulator design as the QRX-7001, so properly calibrated performance should be the same.

QB

 

[aquadad]

Hello,

Thanks one and all for finally chiming in, I was beginning to get deserted island syndrome.

In following up on my successful (finally!!!) CD-4 results, "guess what?", I have figured out that my weak link all along has been the cart/stylus combos that I have been using. Even though they all work well through the 4dd5 the results are very misleading because of what the darn thing does when it get's the weaker signal. It sounds clean but at the cost of losing the discrete separation.

I took the new Shibata cart/stylus from the Kenwood and tried it on the modified Technics SL-D2 with the low cap Blue Jean Cables and "woala" excellent sounding CD-4 results through the 7001's onboard decoder. Based on this finding I suspect that all my tables will now perform admirably as long as I use the new cart and stylus that came with the Kenwood table. So now I have gone from having no CD-4 table to quite possibly having five.

I'm sure QB is grinning from ear to ear by now as he reads this. He must of told me a thousand times that only when all the conditions are met properly, would I get good results. In my defense though I did get led down a wrong path by the results I get from the 4dd5, because of how it masks the weak signal. Also, at one time we tested the cart/stylus's that I have through his "holy grail" in the 9001 and although we didnt get the splatterring that I would get in the 7001 we did get varying degrees of separation as evidenced by the meters on his 9001. What this is telling me now is that the "holy grail" does a better job at handling the weaker signals and not that inferior carts work fine for CD-4. At least not in the purest sense.

All this troubleshooting still leaves one stone unturned and that is why do I not get good results from my AT15Sa. The reason that I suspect is because it probably needs a new stylus which, in my stubborness to pay such a high price for, I tried to find cheaper alternatives. I will have to get the new stylus and post my results. In the long run it looks as though the high priced replacement stylus would have been the cheaper route to go.

I think that it is also worth pointing out at this time that just because you're getting good radar it doesn't mean you are getting everything you need to produce great CD-4 results. It just means you are getting good radar which is just the carrier signal. If the carrier signal isn't carrying anything, or if it isn't carrying everything, your results will vary.

All my cart/stylus combos get good radar through both the 7001 and the 4dd5 but only the latest Kenwood cart made by Audio Technica with a NEW stylus gets good CD-4 results through the 7001...

I sure hope all this helps others in their CD-4 quest.

 

[Lucanu]

I have to ask you this:
is there any difference in perfoming between 7001 and 4dd5 using same cart/stylus/TT?
I have both, but due to a defective cd-4 demod on my 7001 I use my 4dd5 and it sounds wonderfully.

 

[aquadad]

I have to ask you this:
is there any difference in perfoming between 7001 and 4dd5 using same cart/stylus/TT?
I have both, but due to a defective cd-4 demod on my 7001 I use my 4dd5 and it sounds wonderfully.

Hello Lucanu,

Good to here from you in this thread because I know in the past I recommended you try the 4dd5 as a quick fix to your problems. I still have high regard for what the 4dd5 can do for quick and easy CD-4 results. If your used to listening to the matrix formats (SQ & QS), or synthed surround from stereo (variomatrix), you won't be disappointed with the 4dd5.

However, if your point of reference is SACD or DVD-A I think you would be better served to get your 7001's onboard demodulator functional. The difference is that extreme. With everything fine tuned through the 7001 there are times when three channels will be cranking while in the fourth channel all you hear is the sound of the needle on the record. Nothing bleeds through. Everything is crisp, clear, and discrete just the way it was originally mixed and intended to be heard.

From what my ears can tell, between the "Holy Grail" in the 9001 and the humbler demod in the 7001, the biggest and most significant difference is the degree of difficulty required to achieve optimal results. With both of these two functioning optimally the 9001 is a notch better in clarity, with a more relaxed (less strained) sound that is also boosted by the 9001's more powerful amps.

Keep in mind these are my opinions based on the comparisons that I have made with my own restored equipment and what I hear when I visit QB on occasion. It bears repeating at this time that in addition to the restoration that included the latest mods to get rid of the 7001's notorious grainy sound (in comparison to the 9001), I also had my EQ board tweaked and the power supply modified. The reason for the power supply mod was that my 7001 was an early run unit that used a weak cap at a critical point that effected the overall performance in various ways. It is my understanding that Sansui even upgraded this cap in there later runs of the 7001.

With all that said you can see why I still stand behind the 4dd5 as a quick and easy fix. In looking back at all I've been through to get to this point, I probably should have listened to Bob 2 years ago when, before all of this began, he kept telling me that I should go with the 9001 instead. Who knew!:yikes

 

[stickwork]

All I can say is that is one sweet table Aquadad!
I've been running a KD-500 as my main table for 20 years, it still sounds incredible and is so solid, a pleasure to use. I've been looking at Luxman 272's to add a second high end table but I keep coming back to Kenwood. If it ain't broke, don't fix it!!

Enjoy that beauty!
Stickwork

 

[Lucanu]

Hello Lucanu,

Good to here from you in this thread because I know in the past I recommended you try the 4dd5 as a quick fix to your problems. I still have high regard for what the 4dd5 can do for quick and easy CD-4 results. If your used to listening to the matrix formats (SQ & QS), or synthed surround from stereo (variomatrix), you won't be disappointed with the 4dd5.

However, if your point of reference is SACD or DVD-A I think you would be better served to get your 7001's onboard demodulator functional. The difference is that extreme. With everything fine tuned through the 7001 there are times when three channels will be cranking while in the fourth channel all you hear is the sound of the needle on the record. Nothing bleeds through. Everything is crisp, clear, and discrete just the way it was originally mixed and intended to be heard.

From what my ears can tell, between the "Holy Grail" in the 9001 and the humbler demod in the 7001, the biggest and most significant difference is the degree of difficulty required to achieve optimal results. With both of these two functioning optimally the 9001 is a notch better in clarity, with a more relaxed (less strained) sound that is also boosted by the 9001's more powerful amps.

Keep in mind these are my opinions based on the comparisons that I have made with my own restored equipment and what I hear when I visit QB on occasion. It bears repeating at this time that in addition to the restoration that included the latest mods to get rid of the 7001's notorious grainy sound (in comparison to the 9001), I also had my EQ board tweaked and the power supply modified. The reason for the power supply mod was that my 7001 was an early run unit that used a weak cap at a critical point that effected the overall performance in various ways. It is my understanding that Sansui even upgraded this cap in there later runs of the 7001.

With all that said you can see why I still stand behind the 4dd5 as a quick and easy fix. In looking back at all I've been through to get to this point, I probably should have listened to Bob 2 years ago when, before all of this began, he kept telling me that I should go with the 9001 instead. Who knew!:yikes

Can you email me a little sample of a decoded cd-4 demo made from the two?
I know how well a 4dd5 can perform (in my little experience), but completely unknown to a QB 7001 modded demodulator.

Thanks!

 

[aquadad]

Can you email me a little sample of a decoded cd-4 demo made from the two?
I know how well a 4dd5 can perform (in my little experience), but completely unknown to a QB 7001 modded demodulator.

Thanks!

Hello Again Lucanu,

I don't have the software to do this and even if I did, my computer and my quad setup are completely segregated. After what I've been through to get a good CD-4 setup, the marriage of my computer to the quad/surround system would probably kill me!

I know there are others among us who have done some really good conversions from CD-4. I don't know what hardware they use to get their source files but I can say this. When CD-4 gets decoded right and the surface noise gets scrubbed out with the various techniques available the results are much improved over anything that I ever get out of my 4dd5 setup. This is what kept me motivated to get my 7001 to work properly.

Furthermore if you are considering a restoration etc., I would have to recommend that you live with what you have and start from scratch to build a new system around a 9001...

Regards, David/Aquadad

 

[Lucanu]

Hi David,

Ehm, just getting a 9001 to me could be a nightmare, in money terms!

but maybe I could start thinking about sending my own cd-4 board to QB, but it means open my 7001, maybe cut wires, send it to QB and wait.
That would solve any problems for my 7001 cd-4 board, but since I have almost perfect results with my setup (I compared separation with Q8s versions) I think I'm gonna keep this.

And BTW have you tried the AT440ML with your "brand new" system?
I'm very happy with that, and Quadfather and other have found this cart/stylus very good for cd-4 playback.

:sun

Regards, Luca.

 

[aquadad]

Hi David,

Ehm, just getting a 9001 to me could be a nightmare, in money terms!

but maybe I could start thinking about sending my own cd-4 board to QB, but it means open my 7001, maybe cut wires, send it to QB and wait.
That would solve any problems for my 7001 cd-4 board, but since I have almost perfect results with my setup (I compared separation with Q8s versions) I think I'm gonna keep this.

And BTW have you tried the AT440ML with your "brand new" system?
I'm very happy with that, and Quadfather and other have found this cart/stylus very good for cd-4 playback.

:sun

Regards, Luca.

Hello Luca,

When you say "compared separation" do you mean by a visual readout of the signals or by what you hear? The reason that I ask is because the muzzled sound of the 4dd5 that I am refering to is probably stemming from the noise floor of the signal. I would think that visually the floor of the signal would be higher for a Q8 than vinyl. Generally speaking the peaks of the signal are where the 4dd5 has no problems with separation. It's the floor where all the loss of crisp, clear, discreteness is lost. Also my 4dd5 isn't recapped like the 7001 which I'm sure contributes to the differences between the two.

 

[aquadad]

From the photo of your turntable it looks almost exactly like my Pioneer PL-55DX that I purchased new overseas when I got the Sansui.This model Pioneer has all the cd-4 wireing inside and I paired it with the AT331LP cartidge.I see them on e-bay all the time and I don't think people know that they are pretty cheap and work well for cd-4.

So--- Hello,

I was looking over my list of turntables that I thought looked like they might be CD-4 capable from their pictures in ebay adds (i.e. the fat interconx). I do have the PL-55DX on the list but I couldn't confirm it's CD-4 capability anywhere at the time. Thanks for the info. I keep seeing the references to the AT331LP and the AT440ML carts so there must be something to that too. All I know from my experience is that I have several carts (most noteably Ortofons) that work with the 4dd5 and don't work on the 7001. But, when it's all said and done the 7001 sounds better.@:

In conclusion if your happy with the results you are getting then leaving well enough alone is the best advice I can give. After all if it's purity you're after, throw on a DVD-A and forget about it.

 

[Lucanu]

Hello Luca,

When you say "compared separation" do you mean by a visual readout of the signals or by what you hear? The reason that I ask is because the muzzled sound of the 4dd5 that I am refering to is probably stemming from the noise floor of the signal. I would think that visually the floor of the signal would be higher for a Q8 than vinyl. Generally speaking the peaks of the signal are where the 4dd5 has no problems with separation. It's the floor where all the loss of crisp, clear, discreteness is lost. Also my 4dd5 isn't recapped like the 7001 which I'm sure contributes to the differences between the two.

Hi David,
I was referring to what I hear. There's always a little blending on the highest frequencies, which I think is normal.